75

3.1 Electrical Motors

Electric motors convert electrical energy into mechanical energy. There are basically 3 types of motors:

1. AC Induction Motors2. AC Synchronous Motors3. DC Motors

The detailed classification of electric motors is given below :

Electric motors are inherently very efficient. Their efficiencies vary from 85% to 95% for motors of sizes ranging from 10 HP to 500 HP. It is still possible to improve the efficiency of these motors by 1 to 4% by improving the design of motor .

3.1.1 Power Consumption in Motors

a) Efficiency and Power Factor

The power consumed by a 3-phase AC motor is given by

Power Input = 3 x Voltage x Current x Power Factor

If the voltage is in Volts and the current in Amperes, the power will be in Watts (w). The power in Watts divided by 1000 is kilowatts (kW). The power input to the motor varies with the output shaft load.

Variations of motor efficiency and power factor with load are shown in Fig. 3.1 Torque speed and current speed characteristics of different types of rotors are shown in Fig.3.2. The load vs full load current is shown in Fig. 3.3. The following may be noted from these curves.

Chapter - 3

Electrical Utilities

Electrical Power input (kW) = Mechanical Shaft Output x 100 Motor Efficiency (%) Electrical Power input (KVA) = Power Input (kW) x 100 Power Factor

Electric Motors

D.C. Motors

Brushless D.C Brush D.C

Shunt Wound

Separately Excited

Series wound

A.C. Motors

Single Phase

Shaded pole

Reluctance

Split Phase

Three phase/polyphase Linear

InductionInduction

Squirrel cage

Slip ring

Synchronous

Synchromous

Compound wound

Notes

76

1. The motor efficiency remains almost constant upto 50% load. Below 50% load, the efficiency drops significantly till it reaches zero at 0% load.

2. At a particular operating voltage and shaft load, the motor efficiency is fixed by design, it cannot be changed externally.

3. The power factor reduces with load. At no load the p.f. is in the range of 0.05 to 0.2 depending on size of the motor.

4. At no load, the power consumption is only about 5% or so, just sufficient to supply the iron loss, friction and windage losses.

5. The no load current is however of the order of 30% to 50% of full load current. This amount of magnetizing current is required because of air gap in the motor.

6. The starting torque is 100% to 200%, the maximum torque is 200% to 300% of rated torque.

7. The starting current remains at a high value of more than 500% of rated current upto 75% to 80% speed and then drops sharply.

Fig 3.1 : Load vs Efficiency & Power Factor.

Fig 3.2 : Performance with Tee Bar, Deep Bar, Trapezoidal and Double Cage Rotors

% E

ffic

ien

cy &

Pow

er F

acto

r

100

90

80

70

60

50

40

30

20

10

0 0 25 50 75 100

Efficiency + Power Factor

% Load j

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

pf%

77

Fig 3.3 : Current v/s Load

3.1.2 Importance of Motor Running Cost-Life Cycle Costs

Motors can run without problems for 20 years or more with good protection and routine maintenance. However, if they are running inefficiently, it is worthwhile replacing them as running costs are much more than first costs. Motors can be considered as consumable items and not capital items, considering the current energy prices. The importance of running cost can be seen from Table 3.1. The following points may be noted:

Table 3.1 : Importance of Motor Running Cost

1. Even a small motor of 7.5 kW consumes, at full load, electricity worth Rs. 20 lakh in 10 years. Similarly, a 37 kW motor consumes about Rs. 1 crore worth of electricity in 10 years.

2. The first cost is only around 1% of the running cost for 10 years, hence running costs are predominant in life cycle costing.

LARGE MOTOR(25 HP & ABOVE)

SMALL MOTOR(BELOW 25 HP)

100

90

80

70

60

50

40

30

20

25 50 75 100

% Load (Shaft Power)

% F

ull

Loa

d C

urre

nt

Motor Rating (kW) 7.5 37

High Efficiency

LowEfficiency

Running Cost

(Rs.) per Annum (@Rs. 4.00/ kWh)

6000

0.86

8.72

6000

52320

209280

2092800

12000

0.57

0.88

8.52

51120

204480

2044800

12000

0.59

0.92

40.22

6000

241320

965280

9652800

70000

0.72

0.93

39.78

6000

238680

954720

9547200

70000

0.73

Efficiency

Power Input (kW)

Running Hours

Energy Input (kWh)

Running Cost (Rs.) for 10 years

First Cost as % of for 10 years

Running cost

High Efficiency

LowEfficiency

First Cost (Rs.)

78

3. Even a small difference in efficiency can make a significant difference in running cost.

4. When economically justified, motors may be replaced, even if these have been recently installed.

3.1.3 Energy Saving Opportunities in Motors

The main energy saving opportunities in motors can be summarized as follows:

a) Stopping idle or redundant running of motors.b) Matching motor with the driven load (sizing of motors)c) Operation of under-loaded Delta connected motor in Star connection.d) Soft starters with Energy Saving Features.e) Use of Variable Frequency Drives (VFDs)f) Improving drive transmission efficiencyg) Use of high efficiency motorsh) Improvement in motor drive systems

Oversized Motors lead to the following problems:

1. Higher investment cost due to larger size.2. Higher running cost due to decrease in efficiency.3. Higher maximum demand due to poor power factor.4. Higher cable losses and demand charges.5. Higher switchgear cost.6. Higher space requirement.7. Higher installation cost.8. Higher rewinding cost (in case of motor burnout)

Table 3.2 Shows the effects of oversized motors on the energy bill and investment

Table - 3.2 : Increased Costs due to Oversized Motors

Motor Rating (kW) 15 30 55

Motor Load Requirement (kW) 15 15

15 Motor Efficiency %

89 89 84

Input Power (kW)

16.85

16.85

17.85

Input Energy (kWh)(for 6000 hrs/ annum)

101100

101100

107100

Motor Power Factor 0.89 0.75 0.50Input KVA 18.93 22.44 35.70Energy Difference (kWh) - - 6000Increase in Running Cost (Rs.)

-

-

24000

Investment (Rs.)

25000 55000 95000

Increase in Investment (Rs.)

-

30000 70000

79

Fig. 3.4 : Motor Performance in Delta and Star Connections

The following suggestions are made :1. If a motor is oversized and continuously loaded below 30% of its rated shaft

load, the motor can be permanently connected in Star.2. If the motor is normally loaded below 30% but has a high starting torque

requirement, then the motor can be started with a suitable starter and, after overcoming the starting inertia, be automatically switched from Delta to Star, using timer control or current sensing. If the load is below 30% most of the time, but if the load exceeds 50% sometimes, automatic Star-Delta changeover Switches (based on current or load sensing) can be used. But, if the changeover is very frequent the contactors would get worn out and the savings achieved may get neutralised by the cost of frequent contactor replacements.

3. If the motor is nearly always operating above 30% of the rated load and sometimes runs below 30% load, a careful analysis is required before installing any arrangement for operation in star connection at light loads.

Case Study 1: ‘Delta' to 'Star' connection in Vegetable Oil Works

Brief

A 25 hp/18.5 kW motor was driving a cooling water circulation pump. The motor was 30% loaded. It was decided to connect the delta connected motor in star. The electrical measurement before & after connection of motor from 'delta' to 'star' is given below:

1. Current (star)2. Current (Delta)3. Power factor (star)4. Power factor (Delta)5. Efficiency (star)6. Efficiency (Delta)7. Speed (star)8. Speed (Delta)9. Change overline

Parameters Before Implementation

(Delta)

After Implementation

(Star)

Saving / Improvement

Voltage (V) 415 415 -

Current (A) 18.5 9.5 9.0 Power Factor 0.5 0.87 0.37

Power Input (kW) 6.72 5.96 0.76 Speed (rpm) 1469 1454

80

Energy Saving

Energy Savings : 0.76 kW i.e. 11.3% Annual Saving : 6080 kWhInvestment : Rs.5000Payback Period : 10 months

Case Study 2: Use of Soft Starter to Facilitate Large Motor Starting with Power Supply from Captive D.G. Set

Brief

Measurements made in a continuous chemical process plant, where a soft starter was introduced to reduce the starting kick when the motor is started on D.G. set, are high-lighted below :

Application : 250 hp Air CompressorMotor Details : 250 hp, 415 V, 3-Phase, 1500 rpm, 313 A

Starting Using Star/Delta Starter

Initial Starting kick : 1800 A for 2 Sec. (Direct)Maximum Starting Current : 480 A (star) / 536 A (delta)Continuous Current : 278 A

Starting With Soft Starter :

Settings : Current Limit - 200% ; Ramp Time - 30 secondsStarting Current Kick : 685 A which Reduces to 155 A in 30 seconds

Benefits : Starting current kick reduced by about 60%. Any dip in voltage at the main busbar of DG Set is reduced. The expenditure on maintenance of the motor and the attached mechanical load is also reduced.

Case Study 3 : VFD for Cooling Tower Pump in a Chemical Plant

Brief

This is a case study from a chemical plant manufacturing resins, used for manufacturing paints. A cooling tower with a 125 HP pump was used for process cooling applications. In the existing system, flow variation was through closing/opening valves at the end use points.

Also, in the existing system, the return water line of the cooling tower was throttled to control the flow. After installation of an inverter to control the motor speed, this valve was fully opened, thus eliminating the throttling losses.

Motor Rating : 125 hp, 415 V, 170A, 2975 rpm.

Valve position Power consumption 20% open 53.5 kW

Fully open 40 kW

Power Saving

13.5 kW

81

Energy Saving

Annual savings : 1,16,000 kWh Annual saving : Rs. 0.47 Million Investment : Rs. 0.5 MillionPayback period : 13 months

Case Study 4: High Efficiency Gear in Place of Low Efficiency Gear (for a Reactor with Worm Gear )

Energy Saving

Case Study 5: Use of High Efficiency Motors in a Textile Plant

Brief

The Ring Frame motor rating was 40 kW. A standard efficiency motor was compared with an energy efficient motor as given in table below:

Energy Saving

Standard Motor vs EE Motor

Parameter Low efficiency Worm gear Saving/Improvementgear

Motor Rating (kW) 7.5 3.75 3.75

Actual Motor 3.75 3.0 0.75

Input (kW)3.75 3.0 0.75

Description Standard (Low Eff) Motor

Energy Efficient (EE) Motor

Motor rating, kW

Efficiency %

Energy consumed, kWh/doff

Weight of yarn per doff

Specific energy consumption, kWh/kg yarn

Annual electricity saving, kWh

Pay back period on extra cost of EE motor, months

40 40

92 94.5

96.22 92.54

44 44.5

2.187 2.080

- 9564

- 5

82

Table shows comparative data of super efficient motors developed by onemanufacturer.

Super Efficient Motor

3.1.4 Emerging New Motor Systems

Emerging motor system improvements can be categorized into the following three areas of development opportunities:

1. Upgrades to the motors themselves, for example:

• super conductive motors• permanent magnet motors• copper rotor motors• switched reluctance (SR) drives• written pole motors• very low loss magnetic steels

2. System design optimization and management, such as:

• end use efficiency improvements• use of premium lubricants• advanced system design and management tools

3. Controls on existing systems, for example:

• multi-master controls on compressors• sensor based controls• advanced adjustable speed drives with improvements like

regenerative braking, active power factor correction, better torque/speedcontrol.

3.1.5 Potential Energy Savings

Primary specific electrical energy savings for particular motor applications are summarized in Table 3.3.

Standard Motor

Super Efficient Motor

Output 15 kW 15 kWFrame Size 160 L 160 LSupply System 415 V +_ 6%; 50 Hz V +_ 3% 415 V +_ 10%; 50 Hz V +_ 5%RPM 1445 1475 Efficiency 89% 93% Fan Plastic C.I

Ambient 40° C 50° CTaking annual running hours 7165 7165

Input kW at full load 16.85 16.13Input kW difference 0.72

Unit Rate (Rs/kWh.) 4

Annual Savings - 20,635Net Unit Price (Rs.) 21940 32200Price difference

-

10,260

Payback

-

19 months

83

Energy Efficiency Estimates for Emerging Motor Technologies

Table 3.3 : Energy Efficiency Estimates for Emerging Motor Technologies

(Source : LBNL :Energy Efficient Techologies for Industries)

3.2 Electric Furnaces

Electricity is a very clean but costly fuel for heating and melting applications. There are number of advantages in electricity use like improved product quality due to absence of fuel impurities, excellent power control, clean environment (pollution is transferred to central power station) and high efficiency at end use point. But since conversion efficiency of fuel to electricity is only 35% at the power station, the overall efficiency from fuel to end use heating is likely to be 15 to 25%. Hence keeping the overall energy scenario in view, electricity should be used for only special heating applications. Fuel should be used directly to the extent possible. For many conventional heating applications like billet heating and heat treatment, alternate fuels, especially natural gas where available, must be considered. Many companies have changed over from electric heating to heating by other fuels to reduce costs.(However for Induction and Arc Furnances no alternatives are presently available ) Table 3.4 gives the inter-fuel substitution.

Technology Energy Savings (%) Notes

New Motors

Superconductor 2 to 10 Higher efficiencies at partial load

Copper Rotor 1 to 3 5% has been reported

Switched Reluctance 3

Permanent Magnet 5 to 10

Written Pole 3 to 4

Controls

MagnaDrive Up to 60 Savings are great compared to non- ASDs. Compared to ASDs (Ajustable speed drive )energy

savings will be less.

PAYBACK drive Up to 60 Savings are great compared to non-ASDs. Compared to ASDs energy savings will be less.

Advanced ASDs 2 Savings are compared to conventional ASDs

84

Table - 3.4 : Interfuel Substitution : Cost of Alternative Fuels

Electricity is used in arc furnaces, induction furnaces, heat treatment furnaces, billet heaters, ovens, infrared heaters, etc.

Case Study 6 : Replacement of Electric Oven by Gas Fired Oven in anEngineering Industry

Brief

3.2.1 Heat Balance and Energy Saving Opportunities

In order to estimate the efficiency of furnaces and also to identify major losses, a heat balance is useful. A heat balance gives information on the energy input, useful energy and major losses.

Table -3.5 : Energy Balance of Coreless Induction Furnaces

Material : Grey IronCrucible Capacity : 3200 KgProduction Capacity : 1600 kg/hr.Power : 733 kWVolt : 968 volts

Energy Source

Coal

Oil

Natural Gas

Electricity

Cost

Rs. 2000/MT

Rs. 20/Kg3Rs. 8/Nm

Rs. 4.50/kWh

Heat Value

4000 kCal/Kg.

10000 kCal/Kg.39000 kCal/Nm

860 kCal/kWh

Cost Per1000 kCalRs. 0.50

Rs. 2.00

Rs. 0.88

Rs. 5.23

Electrical Oven LPG Fired Oven

Existing Oven : 18 kW Rating Cost of Electricity / hr : 0.11 kW

X Rs. 5.00 = Rs. 0.55 (For Auxillaries)

Cost of Electricity/hr : 18 kW x Rs. 5= Rs. 90 Cost of LPG/hr : 1.55 Kg x Rs. 25 = Rs. 38.75

Total Running Cost/hr : Rs. 90.00 Total Running Cost / hr = Rs. 39.30

Savings per Hour = 90.00 - 39.30 = Rs. 50.70 (56%)

Annual Savings: = Rs. 50.70 x 24 hours x 25 Days x 12

= Rs. 3,65,040

Cost of LPG Fired Oven Rs. 63,000

Payback Period 3 Months

85

Energy Input

Heat In Charge

Surface Heat Losses Energy

Soaking Heating

Outer Bell

Inertia Loss

Inner Bell Inertia Loss

Unaccounted Loss

822.75 kWh

167.00 kWh

204.00 kWh

136.10 kWh

250.90 kWh

44.50 kWh

20.25 kWh

Energy Balance Energy (kWh/tonne)

Percentage (%)

Input Energy

Useful Heat 2Coil I R

Radiation Losses

Conduction Losses

Other Unaccounted

660

380

130

97.5

34

18.5

100

58.5

20

15

5.2

1.3

Table-3.6 : Heat Balance of a Heat Treatment Furnaces (Bell Type)

Table-3.7 : Heat Balance in the Arc Furnace

kWh/Liquid Metal Tonne

Steel Plant 1: 170 T Furnace

Steel Plant 2 : 30 T Furnace

Energy Input

Electrical Energy

Carbon Combustion

Other Chemical Reactions

(exothermic)

Combustion of Graphite Electrodes

Total

426

126

70

48

670

682

126

70

64

942

Energy Output

Useful Heat in Liquid Metal

Exhaust Gases

Sensible Heat in Slag

Electrical Losses

Losses During Operation

Conduction, Radiation

Heat Losses ---Electrodes

Unaccounted Losses

Total

392

104

57

47

-

40

12

18

670

426

120

76

60

170

60

12

18

942

86

Table - 3.8 : Energy Balance of a Continuous furnace (Heat treatment furnace conveyor system)

* Mostly due to convective heat loss due to cold air ingress

Case Study 7 : Replacement of an Inefficient, Oversized Oven

Brief

In a fuse gear industry, the major energy consuming equipment was an oven used for drying ink on ceramic parts and softening of brass components. During the energy audit, some measures suggested to reduce the energy consumption were;

a) Reduction of internal volume of the oven to match the basket size.b) Proper sealing of the door to reduce the heat loss.c) Repair of the rear wall of the oven, which had developed cracks, to reduce

heat loss.d) Reduction of weight of basket from 30 kg to 10 Kg.e) Use of ceramic fibre insulation in place of fire bricks to reduce starting time

and reduce thermal inertia.

It was decided to replace the 28 kW oven with a smaller 12 kW oven. The important difference between the old oven and the new oven are highlighted in Table below.

Comparison of Performance of Old and New Ovens

Energy Balance Energy (kWh) Percentage

Total Energy Input per hour 37.4 100

Losses Through Insulation 3.8 10

Losses in Cooling Zone 5 13.0

Losses Due to Conveyor 8.6 23

Useful Heat 10 27

Unaccounted Losses* 10 27

87

Energy Saving

Annual energy saving : 30,000 kWh Investment : Rs.61,000/-Payback period : 13 months

3.2.2 Energy Savings by Operational Features

a) Operate at full power and capacity as far as possible to get as high a utilization rate as possible. Poor capacity utilization of electric furnaces cause a large wastage of energy. Holding periods can be kept to a minimum. Separate holding furnaces can sometimes be useful.

b) Minimise tapping time and frequency to reduce radiation losses and to reduce operation at low power levels.

c) Charging system should be such that charging time and frequency are minimised. Possibility of charge compacting and preheating can be explored.

d) Molten metal handling and transfer system including ladles can be designed in such a fashion that transfer time and loss in temperature are minimised. Ladle preheating system lead to savings. Well insulated ladles are also necessary.

e) Opening of furnace lids, slagging door etc. must be minimised.f) For heat treatment furnaces, production can be so planned that once a furnace is

started, it can be utilised continuously, otherwise a lot of energy is wasted in heating the furnace itself. Capacity utilisation is also very important.

g) For many heat treatment applications, it may be worthwhile collecting jobs so that full capacity utilisation is achieved.

h) Weight of jigs and fixtures for heat treatments should be minimised. o oi) Surface temperature may be kept at 45 C to 60 C for heat treatment furnaces to

reduce radiation losses.j) Process parameters, like heat treatment cycle time and temperatures, have to be

checked.

Case Study 8 : Electrical Energy Conservation in a Foundry through operational improvement .

Brief

The plant is equipped to produce about 350 tonnes of Malleable Iron and S.G. Iron Castings per month.

Steel scrap is melted in two 4 tonne / 1150 KVA mains frequency furnaces. The product mix consists of a large number of relatively low and medium weight castings. Moulds are made on automatic moulding machines (Pneumatic). The castings are shot blasted, annealed in electric furnaces (600 kW). Fettling and grinding also uses pneumatic tools. These are fed by two compressors of 93 kW each, working one at a time.

The present production level is around 220 Tonnes / month. Energy consumption is about 700,000 kWh/month with a maximum demand of around 2700 kVA.

Approximate percent consumption of major equipments are given in the Table below.

88

% Distribution Among Major Loads On A Typical Day

Energy saving was achieved through operational improvement like compacting the scrap and loading it with crane, closing the furnace lid, shutting off the ventilation fans for capacitor cooling during favorable ambient conditions etc.

Energy Saving

Case Study 9: Replacement of inefficient arc furnace with induction furnace

Brief

Background : A leading automobile components casting foundry had two indirect arc furnaces of capacity 30kg and 80kg respectively. These furnaces were used for producing specialized automobile components. Smaller capacities of the existing furnace meant the number of melting batches was high and correspondingly the fixed heat loss component was very high.

These inefficient arc furnaces were replaced with one medium frequency (3000 Hz) induction furnace of capacity 125 kW, having two pots 50 kg and 100 kg respectively. The 50-kg pot is rated at 90 kW while for the 100-kg pot rating is125 kW.

Energy Saving :

Total load

Melting Furnaces

Annealing furnaces

Compressors Sand Plant

Other Loads

Lighting

% of Total load

100 60 17.14 11.48 2.55 6.52 2.28

Parameter Before After Saving/Improvement

Implementation Implementation

SEC (kWh / T) 900 700 ( - ) 200

Charging time (hrs.) 10 4 ( - ) 6

Annual Saving (kWh) - - ( - ) 1,22,070

Radiation loss (kWh/day) 500 - ( - ) 1,00,000

Ventilator fan for 15 NIL ( - ) 30,000 kWh/annum

capacitors (HP)

Particulars Units Before implementation (Indirect arc Furnaces)

After implementation

Improvement

% Improve

ment 30 kg IAF

80 kg IAF

Total / avg.

Monthly energy consumption

kWh 14434 6280 20714 8267 12447 60

Metal tapped per month Kg 13970 2100 16070 13974 -2096 -13 No of heats per month No 438 27 465 330 -135 -29

Specific energy consumption per Mt.

kWh 968 2990 1085 592 494 60

Annual energy consumption

kWh 173208 75360 248568 99204 -149364 -60

Cost of energy Rs 621816 270542 892359 356142 -536217 -60 Annual energy savings kWh 149364

Annual cost savings Rs 536217 Investment incurred Rs 1000000

Payback period Years 1.86

2

89

Case Study 10: Modification Annealing Ovens in a cable manufacturing industry

Brief

A cable manufacturing industry, has several annealing ovens, which account for a significant portion of the electricity consumption. A 317 kW oven is used for annealing aluminum conductor in large drums. The oven was large for the jobs being handled. It was redesigned for the job, cutting ceiling height and the insulation was changed to ceramic fibre. The observations are as follows :

Energy saving

Annual Savings : Rs. 1.2 MillionInvestment : Rs. 0.25 MillionPayback period : 3 months

3.3 Compressed Air System

Compressed air is one of the most expensive utilities in manufacturing facilities. First used more than a century ago in pneumatic drills for mining, compressed air has now become an indispensable and a productivity improvement tool for a number of applications ranging from air powered hand held tools to advanced pneumatic robotics. Cost of energy in the compressed air is at least 5 times that of electricity. The energy content in compressed air is further reduced by pressure drop in distribution systems, leakage etc. as shown in fig.3.5. Hence it is important to manage generation, distribution and utilisation of compressed air from energy efficiency viewpoint.

Fig . 3.5 : Energy Flow Diagram

Parameters Before After Savings/Improvement

Implementation Implementation

Energy Consumption (kWh) 1930 500 ( - ) 1430

Time needed (hrs.)

(5 Tonne charge) 8.5 3.5 ( - ) 5.0

Production

(Charges per day) 3.0 5.0 (+ ) 2.0

90

3.3.1 Analysis of Compressed Air System

3.3.1.1 Data Collection

As a first step towards managing energy use in compressed air system, the following information should be collected. This exercise if done systematically can be extremely useful for identifying energy saving potential.

1) Specifications of each compressor such as capacity, pressure, motor ratings etc.

2) Loading and unloading pressure setting of each compressor3) How many compressor normally operate and whether any shift-wise or daily

variation in number of compressors operated4) Collect data on end- use of compressed air in the plant, such as : Pressure, flow,

end use, dryers, regulators, etc.5) Pipe size and its layout

3.3.1.2 Analysis Of Equipment and System Performance

The following actions need to be taken to estimate the compressed air system parameters:

a) Estimation of capacity of each compressorb) Measurement of power input to the compressor at full load and part load

conditionsc) Estimation of total compressed air leakage in the plant and section-wise

leakage estimation if possibled) Conduct a survey of compressed air leakage points by soap solution method or

by using ultrasonic leakage detector.e) Estimate pressure drops in headers. f) Loading & unloading pressures and loading and unloading time of

compressors .

3.3.1.3 Estimation of Capacity of Compressors

The ideal method of estimating air compressor capacity is to use flow meters. In the absence of flow meters, the capacity can be estimated on site by the Pump-Up test. The compressor capacity can then be estimated by using the following formula:

Where,

3Q = Capacity of the air compressor, Nm /min2P = Initial pressure, (kg/cm a ) 1

2P = Final pressure, (kg/cm a ) 22Pa = Atmospheric pressure (kg/cm a )

3Vr = Receiver volume, m (including piping from compressor to receiver and up to receiver outlet valve and also oil separator volume for screw compressors)t = time taken to raise the pressure from P to P , minutes1 2

Tc= Temperature correction factor (= Tr/Ta)Tr = Air temperature in receiver, °K (i.e. °C + 273 )Ta = Ambient temperature, °K (i.e. °C + 273 )

TcQ = (P - P ) Vr 2 1

Pa t x x

91

The pump-up test described above gives only an estimate of the compressor capacity and cannot be considered as very accurate. It is only a simple practical method under site conditions with minimal instrumentation. A more scientific method of conducting the pump-up test with proper installed instrumentation is available in IS:5456-1985.

The power consumption can be measured with portable power meter or energy meter and the specific power consumption (kW/100cfm) can be calculated. Some of the common causes of higher Specific Power Consumption are:

- Poor inter-cooler performance.- Malfunctioning of discharge and/or suction valves.- Worn out piston rings.- Choked suction side filters.

Case study 11 : Installing Refrigeration dryers in Compressed Air system

Brief

It is recommended to replace absorption type air dryer with refrigeration type dryer as absorption dryer uses 10% - 15% purge air for re-generation of desicant .

Energy Saving

Saving Obtained by installing Refrigeration Dryer in Compressor

Case Study 12 : Installation of automatic drain traps in compressed air network

Brief

In an engineering unit, moisture traps were found stuck up in either open or closed condition thus making a loss of compressed air continuously or corroding of pipeline and other networking devices. On rectifying the faults, savings were as under:

Energy Saving

Parameter Before Implementation

After Implementation

Saving / Improvement

Actual load (kW) 16.6 14.11 2.49

Total running hours / year 1800 1800 -

Annual Energy consumption (kWh)

29880 25398 4482

Annual savings (Rs.) - - 15780Investment (Rs.)

-

-

94000

Payback period (years) - - 6

Particulars Actual energy savingsAnnual total energy savings, kWh 84,000 Annual Cost savings, Rs. (million) 0.42 Cost of implementation Rs. (million) 0.10 Simple payback period (months) 3

92

Case Study 13 : Improving the performance of 500 cfm reciprocating compressor

Brief

In an engineering company, plant was having 3 nos - air compressors of IR make. All the three compressors were run continuously totaling to air requirement of 980 cfm. While the performance of 2 nos air compressors of 240 CFM each was found

rdsatisfactory, the 3 compressor of 500 cfm was performing sub standard. The volumetric efficiency was only 87 % and the power consumption was more (20 kW/100 cfm) as against 19.4 kW/100 cfm. Efficiency of the compressor 3 had gone down. By improving the performance of this compressor, one compressor of 240 cfm was totally stopped. After maintenance the savings effected were as under:

Energy Saving

3.3.1.4 Estimation Of Air Leakage Level

Leakage of compressed air is a major reason for the poor overall efficiency of compressed air systems. It may be noted that, at 7 bar (100 psig), about 100 cfm air leakage is equivalent to a power loss of 17 kW i.e. about Rs. 0.62 million per annum.

The leakage level can be estimated by observing the average compressor loading and unloading time, when there is no legitimate use of compressed air on the shop floor.

3Air Leakage in m /min, q =

Where,

3Q = Compressor capacity, in m /min (as estimated from the pump-up test)T = Time on load ,min t = Time on unload, min

Leakage points can be identified from audible sound. For small leakage, ultrasonic leakage detectors can be used. Soap solution can also be used to detect small leakage in accessible lines. The following points can help reduce compressed air leakage:

a) Reduce the line pressure to the minimum acceptable.b) Selection of good quality pipe fittings.c) Provide welded joints in place of threaded joints.d) Sealing of unused branch lines or tappings.e) Provide ball valves (for isolation) at the main branches at accessible points.f) Install flow meters on major lines.g) Avoid installation of underground pipelines to avoid corrosion & leakage.

Particulars Actual energy savings Annual total energy savings, kWh 74,000 Annual Cost savings, Rs. (million) 0.340 Cost of implementation Rs. (million) 0.100 Simple payback period (months) 4

Q x TT + t

93

1/64

0.211

0.0207

744

1/32

0.845

0.083

2981

1/16 3.38 0.331 11925

1/8

13.5

1.323

47628

1/4

54.1

5.3

190865

1/64

0.406

0.069

2485

1/32

1.62

0.275

9915

1/16 6.49 1.10 39719

1/8

26

4.42

159120

1/4

104

17.68

636480

Orifice Diameter(in inches)

Air Leakage

Scfm Power

Wasted kWCost of Wastage,

Rs. (for 8000 hrs/year) @ Rs. 4.50/kWh

At 3 bar (45 psig) pressure

At 7 bar (100 psig) pressure

Leakage tests can be done separately for each section of the plant by isolating the supply to compressed air to the remaining sections of the plant during the leakage test.

Case Study 14 : Cost of compressed air leakage from holes at different pressures

Estimation of Pressure Drop

The pressure loss from the air compressors to the end-use points may be kept at as low a level as possible, i.e., below 0.3 to 0.5 bar.

The air compressors should be located close to the equipment requiring large quantum of air for reducing pressure drops. If the end-uses are spread over a large area, a ring main header can help reduce pressure drop. The pressure drop in pipelines is approximately proportional to the square of the air velocity. The pressure loss can also be calculated for straight pipe lines by the following formula

4 1.85Pressure drop (in bars) = 7.5 x 10 x Q x L5d x p

where,3Q = Air flow in m /min. (Free air)

L = Length of pipeline (m)d = Inside diameter of pipe, mmp = Initial pressure, bar (absolute)

Case Study 15 : Pressure drop calculation for a 3" header and a 4" header for a flow of 100 scfm and a pressure of 7 bar, based on the above equation

94

Brief

Normally, the velocity of compressed air should not be allowed to exceed 6 m/s.

Pipe fittings like valves, elbows & no. of bends etc. also contribute to additional pressure losses.

Case Study 16 : Pressure Drop (in bar) In different Pipe sizes of 100 ft. Length

Brief

Case Study 1 7 : Reduction in pressure drop in the compressed air.

Brief

A leading bulk drug company has three reciprocating compressors having the capacity of 280 cfm and the corresponding power consumption was 58 kW at 7.5

2 2kg/cm . The actual air requirement at user end was only 6.0 kg/cm . The pressure 2drop in the system was taking place of the order of 1.5 kg/cm . On analysis, it was

found that high pressure drop in the system was due to under sizing of the piping. The existing(2") piping was replaced by suitable sized piping (3"). Overall saving in energy was as under:

Energy Saving

Description Units 3" Header 4" Header

Inlet pressure bar, abs 7 7

Air flow scfm 100 100

Length of pipe meter 100 100

Pipe inside dia. mm 75 100

Pressure drop bar 2.1 0.5

psi 30.9 7.3

Nominal pipe size

(in inches)

FAD, cfm(Free AirDelivery)

Line Pressure, psig

1

23

4

6

10

2050

100

200

4.39

0.540.43

0.41

0.24

3.70

0.460.36

0.34

0.21

2.68

0.330.26

0.25

0.19

2.09

0.260.20

0.19

0.16

1.72

0.210.17

0.16

0.14

40 50 75 100 125 150

1.46

0.180.14

0.14

0.11

Particulars Actual energy savingsAnnual total energy savings, kWh 35,000Annual Cost savings, Rs. (million) 0.123Cost of implementation Rs. (million) 0.25Payback period (years) 2

95

3.3.2 Identifying Energy Saving Opportunities

It is very important to have a systematic approach for saving energy in compressed air system. The fundamentals of this approach are basically:

1. Manage end use of air. This includes proper understanding of end use requirement, often termed as the ultimate goal to be achieved.

2. Match the system with the end use requirement in the most efficient way. 3. Improve the efficiency of compressors and related equipments through

maintenace.4. Scouring (moisture removal) by compressed air can be replaced by high

pressure blowers. The energy saving can be 80%. 5. Material conveying applications can be replaced by blower systems or

preferably by a combination of belt/screw conveyers and bucket elevators. 6. For applications like blowing of components, use of compressed air amplifiers,

blowers or gravity-based systems may be possible. 7. Use of compressed air for cleaning should be discouraged. 8. Replacement of pneumatically operated air cylinders by hydraulic power

packs can be considered.9. Use of compressed air for personal comfort cooling can cause grievous injuries

and is extremely wasteful. If a ¼" hose pipe is kept open at a 7 bar compressed air line for personal cooling for at least 1000 hours/annum, it can cost about Rs. 1.0 lakh/annum. Operating cost of a 1.5 TR window air conditioner for the same period would be only about Rs. 12,000/- per annum.

10. Use vacuum systems in place of venturi system.11. Mechanical stirrers, conveyers, and low-pressure air may mix materials

far more economically than high-pressure compressed air.12. Air conditioning systems can cool cabinets more economically than

vortex tubes that cool by venting expensive high pressure air.

Case Study 18 : Installation of VSD on a compressor to avoid the compressed air blow-off in the system

Brief

The chemical plant has five process fermentors, where the compressed air is used as raw material and as well as for the agitation. Five large compressors in use were of reciprocating, single stage, double acting, horizontal, non-lubricated type having

3 2the capacity of 4000 m /hr, rated pressure 1.5 kg/cm , rated motor 200 kW. In view of the variations in the load and the energy lost due to bleed off, variable speed drive was installed to adjust the speed based on requirement.

Energy Saving

Particulars Actual energy savings 3Average bleed air quantity(m /hr)

Annual total energy savings, million kWh

Annual Cost savings, Rs. (million)

Cost of implementation Rs. (million)

Payback period (months)

1320

0.580

1.52

2.0

16

96

Particulars Actual energy savings

Annual total energy savings, million kWh

Annual Cost savings, Rs. (million)

Cost of implementation Rs. (million)

Payback period (months)

0.873

2.9

2.0

9

Case Study 19 : Energy saving in compressed air system by eliminatingartificial demand

Brief

In a manufacturing industry, compressed air is the major utility used in many applications. The industry has 2 centrifugal compressors of 3000 cfm each and 3 reciprocating compressors of 1000 cfm each. 1 centrifugal compressor and 2 reciprocating compressors are always running totaling to 5000 cfm. It was observed that there was a fluctuation of pressure from 98 psi to 67 psi. Two intermediate control stations each of 4500 cfm have been installed which reduced the fluctuation of pressure from 31 psi to 2 psi. Energy saving potential was as under:

Energy Saving

Case Study No. 20 : Saving due to pressure optimization

Brief

In an automobile plant, it was reported that the maximum air pressure requirement 2 2.at machine end is 6.5-7.0 kg/cm but plant is maintaining 7.0- 8.5 kg/cm

Generating higher pressure than required is a loss of power i.e roughly 4% loss in 2maintaining 1 kg/cm higher pressure. The details of losses are as follows:

Energy Saving

2Pressure requirement : 6.5-7.0 kg/cm2Pressure maintained : 7.0-8.5 kg/cm

Rated Compressor power : 75 kW for 458 cfm compressorRated Avg. compressor power : 65 kW( ON and OFF load)Avg. compressor power (ON and OFF load)

2after reduction in pressure by 1 kg / cm : 62.4 kW

Particulars Actual energy savings Annual total energy savings,kWh

Annual Cost Savings, Rs.

Cost of Implementation

Payback Period

10,00061,000

NilImmediate

97

Case Study 21 : Monitoring of air consumption using hour meter installed atcompressor motor and reduction of air leakages

Brief

In a paper and pulp industry, for supplying instrument air, two compressors working 2 3at 10 kg/cm and 1 m per minute were running. The air leakage in the system

increased and the air compressors started running for more than 20 hrs a day to meet the requirement. Upon installation of the hour meters, it became easy to monitor the running hours of compressors and also estimate the air consumption as well as leakages .The leakages were arrested and also a reduction in total running hrs of compressors was achieved . Savings effected were as under:

Energy Saving

Case Study 22 : Arresting of air leakages in an automobile unit

Brief

A leading automobile unit, which produces 2 wheelers, has seven large compressors with a rated output of 7500 cfm. Compressors consume about 60 lakh units annually (i.e about 12 % of total power consumption). The compressed air is mainly used in pneumatic tools, instruments, control valves. During the recently concluded energy audit, it was observed that the leakage in the system was 1400 cfm, which was about 20% total air consumption. After arresting the leakages, the savings to the company were as under:

Energy Saving

Particulars Actual energy savings

Annual total energy savings, kWh 75,000

Annual savings, Rs. (million) 0.3

Cost of implementation Rs. 2,000

Payback period (months) <1

Particulars Actual energy savings

Annual total energy savings, kWh 0.864

Annual Cost savings, Rs. (million) 3.0

Cost of implementation Rs. (million) 0.2

Payback period (month) 1

98

3.4 Pumps, Blowers, Fans & Variable Speed Drives

Pumping of water and blowing of air are very basic needs. This can be done by either positive displacement systems like reciprocating pumps, gear pumps, roots blowers etc. or by the centrifugal pumps and blowers. Centrifugal devices do not use a rubbing barrier as in positive displacement equipments but depend upon the kinetic energy imparted to water or air due to rotating motion. They are used in majority of applications needing FLOW due to their inherent reliability, ruggedness and reasonably good efficiency.

Basic energy is proportional to the product of FLOW and TOTAL PRESSURE HEAD. The head is mainly friction head and static head.

The static head is a function of choice of location and inherent system design while the friction head varies inversely with fifth power of pipe diameter and other flow passages as also to the square of FLOW. The friction based energy is thus decided by CUBE OF FLOW.

Optimizing the energy efficiency of a pumping system needs attention, action and investments to use the highest possible pump efficiency, to use the pump around its Best Efficiency Point (BEP) which is at a unique flow, to minimize pipe and exchanger losses, minimize/eliminate use of valves and select Minimum Needed Flow under ALL operating conditions. This may call for variable flow systems in many cases to suit operation or to SAVE energy. Changing flow will need retuning the system for optimization.

Incorporating efficient pump and method of flow capacity control at the design stage or as a retrofit by using variable speed, trimming of impellers, variable pitch designs (axial flow), changing impellers and change of pumps along with minimal flow concept and better (bigger) heat exchangers, summarises the total concept of energy saving measures.

The equations relating rotodynamic pump performance parameters of flow, head and power absorbed, to speed are known as the Affinity Laws and are as follows:

Where:Q = Flow rateH = HeadP = Power absorbedN = Rotating speedEfficiency is essentially independent of speed

Flow: Flow is proportional to the speed

Q / Q = N / N 1 2 1 2

Head: Head is proportional to the square of speed

H /H = (N ²) / (N ²)1 2 1 2

Power (kW): Power is proportional to the cube of speed

kW / kW = (N ³) / (N ³)1 2 1 2

Q N2H N 3

P N

99

The operation of fan is similar. There is no static head. The head in the heat exchanger is small compared to head lost in ducts, bends and dampers. In addition to the elegant universally applicable variable speed method of capacity control, we can use variable pitch designs and inlet guide vane control for fans.

3.4.1 Energy Saving in Pumps

Basically, for an ideal system with given piping, the open valve system characteristics should cut the pump curve at BEP flow (Best Efficiency Point Flow). But this is rarely possible. Hence, a practical system suffers in varying degrees by :

1. Loss due to drop in efficiency of the pump for off duty point operation.2. Loss in throttling valve to some extent.3. Piping size of historical value and layout which can be changed.4. A pump of old design which has room for improvement.5. An old heat exchanger, where the design emphasis may be on lesser material

content (low first cost) and smaller space giving relatively higher drop for same function.

6. It is very important to realise that the effects of flow may be proportional to first power of Q (heat exchangers have even Q0.8), so that reduction in flow by even marginal percentage brings about considerable energy savings.

7. An unquestioned Static Head can be altered in some cases by re-layout and other innovative changes.

8. Very large drop (relative) in throttling valve which can be minimised or eliminated.

9. There is a fair chance of improving new working point pump efficiency to increase savings.

The methods for saving energy by altering the pump characteristic are briefly as under :

1. By trimming the impeller i.e. reduction in impeller diameter.2. By changing the impeller to get a different characteristic.3. By a change of blade angle in axial flow type if that feature exists/or installed.4. By changing the pump if the change is drastic/also for more efficiency.5. By change of Speed - Most elegant and universally applicable method.6. By stopping of pump, if parallel operation is properly planned.

Case Study 23 : Eliminating Throttling Losses by Use of Variable Speed Drive

Brief

Figure below shows a system with an unthrottled flow of 12000 lpm and a variation upto 6000 lpm. The pump efficiency figures are shown on the head-flow curve. The best efficiency of 85% is at 12000 lpm which is lowered to 69% at 6000 lpm. Static head is 10 metres. The throttled operation parameter are shown in the Table below.

100

Throttling Losses and Savings By Use of Variable SpeedPump Performance With Throttling Control

Energy Saving

The same system was equipped with an inverter with 97.5%, efficiency changing to 89.5% at reduced load (See Table below).

Pump Performance With Variable Speed

Flow lpm System Pressure (m) Pump Pressure (m) Pump Efficiency (%) Pump Input (kW) Motor Load (%) F.L Motor Efficiency (%) Motor Input (kW) Starter Efficiency (%) Input (kW)

12000 23.50 23.20 86.00 53.58 97.41 90.00 59.53 99.80 59.65

9000 17.93 27.50 79.50 50.87 92.49 89.60 56.77 99.80 56.88

6000 13.35 29.50 69.0041.9276.20 89.00 47.10 99.80 47.20

Flow lpm 12000 9000 6000System / Pump Pressure (m) 23.50 17.93 13.35Pump Efficiecny (%) 86.00 85.50 78.00Pump Input (KW) 53.58 31.02 16.78Motor RPM 1450 1210 1000Motor Load % F.L. 97.40 56.40 30.50Motor Efficiency (%) 93.70 93.60 90.00Motor Input (kW) 57.18 33.14 18.64Controller Efficiency % 97 94 89.50Input (kW) 58.95 35.25 20.83Savings Inputs (kW) 0.70 21.63 26.37% Saving (Throttled - Input) 1.12 38.03 55.80

101

Case Study 24 : Modification of Pumps at a Fertilizer Plant :

Brief

An in-house energy audit by Technical Services department revealed mismatches due to insufficient data at design stage or extra safety margins. A large number of impellers were trimmed. In the Ammonia plant, 6 numbers of cooling water pumps of 960 kW motors were being operated to maintain cooling water pressure at 5 Kg/Sq. cm. Gauge. After the system study, it was decided to operate at lower head and higher flow. One heat exchanger at a height was served with a booster pump. This measure saved 500 kW. Table below summarises different saving measures resulting in a saving of 774.4 kW.

Energy Saving

Modification on Pumps at a Fertilizer Plant

Additionally

1. Ammonia CW pump was totally stopped saving 500 kW .2. One G.S.W. pump was stopped due to inter-connection of C.W and G.S.W,

thereby saving 80 kW.

Case study 25 : Replacing the inefficient pumps with energy efficient pumpsmatching the characteristics with the others connected in parallel

Brief

In one of the Jal Board boosting stations, there were 6 nos pumps-3 of 125 HP and other 3 of 100 HP pumps. While the 125 HP pumps were giving their efficiency near to the rated efficiency of 58 %, the 100 HP pumps were giving efficiency in the range of 13% to 19 %. The efficiency had gone down as these were run in parallel with 125 HPpumps, which were having different characteristics. Further, the head generated by these pumps was much higher than required as the flow was being throttled.

Energy Saving

Replacement of 100 HP pump by energy efficient pump with VFD

Energy saving : 0.185 Million kWhrAnnual saving : 0.74 MillionInvestment : 1.2 MIllionPayback period : 20 months

Description Power Original Data After Modification

Flow Dia Cons. Head Flow Dia Cons. Head Saving3 3M /hr Mm kW M M /hr Mm kW M kW

Condensate 150 321 159 220 150 291 130 180 29

Hot Condensate 150 346 83 175 150 320 70.2 150 12.8

C/X - 102 Conds. 82.1 258 57 155.3 82.1 202 35 146 22

C/X - 701 Conds. 60.2 250 45 158 60.2 203 27 95 18

C/X - 101 Conds. 102 280 63 158 102 NA 38 95 20.2

D.M. Transfer 125 306 60 128 125 294 55.4 118 20.5

Treated Ammonia Conds. 186 350 125 102.6 186 320 104.5 86 20.5

Treated Amm. Conds. 186 350 125 102.6 186 320 104.5 86 20.5

102

Case study No. 26 : Use of one high capacity pump in place of 4 nos of small capacity chilled water pumps

Brief

No. of Pumps in parallel : 4 (20 HP each) Capacity of pumps : 20.5 lps, 43.75m Valve throttled : 60%-80%New pumps (1 no.) : 50 HP

Instead of 4 nos. of Pumps, one big pump of 50 HP motor and energy efficient pump was installed. Savings effected were as follows:

Energy Saving

Annual energy saving : 0.123 Million kWhrAnnual cost saving : Rs 0.637 MillionInvestment in modification : Rs 0.370 MillionSimple payback : 7 months

3.4.2 System Operation and Energy Saving Methods for Blowers/Fans :

Fig. 3.6 shows a fan performance curve for flow reduction from 0.66 per unit to 0.50 per unit. The system head characteristic does not have static head in the case of blowers and fans. The system resistance consists of dampers, ducts with bends etc. and diffusers or such other equipments. The system curve follows the expression KQ2 which is a parabola starting from origin.

Fig 3.6 : Fan Performance with Variable Speed Operation

All the points listed under pumps are applicable to blowers/ fans. The loss in damper at reduced flow is shown in Fig. 3.6 by shaded areas. Due to absence of static head, a larger proportion of energy is dissipated in dampers. Capacity control saving methods are listed below alongwith energy related comments:

1. By outlet damper - Reduces energy use but relatively large damper loss.2. By inlet damper - Reduced suction reduces effective density to give reduced

head/flow. Better compared to outlet damper.

103

3. By Inlet guide vane - Introduces prerotation to add tangential velocity at inlet to improve entry conditions with reduced flow. Better compared to dampers.

4. Changing to better suited blower/fan.5. By changing blade angle in axial flow fans if applicable. 6. By changing the speed, which is applicable to all blowers/fans.7. By stopping redundant fans/blowers. 8. Improved design FRP fans for cooling towers have given 10% to 30% savings.

Case study 27 : Replacement of Inefficient fans

Brief

The test results for the individual fans show that there is mismatch between fan selection and the exact requirements and the operating static pressure of these fans is between 13% and 60% of the rated pressure and the flow of fans is between 90% and 150% of the rated flow. This mismatch has resulted in low operating efficiency of the fan system. It is suggested to replace the low efficiency fans with high efficiency fans.

Energy Saving

Calculation for kVA Savings by Changing the Fan Motor (OnlyCooler Fan-1 is taken for example)

* The impeller power for the new fan is calculated by taking 10% margin in present flow. 15% margin in present static pressure and 90% fan efficiency for cooler than (for other fans - 75% fan efficiency)

Total energy saving for all the fans in above table (kWh/t clinker) : 1.037Annual saving : Rs.2.2 MillionInvestment : Rs.2.4 MillionPayback period : 13 months

Sl. No.

Fan Name % of Flow % of Static Pressure

Static Efficiency

1 Cooler fan A 89.78 55.65 55.00 2 Cooler fan B 127.36 45.84 65.10 3 Cooler fan C 86.74 59.09 58.84 4 Air fan 119.32 27.99 36.88 5 Reverse fan 99.65 27.00 16.93 6 Mill fan 35.03 39.08 18.70 7 Cement fan 19.41 13.43 4.19 8 ESP fan 30.99 13.54 9.97

Parameter Before Implementation

After Implementation

Saving/ Improvement

Power consumption (kW)

108 78 ( - ) 30

Power factor 0.80 0.85 ( + ) 0.05 Annual saving (Rs.) - - ( + ) 4,92,480

104

Case Study 28: Speed Reduction of Vacuum Blowers and Agitators in Pulp &Paper Industry

Brief

(a) Some of the vacuum blowers of PM 1 were being operated with dampers closed to a greater degree. The blowers are belt driven. The pulley sizes are changed to reduce the speed of the fans.

(b) Speed reduction was carried out on new bleached high density tower agitator. (c) The plant personnel decided to operate the blower at 2100 rpm and keep the

damper fully open. After implementation, the power consumption was measured to be 17.4 kW.

Energy Saving

(a) Annual Saving : Rs. 0.12 Million Investment : Rs. 0.1 Million Payback period : 10 months

(b) Annual Saving : Rs.93000 Investment : Rs.15000 Payback period : 2 months

(c) Energy Saving : 16 kWh Annual energy saving : 96000 kWh Annual saving : Rs. 0.48 Million Investment : Nil Payback period : Immediate

Case study 29 : Interconnection of Blowers in the plant

Brief

There are 7 nos. of 3000 cfm (6" head) blower for machine exhaust. It is suggested to inter-connect the blower with damper so that minimum number of blowers can be run common to all machines and can also be run independently if required.

Energy Saving

Annual saving : Rs. 1,62,940Investment : Rs. 25000Payback period : 2 months

Case Study 30 : Replacement of Variable Speed Fluid Coupling (VFC) withVariable Frequency Drive (VFD) in Pulp & Paper industry

Brief

The variable fluid coupling was replaced with a variable frequency drive for I.D. fan of soda recovery boiler, for furnace draft control. The fan was operating around 740 rpm, whereas motor speed was 970 rpm. Recognizing the efficieny difference between VFC and VFD, VFD was installed to replace VFC.

105

Energy saving

Average running kW of ID fan with VFC : 55 kWAverage running kW of ID fan with VFD : 13 kWEnergy saved/day (42 x 24 hours) : 1008 kWh Annual saving : Rs. 0.647 MillionInvestment : Rs. 1.2 MillionPayback period : 2 years

Case Study 31: Installation of Variable Frequency Drive for Control of ID Fans in place of Inlet Damper Control in Pulp & Paper Industry

Brief

50 tph AFBC boiler was provided with 2 nos. ID fans. The furnace draft was being controlled by varying the inlet damper position of ID fans. Each ID fan is driven by 90 kW motor, 750 rpm. The normal damper opening when boiler was at full load awas 55%. It was decided to install 2 nos. 90 kW VFDs for fan control.

Energy Saving

Power consumption before VFD : 84 kW (each motor)Power consumption after VFD : 58 kW (each motor) Annual Saving : Rs. 0.75 MillionInvestment : Rs. 1.1 MillionPayback period : 18 months

Case Study No. 32 : VFD in Pump in Paper Plant

Brief

Industry : PaperApplication : Pump (Water Suction)Motor Rating : 3 Phase AC Induction Motor

Rating : 130 HP - Volt : 415 VCurrent : 160 A - RPM : 1440

Previous System : Motor was run through Star-Delta Starter

Problem Observed : 1. Excess Water drained & hence wastage of water2. Energy loss due to drain control 3. Mechanical wear & tear

Present System : Water outlet controlled by varying the speed of AC motor using V.F.D.

Freq

(Hz) Amp. kW 3Water m / hr. Drain Valve

Previous System 50 100 60 130 50 to 70 open

Present System 25 to 40 40 to 50 40 130 100% (Average)

106

Energy Saving

3Actual capacity of 100 kW motor : 500 m /hr 3Actual requirement for process : 130 m /hr

Without drive power consumption : 60 kWWith AC Drive power consumption : 40 kWEnergy Saving : 480 kWh/dayAnnual Saving : Rs 0.65 MillionInvestment : Rs 0.325 MillionPayback period : 5 months

3.4.3 Sample Calculations

3A) An industrial fan with measured flow rate of 90 m /s has 80 mm WC static pressure developed across it. The motor power drawn is 120 kW and motor efficiency of 86%. We first find out the fan static efficiency.

For the above fan, the bagfilter in the system was replaced with ESP (Electrostatic Precipitator). The pressure drop across the bagfilter was 65 mm WC. With ESP, pressure drop was 20 mmWC. Flow rate increased by 20%. The original flow can be obtained by two options:

a) Impeller trimming

b) Reduced RPM with pulley diameter change

For option (a), if original impeller size were 70 mm in diameter, what would be the new impeller diameter if efficiency drops by 5%?

For option (b), what would be the required reduction in RPM if fan was originally running at 850 RPM and efficiency at reduced RPM is expected to be 66%?

We finally find out the differential energy savings between the two options at 8760 hours/annum and at Rs.4 / unit.

Motor power drawn = 120 kW Power input at fan shaft (BHP) = 120 x 0.86 = 103.2 kW

3Flow, Q = 90 m /s1

Pressure developed across fan, H = 80 mm 1

Original impeller diameter (D ) = 70 mm1

Original RPM = 850 RPMFan static efficiency = Flow x Pressure developed across fan x100 102 x Power developed at fan shaft = 90 x 80 x 100

102 x 103.2 = 68 %

107

Option (a)

New Flow rate, Q = 90 x 1.223 = 108 m /hr

Pressure developed across fan, H = 80-(65-20)2

= 35 mm WCNew fan static efficiency = 68 -5 = 63%

3 3For flow Q = 90 m /s, H1 =?, Q = 108 m /s and H = 35 mm WC1 2 22 (Q / Q ) = (H /H )2 1 2 12 (108/90) = (35/H1)

2 H = (90/108) x351

= 24 mm )Power developed at fan shaft = 90 x 24 102 x 0.63 = 33.61 kWNew impeller diameter (D ) 2

Considering the fan law (D / D ) = (Q /Q ) = (N /N )1 2 1 2 1 2

D = 70 mm, Q =108, Q = 90, D = 58 mm, N = 850 RPM 1 1 2 2 1

New impeller diameter, D = 58 mm2

New RPM = 90/108 x 850 = 708 RPM

Option (b)

Efficiency at reduced RPM = 66%Power developed at fan shaft = 90 x 24 102 x 0.66 = 32.08 kWDifferential power savings = 1.53 / 0.86 x 8760 hours/annum x Rs.4 / kWh = Rs. 62340

3B) A centrifugal pump pumping water operates at 35 m /hr and at 1440 RPM. The pump operating efficiency is 68% and motor efficiency is 90%. The discharge

2pressure gauge shows 4.4 kg/cm . The suction is 2m below the pump centerline. If the speed of the pump is reduced by 50 % estimate the new flow, head and power

3Flow = 35 m /hrHead developed by the pump = 44 - (-2) = 46 m

3 3 2Hydraulic Power = Q (m /s) x Total head, hd - hs (m) x (kg/m ) x g (m /s)/1000Power drawn by the motor = (35/3600) x 46 x 1000 x 9.81

1000 x 0.68 x 0.9 (i.e. efficiency of pump & motor) = 7.2 kW

Flow at 50 % speed Q : 35 / Q = 1440/7202 2

3 Q = 17.5 m /hr22Head at 50 % speed H : 46 / H = (1440/720) 2 2

H = 11.5 m 23 3Power at 50 % speed P : 7.2/kW = 1440 / 720 2 2

P = 0.9 kW 2

108

3.5 Refrigeration & Air Conditioning System

Refrigeration systems are used for process cooling by chilled water or brine, ice plants, cold storage, freeze drying, air-conditioning systems etc. The refrigerant temperatures for process cooling applications may range from 15°C to as low as - 70°C.

Comfort air-conditioning requires refrigerant temperatures in the range of 0°C to 5°C. Air-conditioning generally implies cooling of room air to about 24°C and relative humidity of 50%-55%.

In some applications, air-conditioning involves humidification of air up to 70%-80% relative humidity (as in textile industry) or dehumidification of air to less than 20% (e.g.in some pharmaceutical industries, rooms housing sophisticated electronic equipment, storage rooms for hygroscopic materials etc.).

There are types of refrigeration system :a) Vapour Compression Systemb) Vapour Absorption System

Vapour compression machines are used extensively for refrigeration. This system requires motive power to drive a compressor, which is supplied by an electric motor or engine.

With increasing electricity prices, there is renewed interest in Absorption Refrigeration machines, wherein heat is used for cooling. Users having waste heat or economical heat energy sources are using the absorption chillers.

3.5.1 Energy Consumption in Refrigeration Systems

The cooling effect of refrigeration systems is generally quantified in tonnes of refrigeration.

1 Tonne of Refrigeration (TR) = 3023 kcal/hr = 3.51 kWthermal

= 12000 Btu/hr

The commonly used figures of merit for comparison of refrigeration systems are Coefficient of Performance (COP), Energy Efficiency Ratio (EER) and Specific Power Consumption (kW/TR). The definition of these terms are given below.

If both refrigeration effect and the work done by the compressor (or the input power) are taken in the same units (TR or kcal/hr or kW or Btu/hr), the ratio is

COP = Refrigeration Effect Work done

If the refrigeration effect is quantified in Btu/hr and the work done is in Watts, the ratio is

EER = Refrigeration Effect (Btu/hr) Work done (Watts)

Higher COP or EER indicates better efficiency.

109

The other commonly used and easily understood figure of merit is Specific Power Consumption = Power Consumption (kW)

Refrigeration effect (TR)A lower value of Specific Power Consumption implies that the system has better efficiency.

3.5.1.1 Specific Energy Consumption in Refrigeration and Air-conditioning Systems

Table 3.9 shows the figures of merit for Vapour Compression systems using reciprocating and centrifugal compressors. Table 3.10 shows the figures of merit for steam heated and also direct natural gas / LDO fired absorption chillers; here, in addition to COP and EER, the specific steam consumption in kg/hr/TR is mentioned.

Table 3.9 : COP, EER & Specific Power for Vapour Compression Systems (forochilled water at 8 C with water cooled condensers)

Note : The above data is based only on the compressor power consumption, auxiliary power for pumps, fans etc. is excluded.

Table 3.10 : COP, EER & Specific Power for Vapour absorption Systems (for ochilled water at 8 C with water cooled condensers)

Capacity TR Power kW COP EER Btu/hr/W Specific Power kW/TR

Open Type Reciprocating Compressors

10.78 6.62 5.75 19.7 0.61

32.20 21.38 5.32 18.2 0.66

48.30 32.06 5.32 18.2 0.66

64.40 42.75 5.32 18.2 0.66

Semi-hermetic Reciprocating Compressors

9.26 7.00 4.62 15.8 0.76

13.90 12.10 4.03 13.8 0.87

42.00 34.50 4.28 14.6 0.82

Open Type Centrifugal Compressors

563.67 329.94 6.00 20.5 0.59

Window Air-conditioners & Split Units

1.5 1.8 to 2.3 2.9 to 2.3 7.8 to 10 1.2 to 1.5

Capacity TR Steam pressure kg/cm2

Steam cons. K=Kg/hr.

COP EER Btu/hr/W

Specific steam cons. Kg/hr/TR

Single Effect Chiller (Steam heated) 240 3.0 2101.0 0.61 2.10 8.75

Double Effect Chiller (Steam heated) 100 8.0 490.2 1.10 3.76 4.90155 8.0 736.5 1.13 3.86 4.75270 8.5 1284.0 1.13 3.86 4.76500 8.0 2296.0 1.17 4.00 4.59

Double Effect Chiller (Direct fired) 78 - 327.3 m /hr

natural gas 0.96 3.28 0.35

m3/hr/TR150 - 54.6

lit/hr LDO 0.96 3.27 0.36

lit/hr/TR

110

Comments :

a) Well designed and well maintained vapour compression systems, using reciprocating compressors, for chilled water at about 8°C have COP of 4 to 5.8, EER in the range of 14 to 20 Btu/hr/W and Specific Power Consumption in the range of 0.61 to 0.87 kW/TR. It may be noted that Open-type compressors are more efficient than semi-hermetic compressors.

b) Centrifugal compressors, which are generally used for cooling loads about 150 TR, can have COP of about 6, EER greater than 20 and Specific Power Consumption of 0.59 kW/TR.

c) Double Effect Absorption chillers at about 8°C have COP in the range of 1 to 1.2, EER in the range of 3.3 to 4 Btu/hr/W. The Specific Steam Consumption of double effect machines is in the range of 4.5 to 5.25 kg/hr/TR, at a steam pressure of 8 to 8.5 bar. The specific fuel consumption figures of directly fired

3double effect chillers are 0.35m /hr/TR (natural gas) and 0.36 lit/hr/TR (LDO). In comparison with compression system, it can still save energy cost if waste heat or any other cheaper alternative fuel is available.

The system efficiency of both vapour compression and absorption systems is critically dependent on the performance of the heat exchangers i.e. evaporator, condenser and cooling tower. Any deterioration in these equipment leads to huge energy penalties.

3.5.2 Energy Saving Opportunities

(a) Avoid Refrigeration & Air-conditioning to the Extent Possible

• Use Evaporative Cooling for Comfort Cooling in Dry Areas :• Use Cooling Tower Water at Higher Flows for Process Cooling :

Table 3.11 : Effect of Evaporator and Condenser Temperatures on Refrigeration Machine Performance

Condens er Temperature oC

Evaporator Temperature

oC

Capacity

+35 +40 +45 +50

Capacity (TR) 151 143 135 127

Power cons. (kW) 94 102.7 110.6 117.8

+5

Sp.Power (kW/TR) 0.62 0.72 0.82 0.93

Capacity (TR) 129 118 111 104

Power cons. (kW) 90 96.8 103 108.9

0

Sp.Power (kW/TR) 0.70 0.82 0.93 1.05

Capacity (TR) 103 96 90 84

Power cons. (kW) 84.2 89.6 94.7 99.4

-5

Sp.Power (kW/TR) 0.82 0.93 1.05 1.19

111

(b) Operate at Higher Temperature

oThe approximate thumb rule is that for every 1 C higher temperature in the evaporator, the specific power consumption will decrease by about 2% to 3%.

(c ) Accurate Measurement and Control of Temperature

When the refrigeration system's cooling capacity is significantly more than the actual cooling load, expansion valve control based on superheat sensing often leads to supercooling, resulting in an energy penalty due to unnecessarily lower temperature and also lower COP at lower temperatures.

(d) Reduce Air-conditioning Volume and Shift Unnecessary Heat Loads

• Unnecessary heat loads may be kept outside air-conditioned spaces. • Use False Ceilings• Use Small "Power Panel" Coolers• Use Pre-Fabricated, Modular Cold Storage Units

(e) Minimise Heat Ingress

• Check and Maintain Thermal Insulation• Insulate Pipe Fittings & Flanges • Use Landscaping to the Reduce Solar Heat Load• Reduce Excessive Window Area• Use Low Emissivity (Sun Control) Films• Use Low Conductivity Window Frames• Provide Insulation on Sun-Facing Roofs and Walls.• Provide Evaporative Roof Cooling• Use Doors, Air-Curtains, PVC Strip Curtains• Use High Speed Doors for Cold Storage

(f) Using Favourable Ambient Conditions

• Use Cooling Tower Water Directly for Cooling in Winter• Design New Air-conditioning Systems with Facility for 100% fresh air

during winter • Use Ground Source Heat Pumps

(g) Use Evaporators and Condensers with Higher Heat Transfer Efficacy

• Use Heat Exchangers with Larger Surface Area1°C higher temperature in the evaporator or 1°C lower temperature in the condenser can reduce the specific power consumption by2 to 3%.

• Use Plate Heat Exchangers for Process and Refrigeration Machine Condenser Cooling

o oPlate heat exchangers have a temperature approach of 1 C to 5 C insteado oof around 5 C to 10 C for shell and tube heat exchangers.

• Avoid the Use of Air Cooled Condensers for large cooling loads .• Use evaporative Pre-coolers for Air-cooled Condensers

112

Case Study 33 : Replacement of Existing Evaporator with a New Evaporator with Better Heat Transfer Efficacy

Brief

After achieving the saving by reduction in speed of compressors, a decision was taken to replace the existing "Ammonia Evaporator Coil in Tank" with "Shell & Tube Heat Exchanger". The comparative measurements are as follows.

Energy Saving

Annual savings : 18371 kWhAnnual savings : Rs. 82670Investment : Rs. 0.12 MillionPayback period : 1.5 years

3.5.2.1 Energy Saving Opportunities in Normal Operation

• Use Building Thermal Inertia• Put HVAC Window Air Conditioners and Split Units on Timer or

Occupancy Sensing Control• Interlock Fan Coil Units in Hotels with Door Lock or Master Switch• Improve Utilisation Of Outside Air.• Maintain Correct Anti-freeze Concentration• Install a Control System to Co-ordinate Multiple Chillers.• Permit Lower Condenser Pressures during Favourable Ambient

Conditions.• Optimise Water/Brine/Air Flow Rates• Defrosting : The most widely used methods for defrosting are:

1. Shutting down the compressor, keeping the fan running and allowingthe space heat to melt the frost.

2. Using out side warm air to melt the frost after isolating the coil from the cold room.

3. Using electric resistance heaters in thermal contact with the coil.4. Bypass the condenser and let the hot gas into the evaporator to melt the frost.5. Spray water on the coils to melt the frost.

• Match the Refrigeration System Capacity to the Actual Requirement • Monitor Performance of Refrigeration Machines

3.5.2.2 Maintenance to Ensure Energy Efficient Operation

• Clean Fouled Heat Exchangers• Specify Appropriate Fouling Factors for Condensers• Do Not Overcharge Oil• Purging the Condenser of Air

Parameter Before

Implmentation

After

Implementation

Saving /

Improvement

Power consumption (kW) 39.9 32.3 7.6

Operating hrs./day 10 6.7 3.3

Energy Consumption

(kWh/day) 323 267 56

113

The methods used for air purging are :

• Direct venting of the air-refrigerant mixture, which is a primitive manualtechnique.

• A small compressor draws a sample of the refrigerant gas and compressesthe mixture, condensing as much as possible of the refrigerant, and vents the vapour mixture that is now rich in non-condensibles.

• A low temperature evaporator, in-built in the system, condenses most of the refrigerant from the refrigerant-air mixture drawn from the condensor or receive and vents the non-condensibles. This method does not require a separate compressor and is used widely.

Purging of non-condensibles plays an important role in maintaining the efficiency of refrigeration machines.

Case Study 34 : Modification in Chilled Water Pumping System

Brief

The chilled water system had primary (chiller side) and secondary (process side) pumps with a hot well and cold well arrangement. Since the chilled water requirement for the plant was reasonably steady, it was decided to eliminate the primary pump and connect the warm chilled water from the secondary side directly to the chiller, bypassing the hot well. In view of the increased pressure requirement, a new, efficient pump of appropriate head requirement was recommended. The power consumption scenario before and after this change is as follows:

Energy Saving

Case study 35 : Replacement of inefficient condensers of central AC plant of administrative building of a corporate house

Brief

In the administrative building, there are two compressors installed by a company. Each compressor is of 60 TR rating as per normal perception of the operating staff. Originally there were two 10 HP pumps for circulation of condenser cooling water and the cooling was achieved by spray nozzles. Subsequently an induced draft cooling tower was installed for condenser water cooling. Further one 15 HP pump was put in parallel to existing 10 HP pumps because of poor cooling and high discharge problem, it was thought that the water supply was inadequate. There are two independent DX coils (Air Handling Units).

Parameter Before Implementation

After Implementation

Saving / Improvement

Operating hrs. of primary pump (hrs.)

10 NIL -

Energy consumption (kWh/day) 85 NIL -

Operating hrs. of secondary pump (hrs.)

24

24

-

Energy consumption (kWh/day)

271

139

132

Total power consumption (kWh/day) 356

139

217

114

During the study the pressures, temperatures & water flow in the cooling water circuit were measured. It was observed that there was a high discharge pressure and low suction pressure due to heavy scaling in condenser.

Consequent upon study, the condensers were replaced. Valves were replaced with butterfly valves and cooling coils were cleaned. Filters of AHU units were also replaced.

Energy Saving

Annual energy saving : 21275 kWhAnnual Saving : Rs. 75,000 Investment : Rs. 0.16 MillionPayback period : 2 years

Case study 36 : Savings due to stopping bypass through idle pumps and idle condensers.

Brief

In an automobile plant, condenser water was flowing through the idle pumps and the idle condensers resulting in loss of head as the valves had broken down and were passing. By stopping by-pass though idle pumps and idle condensers the energy savings was as follows :

Energy Saving

Annual Energy Saving : 2760 kVAhAnnual Saving : Rs.979800Investment : NilPayback : Immediate

3.5.3 Cooling Towers

In many plants, after the cooling tower has been in service for a few years, the need for improving its performance is felt. This may be due to:

a) Deterioration of efficiency of the cooling tower,b) Deterioration in the efficiency of the heat exchangers (coolers, condensers

etc.) at the end-use side,c) Additional heat rejection due addition of equipment, plant capacity etc.

Two parameters, which are useful for determining the performance of cooling towers, are the Temperature Range and Temperature Approach.

3.5.3.1 General Tips to Save Energy in Cooling Towers

- Control cooling tower fans based on leaving water temperatures.- Control the optimum temperature as determined from cooling tower

and chiller performance data.- Use two-speed or variable speed drives for cooling tower fan control if the

fans are few. Stage the cooling tower fans with on-off control if there are many.

- Turn off unnecessary cooling tower fans when loads are reduced.- Cover hot water basins to minimize algae growth that contributes to

fouling.- Balance flow to cooling tower hot water basins.

115

- Periodically clean plugged cooling tower distribution nozzles.- Install new nozzles to obtain a more uniform water pattern.- Replace splash bars with self-extinguishing PVC cellular film fill.- On old counterflow cooling towers, replace old spray type nozzles with

new square spray ABS practically non-clogging nozzles.- Replace slat type drift eliminators with low pressure drop, self

extinguishing, PVC cellular units.- Follow manufacturer's recommended clearances around cooling towers

and relocate or modify structures that interfere with the air intake or exhaust.

- Optimize cooling tower fan blade angle on a seasonal and/or load basis.- Correct excessive and/or uneven fan blade tip clearance and poor fan

balance.- Use a velocity pressure recovery fan ring.- Consider on-line water treatment.- Restrict flows through large loads to design values.- Shut off loads that are not in service.- Take blow down water from return water header.- Optimise blowdown flow rate.- Send blowdown water to other uses or to the cheapest sewer to reduce

effluent treatment load.- Install interlocks to prevent fan operation when there is no water flow.- Replace ordinary Aluminium fans by more energy efficient

aerodynamically designed FRP fans (Fibre Reinforced Plastic).

Case study 37 : Replacement of existing metal (aluminum alloy) blades by FRPblades for cooling towers.

Brief

The cooling tower specification is given below:

Replace the aluminum blades by new energy efficient FRP blades. By using FRP blades there will be a minimum saving of 10% in the energy.

Savings obtained by conversion of aluminium blades to FRP blades.

Energy Saving

Actual power on cooling tower fan motor : 5.93 kWPercentage of power savings by conversion to FRP blades : 10%Working hrs/ day : 24Working days/ year : 355Tariff (Rs./unit) : Rs. 3.53Annual saving : 5.93 x 0.10 x 24 x 355 = 5,052,36 kWhAnnual saving @ of Rs 3.53/kWh : Rs.17,834Investment : Rs.10,000Payback period : 7 months

Sl.

No. Location Specification Fan M otor Rated

Power (kW) Actual

Power kW

1. Cooling Plant

Cooling tower Capacity

200 TR

11.5

5.93

116

Case study 38 : Installation of automatic temperature controller in the cooling tower systems.

Brief

0Install automatic temperature controller for cooling towers (28-30 C). The controller switches off the fan when the cold well temperature goes below the set temperature and switches on when temperature goes above the set temperature (28-

030 C).

Energy Saving

Annual Saving : Rs.137300Investment : Rs.50000Payback period : 5 months

3.6 Energy Savings in Transformers

Transformer is the most efficient equipment in an electrical system. Distribution transformers are very efficient, with efficiencies of 97% or above. It is estimated that transformer losses in power distribution networks can exceed 3% of the total electrical power generated. In India, for an annual electricity consumption of about 500 billion kWh, this would come to around 15 billion kWh.

3.6.1 Losses in Transformers

Transformer losses consist of two parts: No-load loss and Load loss1. No-load loss (also called core/iron loss) is the power consumed to sustain the

magnetic field in the transformer's steel core. Core loss occurs whenever the transformer is energized; core loss does not vary with load. Core losses are caused by two factors: hysteresis and eddy current losses. Hysteresis loss is that energy lost by reversing the magnetic field in the core as the magnetizing AC rises and falls and reverses direction. Eddy current loss is a result of induced currents circulating in the core.

2. Load loss (also called copper loss) is associated with full-load current flow in the transformer windings. Copper loss is power lost in the primary and secondary windings of a transformer due to the ohmic resistance of the windings. Copper loss varies with the square of the load current. (P = I²R)

For a given transformer, the manufacturer can supply values for no-load loss, PNO-

LOAD, and load loss, PLOAD. The total transformer loss, PTOTAL, At any load level can then be calculated from:

PTOTAL = PNO-LOAD + (%Load/100)² x PLOAD

Where transformer loading is known, the actual transformers loss at given load can be computed as:

= No load loss + x (full load loss)

Parameter Before Implementation

After Implementation Saving/ Improvement %

Annual Power Consupmtion (kWh)

114423 80096 30%

kVA Load Rated kVA

2

117

3.6.2 Transformer Operation

3.6.2.1 Variation of losses during operation

The losses vary during the operation of a transformer due to loading, voltage changes, harmonics and operating temperature.

Case Study 39: Parallel operation of transformers in a Tea Industry

Brief

Energy Audit for Tea Factories making C.T.C. Tea, was conducted. Power is received at 22 kV and 11 kV by separate lines. This is stepped down by two 500 kVA Transfromer 22 kV/433V which feeds segregated loads.

The typical loss figures for 500 kVA transformers are 1660 W for no load and 6900W as load losses for 100% load. It was recommended to parallel both transformers for a total 500 kVA load on secondary side. Also, cut off one transformer from H.V. side in lean season and holidays when the load is 5% to below 25%.

Calculations

For total load of 500 kVA, there are three options.

a) Only one transformer takes full 500 kVA Load.2Losses = 1 . 66 ( No L oad) + ( 500 /500 ) x 6 . 9 k W ( l oad l osses )=8.56 kW

b)One transformer takes segregated 300 kVA while second takes 200 kVA segregated load.

2 2Losses = 1 . 66 + ( 300 /500 ) x 6 . 9 + 1 . 66 + ( 200 /500 ) x 6 . 9 k W=6.90 kW

c) Both are paralleled to take 250 kVA each.

2Losses = 2 (1.66 + (250/500) x 6.9) kW= 6 .77 kW.

Thus on major load, the losses are minimum by paralleling both transformers.

Operation at part load during lean season :

a) Two paralleled transformers

2Losses = 2 { 1 . 66 + ( 0 . 25 /2 ) x 6 . 9 } = 3 . 54 k W at 25 % load2Losses = 2 { ( 1 . 66 ) + ( 0 . 05 /2 ) x 6 . 9 } = 3 . 33 k W at 5 % load

b) Only one transformer is energized

2Losses = 1 . 66 x ( 0 . 25 ) x 6 . 9 = 2 . 09 k W at 25 % load2Losses = 1 . 66 x ( 0 . 05 ) x 6 . 9 = 1 . 68 k W at 5 % load

Thus losses are minimum at low loads using only one transformer .

The tariff was kVA of M. D. x R s . 60 + R s . 0 . 89 x k Wh + R s . 150 meter rent.

The total annual consumption for the factory was 1.85 Million kWh per year and the electricity bill was Rs 2.04 Million giving Rs 1.10/kWh as average cost.

118

Energy saving

Annual energy saving : 1000 kWhAnnual saving : Rs.10000Investment : NilPayback period : Immediate

3.6.2.2 Energy Saving by optimum -utilisation of transformers

Table 3.12 summarises the variation in losses and efficiency for a 1000 kVA transformer and also shows the difference in losses by using a 1600 kVA transformer for the same. The 1000 kVA transformer has a no load loss of 1700 watts and load loss of 10500 Watts at 100% load. The corresponding figures for 1600 kVA transformer are 2600 Watts and 17000 Watts respectively. Loading is by linear loads. Temparatures assumed equal.

Table 3.12 : Comparison of transformer losses

The efficiency of 1000 kVA transformer is maximum at about 40% load. Using a 1600 kVA transformer causes under loading for 1000 kW load. The last column show the extra power loss due to oversized transformer. As expected, at light loads, there is extra loss due to dominance of no load losses. Beyond 50% load, there is saving which is 2.96 kW at 1000 kW load.

The saving by using a 1600 kVA transformer in place of a 1000 kVA transformer at 1000 kW load for 8760 hours/annum is 25930 kWh/year @ Rs .5.0/kWh, this is worth Rs 0.129 Million. The extra first cost would be around Rs 1.5 Million. Hence deliberate oversizing is not economically viable.

3.6.2.3 Reduction of losses due to improvement of power factor

Transformer load losses vary as square of current. Industrial power factor vary from 0.6 to 0.8. Thus the loads tend to draw 60% to 25% excess current due to poor power factor. For the same kW load, current drawn is proporational to kW/pf. If p.f. is improved to unity at load end or transformer secondary, the saving in load losses is as under.

TRANSFORMER-11000 kVA, No load losses = 1700 W

TRANSFORMER-21600 kVA. No load

losses = 2600 W

Difference

in losses,

W

Per unit

Load

Load

losses Total

losses Output

kW Efficiency

% Load

losses, W Total

losses,

W

0.1 105

1805

100

98.23

60

2660

861

0.2 420

2120

200

98.9 5

265

2865

745

0.4 1680

3380

400

99.16

1062

3662

282

0.6 3780

5480

600

99.09

2390

4990

-490

0.8 6720

8420

800

98.96

4250

6850

-1570

1.0 10500

12200

1000

98.18

6640

9240

-2960

119

Saving in load losses =

2(Per unit loading as per kW) x Load losses at full load x

Thus, if p.f. is 0.8 and it is improved to unity, the saving will be 56.25% .

Case study 40 : Reallocation of the load of transformer

Brief

Presently there are 3 numbers of transformers in a plant. From the data given it can be seen that Transformer No.3 i.e. 1250 kVA transformer is loaded only 28.70% i.e. 359 kVA against 1250 kVA. It is recommended to shift the load to a lower capacity transformer of 750 kVA which is lying idle.

Transformer Loading:

Savings obtained by reallocating transformer No.3 load to idle transformer:

Calculations

Existing average load = 358.87 kVAExisting transformer No.3 rating = 1250 kVAPercentage loading of TR : 3 = 28.70%Recommended Transformer rating with respect = 750 kVAto average load

2Copper loss for existing 1250 kVA transformer = (0.2870) x 6 x 24 x 330 = 3914 kWh= 0.59 kW

(where 6 kW = full load copper loss of existing 1250 kVA transformer-considering 330 days 24 hrs operation in a year)

Iron loss for 1250 kVA transformer = 2.5 x 24 x 365 = 21900 kW(Where 2.5 kW = iron loss for1250 kVA transformer)

Total loss for 1250 kVA transformer = 21900 + 3914 kWh= 25814 kWh

On replacement of 1250 kVA transformer with750 kVA transformer, the average loading of 750 kVA transformer will be = 359 = 47.85%

7502Copper loss for 750 kVA transformer =(0.4785) x 4 x 330 x 24

= 7255 kWh(where 4 kW = full load copper loss of 750 kVA transformer-considering operating hours – 24 for 330 days)

Iron loss for 750 kVA transformer = 1.95 x 365 x 24 = 17082 kWh

(where 1.95 kW = iron loss for 750 kVA transformer)

Total losses for 750 kVA transformer = 7255 + 17082= 24337 kWh

2 1 pf [( ) ]- 1

Transformer Rated kVA

Voltage Current Loading kVA Loading %

1 2000 440 1200 914.94 45.722 2000 440 1280 953.29 47.663 1250 440 471 358.87 28.704 750 440 - - Idle

120

Energy Saving

Savings in kWh = 25814 – 24337 = 1477 kWh

Annual Savings @ Rs.4.20 per kWh =1477 x 4.20= Rs. 6203

Case study 41: Operating the two transformers in parallel to reducetransformer losses.

Brief

Power is received from the electricity board and 3 nos. of 10000 kVA, 33kV/ 433 volts transformer are installed for stepping it down to 433 volts for plants distribution. Each transformer feeds its own P.C.C. and facility is available to run the transformer in parallel.

Now the transformers are run independently and the loads in them are not balanced. The load on the T.R. 2 and 3, which were in service, was monitored for 24 hrs.

These transformers have their maximum efficiency at 25 to 50% of loading. As per monitoring, transformer 3 is loaded around 50% and transformer 2 is loaded at less than 25% of their respective rated capacities both operating outside their maximum efficiency ranges.

These transformers were run in parallel.

Energy Saving

Total losses before parallel operation : 75.2 kW Total losses after parallel operation : 64.5 kW Energy saving by parallel operation : 4035 kWh Monetary saving/yr. : Rs.14,204 Operation : 24. x 365 hrs Load on each transformer in day time : 66% - 77%Load on each transformer in night time : 15% - 20%Investment : NilPayback period : Immediate

Case study 42 : Power saving by optimizing transformer operation in largeGovernment building

Brief

One transformer is dedicated to one separate annexe building, the other 4 nos are connected in the configuration of 2 each on east and west wing of the buildings. Switching off one transformer each on west and east wing load during weekly off days and transferring the load on the other transformers in line shall save the the no-load losses of the transformer & the maximum efficiceny of the other 2 transformers can be attained by loading at 40-50 % load.

Energy Saving

Energy Saving per hour : 2kWTotal energy saving : 13,000 kWh

121

Monetary saving : Rs.52,000Investement : NilPayback period : Immediate

3.7 Energy Savings in Lighting

Lighting energy consumption contributes to 20 to 45% in commercial buildings and about 3 to 10% in industrial plants. Most industrial and commercial energy users are aware of energy savings in lighting systems. Significant energy savings can be realized with a minimal investment of capital and common sense.

Table 3.13 : Recommended lighting levels

(Source : CIE, IES)Indian standards IS 3646 & SP-32 describes the illuminance requirements at various work environments in detail.

3.7.1 Energy Saving Opportunities

3.7.1.1 Use Natural Day Lighting

The utility of using natural day lighting instead of electric lighting during the day is well known, but is being increasingly ignored especially in modern air-

Illuminance level (lux)

Examples of Area of Activity

20

Minimum service illuminance in exterior circulating areas, outdoor stores , stockyards

50 Exterior walkWays & platforms.

70 Boiler house.

100 Transformer yards, furnace rooms etc.

General Lighting for rooms and areas used either infrequently and/or casual or simple visual tasks

150 Circulation areas in industry, stores and stock rooms.

200 Minimum service illuminance on the task.

300 Medium bench & machine work, general process in chemical and food industries, casual reading and filing activities.

450 Hangers, inspection, drawing offices, fine bench and machine assembly, colour work, critical drawing tasks.

General lighting for interiors

1500 Very fine bench and machine work, instrument & small precision mechanism assembly; electronic components, gauging & inspection of small intricate parts (may be partly provided by local task lighting)

Additional localised lighting for visually exacting tasks

3000 Minutely detailed and precise work, e.g. Very small parts of instruments, watch making, engraving.

122

conditioned office spaces and commercial establishments like hotels, shopping plazas etc. Industrial plants generally use daylight in some fashion, but improperly designed day lighting systems can result in complaints from personnel or supplementary use of electric lights during daytime.

Light pipe: This is a reflective tube that brings clean light from the sky into a room, no need for lighting or incandescent bulbs. These are aluminium tubes having silver lining inside. One 13" light pipe can illuminate about 250 sq.ft of floor area with an illuminance of 200 lux. A 9" dia pipe can give the same iilluminance over a 100 sq.ft area.

A 4 ft length of light pipe of the above size provides a daytime average of 750 watts worth of light in June, 250 watts in December. If the pipe length increases to 20 ft, 50% of the light reaches the surface. These are expensive, costing between 150 to 250 dollars and is one of the emerging technologies in day lighting.

Case study 43 : Installation of solar energy systems in canteen/guest houses

Brief

Solar water heaters in canteen were installed in place of electric heaters. By installing these heaters, at least 8 months in an year, solar energy could be used. Existing heaters were retained for supplementing these units in case of bad weather or rainy season.

Energy Saving

Annual saving : 0.216 Million kWhAnnual saving : Rs. 0.68 MillionInvestment : Rs. 0.45 MillionPayback period : 8 months

3.7.1.2 De-lamping to reduce excess lighting

De-lamping is an effective method to reduce lighting energy consumption. In some industries, reducing the mounting height of lamps, providing efficient luminaires and then de-lamping has ensured that the illuminance is hardly affected. De-lamping at empty spaces where active work is not being performed is also a useful concept.

3.7.1.3 Task Lighting

Task Lighting implies providing the required good illuminance only in the actual small area where the task is being performed, while the general illuminance of the shop floor or office is kept at a lower level; e.g. Machine mounted lamps or table lamps.

3.7.1.4 Selection of High Efficiency Lamps and Luminaires

Details of common types of lamps are summarised in table 3.14 below. From this list, it is possible to identify energy saving potential for lamps by replacing with more efficient types.

123

Table 3.14 :Information on Commonly Used Lamps

Source : Best Practice Manual-Lighting : MEDA

Lamp Type Lamp Rating in Watts (Total Power including ballast losses in Watts)

Efficacy (including ballast losses, where applicable) Lumens/Watt

Color RenderingIndex

LampLife(hrs)

General Lighting Service (GLS) (Incandescent bulbs)

15,25,40,60,75,100,150,200, 300,500 (no ballast)

8 to 17 100 1000

Tungsten Halogen (Single ended)

75,100,150,500,1000,2000 (no ballast)

13 to 25 100 2000

Tungsten Halogen (Double ended)

200,300,500,750,1000,1500, 2000 (no ballast)

16 to 23 100 2000

Fluorescent Tube lights (Argon filled)

20,40,65 (32,51,79)

31 to 58 67 to 77 5000

Fluorescent Tube lights (Kryptonne filled)

18,36,58 (29,46,70)

38 to 64 67 to 77 5000

Compact Fluorescent Lamps(CFLs) (without prismatic envelope)

5, 7, 9,11,18,24,36 (8,12,13,15,28,32,45)

26 to 64 85 8000

Compact Fluorescent Lamps(CFLs) (with prismatic envelope)

9,13,18,25 (9,13,18,25) i.e. rating is inclusive of ballast consumption

48 to 50 85 8000

Mercury Blended Lamps 160 (internal ballast, rating is inclusive of ballast consumption)

18 50 5000

High Pressure Mercury Vapour (HPMV)

80,125,250,400,1000,2000 (93,137,271,424,1040,2085)

38 to 53 45 5000

Metal Halide Lamps (Single ended)

250,400,1000,2000 (268,427,1040,2105)

51 to 79 70 8000

Metal Halide Lamps (Double ended)

70,150,250 (81,170,276)

62 to 72 70 8000

High Pressure Sodium Vapour Lamps (HPSV)

70,150,250,400,1000 (81,170,276,431,1060)

69 to 108 25 to 60 >12000

Low Pressure Sodium VapourLamps (LPSV)

35,55,135 (48,68,159)

90 to 133 -- >12000

124

Table- 3.15 Summarises the replacement possibilities with the potential savings.

Table 3.15: Savings by Use of More Efficient Lamps

(Source : Website of Bureau of Energy Efficiency)

Case study 44: Replacement of Incandescent lamps and blended mercuryvapor lamps by compact fluorescent lamps (CFL)

Brief

The lighting conversion efficiency of the incandescent lamp is 13.8 lumens per watt which is very low. Blended mercury vapor lamps of 160 W installed had much higher luminous intensity than required. Blended lamps were very inefficient and the lighting conversion efficiency was only 18 lumens per watt. Replaced incandescent and blended type mercury vapor lamps with CFL.

Energy Saving

Annual energy saving : Rs. 2.07 MillionInvestment : Rs. 1.24 MillionPayback period : 8 months

Case study 45 : Utilization of natural light by installing translucent sheets for roofs in plant.

Brief

Fluorescent lamps were used to illuminate 100 rooms even during daytime, since natural lighting was not sufficient. Plant had already installed translucent sheets in many offices and wanted to install in other offices in a phased manner. Installed translucent sheets in the roofs to utilize natural lighting. After installing translucent sheets, lamps could be switched off for 8 hrs a day.

Energy Saving

Annual Saving : Rs.21,500Investment : Rs.20000Payback period : 11 months

Lamp type

Power saving

Sector

Existing

Replace by

Watts

%

Domestic/Commercial

GLS

100 W *CFL

25 W

75

75

Industry GLS 13 W *CFL 9 W 4 31

GLS 200 W Blended 160 W 40 20

TL 40 W TLD 36 W 4 10

Industry/Commercial HPMV 250 W HPSV 150 W 100 37

HPMV 400 W HPSV 250 W 150 35

* Wattages of CFL includes energy consumption in ballasts.

125

Case study 46 : Conversion of High pressure mercury vapour lamp and Halogen lamp with High pressure sodium vapour lamp.

Brief

High pressure mercury vapour lamp of 250W & 400W capacity, halogen lamp of 500 W were used for street lighting in a manufacturing plant. 250W and 400W High pressure mercury vapour lamp used for street lighting could be replaced with 70W & 150W High pressure sodium vapour lamp respectively. 500W Halogen lamps used for street lighting and outside the factory could be replaced with 70W High-pressure sodium vapour lamp.

Energy Saving

Annual saving : Rs.97,700/-Investment : Rs.20,000Payback period : 3 months

Case study 47 : Replacement of filament type indicating lamps by LED typeindicating lamps, assuming 0.8 as load factor:

Brief

In a refractory manufacturing unit, there were 150 nos of 10 W filament type lamps for indication purpose. These used to be glowing for 24 hrs for all the days of the year. It was consuming 1.2 kW. The total energy consumed was 10512 units on yearly basis. During the energy audit, it was decided that these can be replaced by LED type lamps consuming only 1 w power. After replacement by 10 nos of 1 W LED lamps, the total consumption became of 1051 units per year. The saving annually was observed of 9461 units, resulting in monetary saving of Rs 0.43 lakh per year (Rate of Rs 4.50 per unit).

Energy Saving

Annual Saving : Rs.43,000/-Investment : Rs.15000/-Payback period : 4 months

3.7.1.5 Reduction of Lighting Feeder Voltage

Fig. 3.7 shows the effect of variation of voltage on light output and power consumption for fluorescent tube lights. Similar variations are observed on other gas discharge lamps like mercury vapour lamps, metal halide lamps and sodium vapour lamps. Table-3.16 summarises the effects. Hence reduction in lighting feeder voltage can save energy, provided the drop in light output is acceptable.

126

Fig 3.7: Effect of Voltage Variation on Fluorescent Tube light Parameters

Table 3.16 : Variation in Light Output and Power Consumption

(Source : Website of Bureau of Energy Efficiency)

Particulars

10% lower

voltage

10%

higher

voltage

Fluorescent

lamps

Light

output

Decreases by

9

%

Increases

by

8

%

Power input Decreases by 15 % Increases by 8 % HPMV lamps Light output Decreases by 20 % Increases by 20 % Power input Decreases by 16 % Increases by 17 % Mercury Blended lamps Light output Decreases by 24 % Increases by 30 % Power input Decreases by 20 % Increases by 20 % Metal Halide lamps

Light output Decreases by 30 % Increases by 30 %

Power input Decreases by 20 % Increases by 20 %

HPSV lamps

Light output Decreases by 28 % Increases by 30 %

Power

input

Decreases by

20

%

Increases

by

26

%

LPSV

lamps

Light

output

Decreases by

4

%

Decreases

by

2

%

Power

input

Decreases by

8

%

Increases

by

3

%

127

Case Study 48 : Use of lighting voltage controller to reduce lighting energyconsumption

Brief

A paper manufacturing plant has a connected lighting load of nearly 370 kW. This consists of fluorescent fittings, HPSV,HPMV & CFL lamps for plant, office and area lighting. The lighting load is fed from 3.3 kV bus by 4 nos. of LT transformers. These transformers have lighting loads apart from other loads. Each transformer is connected to a Lighting circuit Distribution box. The total actual load varies between 300 to 350 kW during night. Meters are fitted at each DB to measure power consumption.

The voltage levels at lighting DBs vary between 225 & 240 V. Lighting loads consume less power at lower voltages. The installation of lighting voltage controllers, of different kVA, on each DB brought down the lighting consumption by 20%. The output voltages were set at 210 V.

Energy Saving

No. of DB lighting circuits : 4Total Power consumption : 338 kW

After installationTotal Power consumption : 275 kW Annual Total energy savings : 0.245 Million kWhAnnual Cost savings : Rs. 0.49 MillionCost of Implementation : Rs. 1.24 MillionSimple payback period : 2 .5 years

Case study 49 : Installation of Automatic Voltage Regulator (Energy Saver) in Lighting Circuit.

Brief

The lighting to the plant was provided mainly by discharge lamps like blended mercury vapour lamps, sodium vapour lamps and fluorescent lamps. In discharge lamps, the light output is roughly proportional to the input voltage. A reduction in voltage of about 5% does not cause a proportional reduction in light output. The light output is reduced marginally by 2%, but there is a substantial reduction of about 10% in power consumption. Similarly, a higher voltage does not give proportionally higher light output, but the power consumed is substantially high.

The lighting & other electrical loads were segregated into different circuits and energy saver was connected to the lighting load only. The total lighting load worked out to 900 kW. Nearly 25% of lighting energy consumed could be saved by installing Energy Saver.

Energy Saving

Annual Energy saving : 7,68,960 kWh (considering 10% saving)Annual Saving : Rs 3.5 MillionInvestment : Rs 3.2 MillionPayback period : 11 months

128

3.7.1.6 Electronic Ballasts

Conventional electromagnetic ballasts (chokes) are used to provide higher voltage to start the tube light and subsequently limit the current during normal operation. Table-3.17 shows the approximate savings by use of electronic ballasts.

Table - 3.17 : Savings by use of Electronic Ballasts

(Source : Website of Bureau of Energy Efficiency)

Electronic ballasts have also been developed for 20W and 65W fluorescent tube lights, 9W & 11W CFLs, 35W LPSV lamps and 70W HPSV lamps. These are now commercially available.

Case Study 50: Use of Electronic Ballasts at Electrical SwitchgearManufacturing Plant

Brief

No. of electronic blasts : 24000Hours/annum operation : 2400

Energy Saving

Annual Energy Saving through electronic ballast : 8,83,200 kWhAnnual additional saving due to : 1,39,100reduced heat load on air-conditiong (kWh)Total annual energy saving : 10,22,300 kWhAnnual saving : Rs 6.29 MillionInvestment : Rs 3.6 MillionPayback period : 7 months

3.7.1.7 Low Loss Electromagnetic Chokes for Tube Lights

The loss in standard electromagnetic choke of a tube light is likely to be 10 to 15 Watts. Use of low loss electromagnetic chokes can save about 8 to 10 Watts per tube light. The saving is due to the use of more copper and low loss steel laminations in the choke, leading to lower losses.

3.7.1.8 Timers, Twilight Switches & Occupancy Sensors

Automatic control for switching off unnecessary lights can lead to good energy savings. Simple timers or programmable timers can be used for this purpose.

The timings may have to change, once in about two months, depending upon the season. Use of timers is a very reliable method of control.

Type of Lamp With Conventional Electromagnetic Ballast

Power Savings,Watts

40 W Tubelight

53

42 11

70 W HPSV 81 75 6

With Electronic Ballast

129

Twilight switches can be used to switch the lighting depending on the availability of daylight. Care should be taken to ensure that the sensor is installed in a place, which is free from shadows, light beams of vehicles and interference from birds. Dimmers can also be used in association with photo-control; however, electronic dimmers normally available in India are suitable only for dimming incandescent lamps. Dimming of fluorescent tube lights is possible, if these are operated with electronic ballasts; these can be dimmed using motorised autotransformers or electronic dimmers (suitable for dimming fluorescent lamps; presently, these have to be imported).

Infrared and Ultrasonic occupancy sensors can be used to control lighting in cabins as well as in large offices. Simple infrared occupancy sensors are now available in India. However ultrasonic occupancy sensors have to be imported.

In developed countries, the concept of tube light fixtures with in-built electronic ballast, photo-controlled dimmer and occupancy sensor is being promoted as a package.

3.7.1.9 Exterior Lighting Control

Use a lighting control panel with time clock and photocell to control exterior lighting to turn on at dusk and off at dawn and turn non-security lighting off earlier in the evening for energy savings.

Case study 51 : Installing Photo Electric Controls in identified areas to control artificial lighting

Brief

The lighting in the plant was mainly provided by fluorescent lamps. The shop areas were provided with north light in the roof which provided good lighting in the shop floor during day time when sky was clear. Apart from this, the machines were also provided with work lights. In spite of all these provisions the shop artificial lights were always switched on.

Segregated lighting and fan circuits provided distribution boards exclusively for lighting. Installed photo electric switches to switch off light in identified areas.

Energy Saving

Annual Energy saving : 43,800 kWhAnnual saving : Rs.1,57,000/-Investment : Rs.80,000/-Payback period : 6 months

Case study 52 : Providing Day Light Switches to control lamps in identified areas.

Brief

The process area of the plant was provided with enough lighting by means of Fluorescent Lamps. Fluorescent lamps were ON throughout the day. It was observed that translucent sheets were not provided in the roof.

130

Installed Day Light Switches to switch off lamps and provided translucent sheets in the roof to get natural light in daytime.

Energy Saving

Annual Energy Saving : 2,74,176 kWhAnnual saving : Rs.11,67,990Investment : Rs.68000/-Payback Period : 1 months

Case Study 53: Street lighting modifications at Municipal Corporation

Brief

Conventionally, streetlight planning in a Municipal Corporation was not systematic - it was normally quantity based and not lighting design based. Photometric & Installation terms were totally ignored and the Selection criteria for Lamps & Luminaires ignored.

The corporation realized the need for uniform & required level of illumination with increased energy efficiency. As a part of this innovation, they decided to develop street lighting on new roads in a scientific and systematic manner by implementing "Code of practice for lighting of Public thoroughfares IS 1944 (Part I & II), 1970".

During different seasons street light ON / OFF timings are changed.

• The ON time varies from 6:00 pm during winters to 7:45 pm during summers.

• The OFF time varies from 7:15 am during winters to 5:30 am during summers.

• It is necessary to fix ON / OFF timings for the entire year according to sunset and sunrise timings.

• For this purpose annual programmable time switches are preferable rather than the conventional manual ones to switch ON & OFF exactly at the required timings throughout the year.

Almost 5 to 10% savings are achieved by using annual programmable time switch.

Parameter Before Implementation

After Implementation

Pole height (m) 8.5 to 10 8.5 to 10 Meters Mounting height 7 to 8 10 Span between Poles 30 42 Over hang (m) 1.5 to 3 0.9 to 1.25 Meters Angle of Tilt (degrees) 15 5o-10o Wattage of Luminaries 250 250 No. of poles 33 22 (33% reduction) No. of HPSV lamps 66 44 Cost of Installations (Rs.) 7,57,100 5,90,000 (22%

saving) Annual Electrical Consumption (kWh)

74,500 50,100 (32.75% saving)

Average Illumination Less than10 Lux 30 Lux with 40% uniformity

131

Energy Saving

Annual Energy Saving : 24400 kWhAnnual Saving : Rs.167100Investment : Rs. 240 Million for 21 major roadsPayback period : 54 months

3.7.1.10 T5 Fluorescent Tube Light

The Fluorescent tube lights in use presently in India are of the T12 (40w) and T8 (36W). T12 implies that the tube diameter is 12/8" (33.8mm), T8 implies diameter of 8/8" (26mm) and T5 implies diameter of 5/8" (16mm). This means that the T5 lamp is slimmer than the 36W slim tube light. The advantage of the T5 lamps is that due to its small diameter, luminaire efficiencies can be improved by about 5%. However, these lamps are about 50mm shorter in length than T12 and T8 lamps, which implies that the existing luminaires cannot be used. In addition, T5 lamp can be operated only with electronic ballast.

Case Study 54 : Use of T5 fluorescent lamps in Pharmaceutical industry

Brief

Prior to the installation of T5 lamps, the administration, Clean room and R&D areas of the plant were using T8 (36W) lamps. There were about 1500 lamps altogether. The lamps were having electromagnetic ballasts which consume about 12 watts/lamp.

After consultations with the manufacturer of T5 tube lights, a deferred payment scheme was evolved where in the cost of the lamp will be repaid in 12 months. Warranty was also given for 12 months, during which if a lamp fails, free replacement is ensured. The price of one T5 lamp was Rs 875/-.

Energy Saving

Power consumption of 36w T/L : 48 W Power consumption of 28 w T5 T/L : 29 WEnergy saving per T/L : 19 WAnnual energy saving : 0.13 Million kWhAnnual savings : Rs 0.6 MillionInvestment : Rs. 1.2 MillionPayback period : 2 years

3.7.1.11 Lighting Maintenance

Maintenance is vital to lighting efficiency. Light levels decrease over time because of aging lamps and dirt on fixtures, lamps and room surfaces. Together, these factors can reduce total illumination by 50 percent or more, while lights continue drawing full power. The following basic maintenance suggestions can help prevent this.

• Clean fixtures, lamps and lenses every 6 to 24 months by wiping off the dust.• Replace lenses if they appear yellow.• Clean or repaint small rooms every year and larger rooms every 2 to 3

years. • Consider group re-lamping.

132

3.8 Towards Energy Efficient Homes

Home uses of energy constitute the following: -

• For cooking (LPG, kerosene, electricity, biogas, biomass)• For lighting (electricity, kerosene, biogas)• For heating (electricity, kerosene, coal, biomass)• For cooling (electricity, use of home gadgets)• For transportation (petrol, diesel, electricity)

3.8.1 Electricity

Consumption level of some of the commonly used household electrical appliances is given in the following table-3.18.

Table 3.18 : Electricity Consumption of Electrical Appliances

The following appliances typically can be attributed as electricity guzzlers:

• Air conditioner• Electric Water heater• Refrigerator• Washing machine• Television• Incandescent lamp• Computer

Rational Use of Energy

Rational use of energy does not mean that we sacrifice the need for comfortable existence. Rational use of energy strictly means to use the available energy more efficiently and avoid wastage of energy when a particular appliance is not in use. Energy saving potential in a typical house is 20%-25%. If the electricity bill is Rs. 2000/- p.m., one saves about Rs. 400/- p.m. by proper use of electrical appliances.

Appliances Capacity Consumption

Instant Geyser 3000 Watt 3 units/ hour Immersion Rod 1000 Watt 1 unit/ hour Air Conditioner 1500 – 2500 Watt 8.5 – 14.5 units/ day Air Cooler 170 Watt 1.7 units/ day Fan 60 Watt 0.6 unit/ day Refrigerator 200/300/500 Watt 2/3/5 unit/ day Electric Kettle 1000 – 2000 Watt 1 – 2 units/ hour Hot plate 1000 – 1500 Watt 1 – 1.5 units/ hour Oven 1000 Watt 1 unit/ hour Toaster 800 Watt 0.8 unit/ hour Iron 750 Watt 0.65 – 0.75 unit/ hour Incandescent Lamp 100/ 60/ 40 Watt 0.5/ 0.3/ 0.2 unit/ day Fluorescent Lamp 40/ 20 Watt 0.28/ 0.15 unit /day Slim Tube 36 Watt 0.26 unit/day Compact Fluorescent Lamp 7/ 9/ 11/ 13 Watt 0.06-0.09 unit/ day TV 180 Watt 0.2 unit/ hour Vacuum Cleaner 800 Watt 0.8 unit/ hour Desktop Cleaner 120 Watt 0.13 unit/ hour

133

Energy saving can be achieved in homes and our day-to-day life by adopting the following simple measures.

3.8.2 Lighting & Fans

• Use natural lighting during the day.• Replace incandescent lamps with a CFL. Payback period of CFL assuming its

cost as Rs. 110/- is less than 6 months.• Switch off the light when not in use.• Use 28W tubelight in place of 40W tubelight.• Replace the conventional choke with electronic blast.• Use electronic regulators for energy saving.• Lubricate the fans regularly.

3.8.3 Air-conditioner

• Use stabilizer with air conditioner & act the voltage to 220 V.• Clean the filters, condenser coils and thermostat at regular intervals.• Avoid frequent opening of doors and windows.• Avoid direct sunlight in the air conditioned space.• Installation of reed screens in air-conditioners.

C• Save Re. 1/- per hour by setting the room temperature to 250 .• Purchase 'Star' rated energy efficient Air Conditioners only.

3.8.4 Electric Water Heater

• Change of heating element every 5 to 6 years.0• Set the thermostat at 50 C to save power.

• Put on the water heater only 15 minutes before use.

3.8.5 Refrigerator

• Use stabilizer with refrigerator & set the voltage to 220 volt.• Check the gaskit to avoid ingress of heat from outside.• Avoid frequent opening of refrigerator door.• Do not place the refrigerator in kitchen or congested area.• Regular defrosting to avoid ice accumulation in the freezer.• Cool the food before putting it in the refrigerator.• Purchase 'Star' rated Energy Efficient Refrigerators only.

3.8.6 Washing Machine

• Using the machine at full load, the water consumption remains the same irrespective of load of clothes.

• Switch on the washing machine after loading.• Put off the machine from the main switch after use.

C• Same about 15%-20% of power by setting thermostat to 500 .

3.8.7 Television

• Switch off the TV from the main switch and not through remote control.• Don't leave TV on stand-by mode as it consumes around 80 watts of power

even when not being viewed.

135134

3.8.8 Computers

• Switch on the computer when required to be used .• Don't leave the computer in stand-by mode when not in use as in stand-by

mode, it consumes 60 watts of power (monitor plus CPU) while no useful work is being done.

3.9 Energy Audit Study Conducted by PCRA

Case Study 55 : Energy Audit of a Bank's Head Quarter building in New Delhi

Brief

Punjab National Bank- with its beginning in April, 1895 at Lahore- is at present one of the foremost banks in India with a network of 4500 offices, serving more than 3.7 crore customers and having a business turn over exceeding Rs 1,94,000 crores. The focus areas during the Energy Audit were:

1.1 Review of Electricity Bills, Contract Demand & Power Factor1.2 Study of DG Set1.3 Study of Motor Loading1.4 Study of Illumination1.5 Study of Air Conditioning System

Energy Savings

SlNo.

Equipment / ObservationReason

Expected Savingsper annum (kWh/kVAh, kL)

Expected Savingsper annum (Rs in lakh)

Expected Investment (Rs in Lakh)

PaybackPeriod

Action Required

A. Load Management:

1. Power Factor is poor and is sometimes leading

4,23,420 kVAh

20.75

4.00

3 months

-Monitor and Maintain Power Factor.

- Connect capacitors through APFC (Automatic Power Factor Controller

- Install capacitors of 800 kVAR.

B. DG Set:

1. Specific Power Generation of DG sets very low.

12 kL of HSD

3.96

Minimal

Immediate

-The engine needs service. Consult the dealer or manufacturer

C. Illumination:

1. Use of energy efficient lights

11,497 kWh

0.56

0.14

3 months

- Replacing existing

incandescent and halogen lamps with CFLs

2. Use of 28 W, T5 tube lights

2,26,000 kWh

11.07

16.00

18 months

Replacing existing 2000 nos. of tube lights with 28 W T/L having electronic chokes.

References

1. Designing with Light- A lighting Handbook - Anil Walia-International Lighting Academy

2. Handbook of Functional requirements on Industrial Buildings-SP-32- Bureau of Indian Standards

3. Energy Savings in Electric Motors : PCRA4. Energy Savings in Electric Furnaces : PCRA5. Energy Savings in Compressed Air System : PCRA6. Energy Savings in Pumps, Fans & Variable Speed Drives : PCRA7. Energy Savings in Refrigeration & Air Conditioning System : PCRA8. Energy Audit Reports of PCRA9. IS : 325 - "Three Phase Induction Motors - Specifications"10. IEC: 60034 (1to 18) - Rotating Electrical Machines11. IS : 4722 - Rotating Electrical Machines12. IS: 8789 - Values of Performance characterstics for Three-Phase Induction

Motors13. IS : 12615 - Induction Motors :Energy Efficient Three-Phase squiral cage-

speficiation14. IS : 13555 - Guide for selection & Application of Three-phase A.C. Induction

Motors for different types of driven equipment.15. NEMA MG-1 : National Electrical Mnaufacturers Association, USA16. EEMA -19 : Energy Efficeint Indution Motors - Three phase - squiral cage 17. Preformance, Selection & Application of Large A.C. Motors by Devki Energy

Consultancy Pvt. Ltd., Vodadora18. Induction Machines by P.L. Alger19. Electrical Machies by M. Mostenko20. 'Industrial Furances' (Book), E.I. Kazantsev, Mir Publishers, Moscow.21. 'Handbook of Electrical Heating for Industry': C.James Erickson, IEEE Press -

The Institute of Electrical and Electronics Engineers Inc., (IEEE), New York22. 'Efficient Use and Management of Electricity in Industry' Devki Energy

Consultancy Pvt. Ltd, Vadodara.23. 'Energy Audit Manual' (Series No.1) - 'Steel Foundary', National Productivity

Council, New Delhi.24. 'BCIRA' Publication - UK25. 'Industrial Furnaces' W.Trinks - M.H. Mawhinney - John Wiley26. 'Induction Heating Handbook' John Davies & Peter Simpson - Mcgraw Hill27. Compressed Air System - A Guidebook on Energy and Cost Saving, E.M.

Talbott, The Fairmont Press Inc., Zilburn, USA.28. Compressors-Selection & Sizing, Boyce & Brown, Gulf Publishing Co.,

Houstonne, USA

Cooling water and chilled water is flowing in idle Units.

Effectiveness of existing Units is only 64% and specific power consumption is high

1.

8,10,000 kWh 39.69 75.00

23 months

-Install Screw Chillers of total 600 TR capacity

2.

1,20,000 kWh

5.88

Nil

Immediate

-Keep the idle Units isolated by closing the appropriate valves.

D. Air Conditioning System:

136

29. 'Pump Hand Book'-I.J. Karassik, WC Krutzsch, W.H. Fraser, J.P. Messina, McGraw Hill International.

30. 'Analysis of Water Distribution Systems'- T.M. Walski CBS Publishers, Delhi.31. Refrigeration and Air Conditioning' - W.F. Stoecker and J.W. Jones - Tata

McGraw Hill.32. 'Technology Menu for Efficient Energy Use'-National Productivity Council,

India and Centre for Energy and Enviornmental- Studies of Princetonne University.

33. 'Good Practice Guide No. 2' - Energy Efficiency Office, Deptt. of Energy, U.K. 34. 'Energy Saving, with Adjustable Frequency Drive'- Allen Bradley Publication.35. Saving Electricity in Utiltiy Systems of Industrial Plants, Devki Energy

Consultacny Pvt. Ltd., Vadodara.36. Industrial Refrigeration Handbook, Wilber F. Stoeker, McGraw Hill .37. Refrigeration and Air conditioning, M. Prasad, New Age International (P) Ltd.38. ASHRAE Handbooks, ASHRAE, Atlanta, Georgia, USA.39. Cooling Tower Technology- Maintenance, Upgrading and Rebuilding, Robert

Burger, The Fairmont Press Inc., Georgia, USA40. Low-E Glazing Design Guide, Timothy E. Johnson, Butterworth Architecture.41. Best Practice Manual - Electric Motors Transformers, Lighting : MEDA.42. Energy Efficient Technologies for Industries, LBNL ,USA.43. Bureau of Energy Efficiency-Course Material for Energy Manager/Auditor.44. Websites/Product Information CDs of the following manufacturers:

1. www.energymanagertraining.com2. Cromptonne Greaves Lighting Division3. Bajaj Electricals4. GE lighting, USA5. Watt Stopper Inc, USA6. Vergola India Ltd7. Lighting reasearch centre, USA

ØChapter - 4 Refining SectorØChapter - 5 Exploration & Production ØChapter - 6 LPG Bottling PlantsØChapter - 7 Marketing Terminals/ Depots

Section 3Energy Conservation

in the Hydrocarbon sector

139

4.1 Introduction

The downstream oil sector is an extremely important part of the supply chain. Growing demand for oil products clearly means that there will be a rising volume of crude oil that needs to be refined. Moreover, the oil products demand structure will change, with the expected continued move towards lighter distillates. At the same time, driven by environmental concerns, products specifications shall be moving towards significantly cleaner products that will necessitate substantial reduction in sulphur content as well as improvements in other quality parameters. To meet these challenges, the downstream sector will require significant investments to ensure that sufficient distillation capacity is in place, supported by adequate conversion and desulphurisation, as well as other secondary processes and facilities.

Refining capacity additions have fluctuated considerably through cycles of both excess and tight capacity. In the 1970s and 1980s, the refining industry experienced periods of rapid expansion fuelled by rising demand and anticipated sustained growth. Global capacity peaked at 82 million barrels per day (mb/d) in 1981 and declined to 73-74 mb/d by the late 1980s. The 1990s and early part of this century were more balanced with regard to capacity and demand, until the consumption surge of refined products in 2004 and 2005 that created a much tighter situation in the refining sector. Regionally, the Middle East, India and China are the focus for major refining capacity expansions over the rest of this decade, accounting together for almost 8 mb/d of announced projects.

4.2 Refining sector in India

thHaving achieved the capacity additions targets of 34 MTPA of the 10 Plan (Period th2002-07), the installed capacity at the end of 11 Plan (2007-08 to 2011-2012) has

been pegged at around 241 MTPA (Table 4.1). Among the refineries expected to thcome up during the 11 Plan, the most significant is the export oriented 29 MTPA

RPL refinery at Jamnagar.

Table- 4.1 Cumulative refining capacity and capacity additions during

Eleventh Plan (by year) (MT)

Refining Sector

Chapter - 4

1 April

2007

2008

2009

2010 2011 2012

Refining Capacity

148.97 158.70 194.70 210.21 225.88 240.96

Capacity addition

9.73 36.00 15.51 15.67 15.08

141140

As on April, 2008, India with 19 refineries had a total installed refinery capacity of 149 MTPA. Of this, 105.5 MTPA capacity was in the public sector and the rest in private sector. (Table - 4.2)

Table - 4.2

The complexity of the refining sector has increased markedly since the end of the 1990s due to capacity additions and expansion of cracking units. Between 1997 and 2006, Vis breaker capacity increased from 65 to 130 kb per day, Coking capacity from 30 to 250 kb per day, Catalytic cracking capacity from 150 to 470 kb per day and Catalytic Hydro Cracking Capacity from 25 to 310 kb per day. Distillation capacity is projected to be almost doubled by 2014 to 5.2 Mb per day as a result of capacity expansion and commissioning of New Greenfields Refineries.

Refinery State Capacity MTA

Throughput (MT)

Capacity Utilization

(%) Public sector

Indian Oil Corporation Limited (IOCL)

Guwahati Assam 1.00 0.92 92.00

Barauni Bihar 6.00 5.64 94.00 Koyali Gujarat 13.70 13.71 100.07

Haldia West Bengal 6.00 5.72 95.33

Mathura Uttar Pradesh 8.00 8.03 100.38

Digboi Assam 0.65 0.56 86.15 Panipat Haryana 12.00 12.82 106.83

BRPL, Bongaigaon Assam 2.35 2.01 85.53

CPCL, Manali Tamil Nadu 9.50 9.80 103.16

CPCL, Narimanam Tamil Nadu 1.00 0.46 46.00

Total (IOCL)

60.20 59.67 99.12

Hinudstan Petroleum Corporation Limited(HPCL)

Mumbai Maharashtra 5.50 7.35 133.64

Visakhapatnam Andhra Pradesh

7.50 9.41 125.47

Total (HPCL) 13.00 16.76 128.92

Oil & Natural Gas Corporation (ONGC)

Tatipaka Tamil Nadu 0.08 0.06 75.00

MRPL, Mangalore Karnataka 9.69 12.53 129.31 Total (ONGC) 9.77 12.59 128.86 Bharat Petroleum Corporation Limited (BPCL)

BPCL, Mumbai Maharashtra 12.00 12.74 106.17

KRL, Kochib Kerala 7.50 8.17 108.93

NRL, Numaligarh Assam 3.00 2.57 85.67

Total (BPCL) 22.5 23.48 104.36

Total (public sector) 105.47 112.50 106.67 Private sector

RIL, Jamnagar Gujarat 33.00 31.80 96.36 Essar Oil, Vadinar Gujarat 10.50 6.50 61.90

Total (private sector) 43.50 38.30 88.05

Grand total All India 148.97 150.80 101.22

4.3 Oil Trade

With indigenous production stagnating at around 30 MT per annum during the last five years and the increase in demand being met through increased imports, India's self-sufficiency in petroleum products has decreased from 29.4% in 2003-04 to 25.5% in 2007-08. India imported 121.7 MT of crude and 22.7MT of petroleum products at a value of Rs. 3,50,270 Crore. As per Hydro-carbon vision 2025, almost 90% of India's crude demand shall have to be met through imports, India's net oil import is projected to increase to 3 mb/day in 2015 and 6 mb/day in 2030 while product exports are expected to reach nearly 1.6 mb/day.

The total production of petroleum products in India during 2007-08 was 149.90 MT, against domestic consumption of 129.24 MT. Since the year 2001-02, with excess production vis-à-vis in-house consumption, India became net exporter of petroleum products (Figure-4.1). In the year 2007-08, India's total export of petroleum products was 39.33 MT resulting in export earnings of Rs.1,07,603 crore (Figure-4.2). The export of petroleum products during the year were dominated by diesel (14.3 MT), followed by naphtha (9.3 MT), petrol (4.2 MT), and Fuel Oil (4.72 MT). Foreign exchange earnings from petroleum products export during the year 2007-08 constituted around 15% of the country's total export earnings, which is more than any other sector i.e. minerals, textiles or gems & jewellery etc. It is projected that by 2015, India's net product export shall reach nearly 1.6 Mb per day.

Figure -4.1 Demand- supply position of petroleum products since 2001-02

Source : PPAC (2007) and MOP&NG (2006)

0

20

40

60

80

100

120

140

160

2001/02

2002/03

2003/04

2004/05

2005/06

2006/07

2007/08

Demand Supply

143142

Energy is consumed in refineries as: -

• Direct fuel in heaters/ boilers/ GTGs

• Indirect fuel to raise steam

• To generate power through STGs

• To meet process requirement

• Steam & power for process equipments drive, utilities, illumination etc.

• Cooling water circulation

4.4.1 Specific energy consumption in Indian refineries

Amongst the 19 refineries in Public and Private Sector, Reliance refinery is India's most energy efficient in terms of the Energy Intensity Index*. Reliance ranks in the top 5% of worldwide refineries, with an EII of 64 in 2002, and it ranked highest of all participating refineries in the Shell Benchmark of energy and loss performance. Table - 4.4 shows the performance of PSU, Indian refineries in terms of their MBN rating (excluding the Reliance refinery, which does not report an MBN index).

However, energy consumption per unit of input, is a misleading indicator of the energy performance of refineries as it does not account for differences in complexities, output slates or type of crude processed. A simple topping unit, for example, will always have a lower specific energy consumption than a complex refinery- sometimes one-fourth as much- but may not be able to produce blended gasoline or to remove sulfur from final products. In India, the energy performance of refineries is expressed in terms of specific energy consumption, measured as 1000 BTUs per barrel per Energy Factor (MBTU/Bbl/NRGF). This unit, commonly referred to as MBN, was developed by the Centre for High Technology (sponsored by the Ministry of Petroleum & Natural Gas) to provide a comparable basis to compare energy performance of refineries of different configurations by accounting for the throughput of secondary units.

4.4.2 Secondary Processing Units in Indian Refineries

Comparing the ratio of primary upgrading capacity to crude distillation i.e. cracking to distillation ratio, Indian refineries are relatively simple. Most large refineries in India have a cracking to distillation ratio of less than 40%, the only exceptions being the Reliance Refinery (59%) and Panipat Refinery (55%), that meet the average of the US Refinery Industry (56%). Higher cracking to distillation ratio facilitate refineries the flexibility to process lighter to very heavy crudes.

4.4.3 Refinery fuel use and losses

As can be seen from Table-4.5, aggregate refinery fuel use and losses have increased over the years as refinery throughput has expanded and new upgrading units have been brought on line. To process less expensive, heavy and higher sulphur crude to meet the domestic demand pattern, it would be necessary to expand the secondary cracking facilities of less complex refineries.

* The Solomon's EII is a unit-by-unit bench marking methodology that adjusts the unit consumption energy coefficients for process units based on feedstock or operational parameters.

Figure -4.2 Earnings from export of petroleum products

Source : PPAC (2007)

4.4 Energy Consumption in Refining Industry

Petroleum refining industry in India is one of the major energy users, consuming around 7.5% of the total energy consumed by the industrial sector. Energy use in a refinery varies due to changes in the type of crude processed, the product mix, the complexity of refinery as well as the sulfur content requirement of the final products. Furthermore, operational factors like capacity utilization, maintenance practices, as well as the age of the equipment affect energy use in a refinery.

The major energy consuming processes in a refinery are crude distillation, followed by the hydrotreater, reforming, and vacuum distillation. This is followed by a number of processes consuming a somewhat similar amount of energy, i.e., thermal cracking, catalytic cracking, hydrocracking, alkylate and isomer production.

Total energy consumption in Indian refineries during the year 2007-08, was about 316 Trillion Btu or about 2.1 Trillion Btu per million tonne of crude oil throughput. During the five years period, between 2002-03 and 2006-07, while the refinery throughput rose by 28%, the corresponding increase in energy demand shotup by nearly 52%. This increase in energy consumption was due in part to the refinery capacity expansion but mainly it was due to the addition of energy intensive secondary processing units to improve fuel quality to meet Euro III & Euro IV norms for transport fuels and also to reduce the bottom of the barrel by producing value added products. However, the energy consumption per million tonne of crude throughput has reduced marginally in the year 2007-08, due to energy efficiency improvement programmes aggressively taken up by various refinery units (Table - 4.3).

Table - 4.3: Energy Consumption in Indian Refineries

Source: CHT

Year

2002-03

2003-04

2004-05

2005-06

2006-07

2007-08

Throughput (MT)

110.582

118.680

124.304

126.986

141.463

150.806

Total Energy Consumed

(TBtu)

202.558

239.204

251.437

274.113

308.002

316.506

Consumption per tonne of throughput(TBtu/MT)

1.832

2.016

2.023

2.159

2.177

2.099

% change over the previous

year

-

+10.04

+ 0.35

+ 6.70

+ 0.83

- 3.60

0

20

40

60

80

100

120

2001/02 2002/03 2003/04 2004/05 2005/06 2006/07 2007/08

Va

lue

in R

s. L

akh

La

khs

145144

Table- 4.5 Refinery Throughput and Output (1000 tonnes per year)

* This includes external fuels used such as natural gas etc.

Table 4.4 Energy Performance of Indian Refineries (1000BTU/Bbl/NRGF)

Source : CHT

4.5 Energy Efficiency opportunities in Petroleum Refineries

A large variety of opportunities exist within petroleum refineries to reduce energy consumption while maintaining or enhancing the productivity of the plant. Studies by several companies in the petroleum refining industry have demonstrated the existence of a substantial potential for energy efficiency improvement in almost all facilities. Competitive benchmarking data indicate that most petroleum refineries can economically improve energy efficiency by 10-20%.

Major areas for energy efficiency improvement are utilities (30%), fired heaters (10%), process optimization (15%), heat exchangers (15%), motor and motor applications (10%), and other areas (10%). Of these areas, optimization of utilities, heat exchangers, and fired heaters offer the most low investment opportunities, while other opportunities may require higher investments.

Energy efficiency in refining sector can be divided into three broad categories i.e.

• Process specific

• Utilities related

• Generic

2007-08

77.44

69.34

68.52

69.33

67.08

92.06

61.31

92.26

86.83

70.48

87.25

73.55

138.85

90.64

66.15

61.55

70.73

2006-07

77.21

72.95

73.03

71.13

66.8

92.49

68.07

90.41

87.56

70.47

93.06

73.75

130.57

91.39

71.2

63.5

73.55

2005-06

77.67

71.91

75.00

76.42

69.19

92.37

66.76

94.62

94.39

78.19

95.50

77.17

167.29

92.47

70.53

65.27

76.43

2004-05

81.68

74.07

78.86

80.35

76.42

98.83

68.81

95.29

99.39

95.98

94.80

84.86

154.21

94.26

72.22

65.07

81.09

2003-04

104.79

77.69

69.89

87.87

75.37

151.16

69.19

91.18

99.85

94.46

92.00

97.66

139.81

93.39

81.39

66.69

81.85

Refinery

IOCL-Guwahati

IOCL-Barauni

IOCL-Gujarat

IOCL-Haldia

IOCL-Mathura

IOCL-Digboi

IOCL-Panipat

HPCL-Mumbai

HPCL-Visakh

BPCL-Mumbai

BPCL-Kochi

CPCL-Manali

CPCL-CBR

BRPL

NRL

MRPL

Industry average

2004-05

124304

5578.4

14219.6

11057.5

2007.9

226.5

5197.2

9042.8

1385.2

525.2

645.8

14814.5

3159.9

56.1

3346.9

373.7

118444.9

9312.9

2005-06

126986

5532

14493

8308

4091

212

6219

8862

944

40664

1649

676

14118

3182

54

3575

1224

119911

10069

2006-07

141463

6359

16730

12423

41532

187

7850

8477

803

53666

626

967

15524

3791

62

3838

1761

136074

11691

Aviation Turbine Fuel

Throughput

Light Distillates

LPG

Naphtha

Motor Gasoline

Others

Middle Distillates

MTO

(Jet Kerosene)

Kerosene

Light Diesel Oil

High Speed Diesel

Others

Heavy Distillates

Lubricants

Fuel Oil

Petroleum Coke

Paraffin Wax

Bitumen

Others

Total products

* Gross Refinery Fuel & Loss

2003-04

118680

5362

11046

11211

4393

244

4302

9948

1628

43129

486

666

13355

2739

50

3379

1304

113244

8894

2007-08

150806

6743

16470

14129

3154

186

8915

7867

713

58467

891

855

15957

4124

66

4450

2772

145793

12274

147146

Table 4.6 provides access keys by process and utility system to the description of the energy efficiency opportunities. For individual refineries, actual payback period and energy savings for the measures will vary, depending on plant configuration and size, plant location, and plant operating characteristics.

Table 4.6 Energy Efficiency opportunities in petroleum refineries. For each major process in the refinery (in rows) the applicable categories of energy efficiency measures are given (in columns).

Note : "X" indicates that relevant energy efficiency measures are possible in these areas. Lighting and boilers, used throughout refineries, are all included under Utilities.

Process

En

erg

ym

an

ag

em

en

t

Co

ge

ne

rati

on

Ga

sE

xp

an

sio

nT

urb

ine

s

Hig

hT

em

pe

ratu

reC

og

en

era

tio

n

Ga

sif

ica

tio

n

Fla

reG

as

Re

co

ve

ry

Po

we

rR

ec

ov

ery

Bo

ile

rs

Ste

am

Dis

trib

uti

on

Pro

ce

ss

Inte

gra

tio

n

Pro

ce

ss

He

ate

rs

Dis

till

ati

on

Hy

dro

ge

nM

an

ag

em

en

t

Mo

tors

Lig

hti

ng

Oth

er

Op

po

rtu

nit

ies

Desalting X

CDU X X X X X X X X VDU X X X X X X X X Hydrotreater

X

X X X X X X X

X

Cat. Reformer

X

X

X

X X

X

X

X

X

X

FCC X

X

X

X

X

X

X

X

X

X

Hydrocracker

X

X

X

X

X

X

X

X

X

X

Coker X

X

X

X

X

X

X

X

X

Visbreaker

X

X

X

X

X

X

X

X

X

Alkylation

X

X

X

X

X

X

Hydrogen X X X X X X X X

Utilities X X X X X X X X X X X X X

• PROCESS SPECIFIC

4.5.1 Desalting

The principle of desalting is to wash the crude oil or heavy residues with water at high temperature and pressure to dissolve, separate and remove the salts and solids. Crude oil may contain varying quantities of inorganic compounds such as water soluble salts, sand, silt, rust particles and other solids, together characterized as bottoms sediment. The salt in the crude is primarily in the form of dissolved or suspended salt crystals in water emulsified with the crude. These impurities, especially salts, could lead to fouling and corrosion of heat exchangers (crude preheaters) and especially the crude distillation unit overhead system. Salts are detrimental to the activity of many of the catalysts used in the downstream conversion processes and sodium salts stimulates coke formation in furnaces.

The water phase from the overheads crude distillation unit and other used water streams are normally fed to the desalter as washwater. Efforts are made in the industry to minimize water content of the crude to less than 0.3% and bottoms sediments to less then 0.015%. The concentration of inorganic impurities in the cleaned stream are highly dependent on the design and operation of the desalter as well as the crude source.

The quantity of inorganic impurities in the crude oil depends very much on the crude origin and the crude handling during transportation. The water used in crude desalting is often untreated or partially treated water from other refining process. Table 4.7 shows the typical operating conditions and water consumptions in the desalters, depending on the type of crude oil used.

Table- 4.7 Operating conditions and water consumption in the Desalters

Good Desalting Practices

I Multistage Desalters and the combined use of AC and DC fields:Multistage desalters and the combined use of AC and DC fields provide high desalting efficiencies resulting in substantial energy savings. Two-stage or even three-stage desalting is used either (if) the crude oil salt content is higher than 0.02%, or (if) the heavy residue is further catalytically processed.

ii The Benefits of this Process are;

• The dual polarity field delivers twice the voltage of an AC fields, using the same power supply/transformer requirement as an AC field.

• Because of the unchanging polarity of the DC field, water droplets respond by migrating between electrodes.

• Once water droplets approach one of the electro droplets they become charged with the same high voltage static charge that is on that plate. In a plate net charge is imparted to the water droplets causing the attraction of

Crude oil density 3kg/m (at 150°C)

Water Wash % v/v

Temp (°C)

<825 3 - 4 115 - 125825-875 4 - 7 125 - 140>875 7 - 10 140 - 150

149148

water droplets causing coalescence. The DC field forces the water droplets into coalescence course for faster coalescence. These processes are operated at a lower temperature than the conventional de-salter.

iii The lower operating temperatures mean lower fuel costs

The dual polarity Electrostatic Treater is designed to operate at temperature 0lower than a conventional electrostatic treater and upto 60 F cooler than heater

treaters. Consequently, it can process at higher viscosities, which means less heat is required to reduce the viscosity of the oil at processing conditions. It provides sizeable fuel cost for any gravity of crude oil. (For example, with 32.5° API gravity, 10,000 BOPD of crude and 1,000 BWPD of water, the dual polarity Treater achieves a savings of 1,156,250 Btu/Hr. At 60% heat results in a fuel savings of 46,250 scf/day).

iv Enhancing the oil/water separation.

Techniques applied:

I. Transfer the water effluent from desalting units to a settling drum where afurther separation between oil and water can be achieved.

II. Choosing accurate optimum interface level controllers. As a function ofspecific gravity and range of crudes processed, sensors like displacers,capacitance probes or radio wave detectors are used to control interface level.

III. A good improvement in water-oil separation can be achieved by using "wetting" agents.

IV. Use of non-toxic, biodegradable, crude specific demulsifying chemicals to promote fast coalescence of the water droplets.

v Enhance the solid/ water-oil separation

Solids entering the crude distillation unit are likely to attract more oil and produce additional emulsions and sludge. The amount of solids removed from the desalting unit should, therefore, be maximized. The objective is to minimize solids leaving the desalter with the crude oil.

Techniques Applied:

I. Use low-pressure water in the desalter to avoid turbulence.II. Replace the water jets with mud rakes. They cause less turbulence when

removing settled solids.III. The water phase (suspension) can be separated in a pressurized plate separator.

Alternatively a combination of a hydrocyclone desalter and a hydrocyclone de-oiler can be used.

IV. Evaluate the effectiveness of a sludge wash system.

vi Re-use of water for the desalter

The desalting process plays an important role in the waste water management in a refinery. The water used in other processes can be re-used in the desalter.

The following process water streams can be suitable for use as desalter wash water:

I. The accumulated water in the crude distillation unit overhead drum, usually 1-2% w/w on crude feed from steam injection.

II. The (unstripped) steam condensates from the light and heavy gas oil dryers and the vacuum distillation overhead (about 3.5% w/w on feed)

III. Stripped sour water and also other solid-free process water streams. IV. Blowdowns from cooling water and boilers.

4.5.2 Distillation CDU/ VDU

Despite the high level of heat integration and heat recovery that is normally applied, crude distillation unit remains the most intensive energy-consuming process in a refinery. In a refinery, atmospheric and vacuum distillation units account for 35-40% of the total process energy consumption followed by hydrotreating with approx. 18-20%. The various processes downstream of the CDU make use of the elevated temperatures of the product streams leaving the CDU. The number of side-streams in a high vacuum unit is chosen to maximize heat integration of producing streams at different temperatures, rather than to match the number of products required. Heat is provided by process heaters and/or by steam. Energy efficiency opportunities exist in the heating side and by optimizing the operation of distillation column. The utility requirements for the atmospheric and vacuum distillation units are given in Table 4.8.

Table - 4.8 The utility requirements for CDU

Energy Saving Opportunities in CDU/ VDU

I Optimization of Operational Parameters. The optimization of the reflux ratio of the distillation column can produce significant energy savings. The efficiency of a distillation column is determined by the characteristics of the feed. If the characteristics of the feed have changed over time or compared to the design conditions, calculations to derive new optimal operational parameters should be done to improve operational efficiency. Steam and/or fuel intensity can be compared to the reflux ratio, product purity, etc. and compared with calculated and design performance on a daily basis to improve the efficiency.

ii Checking Product Purity. Many companies tend to excessively purify products and sometimes with good reason. However, purifying to 98% when 95% is acceptable is not necessary. In this case, the reflux rate should be decreased in small increments until the desired purity is obtained. This will decrease the reboiler duties. This change will require no or very low investments (Saxena, 1997).

Unit Type

Fuel (MJ/t)

Electricity (kWh/t)

Steam consumed

(kg/t)

Cooling water (m3/t, DT=10°C)

Atmospheric 400 – 680 4 – 6 25 – 30 4.0Vacuum 400 – 800 1.5 – 4.5 20 – 60 3 – 5Note: Replacement of the steam ejectors by vacuum pumps will reduce steam consumption and waste water generation but increase the electricity consumption.

151150

iii Seasonal Operating Pressure Adjustments. For plants that are in locations that experience winter climates, the operating pressure can be reduced according to a decrease in cooling water temperatures (Saxena, 1997). However, this may not apply to the VDU or other separation processes operating under vacuum. These operational changes will generally not require any investment.

iv Reducing Reboiler Duty. Reboilers consume a large part of total refinery energy use as part of the distillation process. By using chilled water, the reboiler duty can in principal be lowered by reducing the overhead condenser temperature. A study of using chilled water in a 100,000 bbl/day CDU has led to an estimated fuel saving of 12.2 MBtu/hr for a 5% increase in cooling duty (2.5 MBtu/hr) (Petrick and Pellegrino, 1999).

v Upgrading Column Internals. Damaged or worn internals can result in increased operation costs. As the internals become damaged, efficiency decreases and pressure drop rise. This causes the column to run at a higher reflux rate over time. With an increased reflux rate, energy costs will increase accordingly. Replacing the trays with new ones or adding a high performance packing can have the column operating like the day it was brought online.

When replacing the trays, it will often be worthwhile to consider new efficient tray designs. New tray designs can result in enhanced separation efficiency and decrease pressure drop. This will result in reduced energy consumption. When considering new tray designs, the number of trays should be optimized.

vi ReVamping of CDU column. By packing CDU HGO section by suitable packing material, contact time between the vapours and condensate increases which results in improved product quality and product volume in CDU. We can achieve better distillation and lower overflash resulting in lower VDU throughput by recovering more HGO at CDU.

A Refinery in Japan achieved the following ENCON effect by packing of CDU HGO section as seen in Table 4.9.

Table - 4.9

vii Combination of GTG and CDU Furnace. Installation of GTG and utilization of GTG flue gas (550°C including 15% of oxygen) can be utilized as heat source for combustion of air for furnace resulting in low cost power production and minimizing the gas emissions.

Parameter Before After

HGO drawoff (kl/h) 10.2 22.9

2HGO sec. Liq. Load (gpm/ft ) 0.45 0.12

VDU furnace duty (Gcal/h) 28.2 25.9

Different HGO yield (%) 1.3 4.7

0900 F recovery (%) 79.7 84.7

HGO properties Ni (ppm) <0.1 <0.1

A Refinery in Japan achieved the following energy conservation in their plant by the combination of GTG and CDU Furnace as seen in Table- 4.10:

Table - 4.10

viii Reduction in CDU Operating Pressure. By reducing pressure at flash zone by 0.12 Kg/cm², temperature drop of 80°C is achieved at flash zone and temperature drop of around 120°C is achieved at furnace outlet resulting in fuel reduction of 0.3 litre/ kl.

ix Stripper Optimization. Steam is injected into the process stream in strippers. Steam strippers are used in various processes and especially the CDU is a large user. The strip steam temperature may be too high and the strip steam use may be too high. Optimization of these parameters can reduce energy use considerably. This optimization can be part of a process integration (or pinch) analysis for the particular unit.

x Installation of Process Control Systems. A few companies supply control equipment for CDUs. Aspen technology has supplied over 70 control applications for CDUs and 10 optimization systems for CDUs. Typical cost savings are $0.05 - $0.12/bbl of feed, with paybacks less than 6 months. Key Control supplies an expert system advisor for CDUs. It has installed one system at a CDU, which resulted in reduced energy consumption and flaring and increased throughput with a payback of 1 year.

xi Process Integration/Pinch Analysis. Process integration is especially important in the CDU, as it is a large energy consumer processing all incoming crude oil. Older process integration studies show reductions in fuel use between 10 and 19% for the CDU (Clayton, 1986; Sunden, 1988; Lee, 1989) with payback periods less than 2 years. An interesting opportunity is the integration of the CDU and VDU, which can lead to fuel savings from 10-20% (Clayton, 1986; Petrick and Pellegrino, 1999) compared to non-integrated units, at relatively short paybacks. The actual payback period will depend heavily on the layout of the refinery, needed changes in the heat exchanger network and the fuel prices.

xii Installation of Combustion air preheater. By installing a combustion air preheater, using the hot flue gas and an additional FD fan in one of the VDU which used natural draft and had no heat recovery, a refinery in UK by reducing flue gas temperature to 275°C achieved energy cost saving of Rs. 95 lakhs per year with a payback period of 2 years.

xiii Modification in Reduced Crude Cut Point. Typically crude distillation units in India have been designed for reduced crude cut point of 370-380°C. The design also provides necessary features to limit the quantity of diesel range material which goes to the vacuum unit to about 6-8 per cent on reduced crude. This results in additional energy consumption. If the reduced crude oil (RCO)

Parameter Before After Fuel Consumption

(Gcal/H) 66 46

Flue Gas (O )2 3.0 4.5

153152

cut point is reduced and the balance diesel (boiling between the reduced cut point and 370°C) is recovered as the top product in the vacuum column, there is a net saving in energy as can be seen in the following table 4.11.

Table - 4.11 Net Saving of Energy

The total furnace duty is found to reduce as the RCO cut point is brought down, recovery in the atmospheric section. RCO cut point of 350-360°C has been found to be ideally suited resulting in low energy consumption and improved diesel quality.

iv Progressive Distillation Unit

Progressive distillation is the extreme of heat integration between atmospheric and vacuum distillation. It also avoids superheating of light cuts to temperatures higher than strictly necessary for their separation and it avoids degrading the thermal levels associated with the drawing-off of heavy cuts. A progressive distillation unit with integrated CDU/ VDU, saves up to 30% on total energy consumption for these units. The heater process duty (MW/100 tonnes of crude) of a distillation capacity of 10 million tonnes per year is around 17.3 for light crude. Using progressive crude distillation it is reduced to 10.1. The specific energy consumption (overall energy consumption in tones of fuel equivalent per 100 tonnes of crude) for a distillation capacity of 10 million tones per year is 1.7 - 2.0 for light crude, whereas using the progressive distillation unit only consumes 1.15. The energy savings for a 10 million tonnes/year refinery is in the range of 50000 tonnes heavy fuel compared to conventional technology.

xv Use of vacuum pumps and surface condensers

Vacuum pumps and surface condensers have largely replaced barometric condensers in many refineries to eliminate this oily wastewater stream. Replacing the steam ejectors by vacuum pumps will reduce the sour water flow from 10 to 2 m³/h. The vacuum may be generated by a combination of vacuum pumps and ejectors to optimize energy efficiency. Other benefits are cross linked with cross-media effects.

Replacement of the steam ejectors by vacuum pumps will increase the electricity consumption for vacuum generation, but will reduce the heat consumption, the cooling water consumption, the electricity consumed for

S No.

Parameter Case I Case II Case III

1. RCO cut point, °C

370

360

350

2. Crude feed, T/hr

206

206

206

3. RCO, T/hr

93

96

100

4. PA heat recovery-

Atm column

(Million kcal/hr) 11.3

10.4

9.1

5. PA heat recovery- Vac. Column (Million kcal/hr)

8.4 9.1 10.0

6. Furnace duty -Atm, Million kcal/hr

18.2

16.9

15.7

7. Furnace duty -Vac., Million kcal/hr.

4.2

4.8

5.3

8. Total Heat Duty of furnaces, Million kcal/hr

22.4 21.7 21.0

cooling pumps and the consumption of agents used for conditioning of cooling water. Within the refinery there are many processes where surplus steam can be recovered and be used for the production of vacuum. However, an energy management analysis will help to decide, whether use of surplus steam for steam ejection instead of applying vacuum pumps is more efficient than using surplus steam for other purposes.

xvi Reduction of the vacuum pressure in the vacuum distillation unit

Lowering the vacuum pressure, e.g. down to 20-25 mm Hg, will allow a reduction in the furnace outlet temperature, while maintaining the same target cut point of the vacuum residue. This technique would provide some benefits, both in terms of energy conservation and of pollution. The reduction benefits are:-

• A lowered potential for cracking or coking at furnace tubes.• A reduced cracking of feed to lighter products.• A lowered furnace fired duty and hence lowered fuel consumption.

xvii Energy Efficient Design for CDU. Technip and Elf (France) developed an energy efficient design for a crude distillation unit, by redesigning the crude preheater and the distillation column. The crude preheat train was separated in several steps to recover fractions at different temperatures. Thedistillation tower was re-designed to work at low pressure and the outputs were changed to link to the other processes in the refinery and product mix of the refinery. The design resulted in reduced fuel consumption and better heat integration (reducing the net steam production of the CDU). Technip claims up to a 35% reduction in fuel use when compared to a conventional CDU.

xviii Other measures

• Recycling of overhead steam injected into the atmospheric distillation column by using the injector into the VDU - Energy saving 8562 kl/ yr.

• Installation of a side reboiler around the central levels of a distillation column to reduce consumption of heating steam - Energy saving in crude oil equivalent of 483 kl/ yr.

• An increase in temperature of the feed charged from atmospheric distillation unit to the VDU, reduces the specific consumption of energy required for the VDU equivalent of 1314 kl/ yr.

• Utilizing waste heat of heavy gas oil from the atmospheric column results in reduction in steam consumption for the reboiler of stripper - which is crude oil equivalent of 938 kl/ yr.

• The utilization of waste heat of the overhead vapor as a heat source for preheating the water of the boiler reduces steam requirement for heating the deaerator which results in energy reduction in crude oil equivalent of 454 kl/ yr.

155154

Case Study 1 : Trimming of impeller dia of crude boosters from 235 mm pump to

220 mm.

Brief

As the capacity utilization of CDU is 70% this modification called for trimming of pump impeller to reduce the motor power consumption by 15%.

Energy Savings

5Saving of 1.3 x 10 /year KWhr.Investment amount - Rs. 0.5 LakhImprovement effect - Rs. 1.02 Lakhs/yearPay back period - 6 months

Case Study 2 : Installation of online oxygen analyzer

Brief

Installation of online oxygen analyzer on the 2 nos. of AVU furnaces to measure and maintain the percentage of O level level in the range 2-3% so as to maintain 2

furnace efficency beyond 85% maintaining the arch pressure level.

Energy savings

3Saving of 26Nm /hr of fuel gas.

Investment amount - Rs. 2 Lakhs (for 2 nos. of on line O analyser)2

Improvement effect - Rs. 7.64 Lakhs/year (Considering 8000 hrs of operation)Pay back Period - 16 months

Case Study 3 : Reduction of top pressure of Pre flash Drum (PFD) of crude distillation unit

Brief

Reduction of top pressure of PFD (Pre flash Drum) of crude distillation unit from the range 7.5 - 8.5 kg/cm²g to the range 5.5 - 6.5 kg/cm²g for LS crude and reduction of PFD top pressure from the range 10.0 - 12.0 kg/m²g (for various crudes) to the range 8.0-10.0 kg/m²g for HS crude. Fuel saving accrued by reduction the pressure is 1688 SRFT/yr and distillate yield improvement is from 14 to 19%.

Before trimming of impeller

KWhr x 105/year

After trimming of impeller KWhr x 10

5/year

Consumption of Power for the booster pump

9.3 8

Parameter

Before installation of new O2 analyser (the existing

analyzer not working)

After installation of new O2 analyser

Fuel Gas Consumption in 2 nos. of furnaces 877 Nm³/hr 851 Nm³/hr

This has resulted distillate yield improvement from 14% to 19% resulting less energy requirement for vaporization in the column and furnace resulting fuel saving of 1688 SRFT/annum. Hasys software was used to arrive at the energy saving effects operating pressure for various crudes.

Energy Savings

Saving of 1688 SRFT/year

Investment amount - NilImprovement Effect - Rs. 2.4 crores/yearPay back Period - Immediate

Case Study 4: Energy Efficiency improvement through crude preheat train optimization in the refinery

Brief

The preheat temperature of crude before entering into the furnace of crude distillation unit (for the processing of LS crude) is on an average 225°C. Pinch technology was applied to optimize, reorient the preheat exchangers. This modification calls for installation of new exchangers (8 nos.) and new 13 nos. of pumps and rec-orientation of exchangers. The modification also calls for replacement of existing main fractionator for reflux drum and provision of boot in the stabilizer.

By carrying out the above modification crude preheat temperature increased from 225°C to 284°C min. thereby reducing the fuel consumption in the furnace by an amount 6874 kL/year. The investment for the total modification is 34.6 crores.

Energy Savings

Annual Fuel Oil Saving - 6874 kL of FO/year Investment amount - Rs. 34.6 croresImprovement Effect - Rs. 11.6 crores/yearPay back Period - 3 years

4.5.3 Production of Lube Oil Base Stock

i Vaccum Distillation

The atmospheric residuum or reduced crude leaving the bottom of the CDU column passes through the fired heater into the flash zone of the VDU where it is fractionated into lube distillates. Steam is introduced into the VDU flash zone to lower the vapor pressure of the distillates and permit removal of high boiling hydrocarbons.

Refiners have in recent years refurbished existing VDUs and installed new VDUs with high efficiency internals to reduce the flash zone pressure and improve the purity and yield of lube oil distillates obtained from lube crudes. These changes result in improved processing response in down stream units and improve base oil viscosity.

157156

Case Study 5 : Reduction of injection steam in vacuum column by recycling overhead steam.

Brief

Steam is injected into the vacuum distillation column to reduce the partial pressure of lighter fractions. The injected steam goes to the overhead condenser as overhead steam to be condensed to waste water. This modification recycled the injected steam back to the distillation column by means of an injector, thereby achieving energy saving.

The steam ejector generates vacuum inside the body by injecting high pressure (driving steam) at a high velocity from nozzles and induces the low pressure steam (supply steam) which is used as recycled steam in this case. This enables the hitherto unused and discharged low pressure steam to be pressurized and reused.

Energy Savings

Reduction of 15 Tonnes/hr. of Steam

Investment amount - 6 croresImprovement effect - 8 crores/yearPay back Period - 9 months

ii Deasphalting Process

Deasphalting is an extractive - precipitation process. The purpose of the process is the removal of asphaltenes, resins and metals from vacuum residua and very heavy vacuum gas oils.

The deasphalted oils from atmospheric residua and very heavy vacuum distillates are used as feedstocks to lube processing units for the manufacture of lube base oils ranging from solvent neutral oils to cylinder oils and bright stocks.

iii Solvent Recovery Techniques in propane Deasphalting unit

Conventional Solvent Recovery Supercritical Solvent RecoverySingle effect evaporation ROSE@ processDouble effect evaporationTriple effect evaporation DEMEX process

Double and triple effect evaporation units use 40 to 50 percent of the energy of a single effect evaporation for solvent recovery. These reductions in energy are obtained because the heat required to vaporize the solvent in the higher pressure flash vaporization stages is used to vaporize solvent in the next lower pressure flash vaporization stages. The amount of energy saved is proportional to the solvent to feed ratio and the cost of steam, fuel and electrical power.

After

improvement

Steam consumption (for 5 MMT/year t’put)

Reduction of 120,000 t/year (15 tons/hr)

Operating hours : 8000 hr/year

iv Solvent Extraction of Lube Distillate

EXON & Texaco Development Corporation Refining Processes based on the use of N-methyl-2-pyrrolidone (NMP) as the extraction solvent are being used in the refineries as NMP Process.

This process is being used as a replacement for furfural and phenol in the extraction of lube base stocks.

The by products from lube solvent refining processes are aromatic extracts which are used in manufacture of asphalt, carbon black, fuel, petrochemicals, rubber and as coker and FCCU feed.

Solvent extraction is used for the purpose of removing aromatics and other undesirable constituents to improve the VI and quality of lube base stocks.

v Energy Reduction Techniques for extraction of lube distillate

a Multiple effect evaporation

The solvent based processes used for the manufacture of lube oils are energy intensive because large volumes of solvent must be recovered by flash distillation for recycle in the process. The number of stages used for evaporation of the solvent has a significant effect on the energy cost.

b Single effect

1. Solvent is vaporized at one pressure level2. Energy is wasted in condensation; it is not recovered

c Double effect

1. Solvent is vaporized at two pressure levels.2. One half of he solvent is vaporized at each pressure level3. Condensing vapors are used to operate the first evaporator4. Energy requirements are reduced by 45 to 50 percent

d Triple effect

1. Solvent is vaporized at three pressure levels2. One third of the solvent is removed at each pressure level3. Condensing vapors are used to operate the first two stages4. Energy requirements are reduced by an additional 30 - 33 percent

compared to double effect evaporation5. Energy requirements are 30 to 33 percent of single effect.

vi Solvent Dewaxing Process

The raw paraffin distillates and residual oils leaving the crude stills contain wax and are normally solids at ambient temperature. The desphalting and refining processes concentrate the wax in the base oil feedstocks. Removal of wax from these fractions is necessary to permit manufacture of lubricating oils with the desired low temperature properties. Although the cold settling pressure filtration processes and centrifuge dewaxing processes have for the most part been replaced by solvent dewaxing using MEK (Methyl Ethyl Ketone)/Toluene and MIBK/ Toluene. The

159158

wax produced in this process is separated by filtration and is a by product of this process called as Slack Wax. The solvent recovery units in this process consumes considerable amount of energy.

a Inert Gas Stripping

This involves using inert gas in place of steam for stripping the last traces of solvent from the dewaxed oil and wax.

b Benefits from use of Inert Gas Stripping

Energy requirements reduced Dilution ratios reducedDewaxed oil yield increased Solvent losses reducedDewaxing differential decreased Maintenance costs reduced

vii Catalytic Dewaxing/isodewaxing Process

Modern wax processing routes for producing VHVI LOBs is wax or paraffin waxy isomerisation straight away from the lube stocks by using catalyst to reduce pour point.

Case Study 6 : Use of controlled hot refrigerant gas by-passing SDU PlantChiller

Brief

Use of controlled hot refrigerant gas by-passing SDU Plant Chiller to maintain desired suction pressure and stop use of steam tracing on brine return line.

For stable operation, the suction pressure should be maintained at a desired minimum level even in the absence of real heat load. This can be achieved by controlled discharge hot gas bypass arrangement with the control valve operating based on feed back of suction pressure. The control valve can be programmed to control the suction pressure in a tight bond. This can avoid the use of steam to create spurious heat load and save about 1.2 TPH steam.

Energy Savings

Steam saving potential is 1.2 TPH and 9600 T/year (considering 8000 hrs of operation)Investment amount - Rs. 10 Lakhs

(for the modification i.e control valve, piping & instrumentation) Improvement effect - Rs. 30 Lakhs/year Pay back Period - 4 months

4.5.4 Hydrogen Management and Recovery

Hydrogen is used in the refinery in processes such as hydrocrackers and desulfurization using hydrotreaters. The production of hydrogen is an energy intensive process using naphtha reformers and natural gas-fueled reformers. These processes and other processes also generate gas streams that may contain a certain amount of hydrogen not used in the processes or generated as by-product of distillation of conversion processes. In addition, different processes have varying quality demands for the hydrogen feed. Reducing the need for hydrogen make-up will reduce energy use in the reformer and reduce the need for natural gas.

The major technology developments in hydrogen management within the refinery are hydrogen process integration or hydrogen cascading and hydrogen recovery technology (Zagoria and Huycke, 2003). Revamping and retrofitting of existing hydrogen networks can also increase hydrogen capacity between 3% and 30% (Ratan and Vales, 2002).

i Hydrogen Integration

Hydrogen network integration and optimization at refineries is an important application of pinch analysis. Most hydrogen systems in refineries feature limited integration and pure hydrogen flows are sent from the reformers to the different processes in the refinery. But as the use of hydrogen is increasing in refineries, the value of hydrogen is more and more appreciated. Using the approach of composition curves used in pinch analysis, the production and uses of hydrogen of a refinery can be made visible.

ii Hydrogen Recovery

a Utilizing low purity hydrogen streams

Hydrogen recovery is an important technology development area to improve the efficiency of hydrogen recovery, reduce the costs of hydrogen recovered and increasing the purity of the resulting hydrogen flow. Hydrogen can be recovered indirectly by routing low-purity hydrogen streams to the hydrogen plant (Zagoria and Huycke, 2003). Hydrogen can also be recovered from offgases by routing it to the existing purifier of the hydrogen plant or by installing additional purifiers to treat the offgases and ventgases. Suitable gas streams for hydrogen recovery are the offgases from the hydrocracker, hydrotreater, coker, or FCC. The cost savings of recovered hydrogen is around 50% of the costs of hydrogen production (Zagoria and Huycke, 2003).

b Using Absorption/ Membrane Technology

Hydrogen can also be recovered using various technologies, of which the most common are pressure swing and thermal swing absorption, cryogenic distillation, and membranes. The choice of separation technology is driven by desired purity, degree of recovery, pressure, and temperature. Various manufacturers supply different types of hydrogen recovery technologies, including Air Products, Air Liquide, and UOP.Membrane technology generally represents the lowest cost option for low product rates, but not necessarily for high flow rates (Zagoria and Hucyke, 2003).

c Using PSA Technology for High flow rates

For high-flow rates, PSA technology is often the conventional technology of choice. PSA is the common technology to separate hydrogen from the reformer product gas. Hundreds of PSA units are used around the world to recover hydrogen from various gas streams. Cryogenic units are favored if other gases, such as LPG, can be recovered from the gas stream as well. Cryogenic units produce a medium purity hydrogen gas stream (up to 96%). Membranes are an attractive technology for hydrogen recovery in the refinery. If the content of recoverable products is higher than 2-5% (or preferably 10%), recovery may make economic sense (Baker et al., 2000).

161160

iii Hydrogen Production

If there is excess steam available at a plant, a pre- reformer can be installed at the reformer. Adiabatic steam reforming uses a highly active nickel catalyst to reform a hydrocarbon feed, using waste heat (900°F) from the convection section of the reformer. This may result in a production increase of as much as 10% (Abrardo and Khurana, 1995). The technology can also be used to increase the production capacity at no additional energy cost, or to increase the feed flexibility of the reformer. This is especially attractive if a refinery faces increased hydrogen demand to achieve increased desulfurization needs or switches to heavier crudes. Various suppliers provide pre-reformers including Haldor-Topsoe, Süd-Chemie, and Technip-KTI.

iv Other Options

• By reducing steam/ carbon ratio in the hydrogen production unit energy saving in crude oil equivalent of 3848 kl/ yr is achieved.

• The minimization of surplus hydrogen production and reduction in energy consumption of flare required to combust the gas in a hydrogen production unit results in energy saving which is crude oil equivalent of 1431 kl/yr.

• Installation of a membrane separator for hydrogen results in energy saving and reduction of cost by recovering hydrogen from refinery by-product gas - Energy saving in crude oil equivalent of 6466 kl/yr.

Case Study 7 : De-staging of 6 stages to 5 stages of HGU reformer boiler fuelpump

Brief

De-staging of 6 stages to 5 stages of HGU reformer boiler fuel pump so as to elimate pressure difference between the pump discharge pressure, 44 kg/cm²g and boiler drum pressure 30kg/cm²g. This pressure drop is presently maintained by reduction of pressure through a control valve.

By de-staging of the pump from 6 stages to 5 stages, the discharge pressure of the pump will come down from 44 kg/cm²g to 35 kg/cm²g eliminating/reducing the pressure drop in the boiler drum feed control valve. Power consumption of the pump motor will come down from 50.7 kW to 43 kW resulting saving of 58,000 kwh/year.

Energy Savings

Before de -staging of HGU boiler feed pump

After de-staging of HGU boiler feed pump

Power Consumption

50.7 kW 43 kW

Saving of 7.7 kW of power resulting 58,800 kWh/year of power saving.

Investment amount - Rs. 45,000/- (for de-staging)Improvement effect - Rs. 41,000/-/year Pay back Period - 1.1 year

Case Study 8 : Reduction of steam / carbon ratio

Brief

The steam to carbon ratio of this hydrogen production unit was 5.5 and higher than other refineries values of 4.5 to 5.0 because of the specific energy consumption is high, the refinery embarked on a modification to reduce the steam to carbon ratio and successfully reduced it to 4.7

Problems that are anticipated when the steam to carbon ratio is reduced are as follows;

• Increase carbon deposits on the catalysts• Rise of surface temperature of the reaction tubes of the reforming furnace• Insufficient steam supply to the conversion reactors• Insufficient heat supply to the absorption agent regenerating column• Foaming in the absorption tower

At steam to carbon ratio - 4.7 or higher none of the problems except foaming was encountered.

Countermeasures to foaming:

• The cause of foaming was identified, blow velocity of the absorbent became too fast because the ceramic packing in the absorption tower had been broken into small pieces.

• Replacement of the ceramic packing by more study stainless steel packing. Solved the foaming problem. As a result the steam to carbon ratio was reduced from 5.5 to 4.7

Energy Savings

Investment amount - Operational improvement without capital investmentImprovement effect - 6 crores per annum

Before modification After modification

Fuel consumption – Fuel Oil Equivalent 3,630 kl/y reduction

Fuel Consumption – Crude Oil Equivalent 3,848 kl/y reduction

163162

Case Study 9: Use of H rich gas catalytic reformer unit (via HGU) for2

recycling in CRU in place of use of pure H2 ex HGU and PSA.

Brief

The H is generated from HGU and PSA using feed as Natural Gas. A part of pure H 2 2

is being recycled to CRU. At the same time, H rich gas generated in the catalytic 2

Reforming Unit (CRU) is routed to Fuel Gas. This Hydrogen rich gas ex CRU can be routed to HGU replacing NG feed and this H after HGU can be recycled back to 2

CRU stopping recycling of pure H from HGU and PSA. This can save use of NG 2

from outside source to HGU and PSA for the production of H and the net saving of 2

natural gas is to the tune of 38 kg/hr.

Higher chlorine content in the hydrogen rich gas is harmful to the reformer catalyst. The chlorine content of H rich gas is 3 ppm. When an amount of 38 kg/hr of H rich 2 2

gas is mixed with 1229 kg/hr of natural gas feed going to HGU, the concentration of chlorine comes down to 0.09 ppm which is not at all harmful to CRU catalyst. (as it is less than 1 ppm. However, installation of chlorine guard at the downstream of HGU can also take care of chlorine shock to CRU catalyst.

Energy Savings

NG Saving = 38 kg/hr

Investment amount - Rs. 6 lakhs (For lying pipeline from CRU to PSA outlet line)Improvement effect - Rs. 18 lakhs/yearPay back Period - 4 months

Case Study 10 : Installation of a membrane separator for hydrogen

Brief

The hydrogen production cost of the existing hydrogen production plant is high. Installation of a membrane separator for hydrogen realized energy saving and reduction of cost by recovering hydrogen from refinery byproduct gas streams and consequently by reducing the operation rate of the existing hydrogen production plant

Energy Savings

Investment amount : Rs 120 millionImprovement effect : Rs 52 million /yearInvestment payback : 2.5 years

Attribute Effect by introduction

Fuel oil equivalent of fuel consumption

Reduction of 6,100 kl/y

Crude oil equivalent of fuel

consumption Reduction of 6,466 kl/y

Case Study 11 : Computer-controlled reduction of surplus hydrogen inHydrogen production unit

Brief

The operation of the hydrogen production unit is required to ensure stable supply of hydrogen to the related units regardless of fluctuation of all operational variations. Because of this requirement, production quantity of purified hydrogen tends to be excessive, resulting in production loss. This method minimizes the surplus hydrogen production by computer control.

Conventionally, the quantity of hydrogen production was manually controlled in response to the changes in demand for hydrogen as well as the changes in the amount of raw materials fed into the hydrogen production unit. However, the control was insufficient because of the manual operation, and the surplus hydrogen tends to be about 2.5% on an average. The surplus hydrogen had to be flared. After modification, production quantity of hydrogen was controlled by ACS computers in response to changes in hydrogen demand and in the amount of raw materials and production loss of the hydrogen production unit became 0 %.

Energy Savings

Investment amount : Rs 4 million,Improvement effect : Rs 12 million/yearInvestment payback : 0.4 year

Case Study 12 : Routing of excess low pressure separator off gas exHydrocracker to hydrogen generation plant

Brief

Hydrocracker unit low pressure separator off gas which is in excess has been used as recycle H2 for HGU. This has resulted in the reduction of make up H2 production demand.

Energy Saving Effects

Fuel oil saving to the tune of 1740 MT per annum

Investment amount : NilImprovement effect : Rs. 1.74 croresPay back Period : Immediate

4.5.5 Fluid Catalytic Cracker (FCC) Fluid catalytic crackers are net energy users, due to the energy needed to preheat the feed stream in a modern refinery, FCC energy use is estimated at 6% of total energy use.

Attribute After improvement Fuel consumption - heavy oil equivalent

1,350 kL/y reduction

Fuel consumption - Crude oil

equivalent 1,431 kL/y reduction

165164

The following table 4.12 shows the energy and process materials usage in the catcrackers:-

Table 4.12

Virtually all the heat required in a FCC unit is generated in the regenerator. The catalyst used depends greatly on the type of product required and can be silica-alumina substrate carrying rare earth and/ or precious metals or can be based on zeolites.

The fuel oil from the CDU is converted into lighter products over a hot catalyst bed in the fluid catalytic cracker (FCC). FCC is the most widely used conversion process in refineries. The FCC produces high octane gasoline, diesel, and fuel oil. The FCC is mostly used to convert heavy fuel oils into gasoline and lighter products. The FCC has virtually replaced all thermal crackers.

Energy Conservation Options in FCC

i Installation of Process Control System

Several companies offer FCC control systems, including ABB Simcon, AspenTech, Honeywell, Invensys, and Yokogawa. Cost savings may vary between $0.02 to $0.40/bbl of feed with paybacks between 6 and 18 months. Timmons et al. (2000) report on the advantages of combining an online optimizer with an existing control system to optimize the operation of a FCC unit at the CITGO refinery in Corpus Christi, Texas. The Citgo refinery installed a modern control system and an online optimizer on a 65,000 bpd FCC unit. The combination of the two systems was effective in improving the economic operation of the FCC. The installation of the optimizer led to additional cost savings of approximately $0.05/barrel of feed to the FCC, which resulted in an attractive payback (Timmons et al., 2000).

ii Opportunities for Power Recovery

FCC runs at elevated pressures, enabling the opportunity for power recovery from the pressure in the flue gas. The major application for power recovery in the petroleum refinery is the fluid catalytic cracker (FCC). However, power recovery can also be applied to hydrocrackers or other equipment operated at elevated pressures. Modern FCC designs use a power recovery turbine or turbo expander to recover energy from the pressure. The recovered energy can be used to drive the FCC compressor or to generate power. Power recovery applications for FCC are characterized by high volumes of high temperature gases at relatively low pressures, while operating continuously over long periods of time between

FCC RCC

Fuel (MJ/t) 120 – 2000 120 – 1200

Electric ity (kWh/t) 8 – 50 2 – 60

Steam consumed (kg/t 30 – 90 50 – 300

Steam produced (kg/t) 40 – 60 100 – 170

Cooling water (m3/t,

DT-17ºC)

5 – 20 10 – 20

Catalyst make -up (kg/t) 0.4 – 2.5 2 - 4

maintenance stops (> 32,000 hours). There is wide and long-term experience with power recovery turbines for FCC applications. Various designs are marketed, and newer designs tend to be more efficient in power recovery. Recovery turbines are supplied by a small number of global suppliers, including GE Power Systems.

A refinery in Houston, USA replaced an older power recovery turbine to enable increased blower capacity to allow an expansion of the FCC. The re-rating of the FCC power recovery train led to power savings of 22 MW. Petro Canada's Edmonton refinery replaced an older turbo expander by a new more efficient unit, saving around 18 TBtu annually.

Power recovery turbines can also be applied at hydrocrackers. Power can be recovered from the pressure difference between the reactor and fractionation stages of the process. In 1993, the Total refinery in Vlissingen, the Netherlands, installed a 910 kW power recovery turbine to replace the throttle at its hydrocracker (get data on hydrocracker). The cracker operates at 160 bar. The power recovery turbine produces about 7.3 million kWh/year (assuming 8000 hours/year). The investment was equal to $1.2 million (1993$). This resulted in a payback period of approximately 2.5 years at the conditions in the Netherlands (Caddet, 2003).

Iii Optimisation of Process Design

The product quality demands and feeds of FCCs may change over time. The process design should remain optimized for this change. Increasing or changing the number of pumparounds can improve energy efficiency of the FCC, as it allows increased heat recovery (Golden and Fulton, 2000). A change in pumparounds may affect the potential combinations of heat sinks and sources.

iv Heat Recovery from the regenerator flue gas

Heat recovery from the regenerator flue gas is conducted in a waste heat boiler or in a CO-boiler. The steam produced in the CO boiler normally balances the steam consumed. Installing an expander in the flue gas stream from the regenerator can further increase the energy efficiency. The waste heat boiler recovers the heat from the flue gas and the expander can recover part of the pressure to be used in the compression of the air needed in the regenerator. An example of the application of an expander saved 15MWe for the flue gas generated by a FCC of a capacity of 5Mt/yr.

v Waste Water Management within FCCU

The latest design of catcrackers contained a cascading overhead wishing section which minimizes water usage. Re-use waste water generated in FCCU can be used for the desalters thereby reducing water usage and reuse of water refinery.

New design and operational tools enable the optimization of FCC operating conditions to enhance product yields. Petrick and Pellegrino (1999) cite studies that have shown that optimization of the FCC-unit with appropriate modifications of equipment and operating conditions can increase the yield of high octane gasoline and alkylate from 3% to 7% per barrel of crude oil. This would result in energy savings.

167166

vi Other Options

• Optimization of heat recovery from the overhead, middle and bottom refluxes improves the energy saving effects in FCCU - energy reduction in crude oil equivalent of 1884 kl/ yr.

• In the FCC unit, the reduction of pressure inside the regeneration column reduces the consumption of steam for driving the air blower for the regeneration column resulting in energy saving of 1024 kl/ yr of oil equivalent.

Case Study 13 : Energy saving by reducing the pressure inside the regeneration column.

Brief

The pressure within the fluid catalytic cracking (FCC) unit can be reduced by increasing the capacity of the cooler at the top of the FCC distillation column. The modification achieves energy saving by reducing the pressure inside the regeneration column and thereby reducing, the consumption of steam for driving the air blower for the regeneration column.

The possibility of the following items were examined before modification.

(1) To reduce the pressure inside the system by increasing the capacity of the air cooler at the top of the distillation column.

(2) To reduce the air volume of the air blower for the regeneration column.

Air volume of the air blower and air pressure of the regeneration column before and after improvement.

Energy Savings

Investment amount - Rs. 14.5 lakhs (For modification of air cooler)Improvement effect - Rs. 4.9 lakhs Pay back Period - 3 years

Case Study 14 : Power recovery system in Fluid catalytic cracking (FCC) unit

Brief

The flue gas, or coke combustion gas (containing CO at a high content), generated from the regenerator of a fluid catalytic cracking (FCC) unit of petroleum refining process, is normally sent to a CO boiler after pressure reduction using a pressure-

Before improvement

After improvement

Effect

Regeneration column air pressure (kg/cm2) 2.86 2.63 0.23 reduction

Air blower. Air volume (Nm3/hr) 1755 860 895 reduction

After improvement FCC oil throughout 8,42,000 Kl/y

increase High Pressure Steam Consumption 12,557 t/y reduction Crude oil equivalent 1,024 kl/y reduction

reducing valve and pressure-reducing orifice. The present technology recovers a portion of the pressure energy of this gas in the form of power by installing an expander turbine for pressure reduction. The flue gas, after being de-pressured by the expander turbine, is sent to the CO boiler for combus- tion.

The coke (CO gas) required for 10,000 BPD production is 3 to 6 tons. 11 to 14 kilograms of air is required for combustion of one kilogram of coke. The power required for feeding this combustion air accounts for more than 50 percent of the entire power requirement of the FCC unit.

After modification

1) The gas expander turbine is connected with the air blower and a steam turbine on the same axis.

2) The coke combustion gas discharged from the regenerator has a pressure from 21.5 to 3.0 Kg/cm g and temperature from 620 to 730ºC. This flue gas is sent to a

CO boiler where its CO content is burned to recover heat energy in the form of steam.

Energy Savings

Investment amount : Rs 800 million Improvement effect : Rs 336 million/year InvestmentPay back Period : 2.5 years

4.5.6 Catalytic Reforming

Reforming is undertaken by passing the hot feed stream through a catalytic reactor. In the reactor, various reactions such as isomerization, dehydrogenation and hydrocracking occur to reformulate the hydrocarbons in the stream. Some of these reactions are endothermic and others are exothermic. The types of reactions depend on the temperature, pressure and velocity in the reactor. Undesirable side reactions may also occur and need to be limited.

Two techniques, namely Continuous regeneration and Semi-regeneration are employed in catalytic reforming. In the regeneration process of the catalyst in a continuous reforming unit, a slip stream of catalyst is withdrawn, 60-80 kg coke/ tonne feed is burned off with hot air/ steam. In the cyclic or semi-regenerative units, the regeneration of catalyst and the resulting emissions are discontinuous.

While the continuous catalyst reformer process has higher energy efficiency due to the heat recovery from product, from pump around and due to integration with topping and vacuum units, the heat integration is lower in the semi-regenerative

Before

installation After

installation

Generation capacity

(35,000 BPD) - 7,000 kW

Annual generation capacity (8,000 hour/year)

- 56,000 MWh

Crude oil equivalent - Reduction of 13,600 kl/year

169168

reformer process. However, many semi-regenerative units have applied better feed affluent exchange to minimize energy consumption.

Table 4.13 given below shows the summary of the utilities and catalyst requirement for the catalytic reforming.

Table - 4.13

i Increased Product Recovery

Product recovery from a reformer may be limited by the temperature of the distillation to separate the various products. An analysis of a reformer at the Colorado Refinery in Commerce City, showed increased LPG losses at increased summer temperatures. The LPG would either be flared or used as fuel gas. By installing a waste heat driven ammonia absorption refrigeration plant, the recovery temperature was lowered, debottlenecking the compressors and the unsaturated light-cycle oil streams (Petrick and Pellegrino, 1999). The heat pump uses a 150°F waste heat stream of the reformer to drive the compressor. The project resulted in annual savings of 65,000 barrels of LPG. The recovery rate varies with ambient temperature. The liquid product fraction contained a higher percentage of heavier carbon chain (C5, C6+) products. The payback period is estimated at 1.5 years.

ii Reduction of system pressure (Separator drum Pressure)

Modern CCR (Continuous Catalyst regeneration) process can maintain a very low pressure of about 3.5 kg/m2g. This low pressure obviously calls for high severity of operation and faster deposition of coke on catalyst. But the continuous regeneration can remove the coke from the catalyst. As a whole this can reduce the power consumption of recycle compressor and fetch energy saving as a whole.

iii Other Options

Recycle ratio (H recycle flow/feed) plays an important role in CRU for 2

maintaining the catalyst health with respect to catalyst coking. The reduction of this ratio increases the coking tendency of the catalyst and decreases the cycle length (between two successive regeneration of catalyst in semi regeneration process). However optimization of the same can give reduction of power for driving the recycle compressor.

Parameter Reforming Semi-regenerative process

Continuous regeneration process

Electric power, kWh

Specific consumption (kWh/t)

-

25-50

246*

55

6142*

-

Fuel fired, GJ

Specific fuel consumption (MJ/t) -

1400 -

2900

185*

71.5 t/kt 232*

Cooling water, 3(m /t, D0T=10 C)

1 - 3 0.12 – 3 5.5

High-pressure steam generated, kg/t

50-90

64 - 90

97

Boiler feed water, kg/t

170

22

* Values related to a capacity of 2351 t/d. Specific values related to capacity values.Note: First column gives ranges for all types of reformers.

Reduction in recycled gas quantity to the allowable limits in the catalytic reforming unit saves the power for recycling the gas and the heat power required for the furnace resulting in energy saving.

Case Study 15 : Reduction of quantity of the recycle gas in the reforming unit

Brief

In the reforming unit a gas rich in hydrogen is circulated for maintaining the hydrogen concentration necessary for the reaction and for preventing deterioration of the catalyst due to carbon deposition on the catalyst. The volume of the recycling gas often becomes more than necessary.

By reducing the volume of recycled gas, it is possible to reduce the power for driving the compressor as well as heat required for the furnace. However, as the decrease of the recycling gas may lead to the deterioration of the catalyst, the reduction of the recycle gas to be controlled within the allowable limit.

Energy Savings

Saving of Fuel - 2.5 Kl/daySaving of Electricity - 5120 KWhr./dayInvestment amount - Operational improvement without capital investmentImprovement Effect - Rs.1.33 crores/annum

(Basis: 330 days of operation per annum)

Case Study 16 : Installation of 4 nos. of on line O2 analyzer in the four furnacesof CRU to maintain the O2 level

Brief

By installing on line O analyser will allow the measurement and control of % O in 2 2

the flue gas. By controlling % of O level at 2-3% will increase the furnace efficiency 2

to 80% from the existing level of about 77%. This will ensure saving of 30 Nm3/hr of fuel gas saving.

Energy Savings

Before

After

Effect

Molar ratio of hydrogen/hydrocarbon

6.4 5.1

Fuel 2.56 kl/d reductionEnergy Consumption Electricity 5,120 kWh/d

reduction

Before installation on line O2

analyser in the 4 nos. of furnaces in CRU

After installation of online O2 analyser in the 4 nos. of furnaces in CRU

Fuel Gas Consumption

1000 Nm3/hr

970 Nm

3/hr

171170

3Saving of 30 Nm /hr of fuel gas.

Investment amount - Rs. 20 Lakhs (for 4 nos. of O analyser)2

Improvement effect - Rs. 12.6 Lakhs/year Pay back Period - 22 months

4.5.7 Coking

A new generation of coking processes has added additional flexibility to the refinery by converting the heavy bottom fed into lighter feedstocks and coke. Coking can be considered a severe thermal cracking process. Modern coking processes can also be used to prepare feed for the hydrocracker.

Coking processes :

Two types of Coking processes are used in Petroleum refineries, the delayed and fluid coking processes that produce coke and the flexi coking process which gasifies the coke produced in a fluid coking process to produce coke gas.

i The Delayed and fluid coking

The basic process is the same as thermal cracking except that feed streams are allowed to react for longer without being cooled. The delayed coking feedstream of residual oil is first introduced to fractioning tower where residual lighter materials are drawn off and the heavy ends are condensed. The heavy ends are removed, heated in a furnace and then fed to a insulated vessel called the coke drum where the cracking takes place. In the case of fluid coking, the fluidized bed is used. Temperature (440 - 450 °C), pressure (1.5 - 7.0 bar g) and recycle ratio are the main process variables which contribute to the quality and yields of delayed coking products. Energy & process materials required in the Delayed coking Process are given in the Table 4.14 :

Table - 4.14

ii Flexi coking

In the Flexi coking process, a heavy feed is preheated to 315-370 °C and sprayed on a bed of hot fluidized coke (recycled internally). The coke bed has a reaction temperature between 510-540 °C. At this temperature, cracking reactions take place. Cracked vapor products are separated in cyclones and are quenched. Some of the products are condensed, while the vapors are led to a fractionator column, which separates various product streams. The coke is stripped from other products, and then processed in a second fluidized and reactor where it is heated to 590 °C. The hot coke is then gasified in a third reactor in the presence of steam and air to produce synthesis gas. Sulfur (in the form of H S) is removed, and the synthesis gas 2

(mainly consisting of CO, H , CO and N ) can be used as fuel in (adapted) boilers or 2 2 2

furnaces. The coking unit is a consumer of fuel (in preheating), steam and power. Utility requirement in the Flexi Coking Process is given in Table 15: -

Fuel (MJ/t)

Electricity (kWh/t) Steam consumed

(kg/t) Steam produced

(kg/t) Cooling water (m3/t, DT = 17 °C)

800 – 1200 20 – 30 50 – 60 50 – 125 6 – 10

Note: Electricity including the electric motor drives for the hydraulic decoking pump.

Table - 15

Coking Process - Energy Conservation Measures

i Heat Integration: The delayed coking process has a low level of heat integration. The heat to maintain the coke drums at coking temperature is supplied by heating feed and the recycle stream in a furnace. The atmospheric or vacuum residue can be fed straight into the delayed coking unit without intermediate cooling, which results in high heat integration level between the different units and saves considerable amount of cost on heat exchangers.

ii Combustion of Coking Gas: - The Flexi Coking process has a high level of heat integration. The only source of heat in the Flexi Coking Process is the gasifier, where coke is partially oxidized. The remainder of the heat in the coker gas is recovered by generating steam. The energy efficiency can be further increased of the coking gas is combusted in a gas turbine of a combined cycle unit.

iii Use of Oily Sludges as Coker feed stocker: - In the case of delayed coker, the sludge can be injected into the coking drum with the quench water or can be injected into the coker blowdown contactor used in separating the quenching products. In refineries with a coker, oily sludges from the waste water treatment plant can be used to produce coke which can be further used as fuel within the refinery.

iv Water use in the cooling/ cutting processes: The water used in the cutting/ cooling operations is continuously re-circulated with a bleed-off to the refinery wastewater treatment. Settling and filtering over a vacuum filter enables the reuse of this water resulting in a "Closed Water Loop" for water make up to the quenching and cutting water loop.

Case Study 17: Installation of VFD for ID & FD fans of DCU furnace.

Brief

This modification installs VFD for 1 No. each of ID and FD fan of 60 kW each.

Energy Savings

Reduction of 1.60 lacs KWhr./year

Investment amount - 15 lacsImprovement effect - 5.6 lacs / yr (for 8000 hrs & electricity cost @

Rs. 3.5 per kWhPay back Period - 32 months

Before installation of VFD

After installation of VFD

Consumption of Power in ID/FD

60 kW 50 kW

Electricity (kWh/t)

Steam consumed (kg/t)

Steam produced (kg/t)

Cooling water (m3/t, DT=10 0C)

60 – 140 300 – 500 (MP) 500 – 600 (HP) 20 - 40

173172

Case Study 18 : Proper insulation of DCU furnace.

Brief

Furnace surface temperature varied between 60 - 96°C proper insulation called for the safety and energy conservation point of view.

Energy Savings

Saving of 110 kl of FO

Investment amount - 32 lacsImprovement effect - 18 lacs Pay back Period - 1.8 years

Case Study 19 : Installation of the lowest sized impeller in the DCU

Brief

Installation of the lowest sized impeller as suggested by manufacture in the DCU (Delayed coking unit) fractionators bottom pump to reduce the operating point

2 2from 57 kg/cm g to 40 kg/ cm g to elimate the pressure drop in the feed control valve to Coker furnace.

1. In operation of DCU fractionator bottom pump which sends the material to furnace through a control valve where the pressure developed by the pump

2gets lost by 20 to 30 kg/cm (50% of the pressure developed by the fractionators bottom pump is lost).

2. By replacing the existing impeller of the pump by the smallest impeller (as per manufacturer) the discharge pressure of the pump can be brought down to 40kg/cm2g thereby eliminating the pressure drop in the control valve.

Energy Savings

Reduction of power 6.0 lakh kWh/year.

Investment amount - Rs. 1 Lakh (for 2 nos. of pump motor)Improvement effect - Rs. 4.2 Lakhs/year Pay back Period - 3 months

Case Study 20 : Heat recovery from RFO stream in DCU (Delayed Coking Unit).

Brief

The RFO was getting cooled by on open box cooler. Two new exchangers were installed. One exchangers is thermosyphon type where the RFO is routed first to

o obring down the temperature from 400 C to 200 C and to generate steam at low 0pressure. This stream of 200 C RFO then routed to normal shell and tube exchanger

to heat BFW water. The additional steam generated was sent to furnace. This was resulted in FO saving of about 1860 MT/year. New lines were laid for interconnecting RFO stream to thermos phone exchanger.

Before replacement of impeller of the fractionators bottom pump

After replacement of impeller of the fractionators bottom pump

Consumption of power by fractionators bottom pump motor

215.5 kW 143.5 kW

Energy Savings

Fuel Saving - 1800 mt/year in DCU furnaceInvestment amount - Rs. 1.06 crores (For installation of 2 nos. of exchangers and allied piping)Improvement effect - 1.70 crores/yearPay back Period - 8 months

4.5.8 Hydrotreater

Desulfurization is becoming more and more important as probable future regulations will demand a lower sulfur content of fuels. Desulfurization is currently mainly done by hydrotreaters. In a hydrotreater, the feedstream is mixed with hydrogen and heated to a temperature between 260-430ºC. In some designs, the feedstream is heated and then mixed with the hydrogen. The reaction temperature should not exceed 430ºC to minimize cracking. The gas mixture is led over a catalyst bed of metal oxides most often cobalt or molybdenum oxides on different metal carriers. The catalysts help the hydrogen to react with sulfur and nitrogen to form hydrogen sulfides H S and ammonia. The reactor effluent is then cooled, and 2

the oil feed and gas mixture is then separated in a stripper column. Part of the stripped gas may be recycled to the reactor.

The operating conditions are dependent on feedstock composition (related to crude source as well as type and severity of prior processing), catalyst and product specifications.

The feedstocks to hydrogen finishing processes include the following;

Solvent extracted deasphalted oils Hydrocracked distillatesHydrocracked deasphalted oils Deasphalted oilsSolvent refined distillates Slack waxesUnrefined distillates Hard waxes

The effects of hydrogen finishing temperature and pressure are highly dependent on the quality of the feedstock, produce specifications and the type of catalyst used. An increase in temperature or pressure will normally improve neutralization, desulfurization, denitrification, product colour and product stability. However, increasing the temperature above some maximum which is related to the catalyst and feedstock quality will degrade the colour, colour stability, oxidation stability and other properties of the base oil and at the same time energy consumption will also increase.

Hydrotreating Options

• HDT heavy naptha pre-cat reforming is very common• HDT of FCC napths becoming more common and more sophisticated• 95 - 99% of sulfur may be removed• Saturation of olefins and aromatics possible by typically avoided because of

octane loss

Diesel Hydrotreating Technologies

• Tightening sulfur specs have stimulated massive investment in new HDT technologies

• 95 - 99% sulphur typically removed

175174

• HDT improves cetane number and saturates some olefins and aromatics• HAD techs have evolved to saturate aromatics and eliminate sulfur• GTL technologies also evolving to produce zero - sulfur synthetic diesels.

Resid/VGO Hydrotreating Technologies

• RDS was rare outside of Japan (Belgium, Kuwait, S. Korea, UK, US also have)• FCC feed (VGO) pretreatment more common, resulting in lower - sulfur light

and middle distillate output• May also be considered mild hydrocracking depending on level of conversion

Growth in World HDT Capacity

• World HDT capacity grew from 24.9 mb/d in 1985 to 40.5 mb/d in 2003 -a 2.7% increase per year.

• CDU capacity grew at only 0.7% / year • Further expansions expected with many markets working to improve fuel

quality.• Automakers ask for "as close to zero - sulfur as soon as possible"

A hydrotreater unit specifically employed to remove sulphur from, various feedstocks, is called a Hydro De-Sulphurisation Unit (HDS). The H consumption, 2

and consequently the energy requirement, significantly increase in the order naphtha (0.05% H ), distillate (0.3% H ) and residue hydrotreating (1.8% H ). Table 2 2 2

16 shows the utility requirements for different hydrotreatments.

Table 4.16 - Utilities requirement of Hydrotreater

Hydrotreaters use a considerable amount of energy directly (fuel, steam, electricity) and indirectly (hydrogen).

Various alternatives are demonstrated at refineries around the world, including the oxidative desulfurization process (Valero's Krotz Springs, Louisiana) and the S Zorb process at Philip's Borger (TX). The S Zorb process is a sorbent operated in a fluidized bed reactor. Philips Petroleum Co. claims a significant reduction in hydrogen consumption to produce low-sulfur gasoline and diesel (Gislason, 2001). A cursory comparison of the characteristics of the S Zorb process and that of selected hydrotreaters suggests a lower fuel and electricity consumption, but increased water consumption.

Fuel (MJ/t)

Electricity (kWh/t)

Steam consumed

(kg/t)

Cooling water (m3/t,

DT=10°C)

Wash water (kg/t)

H2

(kg/t)

Naphtha processed

200-350

5-10

10-60

2-3

40-50 1-15

Distillate processed

300-500

10-20

60-150

2-3

30-40 1-15

Residue processed 300-800

10-30 60-150 2-3 30-40 10-100

Hydroconversion

600-1000

50-110

200-300 (steam

produced)

2-10

- -

Note:Hydroconversion is an exothermic reaction and the heat generated in the reactor system is partially recovered in the feed product exchanger.

i Energy Conservation Options

Installation of a multivariable predictive control. MPC system was demonstrated on a hydrotreater at a SASOL refinery in South Africa. The MPC aimed to improve the product yield while minimizing the utility costs. The implementation of the system led to improved yield of gasoline and diesel, reduction of flaring, and a 12% reduction in hydrogen consumption and an 18% reduction in fuel consumption of the heater (Taylor et al., 2000). Fuel consumption for the reboiler increased to improve throughput of the unit. With a payback period of 2 months, the project resulted in improved yield and in direct and indirect i.e., reduced hydrogen consumption and energy efficiency improvements.

Case Study 21 : Improvement of heat recovery system in Vacuum gas oil hydrotreater unit

Brief

The existing vacuum gas oil desulfurization unit cools the reaction products to separate them into gas, including recycling gas, and oil, and then reheats the oil for fractionation. The amount of heat dissipated at this condensing cooler is great. To recover a portion of this heat loss on one hand, and to overcome the increasing fouling of the combined feed heat exchanger which increases restriction on throughput on the other, the heat recovery system of the entire plant was improved and a new hot separator was installed.

Installation of a hot separator/heat exchanger

1) A hot separator was installed to reduce the heat loss at the effluent cooling condenser.

2) The combined heat exchanger system was expanded to increase heat recovery from the reactor effluent.

3) A preheater was added to the charge oil system to increase heat recovery from the fractionator bottom.

Improvement effects and system flow

01) The temperature at the inlet to the reactor charge heater has risen from 323 C to 0344 C.

02) The temperature at the fractionator charge heater has risen from 230 C to 0261 C.

3) The throughput has increased because of the reduced loads on the heaters.

Energy saving effects

Investment amount : Rs 200 million Improvement effect : Rs 87.2 million/year Investment payback : 2.3 years

After improvement

Fuel consumption - heavy fuel oil equivalent 7,300 kl/y reduction

Fuel consumption - crude oil equivalent 7,738 kl/y reduction

177176

referred to as a sulfuric acid alkylation unit (SAAU) or a hydrofluoric alkylation Unit, (HFAU). However, oil refinery employees may simply refer to the unit as the Alkyl or Alky unit. The catalyst is able to protonate the alkenes (propylene, butylenes) to produce reactive carbocations, which alkylate isobutene. The reaction

0is carried out at mild temperatures (0 and 30 C) in a two phase reaction. It is important to keep a high ratio of isobutene to olefin at the point of reaction to prevent side reactions that lead to a lower octane product, so the plants have a high recycle of isobutene back to feed. The phases separate spontaneously, so the acid phase is vigorously mixed with the hydrocarbon phase to create sufficient contact surface.

The product is called alkylate and is composed of a mixture of high octane, branched chain paraffinic hydrocarbons (mostly isopentane and isooctane). Alkylate is a premium gasoline blending stock because it has exceptional antiknock properties.

The octane number of the alkylate depends mainly upon the kind of olefins used and upon operating conditions. For example, isooctane results from combining butylenes with isobutene and has an octane rating of 100 by definition. As there are other products in the alkylate, so the octane rating will vary accordingly.

Most crude oils conytain only 10 to 40 percent of their hydrocarbon constituents in the gasoline range, so refineries use a fluid catalytic cracking process to convert high molecular weight hydrocarbons into smaller and more volatile compounds. Polymerization converts small gaseous olefins into liquid gasoline size hydrocarbons. Alkylation processes transform small olefin and iso paraffin molecules into larger iso-paraffins with a high octane number.

The summary of the utility consumptions in the two techniques currently used in the alkylation processes is given in the Table 4.17.

Table 4.17 Estimated utilities and chemical consumption for the various alkylation techniques

Energy Conservation Opportunities

i Feedstock upgradation by selective hydrogenation

The naphtha hydrotreatment or isomerisation (e.g. hydrogenation of butadiene, isomerisation of 1-butene to 2-butene) helps the alkylation units to reduce the acid losses and consequently the waste generation. As consequence, the amount of caustic consumption is decreased. The reduction in acid and caustic consumption depends on the feed diene content, which varies widely at different refineries.

Alkylation techniqueValues per tonne of alkylate produced

Sulphuric acid

Hydrofluoric

UtilitiesElectricity (kWh)

4

20 – 65

Fuel (MJ) n.a. 1000 – 3000Steam (kg) 830 100 – 1000Cooling water (m3)

(DT = 11 °C)

72

62

Industrial water (m3) 0.08

Case Study 22 : Rotation control of the recycle gas compressor in Heavy oildirect hydrotreater unit

Brief

The recycle gas of this unit is pressurized by the recycle gas compressor and loses pressure as it passes through the reactor, heat exchangers and control valves. If it is possible to operate the unit with the control valves, the major contributor to the pressure drop, nearly fully open, the power consumption of the compressor could be reduced. The improvement herein explained realized energy saving by controlling r.p.m. of the compressor in operation to reduce pressure drops across control valves

The pressure loss at the control valves accounts for 17% of all losses in this system when the valves are 80% open. Control valves, if operated in full open, reduce most efficiently the power consumption required. However, in actual operations, RPM. of the compressor has been controlled so that control valves are 90 % open to accommodate the fluctuation of the process

Energy savings

Investment amount (A) : a set of microcomputers: Rs 4.8 million, Improvement effect (B) : Rs 24.4 million/yearInvestment payback (A/B ) : 3 months

4.5.9 Alkylation

Alkylation is the transfer of an alkyl group from one molecule to another. The alkyl group may be transferred as an alkyl carbocation, a free radical, a carbanion or a carbine (or their equivalents).

Alkylating agents are widely used in chemistry because the alkyl group is probably the most common group encountered in organic molecules.

In oil refining contexts, alkylation refers to a particular alkylation of isobutene with olefins. It is a major aspect of the upgrading of petroleum.

Options for Alkylation

It depends upon the type of alkylating agents

i Nucleophilic alkylating agentsii Electrophilic alkylating agentsiii Radical alkylating agentsiv Carbene alkylating agents

In a standard oil refinery process, isobutene is alkylated with low molecular weight alkenes (primarily a mixture of propylene and butylenes) in the presence of a strong acid calatyst, either sulphuric acid or hydrofluoric acid. In an oil refinery it is

Before

improvement

After

improvement Effect

Steam consumption (t/h) 32.8 t/h 30.6 t/h 2.2 t/h reductionSteam consumption (t/y) 18,400 t/y reductionCrude oil

equivalent

1,582

kl/y

reduction

179178

ii Implementation of ACS

Motiva's Convent (Louisiana) refinery implemented an advanced control system for their 100,000 bpd sulfuric acid alkylaiton plant. The software package integrates information from chemical reactor analysis, pinch analysis, information on flows, and information on energy use and emissions to optimize efficient operation of the plant. The system aims to increase product yield by approximately 1%, reduce electricity consumption by 4.4%, reduce steam use by 2.2%, reduce cooling water use by 4.9%, and reduce chemicals consumption by 5-6% (caustic soda by 5.15, sulfuric acid by 6.4%) (U.S.DOE-OIT, 2000). The companies offering alkylation controls are ABB Simcon, Aspen technology, Emerson, Honeywell, Invensys, and Yokogawa. The controls typically result in cost savings of $0.10 to $0.20/ bbl of feed with paybacks of 6 to 18 months.

4.5.10 Visbreaking

Visbreaking/ thermal cracking is one of the oldest conversion processes to upgrade 0heavy oil fractions. The fuel stock is heated above 500 C and then fed to a reaction

chamber which is kept at a presence of about 9.65 bar (g).

Options of Visbreaking

i Coil Visbreaking: The term coil (or furnace) visbreaking is applied to units where the cracking process occurs in the furnace tubes (or "coils") . Material exiting the furnace is quenched to halt the cracking reactions: frequently this is achieved by heat exchange with the virgin material being fed to the furnace, which in turn is a good energy efficiency step, but sometimes a stream of cold oil (usually gas oil) is used to the same effect. The gas oil is recovered and re-used. The extent of the cracking reaction is controlled by regulation of the speed of flow of the oil through the furnace tubes. The quenched oil then passes to a fractionator where the products of the cracking (gas, LPG, gasoline, gas oil and tar) are separated and recoverd.

ii Soaker Visbreaking:In soaker visbreaking, the bulk of the cracking reaction occurs not in the furnace but in a drum located after the furnace called the soaker. Here the oil is held at an elevated temperature for a pre-determined period of time to allow cracking to occur before being quenched. The oil then passes to a fractrionator. In soaker visbreaking, lower temperatures are used than in coil visbreaking. The comparatively long duration of the cracking reaction is used instead.

Process Options

Visbreaker tar can be further refined by feeding it to a vacuum fractionator. Here additional heavy gas oil may be recovered and routed either to catalytic cracking, hydrocracking or thermal cracking units on the refinery. The vacuum - flashed tar (sometimes referred to as pitch) is then routed to fuel oil blending. In a few refinery locations, visbreaker tar is routed to a delayed coker for the production of certain specialist cokes such as anode coke or needle coke.

Soaker visbreaking versus coil visbreaking

From the standpoint of yield, there is little or nothing to choose between the two approaches. However, each offers significant advantages in particular situations:

0" Coil cracking uses higher furnace outlet temperatures (470-500 C) and reaction times from one to three minutes, while soaker cracking uses lower

0furnace outlet temperatures (430 - 440 C) and longer reaction times. The product yields and properties are similar.

" For visbreaking, fuel consumption accounts for about 80% of the operating costs with a net fuel consumption of 1-1.5% w/w on feed. Fuel requirements for soaker visbreaking are about 30 - 35% lower.

" De-coking: The cracking reactions forms petroleum coke as a byproduct. In coil visbreaking, this lays down in the tubes of the furnace and will eventually lead to fouling or blocking of the tubes.

The same will occur in the drum of a soaker visbreasker, though the lower temperature used in the soaker drum lead to fouling at a much slower rate. Coil visbreakers therefore require frequent decoking. This is quite labour intensive. Soaker drums require far less frequent attention but while taken out of service normally requires a complete halt to the operation which is the more disruptive activity and will vary from refinery to refinery.

" Fuel Economy: The lower temperatures used in the soaker approach mean that these units use less fuel. In cases where a refinery buys fuel to support process operations, any savings in fuel consumption could be extremely valuable. In such cases, soaker visbreaking may be advantageous.

The typical utilities consumption for a visbreaker are: -

Table 4.18 Utility consumptions for a visbreaker

The most important factor in controlling the cracking severity should always be stability and viscosity of the visbroken residue fed to the fuel oil pool. In general, an increase in the temperature or residence time results in an increase in severity. Increased severity produces higher gas-plus-gasoline yield and at the same time a cracked residue (fuel oil) of lower viscosity. Excessive cracking, however, leads to an unstable fuel oil, resulting in sludge and sediment formation during storage. Thermal cracking units to upgrade atmospheric residue have conversion levels of 35-45% and the viscosity of the atmospheric residue is reduced.

Fuel (MJ/t) 400 – 800 Electricity (kWh/t) 10 – 15 Steam consumed (kg/t) 5 – 30

Cooling water (m3/t, DT = 10°C) 2 - 10

Note: the power consumption given is for “furnace” cracking.

181180

• UTILITIES

4.5.11 Steam Generation and Distribution

An estimated 30% of all onsite energy use in Refineries is in the form of steam. The refining industry uses steam for a wide variety of purposes, the most important being process heating, drying or concentrating, steam cracking, and distillation. Steam can be generated through waste heat recovery from processes, cogeneration, and boilers. In most refineries, steam will be generated by all three sources, while some smaller refineries may not have cogeneration equipment installed. While the exact size and use of a modern steam systems varies greatly, there is an overall pattern that steam systems follow, as shown in Figure 3.

Whatever the use or the source of the steam, efficiency improvements in steam generation, distribution and end-use are possible. A recent study by the U.S. Department of Energy estimates the overall potential for energy savings in petroleum refineries at over 12% (U.S. DOE, 2002).

i Boilers

a Boiler Feed Water Preparation. Depending on the quality of incoming water, the boiler feed water (BFW) needs to be pre-treated to a varying degree. Various technologies may be used to clean the water. A new technology is based on the use of membranes. In reverse osmosis (RO), the pre-filtered water is pressed at increased pressure through a semi-permeable membrane. Reverse osmosis and other membrane technologies are used more and more in water treatment (Martin et al., 2000).

The Flying J refinery in North Salt Lake Utah installed a RO-unit to remove hardness and reduce the alkalinity from boiler feed water, replacing a hot lime water softener, resulting in reduced boiler blowdown from 13.3% to 1.5% of steam produced and reduced chemical use, maintenance, and waste disposal costs. With an investment of $350,000 and annual benefits of approximately $200,000, the payback period amounted to less than 2 years.

b Improved Process Control. Flue gas monitors are used to maintain optimum flame temperature, and to monitor CO, oxygen and smoke. The oxygen content of the exhaust gas is a combination of excess air deliberately introduced to improve safety or reduce emissions and air infiltration (air leaking into the boiler).

Figure 4.3 Schematic presentation of a steam production and distribution system

By combining an oxygen monitor with an intake airflow monitor, it is possible to detect small leaks. Using a combination of CO and oxygen readings, it is possible to optimize the fuel/air mixture for high flame temperature and thus the best energy efficiency and low emissions. The payback of improved process control is approximately 0.6 years (IAC, 1999).

c Reduce Flue Gas Quantities. Often, excessive flue gas results from leaks in the boiler and the flue, reducing the heat transferred to the steam, and increasing pumping requirements. These leaks are often easily repaired. Savings amount to 2-5% (OIT, 1998). This measure consists of a periodic repair based on visual inspection. The savings from this measure and from flue gas monitoring are not cumulative, as they both address the same losses.

d Reduce Excess Air. The more air is used to burn the fuel, the more heat is wasted in heating air. Air slightly in excess of the ideal stoichometric fuel/air ratio is required for safety, and to reduce NOx emissions, and is dependent on the type of fuel. For gas and oil-fired boilers, approximately 15% excess air is adequate (OIT, 1998; Ganapathy, 1994). Poorly maintained boilers can have up to 140% excess air. Reducing this back down to 15% even without continuous automatic monitoring would save 8%.

e Maintenance. A simple maintenance program to ensure that all components of the boiler are operating at peak performance can result in substantial savings. The absence of a good maintenance system can end up costing a steam system up to 20-30% of initial efficiency over 2-3 years. On average, the possible energy savings are estimated at 10% (DOE, 2001a). Improved maintenance may also reduce the emission of criteria air pollutants.

Fouling of the fireside of the boiler tubes or scaling on the waterside of the boiler should also be controlled. Tests show that a soot layer of 0.03 inches (0.8 mm) reduces heat transfer by 9.5%, while a 0.18-inch (4.5 mm) soot layer reduces heat transfer by 69% (CIPEC, 2001). For scaling, 0.04 inches (1 mm) of buildup can increase fuel consumption by 2% (CIPEC, 2001). Moreover, scaling may result in tube failures.

f Recover Heat From Flue Gas. Heat from flue gases can be used to preheat boiler feed water in an economizer. While this measure is fairly common in large boilers, there is often still potential for more heat recovery. The limiting factor for flue gas heat recovery is the economizer wall temperature that should not drop below the dew point of acids in the flue gas. One percent of fuel use is saved for every 25°C reduction in exhaust gas temperature. (Ganapathy, 1994). Since exhaust gas temperatures are already quite low, limiting savings to 1% across all boilers, with a payback of 2 years (IAC, 1999).

g Recover Steam From Blowdown. When the water is blown from the high-pressure boiler tank, the pressure reduction often produces substantial amounts of steam. This steam is low grade, but can be used for space heating and feed water preheating. For larger high-pressure boilers, the losses may be less than 0.5%. It is estimated that this measure can save 1.3% of boiler fuel use for all boilers below 100 MMBtu/hr (approximately 5% of all boiler capacity in refineries). The payback period of blowdown steam recovery will vary between 1 and 2.7 years (IAC, 1999).

183182

h Reduce Standby Losses. In refineries often one or more boilers are kept on standby in case of failure of the operating boiler. The steam production at standby can be reduced to virtually zero by modifying the burner, combustion air supply and boiler feed water supply. By installing an automatic control system the boiler can reach full capacity within 12 minutes. Installing the control system and modifying the boiler can result in energy savings up to 85% of the standby boiler, depending on the use pattern of the boiler.

ii Steam Distribution

When designing new steam distribution systems, it is very important to take into account the velocity and pressure drop (Van de Ruit, 2000). This reduces the risk of oversizing a steam pipe, which is not only a cost issue but would also lead to higher heat losses. However, it may be too expensive to optimize the system for changed steam demands. Still, checking for excess distribution lines and shutting off those lines is a cost-effective way to reduce steam distribution losses. Other maintenance measures for steam distribution systems are described below.

a Improve Insulation: Crucial factors in choosing insulating material include low thermal conductivity, dimensional stability under temperature change, resistance to water absorption, and resistance to combustion. New materials insulate better, and have a lower heat capacity. Savings of 6-26% can be achieved if this improved insulation is combined with improved heater circuit controls. The shell losses of a well-maintained boiler should be less than 1%.

b Maintain Insulation. It is often found that after repairs, the insulation is not replaced. In addition, some types of insulation can become brittle, or rot. As a result, energy can be saved by a regular inspection and maintenance system (CIBO, 1998). Exact energy savings and payback periods vary with the specific situation in the plant.

Case Study 23: Replacing the Damaged Insulation to arrest Heat Losses.

Brief

In a gas based Petrochemical plant, the VHP steam is supplied from utility boilers (UB#2 & UB#3) to the process plants GCU and LPG. The length of the steam headers to these plants from the Utility Plant is approximately one kilometer. The discussions of the audit team with shift-in charge and respective Heads of the Plants revealed that the temperature drop across the pipeline has been significantly

0high as a result the steam temperature at the battery limit of LPG (470 C) and GCV 0(460 C) are lower.

The high surface temperatures of insulated steam headers / pipes indicate the damaged or inadequate insulation. For the above-mentioned areas, it was recommended to replace the insulation to arrest the heat losses. Since the measured surface temperatures are significantly higher than the normal temperature, the anticipated energy savings will be substantial and the payback period will be attractive (less than a year). Table gives the cost-benefit analysis of replacing the insulation.

Energy Savings

c Improve Steam Traps. Using modern thermostatic elements, steam traps can reduce energy use while improving reliability. The main advantages offered by these traps are that they open when the temperature is very close to that of the saturated steam (within 2°C), purge non-condensable gases after each opening, and are open on startup to allow a fast steam system warm-up. These traps are also very reliable, and useable for a wide variety of steam pressures (Alesson, 1995). Energy savings will vary depending on the steam traps installed and state of maintenance.

d Maintain Steam Traps. A simple program of checking steam traps to ensure that they operate properly can save significant amounts of energy. If the steam traps are not regularly monitored, 15-20% of the traps can be malfunctioning. In some plants, as many as 40% of the steam traps were malfunctioning. Energy savings for a regular system of steam trap checks and follow-up maintenance is estimated at up to 10% (OIT, 1998; Jones 1997; Bloss, 1997) with a payback period of 0.5 years.

e Monitor Steam Traps Automatically. Attaching automated monitors to steam traps in conjunction with a maintenance program can save even more energy, without significant added cost. This system is an improvement over steam trap maintenance alone, because it gives quicker notice of steam trap malfunctioning or failure. Using automatic monitoring is estimated to save an additional 5% over steam trap maintenance, with a payback of 1 year (Johnston, 1995; Jones, 1997).

Annual reduction in heat loss

Equivalent annual monetary saving

Approximate cost of insulation

Simple payback period

Area Identified Surface

Temp oC

million Kcal

Rs. lacs

Rs. lacs

Months

HP steam pipeline

85

9.91

0.13

0.03

2.24

VHP steam header

70

21.96

0.30

0.09

3.79

Pipeline opposite compressor

200

214.89

2.92

0.10

0.41

VHP line near 90-JBA-207 75 7.13 0.10 0.03 3.10

Inlet vertical pipe

60

2.53

0.03

0.02

6.57

Drain pipe

75

7.16

0.10

0.03

3.10

HP line near condensate drum

91

11.64

0.16

0.03

1.90

Condensate header

75

7.16

0.10

0.03

3.10

HP header at B/l

90

11.34

0.15

0.03

1.95

HP line near PRDS

85

9.90

0.13

0.03

2.24

246.76 3.5 0.22 0.76

185184

Case Study 24 : Replacement of Damaged Steam Traps.

Brief

Study of Steam Traps In a gas based Petrochemical plant, there are over 1,000 steam traps in different sections of the plant for varying applications on the steam mains, condensate lines, and process requirement. The traps installed are of different types - Thermodynamic, Bucket, and Orifice, and of different sizes.

Field testing of steam traps During an energy audit study, about 170 representative steam traps were tested using the portable steam trap tester "TRAPMAN", from different sections of the plant, viz., GCU, LPG, Butene - 1, Boiler & Power Plant, and GPU. The working condition of the traps in terms of Good / Blowing / Chocked / Low Temperature / Bypass was measured using the portable instrument.

The findings of the steam traps performance evaluation are summarized below :

Performance of Steam Traps

As can be observed from the table, only 48% of the traps tested are in good working conditions. The remaining 52% of the traps are either blocked (chocked), leaking, or at low temperature. The following measures are recommended to improve the performance of the steam traps and reduce the steam losses and associated energy losses. It is recommended to replace all the 89 faulty steam traps immediately to arrest steam leakage and losses. The anticipated energy savings, investment required, and approximate payback period are as follows:

Energy Savings

S. No.

Item No. of traps

%

1 No. of traps in good condition 81 48 2. No. of traps blowing / leaking 44 26 3. No. of traps chocked 16 9 4. No. of traps indicating low temperature 29 17 Total No. of traps studied 170 100

Description Unit Value

No. of steam traps leaking nos. 44

Estimated steam leakage per trap

kg/hr

7.5

Enthalpy of leakage steam

kCal/kg

750

Heat loss due to leakage

kCal/hr

247500

NCV of natural gas

kCal/sm3

8176

Boiler efficiency % 90

Loss of natural gas sm3/hr 33.64

Operational hours per annum

hrs

7200

Annual natural gas loss

sm

3

242172

Cost of natural gas

Rs/sm3

10

Annual monetary savings by stopping leakages

Rs. lacs

24

Anticipated Investment Rs. lacs 4.5

Payback period months 2

The traps which are chocked or indicated as low temperature needs to be repaired immediately to let the condensate flow smoothly out of the system and to ensure effective heat transfer. Though it is difficult to precisely estimate the achievable energy savings, it can be concluded that by ensuring effective operation of the remaining 45 traps, fuel savings worth more than Rs.10 lac per annum can be easily achieved. The investment required towards replacement of parts of the traps or replacement the traps itself can be paid back in less than an year. The improved steam trap performance also would ensure effective heat transfer hence enhanced throughput. Therefore, the overall savings that can accrued due to satisfactory functioning of traps would be many fold.

f Repair Leaks. As with steam traps, the distribution pipes themselves often have leaks that go unnoticed without a program of regular inspection and maintenance. In addition to saving up to 3% of energy costs for steam production, having such a program can reduce the likelihood of having to repair major leaks (OIT, 1998).

Case study 25 : Arresting the Steam Leakages

Brief

In one of the gas based Petrochemical plant the steam distribution network was studied in detail to identify steam leakage points and quantify the leakages. All the process sections, utilities, and headers were covered in the study. Leakages were identified from flanges, valves, joints, etc. The nature of leakage varies from medium to heavy in many places. The steam leakage points were identified during the survey and listed below:

It is recommended to arrest the steam leakages from the above mentioned areas immediately by replacing the damaged valves, pipe fittings, flanges, traps, etc. The resultant monetary savings and payback period are as follows:

Energy Savings

Particulars

No of steam leakage points identified

20

Steam leakage per point 7.5 kg/hr

Working hours per annum 7200 hr

Steam savings due to arrest of leakages

1,080 Tonnes/annum

Equivalent natural gas savings 392,000 SM /annum

Annual monetary savings Rs.9 lac

Investment required Rs.5 lac

Simple payback period 7 months

187186

As can be seen from the table above, by attending to steam leakages, monetary savings worth Rs.9 lac can be achieved with an investment of Rs.5 lac towards replacement of damaged pipe sections. The payback works out to be 7 months.

g Recover Flash Steam. When a steam trap purges condensate from a pressurized steam distribution system to ambient pressure, flash steam is produced. This steam can be used for space heating or feed water preheating (Johnston, 1995).

h Return Condensate. Reusing the hot condensate in the boiler saves energy and reduces the need for treated boiler feed water. The substantial savings in energy costs and purchased chemicals costs makes building a return piping system attractive. Care has to be taken to design the recovery system to reduce efficiency losses (van de Ruit, 2000). Maximum energy savings are estimated at 10% (OIT, 1998) with a payback of 1.1 years (IAC, 1999) for those sites without or with insufficient condensate return. An additional benefit of condensate recovery is the reduction of the blowdown flow rate because boiler feedwater quality has been increased.

4.5.12 Compressors and Compressed Air

Compressors consume about 12% of total electricity use in refineries. The major energy users are compressors for furnace combustion air and gas streams in the refinery. Compressed air is probably the most expensive form of energy available in an industrial plant because of its poor efficiency. Typically, efficiency from start to end-use is around 10% for compressed air systems (LBNL et al., 1998). In addition, the annual energy cost required to operate compressed air systems is greater than their initial cost. Many opportunities to reduce energy in compressed air systems are not prohibitively expensive; payback periods for some options are extremely short - less than one year.

i Maintenance. Inadequate maintenance can lower compression efficiency, increase air leakage or pressure variability and lead to increased operating temperatures, poor moisture control and excessive contamination. Better maintenance will reduce these problems and save energy:

• Blocked pipeline filters increase pressure drop. A 2% reduction of annual energy consumption in compressed air systems is projected for more frequent filter changing (Radgen and Blaustein, 2001).

• Poor motor cooling can increase motor temperature and winding resistance, shortening motor life, in addition to increasing energy consumption. In addition to energy savings, this can help avoid corrosion and degradation of the system.

• Inspect fans and water pumps for peak performance.

• Inspect drain traps periodically to ensure they are not stuck in either the open or closed position and are clean. According to vendors, inspecting and maintaining drains typically has a payback of less than 2 years (Ingersoll-Rand, 2001).

• Maintain the coolers on the compressor to ensure that the dryer gets the lowest possible inlet temperature (Ingersoll-Rand, 2001).

• Check belts for wear and adjust them. A good rule of thumb is to adjust them every 400 hours of operation.

• Check water-cooling systems for water quality (pH and total dissolved solids), flow and temperature. Clean and replace filters and heat exchangers as per manufacturer's specifications.

• Minimize leaks (see also Reduce leaks section, below).

• Specify regulators that close when failed.

• Applications requiring compressed air should be checked for excessive pressure, duration or volume. They should be regulated, either by production line sectioning or by pressure regulators on the equipment itself.

ii Monitoring. Proper monitoring and maintenance can save a lot of energy and money in compressed air systems. Proper monitoring includes the following (CADDET, 1997):

• Pressure gauges on each receiver or main branch line and differential gauges across dryers, filters, etc.

• Temperature gauges across the compressor and its cooling system to detect fouling and blockages

• Flow meters to measure the quantity of air used• Dew point temperature gauges to monitor the effectiveness of air dryers• kWh meters and hours run meters on the compressor drive• Compressed air distribution systems when equipment has been

reconfigured.• Check for flow restrictions of any type in a system, pressure rise resulting

from resistance to flow increases the drive energy on the compressor by 1% of connected power for every 2 psi of differential (LBNL et al., 1998; Ingersoll- Rand, 2001).

iii Reduce leaks in pipes and equipment. Leaks can be a significant source of wasted energy. A typical plant that has not been well maintained could have a leak rate between 20 to 50% of total compressed air production capacity (Ingersoll Rand, 2001). Overall, a 20% reduction of annual energy consumption in compressed air systems is projected for fixing leaks (Radgen and Blaustein, 2001).

iv Reducing the Inlet Air Temperature Reducing the inlet air temperature reduces energy used by the compressor. In many plants, it is possible to reduce inlet air temperature to the compressor by taking suction from outside the building. As a rule of thumb, each 3°C will save 1% compressor energy use (CADDET, 1997; Parekh, 2000).

v Maximize Allowable Pressure Dew Point at Air Intake. Choose the dryer that has the maximum allowable pressure dew point and best efficiency. A rule of thumb is that desiccant dryers consume 7 to 14% of the total energy of the compressor, whereas refrigerated dryers consume 1 to 2% as much energy as the compressor (Ingersoll Rand, 2001). Consider using a dryer with a floating dew point. Note that where pneumatic lines are exposed to freezing conditions, refrigerated dryers are not an option.

189188

vi Controls. The objective of any control strategy is to shut off unneeded compressors or delay bringing on additional compressors until needed. All compressors that are on should be running at full load. Positioning of the control loop is also important; reducing and controlling the system pressure downstream of the primary receiver results in reduced energy consumption of up to 10% or more (LBNL et al., 1998).

• Start/stop (on/off) is the simplest control available and can be applied to small reciprocating or rotary screw compressors.

• Load/unload control, or constant speed control, allows the motor to run continuously but unloads the compressor when the discharge pressure is adequate. In most cases, unloaded rotary screw compressors still consume 15 to 35% of full-load power when fully unloaded, while delivering no useful work (LBNL et al., 1998).

Modulating or throttling controls allows the output of a compressor to be varied to meet flow requirements by closing down the inlet valve and restricting inlet air to the compressor. Changing the compressor control to a variable speed control saves up to 8% per year (CADDET, 1997).

vii Properly Sized Regulators. Regulators sometimes contribute to the biggest savings in compressed air systems. By properly sizing regulators, compressed air will be saved that is otherwise wasted as excess air.

viii Sizing Pipe Diameter Correctly. Inadequate pipe sizing can cause pressure losses, increase leaks, and increase generating costs. Pipes must be sized correctly for optimal performance or resized to fit the current compressor system. Increasing pipe diameter typically reduces annual energy consumption by 3% (Radgen and Blaustein, 2001).

ix Heat Recovery For Water Preheating. As much as 80 to 93% of the electrical energy used by an industrial air compressor is converted into heat. In many cases, a heat recovery unit can recover 50 to 90% of the available thermal energy for space heating, industrial process heating, water heating, makeup air heating, boiler makeup water preheating, industrial drying, industrial cleaning processes, heat pumps, laundries or preheating aspirated air for oil burners (Parekh, 2000). Paybacks are typically less than one year.

x Adjustable Speed Drives (ASDs). Implementing adjustable speed drives in rotary compressor systems has saved 15% of the annual compressed air energy consumption (Radgen and Blaustein, 2001).

xi High Efficiency Motors. Installing high efficiency motors in compressor systems reduces annual energy consumption by 2%, and has a payback of less than 3 years (Radgen and Blaustein, 2001).

Case Study 26 : Replacement of reciprocating air compressor

In a Petroleum refinery, there were 4 reciprocating air compressors, out of which 2 used to run to cater instrument air and service air requirement in the original refinery configuration. These compressors were lower energy efficient and obsolete in nature and had problems of frequent breakdowns and maintenance.

With the addition of more secondary units, air requirement had increased. To meet increased air requirement compressor with higher energy efficiencies have been

3installed. Thus, new Centrifugal Air Compressors of capacity 5000 NM /Hr, 650 KW each were provided replacing four numbers of old reciprocating compressors. ith the provision of this centrifugal compressor savings of ~ 100 SRFT per compressor has been achieved.

4.5.13 Process Heaters

Over 60% of all fuel used in the refinery is used in furnaces and boilers. The average thermal efficiency of furnaces is estimated at 75-90%. Accounting for unavoidable heat losses and dewpoint considerations, the theoretical maximum efficiency is around 92% (HHV) (Petrick and Pellegrino, 1999). This suggests that on average a 10% improvement in energy efficiency can be achieved in furnace and burner design.

The efficiency of heaters can be improved by improving heat transfer characteristics, enhancing flame luminosity, installing recuperators or air-preheaters, and improved controls. New burner designs aim at improved mixing of fuel and air and more efficient heat transfer. Many different concepts are developed to achieve these goals, including lean-premix burners (Seebold et al., 2001), swirl burners (Cheng, 1999), pulsating burners (Petrick and Pellegrino, 1999) and rotary burners (U.S. DOE-OIT, 2002e). Also, furnace and burner design has to address safety and environmental concerns.

i Maintenance

Regular maintenance of burners, draft control and heat exchangers is essential to maintain safe and energy efficient operation of a process heater.

Draft Control. Badly maintained process heaters may use excess air. This reduces the efficiency of the burners. Excess air should be limited to 2-3% oxygen to ensure complete combustion.

Valero's Houston refinery has installed control systems to reduce excess combustion air at the three furnaces of the CDU. The control system allows running the furnace with 1% excess oxygen instead of the regular 3-4%. The system has not only reduced energy use by 3 to 6% but also reduced NOx emissions by 10-25%, and enhanced the safety of the heater.

ii Air Preheating

Air preheating is an efficient way of improving the efficiency and increasing the capacity of a process heater. The flue gases of the furnace are used to preheat the combustion air. Every 35°F drop in the exit flue gas temperature increases the thermal efficiency of the furnace by 1% (Garg, 1998). Typical fuel savings range between 8 and 18% and is typically economically attractive if the flue gas temperature is higher than 650°F and the heater size is 50 MMBtu/hr or more (Garg, 1998).

VDU. At a refinery in the United Kingdom, the temperature of the flue gas was reduced to 470°F. This led to energy cost savings of $109,000/year with a payback period of 2.2 years (Venkatesan and Iordanova, 2003).

iii New Burners

In many areas, new air quality regulation will demand refineries to reduce NOx and VOC emissions from furnaces and boilers. Instead of installing expensive selective catalytic reduction (SCR) flue gas treatment plants, new burner technology developed by ChevronTexaco, in collaboration with John Zink Co., for refinery applications based on the lean premix concept, reduces NOx emissions from 180 ppm to below 20 ppm.

Case Study 27 : Installation of High efficiency furnace in Hydro-finishingunit

Brief

In a refinery, the existing old furnace (with radiation section only) in HFU was replaced with new high efficiency furnace (with both radiation & convection section) and with Low NOx & low excess air burners.

Energy Savings

Investments : Rs. 200.00 LakhsFuel Savings : 215 MT of IFO /annum on full T'put OperationSavings : Rs. 19.40 Lakhs

4.514 Electric Motors

Electric motors are used throughout the refinery, and represent over 80% of all electricity use in the refinery. The major applications are pumps (60% of all motor use), air compressors (15% of all motor use), fans (9%), and other applications (16%).

Using a "systems approach" that looks at the entire motor system (pumps, compressors, motors, and fans) to optimize supply and demand of energy services often yields the most savings. For example, in pumping, a systems approach analyzes both the supply and demand sides and how they interact, shifting the focus of the analysis from individual components to total system performance. The measures identified below reflect aspects of this system approach including matching speed and load (adjustable speed drives), sizing the system correctly, as well as upgrading system components.

i Motor Optimization

a Sizing of Motors. Motors and pumps that are sized inappropriately result in unnecessary energy losses. Where peak loads can be reduced, motor size can also be reduced. Correcting for motor over sizing saves 1.2% of their electricity consumption, and even larger percentages for smaller motors (Xenergy, 1998).

b Higher Efficiency Motors. High efficiency motors reduce energy losses through improved design, better materials, tighter tolerances, and improved manufacturing techniques. With proper installation, energy efficient motors run cooler and consequently have higher service factors, longer bearing and insulation life and less vibration.

Typically, high efficiency motors are economically justified when exchanging a motor that needs replacement. The best savings are achieved on motors running for long hours at high loads. Replacing a motor with a high efficiency motor is often a better choice than rewinding a motor. The practice of rewinding motors currently has no quality or efficiency standards.

ii Power Factor. Inductive loads like transformers, electric motors and HID lighting may cause a low power factor. A low power factor may result in increased power consumption, and hence increased electricity costs. The power factor can be corrected by minimizing idling of electric motors, avoiding operation of equipment over its rated voltage, replacing motors by energy efficient motors and installing capacitors in the AC circuit to reduce the magnitude of reactive power in the system.

iii Voltage Unbalance. Voltage unbalance degrades the performance and shortens the life of three-phase motors. A voltage unbalance causes a current unbalance, which will result torque pulsations, increased vibration and mechanical stress, increased losses, motor overheating reducing the life of a motor. It is recommended that voltage unbalance at the motor terminals does not exceed 1%. For a 100 hp motor operating 8000 hours per year, a correction of the voltage unbalance from 2.5% to 1% will result in electricity savings of 9,500 kWh.

iv Adjustable Speed Drives (ASDS)/Variable Speed Drives (VSDs). ASDs better match speed to load requirements for motor operations. Energy use on many centrifugal systems like pumps, fans and compressors is approximately proportional to the cube of the flow rate. Hence, small reductions in flow that are proportional to motor speed can sometimes yield large energy savings. Paybacks for installing new ASD motors in new systems or plants can be as low as 1.1 years (Martin et al., 2000). The installation of ASDs improves overall productivity, controls product quality and reduces wear on equipment, thereby reducing maintenance cost.

Case study 28 : Installation of Variable Speed Drives for pumps in DM plant and CPU plant

Brief

The major pumps in DM water plant and condensate polishing units have recirculation lines along with valves in order to maintain the desired line pressure in view of variable requirement. This recirculation results in bypassing of excess water from the discharge line to the supply source. The pump is operated with the constant load since variations are controlled by recirculation valve.

The recirculation results in energy loss since the pump is operated on full load condition though there is variable requirement. The following table gives the measured water flows of discharge line and recirculation.

191190

193192

Energy Loss due to recirculation

It can be seen that on average about 33 % of energy is being lost due to recirculation.

The energy loss due to recirculation can be avoided by installing the variable speed drives (VSD) to the pumps. Installation of variable speed drives will enable the pumps only to discharge as per the requirement by sensing the pressure in the discharge line. After installation of VSD, the recirculation valves should be fully closed to achieve the energy savings.

Energy Savings

Considering the minimum energy savings to the tune of 25 % (present average loss is of 33%) the total energy savings achievable in the above three pumping systems estimated and tabulated below:

Pump ID code Pump discharge

flow, lps

Power, kW

Supply to users, lps

Recirculation flow, lps

Energy loss due to recirculation, kW

% loss to the total

Degasser water -32

PPP1A

71 59.7 37 34 27 45

Condensate feed pump- 32 P 102 A

62 55 50.5 11.5 10 18

Polished Condensate

transfer pump- 32 P 101 A

74.38

51.3

47.5

26.88

18

36

Total 166 55 33

Pump

ID code

No

.o

fp

um

ps

ins

tall

ed

No

.o

fp

um

ps

op

era

ted

Po

we

r,k

W

En

erg

ys

av

ing

s

An

nu

al

en

erg

ys

av

ing

s,

lak

hk

Wh

An

nu

al

co

st

sa

vin

gs

,R

s.

lak

h

Inv

es

tme

nt

req

uir

ed

,R

s.

lak

hs

Degasser water -

32 PPP1A 3

1

59.7

15

1.20

5.40

5.00

Condensate feed

pump-

32 P 102 A

3 1 55 14 1.12 5.04 5.00

Polished

Condensate

transfer pump-

32 P 101 A

3

1

51.3

13

1.04

4.68 5.00

Total 166 42 3.36 15.12 15.00

Reduction in power consumption : 42 kWOperating hours : 8000 per yearEnergy savings per annum : 3.36 lakh kWhAnnual cost savings (Rs.4.50/kWh) : Rs.15.12 lakhAnticipated Investment : Rs. 21 lakhPayback period : one year six months

v Variable Voltage Controls (VVCs). In contrast to ASDs, which have variable flow requirements, VVCs are applicable to variable loads requiring constant speed. The principle of matching supply with demand, however, is the same as for ASDs.

4.5.15 Pumps

In the petroleum refining industry, about 59% of all electricity use in motors is for pumps (Xenergy, 1998). This equals 48% of the total electrical energy in refineries, making pumps the single largest electricity user in a refinery. Pumps are used throughout the entire plant to generate a pressure and move liquids. Studies have shown that over 20% of the energy consumed by these systems could be saved through equipment or control system changes (Xenergy, 1998).

It is important to note that initial costs are only a fraction of the life cycle costs of a pump system. In general, for a pump system with a lifetime of 20 years, the initial capital costs of the pump and motor make up merely 2.5% of the total costs (Best Practice Programme, 1998). Depending on the pump application, energy costs may make up about 95% of the lifetime costs of the pump.

i Operations and Maintenance. Inadequate maintenance at times lowers pump system efficiency, causes pumps to wear out more quickly and increases costs. Better maintenance will reduce these problems and save energy. Proper maintenance includes the following (Hydraulic Institute, 1994; LBNL et al., 1999):

• Replacement of worn impellers.• Bearing inspection and repair.• Bearing lubrication once annually or semiannually.• Inspection and replacement of packing seals. • Inspection and replacement of mechanical seals. • Wear ring and impeller replacement. • Pump/motor alignment check.

Typical energy savings for operations and maintenance are estimated to be between 2 and 7% of pumping electricity use. The payback is usually one year (Xenergy, 1998; U.S. DOE-OIT, 2002c).

ii Monitoring. Monitoring in conjunction with operations and maintenance can be used to detect problems and determine solutions to create a more efficient system. Monitoring can determine clearances that need be adjusted, indicate blockage, impeller damage, inadequate suction, operation outside preferences, clogged or gas-filled pumps or pipes, or worn out pumps. Monitoring should include:

195194

• Wear monitoring• Vibration analyses• Pressure and flow monitoring• Current or power monitoring• Differential head and temperature rise across the pump/ thermodynamic

monitoring• Distribution system inspection for scaling or contaminant build-up

iii Reduce Need. Holding tanks can be used to equalize the flow over the production cycle, enhancing energy efficiency and potentially reducing the need to add pump capacity. In addition, bypass loops and other unnecessary flows should be eliminated. Energy savings may be as high as 5-10% for each of these steps (Easton Consultants, 1995).

Case study 29 : Optimisation of Cooling Water Flow

Brief

Three numbers of cooling water pumps were used to supply cooling water to refinery units. Excess flow /wastage of cooling water observed in AVU and DCU plant. The problem of cooling water system is not the flow but the low pressure of the cooling water, hence by stopping one of the cooling water pumps and optimizing cooling water in AVU and DCU and installation of one small booster pump of

2maintaining supply header pressure at 4.5 kg/cm can save 257 kW per hour, which is equivalent to 21.6 lakhs kwhr/year.

Energy savings

Investment costs : Rs. 10 lakhs (for the installation of booster pump)Savings achieved : Rs. 15 lakhsPay back period : 8 months

iv More Efficient Pumps. According to Easton Consultants, 1995, pump efficiency may degrade 10 to 25% in its lifetime. Replacing a pump with a new efficient one saves between 2 to 10% of its energy consumption (Elliott, 1994).

v Correct Sizing Of Pump(s) (Matching Pump To Intended Duty). Pumps that are sized inappropriately result in unnecessary losses. Where peak loads can be reduced, pump size can also be reduced. Correcting for pump over sizing can save 15 to 25% of electricity consumption for pumping (Easton Consultants, 1995).

vi Use Multiple Pumps. Often using multiple pumps is the most cost-effective and most energy efficient solution for varying loads, particularly in a static head-dominated system. Installing parallel systems for highly variable loads saves 10 to 50% of the electricity consumption for pumping (Easton Consultants, 1995). Variable speed controls should also be considered for dynamic systems.

vii Trimming Impeller or Shaving Sheaves. If a large differential pressure exists at the operating rate of flow, the impeller diameter can be trimmed so that the pump does not develop as much head

Case study 30 : Trimming the Diameter of Pump Impeller

Brief

Salt Union Ltd. produces white salt by the multistage evaporation of brine. A by-product of the process is condensate, which is exported to a nearby power station to feed the boiler. Operational analysis showed that the pressure generated by the condensate export pump was considerably higher than was necessary. The high degree of throttling that was consequently needed had led to instability in the system, resulting in mal-operation and high maintenance costs.

Energy savings

Trimming the diameter of pump impeller resulted in reducing power required by the pump and also allowed a smaller motor to be fitted which further resulted in energy savings.

Potential users : Any user of pumpsInvestment costs : Rs. 20,000.00 Savings achieved -

(a) Energy Saving : Rs. 7,50,000.00(b) Savings in repair : Rs. 2,50,000.00

& maintenance

Payback period : 8 days

viii Controls. Remote controls enable pumping systems to be started and stopped more quickly and accurately when needed, and reduce the required labor. In addition to energy savings, the control system reduces maintenance costs and increases the pumping system's equipment life.

ix Adjustable Speed Drives (ASDs). ASDs better match speed to load requirements for pumps where, as for motors, energy use is approximately proportional to the cube of the flow rate. Hence, small reductions in flow that are proportional to pump speed may yield large energy savings. In addition, the installation of ASDs improves overall productivity, and product quality, and reduces wear on equipment, thereby reducing future maintenance costs.

x Avoid Throttling Valves. Extensive use of throttling valves or bypass loops may be an indication of an oversized pump. Variable speed drives or on off regulated systems always save energy compared to throttling valves (Hovstadius, 2002).

197196

xi Correct Sizing Of Pipes. Similar to pumps, undersized pipes also result in unnecessary losses. Increasing the pipe diameter may save energy but must be balanced with costs for pump system components. Correct sizing of pipes should be done at the design or system retrofit stages where costs may not be restrictive.

xii Replace Belt Drives. Inventory data suggests 4% of pumps have V-belt drives, many of which can be replaced with direct couplings to save energy (Xenergy, 1998). Savings are estimated at 1%.

xiii Precision Castings, Surface Coatings, Or Polishing. The use of castings, coatings, or polishing reduces surface roughness that in turn, increases energy efficiency. It may also help maintain efficiency over time. Energy savings for coating pump surfaces are estimated to be 2 to 3% over uncoated pumps (Best Practice Programme, 1998).

xiv Sealings. Seal failure accounts for up to 70% of pump failures in many applications (Hydraulic Institute and Europump, 2001). The sealing arrangements on pumps will contribute to the power absorbed. Often the use of gas barrier seals, balanced seals, and no- contacting labyrinth seals optimize pump efficiency.

xv Curtailing Leakage Through Clearance Reduction. Internal leakage losses are a result of differential pressure across the clearance between the impeller and the pump casing. The larger the clearance, the greater is the internal leakage causing inefficiencies. The normal clearance in new pumps ranges from 0.35 to 1.0 mm (Hydraulic Institute and Europump, 2001). With wider clearances, the leakage increases almost linearly with the clearance. For example, a clearance of 5 mm decreases the efficiency by 7 to 15% in closed impellers and by 10 to 22% in semi-open impellers.

xvi Dry Vacuum Pumps. Dry vacuum pumps were introduced in the semiconductor industry in Japan in the mid-1980s. The advantages of a dry vacuum pump are high energy efficiency, increased reliability, and reduced air and water pollution. It is expected that dry vacuum pumps will displace oil- sealed pumps (Ryans and Bays, 2001) in the next 5 to 7 years. Dry pumps have major advantages in applications where contamination is a concern.

4.5.16 Lighting

Lighting and other utilities represent less than 3% of electricity use in refineries. Still, potential energy efficiency improvement measures exist, and may contribute to an overall energy management strategy. Because of the relative minor importance of lighting and other utilities, this Energy Guide focuses on the most important measures that can be undertaken.

i Lighting Controls. Lights can be shut off during non-working hours by automatic controls, such as occupancy sensors. Manual controls can also be used in addition to automatic controls to save additional energy in small areas.

ii Replace T-12 Tubes by T-5 Tubes or Metal Halides. The initial output for T- 12 lights is high, but energy consumption is also high. T-12 tubes have poor efficacy, lamp life, lumen depreciation and color rendering index. Because of this, maintenance and energy costs are high. Replacing T-12 lamps with T-5 lamps approximately doubles the efficacy of the former. There are a number of

T-5 lights and ballasts in the market and the correct combination should be chosen for each system.

iii Replace Mercury Lights by Metal Halide or High-Pressure Sodium Lights. In industries where color rendition is critical, metal halide lamps save 50% energy compared to mercury or fluorescent lamps. Where color rendition is not critical, high-pressure sodium lamps offer energy savings of 50 to 60% compared to mercury lamps. High-pressure sodium and metal halide lamps also produce less heat, reducing HVAC loads. In addition to energy reductions, the metal halide lights provide better lighting, provide better distribution of light across work surfaces, improve color rendition, and reduce operating costs (GM, 2001).

iv Replace Standard Metal Halide HID With High-Intensity Fluorescent Lights. Advantages of the high efficiency fluorescent lamps are many: lower energy consumption, lower lumen depreciation over the lifetime of the lamp, better dimming options, faster start-up and restrike capability, better color rendition, higher pupil lumens ratings, and less glare (Martin et al., 2000). High-intensity fluorescent systems yield 50% electricity savings over standard metal halide HID.

v Replace Magnetic Ballasts With Electronic Ballasts. A ballast is a mechanism that regulates the amount of electricity required to start a lighting fixture and maintain a steady output of light. Electronic ballasts save 12 to 25% power over their magnetic predecessors (EPA, 2001). If automatic daylight sensing, occupancy sensing and manual dimming are included with the ballasts, savings can be greater than 65% (Turiel et al., 1995).

vi Reflectors. A reflector is a highly polished "mirror-like" component that directs light downward, reducing light loss within a fixture. Reflectors can minimize required wattage effectively.

vii Light Emitting Diodes (LEDs) or Radium Lights. One way to reduce energy costs is simply switching from incandescent lamps to LEDs or radium strips in exit sign lighting. LEDs use about 90% less energy than conventional exit signs (Anaheim Public Utilities, 2001).

Case study 31 : Using Energy Transformer for Plant Lighting

Brief

The actual wattage of lamps used is always higher than the manufacturer's rated wattage and it depends mainly on the characteristic of the Ballast with which the particular lamp is operated on the mains supply voltage at any given time. Thus saving can be achieved.

By using energy saving transformer for plant lighting in a refinery, 20% power consumption reduction has been possible in two major units, i.e. Crude Distillation unit and hydrocracker resulting in saving of 9 lakhs kwhr/year.

Energy Savings

Investment costs : Rs. 4.46 lakhs (for the transformer)Savings achieved : Rs. 27 Lakhs/annumPay back period : 2 months

199198

iii High Efficiency Belts (Cog Belts). Belts make up a variable, but significant portion of the fan system in many plants. It is estimated that about half of the fan systems use standard V- belts, and about two-thirds of these could be replaced by more efficient cog belts (Xenergy, 1998). Standard V-belts tend to stretch, slip, bend and compress, resulting in loss of efficiency. Replacing standard V-belts with cog belts can save energy, even as a retrofit. Cog belts run cooler, last longer, require less maintenance and have an efficiency that is about 2% higher than standard V-belts. Typical payback periods is less than one year.

4.5.18 Power Generation

Most refineries have some form of onsite power generation. In fact, refineries offer an excellent opportunity for energy efficient power generation in the form of combined heat and power production (CHP). CHP provides the opportunity to use internally generated fuels for power production, and allowing greater independence of grid operation. This increases reliability of supply as well as the cost-effectiveness.

i Combined Heat and Power Generation (CHP)

The petroleum refining industry is one of the largest users of cogeneration or CHP in the country. Total installed capacity is next only to the chemical and pulp & paper industry. Still, only about 10% of all steam used in refineries is generated in cogeneration units. Hence, the petroleum refining industry is also identified as one of the industries with the largest potential for increased application of CHP.

Wherever process heat, steam, or cooling and electricity are used, cogeneration plants are significantly more efficient than standard power plants because they take advantage of what are losses in conventional power plants by utilizing waste heat. In addition, transportation losses are minimized when CHP systems are located at or near the refinery.

Innovative gas turbine technologies can make CHP more attractive for sites with large variations in heat demand. Steam injected gas turbines (STIG or Cheng cycle) can absorb excess steam, e.g., due to seasonal reduced heating needs, to boost power production by injecting the steam in the turbine. The size of typical STIGs starts around 5 MWe, and is currently scaled up to sizes of 125 MW. STIGs have been installed at various sites worldwide, especially in Japan, Europe and in the United States. Energy savings and payback period will depend on the local circumstances (e.g., energy patterns, power sales, conditions).

Steam turbines are often used as part of the CHP system in a refinery or as stand-alone systems for power generation. The efficiency of the steam turbine is determined by the inlet steam pressure and temperature as well as the outlet pressure. Each turbine is designed for a certain steam inlet pressure and temperature. The operators should make sure that the steam inlet temperature and pressure are optimal. An 18°F decrease in steam inlet temperature will reduce the efficiency of the steam turbine by 1.1% (Patel and Nath, 2000). Similarly, maintaining exhaust vacuum of a condensing turbine or the outlet pressure of a backpressure turbine too high will result in efficiency losses.

Case study 32 : Replacement of conventional tube-lights with energy efficient tube-lights

Brief

During the course of the audit it was found that there are around 3500 nos. of conventional 40W fluorescent tube-lights installed in the plant and operating on the normal copper chokes. These type of fittings take more power as compared to the energy efficient tube-lights now available in the market. It is therefore recommended to replace all the existing conventional tube light fittings with the energy efficient tube-lights along-with electronic ballast. The cost benefit analysis of replacing the existing fluorescent tube-lights (FTLs) with T-5 is substantial.

Energy Savings

4.5.17 Fans

Fans are used in boilers, furnaces, cooling towers, and many other applications. As in other motor applications, considerable opportunities exist to upgrade the performance and improve the energy efficiency of fan systems. Efficiencies of fan systems vary considerably across impeller types (Xenergy,1998). However, the cost-effectiveness of energy efficiency opportunities depends strongly on the characteristics of the individual system.

i Fan Oversizing. Most of the fans are oversized for the particular application, which can result in efficiency losses. However, it may often be more cost- effective to control the speed, than to replace the fan system.

ii Adjustable Speed Drive (ASD). Significant energy savings can be achieved by installing adjustable speed drives on fans. Savings may vary between 14 and 49% when retrofitting fans with ASDs (Xnergy, 1998)

INSTALLATION OF T -5 FTLs WITH ELECTRONIC BALLAST IN PLACE

OF EXISTING CONVENTIONAL FTLs

Number of tube-lights 3500

Present power consumption per tube-light W 48

Total power consumption by these tube lights kW 168

Power consumption per tube light after

replacement with T-5 & electronic ballast W 28

New power consumption kW 98

Power saved kW 70

Annual operating time hrs 3300

Annual energy savings kWh 231000

Cost benefit Rs. Lacs 10.40

Expected Investment Rs. Lacs 19.25

Payback period months 22

201200

Case study 33 : Installation of lower capacity Pump in HRSG

Brief

3Installation of a smaller pump of rated capacity 37m /hr for feeding water to Heat Recovery Steam Generator (HRSG-5) and input power requirement of new 45 kw pump motor is available from the steam turbine (which will be able to produce max 150 kw). This could replace the existing pump/motor which consumes 146 kw for supplying the water to HRSG-4. The saving of 146 kw is achieved by installing a lower capacity pump. By this, the requirement of PRV is to reduce 6.5 TPH of MP steam to LP steam for process required.

Energy Savings

Investment costs : Rs. 22 lakhs Savings achieved : Rs. 8.6LakhsPay back period : 2.6 years

ii Steam Expansion Turbines

Steam is generated at high pressures, but often the pressure is reduced to allow the steam to be used by different processes. For example, steam is generated at 120 to 150 psig. This steam then flows through the distribution system within the plant. The pressure is reduced to as low as 10-15 psig for use in different process. Once the heat has been extracted, the condensate is often returned to the steam generating plant. Typically, the pressure reduction is accomplished through a pressure reduction valve (PRV). These valves do not recover the energy embodied in the pressure drop. This energy could be recovered by using a micro scale backpressure steam turbine. Several manufactures produce these turbine sets.

iii High-temperature CHP

Turbines can be pre-coupled to a crude distillation unit (or other continuously operated processes with an applicable temperature range). The off gases of the gas turbine can be used to supply the heat for the distillation furnace, if the outlet temperature of the turbine is high enough. One option is the so-called 'repowering' option. In this option, the furnace is not modified, but the combustion air fans in the furnace are replaced by a gas turbine. The exhaust gases still contain a considerable amount of oxygen, and can thus be used as combustion air for the furnaces. The gas turbine can deliver up to 20% of the furnace heat.

Another option, with a larger CHP potential and associated energy savings, is "high- temperature CHP". In this case, the flue gases of a CHP plant are used to heat the input of a furnace or to preheat the combustion air.

iv Gasification

Gasification provides the opportunity for cogeneration using the heavy bottom fraction and refinery residues (Marano, 2003). Because of the increased demand for lighter products and increased use of conversion processes, refineries will have to manage an increasing stream of heavy bottoms and residues. Gasification of the heavy fractions and coke to produce synthesis gas can help to efficiently remove these by-products. The state-of-the-art gasification processes combine the heavy by-products with oxygen at high temperature in an entrained bed gasifier.

Due to the limited oxygen supply, the heavy fractions are gasified to a mixture of carbon monoxide and hydrogen. Sulfur can easily be removed in the form of H S to 2

produce elemental sulfur. The synthesis gas can be used as feedstock for chemical processes. However, the most attractive application seems to be generation of power in an Integrated Gasifier Combined Cycle (IGCC). In this installation the synthesis gas is combusted in a gas turbine (with an adapted combustion chamber to handle the low to medium-BTU gas) generating electricity. The hot flue gases are used to generate steam. The steam can be used onsite or used in a steam turbine to produce additional electricity (i.e., the combined cycle). Cogeneration efficiencies can be up to 75% (LHV) and for power production alone the efficiency is estimated at 38-39% (Marano, 2003).

Entrained bed IGCC technology is basically developed for refinery applications, but is also used for the gasification of coal. Hence, the major gasification technology developers were oil companies like Shell and Texaco. IGCC provides a low-cost opportunity to reduce emissions (SOx, NOx) when compared to combustion of the residue, and to process the heavy bottoms and residues while producing power and/or feedstocks for the refinery.

IGCC is being used by the Shell refinery in Netherlands to treat residues from the hydrocracker and other residues to generate 110 MWe of power and 285 tonnes of hydrogen for the refinery. The investment costs will vary by capacity and products of the installation. The capital costs of a gasification unit consuming 2,000 tons per day of heavy residue would cost about $229 million of the production of hydrogen and $347 million for an IGCC unit. The operating cost savings will depend on the costs of power, natural gas, and the costs of heavy residue disposal or processing.

4.6 Refinery Environmental Issues

Refineries are industrial sites that manage huge amounts of raw materials and products and are intensive consumers of energy and water. In their storage and refining processes, refineries generate emissions to the atmosphere, to the water and to the soil, to the extent that environmental management has become a major factor for refineries. The type and quantity of refinery emissions to the environment are oxides of carbon, nitrogen and sulphur, particulates mainly generated from combustion processes, and volatile organic carbons. Water is used intensively in a refinery as process water and for cooling purposes. The main water contaminates are hydrocarbons, sulphides, ammonia and some metals.

In the context of the huge amount of raw material that are processed, refineries do not generate substantial quantities of waste. Currently, waste generated by refineries are dominated by sludges, and spent chemicals e.g. acids, amines, catalysts. Emissions to air are the main pollutants generated by the oil refineries. For every million ton of crude oil processed, refineries emit from 20000 - 820000 tonnes of carbon dioxide, 60-700 tonnes of nitrogen oxides, 10 - 3000 tonnes of particulate matter, 30 - 6000 tonnes of sulphur oxides and 50 - 6000 tonnes of volatile organic chemicals. To process per million tonnes of crude oil, refineries generated 0.1 to 5 Million of waste water and 10 - 2000 tonnes of solid waste. These big differences in emissions can be partially explained by the differences in integration and type of refineries e.g. simple vs. complex.

A large number of techniques have been considered in the determination of best available techniques to combat emissions in various refining processes.

203202

4.6.1 Crude Desalting

Increased efficiency of desalters may reduce wash water usage. Other environmental benefits would be limited to energy savings, related to more efficient electric field.

Available Techniques to Combat Emissions

(i) Enhance the oil/water separation before discharge to the waste water treatment plant

The system results in oil/ water separation, reducing the charge of oil to the waste water treatment and recycling it to the process as well as reductions in the oily sludge generation. With the application of the technique some to the API separators.

(ii) Enhance the solid/ water-oil separation

By using water at low pressure and loss shear mixing device, the content of oil in the generated sludges can be decreased and the separation of the sludges from the water phase can be enhanced. In a few refineries, desalters have been equipped with a bottom flushing system.

(iii) Re-use of water for the desalter

By reusing the water, the refinery could reduce the hydraulic loading to the waste water treatment units and reduce consumption of water.

(iv) Stripping of the desalter brine

Strip desalter brine for hydrocarbons, sour components and ammonia removal before sending treatment This can be resulted in reduction of the hydrocarbon, sulphur and ammonia content of the waste water generated within the desalter. For example, phenol emissions can be reduced by 90% and benzene emissions by 95%.

4.6.2 Distillation CDU/ VDU

Potential releases into the air from primary distillation units are: -

• Flue gases arising from the combustion of fuels in the furnaces to heat the crude oil.

• Pressure relief valves on column overheads; relief from overhead accumulator are piped to flare as well as the vent points.

• Poor containment in overhead systems, including barometric sumps and vents.

• Glands and seals on pumps, compressors and valves.• De-coking vents from process heaters. During furnace decoking, some

emission of soot can occur if operation is not properly controlled in terms of temperature or steam/ air injection.

• Venting during clean-out procedures.• Some light gases leaving the top of the condensers on the vacuum

distillation column. • Fugitive emissions from atmospheric and vacuum distillation units alone

account for 5-190 t/yr for a refinery with a crude capacity of around 8.5 MT/ yr.

The following table gives example of the air emissions generated by the atmospheric and vacuum distillation units by two European refineries. These tables include the emissions from combustion of fuels in the furnaces.

Table 4.19 Examples of air emissions generated by crude oil and vacuum distillation units

Process Waste Water

3Process waste water generated in the atmospheric distillation units is 0.08 - 0.75 m per tonne of crude oil processed. It contains oil, H S, suspended solids, chlorides, 2

mercaptans, phenol, an elevated pH, and ammonia and caustic soda used in column overhead corrosion protection. It is generated in the overhead condensers, in the fractionators and can also become contaminated from spillages and leaks. The overheads reflux drum (gasoil dryer condensator) generates 0.5% water on crude + 1.5% steam on feed with a composition of H S 10 - 200 mg/I and NH 10 - 30 mg/I. 2 3

Sour water is normally sent to water stripper/treatment.

Wastewater (sour water) is generated in the vacuum distillation units from process steam injection in furnace and vacuum tower. It contains H S, NH and dissolved 2 3

hydrocarbons. If steam ejectors and barometric condensers are used in vacuum 3distillation, significant amounts of oily wastewater can be generated (+10 m /h)

.containing also H S, NH2 3

Residual Wastes Generated

Sludges can be generated from the cleaning-out of the columns. The amount depends on the mode of desludging and the base solid and water content of the crude processed. The range of solid waste generation from a crude unit of 8.5 MT/ yr ranges from 6.3 - 20 t/day.

Available techniques to combat emissions

(i) Treatment of non-condensables from vacuum ejector set condensor uncondensable from overhead condensers can be passed to light ends treatment or recovery systems or refinery fuel gas systems; sour uncondensable gases vented from sealed barometric pumps of vacuum distillation units should be extracted and dealt with in a manner appropriate to the nature of the sour gas.

3Vacuum distillation column condensers may emit 0.14 kg/m of vacuum feed and can be reduced to negligible levels if they are vented to heater or incinerator. Pollution reduction is achieved if vacuum gaseous streams (vent gas) are routed to an appropriate amine scrubbing unit instead of being directly burned in the process heater.

Installation Fuel Consumption

(GWh/yr)

Throughput (MT/yr)

Units SO2 NOx CO CO2 Particu-lates

CDU mg/m3 35 100 100 5

1138.8 8.5 Crude Oil t/yr 35.2 100.4 100.4 220927 5

Vacuum

mg/m3

35

100

100

5

Distillation 639.54.5

Atm. Res. t/yr 19.8 56.6 56.6 182252 2.8

205204

(ii) Waste Water treatment and re-use

The overhead reflux drum generates some waste water. That water can be re-used as a desalter wash water. Sour water from atmospheric and vacuum unit condensates should pass to a sour water stripper in enclosed systems to optimize water re-use by application of side-stream softening to blowdown streams. This reduces water consumption and reabsorb pollutants.

(iii) Other techniques to consider in the atmospheric units are:-

a) De-coking vents to be provided with suitable knock-out and dust suppression facilities; suitable methods of preventing emissions during clean-out procedures need to be used.

b) Many oily sludges can be sent to the crude distillation or in alternative to the coking unit where they become part of the refinery products.

c) Use of spend caustic instead of fresh caustic for corrosion control on distillation unit.

4.6.3 Fluid Catalytic Cracking - FCC

This section gives emission information from the FCC when it is run under favourable conditions and the regenerator in total combustion mode. The catcracker is the source of SO and Nox, CO , CO, dust particulates, N O, SO , 2 2 2 3

metals, hydrocarbons (ex. Aldehydes) and ammonia emissions. For example, the basic design of a FCC includes two-stage cyclones in the regenerator vessel, which prevent the bulk of the fine catalyst used from escaping from the system. However, smaller catalyst particles, some of which are introduced with fresh catalyst and some created by attrition in the circulating system, are not easily retained by the two-stage cyclone system. Consequently, in many cases, other abatement techniques can be included to complement the process abatement techniques. The table gives a summary of the lowest emissions of pollutants to the atmosphere due to an uncontrolled catcracker.

Table 4.20 Emission factors in Kg. /1000 litres of fresh feedstock

Available Techniques to combat Emissions

(i) Partial combustion mode in the regenerator

The use of partial combustion mode together with a CO boiler generates less CO and Nox emissions compared with full combustion.

(ii) Hydrotreatment of feed to the catcracker

FCC feed hydrotreatment can reduce the sulphur content to <0.1 - 0.5% w/w (depending on the feedstock).

PM Sox

(as SO2) CO

HC

Nox (as No2)

Aldehydes

NH3

0.267 – 0.976

0.286 – 1.505

39.2 0.630 0.107 – 0.416 0.054 0.155

(iii) Selective non-catalytic reduction (SNCR)

These systems reduce the NOx emissions by 40-80%. The outlet 3concentrations can be down to <200 - 400 mg/Nm @3% O depending on the 2

nitrogen content of the feedstock. Instead of ammonia, urea can be also used. The use of urea has the advantage to be more soluble in water and consequently reduce the risk of handling/ storage of NH .3

(iv) Wet scrubbing

A suitably designed wet scrubbing process will normally provide an effective removal efficiency of both SO /SO and particulates. With the 2 3

inclusion of an extra treatment tower, to oxidize the NO to NO , NOx can 2

also be removed partially.

(v) Venturi Scrubbing

Venturi scrubbing can also remove most of the sulphur dioxide present in the flue gases. Tertiary cyclones with venturi scrubber in the FCCU regenerator have reached efficiencies of 93% in reducing SO and particulate emissions.2

4.6.4 Catalytic Reforming

Air emissions from catalytic reforming arise from the process heater gas, hydrocarbons from pressure relief valves and leakages and regeneration. Hydrocarbons and dust releases may arise from venting during catalyst replacement procedures and during clean-out operations. The table 4.21 shows an example of emissions to the air generated by reformers in two European refineries. The table also shows the emissions generated by the heaters.

Table 4.21

The amount of waste water generated in the catalytic reforming is around 1-3 litres per tonne of feestock. The waste water contains high-level of oils, suspended solids, COD and relatively low levels of H S (sulphides), chloride, ammonia and 2

mercaptans. Spent catalyst fines (alumina silicate and metals) may be generated from the particulate abatement techniques. Spent catalyst generated is around 20 to 25 tonnes per year for a 5 Mtonnes per year refinery.

Available Techniques to combat Emissions

(I) Type of catalyst promoter

Ozone depleting substances (e.g. carbon tetrachloride) are sometimes used during the regeneration of the catalyst of the reformer. Emissions of such

Installation Fuel Consumption

Throughput (t/yr)

SO2 NOx CO CO2 Particulars

Platformer Mider (1)

753.4

1000000 Naphtha

mg/m3

t/yr

kg/t feed

35

24.1

0.024

100

68.7

0.069

100

68.7

0.069

146152

146

53.40.003

Platformer OMV

494.1 728000 Naphtha

mg/m3

t/yr kg/t feed

18 8.8 0.012

170 83 0.114

5 2.4 0.003

95848 132

10.50.001

Notes: Data are related to yearly average, 3% O2, dry conditions. (1) Emissions from the Mider refinery, only

limit values are given. Loads and specific emissions were calculated.

207206

substances should be minimized by using less harmful substitutes or by using them in confined compartments.

(ii) Cleaning of the regeneration flue gas

Regenerator flue gas containing HCI, H S, small quantities of catalyst fines, 2

traces of Cl , SO and dioxides can be sent to a scrubber prior to release to 2 2

atmosphere. This results in reduction of particulates and volatile acids (HCI, H S). It has been reported that Cl filter also traps dioxins.2 2

(iii) Electrostatic precipitator in the regeneration flue gas

Regenerator flue gas containing HCI, H S, small quantities of catalyst fines, 2

traces of Cl , SO and dioxins can be sent to an electrostatic precipitator prior to 2 2

release to atmosphere. This results in reduction of particulate content in the flue gas coming from the regenerator.

(iv) Dioxins formation in catalytic reforming units

Dioxins are typically formed in the three types (continuous, cyclic and semi regenerative) of catalytic reforming during the regeneration of the catalyst. If the regenerator flue gas is treated in a water scrubber, dioxins are transferred in waste water. In some other cases, the use of fixed bed filters have resulted in combine reduction of chlorine and dioxins.

4.6.5 Hydrogen Consuming Processes (Hydrotreater/ Hydrocracker)

i Hydrotreating

Air emissions from hydrotreating may arise from process heater flue gas vents, fugitive emissions and catalyst regeneration (CO , CO, NOx, SOx). The off-2

gas stream may be very rich in hydrogen sulphide and light fuel gas. The fuel gas and hydrogen sulphide are typically sent to the sour gas treatment unit and sulphur recovery unit. Hydrocarbons and sulphur compounds from pressure relief valves; leakages from flanges, glands and seals on pumps, compressors and valves, particularly on sour gas and sour water lines; venting during catalyst regeneration and replacement procedures or during cleaning operations. The following table 4.22 shows two examples of emissions from hydrotreating processes. These air emissions include the emissions generated by the combustion of fuel required in those processes.

Table 4.22

Installation Mider

Fu

el

co

nsu

mp

tio

n(G

Wh

/yr)

Th

rou

gh

pu

t(t

/yr)

Un

its

SO

2

NO

x

CO

CO

2

Part

icu

lars

Naphtha

1500000

Hydrotreater 205.9

Naphtha

mg/m3

t/yr

kg/t feed

35

7.1

0.005

100

20.3

0014

100

20.3

0.014

3993727

510.001

Middle distillate 205.9

3000000 GO

51

mg/m3 t/yr kg/t feed

35 7.1 0.002

100 20.3 0.007

100 20.3 0.007

3993713

0Vacuum distillate 578.2

2600000

VGO

35

18.6

100

53.2

100

53.2

164776

52.7

mg/m3

t/yr

kg/t feed

0.007

0.02

0.02

63

0.001

Emissions are only limit values. Loads and specific emissions were calculated. Data are related to yearly average, 3% O2, dry conditions.

a Waste Water generated by hydrotreatments

Hydrotreating and hydroprocessing generate a flow of waste water of 30-55 l/tonne. It contains H S, NH , high pH, phenols, hydrocarbons, suspended 2 3

solids, BOD and COD. This process sour water should be sent to the sour water stripper/ treatment. Potential releases into water include HC and sulphur compounds from spillages and leaks, particularly from sour water lines. In distillate hydro treatments, solid deposits such as (NH ) SO and NH CL are 4 2 4 4

formed in the cooler parts of the unit and must be removed by water wash.

b Solid Wastes generated by hydrotreatments

Those processes generate spent catalyst fines (aluminium silicate and metals Co/Mo and Ni/ Mo 50 - 200 t/yr for 5 Mt/ yr refinery). For process units using expensive catalysts, contracts with the supplier exist for taking the spent catalyst back for regeneration and/ or recycling. This practice is also being adopted for other types of catalysts. During the last 20 years the use of catalytic processes has increased considerably and hence also the regeneration and rework services, particularly used to capture the water content of some streams (e.g. distillate hydrodesulphurisation).

ii Hydrocracking

Emissions from hydrocracking units included heater stack gas containing CO, SOx, NOx, hydrocarbons and particulates that generate smoke, grit and dust in the flue gas, fugitive emissions (hydrocarbons) and catalyst regeneration (CO , 2

CO, NOx, SOx, and catalyst dust). Fuel gas and bleed stream will contain H S 2

and should be further treated. VOCs are generated by the non-condensable from vacuum ejectors set condenser.

a Waste Water

Hydrocracking generates a flow of waste water of 50-110 I per tonne processed. It contains high COD, suspended solids, H S, NH and relatively 2 3

low levels of BOD. The sour water from the first stage HP separator, LP separator, and overhead accumulator should be sent to the sour water stripper/ treatment. Effluent from hydro conversion processes may contain occasionally metals (Ni/ V).

b Solid wastes

Hydrocracking also generates spent catalysts fines (metals from crude oil, and hydrocarbons). Catalyst should be replaced once per <1-3 years generating an average of 50-200 t/yr for a refinery of 5 Mt/ yr. Hydroconversion normally generates between 100 and 300 t/yr of spent catalysts which contain more heavy metals than hydrocracking catalysts.

4.6.6 Hydrogen Production

The feed for the hydrogen plant consists of hydrocarbons in the range from natural gas to heavy residue oils and coke. The conventional steam reformer process produces hydrogen of 97-98% v/v purity and is the most commonly used method for hydrogen production. The second commonly used route is to transform heavy oil residues to petroleum coke and its subsequent gasification

209208

to produce syn gas. Hydrogen production through steam reformer and coke gasification results in various types of air emissions and generation of solid waste in case of coke gasification process.

i Steam Reforming

Nox emissions are the most important to consider. Other emissions such as SOx or water emissions are minimal, because low-sulphur fuel is typically used and there are few emissions other than flue gas. The choice of heat recovery system can have a major effect on NOx production, since both the amount of fuel fired and the flame temperature will be affected. NOx emissions from a steam-reforming unit using gas or light gasoline as fuels and with low -

3NOx burners are 25-40 mg/MJ (100-140 mg/ Nm , 3% O ). Other emissions, 2

such as CO , originate from carbon in the feed.2

ii Coke gasification

Sulphur sorbents, such as limestone (CaCO ) or dolomite (Mg, Ca carbonate), 3

are normally used in the gasifier, reducing drastically the sulphur content. 3Sulphur composition in the exhaust gas ranges from 600 to 1200 mg/Nm of

H S and COS. If no sorbent is used, the sulphur content of the gas will be in 2

proportion to the sulphur in the feed. In oxygen-blown gasification, the sulphur 3content will be about 10000 mg/ Nm per percent sulphur in the feed.

Ammonia is formed in the gasifier from the fuel-bound nitrogen. Ammonia in the product gas typically contained less than 5% of the fuel-bound nitrogen when limestone was present in the gasifier.

iii Solid Waste

The solid waste from the process consists mainly of spent limestone and metals from the petcoke. Volatile metals and alkalis tend to accumulate on the particulate as the gas is cooled. The particulates contain a high percentage of carbon and are usually sent with the ash to a combustor, where the remaining carbon is burned and the calcium sulphide is oxidized to sulphate.

4.6.7 Alkylation

As described earlier, the alkylation process is catalyzed by using hydrofluoric acid or sulphuric acid. The main advantages of the HF alkylation process are the regeneration of HF which minimizes waste formation and disposal and also lower acid/ catalyst consumption as well as less consumption of energy and cooling. In the sulphuric acid alkylation process, the major drawback is the disposal of spent acid.

i HF- Alkylation Process

a Effluent gases

HF is a very dangerous compound because of its severe corrosive nature and burning effects of both liquid and fumes to skin, eyes and mucous membranes. Consequently, storage and handling it should comply with all safety rules. Scrubber using alkylation solution (NaOH or KOH) is necessary to remove HF from the incondensable gas stream. The acid relief neutralizer is operated so as to minimize the hydrogen fluoride content of the incondensable gas stream.

3Emissions levels of <1mg HF/Nm can be achieved. The vent gas should pass to flare not to the refinery fuel gas system; a dedicated flare /stack is normally retained for this. Fugitive emissions are also generated by this process. KF or NaF is formed during the neutralization process. The spent solution is stored and then requires regeneration with lime (or alumina).

b Water

HF alkylation effluents are a potential cause of acid excursions in refinery effluents and a high standard of control should be exercised on the neutralization treatment system, e.g. online pH monitoring. The effluent containing HF acid can be treated with lime (CaO-Ca (OH) , AlCl or CaCl or 2) 3 2

it can be neutralized indirectly in a KOH system to produce the desired CaF or 2

AlF (insolubles) which is separated in a settlement basin.3

c Wastes

The HF process also yields tars (polymeric material) but these are essentially free from HF. HF-containing tars are neutralized (with lime or alumina) and disposed of by incineration or blended as a fuel-oil component in small amounts because its pronounced odours. However, technology and special operating techniques such as internal acid regeneration have virtually eliminated this liquid-waste stream.

ii Sulphuric Acid - Alkylation Process

Technologies using sulphuric acid as catalyst produce very large quantities of spent acid (sulphuric and sulphonic acids) that has to be regenerated. The transport of spent and fresh acid to and from the sulphuric acid regeneration has give rise to some concern and increased the pressur on refiners to establish sulphuric acid regeneration plants near the alkylation unit. In some cases this transport to/from the regeneration facility is by pipeline. However, no major new improvements have been introduced in sulphuric acid alkylation technology dealing with the spent acid issue. Fugitive emissions from this process is similar to the HF alkylation.

Potential releases in terms of air pollutants, wastewater and solid waste generated by the alkylation processes are summarized in the tables 4.23, 4.24 & 4.25 given below:

Table 4.23: Air emissions generated by the alkylation processes

Air Pollutant Sulphuric acid HydrofluoricCO2, SO2, NOx and other pollutants arise from the furnaces*

From column heating furnaces

From column heating furnaces

Hydrocarbons May be released from pressure reliefs, storage, handling operations, spillages and fugitive emissions and water and waste discharges

May be released from pressure reliefs, storage, handling operations, spillages and fugitive emissions and water and waste discharges

Halogens n.a. Fluoride compounds may be released from pressure reliefs, vent gas and spillages

Odours n.a.

Acid-sulphide oil may be released from process shut-down ponds during maintenance work, particularly the descaling of pipes conveying hydrogen fluoride. This may be odorous

* Emissions from these combustion processes are addressed in an integrated way.

211210

Table 4.24: Waste water generated by alkylation processes

Table 4.25: Solid waste generated by the alkylation techniques

4.6.8 Coking Process

The most important health and safety aspect of coking processes is the handling of the coke fines.

i Emissions to the air

Air emissions from coking operations include the process heater flue gas emissions and fugitive emissions. In addition, the removal of coke from the drum (delayed coking) can release particulate and any remaining hydrocarbons to the atmosphere. The main pollutants generated as well as the sources are described below: -

• Hydrogen sulphide and sulphur compounds in mercaptans may be released from the sour water stream from reflux condensers.

• Hydrocarbons may be released from pressure reliefs on reflux drums and vessels, quench tower emissions, storage and handling operations, spillages and waste and water discharges.

• Particulate matter may be released from the kiln gas cleaning system, the rotary cooker gas cleaning system, coke handling and storage, loading operations and from the calcinatory process.

Water parameter Sulphuric Hydrofluoric

Waste Water

Waste water produced in the alkylation processes has low pH, suspended solids, dissolved solids, COD, H2S, and spend acid.

Hydrocarbons

n.a.

HC from separator drains (surge drum, accumulator, dryer) and spillages, and of acidic effluent containing dissolved and suspended chlorides and fluorides from the settlement pit or the process shutdown ponds.

Acid Sulphuric acid

Effluents from HF scrubber are 2- 38 m /h with compositions min/ max of 1000 – 10000 ppm F; after time treatment 10 – 40 ppm F.

Solid waste Sulphuric Hydrofluoric

Sludge n.a.

The flow 7 – 70 kg sludge per kg used HF (dry solids contents 3 – 30%)

Hydrocarbons

Sludge generated in the neutralization process contains hydrocarbons. Dissolved polymerization products are removed from the acid as a thick dark oil.

HC from spent molecular sieves, carbon packings and acid-soluble oil. Sludge generated in the neutralization process contains hydrocarbons. Dissolved polymerization products are removed from the acid as a thick dark oil.

Acid products in the sludge

Sludge generated in the neutralization process contains sulphuric acid.

Inorganic fluorides (Na/KF) and chlorides from treatment stages. Sludge generated in the neutralization process contains CaF2.

Halides n/a Composition of sludge is 10 –40 ppm F

- after lime treatment.

ii Waste Water

Waste water is generated from the coke removal, water bleed from coke handling, sour water from fractionator overhead, cooling operations and from the steam injection and should be treated. The amount of waste water generated in the coking processes is around 25 litres per tonne of feedstock. It contains H S, NH suspended solids (coke fines with high metal contents), 2 3

COD, high pH, particulate matter, particulate matter, hydrocarbons, sulphur compounds, cyanides and phenols.

iii Solid Wastes

Solid wastes generated in the coking processes are coke dust (carbon particles and hydrocarbons) and hot oil blowdown sludges containing hydrocarbons.

iv Delayed Coking

1. Uncondensable vapours generated in the coking processes should not pass to the flare system.

2. Pressure reliefs from the coke drums should pass to the quench tower.3. Steam generated in this process can be used to heat up other refinery processes.4. The delayed coking process has a low level of heat integration. The heat to

maintain the coke drums at coking temperature is supplied by heating the feed and the recycle stream in a furnace. The atmospheric residue and/ or vacuum residue can be fed straight into the delayed coking unit without intermediate cooling, which results in a high heat integration level between the different units and saves a considerable amount of capital on heat exchangers.

v Fluid Coking

Another technique that can be used to prevent emissions or increase energy integration in the fluid coking is to use the coking gas in a gas turbine of a combined cycle unit. Extra information on the application of refinery fuel gas in combined cycle units appears in Table 4.26 .

Table - 4.26

Available techniques to combat emissions: -

I Handling and storage of the coke

• Cut the coke into a double roll cluster and convey it to an intermediate storage silo.

• Spray the coke with a very fine layer of oil, which sticks the dust fines to the coke.

• Covered and de-pressurized conveyor belts.• Aspiration systems to extract or collect dust.• Use of an enclosed hot blowdown system.• Dust extraction systems can be incorporated with loading equipment.

Process PM SOx (as SO2)

CO HC NOx (as NO2)

Aldehyde NH3

Fluid coking units uncontrolled

1.5

n.a.

n.a.

n.a.

n.a. n.a.

n.a.

Fluid coking with ESP and CO boiler

0.0196

n.a. Neg Neg n.a. Neg Neg

Neg: Negligible

213212

ii Particulate abatement in coking processes

The particulate abatement technique used in the FCC (Cyclones or ESP) that may be also used here, bag filters can be used in this processes.

SO abatement techniques2

Sulphur oxides are emitted during the coking processes, especially during the calcinations processes. The principal option to reduce sulphur dioxide releases from the process is the use of the lowest possible sulphur-content feedstocks. In practice, low-sulphur feeds are typically used for product quality reasons, since a substantial part of the sulphur remains fixed in the product.

iii Treatment of the waste water

In the coking processes, sour water is generated (steam condensate). Consequently, all water from the coking process is send to the sour-water stripper before being sent to the waste water treatment plant.

iv Separation of the oil/ coke fines from the coke-cutting water

The proposed pollution prevention alternative was to retrofit the sump where the oil/ coke fines are collected with an inclined plate separator to increase the separation efficiency.

Coke fines and water generated from the coke-cutting operation enter an in-ground sump where the solids and water are separated by gravity. A refinery study indicated that over twenty-five tones a year of coke fines entered the sewer system from that separator.

v Control and re-use of the coke fines

Coke fines are often present around the coker unit and coke storage areas. The coke fines can be collected and recycled before being washed to the sewers or migrating off-site via the wind. Collection techniques include dry sweeping the coke fines and sending the solids to be recycled or disposed of as non-hazardous waste. Another collection technique involves the use of vacuum ducts in dusty areas and vacuum hoses for manual collection which run to a small baghouse for collection. This results in reduced soil contamination by coke particulates including metals.

References :

1. Teri Energy Data Directory & yearbook 2007, TERI Press, New Delhi2. World Energy Outlook, 2007, IEA Publication, Paris, France3. World Oil Outlook 2007, OPEC Publication, Vienna, Austria4. Energy Efficiency Improvement and Cost Saving opportunities for Petroleum

Refineries, Ernest Worrell and Christina Galitsky, Energy Analysis Department, Ernest Orlando Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720 February, 2005

5. Integrated Pollution Prevention & Control Reference Document on Best Available Techniques for mineral oil & Refineries, European Union, February, 2003.

6. Sectoral Trends in Global Energy use & GHG Emissions, Environmental Energy Technologies Divn. LBNL publication, July 2008, California Berkerley CA 94720 (USA)

7. Annual Report 2007-08, Ministry of Petroleum and Natural Gas, GOI8. BP Statistical Review of World Energy, June, 2008, London UK9. Basic Statistics on Indian Petroleum & Natural Gas 2006-07, Ministry of

Petroleum & Natural Gas, GOI10. India in Figures, 2007 Ministry of Statistics & Programme Implementation,

GOI11. PPAC Ready Reckoner, Information as on 1.4.2008, PPAC, MOP&NG , New

Delhi12. Report of the Working Group on Petroleum & Natural Gas Sector for the XI

Plan (2007-2012), MOP&NG, GOI13. Worrel, E. and Galitsky, C. 2004, Profile of the Petroleum Refining Industry in

California. Berkley, CA: Lawrence Berkley National Laboratory. LBNL-55450

14. Zagoria, A. and R. Huycke, 2003. Refinery Hydrogen Management - The Big Picture. Hydrocarbon Processing 2 82 pp.41-46 (February, 2003)

15. California Energy Commission (CEC) and the Office of Industrial Technologies (OIT), US Department of Energy, 2002. Case Study : Pump System Retrofit Results in Energy Savings for a Refinery, August, 2001.

16. Van de Ruit, H. 2000. Improve Condensate Recovery Systems. Hydrocarbon Processing 12 79 pp.47-53 (December, 2000)

17. Hydrogen Processing (HCP) 2001. Advanced Control and Information Systems 2001. Hydrogen Processing 9 80 pp.73-159 (September, 2001)

18. Hodgson, J. and T. Walters. 2002 Optimizing Pumping systems to Minimize First or Life Cycle Costs. Proc. 19th International Pump Users Symposium, Houston, TX, February 25-28th, 2002.

19. Copper Development Association (CDA). 2001. High-Efficiency Copper Wound Motors Mean Energy. http://energy.copper.org/motorad.html.

20. Canadian Industry Program for Energy Conservation (CIPEC), 2001. Boilers and Heaters, Improving Energy Efficiency. Natural Resources Canada, Office of Energy Efficiency, Ottawa, Ontario, Canada.

21. Fisher, PW and D. Brennan. 2002. Minimise Flaring with Flare Gas Recovery Hydrocarbon Processing 6 81 pp.83-85 (June, 2002)

22. Hydraulic Institute and Europump. 2001. Pump Life Cycle Costs: A Guide to LCC Analysis for Pumping Systems. Parsippany, NJ

23. Dunn, R.F. and G.E. Bush. 2001. Using Process Integration Technology for CLEANER production. Journal of Cleaner Production 1 9 pp.1-23.

215214

41. Integrated Pollution and Prevention Control. 2002. Reference Document on Best Available Techniques for Mineral Oil and Gas Refineries. Joint Research Centre, European Commission, Seville, Spain.

42. Venkatesan, VV and N. Iordanova. 2003. A Case Study of Steam Evaluation in a Petroleum Refinery Proc. 25th Industrial Energy Technology Conference, Houston, TX , May 13-16, 2003.

24. Energy Information Administration (EIA), 2002. Petroleum Supply Annual 2001, Energy Information Administration, US Department of Energy, Washington, DC, June, 2002

25. Hydrocarbon Processing (HCP) 2001. Advanced Control and Information Systems 2001. Hydrocarbon Processing 9 80 pp.73-159 (September, 2001).

26. Integrated Pollution and Prevention Control. 2002. Reference Document on Best Available Techniques for Mineral Oil and Gas Refineries. Joint Research Centre, European Commission, Seville, Spain.

27. Ezersky, A., 2002. Technical Assessment Document: Further Study Measures 8 Flares (draft). Bay Area Air Quality Management District, San Francisco, CA

28. Golden, S.W. and S. Fulton. 2000. Low-cost Methods to Improve FCCU Energy Efficiency. Petroleum Technical Quarterly, Summer 2000, pp.95-103.

29. Hallale, N., 2001. Burning Bright : Trends in Process Integration. Chemical Engineering Progress 7 97 pp.30-41 (July, 2001)

30. Hydrocarbon Processing (HCP) 2000. Refining Processes 2000. Hydrocarbon Processing 11 79 pp.87-142 (November, 2000)

31. Parekh, P. (2000) Investment Grade Compressed Air System Audit, Analysis and Upgrade. In: Twenty-second National Industrial Energy Technology Conference Proceedings. Houston, Texas. April, 5-6: 270-279.

32. House, M.B., S.B. Lee, H. Weinstein and G. Flickinger.2002. consider Online Predictive Technology to reduce Electric Motor Maintenance Costs. Hydrocarbon Processing 7 81 pp.49-50 (July, 2002)

33. Panchal, CB and E-P. Huangfu, 2000. Effects of Mitigating Fouling on the Energy Efficiency of Crude Oil Distillation. Heat Transfer Engineering 21 pp. 3-9

34. Ingersoll Rand. 2001. Air Solutions Group-Compressed Air Systems Energy Reduction Basics. http://www.air.ingersoll-rand.com/NEW/pedward.htm. June, 2001.

35. Khorram, M. and T. Swaty.2002. US Refiners need more Hydrogen to Satisfy Future Gasoline and Diesel Specifications. Oil & Gas Journal, November 25th, 2002, pp.42-47.

36. Linnhoff March. 2000. The Methodology and Benefits of Total Site Pinch Analysis. Linnhoff March Energy Services. http://www.linnhoffmarch.com.com/resources/technical.html

37. Onsite Sycom Energy Corp. 2000. The Market and Technical Potential for Combined Heat and Power in the Industrial Sector. Energy Information Administration, US Department of Energy, Washington, DC.

38. Polley, G.T., S.J. Pugh and D.C. King. 2002. Emerging heat Exchanger Technologies for the Mitigation of Fouling in Crude Oil Preheat Trains. Proc. 24th Industrial Energy Technology Conference, Houston, TX, April 16-19, 2002.

39. Querzoli, A.L. AFA Hoadley and TES Dyron. 2002. Identification of Heat Integration Retrofit Opportunities for Crude Distillation and Residue Cracking Units. Proceedings of the 9th APCChE Congress and CHEMECA 2002, 29 September - 3 October 2002, Christchurch, NZ.

40. Radgen, P. and E. Blaustein (eds.), 2001. compressed Air Systems in the European Union, Energy, Emissions, Savings Potential and Policy Actions. Fraunhofer Institute, Karlsruhe, Germany.

217

Notes Chapter - 5

Exploration and Production

5.1 Introduction

India's GDP is growing at about 8-9% annually. Current projections are that this trend will continue. High growth rate demands enhanced energy inputs, particularly for a country like India where the per capita oil and gas consumption is almost one-fifth of the global average. At the present rate of consumption, it is expected that India's crude oil reserves will exhaust in less than 20 years from now while its natural gas reserves will last for about 40 years. An additional strain is placed by the fluctuating price of crude. Currently, we import over 73% of our crude oil requirements.

5.1.1 Sedimentary Basins of India

India has 26 sedimentary basins of which only about 20% are moderately to well explored. The remaining sedimentary area remains to be intensively explored. Judging by the spate of recent discoveries, the areas that are yet to be explored hold enormous promise.

Table - 5.1: Total Sedimentary Area: 3.14 Million Sq.Km.

Source : DGH

5.1.2 Production

Total oil production during 2007-08 was 34.11 MMT and that of gas 32.402 BCM. The contribution of Pvt/JV companies was about 18% of the total Oil & Gas production.

5.1.3 Drilling

Of the total of 415 wells drilled, 163 were exploratory and 252 were development wells. As in the previous year, the national oil companies contributed to the bulk of the drilling. A total of 1005050 meters were drilled which include 406960 meters of exploratory and 598090 meters of development drilling.

5.2 Energy Efficiency Improvement Scope In Upstream Sector

The upstream hydrocarbon sector can generally be divided into four distinct divisions:

1. Seismic survey, Exploration & development of hydrocarbon reservoirswhich primarily comprise of drilling rigs and allied equipment

Area (Million Sq.Km.)

Level of Exploration

1995-96

1998-99

2004-05

2006-07

Unexplored 1.557 1.276 0.698 0.468Exploration Initiated 0.556 0.837 1.155 1.376Poorly explored 0.529 0.529 0.689 0.655Moderate to well explored

0.498 0.498 0.598 0.641

219218

Each of these techniques has been hampered by its relatively high cost and in some cases, by the unpredictability of its effectiveness.

5.2.2 CO Injection 2

The EOR technique that is attracting the most new market interest is carbon dioxide (CO )-EOR. First tried in 1972 in Scurry County, Texas, CO injection has been 2 2

used successfully at number of locations today.

The presence of an oil bearing transition zone beneath the traditionally defined base (oil-water contact) of an oil reservoir is well established. What is now clear is that, under certain geologic and hydrodynamic conditions, an additional residual oil zone (ROZ) exists below this transition zone and this resource could add further to oil resource in place and could be recoverable with state-of-the-art CO -EOR 2

technologies.

Until recently, most of the CO used for EOR has come from naturally occurring 2

reservoirs. But new technologies are being developed to produce CO from 2

industrial applications such as natural gas processing, fertilizer, ethanol, and hydrogen plants in locations where naturally occurring reservoirs are not available. One demonstration at the Dakota Gasification Company's plant in Beulah, North Dakota is producing CO and delivering it by a new 204-mile pipeline to the 2

Weyburn oil field in Saskatchewan, Canada. Encana, the field's operator, is injecting the CO to extend the field's productive life, hoping to add another 25 2

years and as much as 130 million barrels of oil that might otherwise have been abandoned.

A turning point in CO -EOR advances is a project funded by US DOE in the Hall-2

Gurney field in Kansas that seeks to demonstrate this technology's time has come - providing energy, economic and environmental benefits. A companion project underway in the Hall-Gurney field involves testing the feasibility of 4-D high resolution seismic monitoring of CO injection in thin, relatively shallow mature 2

carbonate reservoirs. Incorporating such time-lapsed monitoring data into CO -2

EOR programs could dramatically improve the efficiency and economics of using the technology in many Mid-continent fields.

Additional work has examined potential improvements in CO -EOR technologies 2

beyond the state-of-the-art that can further increase this potential. This work evaluating the potential of "game changing" improvements in oil recovery efficiency for CO -EOR illustrates that the wide-scale implementation of next 2

generation CO -EOR technology advances have the potential to increase oil 2

recovery efficiency from about one-third to over 60 percent.

5.2.3 Other Areas

Crude Oil exploration is the most energy intensive operation and is explained in detail in this chapter. The other major areas where energy is consumed and opportunities for conservation exists are listed below:

5.2.3.1 Pumping Stations

The major energy consuming equipments generally are:

2. Production of Oil & Gas which may comprise of

a. Oil collection stationsb. Gas Compressor stationc. Sucker Rod Pumpsd. Water supply stationse. Power Station

3. Transportation of Oil & Gas which may comprise of

a. Crude Oil Pumping Stationsb. Gas Compressor Stations

4. Gas Based Petrochemical Complexes

a. Petrochemical Plantb. LPG Recovery Plantsc. LPG Bottling Plants

Effective and result oriented conservation methods adopted by the upstream undertakings include reduction of gas flaring by re-injection of gas to underground reservoir, installation of waste heat recovery systems, utilization of non-conventional energy sources, undertaking energy audits & efficiency up gradation of equipment & appliances, substitution of diesel with natural gas, deployment of solar-powered illumination panels, battery operated vehicles, bio-gas etc.

5.2.1 Enhanced Oil Recovery

Crude oil development and production in oil reservoirs can include up to three distinct phases: primary, secondary and tertiary (or enhanced) recovery. During primary recovery, the natural pressure of the reservoir or gravity, drive oil into the wellbore combined with artificial lift techniques (such as pumps), which bring the oil to the surface. But only about 10 percent of a reservoir's original oil in place is typically produced during primary recovery. Secondary recovery techniques to the field's productive life generally by injecting water or gas to displace oil and drive it to a production wellbore, resulting in the recovery of 20 to 40 percent of the original oil in place. However, with much of the easy-to-produce oil already recovered from oil fields, producers have attempted several tertiary, or Enhanced Oil Recovery (EOR), techniques that offer prospects for ultimately producing 30 to 60 percent or more of the reservoir's original oil in place. Three major categories of EOR have been found to be commercially successful to varying degrees:

• Thermal recovery, which involves the introduction of heat such as theinjection of steam to lower the viscosity or thin the heavy viscous oil andimprove its ability to flow through the reservoir.

• Gas injection, which uses gases such as natural gas, nitrogen, or carbondioxide that expand in a reservoir to push additional oil to a productionwellbore or other gases that dissolve in the oil to lower its viscosity andimproves its flow rate.

• Chemical injection, which can involve the use of long-chained moleculescalled polymers to increase the effectiveness of waterfloods or the use ofdetergent-like surfactants to help lower the surface tension that oftenprevents oil droplets from moving through a reservoir.

221220

Consumption vs. Power Generated and by improving performance with reduced specific electrical energy consumption.

The major equipments are electrical system network, motors, air compressors, Cooling Towers, Illumination systems, where energy conservation opportunities can be explored.

Electrical System Network: Improvement opportunity can be explored by study of all the Transformer operations of various Ratings / Capacities, their Operational Pattern, Loading, No Load Losses, Power Factor Measurement on the Main Power Distribution Boards and possible improvements in energy metering systems for better control and monitoring.

5.2.3.5 Sucker Rod Pumps

The major equipments are motors, DG Sets, Illumination systems, etc.

5.2.3.6 Gas Processing Plants

The major equipments consists of motors, pumps, steam systems, HRSGs, Boilers, Captive Power houses, Gas Turbines, Steam turbines, Gas Compressors, Air Compressors, Steam Traps, Illumination, Heaters, distillation/ separation columns, cooling towers, transformers, electrical system networks, air conditioning etc.

Case Study 1: Energy Audit of a major Gas based Petrochemical Complex

Brief

The Petrochemical Complex is designed to process 12 million metric standard cubic meter per day (MMSCMD) of natural gas to produce 440,000 TPA of Ethylene in the first phase and down stream products, such as the various grades of high density polyethylene (HDPE) and linear low density polyethylene (LLDPE). A LPG recovery unit is being installed and successfully producing 258250 TPA of LPG and 71,000 TPA of Propane from the natural gas.

The main energy sources of the plant are electricity and Natural gas. The plant consumes about 42 Million kWh electrical units per annum (from the grid), around

3240 Million from in-house and natural gas quantity of 363 Million sm per annum.

Energy savings

Summary of Energy Savings

6* MMSCM = 10 Standard Cubic Metre

Annual savings : Rs. 246.3 Million Investment required : Rs. 124.7 MillionPayback period : 6 months

Thermal Energy Systems

The Plant has three utility boilers UB#1, UB#2 & UB#3, each designed to generate 2 oVHP steam at 105 kg/cm and 515 C. The VHP steam generated in the utility boilers

Description Unit Quantity Electricity @ Rs. 4.5/kWh

Million kWh/annum

25.8 Lean Gas @ Rs. 10/SCM MMSCM*/annum 13.0

Electrical Motors: Improvement opportunity can be explored in appropriate Loading Pattern, Power Factor improvement, Mechanical Power Transmission Systems and other operational parameters.

Pumping System: Improvement opportunity can be explored by optimising the pumping and allied system pressures, RPM of the engines, engine efficiencies and other operational parameters for crude oil driven engines for pumping of crude oil or product and fire fighting pumps (Engine or Motor Driven) and feasibility of reduction in the Power Consumption.

Air Compressors: Improvement opportunity can be explored by analysis of various parameters like intake receiver capacity, operational Free Air Delivery (FAD) of the Air Compressors, leakages in the system, evaluation of the feasibility of Pressure Optimisation etc.

Illumination System: Improvement opportunity can be explored by use of energy efficient lighting systems.

DG Sets Performance: Improvement opportunity can be explored by operation of DG Sets to evaluate their average cost of Power Generation and subsequently identify areas wherein energy savings could be achieved after analysing the operational practices.

Specific Energy Consumption: SEC per throughput of each station and comparison of SEC of each station should be found out and benchmarked.

Diesel & Crude Oil Handling System: Improvement opportunity can be explored by monitoring energy consumption in heater in centrifuge unit, fuel forwarding modules, etc. and study the feasibility of energy conservation.

5.2.3.2 Gas Compressor Stations (GCS)

Study of Gas Compressors in GCS (Motor / Gas Engine Driven Unit): Improvement opportunity can be explored by Studying the Operational practices being adopted, Monitoring the Specific Energy Consumption, Scheduling of the Gas / Motor Driven Compressors, Formulation of specific recommendations for reduction in the overall Electrical energy/Gas Consumption. The major equipments are Motors, Air Compressors, Cooling Towers, Illumination systems.

Cooling Towers: Improvement opportunity can be explored by studying the operational performance of the Cooling towers through measurements of temperature differential, air/ water flow rate and then evaluate specific performance parameters like approach, efficiency etc.

5.2.3.3 Water Supply Station

The major equipments are motors, pumps and Illumination systems

5.2.3.4 Power Station

Improvement opportunity can be explored by evaluating the operational efficiency of turbines & alternators, Evaluation of the Specific Energy Consumption pattern of the Gas/Steam Turbine as well as allied equipment, Load rationalization & overall reduction in the Specific Energy Consumption, Evaluation of Specific Gas/Steam

Annual savings : Rs. 3.7 Million Investment required : Rs. 3.5 MillionPayback period : 11 months

• Boiler feed water pump (Utility boiler#2)

The feed water pump operating efficiency was much below (38%) the desired pump efficiency level (60%) for efficient operation. By replacing the existing pump with an energy efficient pump, a saving of 0.42 Million kWh per year can be achieved.

Annual savings : Rs. 1.9 Million Investment required : Rs. 5.0 MillionPayback period : 32 months

• Utility Steam Turbines

The plant has installed two nos. of Steam Turbo Generators (STG#1 & STG#2); one is extraction type having a capacity of 15.5 MW and the other is condensing type of 25.5 MW, to meet the plant's electricity requirements.

STG# 1

• The observations and measurements showed that, the specific steam consumption per MW power generation is higher than the rated/design condition. This may be due to leakage in labyrinth-gland packing between two stages or any other maintenance reason like corrosion/erosion in turbine blade surface. Hence it was recommended to consult the manufacturer to ascertain the possible reasons. After rectifying the same the steam consumption may be reduced nearer to the designed requirement. The steam consumption (T/MW) in the HP and LP side is 21.23 and 12.21.

• The measurements and analysis showed that Steam Turbine efficiency inboth H.P. & L.P. stage was lower i.e. 61.8 % and 61.5 % than expected.

• The loading of the turbine was 59%.

• By enhancing the loading of the turbine, reducing the leakages, the operating efficiency of the turbine can be enhanced to 65% with an annual savings of 1.2 MMSCM per year.

Annual savings : Rs. 11.9 Million Investment required : Rs. 5.0 MillionPayback period : 5 months

STG#2

• The turbine was running at low operating efficiency of 57.8 % because ofoperation of turbine at part load of 59 %.

• By enhancing the loading of the turbine, reducing the leakages, the operating efficiency of the turbine can be enhanced to 65 % with an annual saving of 0.3 MMSCM per year

is used in utility steam turbines for power generation and subsequently for driving the boiler auxiliaries and for process heat applications. The recommendations pertaining to the operation of the two boilers (UB#1 & UB#3), which were in operation during the field visit of the audit are as follows:

• Optimization of excess air in Utility Boiler UB#2

The boiler was operating at a high excess air level of 68%, whereas the recommended level is 10%, resulting in high flue gas losses. As a result, the boiler efficiency dropped by 4 percent points to 91% (NCV basis) as against the design value of 95%. By maintaining the O % in flue gases always below 3% 2

(in order to keep excess air level below 15%) by continuous monitoring of O % 2

in flue gases and thereby regulating the combustion airflow to the boiler, a saving of 1 MMSCM of gas per year can be achieved.

Annual savings : Rs. 10.0 Million Investment required : Rs. 5.0 MillionPayback period : 6 months

• Optimization of excess air in Utility Boiler UB#3

The boiler was operating at a high excess air level of 46%, whereas the recommended level is 10%, resulting in high flue gas losses. As a result, the boiler efficiency dropped by 6 percent points to 80% (GCV basis) as against the design value of 86%. By maintaining the O % in flue gases always below 3% 2

(in order to keep excess air level below 15%) by continuous monitoring of O % 2

in flue gases and thereby regulating the combustion airflow to the boiler, a saving of 0.9 MMSCM of gas per year can be achieved.

Annual savings : Rs. 9.1 Million Investment required : Rs. 5.0 MillionPayback period : 6 months

• Replacement of inefficient UB#2 FD Fan with that of energy efficient fan

It was found that the efficiency of the steam turbine driven UB#2 FD fan was much below (23%) the desirable efficiency level (60%). Hence, by replacing the existing FD Fan of UB#2 with an energy efficient fan, a savingof 0.3 Million kWh per year can be achieved.

Annual savings : Rs. 1.4 Million Investment required : Rs. 3.5 MillionPayback period : 29 months

• Replacement of inefficient UB#3 FD Fan with that of energy efficientfan

The operational efficiency of UB#3 FD fan was poor (13%) compared to the desirable efficiency level (60%). Hence, by replacing the existing FD Fan with an energy efficient FD Fan, a saving of 0.82 Million kWh per year can be achieved.

223222

225224

Payback period : 3 months

• Maintenance of faulty steam traps

By repairing the traps which are chocked and let the condensate flow smoothly out of the system to ensure effective heat transfer, a saving of 0.1 MMSCM of natural gas per year can be achieved.

Annual savings : Rs. 1.0 Million Investment required : Rs. 1.0 Million approxPayback period : 12 months

• Performance evaluation of all steam traps

The savings estimated above was based on the survey conducted on 170 traps, which form less than 20% of the total traps installed in the plant. The actual energy savings that can be achieved by steam traps maintenance would be several times higher than what has been estimated above. Therefore, it was recommended to get a survey done for all the steam traps in the plant and replace / repair the faulty traps immediately to arrest energy losses in the steam system.

• Steam Distribution System

- Condensate recovery

A total of 7 TPH of condensate can be recovered and reused as boiler feed water from HDPE and LPG Plants. The investment required would be in terms of additional condensate pipes, condensate pump, and insulation of the network. In addition to the fuel savings, the other benefits would be reduced costs of water treatment of 7 TPH water. The net savings would be the 0.6 MMSCM of natural gas per year.

Annual savings : Rs. 6.2 Million Investment required : Rs. 3.0 MillionPayback period : 6 months

- Arresting steam leakages

The plant had steam leakages at a number of areas. By arresting the steam leakages from the identified areas (by replacing the damaged valves, pipefittings, flanges, traps, etc), a saving of 0.09 MMSCM of natural gas per year can be achieved.

Annual savings : Rs. 0.9 Million Investment required : Rs. 0.5 MillionPayback period : 7 months

- Improve insulation of pipes

A number of areas in the steam lines had high surface temperatures. The high surface temperatures of insulated steam headers / pipes indicate the damaged or inadequate insulation. It was recommended to replace the insulation to arrest the heat losses thereby saving 0.04 MMSCM of natural gas per year.

Annual savings : Rs. 3.3 Million Investment required : Rs. 2.5 MillionPayback period : 9 months

• Heat Recovery Steam Generators

By improving the efficiency of HRSG - I & II by de-scaling the water side surface, changing the layout of different components of the HRSG from the existing to the proposed i.e. in the sequence of Super Heater-II, Super Heater-I, Evaporator-II, Evaporator-I & Economizer, a saving of around 2% on a very conservative estimate can be achieved. The modifications will lead to increased steam generation. This increase will reduce the load on utility boilers, which will ultimately reduce the natural gas consumption by 1.8 MMSCM of natural gas per year.

Annual savings : Rs. 17.8 Million Investment required : Rs. 2.0 MillionPayback period : 2 months

• Cracked Gas (CG) Compressor

The specific steam consumption per KW shaft power in H.P. Stage was higher with respect to the rated designed condition because of low efficiency of steam turbine. By increasing the efficiency of HP as well as LP steam turbine a saving of 1 MMSCM fo natural gas can be achieved.

Annual savings : Rs. 10.2 Million Investment required : Rs. 3.0 MillionPayback period : 4 months

• Condensing Steam Turbine of Propylene (C R )Refrigeration Compressor3

The condensing steam turbine of C R compressor was running at poor 3

efficiency. This was due to leakage in labyrinth-gland packing between two stages or any other maintenance reason like corrosion/erosion in turbine blade surface. Hence it was recommended to consult the manufacturer to ascertain the possible reasons. After rectifying the same, a saving of 0.17 MMSCM of natural gas per year can be achieved.

Annual savings : Rs. 1.7 Million Investment required : Not ascertainedPayback period : NA

• Replacement of damaged traps

The plant had 44 faulty steam traps. By immediate replacement of these traps to arrest steam leakage and losses, a saving of 0.2 MMSCM of natural gas per year can be achieved.

Annual savings : Rs. 2.1 Million Investment required : Rs. 0.45 Million

227226

becomes imperative for the plant to keep a good power factor on the mainincomer. For this, the plant has installed capacitors. The average PF beingmaintained was very close to unity, which is a good practice.

• Motor Load Study:

A complete motor load survey was carried out during the energy audit so as to assess the motor loading pattern and assess the potential for motor down-sizing, application of VFD, soft starter etc. In all about 170 motors above 25kW were studied and the basis for categorising the motors as under-loaded was loading less than 50%. In all 44 motors were found to be under-loaded (26% of the motors studied). For the motors loaded less than 50%, an exercise was done to analyze the feasibility of replacement of these motors by suitably sized energy efficient motors (EEM). Few motors where the payback was less than 5 years are being recommended for such replacement. For motors that offer a payback of 5 years or less, the reduction in motor losses will be to the tune of 38.5 kW. An annual saving of 0.31 Million kWh per year can be achieved by replacing the under loaded motors.

Annual savings : Rs. 1.4 Million Investment required : Rs. 0.5 MillionPayback period : 5 months

• Power Factor Study:

During the audit of the electrical motors, the PF profiling was also done. For most of the motors it was found that the PF was quite healthy but for a few motors (20 in number out of a total of 170 studied), the PF was below 0.7, which may be due to the low loading at the point of measurements. It was advised that, for all motors, the PF should be kept as high as possible (ideally 0.95) so as to have reduced line losses, to ensure better voltage regulation at the motor end & healthy motor load performance, to take proper care regarding the loading pattern, over-hauling and re-winding practices.

• Compressors:

• It was recommended to operate 3 HT compressors in place of operating 2 LP air and 2 nitrogen compressors. The maximum air requirement for the plant

2is around 18400 CFM at a pressure of around 8 kg/cm . Since three HT compressors alone can meet this requirement if scheduled properly, it is advised to operate only three HT compressors. This will save 5.7 Million kWh electrical units annually.

Annual savings : Rs. 25.7 Million per annumInvestment required : Rs. 4.0 MillionPayback period : 2 months

2• Presently, the Khosla compressors are being used to supply air at 8 kg/cm to the boiler/instrumentation. During the audit it was found that the LP air

2compressors were also operating at 8 kg/cm and since there was surplus capacity of these compressors, seldom the excess air compressed by these air compressors is vented out at high pressure. It was recommended that instead of venting this high-pressure air, which represents energy loss, this air should be used to

Annual savings : Rs. 0.35 Million Investment required : Rs. 0.03 MillionPayback period : 1 months

- Installation of back pressure steam turbine in place of PRDS

To meet HP steam requirement, a PRDS was installed to convert VHP steam to HP steam. It was recommended to install a backpressure steam turbine in place of the PRDS. The turbine would facilitate power extraction to the extent of 2 MW and simultaneously expand the steam to the required level of

240 kg/cm . A saving of 9.1 Million kWh per year can be achieved.

Annual savings : Rs. 40.9 Million Investment required : Rs. 37 MillionPayback period : 11 months

• Furnaces

- Improve the furnace insulation

The surface temperature at various portions of the operating furnaces were found to be high. By improving the insulation at hot spots, a saving of 0.22 MMSCM of natural gas per can be achieved.

Annual savings : Rs. 22.3 Million Investment required : Rs. 1.75 MillionPayback period : 1 month

- Reduce blow down from Furnace # 3 and # 4

The blow down rate of Furnace#3 and Furnace#4 was high compared to thatof Furnace#1 & 2. The excess blow down from these two furnaces isestimated to be 6 TPH. By reducing the blow down rate of these twofurnaces to the optimum level, a saving of 0.3 MMSCM of natural gas per year can be achieved.

Annual savings : Rs. 3.3 Million Investment required : NILPayback period : Immediate

Electrical Systems

• Transformers

A complete loading analysis of the transformers was carried out. Theloading pattern showed that in most of the cases, the loading was on thelower side. For most of the transformers the best efficiency point was inthe loading range of 40-50%, but the transformers were found to beoperating at a lesser load. This has basically been done so as to have highplant operating reliability. For the sake of reliability, the plant has compromised on higher transformer losses, which is justified owing to thecritical & continuous operating schedule of the plant.

• Capacitors:

The billing from the state electricity board was based on kVAh and hence it

229228

kWh per year.

Annual savings : Rs. 5.3 Million Investment required : NominalPayback period : Immediate

• Installation of variable speed drives for pumps in DM plant and CPU plant

Recirculation valves are installed to degasser water pump, condensatefeed pump and polished condensate transfer pump. It was recommended to install VSD to these pumps to avoid recirculation thereby saving 0.33 Million kWh per year.

Annual savings : Rs. 1.5 Million Investment required : Rs. 2.1 MillionPayback period : 17 months

• Replacement of DM water transfer pumps with one large pump coupledwith VSD

DM water transfer pumps were operating at poor efficiency and recirculation was observed across the valve. It was recommended to replace the present pumps with one large pump coupled with VSD, saving 0.34 Million kWh per year.

Annual savings : Rs. 1.52 Million Investment required : Rs. 1.5 MillionPayback period : 12 months

• Replacement of raw water transfer pumps

Raw water collected in Reservoir # 3 is transferred to Reservoir # 1 with the aid of two pumps. It was found that the actual head was too high compared to rated head and efficiency was low. It was recommended to replace the present pumps with required head pump (32 m) and thereby achieve energy savings of 0.2 Million kWh per year.

Annual savings : Rs. 0.9 Million Investment required : Rs. 0.6 MillionPayback period : 8 months

• Installation of variable speed drive to the cooling water make up pump

During the audit study it was observed that there is wide variation in flowand pressure of cooling water make up pump. It was suggested to installvariable speed drive to the motor and control the speed by monitoring thepressure, thereby saving 0.12 Million kWh per year of energy.

Annual savings : Rs. 0.54 Million Investment required : Rs. 0.7 MillionPayback period : 16 months

supply boiler/instrumentation purposes & thus avoid the operation of the Khosla compressor. This will save 0.13 Million kWh electrical energy per year.

Annual savings : Rs. 0.6 Million Investment required : Rs. 0.1 MillionPayback period : 2 months

• As service air application require air at low pressures, it was recommended to use transvector nozzles for cleaning & service air requirements. This exercise will help save 0.09 Million kWh electrical units per annum.

Annual savings : Rs. 0.42 Million Investment required : Rs. 0.2 MillionPayback period : 6 months

• Lighting:

• It was found that lighting transformers were all under-loaded. It was advised to explore the possibility of supplying adjacent areas by a single lighting transformer so as to improve the transformer loading.

• Replacement of the conventional tube-lights, presently operating withcopper chokes, around 3500 in number, by the energy efficient T-5 tube-lights and with electronic ballast was recommended. This measure will save0.23 Million kWh units of electrical units annually.

Annual savings : Rs. 1.04 Million Investment required : Rs. 1.93 MillionPayback period : 22 months

Water Pumping System & Cooling Towers

The Plant has several water pumping systems such as cooling watersupply, raw water supply, DM water system in addition to three largecooling towers.

• Rationalisation of CT # 1 water pumps operation

GCU (Gas Cracker Unit) section has a separate set of pumps while GPU (Gas Processing Unit) & IOP (Integrated Oxide Plant) has different set of pumps with dedicated headers. It was recommended to replace the impellers of pumps and operate as a common system thereby resulting in reduction of power consumption by 5.0 Million kWh per year.

Annual savings : Rs. 22.64 Million Investment required : Rs. 10.0 MillionPayback period : 5 months

• Reduce the discharge pressure of pumps (or) replace the pumps with suitable capacity (head and flow) for CT# 2

It was recommended to verify the actual water pressure requirement and accordingly initiate the steps either to reduce the water pressure or replace the pumps with suitable head, resulting in an annual energy saving of 1.2 Million kWh per year.

231230

takes around 20 days. For offshore operation rig moves from one location to another location either by towing or self propelled. Time taken depends on the distance to be moved.

Spudding / Drilling phase: During this phase, almost all the machineries of the Rig are run and this phase consumes the maximum energy in terms of HSD. This phase continues for a period of about 100 to 120 days depending upon the depth of the well.

Production Testing phase: During this phase, the samples of the well are tested and then Rig is dismantled. This stage takes about 60 days.

5.3.1 Energy Consumption

Energy used in a Drilling rig is Electrical energy. This electrical energy is produced using captive mobile power generation units. In very rare cases, grid power is also used. The fuel for these power generation units is either HSD or Natural gas.

The primary source of energy in a Drilling Rig is the Diesel Oil for DG sets. Most of the DGs in the exploration rigs in India are old and de-rated and are expected to consume higher fuel as compared to the design.

5.3.2 Basic Process Flow Diagram

SPUDDING

DRILLING

MUD

CIRCULATION

if casing depth ok

CASING

CEMENTING

HERMETICALLY

SEALING

If targetdepth ok

STOP

YES

NO

NO

YES

Figure - 5.1

• Interconnection of RWTP # 1 and RWTP # 2 tanks and avoid the pumpoperation

Filtered water is stored by the plant in two tanks. Both the tanks are at the same ground level. Water is transferred from one tank to the other using a pump. It

was recommended to interconnect these two tanks at the bottom level to avoid the operation of pumps and result in annual energy saving of 0.3 Million kWh.

Annual savings : Rs. 1.3 Million Investment required : Rs. 0.5 MillionPayback period : 5 months

5.3 Energy Efficiency In Exploration Activity (Rigs)

Crude oil exploration is a very costly operation. The main equipment foroil exploration is a drilling Rig.

Generally the Rig consists of the following machineries:

1 Main Derrick consisting of a drilling platform, cat walk platform and twobig pulleys. The upper pulley is called the Crown Block and the lower onecalled Traveling Block, through which, the winch is moved by Drawworks. The Draw works may be electric driven or mechanical driven. TheDraw works drills the well with the help of drilling bits and shroudedpipes.

2 DG Sets, which are the heart of the Rig supplying power during drilling aswell as Rig building phase.

3 Mud pumps for the circulation of mud during drilling and well formationand as and when required.

4 Supercharger pumps to supply mud to the suction of mud pumps5 Desilter pump for the purpose of desilting from dirty mud coming out

from the well.6 Desander pump for the purpose of removing sand from the dirty mud

coming out from the well7 Air compressors to cater air to winch, clutch and Twin stop cam counter of

Draw works.8 Agitators for the purpose of mixing of mud 9 Shale shakers10 Degasser11 Fuel Tanks & Fuel pumps12 Eddy current Brake for control of Draw works13 Bunker Lab for the testing of mud quality14 Bunker housing15 Cranes16 For floating rigs - anchors or dynamic positioning system. For self

propelled drill ships - propulsion system.17 Water maker to produce drinking water on the rig18 Cementing unit - to cement casing against formation.19 Blow out preventor - to control well pressure.

Total operation of the Rig consists of following three phases:

Rig building phase: During this phase, the skid mounted portable machineriesare transported to the site by tailor trucks and are being installed. This stage

233232

5.3.4.2 Efficient Operation of Mud Pumps

This is the single largest load on a Rig consuming 50 to 60% of total energy consumed on a rig.These have an operating pressure of 5000 to 7000 psi and hydraulic efficiency is normally more than 90%.Reciprocating Pump operates at constant efficiency levels and hence has constant losses. Below are some general measures for energy conservation in a mud pump operation:

• The biggest culprit for energy wastage in mud pump is idling during lunch & shift changeover and higher discharge rate.

• Under loading of the prime mover is another fuel wasting situation. • Suction starvation can cause performance loss and failure of pump. • Entrained gas may reduce suction Efficiency• Each pump should feed Separate Mud Processing Equipment.

0• Mud temperatures of 66 C can present critical suction problems • A poorly designed discharge manifold can cause shock waves and

excessive pressure peaks • Excessive solids can:

1) cause wears on drilling equipment2) reduce ROP (Rate of Penetration)3) cause a thick and permeable filter cake and fluid loss4) cause unwanted pump exertion

5.3.4.3 Efficient Operation of Agitator

The following information must be known to properly size an agitator system:• Tank and compartment dimensions• Compartment shape• Compartment duty (solids removal, testing, suction, storage, or pill/slug)• Maximum mud density expected • Coupling of multiple agitators to one motor• Agitator & mud gun combination gives better agitation

5.3.4.4 Efficient Operation of Air compressors

• In a rig, compressed air is used for pneumatic control; start up operation of DG sets etc.

• Regular maintenance should be undertaken as per schedule • All air leakages must be plugged• In many installations, the compressors are manually switched on/off at the

required pressure. Installation of automatic pressure switch with predetermined setting can save wastage of energy.

• Use of automatic drain valve in the air receiver. By using the auto drain valve, water would only be allowed to pass intermittently depending on the water level in the air receiver, thereby minimising the wastage of compressed air.

5.3.4.5 "Deep Trek" and Other Drilling R&D

The U.S. Department of Energy's Office of Fossil Energy kicked off the 'Deep Trek' Program in 2002 to help develop high-tech drilling tools that industry needs to explore the deeper deposits of hydrocarbons. The goal was to develop a "smart" drilling system tough enough to withstand the extreme temperatures,

5.3.3 Energy Management Plan

The measures identified may be short term, medium term or long term requiring nil to high investments. Medium & Long term efforts are structured and normally implemented without much efforts. One example of long-term efforts is the replacement of outdated, energy inefficient DG engines like D 399 by new energy efficient models like CAT 3516 requiring high investment of the tune of Rs 250 Crores.

However short term programs are basically voluntary and needs to be push forwarded by:

• Awareness generation• Leadership demonstration• Top management support

A good energy management plan for a Rig should generally comprise of:

- Fuel consumption to be compared with specific energy generation.- Proper log sheet for regular energy monitoring- Instrumentation / software to facilitate energy logging and evaluation

of specific energy generation.- Energy monitoring based on norms developed.- Energy monitoring to be based on drilling depth and soil condition.- Segregation of AC and DC loads and have power packs dedicated

to AC and DC operation.

5.3.4 Best Operation Practices in Rigs

Best Operating Practices (BOP) is referred to operating procedures and good house keeping habits for reducing the wastage of energy, reducing & preventing environmental pollution. The overall philosophy of BOP is to conduct every day activity in more efficient, safe and environmentally sound manner.

5.3.4.1 Efficient Operation of DG sets

• When the total running load during non-drilling days is small (in the range of 50 KVA), a smaller rating ( say 63 KVA) DG set should be used during non-drilling days

• Monitoring of specific energy generation ratio (SEGR). SEGR of a DG set is a performance indicator, which is proportional to the extent of loading of the set. At part load operation, the efficiency of the DG set drops with consequent decrease in the SEGR value. Proper monitoring of SEGR will help in conserving energy.

• Monitoring of Lube oil quality. The drain interval of lube oil specified by the manufacturer is based on worst operating conditions and a high factor of safety.By follow of good operating and maintenance practices, there is a distinctpossibility that the condition of the lube oil remains good and usable evenafter the specified period.

• Testing of lube oil for certain physicochemical properties like viscosity, total base number, water content, insoluble build up etc, may extend the drain interval for lube oil.

235234

horizontally.

e) The Microhole Technology

The Microhole Technology drills small diameter boreholes (approximately two-inch diameter), using smaller sized equipments to complete microholes, and advanced diagnostic tools to measure important reservoir characteristics. The cost reduction using this technology is estimated to be nearly one-half the cost of traditional drilling rigs. The feasibility of microhole technology has been demonstrated by pioneering work conducted by Los Alamos National Laboratory (LANL) in collaboration with Maurer Technology. The team has successfully used coiled-tubing-deployed micro drilling to drill wells as small as 1-3/4-inch in diameter and as deep as 800 ft.

5.3.5 Energy Conservation Measures In Drilling Rigs

The heart of the drilling rig is the Power Packs i.e., the DG sets which are generating power for the entire Rig by using HSD in diesel engines .The consumption of HSD in the DG sets varies between 500 lits per day to 2500 lits per day depending upon the following factors:

1. Location (formation type)2. Drilling hole diameter3. Drilling depth4. Health of the DG engines5. Pull out practice (operation of drillers foot, pull out time per pipe)

The most important factor out of the above points is the health of the DG engines. The health of engine plays the major role in the oil (HSD) consumption in the Rig. For example one of the Rigs operating in India in the north east part of India is being operated with maximum 3 nos. of DG sets for a drilling depth of about 2500 Meter and at the same time with almost same formation and same drilling depth the other Rig is being operated with 4 nos. of DG sets (both the places the ages of the engines are almost same). The reason for the same is better maintenance prevailing in the first site.

Good Maintenance Practices

Checking schedule

1. Name of the parts Checking after

Liner 200 HrsPiston 200 HrsValve insert 24-36 HrsValve spring 24-36 HrsValve cover gasket 24-36 HrsWater Valve 24-36 HrsValve Sheet 24-36 Hrs

pressures and corrosive conditions of deep reservoirs, yet economical enough to make the hydrocarbons affordable to produce. The projects include advancing drilling performance, developing "smart" communication systems, instrumentation, novel drill bits and fluids, and novel pipe systems that are able

oto withstand the severe temperatures (over 400 F) and pressures in deep horizons.

These "smart" drilling systems can report key measurements - temperature, pressure, fluid content, geology, etc. - as a well is drilled. Sophisticated electronic systems can identify potential trouble spots on a real-time basis, allowing operators to make adjustments without interruption or costly work stoppages.

5.3.4.6 Other Drilling Advancements

a) Mud Pulse

It is the first system to transmit drill bit location by sending pressure pulses through drilling mud, which was developed by the US Energy Department and Teleco, Inc. Today, this "mud pulse" measurement-while-drilling telemetry has become standard in the industry.

b) IntelliPipe

A new technology system in downhole telemetry, sponsored by US DOE called IntelliPipe turns an oil and gas drill pipe into a high-speed data transmission tool capable of sending data from the bottom of a well up to 200,000 times faster than mud pulse and other downhole telemetry technology in common use today. Potential benefits include decreased costs, improved safety, and reduced environmental impacts from drilling.

c) New drill bits

The polycrystalline diamond (PDC) drill bit, now the industry standard for drilling into difficult formations, is a Revolutionary new drill bit developed by US Energy Department's research program. Scientists at the Energy Department's Sandia National Laboratories have successfully developed a "diffusion bonding" approach. More recently, Penn State University, working under an Office of Fossil Energy contract, developed a way to use microwaves to harden the tungsten carbide of deep drilling bits, resulting in a 30 percent increase in strength.

d) Advanced composite drill pipe materials (Carbon fiber)

The drilling system of the future may also employ new advances in drill pipe materials as a result of the Energy Department's research program. In mid 2004, the Department announced the development of a new "composite" drill pipe that is lighter, stronger and more flexible than steel, which could significantly alter the ability to drain substantially more oil and gas from rock than traditional vertical wells.

The carbon fiber drill pipe is likely to weigh less than half the weight of steel drill pipe, and the lighter the pipe, the less torque and drag is created, and the greater distance a well can be drilled both vertically and

237236

advantage of this is that at a time 3 strands can be put together for drilling operation. Hence the total time for drilling can be reduced considerably. But at the same time fuel consumption will increase during drilling phase because of additional load of electrical TOP DRIVE in place of conventional mechanical Rotary Drive. However overall energy saving is envisaged to be less in such rig operation due to less no of days required for drilling. As per GTO (Geo Technical Order) the total number of days envisaged was 368 days but as per actual status this rig operation has been estimated to be 300 days that too including 45 days of idling due to problem in the newly installed TOP DRIVE system.

Study Of Energy Consumption Pattern - Preceding Three Years

Rig was commissioned in March 2005 after total overhauling of DGs.

Details Of DG Engines

* Trials were taken by isolating DGs from the existing fuel oil system and using half cut drum for supplying HSD fuel to DG set and recording the dip before and after the trial.

SFC (Specific Fuel Consumption, lit/kWh) of DGs of the rig

YEARS Parameters 2002 - 2003 2003 - 2004 2004 - 2005

HSD (LT) Consumption 762098 1228036 147420 POL (LT) Consumption 14910 28560 1100 MTR DRILL 7869 4752 2335 kWh/MTR 352.53 940.67 134.76 TOTAL kWh 2774058 4470064 314673 SFC 0.2747 0.2747 0.468

Sr No

Item

DG 1

DG 2

DG 3

DG 4

GENERAL1 Engine serial no. 2XJ00014 36Z02060 36Z01988 36Z01525

2

3

Peak Load (kVA) 600 600 600 600

Total Working hrs. (Present Well) 276 276 276 276

FUEL4 Type of fuel

HSD (Diesel)

HSD (Diesel)

HSD (Diesel)

HSD (Diesel)

5 Fuel Density

0.865 at 150C

0.865 at 150C

0.865 at 150C

0.865 at 150C

6

Method of checking fuel quantity

Manual By Tank Dip Manual By Tank Dip

Manual By Tank Dip Manual By Tank Dip

17 Fuel Consumption of Present Well (as on 11.08.05 in Lts.)

991037 Lts

NO. OF DG SETS IN RIG: 04 (FOUR)

ENGINE PARTICULARS

Present status (SFC) * Design parameter (SFC) S.no. Make

Capacity

1

2

3

4

DG ID

DG 1

DG 2

DG 3

DG 4

CATERPILLAR

CATERPILLAR

CATERPILLAR

CATERPILLAR

Model

D 399

D 399

D 399

D 399

Engine sl.No.

2XJ00014

36Z02060

36Z01988

36Z01523

1215

1215

1215

1215

25%

0.35

0.37

0.34

0.385

50%

0.31

0.325

0.31

0.365

75%

0.30

0.329

0.30

0.355

100% NA

NA

NA

NA

25%

0.324

0.324

0.324

0.324

50%

0.2743

0.2743

0.2743

0.2743

75%

0.2617

0.2617

0.2617

0.2617

100% 0.2674 0.2674

0.2674

0.2674

Daily Checking

ØLube oilØRadiator water & Radiator capØBearing condition (visually)ØBeltØLeak of FuelØOilØAir cleaner box indicator

Quality of Radiator water plays a very important role. If possible DM water may be used and 20% coolant to be used along with the radiator water. This will ensure at least 0.5 % saving of fuel (HSD) in DG engine

Fluid end part

Name of the parts Checking after

Valve insert 24-36 HrsValve spring 24-36 HrsValve cover gasket 24-36 HrsWater Valve 24-36 HrsValve Sheet 24-36 Hrs

Lube Oil

Lube oil selection and use plays an important role in the efficiency of DG engines

ØLube oil consumption tells about the health of engine. Appropriate specific lube oil consumption for D-399 Caterpillar engine is 0.5 lit/hr. If the oil consumption goes higher than this value, engine needs attention.

ØLube oil to be changed after every 1000 Hrs (of course after checking the quality as mentioned below)

ØUse 15 W-40 after talking to OEM, in place of SAE30 as recommended by OEM.

ØCondition monitoring may be started after every 250 Hrs with the help of portable analyzer kit (cost around Rs 35000/-)

ØLube oil to be changed when the following conditions appear

• TBN (Total Base Number) : Variation of 50% of original value.• Flash point : 50 Degree below the original value.• Viscosity (centistokes) : 25 ± original value.

Maintaining the condition of lube oil of DG set will ensure increased efficiency of the engine and a saving minimum 0.5 % HSD consumption as compared to deteriorated lube oil.

Case Study 2: Energy Audit at an Onshore Drilling Rig

About The Rig

All the DGs / Alternators are totally overhauled during July/ August 2004 and put back for use in THE RIG in March 2005. The Power Control Room (PCR) of the rig is absolutely new and its make is National Oil Well (Model 2001). The rig is unique as it is the only rig where Variable Frequency Driven TOP Drive system has been implemented in place of Rotary Drive System for the first time in Assam Region. The

239238

Present Fuel Consumption Of DG Sets

SFC of DG 1 (at 35% loading) : 0.33SFC of DG 2 (at 35% loading) : 0.33SFC of DG 3 (at 35% loading) : 0.345SFC of DG 4 (at 35% loading) : 0.37

SFC Curve of DG 1

Actual vs Design SEC CURVE (% Loading of DG vs consumption of HSD) of DG engine will give the clear picture about the health of DG set at a particular point of time. More the gap between the actual and the design curve, more the aging of the engine and more care is required in terms of maintenance.

Energy savings

No Cost Option

Medium Cost Option

High Cost Option

SFC CURVE OF DG 1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

0 20 40 60 80 100 120

% LOADING

SF

C,L

IT/K

WH

r

SFC(DESIGN)

SFC(ACTUAL)

SAVINGS POTENTIAL INVESTMENT (Rs. in lakhs)

PAYBACK MONTHS

SL. NO.

DESCRIPTION

KLOE / MONTH

Rs. (Lakhs/m

onth)

1 Running of each DG at minimum loading of 35%

21.2 6.78 - Immediate

(Million/month)

0.678

SAVINGS POTENTIAL INVESTMENT (Rs. in lakhs)

PAYBACK MONTHS

SL. NO.

DESCRIPTION

TOTAL KLOE

Rs. (Lakhs)

1 To install one no. of 125 KVA DG set to run during production testing, logging and rig building phase

13.5 4.32 8 22 months

Millions

0.432

SAVINGS POTENTIAL

INVESTMENT (Rs. in lakhs)

PAYBACK MONTHS

SL. NO.

DESCRIPTION

TOTAL KLOE

Rs. (Lakhs)

1 To run DG at 50% load min. in stead of 25% by installing 4 nos. of APFC at the PCR, 2 nos. of fixed capacitor bank at the DBs of 1000 HP DC motor and to install 6 nos. of soft starters

45.6 14.59 9 22 months

Millions

1.459

Estimation Of Saving Potential During Drilling Phase

Basis:

1. Average SFC estimated at an average loading of 25% (including drilling and idling period) during the drilling phase at 1400-23 Rig = 0.4249 lit/kWh(DG 1: 0.4219, DG2: 0.4295, DG3: 0.4269, DG4: 0.4212)

2. Average loading of DG set is increased to minimum 35% from the present average loading of 25% so as to decrease the average SFC from 0.4249 to 0 .3675 (DG 1: 0.36, DG2: 0.3675, DG3: 0.3825, DG4: 0.36)

3. Monthly average kWh measured during the trial = 370800 kWh.

Estimation:

Hence if the DGs are run at minimum loading of average 35% instead of average 25% loading monthly saving = 370800 (0.4249 - 0.3675) = 21284 lit

= 21.2 KL of HSD = Rs. 0.678 Million

Savings Due To Installation Of One 125 kVA DG Set For Running During Rig Building, Production Testing And Logging Operation And Simple Pay Back Period.

Basis:

1. Load during day time : 60 kW2. Load during night time : 90 kW3. No. of days of duration for production testing and : 75

logging and Rig building phase4. SFC with 125 kVA DG set with 75 % loading : 0.300 (at 75% load)5. SFC with existing big DG with 10% loading during : 0.40

production testing, logging operation

Estimation For The Energy Saving

1. Total Energy required during 75 days at day time = 75 (days) x 60 (kW) x 12 hrs = 54,000

2. Total energy required during 75 days at night time = 76 (days) x 90 x 12 = 81,000 Hence total energy required during 75 days = 54000 + 81000 of production testing, logging period = 135,000 kWh3. HSD consumption to generate 135,000 kWh of energy by big caterpillar engine with SFC of 0.4 lit/KWhr at an average loading of 10% = 135,000 x 0.40

= 54,000 lits of HSD 4. HSD consumption to generate 135,000 kWh of energy by 125 kVA DG set with SFC of 0.3 lit/KWhr at an average loading min 75% =1,35,000 X 0.3

= 40,500 lits of HSD5. Hence total saving of HSD = 54,000 - 40,500 = 13,500 lits

= Rs. 0.432 Million

Pay Back Period For The Installation Of 125 kVA Smaller DG Set

1. The investment required = 0.8 Million2. Savings expected = 0.432 Million

(during 75 days of production testing logging) 3. Payback period = (0.8 / 0.432) x 12 = 22 months

241240

Installation Of Capacitor Bank

The main problem of a drilling RIG is the power factor of power generated by the DG engines. Due to sudden change of load in the RIG due various reasons the DC load of Draw works and mud pump (AC load of DG is getting changed to DC with the help of SCRs to supply DC power to Draw works and Mud pump). As the DC load increases or decreases the power fluctuates from as low as 0.2 to 0.65 resulting KVA demand (KW/PF) fluctuation. The poor factor actually force the electrical man in the RIG to run additional engines for safety factor so as to avoid black out situation. This results in poor loading of individual DGs resulting high consumption of HSD at poor loading.

One solution for improving and sustaining the power can be installation of automated power factor controller. But globally there is no instance for adopting such APFC. However efforts can be made in this direction on experimental basis.

Estimation Of kVAr Requirement For The Capacitor Banks

Calculation of KVAR for APFC (for installation at the common outlet of all the DGs)

-1 -1kVAr requirement = Maximum load (kW) [tan (cos Ø 1) - tan (cos Ø 2)]Where Ø1 = 0.4 (av. PF of the system) Ø2 = 0.7 (max. PF that can be achieved)

-1 -1 = 1250 [ tan (Cos 0.4) - tan (Cos 0.7)]= 1250 [tan (66.42) - tan (45.57)]= 1250 [2.29 - 1.02]= 1587 1600

Hence four nos. of APFCs of each 400 kVAr capacity in series can be put at the PCR (Power Control Room) to improve upon the PF.

Estimation Of Savings Potential By Improving The Power Factor (From 0.4 To 0.7) And Reducing The kVA Demand Of The Rig

Basis:

1. Existing avg. PF of Rig = 0.42. Improved PF of Rig after installation of APFCs and fixed type Capacitor Bank = 0.653. Present average loading of DGs is 25%

Estimation For Saving

1. One DG can be stopped by reducing the peak demand from 1250 kW max (3125 kVA) to 1925 kVA with the help of capacitor (Automated and fixed). By this in extreme situation, instead of running 4 DGs (each DG can take care 970 kVA max (80% of 1215 kVA limited to alternator). 2 DGs can cater the same load.

2. On the safer side if 3 DGs run in place of 4 DGs during the entire period of the rig operation, operation of 1 DG can be stopped.

3. Considering stopping of one DG throughout the rig operation thereby increasing the loading by around 25% (from 25% loading to 50% loading) the SFC can be reduced from 0.3220 to 0.3025 (refer actual SFC curves of DGs)

4. Considering the total power requirement of 2340200 kWh (estimated earlier) during the entire period of Rig Operation and a reduction of SFC by 0.0195 lit/kWh.

Total Saving = 45634 lit/kWh of HSD = 45.6 KL/HSD = Rs 1.459 Million

5. The payback period for the above investment = 0.9 Million (investment) x 12 = 7 months

1.459 Million5.4 Activities of Conservation of Oil and Gas in ONGC

ONGC has taken many steps for conservation of energy. One of the examples of its long-term efforts is the plan for replacement of all D-399 engines by new energy efficient engines model CAT 3516 at a cost of about Rs. 250 Crores. These CAT 3516 engines are 5% more efficient.

5.4.1 Year wise consumption in ONGC

5.4.2 Steps initiated to conserve Petroleum products

ONGC's program of oil conservation is briefly summarized as below:

(A) Action Taken In-house For Conservation

a) Awareness Program is held every year under OGCF (Oil & Gas Conservation Fortnight)

b) Seminar / Conference is organized for deliberation of issues on petroleum conservation.

c) ONGC Energy policy is already framedd) Energy Conservation tips are continuously scrolled on ONGC's house portal.e) E.C. Committee has issued two policies on conservation as under• Use of Solar Water Heating Systems in ONGC• Use of Energy Efficient Lighting System in ONGCf) On line quiz being held every year for ONGC employees and their wards.g) Three booklets are issued on conservation of Oil & Gas.• Urja Udai• Energy Conservation Techniques• Quest

h) A company wide training drive as "Energy Conservation Techniques Training" has been taken up with the help of PCRA for training about 20000 officials of ONGC.

i) All models of engines have been audited and corrected for their running efficiency.

j) 285 CAT D-399 Engines being replaced in phased manner by CAT D-3816 Energy Efficient Engines.

k) Solar Water Heating Systems of different capacity has already been installed on following locations in ONGC.1. 1300 Litres Per Day (LPD) at ONGC Guest House Tel Bhawan, Dehradun.2. 9000LPD at ONGC Hospital Dehradun.3. 7200LPD at GT Hostel in ONGC Academy.4. 7200LPD at ONGC Colony Dehradun.

Year 2006-07 2007-08

HSD in KL 196440.7 215419.4

Natural Gas in MMSCM 1602.5 1739.6

243242

5. 800LPD at Officers Club ONGC Dehradun.

l) 50MW Wind Power Project has been installed in Gujarat, near Bhuj. With asaving potential of Rs. 29.86 Crores/Year.

m) More then 200 Energy Audits Carry outs on the different ONGC Installations.

(B) Expected reduction in consumption (from major initiatives)

1. "Energy Conservation Techniques Training" 3- 5%2. Solar Water Heating Systems in ONGC 5-10%3. Wind Power Projects 10-15%4. By Energy Efficient Engines (Caterpiller) 14-17%5. By Energy Efficient Engines (Cummins) 3-7%

(C) Strategies for Conservation In Future

II. Additional awareness program in the organization to be taken up.III. More policies of Energy Conservation are to be put up for application.IV. Additional Solar/Thermal systems to be installed on more areas.V. Additional new Wind Power Plants to be set up in future.VI. First time Geothermal Energy project to be taken up.VII. Replacement of inefficient equipments.VIII. Tapping up waste heat recovery from exhaust of engines.IX. Waste heat recovery from Engines Jacket Water/RadiatorX. Solar Electric SystemXI. Ocean Energy

5.5 Energy conservation measures in Oil India Limited (OIL)

5.5.1 Present Level Of Energy Consumption By OIL(During 2007-08)

5.5.2 Various Measures Adopted By OIL For Conservation Of Energy During The Year 2007-08

5.5.2.1 Conservation Of Crude Oil

A total quantity of 4431 kL of Crude oil has been saved/retrieved from different operational activities during the year under review by adopting the following measures:

Energy Unit Qty Eqvt.kWh Approx. Monetary value(Rs. in Lakh)

Crude Oil Consumed for

Transportation of OIL’s &

ONGC’s crude Oil to refineries, etc.

kL

8069.00

78.269 × 10 6

1690.50

Natural Gas (industrial &

domestic uses) MMSCUM

370.07

4266.90 × 10

6

11842.24

Diesel oil (HSD) (Drilling & W.O. operations, prime mover operations, power generation, transport fleet, etc.)

kL 13397.64 107.964 × 10 6 4342.175

L.D.O.

kL

7.20

0.07 × 106

2.70Petrol kL

68.77

0.65 ×10 6

32.72 K.Oil

kL

0.942

0.09 ×10 6

0.015Lube Oil kL 771.061 *** 652.93Electricity kWh - 111.00 ×10

62053.50

TOTAL 4564.947× 10 6

20616.78

• Use of Aluminium paint in all crude oil storage tanks to minimize evaporation loss.

• Use of Oil Soluble De-emulsifier (OSD).• Use of dual fuel (Natural Gas and Crude Oil as fuel) engine in Crude Oil

Dispatch Pumps in PS-1 & PS-2 since natural gas is available.• Regular & proper maintenance of Crude Oil Transportation Trunk/ Branch

Pipelines to minimize pumping power requirement. This is further reduced by treating the crude oil with flow improver chemical / heat treatment.

• Water Clarification Plant and use of De-Oiler.• Retrieved from various pits and sumps.

5.5.2.2 Recovery of Condensate

Total volume of condensate recovered during the year was about 65604 kL, which in terms of money amounts to Rs. 13744 lakhs (approx.)• By the operation of condensate recovery plant (CRP) at Moran, a total quantity of 3957 kL condensate recovered. • Condensate recovered from Duliajan field -61236 kL • Condensate recovered from Rajasthan project- 356 kL

5.5.2.3 Conservation Of Natural Gas

Reduction in natural gas consumption in COCP's at Duliajan and Moran

During the year, the crude oil of both OIL & ONGC was treated with Flow Improver chemical instead of thermal conditioning and thereby the consumption of natural gas in COCPs at Duliajan has been reduced considerably and as a result the total saving of natural gas was around 6.84 MMSCM (amounts to Rs.218.8 lakhs approx.) during the year 2007-08.

Reduction of Gas flare

The following steps were taken for the reduction of natural gas flare during2007-08.

1 Gas flare in Moran field has been reduced to 0.05 %.22 A total of 1.1 MMSCM very low pressure gas (about 0.7 kg / cm stabilizer

gas which is normally being flared in many OCSs) is being utilized fromMoran OCS as domestic fuel in housing area.

3 After commissioning of stabilizer compressor and water seal system at OCS-5,2utilized 1.1 MMSCM low pressure stabilizer gas (0.7 kg / cm ) as housing

fuel which otherwise would have been flared.4 After commissioning of two nos. gas distribution pipeline to utilize associated

gas produced at Brekuri EPS and NKL/NKL QPS, resulted in reduced gasflaring and saving of 2102500 SCM of natural gas.

5 During the year 160392 SCM low-pressure gas (30 psig) of Deroi EPS soldto Moran Gas Grid. When there is no demand of gas from Moran Gas Grid,20892 SCM of 30 psig low pressure gas from Deroi EPS was diverted toMoran GCS-2, which otherwise would have been flared.

6 Gas Holder: With the commissioning of the 30 psig Gas Holder the gas flaringcaused by surging effect of the gas lift has been restrained.

7 Setting of Flare Controller: Periodic (weekly) flare controller setting at 35 psigis being carried out to avoid flaring of 30 psig gas at various OCSs.

245244

5.5.2.4 Supervisory Control And Data Acquisition (SCADA)

The SCADA project commissioned on 15 March 1998 is presently being used to control the gas flare, accurate gas measurement, monitor consumption of gas as fuel in both Oil Collecting Station (OCS) and Gas Compressor Station (GCS) and for maximum utilization of produced gas, etc.

5.5.2.5 Conservation Of Diesel (HSD) And Petrol

Total quantity of about 406 kL (amounts to about Rs. 132 lakhs) of diesel has been conserved during the year under review by adopting the following measures:

1 By installation of Gas Engine driven Crude Oil Dispatch (COD) pump inplace ofDieselEngine Driven Bowser loading pump at Barekuri EPS about 25.55 kL of HSD are being saved.

2 Eight nos. of work over wells were provided with electrical power from nearestavailable source, resulted in saving of 9.6 kL of HSD.

3 Use of solar lighting at Tanot-GGS (Rajasthan) & Pilot Plant at Baghewala(Rajasthan), resulted in saving of 2.84 kL of HSD

4 In pipeline operation 45 Nos. of old Dorman engines of generating sets havingfuel (HSD) consumption in the range 3.6 to 4.0 Ltr/Hr, at various repeaterstations have been replaced by Koel engines having fuel consumption rate of2.6 to 2.8 Ltr/Hr., which resulted in saving of about 150 kL of HSD.

5 By using PDC Bits that cuts down the round trip time and resulting in reductionof the rig hours consequently there is considerable reduction in HSDconsumption.

6 By adopting and continuing cluster-drilling techniques, consumption of fuel(particularly HSD) is reduced considerably. Rig dragging were carried out atfive different locations whereby a rig was moved onto next cluster locationwithout any rigging down operation. This additionally eliminates rigmovements, which resulted in considerable saving in HSD consumption.

7 By adopting Horizontal Drilling technique, three full plus three part horizontalwell were completed. Production from a horizontal well is three times than of aconventional well thereby saving in construction cost of two well as well asconsiderable saving in HSD consumption.

8 By using motor driven hydraulic power unit instead of engine driven hydraulicpower unit for torque up casings during drilling operation resulted inconsiderable saving in HSD consumption.

9 Minimized workover and swabbing operation wherever feasible by using CoilTubing Units (CTU) - Nitrogen Pumping Units (NPU). During the year2007-08 total 129 nos. of work-over equivalent job were carried out bydeploying CTUs & NPUs, resulted in saving of 218.4 kL of HSD

10 By replacing diesel engine driven centrifugal pump by motor driven pump indrilling rig for pumping gauging water, considerable amount of HSD wassaved.

5.5.2.6 Conservation Of Lube Oil

1 By using Lube oil analysis kit, carrying out Chemical analysis from time to time and revising and setting up of lube oil standard, the lube oil consumption has been optimized which in fact contributed to the conservation of lube oil. The lube oil change period for caterpillar engine has been re-scheduled from 500 Hrs. (manufacturer's recommendation) to around 1000 Hrs. (OIL's practice) without any adverse affect on the engine, which resulted considerable saving of lube oil.

2. Due to use of improved quality of gland packing of the plungers of the injection pumps in Water Injection operations the consumption of lube oil was reduced considerably.

5.5.2.7 Utilisation Of Non-Conventional Energy

I. A total of about 244 nos. of Multi Access Radio Telephone (MART) terminals were provided with Solar Photo Voltaic Panels to achieve energy saving and cost reduction. By adopting these measures about 0.61 kL of HSD was saved during 2007-08.

II. Use of solar lighting at TANOT Gas Gathering Station and at Pilot plant, Baghewala resulted in saving of 2.84 kL of HSD.

References

1. Petroleum exploration and production activities, 2006-07, Directorate Generalof Hydrocarbons, Ministry of Petroleum & Natural Gas, GoI

2. Annual Report (2007-08) of Ministry of Petroleum & Natural Gas, GoI3. World Energy Outlook 20074. TERI Energy Directory and Yearbook 20075. Statistical Abstract 2007-CSO6. Report from Technical Services & Energy Conservation Cell of ONGC7. Report from Technical Audit Department, OIL INDIA LIMITED8. Energy Audit Reports of ONGC & OIL conducted by PCRA9. BP Statistical Review, June 200810. PPAC Ready Recokner, April 200811. www.netl.doe.gov12. www.fossil.energy.gov

247

Notes

6.1 Introduction

Over 100 million LPG consumers in the domestic sector in India are serviced through a network of 9365 LPG distributors who are getting supply from 181 LPG bottling plants located across the country. In 2007-08, India consumed a total of about 1170 TMT of LPG which is around 10% of the consumption of total petroleum products in the country. Out of the total LPG consumption during the year 2007-08, almost 75% was used for cooking, 17% as auto LPG and the remaining 8% for industrial use. Of the total supply of 11.7 Million Tonnes of LPG during 2007-08, the indigenous production was 8868 TMT from crude oil and natural gas fractionation (3:1). Imports by PSUs and private entrepreneurs accounted for 2156 TMT and 673 TMT respectively.

LPG is transported from production installations i.e. Refineries, Fractionation plants and Import terminals to the bottling plants through pipelines, Bulk LPG Wagons or Bulk LPG Tank Trucks. This LPG, subsequently, is bottled in 19 Kg, 14.2 Kg and 5 Kg cylinders and is then delivered to commercial consumers and individual households. Bottling operation of LPG is very critical, as LPG is a highly inflammable product and the systems are required to be intrinsically safe. The systems also require very comprehensive fire safety arrangements.

A typical LPG bottling plant has the following major energy consuming equipment:-

1. LPG pumps2. LPG compressors3. Conveyors4. Blowers 5. Cold repair facilities including painting6. Air compressors and air drying units.7. Transformer, MCC & DG sets8. Fire fighting facilities9. Loading and unloading facilities

Some of the LPG bottling plants use a comprehensive monitoring technique for keeping track of energy / fuel Consumption on per tonne basis. PCRA's energy audit studies in various LPG plants have found 20-25% energy saving potential in the LPG Plant operations. The following are major energy conservation opportunities in a LPG Plant:

6.2 Energy Conservation Opportunities in Air Compressors

Compressed air system is one of the most inefficient operation for conversion and storage of energy. Typically, efficiency from start to end-use is around 10%. In any compressed air system with a saving potential of upto 30%. This saving potential is mainly, towards efficient compressed air generation system, efficient compressed air transportation system, maintenance of optimum pressure levels and reducing misuse and leakages.

Chapter - 6

LPG Bottling Plants

249248

6.2.3 Leakage of Compressed Air & Wastage:

Avoiding leakage is the largest opportunity of saving energy in a compressed air system. The leakage in compressed air system in a plant can be quantified by adopting the following process -

a) Raising the receiver pressure to the designed pressure and stopping the air usage with all intermediate valves open.

b) Keeping the complete line including pneumatic circuit pressurisedc) Recording loading and unloading duration of the compressor

% leakage can be calculated by

% Leakage = Load Time x 100 Load Time + Unload Time

Case Study 3 : Arresting the leakage in a Compressed Air System

Brief

Leakage of anywhere between 40% to 90% has been observed in compressed air systems. Leakage can be arrested by conducting a leak test for identifying points of leakages and plugging the same. Leakage reduction is a continuous process and should be built into the system

Energy Savings

A reduction of 25% leakage in a typical 150 CFM system would mean saving of over 37 CFM. Equivalent power saving would be 6 kW having implication of 33600 kWh, worth Rs. 157000/- per year for a 16 hour per day operation for 350 days per year system.

It does not really cost much to arrest leakage, whereas the saving potential is very high.

6.3 Optimization of Power Supply System Billing and Demand SideManagement

Various equipment forming the power supply system in a bottling plant are Transformers, Breakers, Switchgears, Changeover switches, PF controllers etc. Licensed area being a notified intrinsically safe area, all these circuit elements of the power supply system are installed outside the licensed area. Thus, the length of transmission cables is longer compared to any other application and hence demand side management becomes all the more important.

On overhauling the compressor, the Annual saving in energy : 15120 kWh

Annual saving : Rs.71000.00

Investment required : Rs.25000.00

Payback Period : 4 months

6.2.1 Compressor Air Pressure Level

In a bottling plant, compressed air is used as instrument air and service air. The 2pressure level of 5 Kg/cm is sufficient for all the operations in a bottling plant.

The requirement of air pressure for various devices is as under:

2Remote Operated Valve(ROV) - 5.0 Kg/cm2Deluge valve - 3.5 Kg/cm2Stopper/pushing/pulling of cylinders - 5.0 Kg/cm

2 Instrumentation - 2.0 kg/cm2Painting gun - 4.0 kg/cm2Hydrostatic testing of cylinders - 5.0 Kg/cm

Case Study 1 : Air Pressure Level Optimization

Brief

Air pressure level in the plant is fixed by setting the loading and unloading pressure through pressure switch provided in Air Compressor.

Energy Savings

Generally, the air pressure maintained in a LPG bottling plant is of the order of 6 to 2 26.5 Kg/cm Reduction in pressure levels by 1.25 kg/cm would mean saving of

12.5% in energy consumption and saving of another 15% in compressed air consumption. For a plant having 1 carousel system requiring 150 CFM (27kW motor load) compressed air and working 16 hours per day and 350 days per year, savings of 12.5%: 19170 kWh worth Rs. 90000/- per year is possible. Additional saving of Rs. 0.11 Million per year can be achieved through reduction in compressed air consumption.

This is a no cost proposition, requiring minimal technical skill in re-setting of pressure switches.

6.2.2 Performance test and measurement of output CFM of compressor:

Air compressors, specially reciprocating, suffer deterioration in performance over a period of time, resulting in lower volumetric efficiency. The drop in volumetric efficiency needs to be diagnosed and corrected at its earliest, so as to check the loss of energy.

Case Study 2 : Measurement of output CFM

Brief

Assessment of volumetric efficiency can be done in-house with least instrumentation support. Finding the volumetric efficiency dropping by more than 10%, should trigger for initiating major overhaul. Typical overhaul of a 150 CFM Air Compressor would cost Rs. 25000/- approx.

Energy Savings

A 10% deterioration in volumetric efficiency in a 150 CFM system means, loss of 2.7 kW of power. For a 16 hour per day operation for 350 days in a year system, this works out to 15120 kWh.

6.3.1 Transformers

Transformers are very efficient electrical equipment. However, losses are still an issue in the transformers in a typical power transmission network.

Normally, two number of transformers are installed in a bottling plant with one being stand-by and both are kept energised all the time so as to avoid any power failure due to break down in transformer. However, keeping two transformers energised (one being stand-by) is a wrong practice as the transformers are under charged condition for 24 hours everyday and losses are incurred even if no power is drawn from the transformer.

Typically, a 1500 kVA modern transformer having amorphous core has a no load loss of 555 Watts. De-energisation may risk the transformer of moisture ingress. However, moisture ingress can be avoided by following a sequential on/off regime.

De-energising the transformer is not always the solution. At times load re-distribution among transformers helps reduce load losses resulting in reduction of overall loss. Typically no load losses of the transformer is of the order of 50% of load losses. Thus, opportunity for saving Energy in a transformer system needs to be assessed for the system as a whole. Implementation of the proposition involves no investment and very little technical skill.

Keep the standby transformer De-energised and load the two transformers alternately every fortnight. This will save ½ KW worth power having yearly saving potential of 1/2X24X365 4381 kWh. This saving potential may be 7 times more if Silicon Core Transformer is used and over 3 times more, if Low Loss Silicon Core transformer is used.

6.3.2 Demand Side Management

Demand Side Management involves controlling various cost heads appearing in a typical electricity bill, with a view to optimise electricity bill. The factors appearing in electricity bill are Maximum Demand, Power Factor, Voltage Levels (HT/LT) etc. All these factors can be kept under strict control, resulting in substantial saving for units.

Keeping Maximum Demand under control helps units save on demand charges, at the same time helps the utility by way of spare capacity. It is always advisable to keep maximum demand under check. This issue becomes of paramount importance, where snap loads are there. Like in a bottling plant, fire water pumps testing, service water pumping etc are not continuous loads and hence these jobs can be done in off peak hours to save on maximum demand. It will also help in cases where Time Of Day (TOD) tariff system exists. Equipment like Maximum Demand Controller is used for keeping maximum demand under control through user defined sequential switching off and on.

Average of the of time integrated load for every half an hour period is registered in the electronic meter for the entire month. The maximum value registered is considered to be the maximum demand. Maximum demand can be controlled by monitoring number of energy consuming equipments, operated at any point of time and also by improving Power Factor. Industries have started use of relay based

intelligent Maximum Demand Controllers, which keep check on maximum demand by switching off and deferring non essential loads.

In two-part tariff system, Demand Charges are levied on the contract demand. The Demand Charges have been found to be higher up to 20% of net electricity bill in a Bottling Plant. The utility also levies penalty for exceeding contract demand. Thus keeping maximum demand under control, pays through saving in demand charges.

6.4 PF Control

Power Factor is a measure of the quantum of Inductive load present in an electrical system and also the extent of partial loading of these inductive loads. Utilities (Electricity Supply Companies) give incentive for maintaining higher Power Factor and the incentive may be upto 5% of the energy charges. Maintaining higher PF has the following advantages :

2i Keeps current under check and hence the I R losses are reduced. ii Saves transmission losses, in systems having longer cable lengths.iii Power Utility companies pay incentive for maintaining higher PF. iv Helps to keep maximum demand under check and hence lowers outgo towards demand charges.v Helps in keeping voltage drop lower and hence better voltage availability and

very less voltage imbalance to help save electricity.

Automatic Power Factor Controller (APFC) helps improve Power Factor and reach near unity.

Case Study 4 : Improving and maintaining the Power Factor

Brief

Improving and maintaining the power factor from 0.93 to near unity by providing additional capacitors having kVAh billing system.

Energy Savings

Annual energy consumption = 227340 kWhExisting Average pf = 0.93Annual consumption in KVAh = 227340 kWh / 0.93 = 244452 kVAhOn improving the power factor from 0.93 to 0.99 by installing required additional capacitorsThe same annual energy consumption in KVAh = 227340 kWh /0.99 =229636 kVAhAnnual Saving of energy in KVAh = 229636 - 244452 = 14816 kVAhAverage unit rate is Rs 3.57 / kVAhAnnual Saving in Rs = Rs 52893.00Cost of additional capacitors = Rs 10,000/-Pay back period = 3 months

Case Study 5 : Improving and maintaining the power factor from 0.92 to nearunity by providing additional capacitors for system having kWh billing system and having rebate of 0.5% for improvement in PF by 0.01, on its energy charges.

251250

253252

Energy Savings:

Annual energy consumption = 442040 kWhExisting Average pf = 0.92On improving the power factor from 0.92 to 0.99 by installing required additional capacitors the improvement is by 0.07.The plant is eligible for a rebate of 3.5 % on its energy charges.

Annual energy charges @ Rs 4.09 / kWh = 442040 x 4.09 = Rs 1807944.00The rebate on energy charges = 3.5 % of Rs 1807944Annual Saving = Rs 63278.00Cost of additional capacitors = Rs 50,000/-Pay back period = 10 months

The Demand control through scheduling of loads and also with the help of MDI controller is a proven solution working in industrial applications and is very reliable. Indian vendors are also available for the job. Reliable APFC and capacitors are very easily available and require little maintenance. The system may not work reliably and capacitors may fail, if harmonics are there in the system. APFC with harmonic filter gives comprehensive solution for systems having high harmonic distortions.

6.5 Voltage Optimization

Typically, in a transmission system, voltage at the load end, reduces with reduction in Power Factor or increase in current levels. Various loads, requiring electricity for its operation, are designed for a voltage of 415V. However, the voltage levels are generally higher and reach upto 460V during late night. This gives an opportunity to reduce voltage by upto 10%. A reduction in voltage by 10%, would give savings of upto 1.5% in motors because lowering voltage increases loading level of motors resulting in improvement in its efficiency. A 10% drop in voltage, also helps save upto 15% in energy consumption in lighting loads

There are two ways in which voltage control may be implemented -

6.5.1 Voltage control through Tap Changer

Use of Tap Changer - The provision for tap changing is an inbuilt feature of transformer / incomer system. Lowering the voltage through tap changing is the most convenient way of reducing voltage levels. It involves no cost and it is very convenient if the transformer has On Load Tap Changer (OLTC). Otherwise, every tap change involves switching off power and then effecting tap change.

6.5.2 Voltage Control through AVR

Use of AVR - Automatic Voltage Regulators have emerged as a worthy solution. AVR technology is very proven and very easily available. The advantage of having an AVR is that one can have the desired voltage out put , say 3 phase, 415 V, 24 hours a day, irrespective of the incoming voltage. This is not possible in tap changers. It immunes the system of voltage fluctuation and high voltages, especially during late night hours. AVR is a very good proposition for exclusively lighting load as the voltage levels are higher during night time when they are ON and the percentage saving is more i.e 15% for 10% reduction in voltage.

Case Study 5 : Voltage optimisation for lighting through AVR

(i) Existing Average voltage level in daytime (10 hrs)= 230 V

Proposed voltage = 210 VExpected saving = 8.0%Total approx. lighting load = 25 kWExpected saving = 25 x 0.08

= 2 kWAnnual power saving = 2 kW x 10 hrs.x 300

= 6000 kWhAnnual monetary saving @ Rs 4.09 per kWh = Rs 24540

(ii) Existing avg. voltage level in off peak hrs = 240 V (14 hrs) Proposed voltage = 210 VExpected saving = around 9%Total lighting load in off peak hrs = 125 kWExpected saving = 125 kW x 0.09

= 11.25 kWAnnual power saving = 11.25 x 14 hrs. x 365 days

= 57487 kWhAnnual monetary savings = 57487 x 4.09

@ Rs 4.09 per kWh = Rs 2,35,122

Energy savings

Net Annual saving potential = Rs. 235122+Rs. 24540= Rs. 259662.00Net investment in providing AVR = Rs. 190000Payback Period = 9 months

6.6 Energy Saving Opportunities in LPG Pumps

LPG pumps consume around 14-15% power of the total plant consumption. These pumps run continuously for 16 hours per day. Other pumps are service water pump, bore well pump, fire-fighting pumps, which are run as per requirement in the plant.

The filling rate at carousel varies depending upon the number of cylinders filled in the LPG bottling plant. This is controlled through return line (bypass) and is operated based on pressure in the header. The system operating with throttled valves or operated with bypass valves in partially open condition, leads to the wastage of significant energy. This wastage of energy can be eliminated / minimized by the following methods:

• By installing proper size pump• By trimming the impeller of the pump• By changing the speed of the pump through VSD

In the present system, the requirement of flow is not constant and it varies as per the filling rate and bullet pressure. Keeping this operational constraint in view, flow reduction through changing the speed of the pump by installing VSD with feedback from discharge pressure/ flow will be the best option to minimize the energy wastage.

255254

Case Study 6 : Installation of Variable Speed Drive (VSD)

Brief

For a typical bottling plant having one carousel, 1 pump having 50 kW motor and 396m head / 150 m per hour discharge is required to pump LPG from the storage

tank to the carousel. Energy can be saved by closing the bypass valve on the return line and installing VSD on the motor of the pump to get the desired flow and Pressure at the carousel.

Energy Savings

- Present power consumption by pump - 40 kW2- Pump suction pr. - 5-6 kg/cm

2- Pump discharge pr. - 10 - 12 kg/cm- Expected power consumption by pump with VFD - 30 kW- Saving in power consumption - 10 kW- Annual operating - 4200 hrs- Annual Savings in kWh - 42000 kWh- Annual savings @ Rs 3.675 per kWh - Rs 1,54,350- Investment required for VSD & - Rs 5,00,000

automation (for pressure transmitter, cable) - Payback period - 39 months

6.7 Energy Conservation in Lighting

Significant amount of energy is consumed in Lighting application in a bottling plant due to operation during the night and also security requirement in very large areas. The following saving opportunities exist in the lighting system in a LPG bottling plant -

Case Study 7 : Replacement of 96 T/Ls of 40 W (T12) (having electromagneticchokes) operating in plant with 28W( T5) tubelights.

Brief

These are operated on an average for 12 hrs per day for 300 days in a year. the electromagnetic chokes in itself consume about 13W per tube light.

Energy Savings

Total energy consumption by 96 nos. 40-Watt = 96x (40 +13)x 300x 12tube lights with Electromagnetic chokes for 12 hrs as mentioned above = 18316 kWh/year

Total energy consumption by 96 nos.28 W(T5) = 96x28x300x12tube lights = 9677 kWh/year

So, total energy saving = 8639 kWh/yearMonetary saving potential at Rs 4.09/ kWh = Rs 35333/year Total investment@ Rs 500 per tube light = Rs 48000Pay back period = 7 months

Case Study 8 : Replacing HPMV Lamp fittings with metal Halide fittings

Brief

About 186 nos of 125 W HPMV lamp fittings in various sheds can be replaced by 70 W Metal halide fittings in a phased manner whenever any of the items of luminary goes out of order.

Energy Savings

Total energy consumption by 186nos, 125W HPMV = 186 x 125 x12x300 fittings, when operated for 12 hours for 300 days. = 83700 kWh/year

Total energy consumption by 186 nos. 70WMetal Halide fittings = 186x 70 x 12 x 300

= 46872 kWh/yearTotal kWh saving per annum = 36828 kWhMonetary saving potential at Rs 4.09/ kWh = Rs 150636/yearTotal investment@ Rs 1000 per light = Rs 186000.00Pay back period = 15 months

6.8 Energy Conservation Opportunity in LPG Compressor

Contribution of LPG Compressor in the energy consumption pattern of a LPG Bottling Plant is significant. LPG compressor is essentially a reciprocating compressor like air compressor and the saving potential in air compressor more or less holds good for LPG compressors as well, except leakage. Thus, volumetric efficiency assessment and corrective action thereof, happens to be a major energy saving opportunity in LPG compressors.

Operating practices contribute a lot to energy consumption. The higher the specific pressure ratio, the higher is the energy consumption. Thus, the endeavour should be to keep the specific pressure ratio as low as possible.

In actual practice, discharge pressure of LPG compressor is made higher for increasing bottling output or for hastening the process of LPG loading/ decantation. However, all these practices have implication on Energy consumption.

6.9 Other Energy Conservation opportunities

1) Use energy efficient lamps and replace incandescent bulbs with Compact Fluorescent Lamp (CFL).

2) Use task lighting, as keeping the light source as close as possible to the work place; as the light intensity decreases exponentially as the distance from the light source to the task increases.

23) Provide reflectors on the tube lights to enhance lumens/m (LUX), always keep reflector clean.

4) Make effective use of daylight wherever possible.5) Clean luminaries to increase illumination, normally 10 to 20 % light output

reduces over a period of six months if not cleaned. 6) Improve colour & reflectivity of walls, ceilings to reduce lighting energy needs.7) Whenever replacing a burnt out lamp, attempt should be made to replace it with

a more efficient lamp and the ordinary T/L fitting with an electronic ballast fitting.

256

Electronic ballast consumes only 2 Watts in comparison to the electromagnetic ballast which consumes around 13 Watts of electrical energy.

8) Use time clocks or daylight sensor control for outdoor lighting.9) Train personnel to switch off the light whenever not required, posters as

reminders can be placed on the doors for this purpose.10) Wherever LUX level is specified, it must be counter checked by LUX meter.11) During breaks, the lights of a specific workplace should be switched off, for

which individual switches hanging at the worktable shall be helpful.12) Interlocking of chain conveyor with cylinder washing pump.13) Avoiding idle running of pump conveyor system.

References

1. PCRA Energy Audit Report, HPCL LPG Bottling Plant, Asauda Bahadurgarh (Haryana), December, 2006

2. PPAC Ready Reckoner, Information as on 1.4.2008, Petroleum Planning & Analysis Cell, MOP&NG, GOI New Delhi

3. Teri Energy Data Directory & yearbook 2007, TERI Press, New Delhi4. World Energy Outlook, 2007, IEA Publication, Paris, France5. Basic Statistics on Indian Petroleum & Natural Gas, 2006-07, Ministry of

Petroleum & Natural Gas, (Economic Division), GOI

257

7.1 Introduction

The biggest challenge in the complete supply chain of Petroleum Products is to reach out to almost-37000 retail outlets all over the country. Every element in this value chain has to have unfailing reliability in all circumstances. Building this reliability in the logistics is a marvel of supply chain management.

The products from refinery are transported to the secondary points called Depots and Terminals through pipelines / wagons / tank trucks. The basic jobs undertaken at these depots / terminals is warehousing, wherein receipt, storage and dispatch of various products is accomplished. These secondary supply points are responsible for maintaining supply lines to Retail Outlets and numerous Institutional Customers.

Terminals/Depots mainly undertake pumping operations. Any energy conservation initiative in Depots/Terminals should aim at improving energy efficiency in pumping operations. PCRA has found energy conservation potential of upto 30% in Depots/Terminals operation.

A Depot/Terminal uses the following energy intensive machinery for accomplishing its operations:-

1. Pumps2. DG Sets3. Lighting4. Air Conditioners5. Miscellaneous Machinery

7.2 Energy Conservation Opportunities

The major energy conservation opportunities, identified by PCRA, during its various energy audit studies are as per the following details:

7.2.1 Pumping System

From Energy Conservation point of view, the area of concern in a terminal / depot operation is over sizing. The typical protocols for handling the problem of over sizing in pumping operation needs to be customized to the terminal operation, as the flow requirement here may vary over a wide range.

At the terminal, the number of bays operating at any particular instance is changing as a result of the change of flow requirement. Recirculation is the method of Capacity Control on Pumps being employed at present. In this method, a part of the product being pumped is recirculated back to the suction of the pump, to regulate the flow of the loading terminals/ bays. This type of control is the most energy inefficient, since only a part of the actual energy being consumed is useful and the rest is lost in re-circulation.

Marketing Terminals/ Depots

Chapter - 7

259258

The average working hours of the pumps observed at one of the terminals is as follows:

SKO Pump- 5 hrs per day with 1 to 3 bays operating at a time (1500 hrs/annum)

MS Pump - 3 hrs per day with 1 to 2 bays operating at a time (900 hrs/annum)

HSD Pump- 5 hrs per day with 1 to 3 bays operating at a time (1500 hrs/annum)

From each bay, one tank lorry is filled

Case Study 1 : Installation of Variable Frequency Drive (VFD) on HSD Pump

Brief

In order to eliminate / minimize the continuous Power losses in these systems, it is suggested to install a variable frequency drive (VFD) on the Pumps. This would enable the plant to control the flow through a feedback signal to the pump and vary the RPM to exactly match the requirement.

With the installation of a Variable Frequency Drive, energy savings could be achieved by reducing the RPM of the pump and the subsequent reduction in the power consumption per litre of material actually delivered.

Energy Savings

(i) Variable Frequency Drive (VFD) for HSD Pump of rated flow 2400 LPM

Energy Savings

ØEnergy Savings per annum = 13500/0.93 = 14516 kVAh

ØMonetary Savings per annum =Rs 0.486Lacs (@Rs 3.35 per kVAh)

ØEstimated Investments =Rs 1.3 Lacs

ØPayback period =33 months

Power Drawn in kW (measured values)

Material Operation Effective Flow after bypass –

LPM

At present (with by pass open)

After installing VFD

Net reduction in the power drawn in kW

Estimated working hours of the Pumps per annum

Estimated energy savings kWh

HSD

If 1 bay in use

825 (34.3% of 2400)

11.6 3.6 8.0 1500 12000

HSD

If 2 bays are in use

1250 (52.08% of 2400)

14

4.0

10.0

1500

15000

Avg 13500

(ii) Variable Frequency Drive (VFD) for SKO Pump

In case of SKO (40 HP motor), the savings shall be on the same lines

• Total Energy Saving per annum 14000/0.93=15053 kVAh

• Annual Savings Rs 0.504 Lakhs (@Rs 3.35 per kVAh)

• Estimated Investments Rs 1.5 Lakhs

• Payback period 36 months

Energy Savings

(iii) Operation by closing the bypass valve : By simply closing the return valve on the recirculation line, savings can be achieved.

Average kW saving observed in HSD, MS & SKO Pumps = 3 kW eachExpected annual running hrs of HSD and SKO Pumps = 1500 x2 =3000hrs Average annual energy saving in HSD and SKO Pumps = 9000 kWhExpected annual running hrs of MS Pump = 900hrsAverage annual energy saving in MS Pump = 2700 kWhTotal annual energy saving in HSD, MS & SKO Pumps = 11700 kWh

• Total Energy Savings per annum 11700/0.93=12581 kVAh

• Annual Savings Rs 42146 (@Rs 3.35 per kVAh)

• Estimated Investments Nil

• Payback period Immediate

When, no receipt of the product is taking place at TLF area and the pump is run with bypass closed, only churning of the product takes place; the pump being centrifugal shall be able to bear the backpressure. In spite of this, the operator should take care to avoid prolonged idle running of the pump

7.2.2 Illumination

Illumination in Depot / Terminal is basically required for safety reasons. Receipt operation is conducted during the night in locations receiving supply through Railway Wagons / Pipelines. However, illumination in the tank lorry filling Area, tank farm area and the buffer area is provided through flame proof lighting fixtures. The lighting is predominantly through high mast towers.

The following case study has been taken from the actual study taken up by PCRA.

261260

Case study 2 : Replacement of 40W Tubelights having electromagnetic chokes by 36W T/L with Electronic chokes, assuming 0.8 as load factor

Energy Savings

Case Study 3 : Replacement of 40W tubelights with electromagnetic chokesby 28W T/L (T5), assuming 0.8 as load factor:

Energy Savings

Total energy consumption by 131 nos. 40 Watt = (40+15)x 131 x 0.8 tubelights with electromagnetic chokes, = 5.76 kWtaking working hours (12 hrs daily in 300 days). = 3600 hrs

= 20736 kWh/year

Total energy consumption by 131 nos. 28 Watt = (28) x 131x 0.8 x 3600 tubelights (T5), taking working hours = 10564 kWh/year (12 hrs daily in 300 days).

So, total energy saving = 10172 kWh/yeartaking pf as 0.82 = 12405 kVAh /yearmonetary saving potential = Rs 44,286.00/year

(@ Rs 3.57/kVAh)

Total investment @ Rs.700/- per retrofit = Rs.91700.00

Payback period = 25 months

=

= (40+15)x 131 x 0.8 /1000

5.76 kW

=

3600 hrs

Total energy consumption by 131 nos. 40 Watt Tubelights with electromagnetic chokes, taking working hours (12 hrs daily in 300 days).

=

20736 kWh/year

=

(36 + 2) x 131x 0.8 x 3600

Total energy consumption by 131 nos. 36 Watt tubelights with electronic chokes, taking working hours (12 hrs daily in 300 days). = 14337 kWh/year

So, total energy saving taking pf as 0.82

= =

6399 kWh/year 7804 kVAh /year

monetary saving potential

=

Rs 27, 860.00/year (@ Rs 3.57/kVAh)

Total investment @ Rs.400/- per choke

=

400 x 131 = Rs.52400.00

Payback period = 23 months

Case Study 4 : Replacement of 100W Incandescent lamps by 15W Compact Florescent lamps (CFL), assuming 0.8 as load factor:

Energy Savings

Total energy consumption by 77 nos. 100 Watt = (100)x 77 x 0.8 incandescent lamps, taking working hours = 6.16 kW(12 hrs daily in 300 days). = 3600 hrs

= 22176 kWh/yearTotal energy consumption by 77 nos. 15 Watt CFL = (15) x 77x 0.8 x 3600lamps, taking working hours (12 hrs daily in 300 days). = 3326 kWh/yearSo, total energy saving = 18850 kWh/yeartaking pf as 1.0 = 18850 kVAh /yearmonetary saving potential = Rs 67294.00/year

(@ Rs 3.57/kVAhTotal investment = Rs 11,000Payback period = 2 months

Case study 5 : Installing daylight sensor for controlling street lights and out side lights, thereby saving 1hour of daily running, assuming 0.8 as load factor

Energy Savings

Total energy consumption by 43 nos 250W sodium = (43x250 + 54x400 +vapour lamps, 54 no 400W Sodium vapour = 10x250 + 42x160) xlamp, 10 no 250W Mercury Vap lamp and 42 0.8 no 160W Mercury Vap Lamp , taking working = 33.26 kWhours (1 hrs daily in 365 days). = 365 hrs

= 12138 kWh/year

So, total energy saving, taking pf as 0.82 = 14802 kVAh/yearMonetary saving potential = Rs 52843.00/year

(@ Rs 3.57/kVAh

Total investment = Rs 5,000

Payback period = 2 months

7.2.3 Energy Saving Opportunity in DG Sets

The loading of the DG set as shown in the Figure- 7.1, significantly influences the fuel efficiency of a DG set. The associated losses due to operation of the DG set below the optimum limit is reflected by significant increase in the specific fuel consumption. As can be seen from the curve, the generator should be loaded between 65% to 85%. The loading beyond 85% does not give any extra efficiency, but it decreases engine life.

263262

Figure - 7.1 Load Characteristics of DG Set

It is generally observed, that keeping the security lights on during nights is a security requirement. To keep the lights on, DG set is operated in case of power failure. It is further observed that if only lighting load is served by the DG set, the DG set becomes under loaded and hence the specific generation ratio of the DG set goes down drastically.

It is suggested to have a smaller DG set to take care of lighting load only during nights.

Case Study 6 : Improving the efficiency by overhauling of DG Sets

The specific power generation of two no. DG sets available in a terminal was assessed as per the following details :

Equipment Specific Power Generation Remarks(kWh/liter of fuel oil)

DG Set. - 1 (200 kVA) 2.9 At 41% of rated loadDG Set. - 2 (75 kVA) 2.5 At 51% of rated load

The specific power generation of both the DG sets is very low, normally it should be > 3.8 units per litre of HSD. As can be seen from the table, the performance of 200 kVA DG set as compared with 75 kVA DG set is better.

Corrective measure in the form of major overhauling was undertaken. This resulted in improvement of specific power generation. The yearly consumption could be reduced from 17 kl per year to 11.75 kl per year resulting in savings of 5.25 kl HSD worth Rs. 17,0000/- per year.

Monitoring of specific power generation and early detection of deviation would help decide when to conduct major overhaul.

Major overhaul may include :

(I) Calibration of fuel injection system(ii) Setting of fuel discharge pattern(iii) Removal of hot spots(iv) Reduction of blow-by(v) Replacement of cylinder liner/piston rings etc.

0

100

200

300

400

500

600

700

10 20 30 40 50 60 70 80 90 100

% Rated Load

I nefficient range Efficient range

Fue

l C

onsu

mpt

ion

kwh/

litr

e of

oil

DG sets - Other recommendations:

(i) The DG set should be maintained properly and loading should be monitored so as to achieve specific power generation of 3.80 units per litre,

(ii) Energy meters may be installed in the DG panels, to enable the plant to monitor specific power generation of each of the DG set on regular basis.

(iii) It should be ensured that the single phase loads on the DG set should be distributed appropriately so that the unbalance between the 3 phases is not more than 10% of the total DG set capacity.

(iv) The lube oil consumption should not exceed 1% of fuel consumption.

(v) DG room should be properly ventilated to achieve best results. The allowable 0temperature of inlet air is ambient ±5 C. Arrangements should be made to

0maintain required inlet air temperature, because for every 3 C rise in inlet air temperature, there is 1% loss of fuel.

7.2.4 Optimization of Power Supply System Billing and Demand Side Management

The Energy conservation opportunities mentioned above in the Bottling Plant section under the following heads hold good for terminal / depots as well:

a) Transformers b) Demand Side Managementc) Maximum Demand Control / PF Controld) Voltage Optimization

References :

1. PCRA Energy Audit Report, IOCL Jodhpur Terminal, Jodhpur (Rajasthan), August, 2006.

2. PCRA Energy Audit Report, IOCL Najibabad Depot, Najibabad (UP), September, 2005.

3. PCRA Energy Audit Report, HPCL Mathura Terminal, Mathura (UP), April, 2007.

4. PPAC Ready Reckoner, Information as on 1.4.2008, Petroleum Planning & Analysis Cell, MOP&NG, GOI New Delhi

5. Teri Energy Data Directory & yearbook 2007, TERI Press, New Delhi

6. World Energy Outlook, 2007, IEA Publication, Paris, France

7. Basic Statistics on Indian Petroleum & Natural Gas, 2006-07, Ministry of Petroleum & Natural Gas, (Economic Division), GOI

ØChapter - 8 Power GenerationØChapter - 9 Iron and SteelØChapter - 10 FertilizersØChapter - 11 Pulp and PaperØChapter - 12 CementØChapter - 13 SugarØChapter - 14 Aluminum

Section 4Energy Conservation

in other Industry sectors

267

Thermal Coal Gas Diesel Total

Nuclear

Hydro

Wind & Other Renewables

GrandTotal

76299 14656 1202 92157 4120 35908 11125 143311

8.1 Overview

Availability of quality and affordable power is one of the driving force for industrial development. India is still lagging behind in terms of availability of quality, uninterrupted, clean and affordable power. Available power cannot meet the demand because of which the country experiences a perennial shortage of power.

However, scenario of high power demand may change significantly as a result of implementation of energy efficiency measures across various sectors.

8.2 Installed capacity

The total installed capacity under the utilities in India increased to 143 GW (as on th st30 April 2008) from 132 GW (as on 31 March 2007) representing an increase of

8.3%.

thTable - 8.1: Installed Capacity As On 30 April, 2008 (in MW)

Source: CEA

8.3 Generation

The overall electricity generation in the country, which was 532.69 BU (Billion Units i.e. Billion kWh) in 2002-03, has risen to 704.451 BU in 2007-08. The increase over last year is 6.83%. The all India PLF (plant load factor) of thermal utilities during 2007-08 was 78.61% as compared to 76.8% in 2006-07.

8.4 Power supply position

The country experienced an overall power shortage of 9.6% and peaking power shortage of 13.8% in 2006-07. The situation deteriorated further in 2007-08, with supply and peaking deficit rising to 9.8% and 16.6% respectively.

8.5 Potential For Energy Saving

Power cannot be generated; only converted from one form to another; what is implied is the generation of some useful power at the expense of some other less-convenient power. Power generation efficiency can be defined as "useful output power divided by input power", but it is not rigorous enough since at least two choices exist for the evaluation of input power: a) heat-equivalent power, and b) work-equivalent power. Table 8.2 presents typical values of power generation efficiencies using the raw input power, the most commonly used, although the net input power criterion, i.e. the energy or available energy of the raw energy source, gives a more sound measure of the 'technological efficiency' of the power plant.

Chapter - 8

Power Generation

269268

Energy source Typical

efficiency

[%]

Typical range

[%]

Photovoltaic 10 5-15Solar thermal 15 10-25Gas turbine 30 15-38Spark Ignition I.C. Engine 30 25-35 Nuclear 33 32-35Steam turbine 33 25-39Wind turbine 40 30-50Compression Ignition I.C. Engine

40 35-49

Fuel cell 45 40-70Combined GT -ST 50 45-60Hydro electrical 85 70-90

Table - 8.2: Power Generation Efficiencies

The consumption of electricity by power plant auxiliaries and the efficiency of the plants depend on factors such as unit size, level of technology, plant load factor, fuel quality etc.

The auxiliary consumption in general varies between 3 to 6% for larger plants and close to 10% for smaller captive power plants. Moreover, PCRA studies indicate that the Energy savings in small size power plants varies between 6 - 10% of auxiliary consumption.

The overall efficiencies of power plants with sub critical parameters fall in the range of 35 - 39%, which can be improved to 45% using supercritical parameters with conventional steam turbines. Using combined cycle mode, the maximum efficiency can reach upto 50%.

Power plants are adopting several latest technologies to improve the efficiency and operating practices. Some of the power plants are installed with multifuel capabilities by design for flexibility to use different fuels depending on availability and price and also to address environmental issues like NOx and SOx reduction.

The National Energy Map for India "Technology Vision 2030" report has identified the following, as the preferred power generation technologies:

(1) Large Hydro

(2) Refinery-residue-based IGCC (integrated gasification combined cycle)

(3) Imported-coal based IGCC

(4) High-efficiency CCGT (combined cycle gas turbine) (H-frame gas turbine)

(5) Indigenous-coal-based IGCC

(6) Normal CCGT

(7) Ultra - Supercritical boiler

(8) Supercritical boiler

(9) Nuclear Fast Breeder Reactor based Power Plants.

Some of these latest technologies and measures available for efficiency improvement are briefly described as under:

8. 5.1 Super Critical Power Plants

New pulverized coal combustion systems utilizing supercritical and ultra-supercritical technology, operate at increasingly higher temperatures and pressures and consequently achieve higher efficiencies than conventional PCF (Pulverized Coal Fluidized) units and results in significant CO reduction. Supercritical steam 2

cycle technology has been used for decades and is becoming the system of choice for new commercial coal-fired plants in many countries. Recent plants built in Europe and Asia use supercritical boiler-turbine technology and China has made this standard on all new plants of capacity 600 MWe and upward.

Case Study 1: Comparison between conventional process and supercritical pressure steam generation process

Conventional Process

21. Conventional steam pressure is around 170 kg/cm .

2. From the Rankine cycle T-S diagram it has been known that the higher steam pressure & temperature produces the higher thermal efficiency, but it has not been put into practice due to the technological limitation in designing boilers and turbines.

New Process

1. In the new process, the steam pressure is raised to a super critical region2 (higher than 246 kg/cm ), increasing thermal efficiency.

2. Consequently, the boiling of water to generate steam does not occur in theboiler drum. As the water in the liquid phase directly shifts to the vapor phase,therefore once - through boiler is required instead of the drum type boiler.

3. High temperature strength under high pressure was the problem confronting the designing of the super heater, reheater, main steam valve and turbine blades, etc. However, as high-temperature materials have become available economically of late, the supercritical pressure generation isnow being widely adopted.

24. When the steam pressure is excessively high (300 kg/cm or higher), the gross thermal efficiency does not increase much due to the increase of power consumption by the feed water pump.

271270

Process Comparison

Source: World Coal Institute

Source: Japan Energy Conservation Directory

8.5.2 Ultra Supercritical (USC) Power Plants

There's nothing “critical” about supercritical. “Supercritical” is a thermodynamic expression describing the state of a substance where there is no clear distinction between the liquid and the gaseous phase (i.e. they are a homogenous fluid). Water reaches this state at a pressure above 221 megapascals (MPa).

The “efficiency” of the thermodynamic process of a coal-fired power plant describes how much of the energy that is fed into the cycle is converted into electrical energy. The greater the output of electrical energy for a given amount of energy input, the higher the efficiency. If the energy input to the cycle is kept constant, selecting elevated pressures and temperatures for the water-steam cycle can increase the output. Power plants operating at supercritical steam pressures are termed as “Supercritical” power plants.

Supercritical power plants, due to their higher efficiencies, have significantly lower emissions of pollutants such as fly ash and Oxides of Sulphur and Nitrogen than sub-critical plants for a given power output.

Table – 8.3: Average Efficiency Levels at Pulverised Coal-fired Power Plants

Process New Process Conventional Process

Facility cost

Steam Pressure 2More than 246 kg/cm 2169 kg/cmSteam temperature 0600/560 C

0560/540 CTurbine High pressure in 11 steps

Medium pressure in 6 steps.High pressure in 9 steps Medium pressure in 6 steps.

Medium pressure rotor blade

Ni-Cr-Mc-Ti heat resistant alloy steel.

12% Cr-Mc-V alloy steel

Pressure Strength Each unit of the boiler, highpressure feed water heater pumps needs to be made high pressure resistant.

Minimum load 15% - 25% 15%Change of load Fast response Ordinary responseFrequent starts and stops

Suited Suited

Starting-up loads Ordinary OrdinaryStart and StopThermal efficiency

1.5 times higher for the 246 2kg/cm class.

Takes a long time Ordinary1-2% higher

- Standard.

Plant

Average efficiency levels %

Low efficiency High efficiency

Super critical Ultra-Supercritical

29 39 Up to 46 55

2Up to an operating pressure of around 194 kg/cm in the evaporator part of the boiler, the cycle is sub-critical. This means, that there is a non-homogeneous mixture of water and steam in the evaporator part of the boiler. In this case, a drum-type boiler is used because the steam needs to be separated from water in the drum of the boiler before it is superheated and led into the turbine. Above an operating

2pressure of 225 kg/cm in the evaporator part of the boiler, the cycle is supercritical. The cycle medium is a single-phase fluid with homogeneous properties and there is no need to separate steam from water in a drum. Once-through boilers are therefore used in supercritical cycles.

The traditional coal-fired power plants are marked with emissions of environmentally damaging gases such as CO , NOx and SOx at alarmingly high 2

levels. Adoption of Ultra Supercritical (USC) power plants with increased steam temperatures and pressures significantly improves efficiency, reducing fuel consumption and environmental emissions by a commensurate degree. Increase of

o osteam parameters from around 180 bar and 540 C-560 C to ultra supercritical ocondition of 300 bar and 600 C have led to efficiency increases from around 40% in

1980 to 43-47% in 2006. A further enhancement of thermal efficiency may be obtained by combining an advanced steam cycle plant with a gas turbine; in this way efficiencies of over 60% are possible.

8.5.3 New Generation Gas Turbines

For years, gas turbine manufacturers faced a barrier, that for all practical purposes, capped power generating efficiencies for turbine-based power generating systems.

oThe barrier was heat. Above 1260 C, the scorching heat of combustion gases caused metals in the turbine blades and in other internal components to begin degrading. Since higher temperatures are the key to higher efficiencies, this effectively limited the generating efficiency at which a turbine power plant could convert fuel into electricity.

The US Department of Energy's Fossil Energy department took on the challenge of turbine temperatures in 1992 and nine years later, two of its private sector partners produced "breakthrough" turbine systems that pushed firing temperatures to

o1426 C and permitted combined cycle efficiencies that surpassed the 60 % mark - the "four-minute mile" of turbine technology.

Moreover, the advanced turbines achieved the higher firing temperatures while actually reducing the amount of nitrogen oxides formed to less than 10 parts per million (NOx is a product of high temperature combustion).

Among the innovations that emerged from the Department's Advanced Turbine Systems program were single-crystal turbine blades and thermal barrier coatings that could withstand the high inlet temperatures, along with new firing techniques to stabilize combustion and minimize nitrogen oxide formation.

H Series Turbines: 60% Efficient

The H System of GE Power Systems was the first turbine to surpass the 60% efficiency threshold, nearly five percentage points better than the prior best available system, in an industry where improvements are typically measured in tenths of a percent.

273272

G Series Gas Turbines: 58% Efficient

The Siemens Westinghouse engine has demonstrated a net efficiency of approximately 58 percent in combined cycle application.

Case Study 2: Surface temperature measurement of steam distribution network at a Gas Turbine Power Station

Brief

Insulation break in the networking of the steam pipeline and other appliances leads to the loss of power production through Heat Recovery Steam turbine Generators (HRSG).

At a Gas Turbine Power Station there are three steam turbines each of capacity 34 MW. Exhaust gases of gas turbine is used to produce steam, which is at temperature

Oof 510 C. The superheated steam from HRSG is sent to steam turbine to produce power and condensate sent to the condenser. In condenser the temp is dropped from

0125 to 56 C, which is sent to Deaerator. This condensate is again sent to HRSG for Steam Generation. Heat loss takes place from steam distribution network components and is a direct loss of power.

Energy savings

Sr. Description HRSG-3 HRSG-5 HRSG-6 1

Total length of insulation break (m) 0.25 0.55 0.50

2 Total area of insulation break/improvement Required (m

2) 0.471 1.036 0.942

3 Heat Loss Coefficient (kCal/M

2/hr) 1805.17 4149.52 3663.50

4 Total Heat Loss (kCal/hr) 850.24 4299.73 3451.02 5 Steam Flow Rate in

Pipeline (T/hr) 53.94 56.86 50.1 6 Total Heat Flow in the

Pipeline(kCal/hr x 106) 187.6 198.0 173.5

7 Heat Loss% 0.0010 0.0021 0.0021 STG-2 STG-3 8 Electrical Efficiency of

STG 13.59 8.20 9 kCal/kWh consumption by

STG 6328.18 10487.8 10 Heat loss, kCal /hr 850.24 7750.75 11 KWH Loss due to

insulation brake 0.134357 0.739025 12 Working Hrs 694 582 13 kWh Saving per Month 93.2 430.1 14 kWh Saving per Annum 1118.9 5161.3 15 Rs/kWh 2.23 2.23 16 Annual saving in Rs 2495.20 11509.81

8.20

STG-3

8.20

10487.8

7750.75

0.739025

582

5161.3

430.1

11509.81

2.23

kWh Loss due tobreak

Annual savings : Rs 14000 per yearInvestment required : Rs 25000Payback period : 22 months

8.5.4 IGCC Technology (Integrated Gasification Combined Cycle)

An alternative to achieve efficiency improvements in conventional pulverized coal fired power stations is through the use of gasification technology. IGCC plants use a gasifier to convert coal (or other carbon-based materials) to Syngas, which drives a combined cycle turbine. IGCC technology, using coal gasification, allows the environmental benefits of a natural gas fueled plant and the thermal performance of a combined cycle.

Coal is combined with oxygen and steam in the gasifier to produce the Syngas, which is mainly H and carbon monoxide (CO). The gas is then cleaned to remove 2

impurities, such as sulphur and the Syngas is used in a gas turbine to produce electricity. Waste heat from the gas turbine is recovered to create steam, which drives a steam turbine, producing more electricity – hence, a combined cycle system.

Case Study 3: Substitution of LDO By Coal Gasification in thermal power plant

Brief

Energy savings

Avg. expenses on the LDO are about = Rs 6, 01,942 per dayExpenses on equivalent coal is = Rs 3,02,674 per dayThus, saving of about Rs 2,99,267 per day is achieved.Annual savings : Rs 109 Million Investment required : Rs 30 MillionPayback period : 4 months

8.5.5 High efficiency steam turbine blade

A steam turbine that provides a high thermal efficiency by adopting the latest blade design theories, such as the laminar flow blade (Shrinked blade) with the cross-section of the blade designed to cause the least turbulence to the steam flow, a nozzle with its tip twisted in consideration of the effect of the outer and inner walls on the tip and the root of the blade (controlled vortex nozzle) and the multiple fin sealing designed to prevent steam leak from the tip of the blade.

Before Improvement After ImprovementA thermal power station does not have buffer stock of coal for its boiler and therefore the temperature of the furnace goes down. This problem is presently solved by firing LDO, which is a costly proposition in view of increasing cost. Substitution of LDO by the Producer Gas can reduce cost incurred on LDO.

Producer gas, with a calorific value 3of 1100 kcal/m is generated in

indigenously designed plant. Producer 0 gas at about 350 C is then led to

use point, which can be 50-150 m away.

275274

Case Study 4: High efficiency steam turbine blade

Brief

Internal heat efficiency of a 500,000 kW-class high-technology steam turbine is2 - 2.5% (relative value) better than the conventional type. With the utilization rate of 38%, energy saving is 3,500 kL/y in crude oil equivalent.

Energy savings

Annual savings : Rs 80 Million Investment required : Rs 160 MillionPayback period : 2 years

8.5.6 Nuclear Power Generation

The use of nuclear power for electricity generation commenced about 50 years ago in India. Today, nuclear power produces 3% of the country's total energy generation. Expanding nuclear power is thus a matter of continuation of National strategies. More countries are embracing nuclear power as a part of their energy mix and as their Global environmental responsibility.

8.5.6.1 Three Stage Nuclear Power Programme

The total energy content in the current known Indian nuclear resources is at least twenty times more than that of other non-renewable resources. With a view to utilize this huge resource for electricity generation, Department of Atomic Energy (DAE) has been working on a three-stage nuclear power programme based upon closed fuel cycle. The three stages need to be executed sequentially.

The three stages are:

• Natural uranium fuelled Pressurized Heavy Water Reactors (PHWRs)• Fast Breeder Reactors (FBRs) utilizing plutonium based fuel• Advanced nuclear power systems for utilization of thorium

stWork on the 1 stage is already on progress. The current Indian nuclear energy 235 238resource consists of 61,000 tonnes of Uranium (U & U ) and more than 225,000

232tonnes of thorium (T ). The Indian Nuclear power programme is based on closed nuclear fuel cycle, in which the spent fuel of the first stage

(PHWR) is reprocessed to obtain fissionable Plutonium.

Table - 8.4: Three stages in Indian Nuclear Power Programme

Source : Department of Atomic Energy

Pressurised Heavy Water Reactors

-30 kWth Operational- -300 MWe under development-Power potential is very large

-15 unitsoperating.-3 units under construction-Scaling to 700 MWe-Power potential 10GWe

-Operational since 1985-Technology realised.-40 MWth FBTR are in operation-500 MWe PFBR under construction-Power potential 530 GWe

STAGE-I PHWRs

STAGE-IIFBRs

STAGE-III

TBRs

The first stage comprising setting up of PHWRs and associated fuel cycle facilities is already in the industrial domain. The technology for the manufacture of various components and equipment for PHWRs in India is now well established and has evolved through active collaboration between the DAE and the industry. Twelve PHWRs are operating and two more 220 MWe PHWRs and two PHWRs of 540 MWe rating are under construction. Construction of more such units is being planned. As DAE gains experience and masters various aspects of the nuclear technology, performance of nuclear power plants is continuously improving. Average capacity factor of nuclear power plants has steadily risen from 60% in 1995-96 to 82.5% in the year 2000-01.

The second stage envisages setting up of Fast Breeder Reactors (FBRs) backed by reprocessing plants and plutonium-based fuel fabrication plants. In order to expand the nuclear power capacity in the country, fast breeder reactors are necessary. For the second stager reactors, plutonium, due to its highest value of eta (the ratio of neutrons produced to neutrons absorbed) of all fissile materials, is used in the fast

ndbreeder reactors (FBR). The current Indian programme in the 2 stage starts with the well proven oxide fuel based FBRs and subsequently, at an appropriate stage, when all new necessary technologies have been developed & demonstrated, metallic fuel based FBRs will be introduced. A 40 MWt, Fast Breeder Test Reactor (FBTR) has been operating at Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam. FBTR has provided valuable experience with liquid metal Fast Breeder Reactor Technology and the confidence to embark upon construction of a 500 MWe Prototype Fast Breeder Reactor (PFBR). Detailed design, R&D and technology development of the PFBR is in advanced stage. Construction work on this is expected to start in a few months. This will also be located at Kalpakkam near Chennai.

The third stage will be based on the Thorium-uranium-233 cycle. Uranium-233 is obtained by irradiation of Thorium in PHWRs and FBRs. An Advanced Heavy Water Reactor (AHWR) is being developed at Bhabha Atomic Research Centre (BARC) to expedite transition to thorium-based systems. The reactor physics design of AHWR is tuned to generate about 75% power in Thorium, and to maintain negative void co-efficient of reactivity under all operating conditions.

8.5.7 Advanced Cogeneration Systems

Combined heat and power systems (CHP, also called cogeneration) generate electricity (and/or mechanical energy) and thermal energy in a single, integrated system. Conventional electricity generation is inherently inefficient, converting only about one third of a fuels potential energy into usable energy. Because CHP captures the heat that would otherwise be rejected in traditional generation of electric or mechanical energy, the total efficiency of these integrated systems is much greater than from separate systems. The significant increase in efficiency with CHP results in lower fuel consumption and reduced emissions compared with separate generation of heat and power. CHP is not a specific technology, but rather an application of technologies to meet end-user needs for heating and/or cooling, and mechanical and/or electric power. Steam turbines, gas turbines, combined cycles, and reciprocating engines are the major current technologies used for power generation and CHP. Some basic overview of specific end-use applications of CHPs in varying capacity is as under:

277276

Large scale (> 10 MW). Currently, most of the installed CHP plants have capacities over 20 MW. The future potential of large-scale conventional CHP systems is estimated at 48 GW. An increase in turbine-inlet temperature has led to increasing efficiencies in gas turbines. Industrial-sized turbines are available with efficiencies of 40 to 42%.

The higher inlet temperature also allows a higher outlet temperature. The flue gas of the turbine can then be used to heat a chemical reactor, if the outlet and reactor temperatures can be matched. One option is the so-called “re-powering” option. In this option, the furnace is not modified, but the combustion air fans in the furnace are replaced by a gas turbine. The exhaust gases still contain a considerable amount of oxygen, and can thus be used as combustion air for the furnaces. The gas turbine can deliver up to 20% of the furnace heat.

Another option, with a larger CHP potential and associated energy savings, is “high temperature CHP.” In this case, the flue gases of a CHP plant are used to heat the input of a furnace. High temperature CHP requires replacing the existing furnaces. This is due to the fact that the radiation heat transfer from gas turbine exhaust gases is much smaller than from combustion gases, due to their lower temperature.

The main difference is that, in the first type the process exhaust gases directly heat feed, where the second type uses thermal oil as an intermediate, leading to larger flexibility. In the first type, the exhaust heat of a gas turbine is led to a waste recovery furnace in which the process feed is heated. In the second type the exhaust heat is led to a waste heat oil heater in which thermal oil is heated. The heat content of the oil is transferred to the process feed. The second type is more reliable, because a thermal oil buffer can be included.

Medium scale (< 20 MW). Research aims at developing medium-scale gas turbines with high efficiencies. Current turbines of this size have efficiencies of around 25%.

Steam-injected gas turbines (STIG, or Cheng cycle) can absorb excess steam, e.g. generated due to seasonal reduced heating needs, to boost power production by injecting the steam in the turbine. Steam injection boosts the power output of the turbine. The size of typical STIGs starts around 5 MWe. Currently, over 100 STIGs are found around the world, especially in Japan as well as in Europe and the U.S. Many industrial sites have excess low-temperature waste heat that is currently not used due to a lack of suitable uses or due to poor economics.

Pressure recovery turbines are an opportunity to recover power from the decompression of natural gas or pressurised fluid lines on industrial sites. Recovery turbines can recover part of this energy by producing power.

Small scale (< 1 MW). For small scale industrial applications, the major developments are found in improved designs for reciprocating engines, fuel cells, micro turbines, and developments in integration of the unit in processes allowing more efficient operation (e.g. tri-generation of power, heat and cooling or drying and other direct process applications, see above). Micro-turbines and fuel cells are the most exciting developments in small-scale CHP technology.

Micro turbines (25- 500 kW) are expected to have an efficiency of 26-30%. Although this is lower than the efficiency of power generation in large grid

connected power plants, but their use in CHP unit can provide substantial energy savings.

Fuel cells generate direct current electricity and heat by combining fuel and oxygen in an electrochemical reaction. This technology is advancement in power generation that avoids the intermediate combustion step and boiling water associated with Rankine cycle technologies or efficiency losses associated with gas turbine technologies. Fuel to electricity conversion efficiencies can theoretically reach 80-83% for low temperature fuel cell stacks and 73-78% for high temperature stacks. In practice, efficiencies of 50-60% are achieved with hydrogen fuel cells while efficiencies of 42-65% are achievable with natural gas as a fuel. The main fuel cell types for industrial CHP applications are phosphoric acid (PAFC), molten carbonate (MCFC) and solid oxide (SOFC). Proton Exchange membrane (PEM) fuel cells are less suitable for cogeneration as they only produce hot water as byproduct. PAFC efficiencies are limited and the corrosive nature of the process reduces the economic attractiveness of the technology. Hence, MCFC and SOFC offer the most potential for industrial applications.

Although PAFC fuel cell system is most commercially developed, MCFC and SOFC offer the most potential in terms of efficiency. Stand-alone SOFCs have achieved efficiencies of 47%, and in combination with a gas turbine in a pressurized system, efficiencies of 53% (LHV) have been achieved. Unfortunately the production costs of SOFCs are still high. A comparison of different fuel cell technologies is given below in table no 8.5:

Table - 8.5: Comparison of different Fuel Cell Technologies

Source: www.fuelcellstoday.com

Case Study 5: Air cooler for gas turbine combustion air in a CHP plant

Brief

• An unvented type gas turbine has a characteristic that as intake-airtemperature rises, the output drops.

• This is the main cause of the power drop in summer time of a combined steamand gas turbine cycle power plant of a high thermal efficiency.

• As a countermeasure for it, an air cooler using a spray nozzle utilizing latentheat of water has been developed.

0• When the dry-bulb thermometer (DB) indicates 30 C and the wet-bulb0thermometer (WB) indicates 23.5 C, relative humidity (RH) is 60%.

• In this case, cooling by water injection is performed with humidifying effect.

,

Immobilized Liquid Phosphoric acid

Electrolyte

OperatingtemperatureEfficiencyTypical Electrical PowerPossible Applications

AFCPotassium hydroxide

o60-90 C

45-60%Up to 20kW

Submarines, spacecraft

DMFCPolymer membrane

o60-130 C

40%<10 kW

Portable applications

MCFCImmobilized Liquid Molten Carbonate

o650 C

45-60%>1 MW

Power stations

PAFC

o200 C

35-40%> 50 kW

Power stations

PEMFCIon Exchange membrane

o80 C

40-60%

Up to 250 kW

Vehicles. Smallstationary

SOFCCeramic

o1000 C

50-65%

> 200 kW

Power stations

279278

0 0As the result, DB temperature becomes 28.2 C and WB temperature, 23.5 C0respectively. The inlet temperature decreases by 1.5 C because of which the

output of gas turbine increases and thermal efficiency improves.

Energy savings

Increase of output from combined plant (at temperature 30°C, relative humidity 60%): 12,000 kW

Reduction equivalent to crude oil consumption: 23,328 kL/year

Case Study 6: Rotating regenerative air pre-heater automatic seal gap controller

Brief

A device to prevent air leakage in a rotating regenerative air preheater (hereafter referred to as A/H) adopted in a medium to large capacity boiler.

1) Air leakage occurs through the gap between the rotating part and thestationary part of the A/H toward the gas side (ordinarily about 10%).

2) The air leakage is caused by such factors as the radial seal at the high-temperature side, radial seal at the low temperature side, and post and axialseal entrainment (residual air in the heat conductive elements).

3) Air leakage from the radial seal at the high temperature side is the mostconspicuous, accounting for 40 - 50% of the total air leakage.

Energy savings

Annual savings : Rs.19.4 Million Investment required : Rs.15 Million Payback period : Less than12 months

8.5.8 Renovation & Modernization

Old power plants are modernized to keep up the operation of the equipment and its efficiencies. The advantages of Renovation & Modernization are:

i. Enhancement of operational efficiencyii. Improvement in Plant Load Factor (PLF)iii. Meeting stringent environmental pollution control standardsiv. Extend plant lifev. Capacity augmentation

Following renovation and retrofitting techniques are mostly adopted by power plants:

i. Steam turbine retrofitting (blades replacement and improvement of thelabryrinths' operation and turbine control system etc)

3,038.6kW 59.3kW

3,097.6kW

Forced draft power

Before installation

After installationReduction rate

Air leak rate

8.32%

6.19% 2.13%

Heat recovery

(Standard)

+903,000kcal/h96 liter/h (oil equivalent)

ii. Improvement of the fuel preparation and firing systemiii. Implementation of techniques for further reduction of the NOx emissionsiv. Improvement of particles collecting systemsv. Optimization of the existing fuel drying system or implementation of new

effective drying techniquesvi. Replacement, rearrangement or resizing of heat exchange surfacesvii. Supplementary heat exchange surfaces for further heat recovery from flue

gasviii. Improvement of air preheating system

Case Study 7: Operation method of increased temperature of main steam at boiler outlet

Brief

A method to improve thermal efficiency and to reduce fuel consumption by raising the temperature of the main steam at the boiler outlet to 561°C (previously 541°C)

Before improvement

The following are the previous operational condition of the boiler and turbine.Temperature of main steam at the boiler outlet: 541°CTemperature of main steam at the turbine inlet: 538°CVacuum of the condenser: 722mmHgGross thermal consumption rate: 2,208kcal/kWhThermal efficiency: 38.95%

2Secondary superheater heat transfer area: 390 mSecondary superheater tube material: SUS 321HTB

After improvement

1) Improvement of thermal efficiency by increasing the temperature of the mainsteam is evaluated by examining the T-S diagram of the Rankine cycle.

2) For increasing the temperature of the main steam, it is necessary to increasethe heat transfer area, for which space is needed.

3) At the same time, high temperature corrosion resistance of the heat transfer tube needs to be increased.

4) Based on the above examination, it was decided to raise the temperature of t h e

main steam to 561°C, and the following measures were implemented.

· Temperature of main steam at the boiler outlet: 561°C (increased by

20°C)

· Temperature of main steam at the turbine inlet: 556°C (increased by

18°C)2· Secondary superheater heat transfer area: 750 m (approx. twofold

increase)

· Secondary superheater tube material SUS 347HTB

5) The secondary superheating tube has been changed from the previous 1-loop

281280

Energy savings

The effect of this method applied to a 220,000 kW generation plant is shown below :

Annual savings(at an utilization rate of 30%) : Rs 25.52 Million Investment required : Rs 47.2 Million Payback period : 22 months

Case Study 8: Gas recirculating steam temperature control system

Brief

For the purpose of balancing the thermal absorption between the evaporation section of the boiler (mainly radiation heat in the furnace) and the superheating section for the steam (mainly convective heat transfer in the superheater, reheater, and the economizer), boiler exhaust gas at the economizer outlet is recirculated by the recirculation fan to the bottom of the furnace.

Energy savings

Annual savings (Boiler at 250MW class) : Rs 16 MillionInvestment required : Rs 20 Million Payback period : 16 months

8.5.9 Energy Efficiency Improvement through loss minimisation

The operation of the steam generator requires continuous surveillance. The heat losses from the steam generator can be categorised as:

Before replacement After replacementPreviously, the thermal absorption balance would tilt toward the superheating section, and when the temperature of the superheated steam was in excess of the designated value, spray water was injected into the superheated steam to lower the temperature(water spray steam temperature control system).

As the water spray method would lower the boiler efficiency, this method was not thermally efficient. Boiler efficiency is lowered by 1 - 1.5%. The thermal absorption balance depends on the kind of fuel used and changes by converting the fuel.

By the gas recirculation method, the amount of evaporated steam is decreased (or increased), and the temperature of the superheated steam goes up (or goes down), as the recirculation gas is increased (or decreased). As this adjustment is made easily by adjusting only the damper of the recirculation fan, it can be readily applied to various fuels such as heavy oil, crude oil, natural gas, etc.

Thermal efficiency

Improvement by 0.48% in both SH and RH

Power cost Saving of power for the recirculating fan equivalent to thermal efficiency of 0.02%

Total Improvement equivalent to thermal efficiency of 0.5% (converted in fuel cost)

Load Gross thermal consumption rate Thermal efficiency Improvement of thermal efficiency

220,000 kW (rated)2,195 kcal/kWh39.23%0.28%(absolute value)

Annual fuel savingApprox. 1,100 kL(At a utilization rate of 30%)

· Losses via the off-gas· Losses through unburnt fuel· Losses through unburnt material in the residues, such as carbon in bottom

and fly ash· Losses via the bottom and fly ash from a DBB (Dry Bottom Boiler) and the

slag and fly ash from a WBB (Wet Bottom Boiler)· Losses through conduction and radiation

8.5.9.1 Short-term Energy Efficiency Improvement projects for power plants

i. Installation of online oxygen analyzer to improve combustion efficiency ofBoiler

ii. Preventing air infiltration into boiler flue gas path particularly in waste heatrecovery zone

iii. Installation of waste heat recovery system for boiler blow downiv. Installation of LP steam air heater for FD fan air inlet to boilerv. Optimization of operating breakdown voltage of ESP'svi. Proper insulation of steam and condensate linesvii. Proper and regular monitoring & replacement of defective steam trapsviii. Wetting of coal with higher fines percentage to avoid the segregation effectix. Installation of delta to star converters for lightly loaded motorsx. Use of translucent sheets to make use of daylightxi. Installation of timers for switching on/off yard & outside lightingxii. Switching off transformers based on loadingxiii. Optimization of TG sets operating frequency based on user requirementxiv. Optimization of TG sets operating voltagexv. Replacement of aluminum blades with aerodynamic FRP blades in cooling

towersxvi. Installation of Temperature Indicator Controller (TIC) for optimizing cooling

tower fan operation based on ambient conditionsxvii. Minimizing compressed air leakages and optimization of compressed air

network operating pressuresxviii. Segregation of service air and instrument air systemsxix. Installation of VFD for cooling tower make up water pump with water basin

level control feed backxx. Installation of VFD for DM water transfer pumpxxi. Ensuring total closure of standby equipment dampersxxii. Reduction in RPM of Coal Handling Plant's Dust Extraction Blowers

Case Study 9: Control of excess air by installing O monitoring system in 2

boiler of CPP system

Brief

By monitoring the O level of 5-6 % of the flue gas on continuous basis, the input of 2

excess air level can be maintained, which shall help in regulating the heat loss to the environment.

Before Improvement After ImprovementPresently, there is no indication of % O in flue gases of this boiler. 2

Without this, optimization of efficiency of boilers is not possible on continuous basis, especially when BF gas and Mix gas availability is changing.

By achieving 6% O by installation of 2

monitoring systems (zirconium oxide online oxygen analyzer), following was achieved: Increase in boiler efficiency by 3.4%.Reduction in FD fan airflow by 60%.Reduction in ID fan flow by 60%.

283282

Energy savings

The following table summarizes the overall effect of O monitoring control.2

Effect of O control on boiler performance2

Annual hours of operation HP-4 boiler = 7690 hours Average steam generation = 77.48 TPH (average during trials)Annual saving in fuel

= Steam flow x Enthalpy of steam x (1/Eff1 - 1/Eff2) x Annual running hours GCV of coal

Where, Eff1 = Existing efficiency of boiler Eff2 = Likely efficiency of boiler after modifications in controlGCV of coal is used to convert the fuel energy saved in terms of reduction in coal consumption for same total steam output of all boilers combined.Annual saving in fuel input = 77.48 x 639 x (1/0.87 - 1/0.904) x 7690

3825 = 4303 tonnes per year

Price of Coal = Rs. 1000/ tonneAnnual monetary saving = 4303 x 1000 = Rs. 43,03,000Annual savings : Rs 4.3 MillionInvestment required : Rs. 5 Million Payback period : 13 months

Case Study 10: Use of Variable frequency drives on FD fans in place of existing Inlet vane control

Brief

Annual savings : Rs. 1.16 MillionInvestment required : Rs 0.5 MillionPayback period : 6 months

Case Study 11: Reduction of cutoff pressure of air compressor

Brief

Before Improvement After ImprovementThe existing FD fan motors are 45 & 85 kW rated at 415 V. Input power of each fan is about 50 and 68 kW.

For a flow reduction of about 50%, reduction in power input to FD fans is 50% as compared to the existing IGV control. The power saved is 60KW.

Before Improvement After Improvement The compressed air in gas-based power plant is used for supplying to the instrumentation and plant air requirement and the pressure

2kept for cutoff is 9 kg/cm .

As the application is basically for instrumentation and plant airrequirement, the pressure was

2 2reduced from 9 kg/cm to 7.5 kg/cm .

Parameter

% O2 Excess air, % Boiler efficiency, % F

3D fan airflow, Nm /h3ID fan airflow, Nm /h

Existing Condition

12.6 148 87 118976232590

After installing O2 monitoring & control system

6 40 90.4 64392149858

Energy savings

2Energy savings by reducing the operating pressure to 7.5 kg/cm (cut-off pressure) is as follows:

Annual Savings : Rs 0.35 Million Investment required : nilPayback period : Immediate

Case Study 12: Installation of Automatic Temperature Controller (ATC) for switching ON/OFF cooling tower fan

Brief

Energy savings

% Savings by temperature control = 15%

Annual savings : Rs 1.174 Million Investment required : Rs 0.2 MillionPayback period : 2 months

It was observed that the operations of the Cooling Tower Fan installed on the Cooling Tower is not controlled based on the ambient climatic conditions vis-à-vis temperature differential (delta T). As a result, CT fan was operating continuously without taking into account the inlet & outlet temperature variations.

If outlet cooling water temperature is lower than the desired value, then natural cooling is sufficient. This means that the cooling tower fans can be switched off by i n s t a l l a t i o n o f A u t o m a t i c Temperature Controllers during this period.

Before Improvement After Improvement

Total Cooling Tower KWh consumption/month

= 429.36 x 710 = 304845.6 KWh/month

Savings in Cooling Tower Fan Electricity Consumption

= 304845.6 x 0.15 x 12 KWh/annum= 548722 KWh/Annum

Annual savings in terms of Rupees = 548722 x 2.14 = Rs. 1174265.25 per annum

Annual % savings in internal electricity consumption

= 548722/(12 x 4.97 MU x 10^6) = 0.92%

% Savings by pressure 2reduction from9 kg/cm

2to 7.5 kg/cm

= (Present kW/100 CFM – kW/100 CFM at suggested pressure)/ Present kW/100 CFM= (22.23 – 19.5) x 100/22.23 = 12.28%

= Monthly Compressor kWh consumption x % Savings= 110361 x 0.123 = 13574 kWh/month

Annual savings = 13574 x 12 = 162888 kWh = Rs. 3, 48,580 per annum

Savings in Compressor kWh consumption/month

285284

8.5.9.2 Medium term Energy Efficiency Improvement projects for power plants

i. Installation of economizer / air pre-heater for Boilerii. Installation of VFD for Condensate Cooling Water (CCW) pump and closed

loop control based on discharge header pressureiii. Reduction of heat rate of gas turbines by optimizing NOx water injection

and arresting leakages through bypass dampersiv. Installation of Turbine inlet air cooling to increase power output of gas

turbinesv. Installation of low excess air burnersvi. Installation of lower head fan for boiler ID fanvii. Installation of Variable fluid coupling or VFD for condensate extraction

pumpviii. Utilization of flash steam from boiler blow down for de-aerator heatingix. Installation of capacitor banks for PF improvementx. Replacement of rewound motor with high energy efficiency motorsxi. Utilization of energy efficient lighting systemsxii. Installation of LED panel lampsxiii. Replacement of old and inefficient compressors with screw or centrifugal

compressorsxiv. Replacement of V-belts with synthetic flat belts

Case Study 13: Install VFD for boiler ID fans and PA fans

Brief

In a major captive power plant, three circulating fluidized bed combustor (CFBC) were in operation. Each boiler has two ID fans and three Primary Air (PA) fans.

Energy savings

Annual savings : Rs. 6.0 Millions Investment amount : Rs. 10.0 MillionPayback period : 20 months

Before Improvement

All the fans had higher capacity & head by design and controlled either by IGVs or Dampers to meet the operating requirements.

The estimated operating efficiency of the fans was in the range of 60% - 65% as against design efficiency of 80%. It was confirmed that the fans were operating in an energy inefficient zone on the fan performance curve.

After Improvement

Variable frequency drives were installed for 6 nos of ID fans and 9 nos of PA fans to control the speed of the fan with respect to operation of the boiler. The inlet guide vanes (IGVs) were kept fully opened after the VFD was installed.

-

The advantage of installing a variable frequency drive for the boiler ID fans is as follows: § Energy saving § Precise control of parameters

Case Study 14: Replacement of fin fan cooler by water-cooled Plate Heat Exchanger (PHE )

Brief

Fin-Fan Cooler is used to cool GT Lube Oil, Turbine Legs, Atomized Air & Generator Air. Here the cooling is achieved by air-cooled heat exchanger. At a time on average basis 4 fans operate per GT with a combined power consumption in 4 fans = 91.27 kW.

• In tropical climates, for normal cooling application water-cooling is more energy efficient. • Air-cooling is convenient when an average ambient temperature drop is

O below 20 C & ambience is relatively dust free. • Therefore it was recommended to replace Fin-Fan coolers by water-cooled PHEs.

Energy savings

Annual savings : Rs 2.0 MillionInvestment required : Rs 2.0 MillionPayback period : 12 months

Case Study 15: Replacement of Conventional T-8 tube lights with T-5 tube lights with Electronic chokes in a power plant

Brief

The normal tube lights with conventional chokes consume about 54 W as compared to the T-5 tube lights, which consume about 30 W. By replacing them with T-5 tube lights, there is a saving of 24 W per light. The efficiency and the lux produced are better along with the longer life.

Energy savings

Wattage Saving in Wattage Nos. in operation Hrs in operation kWh saving per year

Annual saving in term of Rs

T –8 54 Watt

- - - -

-

T -5 30 Watt 54 – 30 = 24 Watt 549 10 hrs/day 30 x 10 x 549 x 12 x 24

1000 = 47434 kWh/ year47434 x 2.14 = Rs 1, 01,508

After ModificationBefore Modification

Energy being consumed by fin fan cooler with average running of 4 fans was 91.27 kW per hour.

By replacing these with water cooled PHE, there was a saving of 30.55 kW. Thus there was a total saving of 60.72 kW per hour or 9.62 lakhs units/year.

287286

Annual savings : Rs 0.1 Million Investment required : Rs 0.41 MillionPayback period : 48 months approx

Case Study 16: Removal method of scale from inside condenser tubes

Brief

The ball cleaning method for removing scales deposited inside the condenser tube becomes less effective as time goes by. The method introduced here is free from such deterioration, and is able to restore and maintain the heat exchanging effectiveness of the condenser as designed. The method involves use of 27 mm dia sponge balls followed by plastic coat ball (G-ball) & then Corborundum ball (C-ball). Besides cleaning is conducted once a week or when vacuum detoriates to 3mm Hg.

1) For removing scales deposited inside the condenser tube, cleaning withsponge balls, 26mm diameter, was previously used.

2) Sponge balls eventually lose their surface roughness, or become deformed,and become unable to contact the inside wall closely.

3) Hard scales that cannot be removed by the sponge balls are graduallydeposited.

4) Soft scales consist of silica and organic substances, and hard scales consist ofmanganese substances.

5) As a result, the vacuum of the condenser deteriorates from the original levelby about 5mmHg.

Energy savings

When applied to a 250 MW coal fired power plant (operating rate 82.2%):

Annual savings (operated for 300 days) : Rs 14.96 million Investment required : Rs 0.12 million Payback period : Less than 1 month

8.5.9.3 Long-term Energy Efficiency Improvement projects for power plants

i. Reduction of one stage of feed water pump or installation of VFD with feedback control to exactly match with system pressure

ii. Installation of VFD for Boiler ID/FD fansiii. Installation of VFD for Boiler feed water pumpiv. Installation of CFBD boilers for efficient combustionv. Conversion to AFBC technology from chain grate/spreader stoker boilersvi. Installation of high efficiency turbinesvii. Installation of Distributed control system (DCS) for plant operation and

monitoring

Deterioration of vacuum Saving of fuel (under rated output)

Before improvement

6mmHg

—

After improvement 1mmHg

0.65 ton/h

Case Study 17: Convert Spreader Stoker Boilers to Fluidized Bed Boilers

Brief

Energy savings

Annual savings : Rs. 10.50 Million Investment amount : Rs. 27.0 MillionPayback period : 31 months

Case Study 18: Reduction in stages in multistage pumps of LP and HP pumps of Boiler Feed Pumps

Brief

Reduction in number of stages of LP and HP pumps has led to reduction in head given by boiler feed pumps thus reducing the input power of the motors.

• Selection of operating/design pressure of pumps is made broadly as` equal to working pressure plus margins considered safe at each level of

decision-making.

• Therefore, in the plant, control valves are provided and design valuesare met with by throttling.

Instead of throttling, if the number of stages is reduced, then the head developed is as per the actual requirement, which reduces the input power of the motor.

o 78% with this modifica

ulted in an annual coal s

289288

Energy savings

Annual savings : Rs 23.2 Million Investment required : Rs 3.6 MillionPayback period : 2 months

Case Study 19: Use of split mechanical seal in Condensate Extraction Pumps

Brief

Use of gland packing for sealing in pumps leads to the wastage of DM water at 1 ltr per hour. If mechanical seal replaces the gland packing, then reduction in leakage of DM water, reduction of downtime and reduction in maintenance cost takes place.

Energy savings

• In one year about 8760 liter of DM water gets leaked from one pump.• This is worth Rs. 123760 per year in terms of money

Annual savings : Rs 0.124 Million Investment required : Rs 0.13 MillionPayback period : 12 months

After ReplacementBefore Replacement

By using mechanical seal on the CEP, the sleeve cost could be directly saved. Due to the mechanical seal installation on CEP, the pump runs for a longer time as compared to gland packed pumps where pump is required to be stop regularly for replacing the gland packing. This leads to save of down time and main power.

In case of gland packed CEP, almost 1 liter per hour of DM water is lost. Due to the more wear & tear of sleeve in case of gland packed CEP, the sleeve is replaced frequently and hence this adds to more maintenance cost of the pump.

After ReplacementBefore Replacement

LP Boiler feed pumps:The input power reduction by removal of stages = 48 kWAnnual Saving in kWh = 48 x 24 x 330 = 3, 80,160 (Average working days per year = 330)

HP Boiler Feed Pumps:The input power reduction by removal of stages = 1316 kWAnnual Saving in kWh = 1316 x 24 x 330 = 1, 04, 22,720

Boiler water handled for LP section 3is 75 m /hr and HP section is 367

3m /hr. Desired flow rates are achieved by throttling the delivered head of pump.

For LP Boiler: From 214 to 41 mFor HP Boiler: From 1440 to 756

Case Study 20: Gravity feeding of make-up water at PPCL, Delhi

Brief

Energy savings

Net electrical energy saving of 45 kW

Annual savings : Rs 1.5 Million Investment required : Rs 0.1 MillionPayback period : One Month

8.10 Case Studies

Case Study 21: Low-pressure operation of natural circulation boiler

Brief

Fuel-saving operation through minimizing the reduction of thermal efficiency under low load operation of a natural circulation or forced circulation drum boiler.At a power plant relatively aged or the one operated to adjust the amount of power generated (i.e., an adjustment thermal power plant), the following problems are posed.

1) When operated for power adjustment, mainly during night, minimum load operation comes to around 40%.

2) When operated under minimum load at a constant pressure, there arise thefollowing problems:• Increased pressure loss due to the narrowed regulation valve of the

turbine.• Steam consumption of the steam turbine to drive the boiler feed water

pump is not negligible from the point of the thermal efficiency of theplant.

Energy savings

1) Under low load operation, the gross thermal efficiency can be increased by0.5 - 0.6% by reducing the pressure.

2) When the low-pressure operation was applied to the minimum load(75,000kW) operation at a 350,000kW generation unit, consumption ofC-grade heavy oil was saved by 291kl per year

After ModificationBefore Modification

The cooling tower make up at Pragati Power Station is fed with one pump of discharge capacity of

3350m /hr with 45 kW driving motor.

Onsite observation revealed the fact that the cooling tower basin is well below source of make up water.

Make up water is fed to CT basin under gravity instead of pumping it.

Thus the make up pumps are kept as stand by and make up water is being fed due to gravity.

291290

Case Study 22: Reduction of starting-up time of cold plant

Brief

When starting up a power plant after a long shutdown (a cold plant), energy loss in starting up is reduced by reducing the starting-up time by omitting/shortening certain steps like turbine warming time, hot water cleaning of turbine before start-up.

Energy savings

Case Study 23: Separate type heat pipe exchanger

Brief

Energy savings

1) Release of SOx and dust is less than an after-burner system.2) Low running cost and high reliability.3) In comparison with the after-burner system, burner fuel cost can be saved by

20 - 35 litre/kWh.4) With a 500MW class of boiler, saving of approximately 15000 kl/year is

possible.

Annual savings : Rs 3.45 million Investment required : Rs 1.75 millionPayback period : 6 months

Before Improvement After ImprovementThe conventional starting-up schedule of a cold plant requires 29 hours in total.In the starting-up time, a long time is required for warming up the turbine.

The starting-up time is reduced by 4 hours and 45 minutes (from 29 hours to 24 hours and 15 minutes) by ommitting/shortening. Certain Step: viz turbine warming time, not water cleaning of turbine before start up making it possible to start supplying electric power earlier than before.Combustion of light oil in the boiler for starting up can be saved by 38kl per onestarting-up. Saving per year, which depends on the number of starting up peryear, cannot be stated definitely. With increasing operation of the adjustment thermal power plants, which have frequent stops and starts, there are significant savings by this operation method

Before Improvement After ImprovementWhen wet-type desulfurization is applied to a power generation boiler, some problems are caused such as; insufficient diffusion from the stack and occurrence of white smoke (white steam), because treated gas is discharged from the stack as moisture-saturated gas at 52 - 56°C

To solve these problems, a heat exchanger utilizing heat pipes is installed which reheats the treated exhaust gas through the heat exchange with the inlet gas to the desulfurization equipment.

Case Study 24: Avoiding Unnecessary Pumping for CT make up water

Brief

Energy savings

Annual savings : Rs 0.525 MillionInvestment required : Rs 0.9 MillionPayback period : 21 months

Case Study 25: Attaining proper vacuum in condenser by providing spray pond for steam ejector

Brief

Energy savings

Annual savings : Rs 7.5 Million Investment required : Rs 3.6 MillionPayback period : 6 months

Before Improvement After Improvement

In a Power House, attaining required vacuum at condenser was a recurring problem. Reason for this appears to be dirt, soft scaling material or plastic in the incoming water.

Spray pond can be created rather than cooling tower, which is a costly proposition. Saving results due to reduced steam consumption in ejectors.

Required flow 3200 m /hrHead at inlet of economizer 950 + 50 + 100 = 1100 m WCEstimated power at 60% efficiency (200 x 9.8 x 1000 x 1100)/ (3600 x

1000 x 0.6) = 998 kWExisting Power consumption 1182 kWSavings kW (1182 – 998) = 184 kW At CEP side, potential (130 -54) 76 kWSaving in monetary terms is (184 + 77)

== =

== = = 260 kW x 3.59 x24 x 330

= Rs 75 lakhs

Before Improvement After ImprovementMake up water comes to first filter on sand bed gravity filter. Output of filters is received in the storage tank through channels. From underground storage tank,water is pumped to cooling tower basin.

Pump is consuming 31 kW

Elevation of the filter and channel is above cooling tower basins. Thus, passing water directly from the channels to cooling tower basin has eliminated pumping.

All the power 31 kW could be saved with direct piping. An auto control valve was however provided to stop flow if the level of the basin went up to basic requirement.

292

References

1. Power Scenario at a Glance - CEA - May 20082. Kakodkar, Anil; "Evolving Indian Nuclear Programme: Rationale and

Perspective"' Indian Academy of Science, Bangalore, July 20083. LBNL - 54828: Emerging Energy Efficient Technologies in Industry case

studies of selected technologies - May 20044. Coal Meeting the Climate Challenge: Technology to reduce GHG emissions;

World Coal Institute.5. Annual Report (2006-07) of Department of Atomic Energy (DAE), GoI6. Report of the working group on Power for 11th Plan (2007-12)7. Report of the working group on R&D for the Energy Sector for the

formulation of the 11th Five Year Plan (2007-12)th8. Report of the working group on new and renewable energy for 11 Five Year

Plan (2007-12)9. "Clean Coal Technologies for Developing Countries", World Bank Technical

paper no. 286, Energy Series, E. Stratos Tavonlareas & Jean- PierreCharpentierre, 1995

10. National Energy Map of India: Technology Vision 203011. CII - IREDA Publication: "Investors Manual on Energy Efficiency".12. LBNL - 62806; World Best Practice Energy Intensity Value for Selected

Industrial Sectors, February 2008.13. LBNL - 57293; Assessment of Energy use and energy savings potential in

selected industrial sector in India, August 2005.14. TERI Energy Directory and Yearbook 200715. Statistical Abstract 2007-CSO16. Annual Report, NPCIL17. Japan Energy Conservation Directory18. Yadav, R.K., "Energy and water conservation in cooling water system of

thThermal Power Station: A Case Study of Pragati Power Station", 9Greentech Global Environment Conference 2008, Goa, Page 237-281

19. BP Statistical Review, June 200820. www.iea-coal.co.uk 21. www.energymanagertraining.com22. www.fuelcells.com23. www.fuelcelltoday.com

293

9.1 Introduction

Steel plays an important role for the development of infrastructure in the growing economy. With the economic growth rate of 8% - 9%, during the last few years, the demand for steel has touched new heights. In fact, with opening up of the economy in the early nineties, country experienced rapid growth in steel making capacity. Large integrated steel plants set up in private sector and capacity expansion of

thpublic sector plants has contributed to making India the 5 largest global crude steel producer in the year 2006. India is expected to become the second largest producer of steel in the world by the year 2015.

9.2 Present Capacity & Growth Potential

Data relating to production, consumption, import & export of finished steel (alloy & non-alloy) and crude steel from the year 2002-03 onwards is given in table 9.1 below:-

*Provisional(Source : Annual Report of Ministry of Steel, GoI, 2007-08)

thThe projected total demand of finished steel by the end of XI plan (i.e. year2011-12) is 70.34 million tonne and production of crude steel is 80.23 million tonne. These figures of demand and production are likely to increase to 90 million tonne and 110 million tonne respectively by the year 2019-20.

9.3 Iron & Steel Manufacturing Process

The two main routes for the production of steel are :

• Production of primary steel using iron ore and scrap• Production of secondary steel using only scrap.

9.3.1 Steel Production from Iron Ore

Steel production at an integrated steel plant involves the following four basicsteps i.e,

i. Production of coke and sinter / pallets from iron fines - Material preparationii. Reduction of iron ore in blast furnace-Iron making

Table 9.1: Production, Consumption, Import, Export of Finished steel & crude steel production.

(in million tonnes)

Chapter - 9

Iron & Steel Industry

2002-

03

2003

- 04

2004

– 05

2005- 06

2006-07

2007-08(April –

December)*Production

37.166

40.709

43.513

46.566

52.529 40.117Consumption

30.677

33.119

36.377

41.433

46.783 36.992Import

1.663

1.753

2.293

4.305

4.927

5.325

Finished Steel

including

Alloy Steel

Export

4.517

5.207

4.705

4.801

5.242 3.850

Crude Steel Production 34.707 38.727 43.437 46.460 50.817 39.608

295294

iii. Processing of molten iron to produce steel -Steel makingiv. Steel forming and finishing.

In addition, the alternative route of iron making is Direct Reduction of Iron Process (DRI)

9.4 Production of Crude steel in India through different processes

Traditionally, Indian steel industry were classified into Main Producers (also referred to as the integrated iron & steel plants for example SAIL (Steel Authority of India Ltd.) plants, Tata Steel and Vizag Steel / RINL (Rashtriya Ispat Nigam Ltd.) and the Secondary Producers. However, with the coming up of larger capacity Steel making units, of different process routes, the classification has been charcterised as Main Producers & Other Producers. Other Producers comprise of Major Producers namely Essar Steel, JSW Steel and Ispat Industries as well as large number of Mini Steel Plants based on Electric Furnaces and Energy Optimising Furnaces. Besides the steel producing units, there are a large number of Sponge Iron Plants, Mini Blast Furnace units, Hot & Cold Rolling Mills & Galvanising/Colour Coating units which are spread across the different states of the country. The following table 9.2 highlights the contribution of the private and public sector in crude steel production in the country:

Table 9.2: Sectorial Production of Crude Steel

(in million tonne)

(Source: Annual Report of Ministry of Steel, GOI, 2007-08)

9.5 Energy Consumption in Steel Plants

9.5.1 Energy Intensity

Iron & Steel industry in India is highly energy intensive. Major energy inputs in the sector are coking coal, non-coking coal, coke & electricity.

Energy demand in this sector is expected to be nearly 28% of the total industrial energy demand in 2030, which is roughly between 20-22% at present. The demand for coal in steel sector is expected to grow by 5.2% per year (upto2030) and natural gas demand to grow by 6% a year. The electricity demand in the same period is likely to grow 8% per year.

9.5.2 Energy Consumption

The specific energy consumption in Indian Steel plants is quite high. It ranges between 25.5 GJ/ tcs to 34.2 GJ/ tcs (tonne of crude steel). On an average, the SEC (Specific Energy Consumption) is 30 GJ/ tcs in India, which is almost double of the World's best plants. There is variation of specific energy consumption in different steel plants. This is mainly because of different processes, quality of coal, types of

Public Sector

Private sector

TOTAL PRODUCTION % Share of public sector

2003-04

15.8

22.9

38.7 40.0

2004-05

16.0

27.543.5

36.6

2005-0617.0

29.5 46.5

36.5

2006-0717.0

33.850.8

33.5

products produced & energy efficiency measures adopted by the plants. The details of specific energy consumption by the Indian steel plants (GJ/ tcs) is given in table 3 below:-

Table 9.3: SEC of Indian Steel Plants (GJ/ tcs)

(Source : Annual Report of Ministry of Steel, GoI, 2007-08)

The major energy consuming process in iron making are coking, sinter making & blast furnace. They consume about 61.3% of the total energy. The slabbing mill, and hot strip mill together with others account for 36.5% energy consumption. The table 9.4 gives the major portion of energy consumption in iron making.

Table 9.4 : Major portion of energy consumed in iron making

(Source : Handbook of Energy Conservation by H. M. Robert & J. H. Collins)

Plant

2006-07

Bhilai Steel Plant (BSP) 28.53

Durgapur Steel Plant (DSP) 29.58

Rourkela Steel Plant (RSP) 33.39

Bokaro Steel Plant (BSL) 29.66

IISCO Steel Plant (ISP) 34.26

SAIL (as a whole) 29.95 RINL 27.32

TATA Steel 28.07

JSW Steel 25.52

Process % of total energy

CokingSinter making

Blast furnace

BOF (LD)

Slabbing mill Hot strip mill

Cold rolling mill

Other(including losses)

Total

Energy consumed 6

10 tonne CSkCal/

1.033

0.967

3.519

0.202

0.483 1.080

1.025

0.91

9.000

11.5

10.7

39.1

5.4

12.0

11.4

7.7

100.0

61.3% in iron making

2.2% in steel making

36.5% in rolling and others

2.2

297296

The details of specific energy consumption by process in an Indian Steel Plant is given in table 9.5 below:

Table 9.5 : Specific Energy Consumption

Description

Qty. of energy

consumed Produced

Energy in heat values 6(10 kCal)

consumed Produced

Coke oven (per tonne of coke)

Coal (tonne)

1.489

- 10.423 -

BF coke (tonne)

-

1.0 - 7.000

Electricity (kWh)

27

- 0.067 -

COG (M³)

208

416 0.853 1.706

Steam (kg)

100

- 0.087 -

Coke breeze (kg)

-

150 - 1.050

Crude tar (kg)

-

40 - 0.034

Total

11.430 9.790

Net energy consumed per tonne of BF coke

1.640

Net energy consumed per tonne of CS

(at coke rate of 700 kg and HM ratio of

900 kg)

1.033

Sinter plant (per tonne of sinter)

Coke breeze (kg)

100

- 0.700 -

Electricity (kWh)

100

- 0.250 -

COG (M³)

20

- 0.082 -

BFG (M³)

50

- 0.043 -

Total

1.075 -

Net energy consumed per tonne of sinter)

1.075 -

Net energy consumed per tonne CS (at sinter rate

of 1000 kg and HM ratio of 900 kg)

0.967

Blast furnace (per tonne

of hot metal)

Coke (kg)

700

- 4.900 -

Electricity (kWh)

30

- 0.075 -

BFG (M³)

1000

2500 0.870 2.075

Steam (kg)

160

- 0.140 -

Total

5.985 2.075

Net energy consumed per tonne

of HM

3.910

Net energy consumed per tonne of CS

(at HM ratio of 900 kg)

3.519

Steel melting shop (per tonne

of ingots)

Electricity (kWh)

40

- 0.100 -

Steam (kg)

25

140 0.022 0.122

COG (M³) 20 - 0.082 -

Oxygen (M³) 70 - 0.120 -

Total 0.324 0.122

Net energy consumed per tonne of CS 0.202

(Source :Handbook on Energy Conservation by H.M. Robert & J.H. Collins)

9.6Energy Efficiency in Steel Industry in India

In the journey of progress, the Indian Steel Industry has taken significant steps in improvement of productivity, conservation of natural resources, Research and Development, import substitution, quality upgradation and environment management. Some notable developments are:

1. Introduction of Stamp Charging and Partial Briqueting of Coal Charge (PBCC) for production of metallurgical coke - in this process, it has been made possible to replace part of the metallurgical coal requirements by non-coking/ semi-coking coal, with higher strength of the coke and less emission.

2. Installation of energy recovery coke ovens - in order to meet the power requirements as well as to reduce emission.

3. Use of non-coking coal in iron making - processes such as Corex have now been introduced in some of the steel plants to produce hot metal by predominantly using non-coking coal. Coal Dust/ Pulverised Coal Injection System has been introduced in several blast furnaces to partially substitute Coke. In addition, there has been large scale growth of sponge iron units based on non-coking coal.

Slabbing mill (per tonne of ingots)

Electricity (kWh) 45 - 0.112 -

BFG (M³) 450 - 0.371 -

Total 0.483

Net energy consumed per tonne of CS 0.483

Hot strip mill (per tonne of slabs)

Electricity (kWh) 150 - 0.375 -

COG 140 - 0.574 -

BFG (M³) 420 - 0.366 -

Steam (kg) - 50 - 0.043

Total 1.315 0.043

Net energy consumed per tonne of slab 1.272

Net energy consumed per tonne of CS 1.080

Cold rolling mill (per tonne of CR coils)

Electricity (kWh) 250 - 0.625 -

Steam (kg) 250 - 0.219 -

COG 70 - 0.287 -

BFG (M³) 210 - 0.183 -

Total 1.314 -

Net energy consumed per tonne of CRC 1.314 -

Net energy consumed per tonne of CS 1.025

299298

4. Use of Direct Reduced Iron (DRI) / Sponge iron in steel making-earlier, only scrap could be used as a feed material in electric arc furnaces. With growing scarcity of scrap, a replacement could be found in the form of DRI produced from iron ore with reformed natural gas/ non-coking coal as reluctant.

5. Use of hot metal in electric arc furnaces - setting up of Basic Oxygen Furnace is capital intensive and successful only at a large scale.

6. Adoption of continuous casting - The first solidified form of steel in the melting shops used to be ingots. With the advent of continuous casting in late seventies and now the adoption of thin slab casting has resulted in energy saving. Today the

continuously cast steel output is 66%.

7. Reducing coke consumption in blast furnaces and improving productivity - Indian blast furnaces used to consume as high as 850 kilograms of coke per tonne of hot metal and Blast Furnace productivity were hovering at less than one tonne per cubic meter per day. Introduction of modern technologies and practices viz. high top pressure, high blast temperature, pulverized coal injection, attention on burden preparation & distribution, and higher use of sinter in place of lumps have resulted in reduced coke consumption and improved productivity. Today, coke rate in some of the blast furnaces is less than 500 kg/ tonne hot metal & productivity exceeding 2 tonne per cubic meter per day.

8. Enhancing steel quality - Earlier the steel making furnaces used to complete the steel making within the furnaces itself. With the introduction of modern steel making technologies/practices and secondary refining technologies such as ladle metallurgy, vacuum degassing etc., it is now possible to produce steel of much lower inclusion and much lower content of oxygen, nitrogen and hydrogen. The ladle furnace technology has also made it possible to cut down the steel making time in converters or Electric Arc Furnaces and enable to produce steel of low sulphur and phosphorus content.

9. Efforts to reduce energy consumption and emissions - Iron and Steel making involves energy intensive processes. The international norm of energy consumption is 4.5 to 5 Giga calories per tonne of crude steel. With setting up of modern equipments and beneficiation of raw materials, Indian Steel plants have been able to achieve energy consumption at the level of 6.5 to 8.5 Giga calories only. Further, steps are being taken to achieve much lower energy consumption

thand corresponding lower Green House Gas (GHG) emissions by the end of 11 Five Year Plan. With the growth of steel industry, increasing attention is being paid to environment management. Steps such as afforestation, installation of pollution control equipments etc. are likely to abate the pollution emanating from steel industry. Further, the Indian iron and steel industry is now taking the advantages of Clean Development Mechanism under the Kyoto Protocol thereby reducing pollution and energy consumption.

9.6.1 Directory of ENCON measures by the Indian Steel Industry

In Indian steel industry, the specific energy consumption ranges from 25.5 GJ/ tcs to 34.2 GJ/ tcs, depending on the process & product produced. Average SEC of Steel Industry in India is 30 GJ/ tcs as compared to 26 GJ/ tcs of US & 18 GJ/ tcs of Japan. Over the years, a number of energy conservation measures have been taken by each plant.

A Important energy conservation schemes implemented/under implementation are listed below :

1. Fabrication and erection of thyrister control for 800 tonnes shear in Blooming and Billet mill (BSP).

2. Installation of energy efficient dry fog dust suppression system in BlastFurnace stock house (BSP).

3. Installation of side burner in Furnace of Rail Mill (BSP).4. On-line sealing of steam blast and gas leakage (DSP).5. Insulation of steam lines and other hot surfaces (DSP).6. Commissioning of alternate Blast Furnace gas line for Blast Furnace stoves

(RSP).7. Steam impingement on sinter bed introduced in both the strands of Sinter plant

(RSP).8. Commissioning of vapour absorption chiller in Coal Chemicals Department

(RSP).9. Change over from 9-2 pushing series to 5-2 pushing series(BSL).10. Resumption of coal dust injection in Blast Furnace after capital repair (BSL).11. Installation of 18 kW motors in place of 24 kW motors in 92 nos. of bases in

Annealing Line of Cold Rolling Mill (BSL).12. Installation of electronic belt weigh feeder at coal handling bunker (IISCO). 13. Conversion of four stroker type boilers at Power House from coal firing to

By Product Gas firing thereby reducing the coal consumption in power generation (TISCO).

14. Increased recovery of LD gas from a level of 37 Normal cubic metre per tonneof crude Steel to a level of 56 Normal cubic metre per tonne of crude Steel. Therecovered LD gas is mixed with BF gas for utilisation at Power Houses(TISCO).

15. Installation of variable frequency drive to reduce electrical energyconsumption (TISCO).

16. Increase in high top pressure at E Blast Furnace, thereby increasing the blastfurnace productivity and reduction in blast furnace coke rate (TISCO).

17. Installation of Top Recovery Turbine at H Blast Furnace (TISCO).18. Modification in LD gas network to recover additional LD gas from another

LD Shop (TISCO).19. Split blowing at Blower Houses to reduce steam consumption for blast furnace

blowing (TISCO).20. Introduction of COREX Technology for Iron Making (JSW).21. The first 1.2 MTPA non-recovery coke ovens with stamp charging and co

-generation of 85 MW waste heat power (JSW). 22. Main gates and street lights are replaced by solar lights (JSL).23. Installation of air-preheaters in waste heat recovery boilers (JSPL).

301300

24. Installation of dual fired boiler (1×63 TPH) substituted coal by Blast FurnaceGas partially (JSPL).

25. Installation of non-recover type, environmental friendly coke ovenplant(JSPL).

26. Replacement of petro-fuel by producer gas (JSPL).27. Introduction of metallurgical coke fines in Electric Arc Furnace by coke

injector as cheap substitute of CPC (JSPL).28. Waste heat recovery boilers (WHRB) installed to utilise sensible heat of off-gas

of DRI-Kilns to generate extra electrical power emission (JSPL).29. Other conventional energy saving measures adopted are :

a) LD Gas recovery,b) 100% Continuous Casting,c) Highest hot charging of slabs,d) Coal injection in Blast Furnaces,e) High Hot blast Temperature in stoves

9.7 Details of the World's Best Processes

9.7.1 Blast Furnace- Basic Oxygen Furnace (BOF) Route

During the ironmaking process, sintered or pelletized iron ore is reduced using coke in combination with injected coal or oil to produce pig iron in a blast furnace. Limese is added as a fluxing agent. Reduction of the iron ore is the largest energy-consuming process in the production of primary steel. The best practice blast furnace is a modern large scale blast furnace. Fuel injection rates are similar to modern practices found at various plants around the world. The highlights of the process are given below :-

Blast Furnace and BOF

• Fuel injection rate approx. 125 kg/t hot metal• Oxygen is used for enrichment• Pressurized operation for blast furnace at four bar• Power recovery using Top Gas Power Recovery Turbine (wet type)• Heating efficiency of hot gas stoves is maintained at around 85% using staggered parallel operation of 3 to 4 stoves per furnace.• Scrap input typically 10% - 25% in BOF Process• BOF gas and sensible heat recovery

Coke Plant

• Electrical exhausters are installed• VFDs for motors and fans• Coke Dry Quenching (CDQ) saves additional 1.44 GJ/t (49 kgce/t) coke

(kgce = kilograms coal equivalent)

Sinter Plant

• Coke and breeze is used as fuel and gas as ignition furnace fuel• Moving Grate technology is used• Waste heat recovery from sinter exhaust cooler

9.7.2 Smelt Reduction - Basic Oxygen Furnace Route

Smelt reduction processes are the latest development in pig iron production and omit coke production by combining the gasification of coal with the melt reduction of iron ore. Energy consumption is reduced because production of coke is abolished and iron ore preparation is reduced.

Currently, the COREX process (Voest-Alpine, Austria) is commercial and operating in South Africa, South Korea and India, and under construction in China. The COREX process uses agglomerated ore, which is pre- reduced by gases coming from a hot bath. The pre-reduced iron is then melted in the bath. The process produces excess gas, which is used for power generation, DRI - production, or as fuel gas.

The best practice values for the COREX plant are based on the commercially operating plant at POSCO's Pohang site in Korea. The plant coal consumption is around 100 kgce/t (Kg Coal Equivalent), 75 kWh/t (9.2 kgce/t) hot metal

3electricity and 526 Nm /t hot metal of oxygen. It exports offgases with an energy value of 13.4 GJ/t (457 kgce/t) hot metal.

9.7.3 Direct reduced Iron (DRI) - Electric Arc Furnace (EAF) Route

DRI, Hot Briquetted Iron (HBI), and iron carbide are all alternative iron making processes. DRI, also called sponge iron, is produced by reduction of the ores below the melting point and has different properties than pig iron. DRI serves as a high-quality alternative for scrap in secondary steelmaking.

In the EAF steelmaking process, the coke production, pig iron production, and steel production steps are omitted, resulting in much lower energy consumption. To produce EAF steel, scrap is melted and refined, using a strong electric current. DRI is used to enhance steel quality or if high quality scrap is scarce or expensive. Several process variations exist using either AC or DC currents, and fuels can be injected to reduce electricity use.

The best practice EAF plant is state-of-the-art facility with eccentric bottom tapping, ultra high power transformers, oxygen blowing, and carbon injection. The furnace uses a mix of 60% DRI and 40% high quality scrap. The high DRI charge rate limits the feasibility of fuel injection. The best practice excludes scrap preheating, although this is used in large scale furnaces.

The best practice DRI-scrap-fed EAF consumes a mix of 60% DRI and 40% scrap. It consumes 530 kWh/t (65 kgce/t) liquid steel for the EAF and 65 kWh/t(8 kgce/t) liquid steel for gas cleaning and ladle refining, as well as 8 kg/t liquid steel of carbon. Installing a scrap preheater reduces power use in the EAF by 40 kWh/t (4.9 kgce/t) liquid steel, reducing total electricity use to 555 kWh/t (68.2 kgce/t) liquid steel.

9.7.4 Scrap - Electric Arc Furnace Route

In the EAF steelmaking process, the coke production, pig iron production, and steel production steps are omitted, resulting in much lower energy consumption. To produce EAF steel, scrap is melted and refined, using a strong electric current. Several process variations exist, using either AC or DC currents and fuels can be injected to reduce electricity use.

303302

The EAF is equipped with eccentric bottom tapping, ultra high power transformers, oxygen blowing, full foamy slag operation, oxy-fuel burners, and carbon injection.

The "best practice" DRI-scrap-fed EAF consumes 100% scrap. It consumes 409 kWh/t (50.3 kgce/t) liquid steel for the EAF and 65 kWh/t (8 kgce/t) liquid steel for gas cleaning and ladle refining, as well as 0.15 GJ/t (5.1 kgce/t) liquid steel of natural gas and 8 kg/t liquid steel of carbon. Installing a scrap preheater would reduce power use in the EAF by 70 kWh/t (8.6 kgce/t), reducing total electricity use to 404 kWh/t (49.6 kgce/t) liquid steel.

9.7.5 Casting

Casting can be either continuous casting or thin slab/near net shape casting. Best practice continuous casting uses 0.06 GJ/t (2.0 kgce/t) steel of final energy. Energy is only used to dry and preheat the ladles, heat the tundish, and for motors to drive the casting equipment. Thin slab/near net shape casting is a more advanced casting technique which reduces the need for hot rolling because products are initially cast closer to their final shape using a simplified rolling strand positioned behind the caster's reheating tunnel furnace, eliminating the need for a separate hot rolling mill. Final energy used for casting and rolling using thin slab casting is 0.20 GJ/t (6.9 kgce/t) steel.

9.7.6 Rolling & Finishing

Hot Rolling

Rolling of the cast steel begins in the hot rolling mill where the steel is heated and passed through heavy roller sections to reduce the thickness. Best practice values for hot rolling are 1.55 GJ/t (53.0 kgce/t), 1.75 GJ/t (59.6 kgce/t), and 1.98 GJ/t (67.5 kgce/t) of steel of final energy for rolling strip, bars, and wire, respectively.

The best practice values assume 100% cold charging, a walking beam furnace with furnace controls and energy efficient burners, and efficient motors. Hot charging and premium efficiency motors may further reduce the rolling mill energy use.

Cold Rolling

The hot rolled sheets may be further reduced in thickness by cold rolling. The coils are first treated in a pickling line followed by treatment in a tandem mill. The best practice final energy intensity for cold rolling is 0.09 GJ/t (3.0 kgce/t) steam, fuel use of 0.053 GJ/t (1.8 kgce/t) and electricity use of 87 kWh/t (10.7 kgce/t) cold rolled sheet, equivalent to 0.47 GJ/t (13.7 kgce/t) cold sheet.

Finishing

Finishing is the final production step, and may include different processes such as annealing and surface treatment. The best practice final energy intensity for batch annealing is steam use of 0.173 GJ/t, fuel use of 0.9 GJ/t and 35 kWh/t of electricity, equivalent to 1.2 GJ/t (41.0 kgce/t). Best practice energy use for continuous annealing is assumed to be equal to fuel use of 0.73 GJ/t, steam use of 0.26 GJ/t, and electricity use of 35 kWh/t, equivalent to final energy use of 1.1 GJ/t (or 38.1 kgce/t). Continuous annealing is considered the state-of-the-art technology, and therefore assumed to be best practice technology.

While the data describes best practices in energy efficiency for key processes, the integration of these individual technologies is key to obtain the full benefits of these technologies. For example, combined heat and power would increase the efficiency of steam supply for the described processes, while by-product energy flows may also be used more efficiently by implementing more efficient technologies (e.g. use of blast-furnace gas in a combined cycle instead of a boiler). Tables 9.6 and 9.7 below summarize the Energy Intensity Values of the Best Plants based on International Iron & Steel Institutes (IISI) Eco Tech Plant & All Tech plants in U.S.

Table 9. 6 : Summary of World Best Practice "Final Energy Intensity Values" for Iron & Steel Sector

(Source : LBNL; Environment Technologies Division; Feb'2008 by Worrell E., Price L., Neelis M., Galitsky C., Nan Z.)

9.8 World's Best Practices of Energy Efficiency

Some important measures of energy conversation in different processes taken by Steel Industry Internationally are highlighted in this section.

Source : LBNL; Environment Technologies Division; Feb'2008 by WorrellE., Price L., Neelis M., Galitsky C., Nan Z.)

Table 7 : Summary of World Best Practice “Primary Energy Intensity Values” for Iron & Steel Sector

Unit GJ/t kgce/t

Technological Process

Blast Furnace – Basic Oxygen Furnace – Thin Slab Casting steel 16.3 555.1

Smelt Reduction – Basic Oxygen Furnace – Thin Slab Casting

steel

19.2 656.8

Direct Reduced Iron – Electric Arc Furnace – Thin Slab Casting

steel

18.6 635.8

Scrap - Electric Arc Furnace – Thin Slab Casting

steel

6.0 205.1

Iron and Steel

Unit GJ/t kgce/tIron and Steel

Technological Process

Blast Furnace – Basic Oxygen Furnace –Thin Slab CastingSlab Casting

steel

14.8 504.5

Smelt Reduction – Basic Oxygen Furnace – Thin Slab Casting

steel

17.8 606.4

Direct Reduced Iron – Electric Arc Furnace – Thin Slab Casting

steel 16.9 576.2

Scrap - Electric Arc Furnace – Thin Slab Casting steel 2.6 87.5

305304

• Sintering process

• Heat recovery from hot pallets is utilized to generate low temperaturesteam, which is used in turbo blower.

• Waste heat is recovered from cooler boiler• VFD is used for speed control of dust collecting blower and boiler water

feed pump• Steam vapour is used for preheating the sinter.• Complete heat balance is done in the sintering process.

• Coking process

• Coal is converted to coke by nitrogen injection process• Coke dry quenching (CDQ) is done and the steam and CO gas is

recovered.• Moisture in coke is controlled by tube type dryer utilizing low temperature

steam recovered in CDQ. • Sensible heat of gas (CO) recovered from CDQ is used to generate steam,

which is used in turbo - blower or moisture control equipment.• Moisture is reduced from 8% - 10% to 5% - 7% to increase the density.

About 5°C difference moisture control in coal increases the productivitydirectly by +5%.

• Exhaust gas heat is recovered from coke oven.• Complete heat balance of coke oven is done.

• Blast furnace and Iron making process

• Electric power conservation of dust collector and blower by use of VFD.• High temperature and pressure of dust collector is used for generating

power by top gas pressure recovery turbine (TRT).• Waste heat is recovered from hot stove and it is used for heating

combustion air.• Granulated slag waste heat recovery is done.• Reuse of dust as raw material in blast furnace (reduction in energy

consumption in 0.4%).• Prevention of molten iron temperature drop by using torpedo car.• Complete heat balance of blast furnace and hot stove is done.

• DRI Process

• Optimization of fixed carbon / iron (C/Fe) in the range of 0.40 -0.42.• Consistency in ash percentage of coal.• Modification of equipments and reduction in motor rating.• Optimization of operating parameters.• Use Proper capacity shell air fan. • Control in Carbon percentage in char (By-product) by efficient

combustion.• Control of Carbon % in fly ash through better combustion in After Burning

Chamber.• Effective, Efficient & Close monitoring of operating parameters.

• Steel Melting Process

• Exhaust gas heat recovery from torpedo car and ladle.• Heat recovery from converter slag.• LD Converter Gas (Linz and Donawitz) sensible heat recovery.

• Gas recovery from converter is done. • Continuous casting instead of ingots (transport without re-heating).

• Rolling Process

• In re-heating furnace, the following are energy conservation measures:• Extraction of slab at low temperature.• Improvement of heat pattern• Computer aided furnace temperature control.• Proper upkeep of recuperator• Improvement of heat transfer through proper design• Optimisation of combustion air fan capacity• Hot direct rolling through continuous casting• Complete heat balance of reheating furnace

• In hot rolling process, the following energy conservation measures are adopted:

• Increase productivity by improvement of coiler and strip cooling• Replacement of plunger pump (de-scaling pump).• Waste water heat recovery

• In cold rolling process, the following energy conservation measures are adopted:

• Optimisation of motor cooling fan capacity• Replacement of plunge pump (de-scaling pump).

• In annealing process, the following energy conservation measures are taken:

• Air and fuel preheating• Continuous annealing and process line.

307306

9.9 Energy Efficient Technologies being used in Iron & Steel Industry in Japan

Case Studies for different sections are given below for different areas of Iron & Steel Production to finishing and general utilities including Centralized Power Plant (CPP) in an integrated Iron & Steel Plant.

9.9.1 Case Studies in Iron Making Area

Case Study 1 : Coal drying and humidity control equipment for coke oven

Brief

It is the equipment which reduces the humidity in the coal to be charged into a coke oven by heating in order to reduce fuel consumption in the coke oven. It reduces the heat consumption for carbonization and utilises a large amount of non-coking coal.

The charging amount of coal in a coke chamber is increased, and coke quality is improved by the increased density of coal charging.

Productivity is increased by about 5.9% when the water content is reduced by 2.9%.

Fuel consumption in the coke oven is reduced by heating the coal and reducing the humidity. Mainly, steam is used for heating coal.

Energy Saving

Energy saving: 40,000-80,000 kcal/t-coal (18,000 kcal/t-coal per 1% of water-content reduction).Investment amount : Rs 800 Million for charge coal of 3,200 kt/yearAnnual Savings : Rs 400 MillionPayback Period : 2 years

Case Study 2 : Coke Dry Quenching (CDQ)

Brief

This improvement is to use equipment which cools red hot coke produced in a coke oven by exchanging heat with inert gas in a sealed vessel, and recovers the heat as steam or electricity.Coke production consumes 7-8% of the whole energy consumed in an integrated steel plant. About 45% of it is the sensible heat of red heat cokes coming out of coke ovens. Conventionally the red heat cokes which have the temperature of 1,000-1,200°C, are cooled by water spray, and the sensible heat is dissipated into the atmosphere. Coke dry quenching is to recover this waste heat by performing heat exchange with inert gas such as combustion exhaust gas in a sealed vessel, heating the gas to about 800°C, and generate steam by a boiler

Before improvement After improvement

Reduction of energy consumption kcal/T pig

Base 3291 x 10

Before Improvement After Improvement

Water Content in coal 7% - 11% 6%

The summary of the technological ENCON measures is diagrammatically shown in Fig. 9.1 below

Figure 1 : Iron & Steel : Production Process and Energy Saving Technology Source : Directory of Energy Conservation Technology in Japan: ECCJ)

Iron making process Steel making process Rolling Process

Technology

Improvement in segregated charging of sintering materials.

Coal drying and moisture control equipment for coke oven.

Coke dry quenching

Exhaust heat recovery system for sintered ore cooling equipment.

Sensible heat recovery from main exhaust gas of sintering machine.

Automatic combustion control of coke oven.

Blast furnace operation control system.

Blast furnace hot blast valve

control system.

Blast furnace burden distribution control.

Technology Pulverized coal injection for blast furnace. BF top – pressure recovery turbine.

Technology

DC arc furnace with water cooled furnace wall.

Continuous casting machine.

High frequency melting furnace.

Channel induction furnace for cast iron melting.

Ferroalloy furnace for effective energy utilization.

Hot stove exhaust heat recovery equipment.

BOF exhaust gas recovery device (including sealed BOF)

BOF gas sensible heat recovery apparatus.

Raw material preheater for electric arc furnace.

Heating furnace with regenerative burners.

Ladle heating apparatus with regenerative burners.

Energy saving operation of electric arc furnace.

Technology Hot charging and direct rolling mill. Channel induction furnace for cast iron melting. Ferroalloy furnace for effective energy utilization. Heating furnace with regenerative burners. High performance heating furnace. Recovery of sensible heat from skid cooling water in heating furnace. Descaling pump (conversion to plunger pump) Operation Improvement of heat treatment furnace.

Technology Continuous annealing line. Convection heating type heat treatment furnace for wire rod coil. Low temperature forge welded pipe production method. High efficiency gas separation apparatus. Centralized energy management. (Energy centre)

309308

(Specification: Coke treating capacity 150t/h, Coke temperature 1200°C, boiler efficiency 80%, BF coke ratio 480kg/t-pig)

Energy Saving

Investment amount : Rs 2.3 BillionAnnual Savings : Rs 0.813 BillionPayback period : 3 years

Case Study 3 : Automatic combustion control of coke oven

Brief

Program heating adjusts and optimizes the heating condition in each coking chamber in accordance with the state of coal carbonization. It saves energy by reducing coking energy consumption. It also improves the coke quality.

1) Measurements are carried out on the flue temperature, generated gastemperature, red-heat coke temperature, exhaust gas composition, etc.

2) Electric valve controllers are installed on each of the existing adjusting cocks at the branches of the gas and air distribution piping, and the drafting pressure regulating waist dampers.

3) Combustion in each chamber is separately controlled in accordance with the conditions of the charged coal (charged volume, moisture content, etc.) and the operation (target time to finish heating, etc.).

4) The operation control system is integrated, which covers heating pattern control, air-fuel ratio control, program heating, charge scheduling, etc.

Energy Saving

Amount of carbonization energy reduced: 40,000 kcal/ t-coal at coke production of 1,500 kt/ year.

Investment amount : Rs 160 MillionAnnual Saving : Rs 60 MillionPayback period : 3 years

Case study 4 : Exhaust heat recovery system for sintered ore cooling equipment

Brief

In this, the red-heat sintered ore, just after sintering, is air- cooled in the cooler. Sensible heat of hot exhaust gas from the cooler is recovered.

Sintered ore discharged from the sintering machine has the temperature of 500- 750°C, and cannot be transported directly to the blast furnace. Therefore, the air-cooling-type cooler is installed at the exit of the sintering machine. The sensible heat of the high-temperature part (250 - 450°C) of the cooler exhaust gas is recovered as steam. The power generation system using low-volatile flon-based medium (florinol) has been developed and put to practical use.

Energy Saving

Reduction in crude oil equivalent : 3,500 (kL/y) Reduction in calorific value : 60,000 kcal/t-sinter

Investment amount : Rs 800 Million Annual Saving : Rs 200 MillionPayback period : 4 years

Case Study 5 : Sensible heat recovery from main exhaust gas of sintering machine

Brief

In a sintering machine, fine iron ore is mixed with fine coke, powdered limese, etc., heated, and agglomerated into sintered ore, which is used as a blast furnace raw material. In this improvement, the main exhaust gas heat recovery and circulation process was adopted in addition to the cooler exhaust heat recovery. The main exhaust gas, which was previously dissipated into the atmosphere once its heat was recovered, is now returned back to the sintering machine, further enhancing the heat recovery efficiency.

In this process, using the waste heat boiler, the heat is recovered from the gas of the temperature of about 380°C exhausted from the sintering machine, and then the gas is returned back to the sintering machine. By this method, the heat recovery is increased by about 30% and at the same time, emission of NOx, SOx, etc., into the atmosphere is reduced.

Energy Saving

Reduction in crude oil equivalent: 8,430 kL/y Reduction of 30,000 kcal/t-sinter at sinter production of 2,600,000 t/year.

Investment amount : Rs 160 MillionAnnual Saving : Rs 60 MillionPayback period : 3 yearsSteam generation from boiler is 10 t/h

Case Study 6 : Improvement in segregated charging of sintering materials

Brief

This is an improvement of the charging device in the sintering process. By uniformly charging the materials along the width of the sinter bed and optimizing the size segregation along the height, the yield and quality are improved, resulting in energy saving.

The improvement of segregated charging is to optimize the size distribution along the height of the sinter bed.

By this, the permeability increases, and the quality of the sintered ores in the upper layer is improved, resulting in the overall yield improvement.Further, the return ores are reduced. Accordingly, the coke consumption is reduced and the energy saving effect is achieved.

Energy Saving

Before improvement After improvement Crude oil equivalent

Specific coke consumption (kg/T-sinter)

Base (-) 2.8 6,600 kL/y

Coal addition rate (%) Base (-) 0.54 1,200 kL/y

311310

Investment amount : Rs 75 MillionAnnual Saving : Rs 40 Million Payback period : 2 years

Case Study 7 : Pulverised Coal Injection (PCI) system for blast furnace:

Brief

This is a technology to inject pulverized coal directly into a blast furnace through tuyeres in place of using coke. Energy to produce cokes (coking energy) is reduced.

• Pulverized coal is injected into a blast furnace through tuyeres by a pulverized coal injection device.

• The type, size, etc. of pulverized coal injected differs by injection device and blast furnace.

• By improving the equipment and operation technology, injection of 50-200 kg/t-pig is now possible, resulting in a large energy saving.

Energy Saving

At the pig iron production of 3,000 kt/year,Reduction in crude oil equivalent: 19,460 kL/year at pulverized coal injection of 100 kg/t-pig, plus longer coke-oven life.Reduction of energy consumption per tonne of pulverized coal: 600,000 kcal/t-coal, coal injection 300,000 t-coal/yearInvestment amount : Rs 1.25 BillionAnnual Saving : Rs 0.4 BillionPayback period : 3.1 years

Case Study 8: BF Top-Pressure Recovery Turbine (TRT)

Brief

A device which utilizes the furnace top gas pressure of a high pressure blast furnace for generating electric power by driving gas turbine.

2 The pressure of the BF gas (B gas) generated in a blast furnace is 2-3kg/cm at the furnace top in high-pressure operation. In order to effectively utilize this gas in the downstream processes, conventionally its pressure was reduced by the septum valve after the dust was removed.

A top-pressure recovery turbine (TRT) utilizes this pressure and temperature, and recovers them as electricity by a gas turbine.

Energy Saving

Reduction in crude oil equivalent:29,000 - 39,000 kL/y at power generation of 18 MW and hot metal production of 3,000 kt/y, wet type.Investment amount : Rs 600 MillionAnnual Saving : Rs 360 MillionPayback period : 1.7 years

Case Study 9 : Hot stove exhaust heat recovery equipment

Brief

This is the equipment which improves the combustion heat efficiency and saves

energy by preheating combustion air and fuel gas for a blast-furnace hot stove by utilizing the sensible heat of combustion waste gas exhausted from the hot stove.

1) There are two types: one has separate heat exchangers for heat receiving and heat radiating, and heat medium is forced to circulate between the two; the other uses a regenerative heat exchanger and directly preheats combustion air

2) When preheating fuel gas, the type which has the heat exchangers completely separated is advantageous in view of safety, because fuel gas does not come in contact with high-temperature gas, and there is no danger of explosion.

Energy Saving

Reduction in crude oil equivalent : 9,700 kL/yReduction of 30,000 kcal/s-t at crude steel production of 3,000 kt/y(40 - 50% of the sensible heat of waste gas is recovered)Investment amount : Rs 200 MillionAnnual Saving : Rs 70 MillionPayback period : 3 years

Case Study 10 : Blast furnace hot blast valve control system

Brief

To improve the circumferential balance, hot blast control valves and their control system were adopted to individually control the hot blast flow rate at each of the tuyeres, hence saving energy.

The continuous control in accordance with the furnace condition was done with the help of hot blast control valves. Also, change in the fuel rate injection could be made possible.

Energy Saving

Energy saving : 134,000 kcal/t For Production Reduction in crude oil equivalent : 4,300 kL/y 3000 kt/y.Reduction in SOx, NOx : 47% Investment amount : Rs 80 MillionAnnual Saving : Rs 20 MillionPayback period : 4 years

9.9.2 Case Studies in Steel Making Area

Case Study 11 : Continuous Casting Machine

Brief

The continuous casting machine achieves large energy saving by eliminating some of the process steps. Molten steel is continuously charged into the mold. It is control-cooled from outside, and withdrawn as it is solidified from the surface and formed into semis. This machine eliminates the ingot casting, soaking, and slab or billet rolling, and achieves large reduction in fuel and power consumption.

]

313312

Energy Saving

Reduction in crude oil equivalent : 25,940 kL/y Reduction of 200,000 kL/t-steel at production of 1,200,000 t/year.Investment : Rs. 32.5 Million for casting capacity of

1,200,000 t/year Annual Saving : Rs 203 Million by energy saving and

Rs 813 Million by yield improvementPayback period : 2 months

Case Study 12: High frequency melting furnace

Brief

1) Frequency and power are selected, and the high frequency induction current,with enhanced current density which is 2 ~ 5 times higher than that of the lowfrequency method, is generated. This current generates heat by internal resistance of the material, and performs melting.

2) Steel and alloy steel are melted by the resistant heat generated by the induction current that flows in the steel itself.

3) Nonferrous metals and nonmetals are heated and melted by the conduction heat from the induction heating element such as graphite and metallic crucibles.

Energy Saving

Comparison of High-frequency and low-frequency melting furnaces

Investment amount : Rs 40 MillionAnnual Saving : Rs 4 Million year by energy saving and Rs 8

Million by quality improvementPayback period : 3 – 4 years

Case Study 13 : BOF Exhaust gas recovery device (including sealed BOF)

Brief

Exhaust gas generated during a BOF (Basic Oxygen Furnace) refining process is high-temperature gas containing mainly CO. A large volume of gas is generated intermittently. Energy of BOF exhaust gas is recovered and utilized.

1)For cooling and dust removing of BOF gas, there are two types of systems:combustion type (full-boiler type, half-boiler type) and non-combustiontype (OG type) In the past, the combustion-type gas recovery system was the mainstream. At present, the non-combustion type recovery system ismainly used due to the fact that small-sized facilities can cope with BOFs

Furnace capacity: 3t Low-frequencyMelting

furnace

High-frequencyMelting

Furnace

Energy-saving effect

Specific consumption

(kWh/t)719

630

12.3%

Melting speed (kg/h) 910 1550 Total production of a plant:Increase by 19.5%

Electricity (kW)

750

1500

Annual Electricity savings : Rs 3.6 Million

which are getting larger and it can collect the combustion gas as well.2) The recovered gas has the CO content of more than 60% and the heating

3value of about 2,000 kcal/Nm . It can be used as the fuel for boilers, rolling mills, and power generation plants.

3) Recently, the sealed-type OG method has been developed and is getting widely used, where the section between the furnace throat and the skirt is sealed during refining, in order to reduce the recovery loss of BOF gas.

It has following advantages compared with the combustion-type exhaust gas treatment method:

a) It is compact.b) The construction cost is low.c) The operation cost is low.b) The efficiency of dust collection from the exhaust gas is high.c) Recovered gas can be used as a clean fuel of a negligible sulfur content.

Energy Saving

Recovered energy from BOF exhaust gas is 2,00, 000 - 2,70,000 kCal per tonne of crude steel. The increased amount of BOF exhaust gas recovery by the sealed-type OG method is about 20,000 kcal per tonne of crude steel.

Investment amount : Rs 800 Million ( BOF capacity 250 t/h)The investment per unit BOF capacity (t/charge) is Rs 4 Million.

Case Study 14 : Ladle heating apparatus with Regenerative burners

Brief

Large Energy is saved by incorporating Regenerative burners into the apparatus to heat the refractories of a ladle which receives molten steel. It also prolongs the life of the ladle refractories.

A Regenerative burner system comprises of a pair of burners which burn alternately for a determined time period and function as a exhaust duct while not burning. The heat of the high-temperature exhaust gas is stored in the regenerator installed just after the burner, and the stored heat is used for preheating the combustion air.

Energy Saving

6 Fuel saving of 56% corresponds to monthly consumption of 573 x 10 kcal. 6 Increase of electric power consumption by auxiliaries : 23.9 x 10 kcal per month.

Investment amount : Rs 10 MillionAnnual Saving : Rs 4 MillionPayback period : 2.5 years (excluding the refractory life extension)

BeforeImprovement

After

improvement

Remarks

Fuel consumption

during

heating

(Nm3 /h)

200

120

Fuel consumption during soaking (Nm3 /h)

200

70-80

Fuelsavingof 56%

Refractory life of ladles Base case 10% extension

315314

Case Study 15 : DC Arc Furnace with water cooled furnace wall

Brief

Large energy saving is achieved in an arc furnace which melts and refines ferrous materials such as steel scrap by changing its power source from the conventional 3-phase alternating current (AC) to the direct current (DC).

a. The largest advantage of the DC arc furnace over the 3-phase AC arc furnace is that it can melt the materials uniformly.

b. In the DC arc furnace, the metal is melted and agitated by the electric current flowing through it and the magnetic field.

c. By adopting the water-cooled furnace wall, high-efficiency operation is achievable

d. Furnace maintenance materials are reduced.

Energy Saving.

1) Reduction in Specific power consumption : 5-10%.2) Specific electrode consumption reduction : 40-50%.

Investment amount : Rs 400 MillionAnnual Saving : Rs 100 MillionPayback period : 4 years

Case Study 16 : Channel Induction Furnace for cast iron melting

Brief

Induction furnaces are two types: crucible type and channel type. The channel type is more widely used because of its higher overall heat efficiency. It can perform continuous operation and save energy. Energy saving can be achieved by conversion to channel type.

Energy Saving

Investment amount : Rs 40 MillionAnnual Saving : Rs 12 MillionPayback period : 4 years

Case Study 17 : Ferroalloy furnace for effective energy utilization

Brief

The electric furnace for smelting HC-FeCr (high-carbon ferrochromium) refines chromium ore using coke as a reducing agent. However, as the ratio of fine chromium ore increased in recent years, permeability in the electric furnace decreased, and specific consumption of electric power and coke increased. The system described here reduces energy consumption for producing HC-FeCr and recovers the combustible exhaust gas.

Before improvement (crucible-type)

After improvement (channel-

type)1. Power efficiency 60%

-

80%

95%

-

97%

2. Overall efficiency 55%

-

65%

75%

-

85%3. Specific power consumption High Low4. Need of heel Not needed Needed5. Intermittent operation

Arbitrarily

possible

Principally

2

shifts or continuous

operation

When fine chromium ore is agglomerated and calcined into pellets by the annular furnace and the pellets are charged to the electric furnace in place of fine chromium ore, permeability in the furnace increases, which increases the heat exchange rate among charged materials, and decreases specific power consumption. Exhaust gas from the furnace is used as a fuel of the burner for pellet calcination. Excess gas is converted into steam, and steam purchase from outside is reduced.

Energy Saving

Reduction in crude oil equivalent : 12,570 tonnes/y.When applied to 7 electric furnaces of more than 10,000 KVA each, reduction in crude oil equivalent is 87,990 tonnes/y.Investment amount : Rs 400 MillionAnnual saving : Rs 100 MillionPayback period : 4 years

Case Study 18 : Raw material preheater for Electric Arc furnace

Brief

In this system, the heat efficiency of the electric arc furnace is improved by utilizing the sensible heat of high-temperature exhaust gas from the electric furnace to preheat the scrap. Hence, its electric power consumption is reduced.

1) With the 1-power-source 2-furnace method, the furnace itself is used for preheating the scrap instead of a scrap-charging bucket. While one furnace melts charged material, the other preheats the scrap. Scrap is heated to a higher temperature than by bucket preheating.

2) With the shaft-furnace method, scrap is preheated in the shaft furnace installed above the furnace

Energy Saving

Reduction of specific power consumption : 60,000-80,000 kcal/t (20% of the total heat of the electric- furnace

exhaust gas is utilized.Electric power saving : 25-50 kwh/t-s Shortening of the steelmaking time : 5-8 min./chargeInvestment amount : Rs 400 MillionAnnual Saving : Rs 100 MillionPayback period : 4 years (in the case of a 150t/charge furnace )

9.9.3 Case Studies in Rolling / Finishing of Steel

Case Study 19: Hot Charging and direct rolling mill

Brief

High-temperature semi-finished materials (slab, bloom, or billet) just after continuous casting (CC) is charged into the heating furnace with the temperature maintained as high as possible, thus reducing the fuel consumption at the heating

Before improvement

After improvement

Exhaust Gas Temp. 500-1000°C 150-400°C

317316

furnace. Further, by improving the measures for preventing the temperature drop of the semis after CC, the semis are directly sent to the rolling mill without going through the heating furnace, eliminating the heating process and substantially reducing the fuel consumption.

Energy Saving

3Reduction in crude oil equivalent : 16,200 kL/t Reduction of 50x10 kcal/t by coupling direct rolling with hot charging at rolling of 3,000 kt/y.

Investment amount : Rs 200 MillionAnnual Saving : Rs 100 MillionPayback period : 2 years

Case Study 20 : Descaling pump (conversion to plunger pump)

Brief

A descaling pump is used to apply high – pressure water jet to remove the scale during steel rolling operation. In order to reduce power consumption, various measures were taken, such as pressure and flow rate reduction. To achieve further power saving, the turbine pump was converted to the plunger pump.

Since high-pressure jet is applied intermittently in short duration, a plunger pump, which can perform no-load operation at a low pressure, significantly saves power consumption during the time when high-pressure water jet is not applied.

Energy Saving

Investment amount : Rs 80 MillionAnnual saving : Rs 30 Million

2Investment payback : 2.5 years at 2750 L/min x 175 kg/cm x 1 unit

Case Study 21 : Convection heating type heat treatment furnace for wire rod coil

Brief

To shorten the time required for annealing of wire rod coils a forced circulation fan was installed. The outside of the wire rod coils is heated by the radiation from the radiant tube heat source as well as by the convection heat transfer by the forced circulation fan installed at the top cover. Hot air is forced into the inside of the coils by the fan. It passes through among the individual strands of the coils, and heats up the coils. Forced convection heat transfer by the fan improves the heat transfer efficiency, shortens the treatment time, and saves energy. At the time of cooling, an indirect gas cooler is employed for rapid cooling, instead of the radiant tubes.

Energy Saving

Heating time reduced by approx. 2.5 hours

Before

improvement After improvement

Savings/Improvement

Loaded 1930 kW 1890 kW 40 kWPower consumption Unloaded 1210 kW 180 kW 1030 kWAnnual energy consumption 9456 MWh/y 3948 MWh/y 5508 MWh/yReduction in crude oil equivalent 1,338 kl/y

Cooling time reduced by approx. 3 hoursFuel saving : 25%Investment amount : Rs 80 MillionAnnual saving : Rs 20 MillionPayback period : 4 years

Case Study 22 : Low temperature forge welded pipe production method

Brief

Electro-magnetic induction heating (an edge heater) was introduced in forge-welded pipe production, and the temperature of steel hoops at the exit of a continuous heating furnace was reduced from the previous high temperature (1300°C) to 1200°C, the edge being locally heated. Accordingly, specific fuel consumption of the heating furnace was reduced

1) The automatic control system is introduced to control the edge to the constant temperature (an electro- magnetic induction heating method).

2) A seam cooling device is installed to eliminate the temperature difference in the circumference direction of pipes. The prevention of beading and bending is made possible.

3) The forge welding roll in the mill has a motor driven screw down mechanism to control the forge welding stress.

Energy Saving

Reduction in crude oil equivalent : 7,500 kL/y3Reduction of energy consumption :115 x 10 kcal/t at the production of 50,000t/m.

Investment Amount : Rs 500 MillionAnnual Saving : Rs 160 MillionPayback period : 3.5 years

Case Study 23 : Energy saving operation of Electric Arc Furnace

Brief

An example of the operation improvement which targets at the reduction of electric power consumption of small and medium size electric arc furnaces is as follows :

1) Use of a basic melting furnace- Electric arc furnaces are divided into two types by the lining refractories they use: acidic furnace (MgO-based refractories) and basic furnace (SiO -2

refractories). The acidic furnace merits because of low power consumption and short melting time. On the other hand, it has a difficulty in removing harmful elements such as P and S, and therefore it has the limitation in the types of steel it can produce.- One of the furnaces was remodeled to an acidic type to deal with return scrap which contains relatively smaller amounts of P and S, and power saving was achieved.

2) Shortened melting time by eliminating intermediate analysis - Earlier, for the purpose of checking the compositional specification in the arc furnace, composition analyses were performed four times: at melt down, at oxidation finishing, at the intermediate time, and in the ladle. It was

319318

confirmed that the elimination of the intermediate analysis does not cause quality problems. The elimination shortened the melting time by about 5 minutes, and saved energy consumption by about 20 kWh/t.

Energy Saving

3 Annual energy consumption : 2,460 x 10 kwhAnnual Reduction in crude oil equivalent : 600 kL Investment amount : Rs 4 Million Annual Saving : Rs 4 MillionPayback period : 1 year

9.9.4 Case Studies in General Utilities and CPP

Case Study 24 : Heating furnace with Regenerative burners

Brief

A regenerative combustion system uses a pair of Regenerative burners, in each of which a burner for combustion and a regenerator for heat storing are incorporated. Each of the pair is used for combustion and heat storing alternately. It is a highly efficient combustion system which can recover more than 85% of the waste heat. A system is so constructed that one burner performs combustion and the exhaust gas from the combustion is led to the opposite side burner.

Energy Saving

Reduction of specific fuel consumption : 10-30%.Investment amount : Rs 12 Million per pair of burnersAnnual Saving : Rs 4 MillionPayback period : 3 years

3 Combustion volume : 5,000 x 10 kCal/piece

Case Studies 25 : Recovery of sensible heat from skid cooling water in heating furnace

Brief

Skid beams in a heating furnace are cooled by passing water through their insides. Previously the cooling water was sent to a cooling tower and circulated. This improvement is to supply pure water as cooling water in place of previous industrial

2water, and recover the heat as steam of 12 kg/cm .

The inner temperature of the furnace is about 1300°C. Skid beams are used as heat transfer tubes of a boiler. A steam – water separation drum is installed outside the furnace, where steam is generated, recovering the heat.

Energy Saving

2Recovery amount of steam : 9 t/h x 12 kg/cmAnnual Recovered heat in crude oil equivalent: 23,000 kL at operation of 7900 tonneInvestment amount : Rs 750 MillionAnnual Saving : Rs 280 MillionPayback period : 3 years

Case Study 26 : Control of excess air by installing O monitoring system in high- 2

pressure boiler of CPP in a steel plant.

Brief

Presently, there is no monitoring of O in flue gases of this boiler, which is used, in 2

captive power plant of steel plant. Without this, optimization of efficiency of boilers is not possible, especially when quality of coal and boiler load is also changing.

By continuous monitoring & controlling the excess air & maintaining the % O 2

below 6%, the efficiency of boiler can be improved from 79.1% to 83.5%. Further improvement of boiler efficiency is possible by taking care of the unburnt carbon in ash.

Energy Saving

The following table summarizes the overall effect of O monitoring & control effect 2

on boiler performance :

Annual hours of operation HP-1 boiler = 4350 hours Average steam generation = 73.6 TPH (average during trials)Annual saving in fuel input =Steam flow x Enthalpy of steam x 1 - 1 x Annual operating hoursGCV of coal Eff Eff 1 2

Where Eff = Existing efficiency of boiler, Eff = Likely efficiency of boiler after 1 2

modifications in control

Annual saving in coal = 73.6 x 639 x (1/0.79 – 1/0.84) x 4350 tonne 3825

= 3563 tonnes(Price of Coal : Rs. 1000 per tonne)

Annual Saving : Rs 3563 x 1000 = 3.56 MillionInvestment amount : Rs 0.5 MillionPayback period : 2 month

Case Study 27 : Use of variable frequency drives on FD fans and ID fans in place of existing inlet

Brief

It was recommended to install VFDs in FD & ID fans for energy saving. After implementing the O monitoring system as explained above, the following 2

operating parameters observed on FD and ID fans on boiler – 1 are given below :

Parameter

Existing condition

After installing O2

monitoring & control system

%O2 13.7 6 Excess air, % 189.6 40 Boiler efficiency, % 79.1 83.5 FD Fan airflow, Nm 3 /h 264607 127558 ID fan airflow, Nm 3/h 317528 153069

( )

321320

Energy Saving

Assuming 25% time operating each at 60%, 70%, 80% and 90% of rated flow, energy savings are calculated as shown below:

Annual Saving per fan= 2,20,000 kWh/ year : Rs 0.55 Million Total energy cost saving for 4 nos. fans : Rs 2.2 MillionInvestment : Rs 6 Million ( for 4 nos. motors):Payback period : 3 years

Case Study 28: Reduction of number of stages of pump from existing 7 stages to 5 nos. stages

Brief

By reducing the number of stages of feed pumps (2 nos) from 7 stages to 5 stages, 2there will be a drop of head by 30 kg/cm , which is still higher than the rated one by

15 %. This will reduce the power by about 400 kw.

Energy Saving

Annual Saving : 32,00,000 KWh (at 8000 hrs. operation)Annual monetary saving : Rs 8 MillionInvestment amount : Rs 1.2 MillionPayback period : 1 month

Case Study 29 : Installation of appropriate/ smaller capacity CW pumps in CPP of steel plant

Brief

At present, the throttling valves are used to throttle the flow upto 50 %. By installing the pumps of smaller capacity, a lot of power can be saved.

Before

improvement

After

improvement

No. of stages of pumps

7

5

Head (mwc) 750 450

Power input (kw) 1900 1500 Pump efficiency (%) 72 72 3Flow (m /h)

490

490

Before

improvement

After

improvement

Rating of FD fans kw)

275x2

250x2

Rating of ID fans (kw) 310x2 250x2

FD fan air flow (Nm3/h) 264607 127558

ID fan air flow (Nm3/h)

317528

153069

Particulars TG-4 TG-5

Cooling water flow rate at present (combined for two pumps)

35340 m / hr

35188 m / hr

Design cooling water flow requirement for condensers

36800 m /hr 36800 m /hr

Rated flow rate of the proposed individual pump

33500 m / hr 33500 m /hr

Combined efficiency of the proposed pump/ motor

70% 70%

Estimated power drawn by each pump

327 kW (654 kW for two pumps)

327 kW (654 kW for two pumps)

Actual power drawn by two pumps at present 725 kW 700 kW

Reduction in the power drawn 71 kW 46 kW

Energy Saving

Annual energy saving : 93,6000 kWhAnnual Saving : Rs 1.872 MillionInvestment amount : Rs 1.5 MillionPayback period : 10 months

References

1. IEA, World Energy Outlook 2007.2. International Iron & Steel Institute Brussels Statistical Handbook.3. Directory of Energy Conservation Technology in Japan, prepared by New

Energy & Industrial Technology Development Organization, The Energy Conservation Centre, Japan.

4. Annual Report of Ministry of Steel, 2007-08, GoI.5. The Energy Data Directory Yearbook, TEDDY, 2007.6. World Best Practice Energy Intensity Values for Selected Industrial Sectors

(Ernest Orlando Lawrence Berkeley National Laboratory), Environmental Energy Technologies Division; by Ernst Worrell, Lynn Price, Maarten Neelis, Christina Galitsky & Zhon Nan.

7. Energy Use & Carbon Dioxide Emissions in Steel Sector in Key Developing Countries by Lynn Price, Dian Phylispsen, Ernst Worrell; Energy Analysis Dept., Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory.

8. International Iron & Steel Institute (IISI) Brussels-Energy use in Steel Industry.

9. Future Technologies for Energy-Efficient Iron & Steel Making-Annual Review of Energy & Environment.

10.Alternate Iron making update- Iron & Steelmaker; by Mc Aloon T.P.11. National Commission on Energy Policy report

www.energycommission.org/.12.Potentials for Improved use of Industrial Energy & Materials ; Thesis

Ph.D, Utrecht Univ.13.Emerging Energy Efficient Technologies; Worrell E., Price L., Galitsky C.14.The Steel Industry in India-Iron making & Steel making; by Chatterjee A.15.Handbook of Energy Conservation (Vol-2) by H.M. Robert & J.H. Collins16.websites : www. worldsteel.org/steeldatacentre/countries 1998.htm

www.worldsteel.org/steeldatacentre/lgcountry.htm.

323

Notes Chapter - 10

Fertilizer

10.1 Introduction

The Indian fertilizer industry made a very humble beginning in 1906, when the first manufacturing unit of Single Super Phosphate (SSP) was set up in Ranipet near Chennai with an annual capacity of 6000 Tonnes of Rock Phosphate (P O ). The 2 5

Fertilizer & Chemicals Travancore of India Ltd. (FACT) at Cochin in Kerala and the Fertilizers Corporation of India (FCI) in Sindri in Bihar (now Jharkhand) were the first large sized fertilizer plants set up in the forties and fifties with a view to establish an industrial base to achieve self-sufficiency in food grains. Subsequently, the Green Revolution in the late sixties gave an impetus to the growth of fertilizer industry in India and the seventies and eighties witnessed a significant addition to the fertilizer production capacity. However, there has not been any substantive addition to fertilizer production capacity during the last 15 years.

10.1.1 Production of Fertilizers

Production of Urea, which was 186 lakh Tonnes in 2002-03, increased to 201 lakh Tonnes in 2005-06 and further to a record level of 203 lakh Tonnes in 2006-07. Production of Diammonium phosphate (DAP), however, declined in 2006-07 at 47 lakh Tonnes after reaching a peak at 52 lakh Tonnes in 2002-03, mainly because of feedstock problems and shift of phosphatic capacity towards production of complexes. Decline in production of phosphatic fertilizers has been due to constraints in availability of phosphoric acid and high prices of sulphur. Requirement of Muriate of Potash (MOP) is met fully by imports. The production of Urea, DAP and complexes during the last five years and during the current year up to December 2007 are given below: -

Table 10.1

10.1.2 Installed Capacity

As on 31 March 08, the country has an installed capacity of 122.84 lakh Tonnes of nitrogen and 58.59 lakh Tonnes of Phosphate. Presently, there are 59 large size fertilizer plants operating in the country manufacturing a wide range of nitrogenous, phosphatic and complex fertilizers. Out of these, 31 (as on date 28 are functioning) units produce urea, 19 units produce DAP and complex fertilizers, 2 units produce Calcium Ammonium Nitrate (CAN) & Ammonium Chloride and the remaining 10 units manufacture ammonium suplhate as product. Besides, there are about 78 medium and small- scale units in operation producing SSP. The sector - wise installed capacity is given in the table below: -

(In lakh Tonnes)

Source: FAI and Department of Chemicals & Fertilizers

Product 2002- 03 2003–04 2004-05 2005-06 2006-07 2007-08 Urea 186.21 190.38 202.39 200.85 202.71 198.39 DAP 52.36 47.09 51.72 45.54 47.13 42.11 Complexes 48.61 45.07 52.59 67.65 73.13 58.33

325324

Table 10.2

Sector-wise & Nutrient - wise Installed Capacity Of Fertilizer Manufacturing Units as on 31.03.2008

(In lakh Tonnes)

Source: FAI and Department of Chemicals & Fertilizers

10.1.3 Per Capita Consumption

The per capita consumption of fertilizer of agricultural population in India, which was a meager 1 kg in the early 50's, has increased substantially to about 32.7 kg in 2004-2005.

The per capita fertilizer consumption of agricultural population in different countries is highlighted in the table below:

Table 10.3

*of agricultural population ** of arable land and land under permanent crops

Source: FAI and CII-IREDA

10.2 Raw Material Profile

The basic raw materials for the production of fertilizers are ammonia for nitrogenous fertilizers, phosphate for straight phosphatic fertilizers, and potash for potassic fertilizers. Out of the three fertilizer types, production of ammonia is most energy and resources intensive.

10.2.1 Nitrogenous fertilizers

Domestic raw materials are available only for nitrogenous fertilizers. For the production of urea and other ammonia-based fertilizers, methane is the major input. Methane is obtained from natural gas/ associated gas, Naphtha, fuel oil, low sulfur heavy stock (LSHS) and coal. Of late, production has switched over to use of natural gas, associated gas and Naphtha as feedstock. Out of these, associated gas is most hydrogen rich and easiest to process, due to its lighter weight and fair abundance within the country. However, demand for gas is quite competitive since

SNo. Sector Nitrogenous Phosphatic Capacity % Share Capacity % Share 1 Public 35.92 29.24 3.87 6.60 2 Cooperative 31.69 25.80 17.13 29.24 3 Private 55.23 44.96 37.60 64.16

Total 122.84 100.00 58.59 100.00

Country Fertilizer Consumption(kg Per capita)*

Fertilizer Consumption(kg/ha)**

India 32.7 108.4China 52.9 289.1Japan 438.9 363.0Egypt 78.4 555.1Bangaladesh 23.1 197.6

Pakistan 42.7 146.2

France 2492.0 210.5 Russian Federation 131.8 14.4 UK 1814.7 305.2USA 3463.0 113.5 World 59.7 101.0

it serves as a major input to electricity generation and provides the preferred fuel input to many other industrial processes.

10.2.2 Phosphatic fertilizers

For production of phosphatic fertilizers, most of the raw materials have to be imported. India has no source of elemental sulfur, phosphoric acid and rock phosphate. Some low-grade rock phosphate is domestically mined and made available to rather small- scale single super phosphate fertilizer producers. Sulfur is produced as a by-product by some of the petroleum and steel industries.

10.2.3 Ammonia production

The most important step in producing ammonia (NH ) is the production of 3

hydrogen, which is followed by the reaction between hydrogen and nitrogen. A number of processes are available to produce hydrogen, differing primarily in type of feedstock used. The hydrogen production route predominantly used worldwide is steam reforming of natural gas. In this process, natural gas (CH ) is mixed with 4

water (steam) and air to produce hydrogen (H ), carbon monoxide (CO) and carbon 2

dioxide (CO ). Waste heat is used for preheating and steam production, and part of 2

the methane is burnt to generate the energy required to drive the reaction. CO is further converted to CO and H using the water gas shift reaction. After CO and 2 2

CO is removed from the gas mixture ammonia (NH ) is obtained by synthesis 2 3

reaction. Another route to produce ammonia is through partial oxidation. This process requires more energy (up to 40-50% more) and is more expensive than steam reforming. The advantage of partial oxidation is high feedstock flexibility; it can be used for any gaseous, liquid or solid hydrocarbon. In practice partial oxidation can be economically viable if used for conversion of relatively cheap raw materials like oil residues or coal. In the partial oxidation process, air is distilled to produce oxygen for the oxidation step. A mixture containing among others, H , CO, 2

CO and CH is formed. After desulfurization CO is converted to CO and H O. CO 2 4 2 2 2

is removed, and the gas mixture is washed with liquid nitrogen (obtained from the distillation of air). The nitrogen removes CO from the gas mixture and simultaneously provides the nitrogen required for the ammonia synthesis reaction.

10.3 Energy Profile

Production of nitrogenous fertilizers is highly energy intensive. Ammonia is used as the basic chemical in the production of nitrogenous fertilizer. Production of ammonia itself involves almost 80% of the energy consumption in the manufacturing processes of a variety of final fertiliser products. Therefore, ammonia is considered a key intermediate for determining the overall energy efficiency of fertiliser production. Besides air as the source of nitrogen, the ammonia-manufacturing process have choice of using raw materials such as water, natural gas, naphtha, fuel oil, coal, coke oven gas. Natural gas is the best feedstock for ammonia production. However, the use of natural gas in India for urea production is constrained due to its scarce availability.

Better feedstock and process technologies, together with improved operation and maintenance practices, retrofitting, and so on have resulted in significant amount of energy savings during ammonia production. The average specific energy consumption for ammonia production in India has improved significantly from 57.35 Giga Joules (GJ)/tonne in 1985-86 to 37.53 GJ/tonne in 2007-08. The average energy consumption of 25% of the most efficient Indian ammonia plants is 32.7GJ/tonne in 2007-08.

327326

10.3.1 Energy Intensity

The fertilizer industry is one of the major consumers of hydrocarbons. The fertilizer sector accounts for 8% of total fuels consumed in the manufacturing sector. Energy costs account for nearly 60 to 80% of the overall manufacturing cost. The absolute energy consumption by this sector has been estimated at 628 million GJ annually. The specific energy consumption per ton of urea varies between 21.59 GJ for the most efficiently operating plant to 52.38 GJ for the most inefficient plant during 2007-08. Energy intensity in India's fertilizer plants has decreased over time. This decrease is due to advances in process technology, better stream sizes of urea plants and increased capacity utilization.

Energy is consumed in the form of natural gas, associated gas, Naphtha, fuel oil, low sulfur heavy stock and coal for process. LDO, LSHS, HFO and HSD are also used in diesel generators. Large fertilizer plants generate part of their own power through cogeneration mode in Turbo Generator (TG) sets, while smaller plants depend exclusively on purchased power or power from DG sets. With the ever-increasing fuel prices and power tariffs, energy conservation is strongly pursued as one of the attractive options for improving the profitability in the Indian fertilizer industry.

The feedstock mix used for ammonia production has changed over the last decade. The choice of the feedstock is dependent on the availability of feedstock and the plant location.

The shares of feedstock's in ammonia production are as follows:

Source: FAI

The shift towards the increased use of natural/associated gas and Naphtha is beneficial as this feedstock is more efficient and less polluting than heavy fuels like fuel oil and coal.

The production of phosphatic fertilizer requires much less energy than nitrogenous fertilizer. Depending on the fertilizer product, energy consumption varied from negative input for sulfuric acid to around 1.64 GJ/tonne of fertilizer for phosphoric acid. For sulfuric acid the energy input is negative since more steam (in energy equivalents) is generated in waste heat boilers than is needed as an input.

10.3.2 Specific Energy Consumption (SEC)

Ammonia is the intermediate product in Urea production. Out of total energy consumed for the production of Urea, 80% is consumed in Ammonia production. Hence, efficient production of Ammonia has greatest impact on Specific Energy Consumption.

Table 10.4

Feedstock

Natural Gas

Naphtha

Fuel oil

1997-1998

60.4 %

21.2%

15.0%

2007-2008

78%

11%

11%

Energy Consumption (GJ/Tonne) Feedstock

Ammonia Urea

Gas 35.54 24.99 Naphtha 41.23 30.01 Fuel Oil 49.06 33.45 Total 37.55 26.33

Ammonia Urea

Feedstock based Plants

India Average (2001)

India Best (Improvement Potential)

World Average (1998)

World Best

China Average (2000)

Ammonia 36.5 30.3 TCL Babrala (17%)

36.6 28.0 36.7 Gas based plants

Urea 26.5 22.5 TCL Babrala (15%)

25.8 20.9 26.3

Ammonia 39.9 34 CFCL Kota (15%)

38.7 Naphtha based plants

Urea 29.1 24.3 CFCL Kota (16%)

28.3

Ammonia 58.4 47.9 GNFC (18%) Bharuch

FO based plants

Urea 40.5 31.3 GNFC (23%) Bharuch

Hence, efficient production of Ammonia has greatest impact on Specific Energy Consumption.

The specific energy consumption comparison of Indian fertilizer industry with the World and China is as follows:

Table 10.5(a)Specific Energy Consumption by Feedstock Type (GJ/tonne NH )3

Note: The urea figures include the embedded energy in the production of ammonia Source: LBNL

Table 10.5(b)Feedstock-wise Capacity and Energy Consumption in

Operating Ammonia Plants

Source: FAI

10.4 Potential for Energy Efficiency Improvement

The biggest drawback of the Indian fertilizer industry is its reliance on non-natural gas-based plants. If we consider only the natural gas based plants, Indian plants compare favorably with international practices (Table 10.5a). The figures in brackets are the improvement potentials if plants were to reach best practices available in India. The highest energy saving potential is observed with fuel oil based plants.

The best practice energy intensity worldwide is 28 GJ/Tonne of ammonia, and is a result of auto-thermal reforming technology process. Auto thermal reforming process is a mixture of partial oxidation and steam reforming technology. According to the European Fertilizer Manufacturing Association (EFMA), two plants of this kind are in operation and others are at the pilot stage.

Tata Chemicals owns and operates one of the more energy-efficient plants for the production of ammonia and urea in India with an energy intensity of 30.3 GJ/Tonne of ammonia and 22.5 GJ/Tonne of urea. These energy intensity values are among

329328

the lowest recorded internationally. Manufacturing facilities at Babrala comprise an ammonia plant of 1520 TPD and a urea plant of 2864 TPD capacity which were implemented and commissioned in December 1994. Even though the plant currently uses natural gas, it has been designed for full flexibility in the use of natural gas and naphtha as a feedstock and fuel.

When only natural gas-based plants are considered, India appears to maintain very competitive plants compared to the world average (Table 10.5a). However with latest changeover of number of plants from naphtha to natural gas, India has now 80% ammonia capacity based on natural gas as of 2007.

India's national average figures of specific energy consumption for ammonia plants are close to the world average but there is wide variation in energy consumption of various plants. It varies from 32 GJ/Tonne to 63 GJ/Tonne with a weighted average of 37.55 GJ/Tonne. This wide variation is mainly because of the operation of Naphtha & fuel based plants, which have higher energy consumption than gas-based plants. In a competitive environment, with energy cost representing between 60% to 80% of total production cost depending on the type of plant, companies will be compelled to gradually switch over to natural gas in order to have an energy consumption per ton of output closer to world average and become more competitive in the international market.

10.4.1 Categories of Energy Efficiency Improvement

Over the past 30 years, induced by major technological improvements and by a better energy management, the energy used to produce each ton of ammonia has declined by 30 to 50%. Technology-wise, three different process stages can be distinguished where energy improvements are possible:

Steam reforming phase: This is the most energy intensive operation, with the highest energy losses. Different methods are available to reduce losses that occur in the primary reformer, viz., installing a pre-reformer, shifting part of the primary reformer load to the secondary with installation of a purge gas recovery unit, and upgrading the catalyst to reduce the steam/carbon ratio. It is possible to reduce energy losses by 3-5 GJ/Tonne of NH .3

CO removal phase: The removal of CO from the synthesis gas stream is normally 2 2

based on scrubbing with a solvent. A reduction of the energy requirement for recycling and regeneration of the solvent can be achieved by using advanced solvents, pressure swing absorption or membranes. Energy savings are in the order of 1 GJ/Tonne of NH .3

Ammonia synthesis phase: A lower ammonia synthesis pressure reduces the requirement for compression power, and also reduces production yield. Less ammonia can be cooled out using cooling water so more refrigeration power is required. Also the recycling power increases, because larger gas volumes have to be handled. The overall energy demand reduction depends on the situation and varies from 0-0.5 GJ/Tonne of NH . Another type of catalyst is required to achieve the 3

lower synthesis pressure. Furthermore, adjustments have to be made to the power system and the recycle loop.

Additionally, energy price escalation and growing concerns regarding pollution have intensified the attention on energy conservation at all levels. Improving

energy efficiency does not necessarily require investment and can result from a better balancing of energy flow along the process. The optimization of operations and maintenance practices, by reducing waste heat and capturing excess heat to channel it back into the system, allows a better energy distribution and constitutes major energy efficiency improvements.

Some plants in India have realized considerable energy savings by increasing awareness at all levels in the plant, monitoring energy consumption during production, and identifying potential energy-savings opportunities

Some Technologies that can be adopted by fertilizer plants for energy efficiency improvement are briefly described below:

10.5 Technologies & Measures for Energy Efficiency Improvements

10.5.1 Haldor Topsoe Exchange Primary Reformer (HTER-p) (Ammonia Production)

Technology Description

HTER-p is introduced reforming section in ammonia plant to reduce size of the primary reformer and at the same time reduce the HP steam production. HTER-p is a new feature, initially developed for use in synthesis gas plants. In ammonia plants this is operated in parallel with the primary reformer, and that is why the name is HTER-p. The exit gas from the secondary reformer heats the HTER-p, and thereby the waste heat normally used for HP steam production can be used for the reforming

oprocess down to typically 750-850 C, depending upon actual requirements. The technology was implemented in a synthesis gas plant in South Africa in the year 2003.

Advantages

Operating conditions in the HTER-p are adjusted independently of the reformer in order to get the optimum performance of the primary overall reforming unit. In this way, up to around 20% of the natural gas feed can by-pass the primary reformer.

10.5.2 Uhde Dual Pressure Ammonia Technology (Ammonia Production)

Technology Description

At present, reducing the cost of plant by increasing the plant capacity is a major thrust in conventional ammonia process. To overcome the constraints in increasing the plant capacity beyond 2000 metric tons per day, Uhde has developed Dual Pressure technology. Dual Pressure process focuses on the de-bottlenecking of the conventional synthesis loop. A synthesis reactor has been introduced at an intermediate pressure level in the synthesis gas loop, which makes synthesis, and separation of ammonia possible in between compressor casing and the synthesis gas volume flow to the high-pressure loop is significantly reduced.

Advantages

The production can be raised by about 65%. Gives a superior hydrogen yield. Energy consumption is reduced by up to 4%. Cost of production is reduced by 10% to15%.

331330

10.5.3 Megammonia (Ammonia Production)

Technology Description

The Megammonia technology is designed in the year 2003 jointly by M/s Lurgi and M/s Ammonia Casale for large scale production capacity of 4000 TPD Ammonia. Using natural gas, steam and air as feedstock, following five principal steps as below produces ammonia:

i. Air separation: 95% oxygen and 99.99% pure nitrogen is produced from air.

ii. Catalytic Partial Oxidation: Desulphurised natural gas, after addition of steamis first preheated in a fired heater and then reformed over a nickel oxide catalystto CO, H and CO following partial oxidation. 2 2

iii. CO-Shift: Reformed gas is passed through two beds of conventional HT shiftcatalyst (Copper promoted Iron / chromia based) in series to convert remainingCO to H and CO .2 2

iv. Gas Purification: CO is removed by absorption in cold methanol and other2

impurities like CO, CH and Ar are removed by washing the gas with liquid4

nitrogen.

v. Ammonia Synthesis: The extremely high purity of ammonia synthesis gasresults in higher conversion of gas per pass, lower circulator duty and lowerrefrigeration duty.

Advantages

Reduction in the capital cost by 18-20%. Operating cost is expected to be lower around 12 -15% over the most advanced conventional technology. CO emission is 2

expected to reduce by around 30% as compared to other conventional technologies.

10.5.4 HydroMax Technology (Ammonia Production)

Technology Description

Alchemix Corporation U.S.A developed the Hydromax technology. The technology is used for production of hydrogen using either relatively cheaper coal or using inexpensive fuels like municipal waste, biomass and petroleum coke etc. in presence of metal like iron. The technology involves a two-step process. In the first step, steam reacts with molten iron to form iron oxide and hydrogen and in the second step, iron oxide is reduced back to pure metal by adding carbon. Iron simply acts as a carrier for oxygen. In both steps, hydrogen production and reduction of iron oxide back into iron occur in the same reactor at the same temperature of 1250°C.

Advantages

Carbon dioxide and hydrogen are produced in separate compartments and do not require CO removal system. Cost of production is almost four times less than Steam Methane 2

Reforming (SMR) production cost. Emission of greenhouse gases is 34% less than SMR process.

10.5.5 Feedstock conversion from Naphtha to Regassified Liquified Natural Gas (R-LNG) in Ammonia-Urea plants

Technology Description

The type of feedstock has a major influence on energy consumption in an Ammonia-Urea plant. Hydrogen to carbon ratio increases as we move from liquid hydrocarbons (Naphtha, FO, LSHS, etc.) to gaseous hydrocarbons (Natural Gas). Besides, associated impurities namely sulphur, etc. are present only in traces in the case of gas. With the steep rise in the cost of liquid hydrocarbons in the last five-to-six years, Ammonia- -Urea production from liquid hydrocarbons plants has become very costly. Most significant difference between Naphtha and Natural Gas based Ammonia plants are in the Desulphurization Section. Since gas does not contain much sulphur unlike in Naphtha, hence pre-desulphurization section need not be operated. Other important aspect is in the hydrogen to carbon ratio, which is high in case of gas. As a result, less steam is consumed in the reforming section and less CO 2

is generated. After the reforming section, plants operating on Naphtha or gas are identical except in the quantum of generation of CO .2

Advantages

Natural gas is ideal feedstock for ammonia production. It has several advantages besides being cheaper and easy to handle. It allows easy and shorter start up of the plant, thereby lesser unproductive consumption. The burners choking phenomena is completely solved and CO emission from furnace has reduced. Plant also runs 2

trouble free and the catalyst life is also increased

10.5.6 Carbon Dioxide Recovery (CDR) Plant

Technology Description

With the steep rise in the cost of liquid hydrocarbons, Ammonia -Urea production from liquid hydrocarbons plants has become very costly. As major disadvantage of RLNG conversion is lesser CO production due to lower C/H ratio in RLNG as 2

compared to Naphtha. CO generated with lean RLNG is not adequate to convert 2

total Ammonia produced to Urea. One of the possible options to overcome this problem is the recovery of CO from flue gas from various furnaces. CDR plant is 2

basically a low pressure CO removal section in which CO present in flue gases is 2 2

absorbed & then regenerated to produce CO having 99.93 % purity. CO recovery 2 2

from flue gases is a new concept in fertilizer industries.

Basic steps involved in CDR plant are:

a) Flue gas Pretreatmentb) Low pressure CO absorption in special solution KS-12

c) CO regeneration 2

d) CO compression to desired level2

Advantages

Though regeneration energy is very high in comparison to that of any normal CO 2

removal section of ammonia plant, the cost effectiveness of the plant is very attractive because of the use of costlier Naphtha (as feed to balance the CO for Urea 2

production) shall be stopped completely. There is substantial reduction in CO 2

Emission as well.

10.5.7 Parallel S-50 Converter

Technology Description

The S-50 converter is a single bed radial flow converter, which is added downstream of the main converter to increase the ammonia conversion and at the same time improve the steam generation.

Advantages

The converter allows ammonia synthesis loop to operate at lower pressure with increased conversion per pass.

10.5.8 Conversion of Single Stage GV System to 2-Stage GV System for CO 2

Technology Description

Ammonia is manufactured by steam reforming of natural gas. During the process, CO is formed in the gaseous mixture and the same is removed from the gaseous 2

mixture in the CO Removal Section designed by M/s. Giammarco Vetrocoke (GV) 2

of Italy. The process gas containing CO enters the CO absorber where major 2 2

amount of CO is absorbed in the lower portion of Absorber in semi-lean GV 2

solution. Rest of the CO is absorbed in top portion of Absorber in lean GV solution. 2

The process gas, with around 300 ppm of CO , leaves the Absorber from top. 2

The main feature of original single stage GV system are (1) Absorption by only lean GV solution and (2) Stripping only in one Regenerator. The heat of regeneration is provided by vapours generated in GV Reboilers heated by Process gas and live LP steam. Full quantity of GV solution is sent to flash tank after GV Reboilers to remove maximum amount of vapour and CO . This lean GV solution goes to GV 2

Absorber in two parts, the hot solution to the middle to absorb major amount of CO 2

and cold GV solution to the top of GV Absorber to absorb the residual CO .2

The main features of the modified 2-stage GV process are (1) Absorption by lean & semi lean solutions in GV absorber (2) High pressure & low-pressure stripping in HP Regenerator and LP Regenerator. The heat of Regeneration is provided by vapours generated in GV Reboilers heated by Process gas, steam generated in LP Steam Boiler heated by process gas and live LP steam. Partially regenerated GV solution (Semilean Solution) from Regenerators goes to GV Absorber to the middle to absorb major amount of CO and strongly regenerated cold GV solution (Lean 2

Solution) to the top of GV Absorber to absorb the residual CO .2

Advantages

The features result in better absorption of CO in Absorber and lower energy 2

consumption for regeneration of the solution in Regenerators. Major benefits of the modification are:

• Reduction of CO slip through Absorber by around 600 ppm, which has resulted 2

in:

• Higher availability of CO for urea production. 2

• Decrease in hydrogen consumption in Methanation Section.

• Decrease in LP steam consumption in CO Removal System from 38 T/hr to 2

15 T/hr.

• By this, an energy saving of around 1GJ/Tonne of ammonia can be achieved.

10.5.9 LTS Guard Reactor & BFW Preheater

Technology Description

The reformed gas from Reforming Section flows to HT Shift Convertor after o ocooling in HP Waste Heat Boiler from 988 C to 380 C. The carbon monoxide

content of the process gas is reduced from 12.96% to 3.46% in HT Shift Converter through shift reaction, which takes place in the reactor in presence of Iron-chromia

ocatalyst. Process gas temperature of around 444 C at the outlet of HT Shift oConvector is reduced to around 210 C by heat recovery in a Waste Heat Boiler and

Boiler Feed Water Preheater.

Installation of a new LT Shift Guard Reactor before LT Shift Converter reduces the CO slippage from the Shift Conversion Section. The CO slip gets considerably lowered with the LT Shift Guard in line. Lower CO slip in turn, results in additional Ammonia production due to reduction in the consumption of hydrogen in Methanator. Considerable energy saving can be achieved by installation of a BFW Preheater down stream of the new LT Shift Guard Reactor.

Advantages

Reduction of CO slip through Shift Conversion Section by around 300 ppm. This gives higher availability of CO for urea production. Hydrogen consumption in 2

Methanation Section can also be considerably decreased. Installation of the BFW Preheater results in considerable energy savings.

10.5.10 The Poolcondenser concept (Urea Production)

Technology Description

The Poolcondenser concept is introduced to de-bottleneck very large capacities indeed. In case a stripping plant is considered in urea plants, the Poolcondenser is installed with a parallel-operated stripper. Conventional urea plants are revamped by using this concept to change the plant into a stripping unit. In this way the plant capacity is increased and the utility consumption is decreased drastically. The Poolcondenser is a horizontal high-pressure vessel in which reaction volume and condensing including retention time, which is needed to produce urea, is already in this Poolcondenser. The technology is implemented at PIC in Kuwait.

Advantages

Very large capacities are de-bottlenecked.

10.5.11 Modified trays in Urea reactor

Technology Description

Due to advancement in technology and current fertiliser scenario, it is necessary to

333332

335334

upgrade the plant equipments to reduce energy consumption. One new development is new modified tray design for Reactor in place of conventional design. Installation of these modified trays have further improved plug flow and reduced back mixing in the reactor and hence conversion of Ammonium Carbamate to Urea in the Reactor is enhanced.

Advantages

Conversion efficiency in Reactor is increased with considerable saving of medium pressure steam per tonne of production. Materials of construction of new trays are more corrosion resistant and have more life as compared to material used for conventional trays.

10.5.12 Use of Advanced Process Control (APC) with Distributed Control System (DCS)

In control theory, Advanced process control (APC) is a broad term composed of different kinds of process control tools, often used for solving multivariable control problems or discrete control problem. APC are often used for solving multivariable control problems or discrete control problem. APC makes it possible to control multivariable control problems. Since these controllers contain the dynamic relationships between variables, it can predict in the future how variables will behave. Based on these predictions, actions can be taken now to maintain variables within their limits. APC is used when the models can be estimated and do not vary too much. Normally an APC system is connected to a distributed control system (DCS). The APC application will calculate moves that are send to regulatory controllers. Historically, the interfaces between DCS and APC systems were dedicated software interfaces. Nowadays the communication protocol between these system is managed via the industry standard Object Linking and Embedding (OLE) for process control (OPC) protocol.

Advantages

The key advantages of APC with DCS are:

• Safer plant operations • Avoiding unnecessary plant trips • Better plant performance and maximized production

10.5.13 Simulation of Absorption and Desorption Columns for CO Removal2

Technology Description

A computer programme has been developed which simulates the performance of an absorption column for CO removal by using chemical solvents such as DEA 2

promoted carbonate solution. The computer predictions have been validated by using industrial column data from fertilizer industries. In addition, another computer program has also been developed to simulate the performance of steam desorption of bicarbonate solution for solvent regeneration in the CO removal 2

systems of fertilizer plants.

Advantages

The modeling equations are rigorous as they take into account point to point variation of all important transport and physical parameters, heat effects, gas and liquid temperature profiles, enhancement in gas absorption due to mass transfer with chemical reaction, etc.

10.6 Case Studies

Case Study 1: Installation of a Pipe Reactor in Complex Plant

Brief

Energy savings

Annual savings : Rs. 21.0 MillionInvestment amount : Rs. 80.00 MillionPayback period : 45 months

Case Study 2: Replacing Reformer Tubes with Tubes of HPNb Material Stabilised with Micro-Alloys

Brief

Energy savings

Annual savings : Rs. 15.0 MillionInvestment amount : Rs. 50.0 MillionPayback period : 40 months

Case Study 3: Modernisation of the Ammonia Converter Basket

Brief

Before Improvement After Improvement In a phosphatic fertiliser complex, producing Ammonium sulphate and Mono-ammonium phosphate, the phosphoric acid, sulphuric acid and ammonia are reacted in a tank reactor to produce a melt of 85 % solids.

The plant replaced the existing tank reactor with a pipe reactor. The implementation of this project resulted in operation of the reactor at higher concentration. The outlet of the reactor was directly inserted into the granulator. Hence the concentration of the melt was maintained at about 95 %, as against < 85 % earlier. The increase in concentration of the melt reduced the drying requirement in the dryer. The furnace oil consumption came down from 20 liters/ton of product to 5 liters/ton of product.

Before Improvement After Improvement

Before Improvement After Improvement In a 357 TPD Ammonia plant involved in production of Urea and other Phosphatic fertilisers, the reformer tubes were made of conventional material with 25 % Chromium & 20 % Nickel.

The Reformer tubes were replaced with ‘modified HPNb materials stabilised with micro-alloys’ with higher Chromium & Nickel and stabilised with Niobium (25 % Chromium, 35 % Nickel, 1.5 % Niobium and traces of Zirconium). The replacement of the reformer tubes with modified superior material resulted in the following benefits:

• Reduction in thickness of tube from 20 mm to 10 mm • Increase in internal diameter of tubes from 100 mm to 120 mm

–it aided in packing additional catalyst to the extent of 35 % • Increase in capacity of the plant by 15 % • Reduction in Reformer tube skin temperature

The above benefits together resulted in reducing the energy consumption for production of Ammonia by 0.63 GJ / Tonne of Ammonia.

Before Improvement After Improvement

Before Improvement After Improvement In a 357 TPD Ammonia plant, the Ammonia converter basket had a conventional axial type basket. This needed an operating synthesis loop pressure of 300 bar. The catalyst used was Topsoe supplied of 10 mm size with a pressure drop of 5 bars. The conversion per pass was around 16 %. In 1992, the bottom exchanger developed a leak, leading to further reduction of ammonia conversion and increased loop pressure. The total production loss was around 30 %.

The converter basket was modified to an axial-radial type system. The replacement of the old axial type converter basket with the modern axial-radial system resulted in the following benefits: • Loop pressure reduced to 250 bar – reducing compression energy • Lower pressure drop in converter beds – 3 bar as against 5 bar before • Higher Ammonia production (a b ou t 10 TPD) The above benefits resulted in the reduction of energy consumption by 1.47 GJ / Tonne of Ammonia

Before Improvement After Improvement

337336

Energy savings

Annual savings : Rs. 20.0 MillionInvestment amount : Rs. 50.00 MillionPayback period : 30 months

Case Study 4: Installation of Waste Heat Boiler (WHB) at the Inlet of LTS Converter in Ammonia Plant

Brief

Energy savings

Annual savings : Rs. 8.20 MillionInvestment amount : Rs. 4.50 MillionPayback period : 7 months

Case Study 5: Installation of Make-up Gas Chiller at Suction of Synthesis Gas Compressor at Ammonia Plant

Brief

The compressor is the heart of nitrogenous fertiliser plant and is used for various purposes such as compressing the synthesis gas, air, re-cycle gas and ammonia. The compressor capacity is also one of the important parameters controlling the capacity of the plant.

Hence, the design of the compressor and its effective utilisation is essential for achieving higher production and lower energy consumption.

Energy savings

The implementation of this project resulted in the following benefits

Before Improvement After Improvement In an Ammonia plant, the Low Temperature Shift Converter (LTSC) was designed to operate at a inlet temperature of 238°C.

A Waste Heat Recovery Boiler (WHRB) was installed to reduce the temperature of the gases entering the LTSC to about 210°C. The installation of the WHRB resulted in the following benefits:

• Reduction of LTSC inlet temperature to about 210°C

and generation of 2 TPH of steam at 14 kg/cm2 • Prolonged life of LTSC catalyst • Increased process efficiency – Resulting in higher

Ammonia production by 0.9 % (a b o u t 3 TPD) The above benefits resulted in the reduction of energy consumption by 0.34 GJ / Tonne of Ammonia.

Before Improvement After Improvement

Before Improvement After Improvement A ammonia fertiliser complex producing 900 tons per day of Urea was operating at about 920 TPD of ammonia production. The synthesis gas was entering the compressor at about 39°C.

The plant installed a vapour absorption refrigeration system with LP steam for cooling the synthesis gas. The implementation of this project resulted in a saving of 117355 GJ per year, which amounted to 0.38 GJ / Tonne of ammonia

Before Improvement AfterImprovement

Parameter

Ammonia Production

Syn. gas temperature

Syn. gas compressor speed

Units

TPD

°C

RPM

BeforeImplementation

920

39

13,142

AfterImplementation

944 13

13,071

Annual savings : Rs. 9.80 MillionInvestment amount : Rs. 22.00 MillionPayback period : 27 months

Case Study 6: Replacement of Air Inter-coolers in the Ammonia Plant

Brief

Energy savings

Annual savings : Rs. 0.85 MillionInvestment amount : Rs. 2.00 MillionPayback period : 28 months

Case Study 7: Routing of Ammonia Vapours from Urea Plant to Complex Plant

Brief

Energy savings

Annual savings : Rs. 4.00 MillionInvestment amount : Rs. 0.50 MillionPayback period : 2 months

Case Study 8: Replacement of Pellet Type Catalyst with Ring Shaped Catalyst in Sulphuric Acid Plant

Before Improvement After Improvement In a 1,00,000 ton per annum capacity Ammonia plant, the air requirements of the Ammonia converter were being met by two numbers of oil lubricated 4 stage reciprocating compressors. The compressors were provided with inter-coolers with finned tubes and were laid in a horizontal fashion. The oil in the air from cylinders used to plug the gap between the fins and reduce the heat transfer. The exit air from the inter-cooler used to be at 55 – 58°C as against the design of 42°C. The capacity of the subsequent stages was getting reduced leading to loss of Ammonia production.

The inter-coolers for the compressor was replaced with finless tubes and laid in a vertical fashion. The replacement of horizontal fin type cooler with vertical finless coolers resulted in reduction of exit air temperature to around 45°C. There was a reduction of power to the extent of 45 kW.

Before Improvement After Improvement

Before Improvement After Improvement In a Urea & Phophatic fertiliser complex, ammonia is compressed from vapour to liquid

form by compression to 19 kg/cm2 in two reciprocating compressors and then condensed while in the other part of the plant, the liquid Ammonia (about 6 TPH) at 0°C was drawn from the storage spheres and vapourised at 6

kg/cm2 . Both these operation demand energy in the form of electricity for compression and steam for vapourisation.

The system was modified as below: § Ammonia was compressed to only 6 kg/cm2 in

the Urea plant. § The hot vapours were exported from the Urea

to the complex plant. The implementation of this project resulted in the following benefits: • Reduction of electrical energy consumption for compression of Ammonia in the Urea plant. • LP steam saving in the Complex plant The above benefits resulted in the reduction of energy consumption by 6 lakh units per year and 2000 T of LSHS.

Before Improvement After Improvement

339338

Before Improvement After Improvement In a sulphuric acid plant, which was a part of the larger fertiliser complex plant, pellet shaped V2O5 catalyst was being used. The plant was

frequently facing problems of dust accumulation and increase in pressure drop. Additionally the plant had to be shut down once every six months for screening and re-charging the catalyst.

The pellet shaped catalyst was replaced with ring shaped catalyst of the same material composition. The replacement of the pellet type catalyst with ring type catalyst resulted in the following benefits: • Reduction in the pressure drop build up of the converter • Reduction in the load of the main air blower • Shut down (for screening and recharging catalyst)

frequency reduced from two per year to once per year The above benefits resulted in the reduction of energy consumption by 900 tonne of LSHS and additional production of 10,000 tonne of sulphuric acid per year

Before Improvement After Improvement

Brief

Energy savings

Annual savings : Rs. 7.80 MillionInvestment amount : Rs. 40.0 MillionPayback period : 62 months

Case Study 9: Installation of High Efficiency Turbine for Air Blower in Sulphuric Acid Plant

Brief

Energy savings

Annual savings : Rs.9.60 MillionInvestment amount : Rs.15.0 MillionPayback period : 19 months

Case Study 10: Installation of Variable Frequency Drive (VFD) for Sulphur Pump

Brief

Energy savings

Annual savings : Rs. 0.75 MillionInvestment amount : Rs. 0.50 MillionPayback period : 8 months

Before Improvement After Improvement In the sulphuric acid plant (1200 TPD capacity) of a huge fertilizer complex, the sulphur furnace blower was driven by a single stage turbine operating

between 35 kg/cm2 and 3.5 kg/ cm2. The turbine had a specific steam consumption of 16.9 tons per MW. The turbine was consuming about 27 TPH of steam during normal operation. There was also a mis-match of LP steam generation and requirement, resulting in an average venting of

LP steam (pressure of 3.5 kg/cm2) of about 4 TPH.

The single stage turbine was replaced with a new multi-stage steam turbine of higher efficiency. The improvement in efficiency was about 15 % resulting in reduction of steam consumption by about 3 TPH, even when operating at higher load. The implementation of this project resulted in the

saving of about 3 TPH of steam (35 kg/cm2).

Before Improvement After Improvement

Before Improvement After Improvement In the sulphuric acid plant (1200 TPD capacity) of a huge fertiliser complex, the sulphur pump was being driven by a steam turbine with inlet

steam at 35 kg/cm2. The pump was of 10.2 m3/h capacity and 265 m head and was being controlled by re- circulation. Also, the turbine driving the pump was a small one consuming a maximum of about 0.7 TPH of steam. Since the quantity of steam was less, the exhaust was let out into the atmosphere.

The steam turbine was replaced with a motor of 22 kW with a variable frequency drive. There were two pumps and one was operated continuously. The replacement was done for one of the pumps and other turbine driven pump was kept as a stand-by. The implementation of this project resulted in the saving of about 0.4 TPH of steam. The motor installed along with VSD was consuming about 15 kW

Case Study 11: Optimisation of Vacuum Pump Operation

Brief

Energy savings

Annual savings : Rs. 0.37 MillionInvestment amount : MinimalPayback period : Immediate

Case Study 12: Coating of Pump Impeller and Casing with Composite Resins

Brief

Energy savings

Annual savings : Rs. 0.7 MillionInvestment amount : Rs. 0.5 MillionPayback period : 9 months

Case Study 13: Installation of Hydraulic Turbine in the CO2 Removal Section

Brief

3

Before Improvement After Improvement In a phosphatic fertiliser unit, which is part of a bigger fertiliser complex involved in production of complex fertilisers, a long belt filter was being used for final filtration of the slurry of silica and AlF3. Two vacuum pumps of 500 m3/h capacity and 0.3 kg/cm2 vacuum were being used for creating vacuum. One of the vacuum pumps was being operated with valve throttling.

The detailed study of the system revealed the following: · There were leaks in the vacuum line joints

close to the belt filter. · The capacity of the vacuum pump was

reduced due to uneven wearing of the pump

During a maintenance stoppage of the plant, the leakages were arrested and a trial was taken to operate the filter with one vacuum pump. The trial was satisfactory and the operation of one vacuum pump per filter was made into a standard operating procedure. The power saving was about 15 kW, which annually amounted to 1,20,000 units

Before Improvement After Improvement

(8000 hrs/year operation)

Before Improvement After Improvement In a sulphuric acid plant of 600 TPD capacity,

there were 4 cooling water pumps of 2700 m3

/h capacity and 50 m head driven by a 500 kW motor. The pumps were operating at an efficiency of 64.5 %, consuming about 430 kW.

The casing of the pump was coated with epoxy resin coating. Consequent to the coating the efficiency of the pump had improved and there was a reduction of about 16 kW in the power consumed by each pump. The total saving was about 0.13 million units.

Before Improvement After Improvement

In a sulphuric acid plant of 600 TPD capacity, 3there were 4 cooling water pumps of 2700 m /h

capacity and 50 m head driven by a 500 kW motor. The pumps were operating at an efficiency of 64.5%, consuming about 430 kW.

Before Improvement After Improvement In a particular nitrogenous fertiliser plant of about 1,00,000 tons per year capacity, the aqueous mono ethanol amine (MEA) process was being used for CO2 removal. This MEA absorbed in the CO2 absorber which is at a pressure of 24 kg/cm, enters the CO2 stripper operating at a lower

pressure of around 0.4 kg/cm2. This pressure reduction is effected through a pressure- reducing valve.

A Hydraulic Power Recovery Turbine (HPRT) was installed to recover the pressure energy being lost across the valve. The implementation of this project resulted in reduction of the load on the steam turbine driving the lean MEA pump. The steam saving on the steam turbine amounted to 2.5 TPH of high-pressure steam, which annually amounted to about 600 tons of LSHS. The reduction in specific energy consumption amounted to about 0.06 Gcal / Tonne of ammonia.

Before Improvement After Improvement

2,

341340

Energy savings

Annual savings : Rs. 3.80 MillionInvestment amount : Rs. 1.10 MillionPayback period : 4 months

Case Study 14: Replacement of steam ejectors with vacuum pumps

Brief

Energy savings

Annual savings : Rs. 10.00 MillionInvestment amount : Rs. 7.50 MillionPayback period : 9 months

Case Study 15: Re-processing of Purge Gas for Ammonia-fertiliser

Brief

Case Study 16: Reprocessing of CO waste gas for ammonia/ methanol

Brief

A stream of gas generated in gasification unit, containing mainly CO + H is used 2

for 50,000 TPA acetic acid plant. This gas stream is purified to remove impurities of CO and H S, followed by CO enrichment. This 99.5 percent pure CO is used for 2 2

production of acetic acid. In the process of CO enrichment, a waste CO + H stream 2

is generated. The hydrogen of this stream is reprocessed in nitrogen wash unit for enhancing ammonia production as in-built feature. However, CO content of the stream is lost in tail gas stream of nitrogen wash unit.

Energy savings

A scheme to use this stream in methanol plant is made which will spare hydrogen for increasing ammonia production by 7 TPD.

Before Improvement After Improvement In one of the complex fertilizer-manufacturing units, there were five evaporators for concentration of phosphoric acid. The evaporators were operated under vacuum using 2-stage steam ejectors. These ejectors consume about 1.5 TPH each of 27-kg/cm2 pressure steam.

All the five steam ejectors in evaporator section were replaced with water ring vacuum pumps. The steam saved by replacement was equivalent to about 7.5 TPH of 27- k g / cm2 pressures. This can generate additional power equivalent to about 50 units/ ton of steam, thereby offsetting equivalent power drawn from the grid

Before Improvement After Improvement

Before Improvement After Improvement The 10,000 TPA methanol plant based on natural gas reforming is designed with a purge of 5, 000 Nm3/ hr from methanol synthesis section, which is used as a part of fuel in reformer. The purge stream is having 70 percent of hydrogen, which is having low heating value.

Productive use of this stream containing about 3,500 Nm3/ hr available hydrogen was thought of to produce ammonia. The compatibility of the stream was established in ammonia plant upstream of rectisol wash unit after boosting the pressure from 54 to 75 bars by using a recycle compressor. After implementing the scheme, ammonia production could be increased to the tune of 40 T/ day on consistent basis. Also part of purge gas is reprocessed to pure hydrogen after installing pressure swing absorption unit. The hydrogen is supplied for producing aniline (20,000 TPA) 54 BAR

Before Improvement After Improvement

at 54 BAR

Case Study 17: Re-use of Condensate Streams from Different Locations

Brief

In the CO-shift reaction 50 T/hr of water is consumed from the saturated gas generated by gasification. Grey water circuit of carbon extraction unit supplies this water. Also about 20 Tonne/ hr of water is required to blow-down from the grey water drum to maintain chloride and TDS in the system. This 70 Tonne/ hr of water requirement is met by make-up of BFW or condensate to grey water drum as per design. This being very high consumption of BFW the use of waste streams available was thought of and the following streams were identified and connected with grey water circuit.

1. Urea plant hydrolyser effluent : 30 Tonne/ hr is recycled to grey water drumthrough a control valve. The contaminants limits are fixed at 100-ppmammonia and 50 ppm urea.

2. Formic acid plant : 10 Tonne/ hr condensate of stream is taken to grey waterdrum by pump.

3. Methanol plant : 20 Tonne/ hr condensate containing about 5 ppm methanol isdiverted to grey water drum.

Energy savings

Load on DM water and BFW system is reduced by about 60 Tonne/ hr giving considerable savings.

Case Study 18: Installation of modified trays in Urea reactor

Brief

A major plant had modified the old Reactor trays of 11 & 21 units of Urea Plant-I with new design trays .M/S Snamprogetti, Italy (technology supplier for Urea Plant) have developed a new modified tray design for Reactor. In place of 10 Nos. of identical sieve trays of conventional design (each having 363 nos. holes of 8 mm each on square pitch), 15 Nos. trays of modified Snamprogetti design have been installed. Each set of 5 new trays has 1922, 1281 & 941 holes of 8 mm dia. each on triangular pitch. Installation of these modified trays have further improved plug flow and reduced back mixing in the reactor and so conversion of Ammonium Carbamate to Urea in the Reactor is enhanced.

Energy savings

Saving of around 30 kg of medium pressure steam (24 ata) per tonne of fertliser produced has been achieved due to increased reactor efficiency. Material of construction of new trays is 2-RE-69, which is more corrosion resistant and shall have more life as compared to SS 316 LM material used for conventional trays.

Energy Saving Achieved: 0.0063 GJ/Tonne of urea.

Case Study 19: Conversion from Naphtha to R-LNG as feedstock

Brief

A major plant initiated the task of executing RLNG conversion along with Energy Saving Project. As the availability of indigenous natural gas was limited, the only possible alternative was to go for RLNG which was to be sourced from outside andmade available to the unit as per the requirement. The unit held discussions with

343342

the concerned parties and finally an agreement was reached between the gas supplier and the unit for gas supply. A separate 140 KM pipeline was laid from Thulendi of District Rai Barelly to the Unit from the existing HBJ gas pipeline.

Energy savings

• Easy and shorter start up of the plant, thereby lesser unproductive consumption• No burners choking problem • Reduced CO emission from furnace 2

• Trouble free running of plant • Increased life of catalyst

Case Study 20: Installation of Carbon Dioxide Recovery (CDR) Plant

Brief

A major unit has installed a Carbon Dioxide Recovery (CDR) Plant, to recover CO 2

from flue gases of Ammonia plant primary reformer furnace. The capacity of the plant is 450 TPD of CO and M/s MHI, Japan has provided the basic engineering 2

for it. M/s TICB was engaged as turnkey contractor for detail engineering, procurement, erection and commissioning. CDR plant is basically a low pressure CO removal section in which CO present in flue gases is absorbed & then 2 2

regenerated to produce CO having 99.93 % purity. 2

Energy savings

• Cost effectiveness of the plant is very attractive because the use of costlier Naphtha as feed to balance the CO for Urea production shall be stopped2

completely. This offsets higher conversion costs.• Reduced CO Emission2

References

1. Annual Report 2007-08, Ministry of Chemicals & Fertilizer, Department ofFertilizers, GoI.

2. Technology Assessment Report - Fertiliser Sector: Fertiliser Association of India

3. "Energy Efficiency Gains in Indian Ammonia Plants Retrospect andProspects", Sachchida Nand, Manish Goswami; 2006 IFA TechnicalSymposium, 25-28 April 2006, Vilnuus, Lithuania.

4. LBNL - 57293; Assessment of Energy use and energy savings potential inselected industrial sector in India, August 2005.

5. Indian Journal of Fertilizers, Vol - 4, No.9, September 2008 (ISSN 0973-1822)6. Compendium of Workshop - "Adoption of Energy Efficient process

technologies & practices and implementation of Energy Conservation Act2001 in Fertilizer Sector" by BEE at New Delhi on 1st September, 2008.

7. TERI Energy Directory and Yearbook 20078. LBNL-41846: India's Fertilizer Industry: Productivity and Energy Efficiency;

Katja Schumacher and Jayant Sathaye; Earnest Orlando Lawrence BerkleyNational Laboratory, Environmental Energy Technologies Division, July1999

9. Statistical Abstract 2007 - CSO10. CII - IREDA Publication: "Investors Manual on Energy Efficiency".11. Japan Energy Conservation Directory

12. LBNL - 62806; World Best Practice Energy Intensity Value for SelectedIndustrial Sectors, February 2008

13. LBNL - 54828: Emerging Energy Efficient Technologies in Industry casestudies of selected technologies - May 2004

14. National Energy Map of India: Technology Vision 203015. Report of the working group on Power for 11th Plan (2007-12)16. Report of the working group on R&D for the Energy Sector for the formulation

of the 11th Five Year Plan (2007-12)17. BP Statistical Review, June 200818. http://fert.nic.in19. www.energymanagertraining.com20. www.faidelhi.org21. www.eeii.org.in

345

Notes

11.1 Introduction

The Indian pulp and paper industry is over a hundred years old. First mill in the country was commissioned in 1812 in Serampur (W. Bengal). Over the years, the installed capacity has grown from a paltry 0.15 million tonnes in the early fifties to the present level of 8.3 million tonnes.

However, the growth of the industry has been uneven and as a result, the Indian paper industry is a mix of large integrated plants based on wood based raw material and medium and small size paper plants based on waste paper. The capacities of the mills range from 500 tonnes/annum to 2.0 lakh tonnes/ annum.

There are about 700 units, which manufacture pulp, paper, paperboard and newsprint paper, out of which nearly 570 are in operation. The total installed capacity is nearly 83 lakh tonnes out of which 11 lakh tonnes are lying idle due to closure of many units.

Based on the raw material utilized, the paper units can be classified into three broad categories as:

• Wood based (Bamboo, hardwood etc.)• Agro-based (Bagasse, jute, rice & wheat straw)• Waste paper based

The Indian scenario on production of paper and paperboard, import and export during the last 4 years is given below in Table 11.1

Table 11.1 : Installed Capacity, Production, Import & Export of Paper

(Source: CPPRI & CMIE)

11.2 Manufacturing Process

A variety of processes are in use in the paper industry depending on the type of raw material used and the end product desired. Among these, Kraft (Sulphate) process, Semi-Mechanical process and Sulphite process are the most popular ones. In the Indian pulp and paper industry, the Kraft process dominates the wood/bamboo pulping. Paper making essentially consists of following stages:

• Preparation of pulp • Stock preparation• Sheet formation & water removal

(In Lakh Tonnes)

Chapter - 11

Pulp & Paper

Year Installed

Capacity

Production Imports Exports

2004-05 74.0 58.90 1.95 2.70

2005-06 76.0 59.00 2.85 2.92

2006-07 78.0 61.40 3.47 3.39

2007-08 78.0 41.58

(Upto November, 2007)

0.64

(upto May,

2007)

N.A.

347346

11.2.1 Preparation of pulp

11.2.1.1 Wood preparation

Hard wood logs are debarked by wet or dry process depending upon the size of the logs handled. Small diametric logs are debarked by dry process by friction. In wet process, debarking of larger logs of wood is done by drum or pocket barkers.

Hydraulic barking uses high-pressure water jets to separate bark and log. Energy requirement for friction barking is lower than that for hydraulic barking. In India, most of the mills are not doing debarking as they receive either debarked wood or use them with bark due to difficulty in debarking of some hardwoods. The logs are chipped to size suitable for pulping using chippers. Dise and drum chippers are used for chipping. The oversized chips are rechipped, as under sized chips are rejected.

11.2.1.2 Pulp making

Predominantly, pulp making is done either by mechanical or chemical means. In mechanical process, the wood is reduced to small particles by rubbing against huge grindstones revolving at high speeds. Groundwood mechanical process is the most commonly used and most of the Newsprint paper production is undertaken through groundwood pulp process. In India, chemi - mechanical pulping (CMP) is done by only one newsprint paper mill. In CMP, the wood chips are subjected to a mild chemical treatment prior to mechanical separation using a refiner. In the chemical process, the cellulose fibers of the wood are separated from the non-cellulose components by chemical action.

Three primary chemical processes are in use, viz., Kraft or sulphate (alkaline), Sulphite (acidic) and Neutral Sulphite Semi Chemical (NSSC). As mentioned earlier, all large Pulp & Paper mills in India use the Kraft sulphate chemical process for pulping. In this process, the raw material (almost any kind of wood - soft or hard) is cut and chipped to produce chips of 0.5-1" size. These chips are fed into digesters, reacted with white liquor (80:20 NaOH and Na S) and steamed for about two to 2

o 2three hours at high temperature and pressure (162 - 168 C and 7-8 kg / cm ). Digesters may be batch or continuous type, the latter offering advantages such as increased throughput, reduced labour and better energy utilization. Continuous digesters are also very useful in agro fiber pulping. Many mills using agro residue use Pandia Continuous Digesters. The pulp is then washed to make the pulp free from soluble impurities and removal of black liquor through usual 3 or 4 stages of counter current washing using rotary drum filters. The washed pulp is sent for bleaching to increase the brightness of the pulp and the dilute black liquor is sent to evaporators. The treated pulp then goes for stock preparation. The black liquor after concentration is fired in recovery boilers. The residue "green liquor" is treated with lime to get white liquor for reuse.

In Soda process, which is mostly used for pulping of agricultural residues, Sodium Hydroxide (NaOH) is the main cooking chemical. Other cooking parameters are almost same as Kraft process.

11.2.1.3 Bleaching Process

Pulp when it comes from digester, contains residual coloring matter. This unbleached pulp may be used for making heavy wrapping paper or bags. However, paper to be used for printing, writing or paper which is to be dyed, must first be bleached. The main object in bleaching is to remove residual lignin from the wood pulp fibers as well as to destroy or remove remaining colouring matter. Now a days, various bleaching agents are used to bleach the pulp like chlorine, chlorine dioxide, hydrogen peroxide, oxygen & calcium hypo chlorite

11.2.2 Stock preparation

Stock preparation is undertaken to give the pulp various desired qualities through refining. It is mostly accomplished in either double disk or conical refiners. A more vigorous and special type of refiner, known as Jordan, is used in mechanical pulp preparation method, in which a conical plug rotates in conical shell. The stock then undergoes addition of sizing, filling, and coloring agents. A final screening & centricleaning is carried out prior to paper making for removing the contaminants as they may lead to defects in paper.

11.2.3 Sheet formation & water removal

The feed to the paper machine consists of combination of refined pulp together with additives, such as fillers and wet end chemicals, having requisite stock consistency. Either Fourdrinier or cylindrical mould machines form the above feed into a sheet. Mills producing cultural and newsprint paper use high-speed fourdrinier and twin wire sheet formers. Mills producing packaging paper & board mainly use cylindrical mould machines. At wet end of paper machine, water is first removed by gravity, then by suction, then by pressing the sheet and lastly by drying by steam heated cylinders.

11.3 Per Capita Consumption

The per capita consumption of paper in the different parts of the world are depicted below:

Figure - 11.1

Per Capita Consumption (kg/year)

Source : CII - IREDA & CPPRI

The Indian per capita consumption of paper is 7 kg, in comparison to the Asian average of 21 kg, World average of 55 kg and US average of 331.7 kg. So the Indian pulp and paper industry has got a tremendous growth potential estimated at about 8% per year.

350

300

250

200

150

100

50

0 India Indonesia China Thailand Brazil Japan USA UK

349348

11.4 Energy Profile

The share of energy costs in the total manufacturing cost is close to 25%. Coal and electricity are the two major energy sources used in the paper production. Other fuels, such as low sulphur heavy stock (LSHS), furnace oil, etc. are also used to fire boilers. Light diesel oil (LDO) and high-speed diesel (HSD) are also used for captive power generation in diesel generator sets in plants. The Steam and Electricity generated by energy facilities as shown in figure 11.2 are used by various production facilities. Steam and electricity consumption per tonne of paper is 11-15 tonnes and 1500-1700 kWh respectively in Indian mills. The total specific energy consumption of Indian pulp and paper industry ranges from 31 to 52 GJ (Giga joules) per tonne of product, which is roughly double the norms compared to North American and Scandinavian units. The overall energy conservation and utilization efficiency in Indian Pulp & paper mills is very low compared to mills in developed countries.

It shows that there is immense potential of energy savings in this sector.

Figure - 11.2: Conversion & Utilisation of Energy in Paper Industry

Source: CPPRI

The energy consumption pattern varies according to type of raw material and the technology used by a particular mill.

11.5 Energy Intensity

The paper industry is highly energy intensive and is the sixth largest consumer of commercial energy in the country.

Large paper plants generate part of their own power through cogeneration, while smaller plants depend exclusively on purchased power.

The energy cost, as a percentage of manufacturing cost, which was about 15% a few decades earlier is presently about 25%. This is mainly due to the increase in energy prices.

The expenditure on energy ranks only next to the raw material in the manufacture of paper. With the ever-increasing fuel prices and power tariffs, energy conservation is strongly pursued as one of the attractive options for improving the profitability in the Indian pulp and paper industry.

Boiler

Evaporator

Paper Machine

Chemical Recovery

Bleaching

Digestor

Stock Preparation

Screening/centricleaning

Washing

Raw material Preparation

Section

Indian

Mills

International

MillsDigester 2.50-3.90 1.9-2.3 Bleach Plant 0.35-0.40 0.20-0.25 Evaporator 2.50-4.00 1.50-2.30 Paper Machine 3.00-4.00 0.70-2.00 Soda Recovery Plant 0.50-1.10 0.30-0.50 Total 11.0 - 14.0 6.5 - 8.5

Section

Indian

Mills

International

MillsDigester 58-62 43-46 Bleach Plant 88-92 66-69 Paper Machine 465-475 410-415 Soda Recovery Plant 170-190 127-135 Stock Preparation 275-286 164-172 Utilities & Others 246-252 160-165 Chippers 112-128 92-98 Washing

& Screening

145-155

116-123

Total 1500-1700 1150-1250

Parameter

Steam

Power

Water

Total energy

Units

MT/ MT of FNP

KWh/ MT of FNP

3m / MT of FNP

GCal/ MT of FNP

Indian Mills

11-147.5

1500-17001200-1300

15075

5231

International Mills

6.5-8.56.0

1150-1250900-1000

5025

2818

Norm

Avg.Best

Avg.Best

Avg.Best

Avg.Best

The specific energy consumption comparison of Indian paper industry vis-à-vis the international trends is as follows (Table -11.2):

Table 11.2: Comparison of Specific Energy Consumption

Source: CII-IREDA & CPPRI

The typical break-up of steam and power of the various Indian mills vis-à-vis the international mills is shown in Table 11.3 (a) & (b):

Table 11.3 (a) : Consumption of Section wise Steam consumption

(MT/MT of FNP)

Source: CII-IREDA & CPPRI

Table 11.3 (b) Comparison of Section wise Power Consumption (kWh/MT of FNP)

Source: CII-IREDA & CPPRI

11.6 Energy Saving Potential

The various energy conservation studies conducted by PCRA and feedback received from the various industries through questionnaire survey and plant visits indicate an energy savings potential of 20%.

This is equivalent to an annual savings potential of about Rs.3000 million. The estimated investment required to realize this savings potential is Rs.5000 million.

The pulp and paper industry has an attractive cogeneration potential of over 100 MW, in addition to the existing cogeneration plants.

351350

11.6.1 Major factors affecting energy consumption in paper mills

The major factors that affect energy consumption in the Indian pulp and paper

industry are:

• Low level of capacity utilisation• Quality and type of paper produced• Number and multiplicity of machinery• Paper machine renewability and down time • Finishing losses• Boiler type & pressure levels• Level of cogeneration • Power generation

Section-wise details of factors, which affect energy efficiency, are given below:

• Type of raw material preparation section- Type of chippers/ cutters- Type of conveying system

• Digesters system

- Type of pulping technology (RDH and extended dezincification

preferred using oxygen dezincification)- Installation of blow heat recovery- Optimal bath liquor ratio

• Washing section

- Utilisation of advanced washers, such as, flat belt wire washers, double

wire press, DD washer and Twin drum washer

• Screening section

- Installation of advanced screening equipment

• Stock Preparation

- Type of refiners- Type of centri-cleaners (use of low pressure drop centri- cleaners reduce

the pumping power consumption)

• Paper machine

- Type of press- Percentage moisture after press section- On-line moisture control- Type of hood system- Type of siphon for condensate removal

• Evaporation section

- Type of evaporator and number of stages- Steam economy achieved (minimum should be 6)- Extent of condensate recovery

• Other Factors

- Type of river water pumping system and overall water consumption- Levels of instrumentation- Extent of utilisation of variable speed drives, such as, variable frequency

drives (VFD), variable fluid couplings (VFC), DC drives, dyno -drives etc.

Apart from the above factors, optimized operation and proper maintenance are also very important for energy efficiency.

11.6.2 Target specific energy consumption figures

The overall specific energy consumption norms for large integrated paper plants, producing writing and printing paper, using 100% chemical bleached pulp and operating on sulphate process, should be as highlighted below:

• Steam = 9.00 MT/MT of finished paper• Power = 1300 kWh/MT of finished paper

3• Water = 100 m /MT of finished paper

The break-up of the target specific steam, specific power and specific water consumption figures in the different sections of the plant are given in table 11.4 (a), 11.4 (b) and 11.4 (c)

Table 11.4 (a): Specific Steam Consumption break-up (MT/MT of FNP)

Source: CII-IREDA & CPPRI

Table 11.4 (b): Specific Power Consumption break-up (kWh/ MT of FNP)

Source: CII-IREDA & CPPRI

Section Steam

Pulping & washing 1.2

Bleaching 0.4

Black Liquor Evaporation 2.4

Chemical recovery boiler

0.8

Recausticising

& Lime kiln

0.5

Paper machine

2.0

Deaerator 1.4

Section Power

Chippers 30Digester house 55Washing and Screening

105

Bleaching plant

105Stock preparation, Paper m/c and Finishing

500

Power boilers

170

Intake well + Water treatment plant

60

Recovery

(Evaporator, recovery boiler, causticisers and lime kiln)

175

Effluent treatment plant

60Lighting and workshop etc. 50Total 1300

353352

3Table 11.4 (c): Specific water consumption break-up (100 m /MT of FNP)

Source: CII-IREDA & CPPRI

11.7 Technologies for Energy Conservation

11.7.1 Recovery of Chemicals from Spent Liquor Obtained from CounterCurrent Washing of Unbleached Pulp

Technology Description

The chemical recovery systems (evaporators, recovery boilers etc.) are an integral part of any large integrated paper plant. The black liquor can be fired in the soda recovery boilers to generate steam. The sodium salts recovered in the process is reused in the digesters. The installation of such chemical recovery systems in the medium size paper plants is generally considered financially unattractive. Installation of Fluidized Bed Reactor to recover chemicals in medium size paper plant offers an attractive option. The reactor recovers chemicals from spent liquor and converts them into sodium carbonate pellets. These pellets are commercially sold, resulting in additional revenue generation.

Advantages

• Recovery of Chemicals (Sodium Carbonate) from spent liquor results insaving of power and savings of chemicals like Urea and DAP in the effluenttreatment plant.

Case Study 1: Recovery of Chemicals from Spent Liquor Obtained from Counter Current Washing of Unbleached Pulp in a Medium Size Paper Mill

Brief

Energy savings

Annual savings : Rs. 6.2 MillionInvestment Required : Rs. 12.6 MillionPayback period : 24 months

Section Water

Pulp Mill 30 Paper machine 20 Boilers incl. WTP and Cooling tower 30 Chemical recovery area 10 Miscellaneous

10

Total 100

Before Improvement After Improvement

In an agro-based medium size paper plant, the spent liquor obtained from the counter current washing of unbleached agro-pulp, was getting mixed with wastewater and let out to effluent treatment plant. This increases the load on the effluent treatment plant, as it is not possible to bring down the Sodium ratio in the effluent.

A chemical recovery plant, to recover the chemicals from spent black liquor, obtained from the counter current washing of the unbleached agro-pulp, was installed.The following benefits were achieved on the installation of chemical recovery system:

• Chemical recovery (SodiumCarbonate)

• Savings in power at the effluenttreatment plant

• Savings in Urea and DAP at theeffluent treatment plant

11.7.2 Waste heat recovery from waste sludge in pulp and paper industry

Technology Description

An efficient technology for processing of sludge including waste-to-energy aspect and energy recovery has been developed by University Department of Chemical Technology, Mumbai and Paper & Pulp Technology Department, Sant Gadgebaba Amaravati University, Amaravati. The retrofit has been realized in two stages. The waste sludge is burnt in a multiple hearth incinerator with a fluidized bed chamber. The different stages of retrofit, can be characterized as “waste-to-energy”, where heat from flue gas is utilized for generating the steam, drying the sludge, pre-heating air for combustion & fluidization and water preheating for steam generation. Off-gas cleaning system consists of a filter for particulate removal and a three-stage scrubber system is attached for cleaner stack.

Advantages

• The technology is favourable both economically and environmentally.

11.7.3 Seven Effect Free Flow Falling Film (FFFF) Evaporator

Technology Description

Multiple effect evaporators are installed in the liquor line between the brown stock washers and the soda recovery boiler to efficiently remove large amounts of water from the liquor, so that, the recovery boiler produces steam from this liquor economically. The multiple effect evaporator is fed black liquor at 12-14% solids concentration and concentrated to 40-55% solids. Most of the paper plants use the short tube or long tube vertical evaporators, having five to seven effects, the first two effects being contained in one evaporator body. The latest trend among the large integrated paper plants is the installation of free flow falling film evaporators. They are characterised by higher steam economy and better operational performance.

Advantages

• The installation of 7-effect FFFF evaporator resulted in achieving steam economy of 6 tons of water evaporation per ton of steam.

Case Study 2: Installation of Seven Effect Free Flow Falling Film (FFFF) Evaporator

Brief

A large integrated paper plant had a conventional quintuple effect short tube vertical evaporator system for the concentration of black liquor. The black

3liquor flow rate was about 2500 m /h.The steam economy achieved was 2.8 tons of water evaporation per ton of steam. These evaporators had frequent operational problems, leading to increase mechanical down time. Also the chemical losses were more due to the frequent water boiling.

Before ImprovementThe latest 7 - effect free flow falling film evaporator, was installed in place of the conventional short tube vertical evaporator. The installation of 7-effect FFFF evaporator resulted in achieving a steam economy of 6 tons of water evaporation per ton of steam. A net saving of about 9700 MT of low-pressure steam was achieved as a result of this modification.

After Improvement

355354

Energy savings

Annual savings @ Rs. 3.00 per kg of steam : Rs. 29.1 MillionInvestment required : Rs. 36.9 MillionInvestment required : 15 months

11.7.4 Use of Variable Frequency Drives (VFD's) in Washer Drum Drives

Technology Description

One step in paper manufacturing process is washing of pulp to remove free soluble impurities and black liquor, thereby recovering maximum amount of spent chemicals. The washing is done using rotary drum washers driven by variable speed systems to achieve desired speed variation, according to the throughput of the plant. The dyno-drives used for the purpose, though have lesser maintenance problems, are inefficient at lower speeds. The variable frequency drives (VFDs) are more efficient at lower/all speeds and require lesser maintenance, in comparison to the dyno-drive.

Advantages

• VFDs are more energy efficient at all speeds and enable precise control of speed.

Case Study 3: Replacement of Dyno-drives with Variable Frequency Drives (VFD's) in Washer Drum Drives

Brief

The contents of the digester, after cooking, are blown down to a blow tank. The blown pulp is then washed, to remove the dissolved lignin and chemicals. Usually, washing is practiced in counter current fashion, involving 3 or 4 stages of washing, using rotary drum washers. The washed pulp is then sent for bleaching and further processing. The rotary drum washers are operated under vacuum, utilizing a barometric column. These drum washers are driven by a variable speed system, to achieve the desired speed variation, according to the throughput of the plant.

Energy savings

Annual savings @ Rs. 4.5/kWh : Rs. 0.16 Million per year.Investment required : Rs 0.25 MillionPayback period : 19 months

11.7.4 Sonic Soot Blowers in Place of Steam Soot Blowers for Coal Fired Boilers

Technology Description

Coal fired boilers are installed to meet the steam requirements of the paper plant. The boiler water tubes get frequently coated with soot deposits, as a result of combustion of coal in coal-fired boilers. The cleaning of tubes has to be carried out

In one of the old integrated paper plant, the washer drum drives were fitted with dyno-drives. The washers were operating at 50 - 60% of the rated speed for majority of the time. The dyno-drives are very inefficient at lower speeds.

The dyno-drives of the washers were replaced with variable frequency drives (VFD's).The replacement of dyno-drives with VFD's resulted in a net reduction in power consumption. The net power saving achieved was 36,024 units/year (equivalent of 5.23 kW). The other major advantage is, the precise speed variation, which can be achieved.

Before Improvement After Improvement

to ensure better heat transfer. Steam soot blowers do this normally. The steam consumption of the steam soot blowers is very high and results in drop in efficiency of the boilers. Replacing steam soot blowers with Sonic (Acoustic) blowers, offers a viable option for reducing steam consumption and maintenance cost.

Advantages

• Savings in steam consumption• Less maintenance cost

11.7.6 Conversion to Fluidised Bed Boilers

Technology Description

The paper plant is a major consumer of thermal energy in the form of steam. This steam requirement is met by a battery of boilers fired by a solid fuel (coal) and also partly by the Soda Recovery Boiler (SRB) in the integrated plants. In the older paper plants, the conventional stoker boilers were in use. These boilers gave higher unburnts in ash and lower thermal efficiency. The latest trend is to install the fluidized bed boilers or conversion of the existing chain / spreader stoker boilers. The Fluidized Bed Combustion (FBC) boiler also enables the use of saw dust, which is generated in the chipper house.

Advantages

• Coal having high ash content / low calorific value can be used• Biomass fuels can also be used• Lesser unburnts in ash• Higher thermal efficiency

Case Study 4: Conversion of Spreader Stoker Boilers to Fluidised Bed Boilers

Brief

Energy savings

Annual savings @ Rs. 1.25/kg of coal : Rs. 11.5 MillionInvestment required : Rs. 27.0 MillionPayback period : 28 months.

11.7.7 Conversion of MP Steam Users to LP Steam Users to Maximize Cogeneration

Technology Description

The paper industry is a major consumer of power and steam. In all the integrated plants and in a few medium sized plants, the co-generation system is installed to

A large integrated paper plant had four numbers of spreader stoker boilers, operating to meet steam requirements of the plant. The steam generation was only 14 TPH, as against the design rating of 30 TPH. The boiler efficiency achieved was only 65 per cent.

Before Improvement After Improvement

Two of the four spreader stoker boilers were converted to fluidized bed combustion boilers. This conversion to fluidized bed combustion boilers enabled the use of sawdust, which is generated in the chipper house.Steam generation - 27 TPH Efficiency - 78% Coal Saving - 9239 T

357356

meet the power and steam needs of the plant simultaneously. The paper plant should make every effort to increase the co-generation power to the extent possible. The generation of power from the turbine depends on the pressure level of the extraction. The lower the pressure, the higher will be the generation of power per unit of steam extracted. Hence, efforts should be made to replace the HP (HighPressure) / MP (Medium Pressure) steam with LP (Low Pressure) steam to the highest extent possible.

Advantages

• Increase in co-generation power.

11.7.8 Deinking Process

Technology Description

Stringent guidelines for environmental protection and the social obligations of providing a clean environment is forcing paper mills to explore alternate raw materials and cleaner technologies for long term survival. Deinking process has emerged very promising in these aspects. Old Newsprints (ONP) and Old Magazines (OMG) form the raw materials for deinking. The process involves detachment of ink from the surface of the fibre and its removal through washing and floatation. Unit operations in deinking include Pulping, Screening, Floatation, Fine Cleaning, Slot Screening, Thickening, Dispersing, Bleaching & Final Storage. The waste paper is slushed with warm water and chemicals like Hydrogen peroxide, caustic, soaps etc. in the pulper and cleaned through "Contaminex" followed by HD cleaners before feeding to Floatation cell. The main task of floatation cell is to improve the cleanliness and brightness of the pulp stock. Air in the form of very fine bubbles is sparged through the stock. The ink particles stick to the air bubbles and float. The stock from floatation is pumped to the centri-cleaners for fine screening and further thickened in a Disk Filter. The stock is dewatered in a screw press to a consistency of 28% for final storage. Hindustan Newsprint Ltd. (Kerala) has successfully implemented this technology.

Advantages

• Lesser energy and water consumption, less pollution.

11.7.9 Pressure screens

Technology Description

The function of a pressure screen in a paper machine thin-stock recirculation system is to remove shives (fiber bundles) and other large, hard contaminants from the furnish. Conventional pressure screens use baskets with either slots or holes to admit the fibrous "accepts" flow and reject the contaminants. Slotted screens usually have a sculptured pattern that helps fibers to become aligned and pass through the screen. Pressure screens are equipped with various types of rotors to continuously redisperse any fibers that start to accumulate on the screen surface. Because fibers can pass through a slotted screen individually, but not as fiber flocs, papermakers sometimes choose to add retention aids ahead of pressure screens in order to achieve a favorable balance of formation uniformity and adequate retention of fine particles.

Advantages

• Reduced energy consumption, investment costs and improved cleaning efficiency.

11.7.10 Installation of Refiners (DDR/TDR)

Technology Description

In paper manufacturing process after thorough washing, bleached pulp is collected in a storage tank and finally pulp is refined through DDR (Double Disc Refiners) and TDR (Tri Disc Refiners) to make pulp suitable for paper making and to impart better fiber bonding condition which improves the physical strength of the paper. Installation of TDR in place of DDR is observed to give fine quality refining and is energy efficient. The technology has been successfully installed in ITC, Bhadranchalam.

Advantages

• Energy saving of about 150 kW can be achieved.

11.7.11 Black Liquor Recycling in Agro Based Mills

Technology Description

In the agro based mills, although chemical recovery system has been installed in few mills, but due to unfavourable properties of black liquors, the chemical and thermal recovery efficiencies are much lower than in wood based mills. One of the major constraints while processing the agro-based liquors in the chemical recovery section is the low solids concentration of the weak black liquors in comparison to the wood/bamboo liquors. This results in substantial quantities of additional steam requirements during black liquor evaporation in the chemical recovery to remove that extra quantity of water present in the agro based black liquors. Recycling of black liquor during pulping results in improved black liquor solids concentrations. In the recycling process certain portion of the fresh water is replaced with the black liquor during cooking of the agro based raw materials.

Advantages

• Improves the pulp yield by 1.0-1.5%, without bringing about any significant change in kappa values (A measure of the amount of lignin remaining in pulp after cooking) of the pulp.

• The net energy savings per tonne of pulp varies form 13-72 tonnes steam per day for a 100 tpd mill depending on the rise in solids concentrations.

• Black liquor recycling can be practiced in mills using wet cleaning systems by using improved dewatering devices.

11.7.12 High Capacity Chippers in the Chipper House and Mechanical Conveying in Place of Pneumatic Conveying.

Technology Description

Mills installed before 1980's have many small capacity disc chippers and the wood chips are transported from the chipper house located at the ground floor to the top of the digester house (at a height of about 12-15 m) for pulping operations. Conventionally, the chips were being transported pneumatically. The pneumatic conveying, though simple and easy to install, consumes more energy. Mechanical conveying is more energy efficient and consumes only about 25-30% of energy consumed by pneumatic conveying. Installation of a high capacity drum chippers belt conveyor can be taken up in those plants where the horizontal distance between the digester and chipper is sufficiently large. In case, if the horizontal distance is less and the inclination of conveying required is more, then a belt conveyor will not be suitable. In such cases, modified systems such as the crated belt conveyors can be installed.

359358

Advantages

• Lower specific power consumption• Mechanical feeding, leading to higher throughput• Uniform Chips size.

Case Study 5: Installation of High Capacity Chippers in the Chipper House

Brief

The recent technological advancements have led to the development of high capacity chippers. These chippers are provided with mechanical feeding mechanisms, enabling consistent feed to the chipper and high throughput from the chippers. This results in lower specific energy consumption of the chippers.

Energy savings

Annual savings @Rs.4.5/kWh :Rs. 5.9 MillionInvestment required :Rs. 24.0 MillionPayback period :49 months.

11.7.13 Dry Mechanical boosters in place of steam ejector

Technology Description

Steam ejectors find wide use in vacuum pumping applications such as in Vapour extraction, Chemical processing, Evaporative Cooling, Vacuum distillation, Vegetable oil de-odourization, Vacuum Refrigeration, Drying etc. In spite of the fact that steam ejectors have poor overall efficiency and relatively high-energy consumption, they are popular in vacuum applications because of their simplicity and ease of operation. Dry Mechanical Vacuum Booster offers an efficient replacement to steam ejector, for most of the applications as they overcome major drawbacks associated with steam ejectors.

Advantages

• Mechanical Vacuum Boosters are more energy efficient.

• Minimum of auxiliary equipment is needed; unlike for steam ejectors, which need large condensers, cooling towers, re-circulation pumps etc.

• Mechanical Vacuum Boosters are dry pumping system and don't give rise to water and atmospheric pollution.

• Startup time for mechanical booster is very low, making them ideal for Batch process operation where immediate startup and shut down is essential for energy conservation.

• Operating costs for mechanical vacuum systems are low, resulting in extremely short payback period.

11.7.14 Xylanases as Pre - Bleaching Agents During Paper Making

Technology Description

Concern for environment-friendly technologies has lead to refocusing on the chemical route of paper bleaching in pulp and paper industry. The use of Chlorine

Two numbers of high capacity drum chippers having lower specific energy consumption (about 7 kWh/ tonne) were installed in place of the earlier 5 numbers of the chippers.

A 750 TPD plant had 5 numbers of older, low capacity disc chippers in operation, with specific energy consumption of 12 kWh/tonne.

After ImprovementBefore Improvement

as a bleaching agent is causing concern as this produces dioxin and other chlorinated organic compounds, which contributes to AOX (absorbable organic halides) in the recipient streams. In the technology developed in IIT, Delhi, an enzyme prepared from a thermophilic fungus has been shown to act as an effective pre-bleaching agent on soft and hard woods. The level of chlorine was reduced by 15%. AOX release was also less. Pilot scale runs have been planned in collaboration with two paper mills.

Advantages

• The level of chlorine was reduced by 15% and lower AOX release was demonstrated.

11.7.15 High-Efficiency River Water Turbine Pumps for Raw Water Intake

Technology Description

Water is an essential commodity for pulp & paper industry, from both energy and environmental point of view. The overall water consumption of the Indian pulp and paper industry varies from 125 to 175 m3/ton of finished paper (depending on the product) in large integrated paper plants.

Advantages

• Efficiency of 87% possible. • Reduction in pumping power.

Case Study 6: Installation of High-Efficiency Turbine Pumps for Raw Water Intake

Brief

Water is an essential commodity for the pulp & paper industry from both energy and environmental point of view.

The overall water consumption of the Indian pulp and paper industry varies from 3125 - 175 m /ton of finished paper (depending on the product) in large integrated

paper plants.

Before Improvement

In one integrated paper plant, six pumps were installed at the raw water intake well to meet the raw water requirements of the entire plant. The pumps were of the following specification:

On detailed analysis of the pumps, it was observed that the three 125 HP pumps were operating very close to the design efficiency. On the other hand, the two 75 HP pumps were operating much below their best efficiency points. The design efficiencies were not being achieved, on account of ageing and wear out of impellers.

Capacity

Head

Motor rating

Design efficiency

3= 772 m /h

= 35 m WC

= 25 HP

= 86.5%

Capacity

Head

Motor rating

Design efficiency

3= 522 m /h

= 35 m WC

= 75 HP

= 80%

Three Pumps Three Pumps

361360

The total power consumption (measured by a common energy meter) of the 5 pumps in operation, before modification, was on an average 8000 units per day.

After Improvement

Three new high-efficiency, 125 HP turbine pumps were installed, in place of the old 75 HP turbine pumps. Substantial energy savings can be achieved by the installation of high efficiency turbine pumps.

After the installation of new high efficiency turbine pumps for raw water intake, the total power consumption (measured by a common energy meter) of the four pumps in operation was on an average about 7000 units/day.

Energy savings

There was a net reduction in power consumption by an average of 1000 units/day (equivalent to 41.7 kW).

Annual savings @ Rs. 4.5/ kWh = Rs. 1.6 MillionInvestment required = Rs. 1.5 MIllionPayback Period = 1 month

11.8 Case Studies

Case Study 7: Replacement of Suction Couch Roll by Solid Couch Roll in the Paper Machine

Brief

The paper machine performs the important function of converting the low consistency pulp to dry paper. The water removal is initially done by high-speed drainage, suction through flat vacuum boxes, suction couch & mechanical presses and drying in steam cylinders.

The latest paper machines have been installing the modern presses and reducing the load on the steam drying section. Another project, which has been taken up by some of the plants, is the replacement of the suction couch with the solid couch.The concept of this project is based on utilising the method, which removes the maximum quantity of water, with the least quantity of energy. This is particularly applicable to plants based on long fibre agro-pulp, which have a low drainage.

Energy savings

Annual savings @ Rs. 4.5 / kWh : Rs. 7.6 MillionInvestment required : Rs. 2.0 MillionPayback period : 3 months

In a medium size agro-based paper plant, the major portion of water from the wet end is removed by suction couch roll. The moisture removal is effected by a vacuum pump of 200 kW rating. This is a highly energy intensive process.The quantity of water removed by the suction couch is very low and the energy consumption was disproportionately high.

The suction couch roll was replaced by a solid couch roll for the efficient removal of moisture in the wet end of the paper machine.

The operation of the 200 kW vacuum pump was completely avoided with the implementation of this proposal.

After ImprovementBefore Improvement

Case Study 8: Utilisation of Bamboo Dust along with Coal Firing in the Coal Fired Boilers

Brief

Coal is used conventionally as the basic fuel for combustion in the boilers for steam generation. The steam requirements of the entire plant are met by steam generated in these coal-fired boilers. This is supplemented by steam generation from the soda recovery boilers.

Energy savings

Annual savings @ Rs. 1.25/kg of Coal : Rs. 4.14 MillionInvestment Required : MinimalPayback period : Immediate

Case Study 9: Installation of Centralised Compressed Air System

Brief

A centralized compressed air system has a single large / multiple number of compressors at one location. On the other hand, a decentralised compressed air system has multiple numbers of compressors, distributed over various locations. Centralised compressor system is preferred in cases where a large capacity requirement is needed at identical pressure levels.

Energy savings

Annual savings @ Rs.4.5/kWh : Rs. 2.0 MillionInvestment required : Rs. 1.0 MillionPayback period : 6 months

Case Study 10: Installation of Heat of Compression (HOC) Air Dryers

Brief

Compressed air is an important utility in process and engineering industries. Instrumentation applications require dry air. Any moisture present in the

Chipper dust was used to supplement the coal firing on a continuous basis except during the rainy season, due to the higher moisture content in the chipper dust. .With the use of bamboo dust as supplementaryfuel to the coal firing in the coal-fired boilers, there was a net annual reduction in coal consumptionby 3312 MT.

After ImprovementBefore Improvement

In an integrated paper plant, two coal-fired boilers met the majority of the steam requirements of the entire plant.There was lot of bamboo dust generated in the chipper house, which was being sold-off to outside parties.

After ImprovementBefore Improvement

A large integrated paper plant had two compressed air units catering to the compressed air requirements of the entire plant. These units were located at two different locations (decentralized).The decentralized system necessitates the operation of multiple compressor units. This leads to increase in both power c o n s u m p t i o n a n d m e c h a n i c a l maintenance problems.

The old compressed air pipelines were replaced with new pipelines, to reduce the leakage losses and line friction losses. Further, the compressors were located at one central location for ease of operation and maintenance.There was a substantial reduction in the leakage losses and significant savings of power. There was a net reduction in power consumption by 53 kW

363362

compressed air will condense at the point of utilisation causing damage to the instrumentation valves. Drying of compressed air is achieved through various methods. However, the latest trend is to install heat of compression (HOC) dryers.

Heat of compression dryer is a major technological improvement, having the following distinct advantages:

• Utilizes the heat in compressed air for regenerating the desiccant• Electrical heaters are eliminated• No purge air losses• Low atmospheric dew point is achieved depending on the desiccant used.

Energy savings

Annual savings @ Rs. 4.5/kWh : Rs. 0.7 MillionInvestment required : Rs. 1.48 MillionPayback period : 25 months

Case Study 11: Installation of Blind Drilled Rolls (Dri-Press Rolls) instead of Conventional Press Rolls in Press Section of Paper Machine

Brief

The press section has a very important role in the drying process and hence, steam consumption of paper machine depends upon the extent of mechanical dewatering. Many of the old paper plants, in general, have conventional press rolls for de-watering. This led to non-uniform moisture removal, which in turn affected the throughput through the system. This resulted in very high specific steam consumption in the paper machine.The recent technological advancements in water removal and increased runability of paper machines have led to the development of the blind-drilled rolls (or Dri-Press rolls).

An HOC dryer was installed alongside the existing dryer and utilised for drying of compressed air. The desiccant used was activated alumina, which can give an atmospheric dew point of - 40°C.Power savings achieved on account of the elimination of heater operation was 0.075 Million kWh/yr. Also, compressed air losses were totally avoided, as there are no purge losses in HOC dryers with savings of 0.08 Million kWh/yr.

After ImprovementBefore Improvement

A large integrated paper and board plant had compressed air requirements of about

3 3112 m / min. About 50 m /min of the compressed air was being dried using heater reactivated (lambda) type air dryer.The heater was rated for 32 kW heating capacity. The purge air loss in the dryer was about 10% of the total quantity of air being dried. This type of air dryer in addition to being highly energy intensive, also leadsto substantial quantity of compressedair losses.

The plant replaced the conventional press rolls with blind-drilled rolls in the two paper machines in phases.The dryness with blind-drilled rolls (for writing & printing paper) improved to 44-46%, as compared to 40-42% with conventional press rolls, thereby, achieving 2-6% improvement in dryness.This results in equivalent savings of 307 Tonne of steam consumption. Besides, there was tremendous improvement in machine run ability.

After ImprovementBefore Improvement

In a large integrated paper plant, the press section had the conventional press roll. The dryness achieved with the press roll was about 40-42%.Th i s s y s t em had the fo l lowing disadvantages:• Lower throughput• Increased de-watering

requirement• Higher downtime due to higher

breakages at wet end• Higher purging requirements • High specific steam consumption

Energy savings

Annual savings @ Rs. 3.00/kg of steam : Rs. 0.9 MillionInvestment required : Rs. 2.4 MillionPayback period : 32 months

Case Study 12: Installation of Extended De-lignification Pulping Process instead of Conventional Pulping

Brief

In a large integrated paper plant, the digester house had conventional vertical stationary digesters, having a combined capacity of 250 Tons of BD pulp/day.

The plant replaced the conventional vertical digesters with 3 new digesters of 80-tons/ day of BD pulp capacity, based on rapid displacement heating pulping process.

The reduction in chemical consumption was about 50%.

Energy savings

Annual savings : Rs. 140 MillionInvestment required : Rs. 500 MillionPayback period : 42 months

Case Study 13: Improved Paper Machine Design to Improve Production

Brief

The success of a paper mill is determined not only on the basis of quality and quantity of paper produced, but also on productivity. Efficiency of paper machine plays a vital role in achieving runability and hence, productivity.

Before Improvement After ImprovementSteam consumption 1.42 tons / ton of FNP 0.70 tons / ton of FNPBatch time 6 hours (avg. time) 4 hours (avg. time)Kappa number 21-22 12-13Yield 45.3% 46%

Washing loss 16 kg/ ton of pulp (as sodium sulphate)

10 kg/ ton of pulp (as sodium sulphate)

Black liquor conc. 14.2% 16%Ash retention 7% 10%Paper breakage 1.5%3.3%

Before Improvement

In an agro-residue based paper mill, renewable agro-waste, such as, wild grasses and straws were being used for making high quality writing & printing paper.

A critical study was conducted to modify its paper machine to improve its efficiency in terms of quality and productivity.

365364

Energy savings

Annual Savings : Rs. 18.3 MillionInvestment required : Rs. 5.0 MillionPayback period : 3 months

Case Study 14: Replacement of metallic blades with Fibre Reinforced Plastic (FRP) blades in cooling towers

Brief

Energy savings

Annual savings @ Rs.4.5 / kWh : Rs. 0.9 MillionInvestment required : Rs. 1.52 MillionPayback period : 20 months

Before Improvement After Improvement

Replacement of aluminium blades with lightweight FRP blades reduced the load on cooling tower fan motors & brought down energy consumption. With 3 nos of fan, total power consumption was 124.3 kW. After replacement, power consumption reduced to 98.7 kW with an annual total energy savings of 0.197 Million kWh.

A well-known paper manufacturing company had one centralized cooling tower consisting of 3 cells. The cells are fitted with fans having aluminium blades. The 3 cells of the cooling tower operate continuously. The fans are fitted with 55 kW motors. Metallic blades are heavy & consume more power.

After Improvement

The plant team applied various modifications, right from head box to dryer part in paper machine.The details of the modifications are as follows:

• Energy efficient rotary showers installed in head box, in place of stationary showers

• Wire circuit provided with an additional roll to improve wrap on FDR (Felt Drilled Roll)

• Motor used for wire return roll removed. Diameter of dandy rolls increased to 1200 mm to increase speed of paper machine, enhance production and provide for watermarks

• Ceramic tops installed in place of HDPE tops in paper machine• Suction pick-up roll modified to suction cum BDR (Blind Drilled Roll) to

avoid shadow marking and ensure better sheet dryness• Speed difference between wire and pickup roll reduced, resulting in

improved life of pickup felt life• SLDF (Spiral Linked Drier Fabric) screen replaced with woven screen for

better sheet flatness and prevent screen marking• Static current remover installed between calendar and pope reel

Case Study 15: Use of lighting voltage controller to reduce lighting energy consumption

Brief

Energy savings

Annual savings @ Rs. 4.5/kWh : Rs. 1.1 MillionInvestment required : Rs. 1.2 MillionPayback period : 13 months

Case Study 16: Replacement of desiccant (adsorption) type dryer with refrigerated dryer in compressed air systems

Brief

Energy savings

Annual savings @ Rs. 4.5/kWh : Rs. 1.4 MillionInvestment required : Rs. 1.0 MillionPayback period : 9 months

After Improvement

The dryer was replaced with a refrigerant type dryer, which consumes much less energy, as there is no desiccant to be dried.In the refrigerant type dryer, the air

ostream is cooled to nearly 0 C. In the process, it loses moisture to maintain the dew point.

3kW/1000m /h: 2.9 oDew Pt. C: 2 - 10

Purge: NilEnergy savings per hour by replacement of dryers: 37.75 kWh Operating annual hours: 8000Annual energy savings: 3.02 lakh kWh

Before Improvement

A paper manufacturing plant has 5 reciprocating compressors. The compressed air is generated at

27.4-7.6 kg/cm g. The compressed air in the plant is used primarily for instrumentation needs. The compressed air is needed to be dry for this usage and a desiccant type dryer was in use at the plant.The disadvantage with the desiccant type dryer is that energy is needed to drive off the moisture adsorbed by the desiccant. Though a much lower dew point (dryer air) can be obtained by this type of dryer, in this case, the dryer was over designed to provide much drier air than needed and was consuming energy unnecessarily.

3kW/1000m /h: 20.7 oDew Pt. C: -20

Purge: 10-15%

Before Improvement After Improvement

The plant lighting voltages were at a level, which could be brought down further. The installation of lighting voltage controllers, of different kVA, on each DB brought down the lighting consumption by 20%. The output voltages were set at 210 V.4 No. of DB lighting circuits had a total power consumption 338 kW. After installation, total power consumption came down to 275 kW with an annual total energy savings of 0.245 Million kWh.

A paper manufacturing plant has a connected lighting load of nearly 370 kW. This consists of fluorescent fittings, HPSV, HPMV & CFL lamps for plant, office and area lighting. The lighting load is fed from 3.3 kV bus by 4 nos. of LT transformers. These transformers have lighting loads apart from other loads. Each transformer is connected to a Lighting circuit Distribution box. The total actual load varies between 300 to 350 kW during night. Meters are fitted at each DB to measure power consumption. The voltage levels at lighting DBs vary between 225 & 240 V.

367366

Case Study 17: a) To conserve the electrical and thermal energy

b) To reduce the cost of production to compete and survive in the paper manufacturing field.

Brief

Energy savings Annual savings : Rs. 516 MillionInvestment required : Rs. 2030 MillionPayback period : 46 months

Energy savings

Increase in productivity : 33 MT/day to 40 MT/day

Power Consumption reduction : 720 kWh/MT to 640 kWh/MT.Steam Consumption reduction : 2.6 MT/Tonne of paper to 2.2

MT/Tonne of paper.

Case Study 18: Revamping of Paper Mill with new machinery, retrofitting &

capacity enhancement

Brief

Before Improvement After Improvement

The "Kakati" vacuum pumps were purchased and replaced. The driving motor was also replaced from 75 HP to 50 HP.

Flowbox of the paper machine was pressurized. The production of paper increased from 33 MT/day to 40 MT/day and power consumption was reduced drastically from 720 kWh/MT to 640 kWh/MT.

A new Thickener in the pulp mill was installed. It was found that the 5 HP motor was stopped due to recycling of thickener water.

A “Forbes Marshall" make Thermo compressor system was installed. It was found that the steam consumption came down drastically from 2.6 MT/Tonne of paper to 2.2 MT/Tonne of paper.

It is observed that the paper machine efficiency can further be improved to get more production with less power consumption per tonne of paper.

a)The Vacuum pump used in the paper machine was found to be less e f f i c i e n c y a n d m o r e p o w e r consuming.

b)The water consumption was seen to be in the higher side in the pulp mill.

c)The used steam in the paper machine coming out after passing through a series of dryer cylinders was found to be have more heat value for reuse. The vent out steam from dryercylinder was measured as 600 kg/hour.

Before Improvement After Improvement

Pulp Mill capacity enhanced to 300 TPD. Specific energy consumption improved to 14.93% of total mill consumption, a saving of 34.96 lakh units.

Free Flow Falling Film (FFFF) black liquor evaporators of 125TPH water evaporation capacity was installed.

Soda recovery boiler of 625 TPD solid firing capacity was installed.

New effluent free R8 process chlorine dioxide generation plant of 7 TPD capacity was installed.

Recausticizing and limekiln of 130TPD lime production capacity was installed.

Specific energy consumption of a 200TPD plant was 16.44 % of total mill power consumption.

High effluent treatment load and high consumption of resources.

L o w s t e a m e c o n o m y i n Evaporator.

Use of elemental chlorine for b l e a c h i n g w h i c h i s n o t environmental friendly and a power guzzler technology.

Case Study 19: Replacement of 4" pipeline by 6" pipeline for supplying Hot

Water to Wood Brown Stock Washers

Brief

Energy savings

Annual savings @ Rs. 4.5/kWh : Rs. 0.43 MillionInvestment required : Rs. 0.19 MillionPayback period : 5 months

Case Study 20: To down size Saveall Shower Water Pump impeller in MF

Machine

Brief

Energy savings

Annual savings @ Rs. 4.5/kWh : Rs. 45 MillionInvestment required : Rs. 0.1 MillionPayback period : 3 months

References

1. Annual Report - 2007-08, Ministry of Commerce & Industry, Department of

Industrial Policy & Promotion, GoI.

2. LBNL - 62806; World Best Practice Energy Intensity Value for Selected

Industrial Sectors, February 2008.

3. Statistical abstract - CSO

4. CII - IREDA Publication: "Investors Manual on Energy Efficiency".

Before Improvement After Improvement

Since the volumetric flow rate increased, the pressure drop was also higher in the 4” line. A 6” line replaced the 4” line and the pressure drop was reduced. The same quantity of water could be handled by single pump since the pump had the required capacity. There was a power saving of about 11.5 kW

In Pulp Mill Brown Stock Washers (BSW) were used for washing the cooked pulp. For this purpose hot water is used. Two pumps were provided each with the rating of 30 kW - one in service and the other as standby for supplying hot water to the washers. The wash water was supplied through 4” pipeline. As pulp production increased from 100 TPD to 140 TPD, more quantity of water was required for washing. To maintain the production level, both the pumps were put into operation consuming about34 kW.

Before Improvement After ImprovementThe performance curves of the pump were studied and it was found that the required duty conditions could be achieved by installing a lower diameter impeller.It was found that by replacing the impeller a saving of about 12 kW could be achieved.

MF 3 Paper Machine has a Polydisc Saveall for recovery of fillers and fines in the water and reuse of excess white water. The Polydisc Saveall has discs mounted with synthetic wire mesh that needs to be cleaned with high-pressure water. For this purpose a separate high-pressure pump is used. It was found that the high-pressure pump was oversized, as the system head was lower than the design head of the pump. This resulted in throttling of the valve at the delivery by about 35% to achieve the required flow rate and pressure.

368

5. Compendium of 'Energy Efficiency Workshop in Paper & Pulp Sector" by

BEE on 3rd September 2008 at Shaharanpur, U.P.

6. TERI Energy Directory and Yearbook 2007

7. Japan Energy Conservation Directory

8. LBNL - 54828: Emerging Energy Efficient Technologies in Industry case

studies of selected technologies - May 2004

9. LBNL - 57293; Assessment of Energy use and energy savings potential in

selected industrial sector in India, August 2005.

10. National Energy Map of India: Technology Vision 2030

11. Report of the working group on Power for 11th Plan (2007-12)

12. Report of the working group on R&D for the Energy Sector for the

formulation of the 11th Five Year Plan (2007-12)

13. BP Statistical Review, June 2008

14. www.energymanagemetnraining.com

15. www.cppri.org.in

16. www.eeii.org.in

369368

12.1 Introduction

India is the world's second largest cement producer after China, accounting for about 6% of the world's production. Annual per-capita consumption of cement in India is around 150 Kg, which is much lower than the global average of 270 kg. Cement is one of the core industries, which plays a vital role in the growth of the nation. Limestone and coal being the basic materials for cement manufacturing, India has the requisite quantity of cement grade limestone deposits, backed by adequate reserves of coal. India also has the requisite technical expertise to produce the best quality of cement with the most energy efficient processes. Many Indian companies have attained high levels of energy efficiency in their plants, which are comparable to international benchmarks.

For a variety of applications, various types and grades of cement are used. The most common types of cement are Ordinary Portland Cement (OPC), Portland Pozzolana Cement (PPC) and Portland Slag Cement (PSC). Indian cement industry produces various types of cements such as OPC, PPC, Portland Blast Furnace Slag Cement (PBFSC) or PSC, oil-well cement, rapid hardening - Portland cement, sulphate - resisting portland cement & white cement. In the year 2007-08, OPC production accounted for about 25% of the total production, while the blended cements, PPC & PSC accounted for 66% & 8% of the production respectively.

12.2 Present Capacity & Growth

India has 142 large & 200 mini cement plants. The total installed capacity of large cement plants in India is around 198 million tonnes per year & that of mini cement plants is 11 million tonnes. The cement production from large plants in the year 2007-08 was 168 million tonnes. The capacity utilization of cement plants in India is about 85%.

12.3 Manufacturing Process of Cement

Cement production involves the chemical combination of calcium carbonate (limestone), silica, alumina, iron ore and small amounts of other materials. Cement is produced by burning limestone to make clinker and the clinker is blended with additives and then finely ground to produce different cement types. Desired physical and chemical properties of cement can be obtained by changing the percentages of the basic chemical components i.e. CaO, Al O , Fe O , MgO, SiO , 2 3 2 3 2

etc..

Cement is manufactured from Limestone and involves the following unit operations:

• Mining• Crushing• Raw meal grinding• Pyro-processing• Cement grinding• Packing & dispatch

Chapter 12

Cement Industry

371370

Cement grinding

The clinker which is produced in the kiln is then grounded along with about 5% Gypsum to produce OPC. Ball mills have been generally used for grinding in cement plants in India either alone or in combination with roller press systems. In some of the recently installed plants, the VRM has been installed. The other types of cement such as PPC and PSC are also produced by grinding clinker with fly-ash and blast furnace slag respectively.

12.3.1 Clinker Production Process Technology

Clinker production is the most energy-intensive step, accounting for more than 80% of the energy used in cement production. Produced by burning a mixture of materials, mainly Limestone (CaCo ), Silicon Oxides (SiO ), 3 2

Aluminum, and Iron Oxides, clinker is made through three processes :

• Dry process ~ 97 % of the production• Semi-Dry process ~ 1% of the production• Wet process ~ 2% of the production

The Cement Industry today comprises mostly of Dry Suspension Preheater and Dry-Precalciner plants and a few old wet process and semi-dry process plants. Till late 70's, the Cement Industry had a major share of production through the inefficient wet process technology. The scenario changed to more efficient large size dry process technology since early eighties. In the year 1950, there were, only 33 kilns out of which 32 were based on wet process and only one based on semi-dry process. Today, there are 162 kilns in operation out of which 128 are based on dry process, 26 on wet process and 8 on semi-dry process. Basic principle of precalciner kiln is shown in figure 12.2:

Fig 12.2: Pre-Calciner Kiln

(Source : Understanding Cement; Website : thecementkiln.mhtml)

Raw Materials Preparation

Raw material preparation involves crushing of the quarried material, further raw grinding and blending the materials. The specific electrical energy consumption in raw materials preparation accounts for a significant part of overall electrical energy consumption.

Fig 12.1: Block Diagram of Cement Industry - (Dry Process Precalciner Process)

(Source : Investors Manual for Energy Efficieny, EMC, CII & IREDA)

Mining

The major raw material for cement manufacture is limestone, which is mined in open cast mines in the quarry and then transported to the crusher.

Crushing

The mined limestone is conveyed to the crusher through dumpers/ropeways/belt conveyors. The material is then crushed in the crusher to a size of about 25-75 mm. The crushing is done in two stages in the older plants while in the modern plants normally single stage crushing is done. The typical crushers used are jaw crusher and hammer crusher.

Raw meal grinding

The crushed limestone is grounded into fine powder in the dry condition. The Vertical Roller Mill (VRM) is comparatively more energy efficient than ball mill consuming only 65% of the energy consumption of the ball mill. The ball mill along with a pre-grinding system such as roll press is also used in some of the plants with very hard and abrasive limestone.

Pyro-processing

This takes place in the kiln system. The kiln is a major consumer of both the electrical and thermal energy in a cement plant. The calcination of limestone and the conversion into clinker takes place in the precalciner and kiln respectively.

Limestone

PurchasedCoal

373372

newer technologies and had thus remained at intermediate technology level. Also, the level of technology is not same at all the plants built during the same period.

Majority of the cement plants in the country are in the capacity range of 0.4 to 1.0 MTPA. These were set up more than 15-20 years ago and were based on the latest technology available at that time. Since then, numerous developments have taken place in the cement manufacturing technology.

Though some of the old plants have been modernized to a limited extent by retrofitting the new technologies, substantial scope still exists for adopting state-of-the-art technologies and bringing the old plants at par with world-class plants in terms of productivity, energy efficiency and environment friendliness, leading to cost competitiveness.

Moreover, the emission norms are likely to become more stringent in future and at the same time, the cement plants will be required to utilize waste derived raw materials and fuels to a large extent. The modifications of old plants to comply with these future requirements will also become inevitable. Therefore, there is a need to carry out a comprehensive assessment of all the earlier generation plants in the country to identify the extent of modernization required to improve their all round efficiency and enable them to meet the future criteria of viability, competitiveness and compliance with regard to energy consumption enabling them to comply with the provision of the Energy Conservation Act 2001.

12.3.4 Future Modernization Needs of the Indian Cement Industry

Although the industry has largely set up plants with energy efficient equipment, there are areas which require further improvements

• Appropriate pre-blending facilities for raw materials • Fully automatic process control and monitoring facilities including auto

samplers and controls.• Appropriate co-processing technologies for use of hazardous and non

hazardous wastes• Interactive standard software expert packages for process and operation

control with technical consultancy back-up• Energy efficient equipment for auxiliary/minor operations • Mechanized cement loading operations, palletization/shrink wrapping • Bulk loading and transportation, pneumatic cement transport• Low NO /SO combustion systems and precalcinersx 2

• Co-generation of power through cost-effective waste heat recovery system • Horizontal roller mills (Horo Mills) for raw material and cement grinding• Advanced computerized kiln control system based on artificial intelligence

12.4 Specific Energy Consumption in Cement Plants

Cement industry is highly energy intensive. The main source of energy is coal, followed by electricity. Energy accounts for almost 40% of the total manufacturing cost in some of the cement plants whereas Coal accounts for 15%-20% of the total cost.

The industry's average consumption in 2006-07 for dry process plants was 730 kcal/kg clinker thermal energy and 77 kWh/tonne cement electrical energy. It is

The energy used in the above three processes is given in table 12.1 below

Table 12.1: Energy Consumption

Source: Handbook of Energy Conservation by H.M. Robert & J.H. Collins

12.3.2 Technology Status of the Industry

A comparison of the status of the modernization in equipment and also the technologies absorbed or implemented by the Indian cement industry alongwith status of Global Technology is as under:

Table 12.2: Status of Technology

(Source : NCB)

12.3.3 Upgradation of Technology of Low Technology Cement Plants

The technological spectrum in the industry is very wide. At one end of the spectrum are the old wet process plants, while at the other end, are the new state-of-the-art technology plants presently being built by the Industry. In between these two extremes, are the large number of dry process plants built during the period 1965-90. These plants could not fully modernise or upgrade side by side with advent of

Item Wet Process

Dry Suspension Process

Dry Pre - Calciner Process

Heat Consumption (kcal / kg clinker)

1250 –1450 800 – 950

680 – 770

Power Consumption (kWh/tonne of cement)

100 – 115 100 - 105 70 – 95

Low Technology Plants Modern Plants Global Technology

Plant Size, TPD 300-1800 3000-6000 6000-12000

Mining & Material Handling

Conventional Computer aided Computer aided

Crushing Two stage Single stage In-pit crushing & conveying

Conveying of Limestone

Dumpers/Ropeway/ Tippers

Belt conveyors

Pipe conveyors, Belt conveyors

Grinding Ball Mills with / without conventional classifier

VRM’s Roll Presses with dynamic classifier

VRM’s, Roll Presses, Horo Mills with dynamic

classifier

Pyro Processing Wet

Semi Dry

Dry

-

4 stage preheater

-

Conventional cooler

-

Single channel

burner

Dry

-

5/6 stage

preheater

-

High

Efficiency

Cooler

-

Multi Channel

Burner

Dry

-

6 stage preheater-

High Efficiency Cooler -

Multi Channel Burner

-

Co-processing of WDF

- Co-generation of power

-

Low NOx/SO2

emission

technologies

Blending & Storage

Batch-Blending Silos

Continuous Blending silos

- Continuous

Blending

-

Multi-Chamber Silos-

Dome silos

Packing & Despatch

Bag

-

Bag

-

Bulk

-

Bulk

-

Palletizing & Shrink

Wrapping

Process Control Relay Logic / Hard Wired /

PLC - DDC

- Fuzzy Logic expert system

- DDC

- Neurofuzzy expert system

Energy consumption level

90-100 kWh/t cem. 900-1000 kcal/kg cl.

75-85 kWh/t cem. 700-800 kcal/kg cl.

70-80 kWh/t cem.680-725 kcal/kg cl

375374

12.5 Energy Efficiency measures adopted by Indian Cement Industry

12.5.1 General Measures

The Indian Cement Plants have achieved a high level of energy efficiency. The escalating costs of cement manufacturing over the years and increasing competitiveness have resulted in a focused approach by the cement industry in India to maximise the operational efficiency with respect to retrofitting of energy efficient equipment/systems, technology upgradation, process optimisation, effective maintenance management and above all, energy management including energy monitoring and energy audit. The comprehensive approach adopted by the Govt. of India, the National Council for Cement and Building Materials (NCB) and Cement Manufacturers Association (CMA) has resulted in significant reduction in specific energy consumption levels in cement plants.

NCB energy audit studies carried out in 36 Cement Plants during last five years indicated potential savings ranging from 4 to 210 kcal/kg clinker and 0.78 to 27 kWh/tonne cement. The estimated cost savings ranges between Rs 47 lakhs for 600 tpd plant to Rs 945 lakhs per annum for 4300 tpd for plant.

Major factors identified for higher energy consumption are

o• High preheater exit gas temperature (25-50 C higher)3• High preheater exit gas volume (0.1-0.4 NM /kg cl. higher)

• High pressure drop across preheater (upto 200 mmWG higher)• High moisture in fine coal (upto 5.8%)• Incomplete combustion of coal (CO - upto 1630 ppm)• False air infiltration in kiln and mill circuits (upto 20%)• Low heat recuperation efficiency of grate cooler (55-60%)

o• High cooler air exhaust temperature (upto 100 C higher)o o• High clinker temperature (upto 175 C against 90-100 C)

• Low efficiency of major process & cooler fans (<65%)• Under-loading (<50% kW loading) of motors resulting in low operating

efficiency

The potential savings identified in few plants are given in table-12.3 below :

Table 12.3: Potential Savings Identified

• kWh/t Clinker(Source : NCB)

Potential savings

Plant Kiln(s) capacity (tpd)and process (kwh/ton clinker) Thermal energy

kcal/kg clElectrical Energy

kWh/t CEMAnnual Savings

Rs Lakhs

1 1200 tpd, 6-ST, RSP Calciner 35 0.78 98

3800 tpd, 4-ST, PH & ILC 13 4.43 2692

3225 tpd, 5-ST, Double String Precal (Pyroclone) 38 2.11 2893

300 tpd, 4-ST Preheater 210 27 2394

6000 tpd, 6-ST, Double String Precal 32 1.30 4455

1800 tpd, 5-ST, PH & ILC 60 6.50 4086

2500 tpd, 4-ST, SLC Calciner (F L SMIDTH) 40 9.56* 5127

1215 tpd, 4-ST Preheater 45 14 3508

2400 tpd, 6-ST, Double String Preheater & Precalciner (Pyroclone)

22 5.68* 2959

3850 tpd, 5-ST PRECALCINER 68 5.98 58810

4000 tpd, 4-ST ILC Precalciner 11 5.52 336

11

3700 tpd, 5-ST, PC 70 5.40 89513

2400 tpd, 5-ST, ILC PC 36 4.95 28714

thexpected that the industry's average thermal energy consumption by the end of 11 Five Plan (Year 2011-12) will come down to about 710 kcal/kg clinker and the average electrical energy consumption will come down to 75 kWh/tonne cement.

The best thermal and electrical energy consumption presently achieved in India is 685 kcal/kg clinker and 71 kWh/tonne cement which are comparable to the best figures of 650 kcal/kg clinker and 65 kWh/tonne cement in a developed country like Japan.

The improvements in energy performance of cement plants in the recent past have been possible largely due to

• Retrofitting and adoption of energy efficient equipment• Better operational control and Optimization• Upgradation of process control and instrumentation facilities• Better monitoring and Management Information System• Active participation of employees and their continued exposure to energy

conservation efforts etc.

Various energy audit studies have estimated that at least 5 to 10% energy saving is possible in both thermal & electrical consumption through adoption of various energy conservation measures. It is estimated that the saving of 5 kcal/kg of thermal energy and 1 kWh/t cement of electrical energy will result in total savings of about Rs 6 Million per annum in a 1 Million tonne plant. The average energy consumption values by process for Indian cement plants vs the best world practice is given in Table 12.3 below:

Table 12.3 : Average and Best Practice Energy Consumption Values for Indian Cement Plants by Process.

(Source: Cement Manufacturer's Association 2003; Worrell 2004)

Process Unit IndiaAverage

WorldBest Practice

Raw Materials Preparation

Coal mill

kWh/t clinker

8

2

Crushing

h/t clinker

2

1

Raw mill

h/t

clinker

2 2

Clinker Production

Kiln & cooler

kcal/kg of clinker

77

6

Kiln & cooler h/t clinker 2

2

Finish Grinding Cement mill

h/t

cement

3

2

Miscellaneous

Utilities: mining &

transportation

h/t clinker

1

6

1

.

Utilities: packing house

h/t cement

1 1

Utilities: misc. h/t cement 2 1

Total Electric h/t cement 9 7

kW

kW

kW

kW

kW

kW

kW

kW

377376

covering the need for drying energy, there is still waste heat available which can be utilized for electrical power generation thereby making additional power available and reducing CO emission.2

The cement industry is yet to adopt the cogeneration technology due to various technical, financial and institutional barriers. Recently, a model demonstration project has been jointly implemented by New Energy and Industrial Technology Development Organisation of Japan (NEDO), and Govt. of India under Green Aid Plan (GAP). The system has been installed on a kiln of 4550 tpd clinker capacity with 4 stage suspension preheater and precalciner. The exhaust gas flow through

3 opreheater (PH) boiler is of the order of 3,60,750 Nm /hr at 340 C whereas through 3 oAir Quench Cooler (AQC) boiler, it is 1,96,000 Nm /hr at 360 C. The power

generated is of the order of 7700 kW at 6.6 KV. The installation cost of the system is around Rs 84 crores. The economic efficiency analysis indicates reduction of :

6• 56.07x10 kWh of power purchased - Rs 24 crores• Fossil fuel consumption of 14517 tonnes/year• CO emission of about 45098 tonnes/year2

Case Study 1 : Installation of High Efficiency Dynamic Separator for Raw Mill

Brief

In a million tonne dry process pre-calciner plant, the existing static separator of the VRM was replaced with a new cage type dynamic high efficiency separator.

There was an increase in the output of the Mill, finer product and reduction in the specific power consumption of the Mill. Additionally, the Mill vibration also got reduced resulting in trouble free operation.

The Power Saving amounted to 2.5 units/tonne of Raw meal or 3.0 units/tonne of cementEnergy Saving

Annual Energy saving : Rs 1.8 Million kWhAnnual Savings : Rs 270 MillionInvestment : Rs 300 Million Simple payback : 13 months

Case Study No. 2: Savings in Electrical Energy by increasing Kiln String Cyclone Diameter from 5.4 Mts to 6.6mts

Brief

Parameter

Before Implementation

After Implementation

Saving/Improvement

Cyclone dia. (m)

5.4

6.6

Pressure drop (MMwg)

115

86

( - ) 29

Energy consumption kWh

750 722 ( + ) 28

Kiln output (TPD) 6281 6597 ( + ) 316

Some of the energy efficiency measures implemented in different cement plants in India are:

(i) Operational Control and Optimisation

Process optimisation, load management and operational improvement generally involve marginal financial investment and yet found to have produced encouraging results in energy saving. The different aspects explored in this direction are :

• Plugging of leakages in kiln and preheater circuit, raw mill and coal mill circuits• Reducing idle running of equipments • Installation of Improved insulating bricks/blocks in kilns and preheaters• Effective utilisation of hot exit gases• Optimisation of cooler operation• Optimum loading of grinding media/grinding mill optimisation• Rationalisation of compressed air utilization• Redesigning of raw mix• Installation of capacitor banks for power factor improvement• Replacement of over-rated motors with optimally rated motors• Optimisation of kiln operation• Changing from V-belt to flat belt

(ii) Energy Efficient Equipment

Use of energy efficient equipment gives very encouraging results even at the cost of some capital investment. More and more plants are now going for these available energy saving equipment to improve the energy performance of the units. The energy efficient equipment being used by the cement industry are :

• Slip Power Recovery System• Variable Voltage & Frequency Drive• Grid Rotor Resistance• Soft Starter for Motors• High Efficiency Fans• High Efficiency Separators• Vertical Roller Mill• Pre-Grinder/Roller Press• Low Pressure Preheater Cyclones• Multi-channel Burner• Bucket Elevator in place of pneumatic conveying• Fuzzy Logic/Expert Kiln Control System• Improved Ball Mill Internals• High Efficiency Grate Cooler

(iii) Waste heat recovery for cogeneration of power

In case of dry process cement plants, nearly 40 percent of the total heat input is rejected as waste heat from exit gases of preheater and cooler. The quantity of heat lost from preheater exit gases ranges from 180 to 250 kcal/kg clinker at a

otemperature range of 300 to 400 C. In addition, 80 to 130 kcal/kg clinker heat is lost oat a temperature range of 200 to 300 C from grate cooler exhaust. The waste heat

has various applications such as drying of raw materials and coal, but even after

379378

Case Study No.5: Installation of new correct head pump for raw mill slurry transfer to Silo

Brief

Suppose that there are 3 raw mills, out of which 2 to 3 are in normal operation. Limestone slurry from the raw-mill section is pumped to the low-grade silos. There are two slurry pumps of different capacities to meet the carrying capacity requirements.

The specifications of the two slurry pumps are as follows

The large pump is operated, when 2 raw mills are in operation, while the smaller pump is in operation, when for 1 raw mill is in operation. On comparing the two pumps, it is evident that the larger pump is designed with a higher head. The maximum head required for the slurry pump is :

Silo Height : 16 m Pit Height : 4 m Line loss : 3 m Additional height : 2 m

It is recommended to install new correct head pump for slurry transfer from raw mill to LG silos, using the existing pump as standby.

Actual head required for pump : 4 m (Pit height) + 16 m (Silo height) + 2 m (Additional height) + 3 m (Line loss) = 25 m (Say 30 m )

With one mill in operation & smaller pump started - head is only 20m. With 2 or 3 mills, bigger pump is operated & here the head is very high.

Capacity required with 3 mill 3Operation = 175 m /h (Same as existing)

3 3Maximum power consumption = 175 m /h x 30m x 1.69 kg/m ) 102 x 3.6 x 0.70 pump x 0.85 motor= 40.61 (Say 41 kW)

Annual Savings = (54-41) kW x 8000 kWh x Rs. 2.26/kWh= Rs 0.235 Million

Energy Saving

Annual savings : 0.235 MillionInvestment required (for new pump & motor) : 0.120 MillionPay back period : 6 months

Case Study No.6 : Replacement of Existing Cyclones with Low Pressure Drop (LP) Cyclones

Description

Smaller capacity pump

Larger pump capacity(54 KW)

Head Capacity

20 m

40 m

-

3175 m / h

Energy Saving

Energy Savings : 28 kWhAnnual Savings : Rs 0.88 MillionInvestment : Rs 2.2 MillionPayback period : 2.5 years

Case Study No. 3: Optimisation of Crusher Output

Brief

The average output of Crusher is 205 TPH. The major constraints were the capacities of belt conveyor from Primary crusher to secondary Crusher.

The feed was restricted due to spillage taking place at the belts. It was possible to increase the width of the belt and speed after changing the gear boxes.

The capacity of belt was increased from 200 TPH by enlarging the belt size and gearbox.

Energy Saving

Case Study No.4: Replacement of the Air-lift with Bucket Elevator for Raw-meal transport to the Silo

Brief

The air-lift was replaced with a bucket elevator. The air-lift was retained to meet the stand-by requirements.

The implementation of this project resulted in reduction of power from 140 units for the air-lift to 40 units for the Bucket elevator. The air to be ventilated from the silo also got reduced with the installation of the mechanical conveying system. The silo top fan was downsized to tap this saving potential.

Low energy consumption (25 - 30% of Pneumatic conveying)Reduction in power consumption of silo top dedusting system

Energy Saving

Annual Energy Saving : 0.68 Million kwhAnnual Savings : Rs 2.24 MillionInvestment : Rs 5.4 MillionSimple payback : 29 months

Parameter Before Implementation

After Implementation

Saving/Improvement

Output of crusher (TPH)

205 235 ( + ) 30

Energy consumption kW h / tonne

2.1 1.8 ( - ) 0.3

Annual saving (Rs.) - - ( + ) 66000

381380

Savings in power consumption : 3.1 kWhAnnual savings : Rs 0.1 MillionInvestment : Negligible Payback period : Immediate

Case Study 8 : Variable Speed Fluid Coupling for Cooler ID Fan and replacement with lower capacity motor

Brief

A Variable Fluid Coupling (VFC) was installed for the Cooler ID fan. The hood draught was maintained by varying the speed through the VFC. The existing 315 kW, 750 rpm & 6.6 kV motor was replaced with a 230 kW, 750 rpm & 6.6 kV motor.

There was a drastic reduction in the power consumed by the Cooler ID fan. The comparison of the conditions and the power consumption before and after installation of the VFC are as below:

Energy Saving

Power consumption with damper control : 123 kWPower consumption with VFC : 76 kWEnergy saving : 47 kW Annual Energy saving : 0.384 Million kWhAnnual Savings : Rs 1.15 MillionInvestment : Rs 0.5 MillionPayback period : 5 months

Case Study 9: Delta Start Star Run Operation of Dust Collector

Brief

i) The Dust Collectors are installed in the cement plant for collection of dust emission. The dust collector is provided with the filter bags and blower motor. The dust is collected in the bags and prevented from going in the air to control air pollution.

ii) It was observed during analysis of drive loading that the Dust Collector motor was operating below 50% loading. The loading on the motor has been reduced due to optimization of dust collector and pipelines bends. The starting torque requirement of the equipment is high hence Delta start and star run arrangement was suggested to reduce the power consumption.

Energy Saving

Unload (kW) Load (kW)

Power consumption

111 24 72 18

90 16

Timings

Load (S) Unload (S)Cement Mill

D-Pump

Average unload = 17 %

CompressorBrief

Implementation methodology & time frame: The top cyclone was at a height of nearly 106 metres. The implementation of this project involved removal of the existing cyclone and fixing of the new LP cyclone.

The replacement lead to an increase in the output of the Kiln, reduction in pressure drop of the pre-heater, reduction in Kiln section power consumption and reduction in Kiln specific thermal energy consumption. The comparison of the conditions and the energy consumption before and after installation of the LP cyclones are as below:

Energy Saving

Annual Savings : Rs 2.4 Million

Investment : Rs 2.2 Million

Payback period : 11 months

Case Study 7: Derating Compressors to optimize the unload power consumption

Brief

The Filteration plant instrument compressor is observed to unload for 22% of time. Power consumption measurements indicate that the load power consumption is 22 kW and the unload power consumption is 7 kW.

The cement mill D-pump compressor was found to unload for 17% of time. The load and unload power consumption was measured to be 111 kW and 24kW.

It was recommended to derate cement mill D-Pump compressor & filtration plant instrument compressor by 10%. The compressor drives were belt driven and derating was carried out by changing the pulley size suitably.

Parameter Before Implementation

AfterImplementation

Benefits

Clinker Production (TPD)

DP across Top Cyclone (mmWg)

Kiln section Power (kWh/T)

Heat Consumption (kcal/kg)

2650

100

–

125

30

830

2850

70

–

90

28.5

810

( + ) 200

( - ) 30-35

( - ) 1.5

( - ) 20

69 17

71 23 22 7Average Unload = 22 %

Compressor Timings Power consumption

Load (kW) Unload (kW) Load (S) Unload (S) Filtration plantInstrumentationCompressor

Energy Saving

Annual energy saving : 0.46 Million kWhAnnual Savings : Rs 1.5 MillionInvestment : Rs 2.5 MillionPayback period : 20 months

Case Study 11: Installation of Variable Frequency Drive for MFC Fluidizing Air Blower

Brief

3The Blower used for fludisation air is of the following specifications - 165 m /hr flow, 1000 mm WC pressure rise and 40kW motor rating - for supplying fluidizing air. The actual power consumption of the fan is 37 kW.

The suction area of the fan is about 70% closed and the inlet guide vane is controlled to the extent of 70% open. This indicates that the rated flow is much higher that actual requirement.

After installing the VFD, open the suction area fully and gradually reduce the rpm till the discharge pressure is the same as before. Subsequently, open the IGVcompletely to 100% open position and further reduce the speed of the blower till the pressure difference across the blower is maintained at present values.

3Blower specification (WC) : 165 m /h, 1000 mm Motor Rating (kW) : 40

Energy Saving

Energy savings : 0.3 x 37 kW = 11.1 kWAnnual savings : Rs 0.37 MillionInvestment : Rs 0.35 MillionPayback period : 11 months

Case Study 12 : Replacement of Existing Cooler I Grate with High Efficiency Cooler System

Brief

The plant replaced the I grate with high efficiency cooler system. This was done to increase the capacity of the Cooler and also improve the thermal efficiency of the system. Additionally the following capacity upgradation measures were also implemented simultaneously :

• Increasing the height of the Calciner• Installation of high efficiency classifier for both Raw mill and Coal

Mill• Conversion of the existing two fan system to three fan system• Installation of high efficiency nozzles for GCT

On account of the capacity upgradation projects the capacity of the Kiln increased from 2800 TPD to 3000 TPD. The installation of the high efficiency Cooler resulted in reduction in the Cooler air quantity and cooler exhaust air

iii) The Delta start and star run operation of the motor was technically viable, as the motor will operate in equipment safe operation and energy saving mode. The star operation of the drive will reduce the loading of the motor with reduction in copper losses and improvement in the efficiency of the motor. The PLC logic was prepared to start the motor in delta mode and shifting to star mode when full speed was pick up by the motor. The financial implications are nil, as no capital investment needed.

Energy Saving

Case Study 10 : Variable Frequency Drives for Cooler Fans

Brief

Four cooler fans were installed with Variable Frequency Drives (VFDs).There was a drastic reduction in the power consumed by the Cooler fans. The power saving in the fans is on account of

• Saving in the energy lost across the dampers• Increase in the operating efficiency of the motor. The efficiency of the

motor depends on the V/f ratio. In the case of the VFD, the voltage is varied to maintain the V/f ratio at the designed value. Hence, theefficiency of the motor is maintained at a higher level even at lower loading of the motor.

The comparison of the conditions and the power consumption before and after installation of the VFDs are as below:

kW SAVINGSno. Perticulars Before After

Modification Modification Saving

(A)

1 Operation Delta mode Star mode

2 Power Intake /Hr. a) Load Current 20.9 AMPs 15.4 AMPs

b) Power Factor 0.93 0.98

c) Voltage 400 Volts 400 Volts

d) Power (1.73 xVxIxP.F) 13.46 kWH 10.46 kWH

3 Saving in KW 13.46 10.46 3 kw

13.46

10.46

0

20

DELTA STAR

Equipment Rating (kW) Power consumption

before VFD

Power consumption

after

VFD

Savingthrough

VFD

Fan

–

IA (kW)

Fan

–

IB (kW)

Fan

–

IC (kW)

Fan

–

IC (kW)

75

75

110

110

45

44

68

59

32

30

54

44

13

14

14

15

Total Saving (kW)

- 57

383382

385384

3m /min of flow 500 mm pressure rise with a motor rating of 470 kW. The measured power consumption of this fan is 270 kW.

The Recirculation fan flow was controlled by damper . This indicated the excess capacity/head availed in the fan. The damper opening was observed to vary from 45% to 80% depending on the separator output.

At 80% of the damper opening (the normal maximum damper opening), the damper is observed to offer a pressure drop of 18.9%. This indicates that 18.9% of the power consumed by the fan is lost across the damper.

The capacity of the fan cannot be permanently derated because the capacity of the fan needs to be varied with time.

It was concluded that good energy saving potential exists by installing a speed control device and varying the speed of the fan.

Hence, it was required to install a Grid Rotor Resistance (GRR) control to the recirculating fan and vary the capacity as required. The damper must be fully opened once the GRR is installed to the recirculating fan. Damper position of recirculation fan varies from 45% to 80% opening based on the separator output.

At 80% damper opening, damper loss is calculated

Damper loss = -320 - (-390) -20 - (-390)

= 18.9%Actual power consumption = 270 kW

Install a GRR and vary the speed of the fan instead of the damper position. Measured Savings, after considering GRR's power consumption (kW) : 51.

Energy Saving

Savings in power consumption (kW) : 30 Annual savings : Rs 0.64 MillionInvestment : Rs 0.5 MillionPayback period : 10 months

Case Study 15: Reducing the Speed of Cement Mill's Dust Collection Fan

Brief

A Cement Mill's dust collection fan was observed to operate with damper control. The damper was open to the extent of about 40%. Pressure measurements before and after the damper and at the fan delivery indicated that the pressure drop across the damper is about 73%. The motor rating of this fan is 22 kW and the measured power consumption of the fan is 17 kW.

The pressure loss of 73% across the damper indicates that nearly three-fourth of the power consumption of the fan is lost across the damper.

Good potential for energy saving exists by reducing the speed of the fan.

quantity. There was also an improvement in the steady operation of the Kiln, better quality and lower temperature Clinker. The over-all benefits achieved are as below:

Energy Saving

Annual Savings : Rs 12 MillionInvestment : Rs 29 MillionPayback period : 30 months

Case Study 13: Usage of High Efficiency Crusher as a Pre-grinder before the Cement Mill

Brief

The plant installed a Horizontal Impact Crusher (HIC) of 300 TPH capacity (including recirculation). The HIC was to act as a pre-grinder and perform the initial size reduction before the Mill. The HIC had a three deck-vibrating screen to separate and return the coarse material back to the HIC. The coarse was sent to the HIC back by gravity while the fines were conveyed to the hopper through a belt conveyor. The fines from the hopper can be later fed to the Mill through a belt conveyor. Thus the HIC and the Mill were made independent so that the operation of one does not affect the other.

Energy Saving

Increase in capacity from 125 TPH to 175 TPHReduction in power consumption from 29.0 units to 25.7 units per tonne of O P C - 4 3

Annual Savings : Rs 15 MillionInvestment : Rs 40 MillionSimple payback : 32 months

Case Study 14: Installation of Grid Rotor Resistance (GRR) Control and varying the Speed of the Recirculation Fan

Brief

The Cement mill is a close circuit mill. The recirculation fan in the cement mill draws air from Separator through Cyclone. The recirculation fan is rated for 3800

Parameter Before Implementation After Implementation

Clinke Production TPDr

3Cooler air Nm /kg

PH outlet air 3Nm /kg

0Clinker Temperature C

PH outlet Temperature 0 C

PH loss kCal/kg

Cooler & Clinker loss kCal/kg

Radiation loss kCal/kg

Heat Consumption kCal/kg

2800

2.6

1.475

180

370

217

131 69

780

3000

2.1

1.444

120

336 191 120 65

745

Savings/Improvement

( + ) 200

( - ) 0.5

( - ) 0.031

( - ) 60

( - ) 34

( - ) 26

( - ) 11

( - ) 4

( - ) 35

387386

Table 12.5: 'Primary Energy Intensity Values' for Cement Plants following World Best Practice.

(Source : World Best Practice Energy Intensity Values; LBNL; Worrell E., Price L., Neelisy Galitsky C.)

12.7 Other Best Practices of Energy Efficiency in Cement Industry

Some of the best ENCON practices being used in cement industry Internationally are:

i) Raw Material Preparation

• Mechanical conveyors, in place of pneumatic conveyers, which consume 2 kwh/t less energy for dry process.

• On line analysers used for raw mix control. • Gravity type homogenizing silos (or continuous blending & storage silos)

reduce power consumption by 0.9 - 2.3 kWh/t raw material.• Reduction in compressed air losses by plugging of leakages in slurry

blending & homogenizing (wet process).• Replacement of tube mill by a wash mill in wet process leads to reduction in

electricity consumption by 5-7 kWh/t.• High efficiency vertical roller mills in place of balls mills, saves energy of

6-7 kWh/t raw material. • A multi variable controller in vertical roller mills to maximize the total feed

while maintaining a target residue and enforcing a safe range of trip-levelvibration. The throughput increases by 6% and SEC reduces by 6% or 0.81.0 kwh/t of raw material.

• Using high efficiency classifiers or separators, the material stays longer in the separator, leading to shaper separation, thus reducing over - grinding & saving 8% of electricity.

ii) Fuel Preparation

- Installation of roller presses for coal grinding in place of conventional grinding mills.

iii) Clinker Production

a) Wet Process :

• Wet process conversion to semi-dry process through slurry gas driers. Evaporation energy is reduced to half in this process, reducing fuel consumption by 1 MBtu/t clinker.

• Wet process conversion to semi-wet process by installing filter press to reduce moisture content to about 20% of the slurry and obtain a paste, ready for extrusion into pellets.

Cement

Unit

GJ/t

Kgce/tPortland Cement t Cement 3.4 115Fly Ash Cement t Cement 2.5 84Blast Furnace Slag Cement t Cement 2.1 73

Reduce the speed of the fan by 30%. The speed reduction should be done in stages of 10% each. This fan being a belt driven equipment, the speed reduction could be carried out by pulley size reduction.

Loss across damper = -48-(-175) (All measurements in mmWC) = 73 % -1-(-175)

Energy loss = 0.73 x 17 kW = 12.4kW

By reducing the speed of the fan by 30%, 50% savings in energy Consumption is possible.

Energy Saving

Savings in energy consumption : 8.5 kWAnnual savings : Rs. 66,000 Investment : Rs. 10,000/-Payback period : 2 months

12.6 Energy Consumption in Cement Plants - World's Best Practice

The specific energy consumption of cement plants in developed countries like Japan is 650 kcal/kg of clinker as thermal energy and 65 kwh / tonne of cement as electrical energy. This is mainly because of advanced technologies, process designs and best energy efficiency practices adopted. The 'World's Best Practices represent the most energy efficient processes that are in commercial use in at least in one location, worldwide. The Energy Intensity values are defined as:

(i) "Final Energy Intensity Values", i.e. the energy used at the production facility

(ii) "Primary Energy Intensity Values" i.e. the sum of energy used at the production facility, plus the energy used to produce electricity consumed at the facility.

The process in cement plant based on the energy consumption can be divided into following parts: -

a) Raw materials preparation (limestone & fuels).b) Clinker making (fuel use & electricity use)c) Additive dryingd) Cement dryinge) Other energy uses (quarrying, auxiliaries, conveyers and packing)

The World Best Practice Values based on the above processes for 'Final Energy' and 'Primary Energy' are given in tables 12.4 & 12.5 for Portland Cement, Fly Ash Cement and Blast Furnace Slag Cement respectively.

Table 12.4: 'Final Energy Intensity Values' for Cement Plants following World Best Practice.

*kgce = kg of coal equivalent(Source : World Best Practice Energy Intensity Values; LBNL; Worrell E., Price L., Neelisy Galitsky C.)

Cement

Unit

GJ/t

*kgce / t

Portland Cement t Cement 2.9 100Fly Ash Cement t Cement 2.0 70Blast Furnace Slag Cement t Cement 1.7 57

389388

v) Plant-wide measures

• Preventive maintenance of the plant.• Use of High - Efficiency Motors & Drives.• VFDs for clinker fans, fans in kiln, cooler, pre heater, separator and mills.• Reduction is losses in compressed air system.• Energy Efficient lighting.

12.7.1 The energy efficiency measures in 'Dry Process Cement Plants' in US

Energy Efficiency Measures in Dry Process Cement Plants are summarized in table 12.6. The estimated savings and payback periods are averages for indication, based on the average performance of the U.S. cement industry (e.g. clinker to cement ratio). The actual savings and payback period may vary by project, based on the specific conditions in the individual plant.

Table 12.6 : Energy Efficiency Measures in Dry Process Cement Plants

Notes: Payback periods are calculated on the basis of energy savings alone. (Source : Energy Efficiency Improvement Opportunities for Cement Making; An Energy Star Guide; LBNL; by Worrell E., Galitsky C.)

Energy Efficiency Measure Specific FuelSavings

(MBtu/tonne

SpecificElectricity

Savings (kWh/tonne

EstimatedPayback Period

(1) (years)

0.16 – 0.4-

Fuel Preparation: Roller Mills - 0.7 – 1.1 N/A (1)Clinker MakingEnergy Management & Control SystemsSeal Replacement

Combustion

System

Improvement

Indirect

Firing

Optimize Grate CoolerConversion

to

Grate

Cooler

Heat Recovery

for

Power

Generation

Low-pressure

Drop

Suspension

Preheaters

0.10 – 0.20

0.02

0.10

–

0.39

0.09 – 0.310.06-

0.12

0.23

-

- > 0.5

1.2 – 2.6

-

-

-0

– (-1.8)

-2.4

18

0.8

–

3.2

-

1 – 3

< 12 – 3

11 – 21 – 2

3

11

Finish

Grinding Energy

Management

&

Process

Control

Improved Grinding Media in Ball Mills

-

-

1.6

1.7

–

6.0

< 1

> 10 (1)Plant Wide

Measures

Preventative

Maintenance

High Efficiency MotorsAdjustable Speed DrivesOptimization

of

Compressed

Air

Systems

0.04

---

0

–

5

0 – 55.5 – 7.0

0

–

2

< 1< 12- 3< 3

Product

Change

Blended

Cement

Limestone

Portland

Cement

Use of Steel Slag in Clinker (CemStar)Low Alkali CementReduced Fineness of Cement for SelectedUses

1.21

0.30

0.16

-153.0-

0 – 14

< 1< 1< 2

N/A ImmediateImmediate

• Wet process conversion to dry process production by installing multi - pre heater / pre - calciner. Fuel saving of upto 2.9 MBtu/ ton can be achieved.

b) Dry Process pre-heater Kilns :

• Low pressure drop cyclones for suspension pre - heaters can save 0.6 - 0.7 kWh/t clinker for each 50mm WC (Water column).

• Heat recovery from the kiln exit gases for co-generation, either by installing direct gas turbines that utilize the waste heat (top cycle) or by installing waste heat recovery boiler system that runs a steam turbine system (bottom cycle). Power generation may vary from 10 to 23 kWh/t clinker, saving electrical energy of 20 kWh/t clinker.

• Dry process conversion to multi - stage pre - heater by installing multi stage suspension pre heating (4 or 5 stage) reduces heat loss and thus increases efficiency. Kiln length is also shortened by 20% to 30%, thereby reducing radiation losses.

• Conversion of Long Dry Kilns to multi - stage pre heater / pre calciner kiln can save 1.2 MBtu / tonne clinker.

c) Other measures :

• Advanced process control through online analyzers to recover heat from kilns (e.g. 'fuzzy logic' or 'ABB LINKman' control system) to save 2.5% - 5% energy and reduce NOx emissions by 20%.

• Gyro - thermal technology for kiln construction system improves gas flame quality while reducing NOx emissions.

• Oxygen enrichment in the kiln to increase production capacity.• Upgradation of pneumatic seals at the kiln inlet and outlet reduces false air

penetration as well as heat losses.• Use of better insulating refractories with high temperature insulating

lining reduces kiln shell heat losses thereby saving 0.1 - 0.34 Btu/ton fueluse.

• Use of high efficiency AC variable frequency drives in place of DC drives for rotating the kiln.

• Use of VFD in kiln fan reduces 40% of energy.• Replacement of rotary or shaft coolers by Reciprocating Grate coolers in

the cooling of clinker and efficient heat recovery (almost by 65%) saves about 8% of the fuel consumption in the kiln.

• Optimization of heat recovery by using reciprocating grate coolers for large kilns (upto 10,000 tpd) for recovery of sensible heat upto 1.4 MBtu/t.

iv) Finish Grinding

• Process control and management of Grinding mills. • Advanced grinding concepts by installing high pressure roller presses.• Use of high efficiency classifiers increases production by 20% to 25% and

reduces 8% electricity. • Improved wear grinding materials such as chromium steel can be installed

for grinding media. Potential savings 5% to 10%.

391390

2) The roller mill mechanism is primarily to crush coal between the disc table and rolls which are pressed hydraulically onto the table.

3) Ground coal is fed upward to the classifier placed above by the hot air blown into the mill from below. Coal is dried while it is being brought upward by the hot air.

Use of the vertical roller mill can reduce specific consumption of electric power by 20 to 25 percent compared with the conventional combination of tube mill and separator.

Energy Saving

Investment amount : Rs. 250 Million for 20 tonne/hour sizeImprovement Effect : Reduction of SEC by 20% - 25%

(c) Adoption of high-efficiency quenching cooler

Brief

This modification represents adoption of a high-efficiency quenching cooler. The high-efficiency quenching cooler rapidly cools burned clinkers from the kiln by air to improve the cement quality. At the same time the air heated by the burned clinkers is used as combustion air for kiln burner to achieve energy saving.

Modification: Modification into high-efficiency cooler with the capacity of 5,000 tonne / day

Energy Saving

Energy saving effect of clinker cooler

Case Study 18 : Cement production finishing section :

Brief

The present case installs a vertical roll crusher of high grinding efficiency as a pre-grinding crusher in the step previous to the ball mill, the finishing grinder of cement. Crushing clinkers before they are fed into the ball mill of high power consumption, the efficiency of the ball mill was increased because its load was greatly reduced and the specific electric power consumption was significantly saved.

Equipment modification cost : Rs. 20 - 80 MillionReduction of SEC : 2.8%

Savings /Improvement

Heat recovery rate 56.9% to 62.3% (Increased)

Specific

heat

consumption for

cement

(kcal/kg)

20.5 (Reduced)

Crude oil equivalent (kL/y) 2,240 (reduction)

12.8 Energy Efficient Technologies being used in Cement Plants in Japan

Case Study 16: Cement clinker burning process

(a) Adoption of suspension preheater (SP)

Brief

This modification represents installation of a facility to effectively dry and preheat the feed previously blended in the raw material blending section using the flue gas stream from the kiln. This improvement has achieved marked energy saving compared with the conventional wet process.

01) The exhaust gas from the kiln in the dry burning process is about 1050 C. Formerly, the sensible heat of this flue gas was partly recovered by exhaust gas boiler for power generation.

2) The new facility represents a modification which instead directly recovers the sensible heat for drying and preheating the kiln feed.

3) The Suspension preheater is a multistage cyclone and the temperature of 0 0these gas at he outlet of cyclone was 350 -380 c.

Energy Saving

(1) Energy saving effect of the suspension preheater (Production: 4,000 t/D)

(2) Productivity of burning process will be improved.

Capacity of the kiln: one series of 4,000 tons/day facilities (raw materials preparation through burning to finishing)

Investment : Rs 1.2 Billion

(b) Adoption of vertical roller mill for coal crushing

Brief

Formerly, combination of a tube mill and a separator was used mainly for crushing coal. Nowadays, highly efficient vertical roller mills capable of crushing and drying coal, and classifying crushed coal have been com- mercialized. As a result, significant reduction of specific electric power consumption has been achieved.

1) Moist coal is fed either from the top or side to the rotating table of the vertical roller mill.

Savings / Improvement Note

Specific heat recovery kcal/(t-clinker)

3400 to 500 x 10

3Av. 450 x 10

Annual total heat recovery kcal/y

9 594 x 10

Operation: 330 D/y

Crude oil equivalent (kL/y)

264,000

392

A mixture of clinkers and gypsum was crushed by the compression and shear force between the table and three rollers, the latter being hydraulically pressed onto the former.

Energy Saving

Note: * Production : 3,000 tonnes/day at 300 days/year operation

Investment amount : Rs. 250 Million for a 100 tonne / hour grinderReduction in SEC : 19%

References

1. IEA, World Energy Outlook 2007.2. Directory of Energy Conservation Technology in Japan, prepared by

New Energy & Industrial Technology Development Organization, The Energy Conservation Centre, Japan.

3. Investors Manual for Energy Efficiency, EMC, CII & IREDA..4. Bureau of Energy Efficiency. 5. NCCBM (National Council for Cement & Building Materials).6. Portland Cement Association : Innovations in Portland Cement; Shokil

IL, PCA.7. Energy Management Policy-Guidelines for Energy Intensive Industry in

India, Bureau of Energy Efficiency. www.bee-india.com/aboutbee/Action %20 Plan/ 05. tal, html.

8. Energy Efficiency Improvement opportunities for Cement making : An Energy Star Guide for Energy & Plant Managers. Lawrence Berkeley National Laboratory; Ernst Worrell & Christina Galitsky.

9. Assessment of Energy use & Energy Saving Potential in Selected Industrial Sectors in India (Ernest Orland Deptt. Of Environmental Energy Technologies Division; by Jayant Sathaye, Lynn Price, Stephane delaPue can & David Fridley.

10. Energy Efficiency Programmes & Policies in the Industrial Sector in Industrialised Countries, Berkelay, LBNL.

11. Indo-German Energy Efficiency & Environment Project (IGEEP); India.com/aboutsee/implementation/designated/

12. Statistical Pocket Book, India, 45th Edition, 2006-07, Central Statistical Organisation; www.mospi.gov.in.

13. Website : www.ibef.org/artdisprirew.aspx art14. Handbook of Energy Conservation by H.M.Robert & J.H. Collins.

Before improvement After improvement Savings / Improvement

Production capacity(t/hr)

107

160

1.5

times (increase)

Specific electric

power

consumption (kWh/t)

36

29

7

(19% reduction)

Electric power consumption* (MWh/y)

32,400 26,100 6,300 (reduction)

Crude oil equivalent (kl/y) 1,531 (reduction)

393392

13.1 Introduction

India has been known as the original home of sugar and sugarcane. Indian mythology supports the above fact as it contains legends showing the origin of sugarcane. India is the second largest producer of sugarcane next to Brazil.

Apart from sugar, the sugar industry produces certain by-products, which can be used for production of other industrial products. The most important by-product is molasses, which is utilized for production of chemicals and alcohol. In addition, the other important by product is bagasse. It is mainly utilised as a captive fuel in the boilers but it is also used as a raw material in the paper industry.

13.1.2 Number of Sugar Factories

There were 608 installed sugar factories in the country as on 31.12.2007. The sector-wise breakup is as follows:

Table 13.1

* This Includes closed sugar factories also Source: Department of Food & Public Distribution

13.1.3 Production of Sugar

During the sugar season 2007-2008, production of sugar is estimated at about 270 lakh tonnes as against the production of 280 lakh tonnes during the previous season 2006-2007.

Table 13.2: Production of Sugar

(Lakh Tonnes)

Source: Department of Food & Public Distribution

13.2 Energy Profile

The energy requirements in a sugar mill are in the form of steam for process heating/turbo drives and electricity for running various drives. The sugar industry has the unique advantage of utilizing a captive fuel-bagasse, to meet its energy requirements. However, depending upon various factors like fibre content in the cane, quantity of juice, type of clarification process and evaporation effects, type of prime movers (steam driven or electric driven) etc., some sugar mills produce a

1997-98

1998-99

1999-00

2000-01

2001-02

2002-03

2003-04

2004-05

2005-06

2006-2007 (Provisional)

128.44 154.52 181.93 185.10 184.98 201.32 139.58 130.00 193.21 280.00

Sector Number of factories

Cooperative

Private

Public

TOTAL

317

229

62

608 *

Sugar

Chapter 13

395394

profitability to the plant as well as significant reduction in GHG emission.These plants, however, are very few in number.

The Indian sugar industry offers good potential for energy saving. The estimated energy saving potential in the Indian sugar industry is about 20%. This offers potential of about 650 MW of electrical energy.

13.3 Manufacturing process

The sugar manufacturing process normally comprises of juice extraction, juice clarification, evaporation, crystallization, centrifuging, drying, and packing. Steam generation using bagasse as the fuel and electricity generation, mostly through backpressure turbines forms an important part of any sugar factory.

13.3.1 Juice Extraction

The juice extraction plant consists of cane handling, cane preparation and milling sections.

a) Cane handling

Cane is brought mainly by trucks, trollies and bullock carts to the mill. The load is first weighed on a weighing bridge. The sugarcane is mechanically unloaded by a grab type attachment. A truck tippler is also sometimes provided to unload cane, facilitating loading of the sugar cane on to the cane carrier.

b) Cane Preparation

The sugarcane after delivery to the cane carrier is levelled in the leveler before it is fed to the cutter. The cutter shreds the cane to smaller sizes and prepares it for the fibrisor where the cane is converted to a pulp-like mass.

c) Milling

The prepared cane is passed through a milling tandem composed of four to six three-roller mills. The juice is extracted from the cane by squeezing under high pressure in these rollers. Extraction is maximised by leaching the disintegrated exposed cane with weak juice and make-up water in a counter current system. In the sugar industry, this leaching system is called "imbibition".

Mixed juice, which is a mixture of juice extracted normally from the first and second stage milling is fed to the next production stage. The fibrous matter or bagasse', which is left after milling, is used as a fuel for steam generation.

Sugar

13.3.2 Juice clarification

The purification of juice involves (a) juice heating (b) sulphitation (c) clarification and (d) filtration.The mixed juice from the mills is heated in raw juice heater(s). The common process employed in most of the mills in India is Double Sulphitation process. The heated juice is treated with chemicals like milk of lime and sulphur dioxide gas in a juice sulphiter. Various dissolved impurities in the mixed juice are precipitated out. The impurities precipitated are separated to obtain clear sparkle juice in clarifiers. Muddy juice, which settles at the bottom, is filtered in vacuum filters and the filtrate is recycled back to the system. The retention time in the clarifiers is

small quantity of surplus bagasse while others are deficient by a small quantity. These mills, therefore, have to depend in a very limited way on external fuels like fuel oil, LSH, coal etc to supplement their energy requirements. Likewise, some sugar mills during the season can produce a little surplus power while others would be deficient in power by a small margin and hence the dependence on grid power is minimal.

Energy consumption in sugar plants depends on various factors such as its capacity, steam generation parameters, vintage, equipment used etc. Analysis of the energy consumption pattern in the sugar mills reveals that there exists significant scope for improving the energy efficiency in the Indian Sugar Industry. The major reason for the high energy consumption in the industry is the presence of large number of old, small capacity sugar mills which have not invested much over the years in modernizing or upgrading various process equipment. Apart from improving the end use efficiency in the plants, the other most promising energy conservation measure for the industry is to set up high-pressure cogeneration systems. This not only has the potential of opening up additional revenue streams for the sugar plants by way of sale of electricity, it can effectively contribute in reducing the ever widening gap between demand and supply of electricity in various power deficit regions in the country.

13.2.1 Energy consumption in Sugar Industry

Table 13.3

Source: CII-IREDA

The energy consumption in Indian sugar mills range from 0.7 to 0.87 GJ/ tonne of cane against a world average of 0.5 to 0.6 GJ/Tonne of cane crushed.

13.2.2 Energy efficiency in sugar industry

Energy efficiency in sugar industry offers the following benefits:

• In plants having cogeneration facility and where the state utility is able to purchase additional power generated from sugar plants, any improvement in energy efficiency levels of the plant results in increased export to the grid. This reduces the equivalent reduction in power generation from fossil fuel based power plants. This has a significant reduction in carbon emissions.

• In plants having cogeneration facility, but the state utility is not ready to purchase power, improvement in energy efficiency in the plant results in saving in bagasse. This either could be exported to other sugar plants, having cogeneration facility with state utility ready to purchase power, or can be sold to paper plants.

• In plants, which do not have cogeneration facility, energy efficiency directly results in reduced power demand from the state utility. This results in higher

Specific Electrical Energy consumption 30 units/tonne of cane with electric motors & DC Drives

24 units / tonne of cane with diffusers

Specific Thermal Energy steam consumption 38% on cane

397396

Filter cake: When cane juice is clarified and filtered, the resulting cake is known as filter mud or filter cake. It contains most of the colloidal matter precipitated during clarification and has around 63% organic matter. This cake is of great manurial value and is mostly taken by the growers in their own transport after delivering cane to the factory, for use in the fields.

13.4.1 Co- Gen in Sugar Mills

The sugar industry by its inherent nature can generate surplus energy in contrast to the other industries, which are only consumers of energy. With liberalization and increased competition, the generation and selling of excess power to the electricity boards, offers an excellent source of revenue generation to the sugar plants. This is referred to as commercial cogeneration and has been only marginally tapped in our country.

The sugar plants have been adopting co-generation right from the beginning. However, the co-generation has been restricted to generating power and steam only to meet the operational requirements of the plant. Only in the recent years, with the increasing power demand and shortage, commercial cogeneration has been found to be attractive, both from the state utility point of view as well as the sugar plant point of view.

The sugar plant derives additional revenue by selling power to the grid, while the state is able to marginally reduce the 'demand-supply' gap, with reduced investments.

13.5 Technologies & Measures for Energy Efficiency Improvements

Various technologies for energy efficiency improvement are discussed briefly. Some of these technologies are already in use in India while many are in the development phase or not yet commercialized in India. Besides these technologies, one very important step, Indian sugar mills can adopt is to produce smaller sized sugar instead of bolder sugar grains. Simply because of the bolder grain size, 2 to 3% more energy is consumed by the industry.

13.5.1 Improved reliability, economics of steam and power generating systems with film forming polyamines

Technology Description

Corrosion and scaling in boilers and turbines continue to pose problems in maximizing steam and power generation at a minimum cost. The corrosion products (iron and copper oxides) coming with the condensate cause heat insulating deposits in boilers resulting in failures, loss of efficiency, frequent cleaning and increased cost of operations. Traditionally, multiple chemicals like phosphates hydrazine or sulfite have been used to reduce the corrosion and scaling but due to its major drawbacks a " film barrier approach" has been gaining increasing acceptance. It utilizes the film forming properties of aliphatic amines on divalent wet metal surfaces. Organic formulations containing film-forming amines, combination of neutralizing amines, dispersants and complexing agents provide much superior protection to the metal surfaces in boilers and turbines against corrosion scaling and carryover. The selection of the types of amines to be used, is determined by the properties such as vapor/liquid distribution ratio, dissociation constant, basicity,

about 2-3 hours and this invariably results in an appreciable temperature drop. 0Hence the juice is again heated to obtain a temperature of about 105 C.

13.3.3 Evaporation

The juice is concentrated from 15 Brix to around 60 Brix in a multiple-effect evaporator. The vapours are bled from evaporators for juice heating in various heat exchangers and for boiling of massecuite in vacuum pans. This is the major steam consuming section of plant.

13.3.4 Crystallisation

Crystallisation is an important unit operation, which in sugar industry is known as Pan boiling. Major part of the crystallization process is done in most of the sugar plants in batch type vacuum pans. A mixture of the molten liquid and crystals, known as "massecuite" is then transferred to crystallizers where the process is completed by cooling the mass under stirred condition.

13.3.5 Centrifuging

The massecuite from the vacuum pans is sent to the centrifuges, where the sugar crystals are separated from molasses. These centrifugal machines can be batch type or continuous type. There are separate centrifugal machines for ̀ A' type, ̀ B' type and `C' type massecuites. The molasses separated out from this section is a useful byproduct, which is an excellent raw material for distilleries.

13.3.6 Drying, grading and packing

The moist crystals obtained from centrifugal machines normally contain about 15-20% surface moisture. They are dried in traditional dryers, graded according to crystal sizes and then packed in bags.

13.4 By-products

The main by-products from any sugar industry are: (i) bagasse (ii) molasses and (iii) filter cake.

Bagasse: Bagasse is an important by-product of sugar. It is rich in cellulose fibre and can be used as a major substitute raw material in the paper and pulp industry, replacing wood and bamboo thus reducing deforestation. Costly imports of pulp and waste paper can be avoided thus conserving the outflow of foreign exchange. Bagasse has also been suggested as a base material for cattle feed after mixing with molasses in varying proportions. The other important product, which can be manufactured from bagasse, is furfural, which is a very versatile chemical with good potential for commercial usage. Presently, almost all the sugar mills utilize this bagasse as an in-house fuel in boilers for steam generation. Number of mills are now planning to utilise the bagasse efficiently in high-pressure boilers for co generating electricity for export to the grid/neighboring units.

Molasses: Molasses, the other important by-product, is a storehouse of organic chemicals. Industrial alcohol is produced from molasses, which in turn can be used to manufacture chemicals like ethyl benzene, lactic acid, tartaric acid, citric acid, diethyl phthalate, etc. Industrial alcohol can be used as a fuel extender as a substitute to the scarce petroleum products.

399398

quality sugar and final molasses. Molasses is a by-product in the process and can be used as raw material for alcohol industries.

Advantages

• In non-sulphitation plants, suphitation processing equipment is eliminatedfrom the process.

13.5.4 Sugar-cane waste conversion into char

Technology Description

The Appropriate Rural Technology Institute (ARTI), India, at pune has developed a charring process for converting sugar-cane trash into high-value char. Dried leaves of sugar cane, or sugar-cane trash, resist biodegradation and cannot be used either as cattle fodder or as a raw material for making compost. The innovative process is especially suitable for handling large amounts of loose biomass at high speeds and on a continuous basis. Char obtained by this process can be converted into briquettes easily by a variety of well-established briquetting methods. The eco-friendly oven-and-retort type kiln from ARTI is constructed using bricks and mud. The oven is loaded with a retort (1 kg capacity) filled with sugar-cane trash and a fire is lit below the oven using some of the trash itself as fuel. As the retort heats, the trash inside is converted to char and the pyrolysis gas escapes from a hole in the lid of the retort. A cast-iron grate separates the firebox of the chulha and the retort inside the oven. The retort is loaded upside down in the oven so that the pyrolysis gas passes into the firebox and burns, thereby generating additional heat for charring. Moreover, as the pyrolysis gas is used in the kiln itself, venting or flaring is prevented.

Advantages

• The kiln has a conversion efficiency of 30 per cent and operates as acontinuous-batch process.

rd13.5.5 Quintuple 3 effect vapour for sugar melting

Technology Description

In a multiple effect evaporator, vapour bleeding in the later bodies will bring steam economy. But extensive use of this vapour is presently limited to first two bodies due to low temperature of vapours and high scaling patterns in later bodies.

With the installation of condensate flashing system, vapour generation in individual bodies is being augmented by flash vapor in condensate and hence requiring less evaporation. This is leading to more vapours to condenser, as waste. To avoid this, extensive use of vapour of the third body in a quintuple effect evaporator is planned. With increase in pressure of exhaust steam used at first body of evaporator, the pressure conditions of individual bodies changed to higher side matching with the pressures of quadruple effect.

Navbharat Ventures has initiated a project replacing vapour of the second body being used at pan floor and SJ1 heating with vapour of the third body. There is no financial requirement as the same vapour line is used to draw vapour from the third body of quintuple effect evaporator to utility points. Steam saving achieved through extensive use of vapour from third body by converting evaporator system in to

etc. The product has been applied in sugar mills in India for more than five years.

Advantages

• Complete protection against corrosion and scaling.• Clean and scale free surface.• No cleaning of boilers/turbines required for years.• Simplified dosing and monitoring.• Flexibility in operation, as film stable over a pH range of 4 to 11. • Cost saving due to improved heat transfer and reduced blow downs.

13.5.2 Direct production of white sugar in a cane sugar mill

Technology Description

An economical process is disclosed for the direct production of white sugar from clarified juice. Juice from a cane sugar mill, or sugar beet juice, is first contacted with hydrogen peroxide, before passing through granular activated carbon. The juice is then passed through cationic and anionic resins to remove inorganic compounds, colorants, and other impurities. Then the juice may be concentrated and sugar crystallized. White sugar is produced directly, without the need for an intermediate raw sugar crystallization.

Advantages

• The process does not require membrane separation and involves adsorption ofcolour and other impurities using granular activated carbon and ion exchangeresins.

• Chemical regeneration of the carbon is utilized, which enhances theattractiveness of the process.

13.5.3 Mini Sugar Plant (Khandsari plants)

Technology Description

The sugarcane is fed to the cane carrier provided with Cutters. Sugarcane is chopped into pieces and conveyed to the sugarcane mill. Juice is extracted by crushing unit, screened and collected in raw juice tank and pumped into sulphitation towers. Lime and compressed sulphur-di-oxide gas is mixed with juice. After sulphitation, juice is discharged into cracking bels for single boiling where non-sugars become precipitated from the cracking bel. Juice is pumped into settling tank. The heavy precipitated mud and other impurities settle down at the bottom and clear juice is discharged from the valves of the settling tanks and flows by gravity to boiling bels. The muddy juice from the bottom of the settling tanks is discharged in mud tank and is forced into filter press by means of a mud pump. Filtered juice also goes to the juice boiling bels and mud cake is retained in the press and removed when the press is opened. Clear juice from settling tank and filter press is boiled in open pan juice boiling bels and concentrated. The syrup thus formed is sent manually to crystallizers. Proper crystallization takes place in 48 to 72 hours. After washing, sugar is taken out of centrifugal machine and dried. First quality sugar is dried, graded and bagged. Molasses, which come out of centrifugal machine, is reboiled in Molasses Boiling Bels and sent to crystallizers. The process of crystallization, centrifuging, drying and bagging is repeated to obtain second

401400

more than 64 sugar factories all over India. The system consists of Sulphur Melter, Variable Flow Sulphur Pump, Sulphur Furnace with Checkered Refractory Bricks and refractory lining. SO cooler and instrumentation and control system for control 2

of Sulphur feed, combustion air feed etc. The Molten Sulphur flows from top of the furnace downward forming a thin film on the refractory bricks. The film burns efficiently in contact with air to produce SO . SO formation is negligible. 2 3

Depending on the temperature of the furnace, 6-9% SO can be obtained in the exit 2

gases. Operation of the burner is controlled in accordance with process demands i.e SO quantity and quality, sulphur feed rate etc. through use of instrumentation and 2

control system etc .

Advantages

• Extremely steady burning, with capacity variation 70- 300 kg/hr, • Zero sublimation and minimal SO generation, 3

• Optimum sulphur consumption,• Burning rate variation without any change in concentration, • Compatible to automation for juice sulphitation & pH control, • Maintenance free, long life and zero pollution

13.5.8 Bagasse Drier

Technology Description

This is a novel concept of drying bagasse as well as controlling the air pollution. Bagasse Drier is a unique device wherein the hot flue gases are mixed with the wet bagasse from mills. This wet bagasse gets dried up and accumulates all the ash and unburnt carbon with it. This dried bagasse with all the unburnt and ash is fed into the boiler. Thus it acts in two ways. One it dries the wet bagasse there by increasing the system efficiency and saving bagasse. Second, it acts as pollution control device and reduces the SPM of the flue gas. DSCL sugar, Rupapur implemented this technology in the year 2005-2006.

Advantages

• Improved efficiency with better pollution control.

13.5.9 Planetary Gearbox for crystalliser

Technology Description

The mill drive and transmission of its power to mills is an important area of the sugar factory in respect of investment and maintenance cost and energy saving. The conventional mill drive of the present day consists of either DC motor or steam turbines. These drives are operated at about 1000/5000 rpm whereas the power developed by the prime movers is required to be transmitted to the mills at less than 5 rpm. Therefore, a set of high speed and slow motor gear trains is used to achieve the eventual operating speed and the power requirement at the mill. These drives are not only cumbersome occupying huge space but also needs high maintenance and operating cost. The sugar industry has been in search of an efficient and compact alternative to the above inefficient system. Planetary gearbox is an energy efficient, cost effective compact alternative to the conventional drive comprising of gear trains and also hydraulic drive. EID Parry has successfully replaced the existing worm wheel reduction system with the planetary gearbox arrangement for all

quintuple from quadruple is upto 3.5%.

Advantages

• Reduction in steam consumption

13.5.6 Condensate flashing system

Technology Description

Cane contains about 70% of water. This water is extracted along with juice in milling by adding some more water to the cane bagasse, which is called imbibition.

oMixed juice is required to be heated up to 102 C to stall microbiological action on it and to increase the rate of reaction with chemicals (lime and SO gas) added. When 2

concentrated by separating water content in multiple effect evaporation, the vapor condensate takes away heat utilized for heating, often into drain. As was the case of reducing pressure in bodies of multiple effect evaporators in sequence enabling use of vapor for boiling in the subsequent bodies, it is proper to use flash heat in hotter vapor condensates, in subsequent bodies by circulating the condensate sequentially. SEDL (Spray Engineering Devices Ltd.) has improvised the design of the flash vessel for heat recovery from condensate of evaporator, pans and surface contact heaters.

Haidergarh Chini Mills, Barabanki (UP), with help of SEDL has installed a Condensate Cigar along with Plate Heat Exchanger (PHE) at the evaporator station to utilize the waste heat of excess condensate by using flash vapour. Further, PHE facilitated to recover extra heat going along with exhaust condensate to boiler feed water tank. This has stopped the usages steam, which was required for super heating the wash water (up to 115º C) during centrifugal operation.

Advantages

• It reduces the steam consumption in the boiling house by 2.0- 3.0% on Cane depending on the operating conditions of the Boiling House.

• It improves the water management of the Plant. • Space requirement is less due to its compact size and alignment. • The sparge tube entry for condensate helps in proper diffusing of condensate

and hence improves the efficiency for flashing.• Easy to maintain, trouble free, reliable and long life due to stainless steel

construction.

13.5.7 Film Type Sulphur Burner

Technology Description

Sugar juice clarification (purification) process requires sulphur dioxide as a clarification and bleaching agent. It is produced from expensive (imported) sulphur in the conventional tray type batch burners, in Indian sugar factories, which are inefficient, resulting in high processing cost, poor clarification and poor sugar quality. The new "film type sulphur burner" which was tried at Upper Doab Sugar Mills, Shamli in collaboration with M/s. Digital Utilities (India) Pvt. Ltd., New Delhi, produces SO with consistent quality, high efficiency, low consumption and 2

well regulated operation made possible by the new 'film burning' concept and requisite automation. The film type sulphur burner technology has been adopted in

403402

13.5.11 Wet Cell Gasification

Technology Description

Bagasse has traditionally been burned in boilers to help fuel the operations for sugar mills. The problem with burn boilers, particularly older burn boilers is their outputs, not only of useful process heat, but pollution. The burn boilers also require dry feedstock, as very wet feedstock will choke the boiler. Slag and residue forming on boiler tubes and the system can also pose a challenge for consistent operations. The wet cell gasification technology is generally far cleaner than burning or burn boilers. The EWC (Ecology Wet Cell) gasification unit is a two-stage updraft gasifier. In the first stage, the biomass is gasified in a starved oxygen environment. In the second stage, the producer gas is consumed in a powerful double vortex combustor producing 100,000,000 (one hundred million) Btu per hour of heat at

oapproximately 1010 C. The temperature has been successfully varied for particular oapplications to as high as consistent 1204 C. Where there is a large amount of waste

or biomass by products and agricultural residue this robust gasification to heat system can provide a very useful solution. This gasification unit can also handle human and animal waste mixed in with biomass, a very fibrous materials that cause real problems with other feed systems.

Advantages

• Produces large volume of heat effectively and reliably for various applications• Running on a combination of biomass sources.

13.5.12 Mechanical Vapour Compression (MVR) technology to recover low-pressure waste steam

Technology Description

Thermal separation processes such, as evaporation and distillation are energy intensive. The need for reducing energy costs has led to multi-effect plants, then to thermal vapour compression and finally to the use of mechanical vapour compression systems. In mechanical vapour compression, positive displacement compressions or multi-stage centrifugal compressors are generally used to raise the pressure and temperature of the generated vapours. Since mechanical compressors do not require any motive steam, all vapours can be compressed to elevated pressure and temperature, eliminating the need for a subsequent recovery system. The energy supplied to the compressor constitutes the additional energy input to vapours. After the compression of the vapour and its subsequent condensation through transfer of heat to process fluid, the hot condensate leaves the system, which can be used as feed water/liquid for boilers. The technology was developed in the year 2005.

Advantages

• Low specific energy consumption.• High performance co-efficient.• Gentle evaporation of the product due to low temperature differences.• Reduced load on cooling towers. • Simple process for operation and maintenance.

Taking the ratio of cost of steam-generation of the equivalent cost of electrical

crystallizers under its energy saving schemes for the year 2005-2006.

Advantages

• Improved efficiency resulting in energy savings

13.5.10 Advanced bagasse based cogeneration

Technology Description

Cogeneration is broadly defined as the coincident generation of useful thermal energy and electrical power from the same input fuel. Any process plant requiring steam for process, the pressure of steam required for most of the process applications being low, holds very good potential for cogeneration of power. Sugar plants are particularly interesting applications for cogeneration, since bagasse, one of the by-product from the mill, is available almost at no cost as feed stock to fuel the steam generators of the cogeneration plant. The sugar manufacturing process requires a large quantum of thermal energy in the form of steam and also the bulk of the steam required for the processing is needed at low pressure i.e. in the range of 2.0 to 2.5 bar (atm). However, to date, sugar plants had limited power and heat generation to meet only their own in-house demands, which is called as an incidental cogeneration, and hence their existing energy potentials had not been fully exploited. The advanced cogeneration system, aims at significantly improving the overall energy efficiency of the sugar factory, enabling the plant to generate surplus power. The surplus power could be exported to the electricity grid, which can generate additional financial resources for the plant. Energy efficiency and the export of power to the grid is made feasible by the employment of high pressure and high temperature steam cycles and by the utilization of the surplus bagasse to produce more steam and hence more electricity. Thermodynamically, energy recovery from the Rankine cycle is more dependent on the steam inlet temperature than the pressure and the higher the inlet steam temperature; higher will be the cycle efficiency. However, the practically attainable limits of temperatures are influenced by the metallurgy of the boiler tubing, piping and the turbine components and the complexity of the creep fatigue interaction for the

omaterials at higher temperatures. Temperatures up to 400 C require use of ordinary o ocarbon steel and beyond 400 C, low-grade alloy steels are employed. Above 500 C,

the requirements with regard to the material selection are stringent and expensive. oAbove 550 C, the requirements are very stringent and prohibitively expensive. It is

extremely important that the selection of temperature is done keeping in mind the nature of industry, and the experience gained in that industry. The sugar factories

oemploy cogeneration system of 480 C and 65 bar (atm). With the technological advancement, some sugar plants in India implemented the advanced cogeneration

osystem of 515 C and 105 bar (atm) pressure for increasing energy efficiency and the financial profitability.

Advantages

• High efficiency of the plant as well as reduced cost of energy (heat and electricity)• Increased power reliability and quality • Increased financial profitability of the plant • Reduced emissions.

405404

energy as 1:3, the MVR gives economic effect of 17/3 =5.66. The capital cost, installation and operation costs are much lower.

13.5.13 Mill Drives (AC/DC)

Technology Description

DC mill drives are used in most sugar plants in India to drive the milling tandem with four to five 500-1000 HP drives. This is in vogue in most of the plants now with conversion of turbo-steam drive to electrical drive with cogeneration of power for export being the order of the day. However, the new development of using AC drive instead of DC drive has the following advantages.

Advantages

• Efficiency of AC motor is higher than DC motor • Low maintenance cost than DC motor • Less harmonics than DC motor • Overall power saving of 3-5% is possible with AC drive for milling tandem in

place of DC drives.

13.5.14 Adoption of Falling Film Evaporator

Technology Description

The steam consumption of sugar factory, mainly depends upon the system available for the concentration of juice. Adoption of falling film evaporator at the evaporator station, offers better steam economy. Falling film evaporator is usually a conventional 1-1 exchanger designed to operate vertically. The liquid solution enters from the top at such a rate that the tubes do not flow full of liquid, but instead, liquid descends downwards along the inner walls of the tubes as a thin film. Vapour evolved from the liquid is carried downwards with the liquid, and leaves from the bottom of the unit. Since a large number of mills are planning to increase their installed capacities, one of the cost effective ways to achieve the dual objective of better steam economy and increase of throughput in the evaporator section would probably be to add a first evaporator as a falling film evaporator. The concentrated juice from this evaporator body, which can be falling film evaporator, can thus be fed to the existing evaporator setups to continue further evaporation.

Advantages

• Reduced steam consumption • High heat transfer rates. • Increased throughput of the evaporator • Minimal internal pressure drop.

13.5.15 Vertical Continuous Vacuum Pan for Massecuite Boiling

Technology Description

After concentration of juice in multiple effect evaporators, the subsequent process to turn the thick juice into crystal form is accomplished in the vacuum pans. The use of batch type vacuum pans in most of the mills results in considerable fluctuations of steam consumption and irregular sugar quality. It results in variation in syrup brix of about 4-4.5 Bx. The batch pan boiling destabilises the continuous process in

other stations and imbalances steam balance of the plant. The use of fully auto-controlled continuous pan has many advantages over the conventional batch pans. It helps in maintaining a steady consumption of vapours thus eliminating the problems associated with fluctuating vapour flows. Accordingly, there will not be any variations in the syrup brix. This ensures the uniform functioning of the evaporator station, and also boiler steam generation. This system automatically manages the steady conditions for development and uniform growth of crystals eliminating the uncertainties of human operational errors.

Advantages

• Reduction in steam consumption eliminates the fluctuations in the vapour demand thus steadiness of operation is achieved.

• Reduction in boiling point elevation avoids heat injury and colour formation.• Maximum exhaustion of mother liquor. • No fines and conglomerates.

13.5.16 Low Pressure Extraction (LPE) System

Technology Description

The conventional methods of juice extraction suffer from drawbacks of high power consumption, high maintenance costs and require skilled operators. The new LPE system is an efficient alternative, which utilizes combination of solid-liquid extraction and conventional milling technology at low hydraulic pressures. Further, it is not dependent on operator's skill. The system uses perforated rollers in modules of 2. A total of 8 modules (16 rollers) were used during the trial runs. Hydraulic pressure of 110 bar is used. Due to perforations in the rollers extracted juice is quickly drained out. Re-absorption of juice is negligible. The system is driven by electric motors and operation is automatically controlled. The system was successfully commissioned in 1999 for commercial use. Commercial plant at a capacity of 5000 TCD commissioned at Shree Renuka Sugars in 2006.

Advantages

• Low capital cost (about 60%) • Low power consumption to the extent of 35%• Extraction comparable to 4-mill system (about 95%) • Low maintenance cost• No special skills required • Very low retention time • No chemical control.

13.5.17 Membrane filtration for Sugar Manufacturing

Technology Description

The conventional method of manufacturing produces sugar with high sulphur content. That is also brown in colour due to which it does not attract many takers in the export market. Membrane filtration is the process for production of sulphur free, refined quality sugar without going through conventional refining. In this process, high temperature tolerant polymeric membrane modules are employed for sugarcane juice clarification for production of high quality sugar. These membrane modules are capable of withstanding continuous exposure to hot juice without any

407406

Case Study 2: Energy conservation projects at a major unit at Villupuram

1. Replacement of Low-pressure cogeneration system with High-pressure cogeneration system:

Brief

The cogeneration set up had three low-pressure boilers providing steam to the process and turbine generators. Historically the factory has not exported any power to the grid. It was decided to install high-pressure cogeneration system. The configuration of the system is as follows

The plant was commissioned during June 2005. After captive consumption the surplus power has been fed to the State grid.

Energy Savings

2. Replacement of Eddy current drive with Variable frequency drive for Cane carrier & Rake carrier:

Brief

The speed control of the cane carrier and the rake carrier were accomplished by eddy current drives. The eddy current drives were replaced with energy efficient variable frequency drives.

Energy Savings

3. Replacement of slat type bagasse conveyor with belt conveyor:

Brief

A 45 kW slat conveyor was being used to convey bagasse from the mills to the cogeneration power plant material handling system. A 15 kW belt conveyor replaced this slot type conveyor

Boilers Turbines

1 x 120 TPH, 87 kg/cm2 1 x 22 MW

Surplus power exported to grid 15 MWh

Power exported to State grid for the year 2005-06 40.1 Million kWh

Revenue from power export /for the year 2005-06 in Million Rs 125.3

Actual investment in Million Rs 80

Payback Period 8 months

Energy consumption /day with Eddy current drive 2160 kWh

Energy consumption/day with VFD's 1680 kWh

Energy savings/day 480 kWh

Annual Energy savings 86400 kWh

Excess revenue generated Rs in Million 0.26

visible signs of deterioration. The pilot plant was successfully commissioned and operated at Simbholi Sugar mills in 2000-2001.

Advantages

Greater Sugar recovery since less sugar loss in molasses Sparkling clear sugar cane juice with purity higher (by 0.9 units), reduced juice colour (by about 50%) Shorter juice boiling times and faster crystal growth rates increase productivity Easy to integrate, install and scale up with limited space requirement Easy to operate with minimum maintenance requirement.

13.6 Case Studies

Case Study 1: Energy Conservation Achievements at a Major Sugar Industry

Brief

During the period 2006-2007, the unit implemented 15 energy conservation projects with an investment of Rs.17.2 Million achieving a saving of Rs. 7.742 Million.

Energy Savings

The major energy conservation projects are presented below: -

Project Description Annual Savings (Rs. Million)

Investment (Rs. Million)

PaybackPeriod(months)

Quintuple 3rd

effect vapour for sugar melting

A new sugar melter for B & C sugar was designed in -house to utilize quintuple 3 rd

effect vapour instead of exhaust steam

1.171 1.082 11

Plate heatexchanger for turbine condensate heating

Installing the plate heat exchanger enabled heating turbine condensate along with DM water make -up from 40 0C to 980C with qui ntuple 3 rd effect vapour avoiding use of LP steam

0.643

0.270

5

Avoiding FFE transfer pump

Juice transfer scheme was modified and resulting head difference was utilized to completely avoid 15 kW juice transfer pump at falling film evaporator

0.1113

Nil

Immediate

Quintuple 1st effect vapour for FBD sugar dryer air heating

It is general practice to use MP steam for heating air in fluidized bed sugar dryer. The project utilized the same heat exchanger with quintuple 1st vapour as heating medium to heat FD air

0.1098

Nil

Immediate

Quintuple 1st effect vapour condensate as superheated wash water

Replaced usage of MP steam heated condensate with Quintuple 1st effect vapour condensate for washing sugar crystals in batch centrifugals

0.072

0.042

7

Clear juice in place of hot condensate

Clear juice is utilized to the possible extent at pans, continuous centrifugals and melter replacing the use of hot process condensate. Thus reduced evaporation load

0.084

0.065

9

Pipe line to utilize soda-boiling vapour

The vapour from soda boiling are being effectively utilized for process heating by mixing them with the vapour of the main stream, instead of venting to atmosphere as a normal practice

0.263

Nil

Immediate

409408

available for different spraying applications. Most of them aim to give a water spray the form of a hollow cone. A good spray nozzle should be of simple design, high capacity and high efficiency. Of the various types of spray nozzles, the conical jet nozzles have been found far superior on all the above parameters. Hence, the recent trend among the new sugar mills is to install the conical jet nozzles, to achieve maximum dispersion of water particles and cooling.

Energy savings

Annual savings : Rs. 0.32 MillionInvestment required : Rs. 0.50 MillionPayback period : 19 months

Case Study 6: Installation of Regenerative Type Continuous Flat Bottom High Speed Centrifugal for A - Massecuite Curing

Brief

In a 4000 TCD sugar mill, the cooling system consisted of a spray pond. There were 5 pumps of 75 HP rating operating continuously, to achieve the desired cooling parameters. The materials of construction of the spray nozzles were Cast Iron (C.I).The maximum cooling that could be achieved with the spray pond was about 34 - 35 °C.

The spray pond system was modified and conical jet nozzles were installed to achieve mist cooling. The material of construction of the conical jet nozzles is PVC, which enables better nozzle configuration achievement. The cooling achieved with the mist cooling system was about 31 - 32 °C (i.e., a sub-cooling of 2 - 4 °C was achieved). This resulted in avoiding the operation of one 75 HP pump completely.

The better cooling water temperatures, maintained steady vacuum conditions in the condensers thus minimising the frequent vacuum breaks, which occurred in the condensers.

After ImprovementBefore Improvement

After ImprovementBefore Improvement

One of the 4000 TCD sugar mills, had DC drives for their flat bottom high speed centrifugal of 1200 kg/h capacity used for A - massecuite separation. These centrifugal had the conventional type of braking system, with no provisions for recovery of energy expended during changeover to low speed or discharging speed

The regenerative type of braking system was installed for the entire flat bottom high speed centrifugal used forA - massecuite curing.O n e o f t h e m o s t i m p o r t a n t characteristics of a regenerative braking system in an electric centrifugal is that, it permits the partial recovery of the energy expended, during the discharge cycle.

Energy Savings

Case Study 3: Install diffusers in lieu of milling tandem

Brief

Installation of milling tandem is practiced conventionally in sugar plants in India. Milling is highly power and labour oriented equipment. The present trend is to adopt diffusion as an alternative to Milling, considering several advantages diffusion offers over milling.

Energy savings

Reduction in power consumption : 2.88 Million units(Considering an average crushing of 500 TCD for an operating season of 180 days) Energy cost saving : Rs. 8.0 Million / season(Considering power export cost of Rs. 2.75 / kWh)

Case Study 4: Utilisation of Exhaust Steam for Sugar Drier and Sugar Melter

Brief

Energy savings

Annual savings : Rs. 0.2 MillionInvestment required : Rs. 0.02 MillionPayback Period : 2 months

Case Study 5: Installation of Conical Jet Nozzles for Mist Cooling System

Brief

The spray pond is one of the most common types of cooling system in a sugar mill. In a spray pond, warm water is broken into a spray by means of nozzles. The evaporation and the contact of the ambient air with the fine drops of water produce the required degree of cooling. There are many types of nozzle configurations

Slat conveyor Energy consumption /day 756 kWh

Belt conveyor Energy consumption/day 360 kWh

Energy savings/day 396 kWh

Annual Energy savings 71280 kWh

Excess revenue generated Rs in Million 0.214 kWh

Before Improvement After Improvement

A new sugar mill initially decided to

adopt milling in tandem diffuser and it was installed by design

The mill was later on opted for the

Before Improvement

In this 2500 TCD sugar mill, medium 2pressure steam at 7.0 kg/cm , generated

2by passing live steam at 42 kg/cm , through a pressure reducing valve (PRV), was being used for sugar drying and melting

After Improvement

Exhaust steam generated by passing live steam through the turbine was available at around 1.2

2kg/cm . The exhaust steam was utilised in place of live steam for sugar melting (blow-up) and sugar drying.

Replacement of live steam with exhaust steam in these two users increased the cogeneration by about35 units, which could be sold to the grid.

411410

Case Study 8: Installation of 30 MW Commercial Co-generation Plant

Brief

Energy savings

Enhancement in power generation : 9 MW to 23 MW. Surplus power generation for exporting to the grid : 14 MW

Annual savings : Rs. 204.13 MillionInvestment required : Rs. 820.6 MillionPayback period : 48 months

Case Study 9: Replacement of Steam Driven Mill Drives with Electric DC Motor

Brief

Before Improvement After Improvement A 5000 TCD sugar mill in Tamilnadu operating for about 200 days in a year had the following equipment:

Boilers 2 numbers of 18 TPH, 12 ATA 2 numbers of 29 TPH, 15 ATA 1 number of 50 TPH, 15 ATA Turbines 1 number 2.5 MW 1 number 2.0 MW 1 number 1.5 MW

Mill drives 6 numbers 750 BHP steam turbines 1 number 900 BHP shredder turbine The plant had an average steam consumption of 52%. The power requirement of the plant during the sugar-season was met by the internal generation and during the non- season from the grid. The plant went in for a commercial co-generation plant.

The old boilers and turbine were replaced with high- pressure boilers and a single high capacity turbine. The new turbine installed was an extraction-cum- condensing turbine. A provision was also made, for exporting (transmitting) the excess power generated, to the state grid. The mill steam turbines, were replaced with DC drives. The details of the new boilers, turbines and the steam distribution are as indicated below:

Boilers 2 numbers of 70 TPH, 67 ATA Multi-fuel fired boilers Turbines 1 number of 30 MW turbo-alternator set (Extraction-cum-condensing type) Mill drives 4 numbers of 900 HP DC motors for mills 2 numbers of 750 HP DC motors for mills 2 numbers of 1100 kW AC motors for fibrizer.

A 5000 TCD sugar mill had six numbers of 750 HP mill turbines and one number of 900 HP shredder turbine. The average s team consumption per mill (average load of 300 kW) was about 7.5 TPH steam @ 15 Ata. The steam driven mill drives had an efficiency of about 35%, in the case of single stage turbine and about 50%, in the case of two-stage turbines.

The plant team decided to replace the steam driven mills with electric DC motors, along with the commissioning of the cogeneration plant. These drives have very high efficiencies of 90%.Benefits of electric DC drives for mill prime movers• Increased drive efficiency• Additional power export to gridThe power saved (850 kW/mill) by the implementation of this project, could be exported to the grid

After ImprovementBefore Improvement

Energy savings

The regenerative braking system recovers about 1.34 kW/100 kg of sugar produced, during the discharge cycle and feeds it back into the system. Hence, the net power consumption of the centrifugal with the regenerative braking system is only 0.66 kW/100 kg of sugar produced.

Case Study 7: Installation of Jet Condenser with External Extraction of Air

Brief

The evaporators and pans are maintained at low pressures, through injection water pumps. These are one of the highest electrical energy consumers in a sugar mill. The multi-jet condenser, which are presently used in the sugar plants, do both the jobs of providing the barometric leg, as well as removing the non-condensables.

Energy savings

Annual savings : Rs. 1.30 MillionInvestment required : Rs. 2.53 MillionPayback period : 24 months

After ImprovementBefore Improvement

One of the sugar mills with an installed capacity of 2500 TCD had the multi-jet condensers for the c r e a t i o n o f v a c u u m a n d condensation of vapours, from the vacuum pans and evaporator. There were 11 injection water pumps of 100 HP rating, catering to the cooling water requirements of these condensers. These pumps were designed to handle an average maximum crushing capacity of 3200 TCD.

The jet condensers with external extraction of air system were installed. There was a significant drop in water consumption in these condensers, in spite of an increase in crushing capacity (average maximum crushing of 4800 TCD). This resulted in reduction in the number of injection water pumps in operation.

The new injection water pumping system includes - 5 nos. of 100 HP pump and 1 no. of 250 HP pump. Thus, there is a net reduction in the installed injection water pumping capacity of about 350 HP (30% reduction). The actual average power consumption also has registered a significant drop of nearly 180 kW, which amounts to an annual energy saving of 5,18,400 units (for 120 days of sugar season).

413412

Case Study 11: Installation of Variable Speed Drive (VSD) for the Weighed Juice Pump

Brief

Energy savings

Annual savings : Rs. 0.24 MillionInvestment required : Rs. 0.25 MillionPayback period : 12 months

Case Study 12: Installation of Thermo-compressor for use of Low Pressure Steam

Brief

Energy savings

Annual savings : Rs. 6.0 MillionInvestment required : Rs. 2.0 MillionPayback period : 4 months

In a 2600 TCD sugar mill, there was a weighed juice pump operating continuously to meet the process requirements.The pump had the following specifications:• Capacity: 27.77 lps• Head: 45 m• Power consumed: 23 kW

The flow from the weighed juice tank was not uniform. Moreover, the pump was designed for handling the maximum cane-crushing rate.

Variable Frequency Drive was installed for the weighed juice pump and resulted in the following benefits:• Consistent and steady flow to the juice heaters• Improved quality of sulphitation, as the juice flow was steady• Reduced power consumption by an average of 11 kW (a reduction of about 30 - 40%).

Before Improvement After Improvement

Before Improvement After Improvement

In a typical 4000 TCD sugar mill in Maharashtra, the turbine exhaust steam at

20.40 kg/cm was continuously vented out. The quantity of the steam vented, amounted to about 6300 kg/h. There were no process users in the sugar mill or the distillery, which could

2utilise this exhaust steam of 0.40 kg/cm . The distillery required 10 TPH of steam at 1.5

2kg/cm . A separate boiler was meeting the steam requirements of the distillery. The sugar mill boiler met any additional requirement of steam. In both the cases, steam was generated

2 2at 8 kg/cm and reduced to 1.5 kg/cm through a pressure-reducing valve.

A thermo-compressor system was installed, for reusing the turbine exhaust steam, in the distillery. The resultant MP steam saved in the distillery, was passed through the power generating turbines, for generation of additional power.

2The resultant 1.5 kg/cm steam obtained by thermo-compression of exhaust steam, was directly used in the distillery. This reduced the passing of high/ medium-pressure steam through the pressure-reducing valve.

Energy savings

Annual savings : Rs. 62.37 MillionInvestment required : Rs. 42.00 MillionPayback period : 9 months

Case Study 10: Installation of an Extensive Vapour Bleeding System at the Evaporators

Brief

Energy savings

Annual savings : Rs. 11.00 MillionInvestment required : Rs. 6.50 MillionPayback period : 8 months

In a typical 2500 TCD sugar mill, the quintuple effect evaporators were in operation. The specific steam consumption with such a system for a 2500 TCD sugar mill is about 45 to 53 % on cane, depending on the crushing rate.

The typical vapour utilisation system in the evaporators comprises of:

• Vapour bleeding from II- or III- effect forheating (from 35 °C to 70 °C) in the raw(or dynamic) juice heaters

• Vapour bleeding from I- effect for heating(from 65 °C to 90 °C) in the first stage of thesulphited juice heater

• Exhaust steam for heating (from 90 °C to105 °C) in the second stage of the sulphitedjuice heater

• Exhaust steam for heating (from 94 °C to105 °C) in the clear juice heaters

• Exhaust steam for heating in the vacuumpans (C pans)

However, maximum steam economy is achieved, if the vapour from the last two effects can be effectively utilised in the process, as the vapour would be otherwise lost. Also, the load on the evaporator condenser will reduce drastically.

The plant upgraded by installation of the extensive vapour utilisation system at the evaporators. The extensive use of vapour bleeding at evaporators was adopted at the design stage itself in this case. This has resulted in improved steam economy.

However, to ensure the efficient and stable operation of such a system, the exhaust steam pressure has to be maintained

2uniformly at an average of 1.2 - 1.4 kg/cm .

In this particular plant, this was being achieved, through an electronic governor control system for the turbo-alternator sets, in closed loop with the exhaust steam pressure. Whenever, the exhaust steam pressure decreases, the control system will send a signal to the alternator, to reduce the speed. This will reduce the power export to the grid and help achieve steady exhaust pressure and vice-versa.

The specific steam consumption achieved (as % cane crushed) is: 41% on cane

Thus, the specific steam consumption (% on cane) is lower by atleast 7%. This means a saving of 3.5% of bagasse percent cane (or 35 kg of bagasse per ton of cane crushed).

Before Improvement After Improvement

415414

Energy Savings

• Reduction (10 - 20%) in steam consumption as mentioned below:

Annual savings : Rs. 19.26 MillionInvestment required : Rs. 100 MillionPayback period : 63 months

References1. Annual Report 2007-08 Ministry of Consumer Affairs, Food & Public

Distribution, GoI.2. The Indian Sugar Industry Sector Road map 2017; KPMG in India 3. CII - IREDA Publication: "Investors Manual on Energy Efficiency".4. Stasticial Abstract 2007- CSO5. LBNL - 62806; World Best Practice Energy Intensity Value for Selected Industrial Sectors, February 2008.6. TERI Energy Directory and Yearbook 20077. LBNL - 57293; Assessment of Energy use and energy savings potential

in selected industrial sector in India, August 2005.8. Japan Energy Conservation Directory9. LBNL - 54828: Emerging Energy Efficient Technologies in Industry

case studies of selected technologies - May 200410. National Energy Map of India: Technology Vision 203011. Report of the working group on Power for 11th Plan (2007-12)12. Report of the working group on R&D for the Energy Sector for the

formulation of the 11th Five Year Plan (2007-12)13. Report of the working group on new and renewable energy for 10th

Five Year Plan (2007-12)14. BP Statistical Review, June 200815. www.indiansugar.com16. www.eeii.org.in17. www.energymanagertraining.com18. www.avantgarde-india.org

Steam consumption (kg/ ton of massecuite)

Identity With batch Vacuum pan With continuous Vacuum pan

A - massecuite

B - massecuite

C - massecuite

Not available

242

354

Not available

229

313

Case Study 13: Installation of Hydraulic Drives for Mill Prime Movers

Brief

Energy savings

The net installed power consumption reduced from 0.895 kW/TCD (for average crushing of 2500 TCD) to 0.509 kW/TCD (for average crushing of 4800 TCD).

In addition, very stable operating conditions (constant crushing) are being achieved, at almost negligible maintenance costs.

Case Study 14: Install nozzle governing system for multi jet condensers

Brief

Energy savings

Annual savings : Rs. 19 Million per yearInvestment required : Rs. 5 MillionPayback period : 3 months

Case Study 15: Installation of Fully Automated Continuous Vacuum Pans for Curing

Brief

Energy savings

A nozzle governing system was introduced for controlling the water flow to the condenser. There was a substantial reduction in power consumption of the injection water pumps. The power consumption of injection with pumps reduced from 1150 units/ton to 450 units/ton.

A 6750 TCD Plant was consuming 1150 kWh of Power at Cooling & Condensing System

Before Improvement After Improvement

One of the sugar mills had the following mill drive configuration: For 6 mill system- 600 BHP rating steam turbine x 3 nos. (2 mills driven by a single steam turbine) For 4 mill system - 600 BHP rating steam turbine x 2 Nos. (2 mills driven by a single steam turbine) This configuration was designed to cater to the initial installed capacity of 2500 TCD.

The plant teams had plans to increase the cane crushing capacity to 4000 TCD. The inherent disadvantages of the steam turbines can be overcome, especially after the proposed increase in cane crushing rate, by the installation of hydraulic drives.

The modified 4-mill system was provided with a hydraulic drive of 600 kW rating.

After ImprovementBefore Improvement

Before Improvement After Improvement

In a 6000 TCD plant,batch vacuum pans were installed for A- massecuite and B- massecuite and continuous vacuum pans for C- massecuite curing.

C o n s e q u e n t t o t h e c a p a c i t y upgradation to 8000 TCD, continuous vacuum pans were installed for A- massecuite, B- massecuite and C- massecuite curing.

417

Notes

14.1 Introduction

India has the fifth largest reserves of Bauxite in the world, the main raw material for making Aluminium. The per capita Aluminium consumption in India is only 1.6 kg as against 8 kgs in China and 30 kgs in developed countries. The World's average per capita consumption of Aluminium is about 10 times of that of India. The demand of Aluminium is expected to grow by about 9 percent per annum from the present consumption levels. India is a net exporter of Alumina and Aluminium metal. Four Aluminium plants in the country i.e., NALCO (National Aluminium Company Ltd.), HINDALCO (Hindustan Aluminium Company Ltd.), MALCO (Madras Aluminium Company Ltd. & BALCO (Bharat Aluminium Company Ltd.) account for the entire production of Aluminium in the country.

14.2 Present Capacity & Growth Potential

The total installed capacity of Aluminium is about 3% of the global capacity. The installed capacity in 2006-07 of Alumina & primary Aluminium was about 3.02 MT & 1.18 MT (Million tonnes) respectively. The production of Aluminium from 2004-05 to 2006-07 is shown in figure 14.1 below :

Fig - 14.1 : Production of Aluminium

(Source : The Energy Data Directory & Yearbook, Teddy, 2007 & individual company websites)

14.3 Aluminium manufacturing process

Primary Aluminium process consists of four stages :

I. Mining of BauxiteII. Refining of Bauxite ore to produce Alumina (Bayer's process)III. Smelting of Alumina to produce Aluminium (Electrolysis process)

Chapter 14

Aluminium Industry

419418

Fig 14.3 : Material balance for production of one tonne of Alumina

(Source : Investors Manual for Energy Efficiency; EMC; CII & IREDA)

14.3.2 Smelting of Alumina to Aluminium (Electrolysis process)

Alumina is the main input for the production of Aluminium through electrolysis process. The Aluminium metal is produced through electrolytic reduction of calcined Alumina, based on the process invented by C.M. Hall of USA and P.L.T. Heroult of France. However, there are two technologies used in smelting process i.e., Pre-baked system & Soderberg system.

The Pre-baked technology uses multiple anodes in each cell, which are pre-baked in a separate facility and attached to rods to suspend the anodes in the cell. New anodes are exchanged for spent anodes, i.e. anodes butts, recycled into new anodes. This technology is more prevalent in industries. The Soderberg technology uses a continuous anode which is delivered to the cell (pot) in the form of paste, which bakes in the cell itself.

In the Electrolysis process, Alumina is dissolved in fused electrolyte bath of cryolite o oat operating temperature ranging from 920 C to 970 C. Under the influence of high

intensity direct current, Alumina gets dissociated to Aluminium and Oxygen ions in the electrolytic cells. Gases evolved are cleaned to recover the valuable fluorides and reduce the concentration of noxious contaminants before discharge to the atmosphere. Molten Aluminium is tapped from the bottom of electrolytic cells and cast into ingots, billets, etc. for conversion to semis. On an average, it takes 15.7 kWh of electricity to produce one kg of Aluminium from Alumina.

Thereafter, Aluminium semis covering flat and non-flat products are produced utilizing the processes of DC casting, continuous casting, extrusion, hot and cold rolling. Generally about two tonnes of Alumina is required to produce one tonne of Aluminium. Material balance for producing one tonne of Aluminium from Alumina is shown in Figure 14.4 :

Bauxite49 %Al 02 3

2247 kg

REDMUD

1963 kg

CaO 39 kgNa Co 74 kg2 3

Water 921 litre

ALUMINA REFININGS90.9 %

EFFICIENT

Alumina1000 kg

• Soderberg system • Pre-baked system

IV. Casting & Rolling

14.3.1 Alumina Refining (Bayer's Process)

Alumina is the basic raw material for production of Aluminium and is obtained from Bauxite, a mineral containing upto 60% in the form of mono/trihydratec. The Bayer process is the most economical route for production of Alumina, used throughout the world. The production of Alumina from Bauxite is carried out through the Bayer route, an extractive hydro- metallurgical process which belongs to the alkaline group of processes.

Alumina production process consists of crushing and grinding of Bauxite with caustic liquor in ball/rod mills. The slurry after desilication is pumped into large tanks/autoclaves/tubes for digestion at 110°C to 300°C depending upon the mineralogy of Bauxite. The digested slurry is diluted and classified in thickeners. The overflow (Aluminate liquor) is pumped for controlled filtration and underflow containing red mud is washed / filtered and disposed to red mud pond. The filtered Aluminate liquor is cooled to 50-85°C in plate heat exchanger/flash tanks and pumped to precipitation tanks with addition of seed hydrate and retained for 30-75 hours with finishing temperature of 40-55°C depending on the type of Alumina to be produced. The precipitated hydrate slurry is classified and the coarser part (under flow) is filtered and washed to obtain the product hydrate and the fine part is recycled as seed hydrate. The hydrate containing 10-20% moisture, is calcined in rotary kilns/stationary calciners at 1000°C -1200°C to obtain calcined Alumina. Generally two tonnes of Bauxite is required to produce one tonne of Alumina.

Figure 14.2 shows the flow diagram of the Bayer Process & Figure 14.3 shows the material balance for the production of one tonne of Alumina.

Fig 14.2 : Bayer's Process for production of Alumina

421420

The technologies adopted both in India & abroad are same but they differ in energy efficiencies as some of the units in India are still using self-baking anodes, (Soderberg technology) instead of multiple pre-baked anodes. 40% of the installed capacity in India is based on Soderberg technology, whereas 60% of it has switched over to the new more efficient pre-baked technology. The Aluminium plants have set a target of 1-2% reduction in SEC in the next 5 yrs. High electrical energy saving potential exists in the smelter section for the production of Aluminium. The major energy consumption in the Aluminium refining process (Bayers's process) are the digestion and calcination stages. About 30% of the total energy consumption is utilized in digestion process, whereas calcination consumes about 32% of the total energy. Typical energy consumption in different stages is given in the Table 14.1 :

Table 14.1: Typical Energy Consumption in Bayer's Process

(Source : Energy Requirements for Aluminium Production )

14.5 Energy Efficiency measures undertaken in Aluminium Plants in India

Most of the plants have implemented a number of energy conservation measures in the past and have specific plans to implement a few in the near future. Major energy conservation measures implemented during the last three years in this sector are given below:

14.5.1 Aluminium Refining

Medium term projects

• Installation of Programmable Logic Controller (PLC) controlled burners in furnaces.

• Installation of Variable Frequency Drives (VFD) for spent liquor pump feeding to evaporator

• Installation of VFD for red mud pond feed pump• Installation of VFD for filtered aluminate liquor pump• Installation of seal pots for condensate recovery in digesters, evaporators,

HP and LP heaters• Installation of VFD for spent liquor pump feeding to Plate Heat Exchanger

(PHE)• Optimizing the operation of filter feed pumping system• Optimizing the operation of the slurry pumps in precipitation area• Optimizing excess O % in kiln by continuous monitoring2

• Avoiding air infiltration in kiln by continuous monitoring• Avoiding air infiltration in kiln flue gas exhaust line

Process

Energy (GJ/t)

% of total Energy Consumption

Preparation 0.37 2.3

Digestion 4.79 29.5 Settling / Washing 0.65 4.0 Precipitation 1.06 6.5 Evaporation 4.3 26.5 Calcination 5.07 31.2

Fig 14.4 : Material balance for production of one tonne of Aluminium

(Source: Investors Manual for Energy Efficiency, EMC, CII & IREDA)

14.4 Energy Consumption in Aluminium Plants

14.4.1 Energy Intensity

Coal, furnace oil and electricity are primary energy inputs for Aluminium production. Coal is primarily used to generate steam, which is used in the process while fuel oil is mainly used in calcination of Alumina and various furnaces in fabrication plants. Electricity is the major energy input in Aluminium production and is considered to be a prime factor in determining economics of Aluminium production. Energy accounts for nearly 40% of Aluminium production costs for metal. Hence, all primary metal producers have installed their own captive power plants to have uninterrupted power supply for their use. Aluminium has a long working life and can be easily recycled. Recycling would require less energy i.e., about 5% of the total energy required to manufacture primary Aluminium from Bauxite.

As compared to the production of other metals, Aluminium industry is most energy intensive consuming energy to the tune of 80 GJ/tonne (including smelting) of metal, whereas Copper and Zinc production consumes 20 GJ/tonne and 15 GJ/tonne of energy respectively.

14.4.2 Specific Energy Consumption

The specific energy consumption in Indian Aluminium plants is quite high. It ranges between 75.6 GJ/t - 83.2 GJ/t (including smelting) for primary Aluminium. The specific energy consumption in smelting of Aluminium is 15000 - 16500 kWh per tonne. The operating efficiency in terms of energy consumption is only 40%, which theoretically should be about 5990 kWh per tonne of Aluminium metal.

BothMake-up

43 kg

99 %Alumina

CarbonAnode

ElectrohyticReduction

MoltenAluminium

Gas1340 kg

FluxC 12 etc

Slag(Al=Al 0 )2 3

AlINGOTS1000 kg

Blending

423422

diesel operated only. NALCO has introduced Trench concept of mining with staggered movement of faces following the mineralized thickness enabling economical extraction of ore. Selective extraction of contaminated ore at the bottom layer is another important feature of this method of mining. Each trench is mined in two distinct phases: Mass mining of bauxite up to a depth of 10 m by front end loader and dumper combination and selective mining of the remaining bauxite in contact with the wall in the 2nd phase by hydraulic back hoe shovel and dumper combination.

HSD accounts for over 90% of the power cost of the mine and 7 % of the total mining cost, and the management had initiated lot of action in this area. PCRA had conducted the Energy Audit for the HEMMs deployed at this mine.

Energy Savings:

1. Recycling of hydraulic and transmission oil, contribute an annual saving of Rs 4.2 Million. It was proposed to adopt 'Electrostatic Liquid Cleaner in series with Vaccum Dehydration Machine' with a meager investment of Rs 0.4 Million. Annual consumption at the present production level is 35 kL of Hydraulic Oil and 50 kL of Transmission Oil.

2. Recycling of engine oil : The total annual consumption level is to the tune of 3000 kL. By recycling, Rs 1.4 Million can be saved, in addition to improving upon the engine efficiency.

3. Use of Mineral Water in radiators: An amount of Rs 0.57 Million can be saved annually by replacing the present system of using industrial water in radiators alongwith high value coolants.

4. Installing Load Cell in each Dumper : By installing load cells the percentage productivity of the dumpers when loaded by loaders can be improved and quantified. It has been observed that there has been wide variation at times in the percentage loading into the dumpers. By installing load cells in 14 nos. of 50Tonne dumpers, a total saving of Rs 0.34 Million can be achieved. Investment in installing load cells will be about Rs 1.2 Million and payback period is 3 years.

5. Construction of RCC road in permanent haul roads : This can generate a saving of Rs 1.7 Million due to improvement in engine life, fuel saving, better tyre life etc. Investment is Rs 14 Million.

6. Additive dosing in HSD: A total saving of Rs 0.57 Million can be achieved through improvement in efficiency of diesel operated HEMMs like dumpers, dozers, drills, loaders.

7. Performance improvement in blasting : Less generation of oversize boulders result in better productivity of loading and dumping machineries. This also improves productivity of the crusher due to less jamming, uniform feeding, resulting in better electrical motor life.

Some of the other Energy Conservation Initiatives undertaken by the mine are :

• Variable Frequency Drive in Crusher and conveying system• Semi-Mobile Crusher Conveyor system

As part of their 6.0 Million Tonnes expansion plan NALCO management had approved commissioning of 'Semi-Mobile Crusher Conveyor' system. M/s ThyssenKrupp of Pune will execute the work at a cost of over Rs 1 Billion. This

•pumps

• Utilizing the standby body in evaporator and increasing the steam economy

Long-term projects

• Installation of de-super heaters for better heat transfer and steam saving in Aluminium refining.

• Installation of energy efficient screw compressors.• Installation of liquid vapour hydro cyclone in evaporation feed flash tank

to avoid caustic entrainment to the hotwell water and facilities.• Installation of thermo-compressor to recover flash steam from pure

condensate tank in evaporator section.• Segregation of pick-up and drying zone vacuum in red mud filters• Sweetening the digestion process by adding Gibbsitic Bauxite having

higher solubility in downstream of higher temperature digestion circuit. • Installation of technology upgraded recuperator in place of shell type in

melting furnace.

14.5.2 Aluminium Smelter

Medium term projects:

• Installation of data acquisition system• Installation of thyristor control in coke conveying vibrators in carbon plant• Installation of correct size cooling water supply pump for rectifier cooling• Installation of screw conveyor and avoiding the operation of a centrifugal fan

in Carbon plant.• Installation of variable frequency drive for fire hydrant pump• Installation of variable fluid coupling for scrubber fans• Reducing external bus-bar voltage drop across bypass joints and across rod

to stud joints• Improvement of insulation of sidewalls of the pots to minimize the heat loss

due to convection and radiation

Long term projects

• Conversion of the Soderberg technology to the Pre Baked Cathode Technology in the pots

• Installation of point feeding in the Aluminium pots• Coating of cathode surface of electrolytic cells with Titanium Boride (TINOR)• Replacement of hot tamping mix with cold tamping mix • Installation of variable fluid coupling for scrubber ID fans and avoiding

damper control

14.6 Case Studies of Energy Conversation in Indian Aluminium Plants

Case Study 1 : Energy Conservation in Mining area

Brief

Selection of mining equipment is the thrust area for energy conservation in a mine. The NALCO mine is a highly mechanized mine operated with different types of suitable equipment. All the major HEMM (Heavy Earth Moving Machinery) are

Replacing red mud filter vacuum pumps with new high efficiency vacuum

425424

Fig 14.5 : Installation of thermo-compressor for recovery of flash steam

Energy Savings

Quantity of steam recovered : 3 TPHAnnual Savings : Rs 5.48 MillionInvestment : Rs 3 MillionPayback period : 7 months

Case Study 5 : Installing seal pot system for condensate recovery

Brief

The latest trend is to replace steam traps with seal pots wherever steam consumption is more than 1 tonne per hour. Seal pots were installed for condensate recovery in the following equipment:

a) Digestersb) Evaporatorsc) HP heaters & LP heaters

Energy Savings

Steam saved : 250 Kg/hr.Annual Savings : Rs 0.45 MillionInvestment : Rs 0.75 MillionPayback period : 20 months

Case Study 6 : Optimizing excess O in kiln by continuous monitoring2

Brief

Online oxygen analyser was installed and the % of oxygen level in the flue gas is continuously monitored. The combustion air supply to the kiln is controlled and percentage oxygen of 3% is maintained in the flue gas.

Energy Savings

Increase in combustion efficiency (%) : 2Annual Savings : Rs 2.95 MillionInvestment : Rs 0.7 MillionPayback period : 3 months

Motive Steam2 14-15 kg/cm

Thermo Compressor

Evaporator orLP header

FlashSteam

Steam Plant

3 TPH

PCT

will further reduce HSD consumption of the mine and the total energy bill, since this system will reduce the hauling length of the Dumpers.

Case Study 2 : Improved Energy through slotted anode

Brief

A mixture of computational and physical modelling techniques helps conserve energy by improving slotted anode designs, making aluminium reduction cells more efficient. The project was taken up by engineers in their plant. The reducing of 0.10 volt / pot has the potential of saving 325 kWh / t (at 94% current efficiency) & also enhance production of aluminium. In this system, the voltage saving was done by modifying the anode to 'slotted anode' to reduce bubble resistance. The slots were cut width-wise.

Energy Savings

1. Saving of 0.105 volts / pot led to the energy saving of 341 kWh/t aluminium.2. Total Power saving is 116.62 million kWh per year.3. Increase in potline amperage led to increase in smelter production of 8155

MT/yr.4. GHG reduction by 357 kg CO / MT or 122104 t CO /year @ smelter 2 2

capacity of 342000 MT & emission factor as 1047 gm/kwh based on IAI guidelines.

Annual Saving : Rs. 434 Million (energy saving plus production increase) Investment : In-house design & modification.Payback Period : Immediate

Case Study 3 : Installing variable frequency drive for spent liquor pump feeding to evaporator

Brief

Variable frequency drive (VFD) with feed back control for the spent liquor feed pump to new evaporator was installed. Reduction in power consumption of about 400 units/day was achieved.

Energy Savings

Annual Savings : Rs 0.18 MillionInvestment : Rs 0.45 MillionPayback period : 30 months

Case Study 4: Installing thermo-compressor and recovering flash steam from pure condensate tank in evaporator section

Brief

Thermo compressor was installed to recover the flash steam from the pure condensate tank and the recovered steam is sent to low pressure steam header.

2The motive steam used is about 18-20 TPH at a pressure of 12 kg/cm .The schematic diagram of the modified system is shown in figure 14.5 below

427426

Table 14.2 : World Best Practice "Final Energy Intensity" Values for Aluminum Production (values are per metric tonnes aluminium).

* kgce= kilograms of coal equivalent(Source: World Best Practice Energy Intensity Values for selected Industrial Sectors; LBNL; by Worrel E., Price L., Neelis M., Galitsky C. & Nan Z.)

Table 14.3 : World Best Practice "Primary Energy Intensity" Values for Aluminum Production (values are per metric tonnes aluminium).

Note: Primary energy includes electricity generation, transmission, and distribution losses of 67%.

(Source: World Best Practice Energy Intensity Values for selected Industrial Sectors; LBNL; by Worrel E., Price L., Neelis M., Galitsky C. & Nan Z.)

14.8 World Best Practices for Energy Efficiency in Aluminum Industry

Considerable developments have taken place in the process for production of Alumina, Aluminium and semis in the developed countries. Some of these are given below :

14.8.1 Alumina Plants

• Use of rod mills with classifiers for wet grinding of Bauxite.• Adoption of tube digestion system in order to achieve improved digestion

yield.• Adoption of Alcoa combination process for digestion and extraction of

Trihydrate as well as Monohydrate Alumina.• Adoption of direct filtration technology to separate the red mud directly

downstream the digestion under the same conditions of pressure and temperature.

PrimaryAluminium

SecondaryAluminium

kgce*/t

GJ/t

kgce/t GJ/t

Digesting (fuel)

414

12.1

Calcining Kiln (fuel)

223

6.5

Alumina Production

(Bayer)

Electricity

48

1.4

Fuel 35 1.0 Anode Manufacture (Carbon) Electricity 7 0.21 AluminumSmelting (Electrolysis)

Electricity

1671

49.0

Ingot Casting

Electricity

12

0.35

Total 2411 70.6 85 2.5

PrimaryAluminium

SecondaryAluminium

kgce/t

GJ/t

kgce/t GJ/t

Digesting (fuel)

414

12.1

Calcining Kiln (fuel)

223

6.5

Alumina Production

(Bayer)

Electricity

145

4.3

Fuel 35 1.0 Anode Manufacture (Carbon) Electricity

22

0.64

AluminumSmelting (Electrolysis)

Electricity

5064

148.4

Ingot Casting Electricity

36

1.06

Total 5940 174.0 259 7.6

Case Study 7 : Replacing old Horizontal Stud Soderberg (HSS) cells withmodern point feeder prebake cells

Brief

It was proposed to revamp the entire system by installing modern point feeder pre-bake (PFPB) cells. The proposed system require energy consumption of about 990 million kWh/year to produce 29500 tonnes/year of aluminium.

The specific energy consumption for producing one tonnes of Aluminum during electrolysis would be 14 kWh/kg (Electrical Energy).

Energy Savings

Increase in energy efficiency of retrofit prebake cells :10% GHG emission reduction : 50%Water consumption reduction : 30% Reduction in specific consumption of raw materials - Coal tar pitch, aluminium fluride and petroleum coke.Annual Savings : Rs 84 Million

14.7 Energy Consumption (World's Best Practice)

The specific energy consumption of Aluminium plants in key developed countries ranges between 70.5 GJ/t - 73 GJ/t for primary Aluminium. However, considering the best processes in one of the best plants in the World, the SEC is 70.6 GJ/t of primary Aluminium. The specific energy consumption in smelting of Aluminium is 14000 - 14500 kwh per tonne. This is because of the best energy efficiency measures adopted. The 'World's Best Practice Values' for Aluminum production are given in table 14. 2 & 14.3 below. These values consist of :

(i) Final Energy Intensity Values, i.e. Energy used at the production facility.(ii) Primary Energy Intensity Values, i.e. sum of the energy used at the

production facility plus energy used to produce electricity consumed at the facility.

In this assessment, the energy used for Bauxite extraction is not included because it depends on the ore deposit characteristics. Also, the secondary Aluminium production is based on melting and reshaping scrap Aluminium.

Table 14.2 provides best practice final energy intensity values for the process steps for primary Aluminium production along with the best practice energy intensity value for secondary Aluminium production. Table 14.3 provides primary energy values for these two Aluminium production processes.

429428

Annual saving : (@65Kg. /hr. production rate & 1600 hrs./yr. Operation & holding time of 2 hrs./day)

Investment : Rs 2 Million Payback period : 13months

Case Study 9 : Installation of a small capacity variable pump for keeping hydraulic pressure

Brief

Even when pressure oil was not needed for the pressure-oil system, the main pump of the hydraulic unit was operated in order to compensate leaks. Instead, a small-capacity pump is installed to compensate leaks. The main pump operation requires 11 kW of electric power whereas, the small-capacity pump operation requires only 3.7 kW.

Energy Savings

Energy Savings (kW) : 7.3Annual saving : Rs 0.2 MillionInvestment amount : Rs 0.2 MillionPayback: period : 1 year

Case Study 10 : Variable Voltage Variable Frequency (VVVF) control of pumps and fume blowers, and flow rate reduction of by-pass circuit

Brief

In a rolling schedule, the time ratio between the rolling operation and the set-up operation is 3:2. The conventional method was as follows:

1) Coolant pumps and fume blowers were operated continuously.2) During the set-up, output of the coolant pumps was returned to the

coolant tank through the bypass by switching the 3-way valve. However,power consumption in the set-up time was greater than that in the rolling operation.

The following measures were taken:

1) The numbers of revolutions of the coolant pumps and fume blowers are controlled in accordance with the rolling schedule by introducing the VVVF apparatus.

2) Power consumption by the coolant pumps during the set-up time is reduced by throttling the valve of the bypass circuit to the coolant pumps.

Energy savings

Reduction of power consumption by VVVF control : 2 Million kWh/yearReduction of power consumption by throttling the bypass valve : 1.2 Million kWh/yrAnnual Saving : Rs 2 MillionInvestment : Rs 4 MillionPayback period : 2 years

Rs 1.8 MillionLiquor purification system for removal of carbonates and organic matters.• Improved mechanical agitation system for precipitators.• Adoption of special disc filters for filtration of seed and product hydrate.• Adoption of multistage falling film evaporation systems in place of

conventional single stage system.• Installation of stationary calciners in place of conventional rotary kilns.• Adoption of dry disposal system of red mud.• Automation and computerized process control systems for better

operation of the plants.

14.8.2 Aluminum Smelters

• Improvement in electrolyte bath chemistry to minimize re-oxidation of metal.

• Improvement in Alumina feeding system by adopting point feeding for proper distribution of Alumina in the electrolyte.

• Improvement on magnetic field characteristics through bus-bar network redesign for stable metal pad.

• Increase in the current efficiency by accurate control of process parameters.• Possibility of lowering anode current density by increasing the anode size.• Replacement of monolithic cathode lining with prebaked cathode blocks

for better cell life.

14.8.3 Semis Production

• New processes like CONFORM extrusion and hydro-static extrusion for improved extruded products.

14.9 Energy Efficient Technologies being used in Aluminum Plants in Japan

Case Study 8 : Immersion melting plating furnace

Brief

A conventional furnace indirectly heats the metal in a vessel made of steel from outside through the vessel bottom or side wall. An immersion melting furnace is an energy-saving type furnace which heats the metal directly with a combustion-heating immersion tube. The furnace has a combustion-heating immersion tube integrated with a special gas burner made of ceramic, a temperature sensor, and specially-designed furnace- temperature control device.

Energy Savings

•

Before Improvement

After

Improvement

Saving /

Improvement

Specific energy consumption(kCal/kg)

2500

700

1800

Holding energy consumption (kCal/kg)

62,000 23,000 39,000

431430

Annual saving : Rs 10 MillionInvestment : Rs 28 Million Payback period : 3 years

Case Study 13 : Improving Operation by reduced number of revolutions of circulating fan

Brief

A circulating fan of a soaking pit was constantly operated at 100% of the number of revolutions from the start to the end of the operation. Energy saving is realized by the improvement of operation, where the number of revolutions of the circulating fan is reduced.

Following two points are found by controlling the number of revolutions of the circulating fan:

1) Reducing the number of revolutions of the circulating fan for a few hours after the start of heating does not change the heating time.

2) Reducing the number of revolutions of the circulating fan after the end of soaking gives no effects on material temperature.

Energy saving

From start to 3 hours : 70 kW to 35 kW After end of soaking : 56 kW to 28 kWAnnual saving : Rs 2 MillionInvestment : Rs 2.8 MillionPayback period : 1.5 years

Case Study 14 : Heat loss improvement of energy saving type electric holding furnace

Brief

This is an example of improvement of heat loss at electric holding furnaces used near the casting machine following the melting work of aluminium alloy ingot. Although individual energy consumption is not large, it has a huge effect considering that a number of electric holding furnaces have been already installed.

Energy savings

Annual saving : Rs 0.8 MillionInvestment : Rs 2 MillionPayback period : 2.5 years

Before Improvement

After

Improvement Saving/

Improvement

Electricity

consumption amount (kWh/y)

156,000

42,000

114,000

Crude oil saving amount rate (kL/y)

-

-

28

Case Study 11 : Improvement of thermal efficiency for rapid aluminium melting furnace

Brief

Approximately 30% reduction of unit requirement of energy has been achieved through measures as :

• mixing of molten metal• burner combustion control • controlling the molten metal temperature • controlling furnace pressure• installation of recuperator.

Energy savings

Energy savings

Energy savings (kL/yr.) : 184Annual saving : Rs 16 MillionInvestment : Rs 24 MillionPayback period : 1.5 years

Case Study 12 : Regenerative burner type aluminium melting furnace

Brief

This improvement is to use a highly efficient furnace for melting aluminium. The furnace employs oil or gas fired regenerative type burners and reduces the specific fuel consumption by more than 30 % compared with a conventional melting furnace. Operating condition of furnace is 40 T/charge, 4 charges/day & 300 days/yr.

Energy savings

Conventional iron

melting furnace After improvement

(immersion type holding furnace)

Saving/ Improvement

Energy unitrequirement (kcal/kg)

50

(100%)

22 (44%)

28

Yield (metalloss)( kg/T)

7 (100%)

2

(29%)

5

Conventionalmelting furnace

Regenerative meltingfurnace

Effect

Waste heat recovery

methodRecuperator

Regenerative

substance

(alumina

ball)

Combustion air

temperature

0200

C

on average

0 800 C

on average

0Increase by 600 C

Air ratio 1.2

on average

1.1

on

average

Reduced

Waste heat recovery ratio

15.1

%

68.2

%

Increased by 53.1%

Specific fuelconsumption

682

x

103

kCal/t

478

x

10 3

kCal/t 204

x

10

3 kCal/t

(30%

reduced)Heat efficiency 40.2 % 57.5 % Increased by 17.3%

Reduction in crude oil equivalent

1,058.6 kL/year

-

433432

e) Provision of dry scrubbing system for gas cleaning and recovery of fluorides.

f) Computerisation of baking furnace firing system.

14.10.3 Semis

a) Electromagnetic casting of slabs and billets.

b) Hot top casting of billets with air-slip process.

(ii) Rolling

a) Thin strip casting with cold rolling.

b) Introduction of automatic gauge, flatness and crown control systems.

e) Improved design features for heat treatment furnaces.

(iii) Extrusion

b) Introduction of efficient heat treatment (Air & Water quenching on run-out table).

d) Installation of combined direct/indirect extrusion press.

e) Installation of Confirm extrusion process.

References:

1. 'Technology Evaluation in Aluminum Industry' by Department of Scientific & Industrial Research-2006.

2. Directory of Energy Conservation Technology in Japan, prepared by New Energy & Industrial Technology Development Organization, The Energy Conversation Centre, Japan.

3. Investors Manual for Energy Efficiency, Energy Management Centre, CII & IREDA.

4. Energy Management Policy -Guidelines for Energy Intensive Industry of India, Bureau of Energy Efficiency.

5. Websites : http://www.qal.com.au/ : http://www.mam.gov.tr/

6. The Energy Data Directory & Yearbook, TEDDY, 20077. World Best Practice Energy Intensity Values for Selected Industrial

Sectors (Ernest Orlando Lawrence Berkeley National Laboratory), Environmental Energy Technologies Division; by Ernst Worrell, Lynn Price, Maarten Neelis, Christina Galitsky & Zhon Nan, 2008.

8. A book on Life cycle Assessment of Aluminum - Inventory Data for the Worldwide Primary Aluminum Industry, International Aluminum Institute.

9. Energy Requirements in Relation to Prevention & Re-use of waste streams. Report : Aluminum, Worrell, E. & de Beer J, 2006.

10. A book on Process Heating in the Metals Industry by Flannagam J.M. 11. A book on Energy Requirements for Aluminum Production : Historical

Perspectives, Theoretical Limits & New opportunities by Choate W.T., Green J.A.S.

12. Electrolytic Production of Aluminium, Electrochemistry Encyclopedia, Electrochemical Technology Corpn., Beck T.R., (http:// electrochem.cwru.edu/ed/encycl/art-a01-al-prod.htm)

13. IEA, World Energy Outlook, 2007.

Case Study 15 : Improvement of operation of hot air circulation fan for the Aluminium annealing furnace

Brief

This is an example of remodeling the operation pattern of the hot air circulation fan of an annealing furnace for aluminium coil heat treatment to contribute to energy saving. The coil annealing furnace is a batch type electric furnace. Without replacing the existing motor, a frequency converter has been installed in the control board of the fan motor.

Energy Savings

Annual saving : Rs 1.6 MillionInvestment : Rs 2.5 MillionPayback period : 1.5 years

14.10 Directory of ENCON Measures with expected benefits

14.10.1 Alumina

a) Replacement of existing rotary kilns with stationary calciners.

b) Adoption of tube digestion system for dissolution of predominantly monohydrate Bauxites.

c) Removal of impurities from plant liquor.

d) Adoption of dry disposal of red mud.

e) Use of Variable Speed Drives for major process pumps and large motors in the plant.

f) Provision of mechanical agitation or improved air agitation system in precipitation unit.

g) Modernization of process control system in plants.

14.10.2 Aluminium

a) Improvement in cell design

b) Redesigning of bus bar arrangement.

c) Provision of improved Alumina transportation system.

d) Provision of mechanized and automated cell operations.

Beforeimprovement

Afterimprovement

Saving / Improvement

Production volume

(t/y) 29,568

29,616

Electric power

consumption (kWh/y)

1,502,904

1,284,400

218,504 (reduced)

Electric power

unit

requirement (kWh/t)

50.8

43.4

7.4 (reduced)

Reduction converted

into crude oil (kL/y)

53

48 (increased)

ØChapter - 15 Impact of climate change in India

Section 5Climate Change

437

15.1 Introduction:

A sustainable energy future would mean society's energy needs are met using resources that are available to us over the short, medium & long-term basis. At the same time, it would mean producing and utilizing all these energy resources in a way that minimizes adverse impact on the environment and maximizes economic & social benefits. Creating a sustainable energy future is a significant challenge, because of :

• Surging energy demand driven by population growth and economicdevelopment

• Environmental impact of energy production and consumption, particularlythose associated with Green House Gas (GHG) emissions

• Concern about security of supplies

It is the rapid pace of industrialization during the last 70 years, that has contributed immensely to the surge in energy demand, increased emissions and Global warming leading to climate change.

15.2 Global Warming:

Global warming is the increase in the average measured temperature of the Earth's near-surface air and oceans since the mid-twentieth century. The average global air temperature near the Earth's surface increased by 0.74 ± 0.18°C (1.33 ± 0.32°F) during the last hundred years ending 2005. Climate model projections summarized by the Intergovernmental Panel on Climate Change (IPCC) indicate that average Global surface temperature is likely to rise further by 1.1 to 6.4°C (2.0 to 11.5°F) during the twenty-first century. The climate model further projects that, "most of the observed increase in Globally averaged temperature since the mid-twentieth century is very likely due to the observed increase in anthropogenic (man-made) Green House Gas concentrations" via an enhanced greenhouse effect.

15.3 Green House Gases (GHG) in the atmosphere:

The greenhouse effect is the process by which absorption and emission of infrared radiations by atmospheric gases warm a planet's lower atmosphere and surface. As can be seen from figure -15.1, the monthly CO measurements display small 2

seasonal oscillations in an overall yearly uptrend; each year's maximum is reached during the Northern Hemisphere's late spring and declines during the Northern Hemisphere growing season as plants remove some CO from the atmosphere. 2

Existence of the greenhouse effect as such is not disputed. Naturally occurring greenhouse gases have a mean warming effect of about 33°C (59°F), without which Earth would be uninhabitable. On Earth, the major greenhouse gases are water vapor, which causes about 36-70% of the greenhouse effect (not including clouds), carbon dioxide (CO ), which causes 9-26% methane (CH ), which causes 4-9% and 2 4

ozone, which causes 3-7% green house effect. The concern is how the strength of the greenhouse effect changes when human activity increases the atmospheric concentrations of some greenhouse gases.

Chapter 15

Impact of Climate Change in India

439438

Public transport

3%

Private transport

10%

Home-electricity

12%

Food & drink

5%Holiday flights

6%Clothes and personal

effects

4%

Car manufacture &

delivery

7%

House-buildings and

fumishings

9%

Recreation & leisure

14%

Financial service

3%

Share of public

services

12%

Home-gas, oil and coal

15%

15.3.1 Attributed & expected effects of Green House Gases :

Although it is difficult to connect specific weather events to Global warming, an increase in Global temperatures may in turn cause broader changes, including glaciers retreat, arctic shrinkage and worldwide sea level rise. Changes in the amount and pattern of precipitation may result in flooding and drought. There may also be changes in the frequency and intensity of extreme weather events. Other effects may include changes in agricultural yields, addition of new trade routes, reduced summer stream flows, species extinctions and increases in the range of disease vectors. One study predicts 18 to 35% of a sample of 1,103 animal and plant species would be extinct by 2050, based on future climate projections.

15.3.2 Carbon FootprintThe carbon footprint is a measure of the impact our activities have on the environment and in particular climate change. It relates to the amount of greenhouse gases produced in our day-to-day lives through burning of fossil fuels for electricity generation, heating and transportation etc.

The carbon footprint is a measure of all greenhouse gases we individually produce and has units of tonne (or kg) of carbon dioxide equivalent.

The pie chart below shows the main elements which make up the total of a typical person's carbon footprint in the developed world. A carbon footprint is made up of the sum of two parts, the primary footprint (shown on the right side of the pie chart) and the secondary footprint (shown on the left side of the pie chart).

Fig. 15.2 : Carbon Footprints

Secondary Footprint Primary FootprintSource : www.carbonprint.com

i. The primary footprint is a measure of our direct emissions of CO from the 2

burning of fossil fuels including domestic energy consumption and transportation. We have direct control of these.

ii. The secondary footprint is a measure of the indirect CO emissions from the 2

whole lifecycle of products we use - those associated with their manufacture and eventual breakdown. To put it very simply, the more we buy the more emissions will be caused on our behalf.

Fig 1 : 15.1 Increases in atmospheric carbon dioxide (CO ). since 19602

(Source :http://en.wikipedia.org/wiki/globalwarming)

Human induced anthropogenic green-house gases emissions are from activities like:

- Energy production from fossil fuels- Industrial activities- Transport- Construction- Agriculture- Land use change & deforestration

The Global Warming Potential (GWP) of the 6 GHG gases accounted in terms of their CO equivalent are given in Table - 15.1 2

Table - 15.1

Source : www.unfccc.com

The present atmospheric concentration of CO is about 385 parts per million (ppm) 2

by volume. Future CO levels are expected to rise due to ongoing burning of fossil 2

fuels and land-use change. The rate of rise will depend on uncertain economic, sociological, technological and natural developments, but may be ultimately limited by the availability of fossil fuels. The IPCC special report on 'Emissions Scenarios' gives a wide range of future CO scenarios, ranging from 541 to 970 ppm 2

by the year 2100. Fossil fuel reserves are expected to be sufficient to reach this level and continue emissions past 2100 as well.

Gas GWP Carbon Dioxide (CO2) 1 Methane (CH4) 21 Nitrous Oxide (N2O) 310 Hydro-fluoracarbons (HFC) 11700 Perfluorocarbon (PFC) 9500 Sulphur Hexaflouride (SF6 ) 23900

12131011700950023900

441440

15.4.2 Kyoto Protocol:

rd th The Kyoto Protocol adopted by the 3 Conference Of Parties (COP) on 11 December th1997 in Kyoto (Japan) and entered into force on 16 February 2005, is an international

agreement linked to the UNFCCC. The major feature of the Kyoto Protocol is that it sets binding targets for 37 industrialized countries including the European Union for reducing Green House Gas (GHG) emissions. These amount to an average of five percent against 1990 levels over the five-year period 2008-2012.

The major distinction between the Protocol and the Convention is that, while the Convention encouraged industrialized countries to stabilize GHG emissions, the Protocol commits them to do so. Recognizing that developed countries are principally responsible for the current high levels of GHG emissions in the atmosphere as a result of more than 150 years of industrial activity, the Protocol places a heavier burden on developed nations under the principle of "common but differentiated responsibilities". 183 Parties of the Convention have ratified the Protocol till date.

15.4.3 The Kyoto Mechanisms

Under the Treaty, countries must meet their targets primarily through national measures. However, the Kyoto Protocol offers them an additional means of meeting their targets by way of three market-based mechanisms. The Kyoto mechanisms are:

• Emissions trading - known as "the carbon market"• Clean Development Mechanism (CDM)• Joint implementation

The mechanisms help stimulate green investment and help Parties meet their emission targets in a cost-effective way. The Kyoto Protocol is generally seen as an important first step towards a truly Global emission reduction regime that will stablise GHG emissions and provide the essential architecture for any future international agreement on climate change.

By the end of the first commitment period of the Kyoto Protocol in 2012, a new international framework needs to be negotiated and ratified that can deliver the stringent emission reductions, the intergovernmental Panel on Climate Change (IPCC) has clearly indicated are needed.

15.4.4. Clean Development Mechanism (CDM):

To help countries meet their emission targets and to encourage the private sector and developing countries to contribute to emission reduction efforts, negotiators of the Protocol included three market-based mechanisms - Emission Trading, the Clean Development Mechanism (CDM) and Joint Implementation

The CDM defined in Article 12 of the Kyoto Protocol allows emission-reduction or emission removal projects in developing countries to earn Certified Emission Reduction (CER) credits, each equivalent to one tonne of CO . These CERs can be 2

traded and sold and used by industrialized countries to meet a part of their emission reduction targets under the Kyoto Protocol.

15.4 United Nations Framework Convention on Climate Change (UNFCCC)

The United Nations Framework Convention on Climate Change (UNFCCC) is an international environmental treaty produced at the United Nations Conference on Environment and Development (UNCED), informally known as the 'Earth Summit', held in Rio de Janeiro from 3 to 14 June 1992. The treaty is aimed at stabilizing greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system.

On June 12, 1992, 154 nations signed the UNFCCC, that upon ratification committed signatories' Governments to a voluntary "non-binding aim" to reduce atmospheric concentrations of greenhouse gases with the goal of "preventing dangerous anthropogenic interference with Earth's Climate System." These actions were aimed primarily at industrialized countries, with the intention of stabilizing their emissions of greenhouse gases at 1990 levels by the year 2000.

Since the UNFCCC entered into force, the parties have been meeting annually in Conferences of the Parties (COP) to assess progress in dealing with climate change. The last COP i.e. COP 14, was held from Dec. 01-12, 2008 at Poznan, Poland.

15.4.1 Annexure I, Annexure II Countries & Developing Countries:

Signatories to the UNFCCC are split into three groups:

• Annex I countries (industrialized countries) • Annex II countries (developed countries which pay for costs of

developing countries) • Developing countries (also known as non- Annex I countries)

Annex I countries agree to reduce their emissions (particularly carbon dioxide) to target levels below their 1990 emissions. If they cannot do so, they must buy emission credits or invest in conservation projects. Annex II countries, that have to provide financial resources for the developing countries, are a sub-group of the annex I countries consisting of the OECD members, without those that were with transition economy in 1992.

Developing countries have no immediate restrictions under the UNFCCC. This serves three purposes:

• Avoids restrictions on growth because pollution is strongly linked to industrial growth, and developing economies can potentially grow very fast.

• They cannot sell emissions credits to industrialized nations to permit them to over-pollute.

• Money and technologies are readily available from the developed countries in Annex II.

Developing countries are not expected to implement their commitments under the convention unless developed countries supply enough funding and technology and this has lower priority than economic and social development in dealing with poverty. Developing countries may volunteer to become Annex I countries, when they are sufficiently developed.

The list of Annex I, Annex II & Non - Annex I countries is available on website of UNFCCC. (http://unfccc.int/)

443442

15.4.6 Stakeholders in CDM project:

The various stakeholders in CDM project are:

• The project developer: for project design, implementation and emissionsmonitoring. This includes the industry, CDM consultant andimplementing agency.

• The Host Country's Designated National Authority (DNA): who wouldapprove the project based on national sustainable development objectives. In India, the DNA is Ministry of Environment & Forest (MoEF).

• The Designated Operating Entities (DOE): for Validation against CDMrules and Verification &Certification of actual emissions in terms of tonnes of CO reduction.2

• The Executive Board of UNFCCC: for issuance of Certified EmissionReductions (CERs) certificate.

The total time required from the date of conception of the project to issuance of CERs is normally 90-100 weeks.

15.4.7 Scale of CDM projects :

All the CDM projects in developing countries (non-annexure I countries) can be categorized into:

i. Small Scale Projectsii. Large Scale Projects

Small Scale project are those which are eligible for fast-track procedures (including simplified baselines) provided by the CDM Executive Board and monitoring requirements. The various categories of Small Scale projects are:

•Type I : Renewable Energy Projects with a maximum output capacity upto 15 MW

•Type II : Energy Efficiency improvement projects, which reduce energy consumption on the supply and / or demand side, upto 60 Gwh per year annually

•Type III : Other project activities that both reduce emissions by sources and that directly emit less than 60, 000 tonnes CO equivalent annually.2

The projects which do not fall under Small Scale projects are categorized into large-scale projects.

The number of approved 'Methodologies' for CDM projects by the EB of UNFCCC upto March 2008 are:

• For large-scale projects = 80 • For consolidated projects = 19 • For small-scale projects = 38

15.5 Indian Scenario on Climate Change :

India's per capita CO emissions are very low, at just over one tonne in 2005, 2

compared to 11 tonnes in the OECD countries. They are about half those of the developing countries on an average. However, the emissions are expected to rise by almost 60% by the year 2015. In 2005, India had released about 1.1 Gt of CO , 2

which is 4% of the world total. It is estimated that by 2030, per capita emissions in

The mechanism stimulates sustainable development and emission reductions, while giving industrialized countries some flexibility in how they meet their emission reduction limitation targets. The projects must qualify through a rigorous public registration and issuance process designed to ensure real, measurable and verifiable emission reductions that are additional to what would have occurred without the project. The mechanism is overseen by the CDM Executive Board, answerable ultimately to the countries that have ratified the Kyoto Protocol.

In order to be considered for registration, a project must first be approved by the Designated National Association (DNA). Public funding of CDM project activities must not result in the diversion of official development assistance. Operational since the beginning of 2006, the mechanism has already registered more than 1133 projects and is anticipated to produce CERs amounting to more than 2.7 billion tonnes of CO equivalent in the first commitment period of the Kyoto Protocol, 2

2008-2012.

15.4.5 CDM eligibility:

For a project to be considered for CDM, it should fulfill the following eligibility criteria:

• The project must be in non - annexure 1 countries.• The projects to reduce / eliminate emission than the usual measures taken

to achieve the same objective (e.g. use of biomass / windmill in place of coal to generate electricity).

• Participation in CDM is voluntary• The project contributes to the Sustainable Development of the host country, i.e. the country where the project is being implemented. The

sustainable development indicators are:

• Social well-being.• Economic well-being.• Environmental well-being and • Technological well-being.

• The project results in real, measurable and long term benefits in terms ofclimate change mitigation, i.e. to assist in environment friendlytechnology transfer, generate investment in developing countries and promote sustainable development.

• The emission reduction must be 'Additional' to any reduction that wouldhave occurred without the project .

To satisfy the "Additional" criteria, the project:

• Should have started after the year 2000.• Should not be the only alternative consistent with current laws and

legislations.• Should not be the most lucrative investment option• Is not a 'common practice', i.e. 'Business As Usual' (BAU)

The above additional criteria have an impact on CDM registration.

445444

Table 15.2 : The energy sector CO emissions in the baseline scenario * (Tg CO ) 2 2

* Tg - Terra gms.

(Source : CDM Implementation in India; The National Strategy Studies, MOEF & TERI)

15.5.3 Clean Development Mechanism in India

India has given host-country approval for 969 CDM projects as of July 2008. Renewable energy, including the renewable biomass, accounted for the largest number of projects (533), followed by energy efficiency (303). Very few projects in the forestry (6) and municipal solid waste (18) were included, despite their large potential. The expected investments in these 753 projects (if all go on stream) is about Rs. 1,06,900 crores.

Of the 969 projects, 347 projects have been registered by the Multilateral Executive Board (CDMEB). India accounts for about 32% of the world total of 1133 projects registered with the CDM EB till July 2008, followed by China, 22%, Brazil, 13%, and Mexico, 10% (Source: UNFCCC). About 493 million Certified Emission Reductions (CERs) are expected to be generated until 2012 if all these host-country approved projects in India go on stream. As of July 2008, 173 million CERs had been issued to projects worldwide, of which India accounted for 26.17%, CERs (39.33 million), China, 35.22%, Korea, 15.73% and Brazil, 12.99%.

The type of CDM projects registered in India are given below:

Fig 15.3 : Type of registered CDM projects in India

(Source : Institute of Global Warming Environmental Strategy)

Some cross-cutting challenges in CDM implementation in India are listed below:

• The projects from India are generally small. Of the 347 projects registeredwith the CDM EB till July 2008, more than 60% are small-scale projects (interms of the protocol definition).

• The portfolio is dominated by unilateral projects, i.e. the investors are Indian parties, employ locally available technologies and use domestic financial

resources. While this has provided a significant impetus to local innovation,

1990 2010 2020 Baseline 532 1555 2308 Coal 327 895 1336 Oil 178 553 777 Gas 27 107 198

India are projected to double, but still these will be well below those of the OECD countries.

India signed and ratified the Kyoto Protocol in August, 2002. Since India is exempted from the framework of the treaty, it is expected to gain from the protocol in terms of transfer of technology and related foreign investments. Following the principle of common but differentiated responsibility, India maintains that the major responsibility of curbing emissions rests with the developed countries, which have accumulated emissions over a long period of time. However, the U.S. and other Western nations assert that India and China will account for most of the emissions in the coming decades, owing to their rapid industrialization and economic growth.

15.5.1 The Indian climate-friendly initiatives

The GHG intensity of the Indian economy in the year 2000, in terms of the purchasing power parity, is estimated to be little above 0.4 tonne CO equivalent 2

per 1000 US dollars, which is lower than that of the USA and the global average. The Indian Government has targeted around 8-9% GDP growth rate per annum for 2007-12 to achieve its development priorities. In order to achieve these developmental aspirations, substantial additional energy consumption will be necessary and coal, being the largest domestic energy source, would continue to play a dominant role. Since GHG emissions are directly linked to economic growth, India's economic activities will necessarily involve increase in GHG emissions from the current level. The CO equivalent emissions from India are 2

set to increase up to 3000 million tonnes by 2020. Any constraint will hamper the economic development.

The GHG emissions in the years 1990, 1994 and 2000 increased from 988 to 1228 to 1484 million tonnes respectively and the compounded annual growth rate of these emissions between 1990 and 2000 has been 4.2 per cent. A comparison of the Indian emissions with some of the largest global emitters, indicates that the absolute value of Indian emissions is 24% of the US, 31% of China in 2000. The Indian per capita emissions are only 7% of the US, 13% of Germany, 14% of UK, 15% of Japan, 45% of China and 38% of global average in 2000. The Indian GHG emissions are projected to increase by almost two times with respect to the 1990 emissions in 2020.

15.5.2 GHG mitigation potential in India:

The National strategy study for CDM implementation in India conducted by TERI has made projections of CO emissions in India in different sectors of economy and 2

the mitigation potential thereof. The ALGAS (Asia Least-Cost Greenhouse Gas Abatement Strategy) study, made projections for sectoral GHG emissions from India for the period 1990-2020 in order to identify the key areas for developing an abatement strategy for the country. The energy sector projections for India are summarized in Table 15.2. The baseline scenario represents the most likely situation. Rather than projecting past trend, it includes some carbon abatement technologies and energy efficiency improvements that are likely to occur in the future, irrespective of the concerns for CO emission reduction.2

447446

thTable 15.3: India's perspective plan for electric power during the 11 Plan period

(Source : Ministry of Power, GoI)

The future capacity additions in the power sector are expected to be largely in the thermal sector with coal being the predominant and cost effective fossil fuel in the country.

This being the case, the emission of GHGs from the power sector are likely to increase significantly in the future. Any strategy for mitigation of emissions of GHGs from the power sector would center around improvement in efficiency of the fossil fuel-based power plants by technology upgradation both for the existing plants as well as for the plants to be established in future. The potential technologies that can be adopted are:

i. Pulversied Fluidized Bed Combustion ( PFBC)ii. Supercritical & Ultra-supercritical (SC&USC) power plantsiii. Integrated Gasification Combined Cycle (IGCC) power plantsiv. Underground coal gasification (UGC) technologyv. Coal cleaning technologiesvi. Renovation & Modernisation (R&M) of existing power plants.

15.6.1.1 GHG Mitigation options in Thermal Power Plants

The present energy mix in India for electricity generation is shown in table-15.4:

Table 15.4 : % Energy use for Power Generation

(Source : National Action Plan on Climate Change, GoI)

At present, fossil fuels which account for 65% of the total power generation are thresponsible for most of the GHG emissions. During the 11 Five-Year Plan, utility-

based generation capacity is expected to increase by 78,000 MW. A significant proportion of this increase will be thermal - coal based. While the new investments in the thermal power sector, which are substantial, have high efficiencies, the aggregate efficiency of the older plants is low. In addition, high ATCL (Aggregate Technical and Commercial Loss) in power transmission and distribution is an area of key concern.

There are three ways of lowering the emissions from coal based Thermal Power Plants:

(i) Increasing efficiency of existing power plants; (ii) using clean coal technologies (relative emissions are 78% of conventional

coal-thermal)

Power generation Thermal (coal and lignite)

(MW)

NG/LNG/diesel (MW)

Nuclear (MW)

Hydro (MW) Total (MW)

Installed capacity as on Jan. 2008

75002 NG:14692 Diesel : 1202

4120 35209 141080

Addition of capacity till March 2012

39488 15531 7980 22580 74724

Total capacity as on March 2012

114490 31425 12100 57789 215804

Source Percentage % Coal 55 Hydropower 26 Oil and gas 10 Wind and solar power 6 Nuclear Power 3

CDM has not led to the technology transfer from industrialized to developingcountries as envisaged by the Protocol.

• Industrialized countries have not participated significantly in project financingand the project risks are mostly taken up by the host countries.

• Insurance companies in general have shown little interest in CDM projects,which is unfortunate since they can catalyze carbon trading by providing riskand financial analysis skills.

• There is much subjectivity in the multilateral CDM process and divergentinterpretations are given by different designated operating entities (DOEs)accredited by the CDM EB.

• High transaction costs prevent the small-scale sector (in the Indian definition)from participating in CDM.

• In the absence of an International Transactions Log (ITL), there is lack ofreliable information in the carbon market on CDM transactions.

Despite the above, there is encouraging response from Indian entrepreneurs to the CDM across different sectors.

15.6 GHG mitigation in different Sectors in India:

Based on the targets and plans of the Government of India regarding capacity additions in power and renewable energy sectors and the energy efficiency and technological upgradation being adopted by different industries, the GHG mitigation potential in key sectors, till the first commitment period i.e., till 2012 has been estimated and presented in Figure 15.4.

Fig 15.4 : GHG mitigation potential in key sectors till 2012

(Source : CDM Implementation in India; The National Strategy Study by MOEF & TERI)

15.6.1 GHG mitigation in Power Sector

The power generation efficiency in India is very low by international standards. India's power sector is one of the most CO intensive in the world. Coal based 2

thermal power stations emitted on an average, 943 grams of CO per kwh of 2

electricity produced in 2005-more than 50% higher than the world's average. The total emissions of CO from power plants in 2005 were 659Mt, nearly 60% of the 2

total CO emissions in India. 2

The installed generation capacity of India is 1,41,080 MW as of Jan. 2008, yet there are peaking shortages of 12.2% and energy deficit of 8.8%. The Government of India has set a target of 215804 MW power generation capacities by March 2012 (Table 15.3), requiring a capacity addition of 74724 MW in the next four years.

449448

can be put under two broad categories (i) Energy Conservation and (ii) Load Levelling.

Energy Conversation include:

(a) Mass awareness / education to conserve energy.(b) Development and spread of highly energy efficient products / appliances and(c) Enhanced utilization of untapped energy sources.

Load leveling amounts to promotion of load level management through the use of regenerative systems.

(ii) Clean Coal Technologies

(a) Pressurized Fluidized-Bed Combustion (PFBC)

PFBC is a clean and efficient technology for coal-based power generation which can increase the efficiency of plants up to 43% in a combined cycle arrangement. PFBC technology has the ability to burn low quality fuels. The CO reduction from 2

per unit of power supplied at busbar using PFBC, over the conventional technology is estimated to be 0.18 kg. Replacing a conventional plant of 500 MW capacity with a PFBC plant will result in estimated CO reduction of 0.58 MT (million tonnes) a 2

year.

(b) Supercritical (SC) & Ultra-supercritical (USC) Technology

New pulverised coal combustion systems, utilising supercritical and ultra-supercritical technology, operate at increasingly higher temperatures and pressures and consequently achieve higher efficiencies than conventional PCF units resulting in significant CO reductions.2

In India, three 660 MW SC units are under construction. India has announced plans for a series of 4000 MW 'ultra-mega' power projects in future. Research and Development is under way to improve energy efficiency of ultra-supercritical units from the existing 45% to around 50%.

(c) Integrated gasification combined cycle power plant (IGCC)

In IGCC Power Plants, coal is combined with oxygen and steam in the gasifier to produce the syngas, which is mainly H and carbon monoxide (CO). The gas is then 2

cleaned to remove impurities, such as sulphur and the syngas is used in a gas turbine to produce electricity. Waste heat from the gas turbine is recovered to create steam which drives a steam turbine, producing more electricity. Hence, it is a combined cycle system.

The efficiency of the IGCC power plant is the product of the gasification system efficiency and combined cycle efficiency. These plants are expected to have a net efficiency of 46%, compared to an average of 36% for existing plants. Although, IGCC technology is more efficient and environmentally less polluting than ordinary pulverized coal plants, its application requires high investments compared to conventional pulverized coal technology.

It is estimated that IGCC technology will result in CO emission reductions of 0.25 2

kg/KWh. Replacing a 500 MW conventional plant with an IGCC plant will result in CO emission reduction of 0.69 MT. The proposed IGCC power plant will reduce the 2

emissions of CO , SO , NOx and SPM (Suspended particulate matter). It will also 2 2

reduce solid waste disposal by nearly 70% compared to direct coal-fired plants.

(iii) switching to fuels other than coal. These measures are complementary andnot mutually exclusive.

Another option that has been suggested is carbon capture and sequestration (CCS). However, feasible technologies for this have not yet been developed and there are serious questions about the cost as well as permanence of the CO 2

storage repositories.

Approximately 5000 MW out of total installed capacity of coal based thermal plants have low capacity utilization of less than 5%, as well as low conversion

thefficiency. As per the Govt. plan, during the 11 Plan, these units would be retired, thand during the 12 Plan period, an additional 10,000 MW of the least efficient

operating plants would be retired or reconditioned to improve their operating efficiency.

(i) Efficiency Improvements Significant efficiency improvements and CO reductions can be achieved as the 2

existing fleet of power plants are replaced over the next 10-20 years with new, higher efficiency supercritical (SC) and ultra-supercritical (USC) plants. A one-percentage point improvement in the efficiency of a conventional pulverised coal combustion plant results in a 2-3% reduction in CO emissions, depending on the 2

level of efficiency prior to the change. Some of the efficiency improvements efforts are:

(a) Renovation and modernization (R&M)

Renovation and Modernization (R&M) of power plants can improve the efficiency and reduce GHG emissions at a lower cost without additional infrastructure requirement. However, constraints of the nature of resources, lack of public and government determination and the absence of stringent environmental laws have always acted as a barrier towards the move. The Accelerated Power Development Programme (APDP) of the Ministry of Power, launched in 2000/01, provides financial assistance to the States for undertaking R&M programmes and also for strengthening of T&D (Transmission and Distribution) network.

In a recent study undertaken by TERI, for the Ministry of Power, two technological options were considered and examined in the context of CDM, viz., adoption of super critical power plants and the R&M of existing plants.

(b) Transmission & Distribution loss reduction:

In India, average T&D losses have been officially indicated as 25% of the electricity generated. The major reasons for high technical losses in India include overloading of the distribution system, haphazard transformations, improper load management, inadequate reactive compensation and poor quality of equipment used in the rural as well as suburban areas. Thefts and pilferages also account for a substantial part of the high T&D losses.

It is estimated that the upgradation of the agricultural distribution system can reduce the distribution losses in the sector by 5% to 6%, equivalent to an annual energy saving of 6.75 billion units.

(c) Demand-Side Management

Demand-Side Management (DSM) represents a revolutionary approach for planning the electric utilities. Essentially, it broadens the scope of planning to integrate the customer's needs and desires with the utility's goal. DSM activities

451450

Depending upon the application, the various renewable energy technologies can be broadly classified into three groups.

• Grid-connected power generation.• Off-grid power generation and• Renewable energy projects for thermal energy and mechanical use.

Considering an additional capacity addition of 10,000 MW by 2012, as projected by the MNRE and power generation from various other applications, the cumulative GHG abatement potential from grid-connected RE (renewable energy) power projects, up to 2012 has been estimated. The PLF considered for biomass, wind, small hydro and Waste To Energy (WTE) are 80%, 25%, 35% and 70% respectively. Out of the annual capacity addition in the Waste To Energy (WTE) sector, around 80% is assumed to come from MSW (municipal solid waste) and methane from the sewage liquid waste.

The cumulative GHG abatement potential up to 2012 from RE power projects is 154 MT and from the MSW to energy about 65 MT. The investment required to implement RE projects to the tune of an additional capacity of 10,000 MW by 2012 is estimated to be about 9628 million USD.

15.7 GHG mitigation in Industrial Sector :

During the year 2005, Industry sector in India accounted for about 13% of the total CO emissions. As per the National Strategy Study on CDM implementation in 2

India conducted by TERI, the CO emissions from the industrial sector can be 2

broadly categorized into two heads: (a) emissions due to fuel combustion in the industries and (b) process related emissions. Of the total CO emissions from the 2

industry in 2005, nearly 60% were accounted for due to energy use only.

The process related emissions are the result of non-energy related activities that result in the emission of CO . Cement and Steel industry, accounted for nearly 75% 2

of the total process related CO emissions. The other major processes that result in 2

CO emissions are soda ash use, ammonia production, lime production and 2

processes in the ferroalloys industry.

Detailed analysis of the industrial energy-use pattern reveals that around 65% of the total energy consumption in the industrial sector is accounted for by seven sectors namely (1) cement (2) pulp and paper (3) fertilizer (4) iron and steel (5) textiles (6) aluminum and (7) chemicals and petrochemicals. In addition to these sectors, there are a few energy intensive sub-sectors operating under the small scale, where energy cost accounts for a major share of the operating cost. Some of the examples of energy intensive small-scale industries are ceramics & glass, foundry, forging, brick manufacture, and lime kilns etc.

Energy efficiency programs across all industry sectors hold the promise for cost-effective CO abatement, as a large number of plants in India operate well below the 2

world energy efficiency standards. The CO mitigation projects in the industrial 2

sector could be broadly grouped under four major heads.

(a) Sector-specific technological options,(b) Cross-cutting technologies,(c) Fuel- switch options, and(d) Recycling and use of secondary materials.

(iii) Switching to fuels other than coal

(a) Natural Gas based Power Plants

Natural gas based power generation is cleaner than coal-based generation as CO2

emissions are only 50% compared to coal. Besides, natural gas can be used for electricity generation by adopting advanced gas turbines in a combined cycle mode. Introduction of advanced class turbines with inlet temperature in the range

0 01250 C-1350 C has led to combined cycle power plant efficiency of about 55% under Indian conditions. Many such plants are in operation in India. With the discovery of significant reserves of natural gas in the KG basin, setting up of more combined cycle natural gas plants is an attractive GHG mitigation option in India.

(b) Underground Coal Gasification (UCG)

UCG is a method of injecting air or oxygen into a coal seam to support an in-situ gasification process. This process converts the unmined coal into a combustible gas, which can be brought to the surface to be used for industrial heating or power generation. Current UCG projects are relatively small-scale, but if the process can be developed as a reliable, large-scale source of coal syngas, it could also potentially be used to feed capital intensive plants producing hydrogen, synthetic natural gas or diesel fuel. UCG in combination with CCS is also recognised as a potential route to carbon abatement from coal.

(c) Coal Cleaning

Coal cleaning reduces the ash content of coal by over 50%, resulting in less waste, lower sulphur dioxide (SO ) emissions and improved thermal efficiencies, leading to 2

lower CO emissions. While coal preparation is standard practice in many countries, 2

in India, if a greater proportion of this coal were cleaned, there is the potential for thermal efficiency improvements of at least 2-3% extending up to 4-5%.

A number of technologies have been developed to control particulate emissions and are widely deployed in both developed and developing countries. These are :

• Electrostatic precipitators• Fabric filters or baghouses• Wet particulate scrubbers• Hot gas filtration systems.

15.6.1.2.GHG mitigation through Renewable Energy Power Plants:

The renewable energy technologies offer a centralized as well decentralized supply side options. With policy initiatives, financial and infrastructural support from the Ministry of New Renewable Energy (MNRE), many of the renewable energy technologies have reached near commercialization stage. The status of different renewable energy technologies and their respective potential is given in Table 15.5.

Table 15.5 : Potential and achievements for renewable energy technologies

(Source : Report on working group on New & Renewable Energy for XI Plan, GoI)

Source / system Approximate potential

Cumulative physical achievements (as on 30.9.06)

Proposed during XIth Plan Period

Wind energy 45000 MW 6070 10,500 Small hydro power 15000 MW 1850 1400 Biomass power/ cogeneration 19500 MW 1039 1700 Waste-to-energy 1700 MW 35 400 Biomass gasifiers 76 N/A Solar photovoltaic systems 2.74 50 Solar water heating (collector area) sq.m

140 million sq.m

1.5 million s.q.m. 10 million

Biogas plants (nos.) 12 million 3.9 million 2 million Improved cook stoves (nos.) 120 million 33.9 million as on 31.3.04 N/A

2.74

453452

• Control of excess air by installing O monitoring system in high-pressure2

boiler of CPP in a steel plant.

Environment Management measures by Steel Industry in India

• Commissioning of wastewater recycling projects at plants and townshipsto utilize treated water for green belt development.

• Commissioning of incinerator to incinerate waste organic materials.• Utilisation of 100% slurry in pellet and sinter plant.• Technology upgradation and revamping in acid recovery plant, to ensure

continual improvement in emissions levels.• Provision of High Efficiency Venturi Scrubbers in Hot Briquetted Iron

(HBI) plant to control emission of particulate matter. (This also helps inrecovery of iron ore fines and its reuse after pelletization).

• Installation of Central Vaccum De-dusting System for control of emissionof Particulate Matter (PM).

• Use of low NOx generating burners in natural gas/ liquefied natural gas /Naphtha based Power Plants for control of emission of Oxides ofNitrogen.

15.7.3 Aluminum

The Aluminum manufacturing process is electrical energy intensive. The major energy saving opportunities in this sector lie in the switchover to gas suspension calciners as against rotary kilns and waste heat utilization in converting the smelters from Soderberg systems to pre-baked systems. The other operational improvements include current efficiency improvements and reduction in operating voltage.

Energy Saving and GHG Emissions Reduction Technologies in Aluminum sector :

• Improvement of operation of hot air circulation fan for the Aluminumannealing furnace

• Replacement of existing rotary kilns with stationary calciners.• Adoption of tube digestion system for dissolution of predominantly

monohydrate Bauxites.• Redesigning of bus bar arrangement.• Provision of mechanized and automated cell operations.• Provision of dry scrubbing system for gas cleaning and recovery of

fluorides.• Improved design features for heat treatment furnaces.• Installation of combined direct/indirect extrusion press.

15.7.4 Fertilizer

Of the four types of fertilizers-nitrogenous, phosphate, potash, and complex fertilizers, the nitrogenous fertilizer production is highly energy intensive and is one of the largest consumers of petroleum-based fuels. Many of the older ammonia/urea manufacturing plants use liquid fuels (naphtha, furnace oil) as the feedstock but in newer plants, natural gas is the preferred feedstock.

The Indian fertilizer industry has witnessed many changes in the feedstock and technology during the last few decades, resulting in substantial reduction in the overall energy-use efficiency. However, by switching over from fuel oil/naphtha to natural gas and by adopting other energy conservation schemes, potential for CO2

mitigation exists in older plants.

Energy Saving and GHG Emissions Reduction Technologies in Fertilizer sector:

Figure 15.5 below gives a general classification for the types of projects that could be considered under the above four heads.

Fig 15.5: CO mitigation options: Energy-Efficient technologies in industry sector2

15.7.1 Cement

GHG mitigation potential in the cement sector lies in bringing down specific power consumption and specific thermal energy consumption. There lies a large scope for improving energy efficiency in the relatively older installation. The possibility for energy saving in different plants varies from 10% to as high as 30%. In addition, there also exists about 160 MW of cogeneration potential in the Indian cement industry.

The energy efficient technologies which can reduce CO emissions in cement 2

production are:(a) Large Scale rotary kilns in place of vertical kilns for clinker production.(b) Dry process in place of wet process.(c) Pre-calcination technology.(d) Pre-heating (e) Use of Clean energies from biomass wastes.(f) Use of fly-ash as substitute of clinker.

15.7.2 Iron and steel

Most of the emissions from the steel industry are related to processes such as quenching, gas recovery, casting and rolling. In addition, the use of different types of furnaces and fuels also determines the extent of emissions. During the year 2005, Carbon dioxide emissions from steel production were responsible for 7% of total emissions in India. While CO intensity tc/tonne from the steel sector in India is 2

comparable to China, it is much higher compared to Brazil, Mexico and South Africa.

Energy Saving and GHG Emissions Reduction Technologies in steel sector :

• Coal drying and humidity control equipment for coke oven.• Sensible heat recovery from main exhaust gas of sintering machine.• Exhaust heat recovery system for sintered ore cooling equipment.• Pulverised Coal Injection for blast furnace.• BOF exhaust gas recovery device (including sealed BOF).• Ladle heating apparatus with regenerative burners.• Recovery of sensible heat from skid cooling water in heating furnace.

Adoption of energy-efficient technologies

Cross-cutting technologies

Large industries

· Cement

· Fertilizer

· Iron and Steel

· Textiles

· Pulp and paper

Fuel-switch options

Recycling and use of secondary materials

Small-scaleindustries · Foundry

· Brick kilns

· Glass

· Others

455454

in the production of Hydro Chloro Fluoro Carbon (HCFC22). HFC 23 is used in a specific fire fighting application, ultra low temperature application and in the processing of semi-conductors, but the volume of use is limited. The Gujarat Fluorochemcials Ltd, in its HCFC production plant is introducing thermal oxidation of HFC 23, the by-product of HCFC 22, as a CDM project.

N O emission reduction is possible through thermal and catalytic destruction 2

processes in adipic acid production. A N O emission reduction project from India is 2

under the consideration of Prototype Carbon Fund (PCF).

15.8 GHG mitigation in Transport Sector

The transport sector in India accounts for 8% of India's CO emissions. This share2

is likely to grow to 13% in 2030 with rapidly rising transport demand, particularly after 2015 as vehicle ownership increases. The share of transport in total CO 2

emissions in 2015 was 31% in US and 24% in European Union, which is much higher than India. Though theoretically, a very attractive sector in terms of mitigation, individual projects might be too large-scale for CDM and include such activities as engine modifications, road-to-rail modality shift, replacement of2-stroke by 4-storke two-wheelers and greener fuels eg. Compressed natural gas (CNG) etc.

Mitigation of GHG emissions in the transport sector can be achieved through the combination of various measures. There needs to be attractive transportation options that include energy-efficient automobiles, motorized two-wheelers, efficient and affordable public transport, minicars, 4-stroke engines in two-wheelers and setting fuel efficiency norms and labeling of Motorised Vehicles etc. In addition to this, policies should address externalities caused by vehicles like, drivers to face the full social cost of their use through permits and fees to enter cities, parking fees, road tolls and in general, raising public awareness. Finally, the government should attempt to make available to users, an alternative to fossil fuel consuming vehicles by subsidizing bicycles, linking rail and bus services and rewarding the car sharing programmes. The studies list a number of mitigation areas including BOV (battery-operated vehicle), MRTS (mass rapid transport system), CNG bus, CNG car, and the efficient two-wheelers. In two Asian Institute of Technology (AIT) case studies on Delhi and Mumbai, mitigation options analysed are CNG for buses and cars, shift from 2-stroke to 4-stroke two-wheelers and BOVs.

15.9 GHG mitigation in Residential, Commercial and Institutional Buildings Sector

According to the study conducted by IPCC, Global carbon dioxide (CO ) emissions 2

from residential, commercial, and institutional buildings are projected to grow from 1.9 Gt C/yr in 1990 to 2.9 Gt C/yr in 2010, 3.3 Gt C/yr in 2020, and 5.3 Gt C/yr in 2050. While 75% of the 1990 emissions are attributed to energy use in Annex I countries, only slightly over 50% of global buildings-related emissions are expected to be from Annex I countries by 2050.

Energy-efficiency technologies for building equipment like : Improvements in the building envelop (through reducing heat transfer and use of proper building orientation, energy-efficient windows and climate-appropriate building albedo) with paybacks to the consumer of five years or less have the economic potential to reduce CO emissions from both residential and commercial buildings of the order 2

of 20% by 2010, 25% by 2020 and up to 40% by 2050.

15.7.4.1 Megammonia (Ammonia Production)

Operating cost is expected to be lower by around 12 -15% over the most advanced conventional technology. CO emission is expected to reduce by around 30% as 2

compared to other conventional technologies.

15.7.4.2 HydroMax Technology (Ammonia Production)

Carbon dioxide and hydrogen are produced in separate compartments and do not require CO removal system. Cost of production is almost four times less than 2

Steam Methane Reforming (SMR) production cost. Emission of greenhouse gases is 34% less than SMR process.

15.7.4.3 Feedstock conversion from Naphtha to NG in Ammonia-Urea plants

Natural gas is ideal feedstock for ammonia production. It has several advantages besides being cheaper and easy to handle. It also allows easy and shorter start up of the plant, thereby lesser unproductive consumption. The burners choking phenomena is completely solved and CO emission from furnace has reduced. Plant 2

also runs trouble free and the catalyst life has also increased

15.7.4.4 Installation of Carbon Dioxide Recovery (CDR) Plant

Though regeneration energy is very high in comparison to that of any normal CO 2

removal section of ammonia plant, the cost effectiveness of the plant is very attractive because the use of costlier Naphtha (as feed to balance the CO for Urea 2

production) shall be stopped completely.

15.7.4.5 Conversion of Single Stage GV System to 2-Stage GV System for CO2

The system designed by M/s. Giammarco Vetro Cokes, Italy, results in better absorption of CO in absorber and lower energy consumption for regeneration of 2

the solution in regenerators. Major benefits of the modification are reduction of CO 2

slip through absorber by around 600 ppm, which has resulted in higher availability of CO for urea production, decrease in hydrogen consumption in methanation 2

section and decrease in LP steam consumption in CO removal system from 38 2

MT/hr to 15 MT/hr. Energy saving of around 1GJ/MT of ammonia can be achieved.

15.7.4.6 Other options

• Installation of a Parallel S-50 Converter• Installation of modified trays in Urea reactor • Use of Advanced Process Control (APC) with Distributed Control System

(DCS)• Installation of Waste Heat Boiler (WHB) at the Inlet of LTS Converter in

Ammonia Plant• Installation of Make-up Gas Chiller at suction of Synthesis Gas

Compressor at Ammonia Plant• Installation of High Efficiency Turbine for air blower in Sulphuric Acid

Plant• Re-processing of purge gas for Ammonia fertilizer

15.7.5 GHG mitigation of Industrial gases

In the industrial gases category, the options considered are HFC (Hydro Fluoro Carbon) waste stream incineration, and N O (nitrous oxide) emission reduction. 2

HFC 23, a GHG under the Kyoto Protocol, is inevitably generated as a by-product

457456

15.11 National Action Plan on Climate Change (NAPCC) :

15.11.1 Principles

Maintaining a high growth rate is essential for increasing living standards of the vast majority of people and reducing their vulnerability to the impacts of climate change. In order to achieve a sustainable development path that simultaneously advances economic and environmental objectives, the National Action Plan for Climate Change (NAPCC) will be guided by the following principles:

• Protecting the poor and vulnerable sections of society through aninclusive and sustainable development strategy, sensitive to climatechange.

• Achieving national growth objectives through a qualitative change indirection that enhances ecological sustainability, leading to furthermitigation of greenhouse gas emissions.

• Devising efficient and cost-effective strategies for end use Demand SideManagement.

• Deploying appropriate technologies for both adaptation and mitigation ofgreenhouse gases emissions extensively as well as at an accelerated pace.

• Engineering new and innovative forms of market, regulatory andvoluntary mechanisms to promote sustainable development.

• Effecting implementation of programmes through unique linkages,including with civil society and local government institutions and throughpublic-private-partnership.

• Welcoming international cooperation for research, development, sharingand transfer of technologies enabled by additional funding and a global IPR regime that enables technology transfer to developing countries under the UNFCC.

15.11.2 Summary of eight National Missions of NAPCC:

There are Eight National Missions, which form the core of the National Action Plan, representing multi-pronged, long-term and integrated strategies for achieving key goals in the context of climate change. While several of these programmes are already part of our current actions, they may need a change in direction, enhancement of scope and effectiveness and accelerated implementation of time-bound plans.

(i) National Solar Mission

India is a tropical country, where sunshine is available for longer hours per day and in great intensity. Solar energy, therefore, has great potential as future energy source. Photovoltaic cells are becoming cheaper with new technology. There are newer, reflector-based technologies that could enable setting up megawatt scale solar power plant across the country. Another aspect of the Solar Mission would be to launch a major R&D programme, to enable the storage of solar power for sustained, long-term use.

(ii) National Mission for Enhanced Energy Efficiency

The Energy Conservation Act of 2001 provides a legal mandate for the implementation of the energy efficiency measures through the institutional mechanism of the Bureau of Energy Efficiency (BEE) in the Central Government and designated agencies in each state. A number of schemes and programmes have been initiated and it sis anticipated that these would result in a saving of 10000 MW

thby the end of 11 Five Year Plan in 2012.

A significant means of reducing GHG emissions in the buildings sector involves more rapid deployment of technologies aimed at reducing energy use in building equipment (appliances, heating and cooling systems, lighting and all plug loads, including office equipment) and reducing heating and cooling energy losses through improvement in building thermal integrity. Other effective methods to reduce emissions include urban design and land-use planning that facilitate lower energy-use patterns. Improving the combustion of solid biofuels or replacing them with a liquid or gaseous fuel are important means for reducing non-CO GHG 2

emissions.

15.10 Other GHG Mitigation Options :

15.10.1 Energy Labeling Programme for Appliances

An energy labeling programme for appliances was launched in 2006 and comparative star-based labeling has been introduced for fluorescent tube-lights, air conditioners, refrigerators, and distribution transformers. The labels provide information about the energy consumption of an appliance and thus enable consumers to make informed decisions. The Bureau of Energy Efficiency (BEE) has made it mandatory for refrigerators and air conditioners to display energy efficiency labels. The standards and labeling programme for manufacturers of electrical appliances is expected to lead to significant savings in electricity.

15.10.2 Energy Conservation Building Code

An Energy Conservation Building Code (ECBC) was launched by BEE in May 2007, which addresses the design of new large commercial buildings to optimize the energy demand based on their location in different climate zones. Commercial buildings are one of the fastest growing sectors of the Indian economy, reflecting the increasing share of the services sector in the economy. Nearly one hundred buildings are already following the code. Compliance with the code has been incorporated into the mandatory environmental impact assessment requirements for large buildings. It has been estimated that if all the commercial space in India conform to ECBC norms, energy consumption in this sector can be reduced by 30-40%. Compliance with ECBC norms is voluntary at present but it is expected to soon become mandatory.

15.10.3 GHG mitigation in Municipal Waste :

Though MSW (Municipal Solid Waste) projects are often seen as low-hanging fruits, ideally suitable for early CDM projects, none of the reports investigate this area in great detail. Arguably, the validity of projects generated in this areas is dependent on the absence of legislation mandating the flaring of landfill gas. There is also the possibility, that even in metropolitan areas, waste is not compacted enough to generate the anaerobic conditions needed for optimal methane generation.

Methane emissions in India, have their origins mainly from livestock (42%), paddy cultivation (23%) and biomass burning (16%). The attributable 10% emissions, to waste is more easily measureable and thus provides the easiest baseline estimation for CDM projects. The hotspots for methane generation from MSW disposal are above all the metro-districts of Ahmedabad, Bangalore, Chennai, Calcutta, Delhi, and Greater Mumbai (Garg and Shukla 2002).

459458

Building public awareness will be vital in supporting implementation of the NAPCC. This will be achieved through national portals, media engagement, civil society involvement, curricula reform and recognition / awards.

15.11.4 Institutional Arrangements for Managing Climate Change Agenda

In order to respond effectively to the challenge of climate change, the Government has created an Advisory Council on Climate Change, chaired by the Prime Minister. The Council has broad based representation from key stake-holders, including Government, Industry and Civil Society and sets out broad directions for National Actions in respect of Climate Change. The Council will also provide guidance on the domestic agenda and review of the implementation of the National Action Plan on Climate Change including its R&D agenda.

The Council would also provide guidance on matters relating to international negotiations including bilateral, multilateral programmes for collaboration, research and development.

References

1. Annual Report of Ministry of Environment & Forest (MoEF), 2007-08, GoI2. IPCC Technical Paper VI; Climate Change & Water ; June 2008.3. 'Coal Meeting the Climate Change', Technology to reduce GHG emissions,

World Coal Institute.4. 'National Action Plan on Climate Change'; Prime Ministers' Council on

Climate Change; GoI.5. CDM Implementation in India; The National Strategy Study; MoEF & TERI.6. 'Energy Use and Carbon Dioxide Emissions in the Steel Sector in Key

Developing Countries' by Lynn Price, Dian Phylipsen, Ernst Worrell.7. GHG Inventory Information ; India's Initial National Communication, GoI.8. Greenhouse Gas Emissions from India: A perspective; Subodh Sharma,

Bhattacharya, Amit Garg, PMC:, MoEF.9. Report on Working Group on National Action Plan for Operationalising Clean

Development Mechanism (CDM); Planning Commission, GoI.10. Integrated Energy Policy; Planning Commission, GoI.11. IEA, World Energy Outlook 2007.12. Report on Working Group on R&D for the Energy Sector, XI Plan; Office of

the Principal Scientific Adviser to GoI.13. Maarland et al., 199914. Lynn, Ernst, and Dian 199915. NATCOM 200416. Report on working group on New & Renewable Energy for XI Plan.17. IEACCC 2003a18. Institute of Global Environment Strategies (IGES)19. Asia Least-Cost Greenhouse Gas Abatement Strategy20. Websites : http://www.unfccc.comwww.iges.or.jpwww.carbonyatra.comwww.globalwarming.orghttp://en.wikipedia.org/wiki/UNFCCChttp://en.wikipedia.org/wiki/global_warminghttp://cdm.unfccc.int.statistics/index.htmlhttp://cdm.unfccc.int/statistics/registeredprojbyscalepiechart.htmlhttp://cdm.unfccc.int.statistics/methodologies/approvemethpiechart.htmlhttp://www.physicalgeography.net/fundamentals/7h.html

(iii) National Mission on Sustainable Habitat

A National Mission on Sustainable Habitat will be launched to make habitat sustainable through improvements in energy efficiency in buildings, management of solid waste and modal shift ot public transport. The Mission will promote energy efficiency as an integral component of urban planning and urban renewal. In addition, the Mission will address the need to adapt to future climate change by improving the resilience of infrastructure, community based disaster management, and measures for improving the warning system for extreme weather events. Capacity building would be an important component of this Mission.

(iv) National Water Mission

A National Water Mission will be mounted to ensure integrated water resource management helping to conserve water, minimize wastage and ensure more equitable distribution both across and within states. The Mission will take into account the provisions of the National Water Policy and develop a framework to optimize water use by increasing water use efficiency by 20% through regulatory mechanisms with differential entitlements and pricing.

(v) National Mission for sustaining the Himalayan Ecosystem

A Mission for sustaining the Himalayan Eco-system will be launched to evolve management measures for sustaining and safeguarding the Himalayan glacier and mountain eco-system. This will require the joint effort of climatoglogists, glaciologists and other experts. We will need to exchange information with the South Asian countries and countries sharing the Himalayan ecology.

(vi) National Mission for a Green India

A National Mission will be launched to enhance eco-system services including carbon sinks to be called Green India. The Prime Minister has already announced a Green India campaign for the afforestation of 6 million hectares. The national target of area under forest and tree cover is 33% while the current area under forests is 23%.

(vii) National Mission for Sustainable Agriculture

The Mission would develop strategies to make Indian agriculture more resilient to climate change. It would identify and develop new varieties of crops and especially thermal resistant crops and alternative cropping patterns, capable of withstanding extremes of weather, long dry spells, flooding, and variable moisture availability.

(viii) National Mission on Strategic Knowledge for Climate Change

To enlist the global community in research and technology development and collaboration through mechanisms including open source platforms, a Strategic Knowledge Mission will be set up to identify the challenges of, and the responses to, climate change. It would ensure funding of high quality and focused research into various aspect of climate change.

15.11.3 Implementation of Missions

Each Mission will be tasked to evolve specific objectives spanning the remaining th thyears of the 11 Plan and the 12 Plan period 2012-13 to 2016-17.

Technical literature (Thermal) Price Technical literature (Electrical) Price

1. Storage, handling and preparation of fuel oils

2. Combustion of fuel oils and burners -

Operation

Rs 15

Rs 30

3. Efficient generation of steam 4. Efficient utilisation of steam

5. Fuel economy in furnaces and waste heat recovery

Rs 15

Rs 15

Rs 15

6. Refractories

7. Thermal insulation

Rs 15

Rs 15

Rs 15 1. Energy savings in electric motors

2. Energy savings in electric furnaces

3. Energy savings in compressed air system

4. Energy savings in pumps, fans and variable

speed drives

5. Energy savings in refrigeration and air

conditioning systems

Rs 30

Rs 30

Rs 30

Rs 30

and Maintenance

The above literature is available in English

Pamphlet Language Pamphlet Language

Corporate Domestic

Quarterly technical journal titled as ‘Active

Conservation Techniques’ (ACT)

Corporate profile

Energy booklet for school children (Urban)

Energy booklet for school children (Rural)

Poster on Energy Conservation (Hello Friend)

All about oii - Tel ke sambandh main (Poster)

Bio-diesel

Leaflet on bio-diesel (8 pages)

Leaflet on bio-diesel (1 page)

Leaflet on bio-diesel (4 pages)

Transport

Booklet on Driver Training Programme

Booklet for four wheeler vehicles

Single page leaflet for Transport Sector

Save diesel - Simple tips on better driving of

buses/trucks - 6 points (Poster)

Save petrol - Get more kilometres

per litre - 14 points (Poster)

Save diesel - Tips on better maintenance of

buses/trucks - 15 points (Poster)

Agriculture

Single page leaflet for Agriculture Sector

Save diesel - Saving diesel used in lift irrigation

pump set - 7 points (Poster)

Operation and maintenance of tractors - 10 points

English

English

English

English

English/Hindi

English/Hindi

Hindi

Hindi

English

English

English

English

English/Hindi

English/Hindi

English/Hindi

English/Hindi

English/Hindi

Single page leaflet for Domestic Sector

Cooking gas - How to make it last longer.

Good cooking habits (Poster)

Industrial

Tips for conservation of energy in the industrial sector

Stickers

Use of Car Pool (Transport)

Stop leakages (Industry)

R&D

R&D booklet (Design/development of

innovative technologies, equipments, appliances

and evaluation/certification of additives)

R&D leaflet - Design and development of kerosene

vapour recovery plant for textile industry

R&D leaflet- Design and development of

lubricating oil and grease dispensing equipments

used in textile industry

R&D leaflet- Design and development of

PCRA's low excess air industrial film burner

suitable for dual fuel operations and

preheated air for combustion

Energy efficiency in pulp and paper industry

Leaflet on Sona ESV

Save fuel in whiteware industry

Improving the rural life through...(Energy

efficient durable cook stoves for rural areas)

English

Engish/Hindi

Engish/Hindi

English

English

English

English

English

English

English

Hindi

English

EnglishEnglish/Hindi

If you wish to order any of the above literature, please write to us at the following address:Additional Director (EC), PCRA, Sanrakshan Bhawan, 10, Bhikaiji Cama Place, New Delhi - 110066

PCRA publications

Rs 30