National Productivity Council

Energy Conservation in a Coal based Super Thermal Power Station Success story

Presented by

Shri. D. Pawan Kumar

Shri. A. K. Sinha

Dr. S. Biswas

Shri. A. Chakraborty

Shri. G. Saha

NATIONAL PRODUCTIVITY COUNCIL

Autonomous Body under Ministry of Commerce &

Industry, GOI, established in 1958.

Tripartite in nature.

Non-profit organisation.

Headed by Shri N. C.Vasudevan, IAS, Secretary to GOI

and DG NPC

Providing Training, Consultancy & research , in the

areas of Productivity Improvement.

NPC also Implements the productivity promotion

programmes of the Tokyo based Asian

Productivity Organization (A P O).

HUMAN RESOURCE

MANAGEMENT ENERGY

MANAGEMENT

ENVIRONMENT

MANAGEMENT

INFORMATION

TECHNOLOGY

TECHNOLOGY

MANAGEMENT

AGRI-BUSINESS

COMPETENCY AREAS

PROCESS

MANAGEMENT

STRATEGIC PRODUCTIVITY

MANAGEMENT

PRODUCTIVITY

AWARENESS

AIP/SD

ECONOMIC

SERVICES

About 250 revenue earning consultancy & research projects per

year

About 300 Training Programmes per year (general and customized)

International Programs (APO/UNIDO/UNEP)

Productivity Awards

Sponsored Productivity Awards

Facilitate Indian participation in about 100 APO programs

Journals/News Letters

ACTIVITY LEVELS

Promotion, Training, Consultancy and Research

ENERGY MANAGEMENT STUDIES

ENERGY AUDIT

ENERGY CONSERVATION

DEMAND SIDE MANAGEMENT

CLEANER PRODUCTION -ENERGY EFFICIENCY

COST REDUCTION OPPORTUNITIES IN

POWER SECTOR

AUDITS & R & M IN POWER GENERATION

SECTOR

TRANSMISSION AND DISTRIBUTION SECTOR

LOSS REDUCTION

CAPACITY BUILDING

RELIABILITY IMPROVEMENT THROUGH

CONDITION MONITORING OF PLANT EQPT

KEY RESULT AREAS IN THERMAL POWER PLANT

A) HT/LT AUXILIARIES

FD fans

ID fans

Boiler feed Water pumps

Condensate extraction pumps

Circulation Cooling Water Pumping system

Cooling Towers

CT Fans

PA fans

Coal Mills

KEY RESULT AREAS IN THERMAL POWER PLANTS

B) OFF-SITES

Raw Water

pumping system

Coal handling plant

Ash handling plant

Compressed air

Refrigeration & air

conditioning

Lighting

C) THERMAL AREAS

Boilers

Turbines

Condensers

Regenerative Feed

heaters

Economizers

Air Pre-heaters

D) OTHER SUB-SYSTEMS

Insulation studies to reduce heat losses

Thermography studies of switch yards &

transformers

Fuel oil system

KEY RESULT AREAS IN THERMAL POWER PLANT

Energy management services of NPC, is

being provided since last two decades, in

assisting major thermal power stations in

India in the following areas:

Heat rate improvement

Reduction in Auxiliary Power Consumption

Reduction in Carbon Emission

Present Status of Energy Performance in Coal Based

Power Station:

Actual Heat Rate = 3050 Kcal/kWh

Design Heat Rate = 2294 Kcal/KWh

Specific Carbon emissions

1.19 t CO2/ MWh for 67.5 MW Unit

1.00 t CO2/ MWh for 500 MW Unit

Actual Auxiliary Power Consumption (APC) = 12%Design Auxiliary Power Consumption (APC) = 8%

Wide variation in Heat Rate, APC, Unit Efficiency, PLF indicates

potential for performance improvement.

Present Energy Performance

Actual PLF = 78%

GOI initiative for Energy Efficiency improvement

Regulatory Interventions

Heat Rate improvements.

APC improvements

Energy Conservation Act 2001

Designated Consumers

Rising fuel cost

Import of fuel

CDM Additional Revenue stream?

Baseline data for Power sector CDM projects available

Merit Order rating of Units due to ABT

Case Analysis of a Coal Based Units : Recent Energy

Audit Study by NPC Overall performance prior to carring out the study

Unit rating 140 MW 210 MW

Unit vintage 1966 1986

Availability (%) 81 87

PLF (%) 61 73

APC (%) 9.66 10.91

Coal rate (kg/kWh) 0.65 0.62

Oil rate (ml/kWh) 1.97 4.17

Heat Rate (Kcal/Kwh) 3039 3058

Thermal Effy (%) 28.4 28.1

Case Analysis of Coal Based Units

OBSERVATION:

1. Boiler area:

Coal quality deviation w.r.t. design.

Tube leakages- Economizer, Re-heater, Boiler

Absence of HP heaters

Dis-functional soot blowers

Operational combination of mills

Spurious tripping- Inadequate instrumentation

Case Analysis of Coal Based Units

2. HPT and IPT of Turbine

Nozzle block erosion

Turbine blade erosion

Deposits on nozzles & blades

Gland packing leakages

Strip seal leakages

Malfunctioning of control valve

Case Analysis of Coal Based Units

3. Condenser area:

Condenser effectiveness deviation w.r.t. design.

Terminal temperature difference (TTD) deviation w.r.t. design.

LMTD deviation w.r.t. design.

The condenser thermal load deviation w.r.t. design.

CW flow has been assessment based on condenser thermal load compare with design / actual (measured

by Ultrasonic flow meter).

Case Analysis of Coal Based Units

Improvement margins of Boiler area:

1. Reintroduction of HP heaters in feed water circuit

and repair/replacement of Economizer tubes:

Potential of saving identified was 110 Kcal/ KWh in

140MW Unit and 120 Kcal/Kwh in 210MW Unit.

2. Inleak air abatement & secondary air temperature

increase and reduction of Combustibles in Fly ash &

Bottom ash:

Boiler efficiency improvement by 5.6% in 140MW Unit

and 4.3% in 210MW Unit.

Case Analysis of Coal Based Units

Improvement margins of Turbine area:

1. Control of Main steam pressure & temperature :

2. Control of Reheat steam temperature:

3. Cylinder efficiency improvement of HP/IP/LP

Turbines based on inspection and rectification based

on internal conditions of damage, during turbine

overhaul:

Potential of saving identified was 320 Kcal/ KWh in

140MW Unit and 34 Kcal/Kwh in 210MW Unit.

Case Analysis of Coal Based Units

Improvement margins of Condenser area:

1. Condenser Vacuum improvement with better

condenser performance :

Potential of saving identified was 54 Kcal/ KWh in 210MW

Unit.

Case Analysis of Coal Based Units

Improvement options in Boiler area:

1. Improvement in Boiler Feed Water Temperature through

commissioning of HP Heaters and repair / replacement of

Economizer tubes.

2. Control of Excess De-Super Heater spray water requirement

through increase of heat transfer, by recommissioning /

repairing of existing Soot Blowers.

3. Savings Potential By Inleak Air Abatement & Secondary Air

Temperature Increasing.

4. Reduction of Combustibles in Fly & Bottom Ash.

1. Heat Rate improvement by control of main steam pressure &

temperature, reheat steam temperature.

Case Analysis of Coal Based Units

Improvement options in Turbine area:

Improvement options in Condenser area:

1. Condenser Vacuum improvement with better condenser

performance.

Improvement options in Unit Auxiliaries

Boiler Feed Pump (BFP):1. ENCON by Eliminating Re-circulation Water across Boiler

Feed Pumps.

2. Replacement of Old Boiler Feed Pumps by New High

Efficiency pumps (72% plus) and existing Fluid Coupling by

LTVFD.

Condensate Extraction Pump (CEP):1. Single Condensate Extraction Pump operation with improved

efficiency.

Case analysis of coal based units

Improvement options in Unit Auxiliaries

Circulating Water Pump (CW):

1. Modification of ARCW requirements and optimization of CW

system vis--vis condenser system.

2. Pump efficiency improvement by applying polymer coating on

pump internals.

Case analysis of coal based units

Induced Draft Fan (ID):1. Reduction in air ingress in flue gas path by plugging ingress

points.

2. Replacement of by state of the art ID fans of 80% plus

efficiency and LTVFD in place of existing fluid coupling

Forced Draft Fan (FD):1. LTVFD option in place of Damper operation.

Primary Air Fan (PA):1. Replacement of existing PA fans with damper control by state of

the art high efficiency fans with LTVFD.

Coal Mill:1. Encon by three mill operation, on account of reduction in mill

power during low load unit operation (100 MW & below).

Case Analysis of Coal Based Units Improvement options in Unit Auxiliaries

Cooling Tower (CT):1. Over all effectiveness improvement.

Air Compressor:1. Phase wise replacement of inefficient compressors.

2. Isolate Service Air and Instrument Air line and operate

Instrument Air at 5.5kg/cm2

3. Minimize air leakage from network system.

4. Replace/Retrofit existing air dryer.

Case Analysis of Coal Based Units Improvement options in Station Auxiliaries

Coal Handling Plant (CHP):1. Energy Savings by increasing coal throughput rate of Conveyors.

2. Energy Savings by increasing crusher throughput.

3. Energy Savings by incorporation of Vibro-Grizzly feeders.

Ash Handling Plant (AHP):1. Energy savings by reducing Ash Water Ratio.

2. Energy savings by By-pass arrangement in ash slurry disposal

pumps, when only single pump in series is in operation.

3. Improvement of Operating Efficiency of Under Performing

Pumps (Ash Slurry Disposal pumps.

Case Analysis of Coal Based Units Improvement options in Station Auxiliaries

IMPLEMENTATION

AND

SAVINGS ACHIVED

IMPLEMENTATION AND RESULTS

Based on several interaction subsequent to the study

and site visit it was observed that the management

could implement major recommendations as indicated

earlier in Unit Auxiliaries areas and station auxiliaries

areas apart from implementing specific

recommendations in main plant area like Boiler,

Turbine and Condenser which has resulted

appreciable overall improvements of unit performance

towards higher plant loading, PLF improvement,

reduction of APC & Heat rate, details as follows.

MAIN PLANT AREA, 210 MWRecommendations Plant side initiative Result

BOILER AREA:

Reduction and

control of

combustion matter in

fly ash and bottom

ash

Combustible matter

in fly ash reduced to

3% from 5% and to

6.5% from 10% for

bottom ash

Boiler efficiency

improvement by

4.5%

TURBINE AREA:

Turbine Area :

Control of main

steam parameters

including

atemperation flow

Atemperation flow

was reduced to 0

from 7% during the

study period

Potential of

savings identified

was 34Kcal/KWh.

MAIN PLANT AREA, 210 MWRecommendations Plant side initiative Result

CONDENSER AREA:

Improvement of

condenser vacuum

through optimized

condenser

performance

Condenser vacuum

improved by 80mm

of HG from existing

level.

Potential of

savings identified

was 54Kcal/KWh.

Recommenda

tions

Plant side initiative Achieved

Reduction/

Saving

%

Savings

in APC

Amps KW

In leak abatement

in flue path and

APH modification

Modification of APH

Repair & Replacement

of APH seal ducts and

expansion joints

67 689 0.328

Optimizing BFP

SEC, BFP pressure

drop optimization,

variable frequency

drive

implementation

BFP #4A cartridge was

replaced

Maintenance and

servicing of BFP

recirculation valve and

attending to valve passing

40

300

412

0.143

0.196

Optimization of

PA fan system and

APH area

Optimization and

modification of APH

60 617 0.294

MAIN PLANT AUXILIARIES AREA - 210 MW UNIT

Recommenda

tions

Plant side initiative Achieved

Reduction/

Saving

%

Savings

in APC

Amps KW

Improvement in

Condensate

extraction system

and optimization

of pump operation

2 nos. of CEP achieved

full load instead of 3 at

MCR after

implementation

22 201 0.096

Modification of

ARCW

requirements and

optimization of

CW system vis--

vis condenser

system

2 nos. of CW pumps

achieved designed

vacuum instead of 3 at

MCR prior to this study

1260 0.600

MAIN PLANT AUXILIARIES AREA - 210 MW UNIT

Recommenda

tions

Plant side initiative Achieved

Reduction/

Saving

%

Savings

in APC

Amps KW

Effective

improvement of

cooling tower

operation

8 nos. CT fans achieved

the desired results/

vacuum / temperature

instead of 10 nos. at MCR

prior to this study

280 181 0.086

TOTAL 1.743

MAIN PLANT AUXILIARIES AREA - 210 MW UNIT

OVERALL IMPROVEMENT SUMMARY 210 MW

PARAMETERS DURING THE

STUDY

AFTER

IMPLEMENTATI

ON OF THE

RECOMMENDA

TIONS

IMPROVEMEN

T ACHIEVED /

REMARKS

Average unit load

(MW)

165 200 30

PLF (%) 69 > 80% 17

Partial Loading (%) 21 5 16

APC (%) 11.6 9.857 1.743

Atemperation spray

(tons /hr.)

30 40 0 40

Combustible in fly

ash (%)

5 3 2

OVERALL IMPROVEMENT SUMMARY 210 MW

PARAMETERS DURING THE

STUDY

AFTER

IMPLEMENTATI

ON OF THE

RECOMMENDA

TIONS

IMPROVEMEN

T ACHIEVED /

REMARKS

Condenser Vacuum

(mm HG at MCR)

610 690 80

Specific steam

consumption

(T/MW)

3 2.83 0.17

GHG REDUCTIONS

Apart from Auxiliary power consumption and Heat Rate

Reduction which will be directly benefiting the Unit, there

will be additional benefit through Green House Gas Emission

Reduction and environmental improvement.

With Eastern Grid Emission factor of 1.025 Kg. /kWh saved

through energy conservation, the corresponding annual

Green House Gas Reduction for energy saving of 1.743% of

APC (ie, 2542775.55 Kwh) is 2606.34 Tons of CO2 emission

reduction annually.

CONCLUSION

Energy Efficiency offers significant potential for reduction of fossil fuel

consumption apart from environmental benefit, climate change impacts.

Some of the additional benefits by way of energy audit and energy

efficiency exercise lead to improvement in O&M and maintenance

practices as also PLF level of operating units.

Since capacity addition during 11th five year plan mainly through

thermal route, to meet increased consumption level (target of 1000

kWh/capita and growth rate 8 to 9%), mostly through fossil fuel route ,

state of the art energy efficient technologies, low carbon strategies, high

efficiency plants need to be addressed along with harnessing new and

renewable energy sources for power generation.

Apart from above, there will be ample opportunity for existing units

towards claiming CDM benefits.

Any Questions ?