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ENERGY CONSERVATION

OPPORTUNITIES IN CHEMICAL

INDUSTRIESBy J P PATEL

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OBJECTIVE of this program is to understand how the energy is used in industries and what is the opportunities for energy conservations in industries.

We will focus on energy conservation opportunities and other ways to reduce energy consumptions in industries and buildings .

These training provide a source for quick savings energy in short time.

INTRODUCTION

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Energy auditAn evaluation of energy consumption, in a business, to determine ways in which energy can be conserved. Measure energy performance at a particular timeThree levels of audits carried out walk through, preliminary and detailedThis does not talk about policy objectives etc

This is purely technical measurement of energy and it its analysis over a periodEnergy audit is an input to energy review

Energy Audit

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1. Boiler, & Steam System – Thermal 2. Furnaces and hot oil heaters – Thermal 3. Compressed Air System – Electrical 4. HVAC and Chillers- Electrical 5. Pumping System – Electrical 6. Blowers & Fans - Electrical 7. Electric Motors – Electrical 8. Gen-Set – Thermal 9. Lighting – Electrical 10.Heat Exchangers – Thermal 11.Cooling Towers/Evaporative Cooling-

Thermal & electrical

Major Energy Consuming Assets

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The boiler and steam system are important equipment which has a significant impact on energy.

The main component of the boiler and steam systems

Burner (oil, gas, soil fuels like coal, biomass etc) Water treatment systems Boiler components like fire tube or water tube.

Burner Deaerators, super heaters, economizer, Airpreheater flue gas stack etc

Boilers, Burners and Steam System

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• The steam system components are:Steam pressure reducing stations, steam

pipe insulations, steam trap system, condensate piping.• The major losses in boiler are:1. Flue gas loss. (combustion loss)2. Heat transfer surface not clean.-scaling of

tubes . 3. The combustion is not proper . 4. Formation of CO Radiation losses from

boiler body.- inadequate insulation

Components of Steam system

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Poor combustion formation of CO and soot (carbon)

Heat transfer surface fouling Poor operating and maintenance Deteriorating fuel and water quality High flue gas temp. & more than required excess

air.

Heat balance: identify heat losses Boiler efficiency: determine deviation from best

efficiency

Causes of poor boiler performance

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• The major losses in the steam system are:1. The steam velocity(friction losses)2. The dryness fraction of the steam(effective

working of the steam trap)3. Saturated and condensing steam for heat

transfer purpose4. Steam leakage through pipes5. Insulation value, thickness6. These are to be controlled and audited regularly 7. Rain water ingress in insulation, the insulation

looses its effectiveness .

Steam systems

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1. Pipes –Optimum size, too high or too low size means energy loss .

2. Drain points – Leaking points . 3. Strainers & Filters – Chocked strainers loss of

energy 4. Separators – to separate condensate from steam 5. Steam traps – leaking and improper 6. Air vents – leakage, poor venting of air . 7. Condensate recovery system – efficient system

saves both water and energy. 8. Insulation – Optimum level of insulation .

Steam components

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1. Stack temperature control2. Feed water preheating using economizers3. Combustion air pre-heating4. Incomplete combustion minimization5. Excess air control ( 5% for gas , 10% for

liquid fuels and 15 to 20% for solid fuels ) . Can be achieved on online oxygen analysis with controller on air to burner .

6. Avoid radiation and convection heat loss

Boiler energy saving opportunities

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7. Automatic blow down control8. Reduction of scaling and soot losses9. Reduction of boiler steam pressure10.Variable speed control for boiler feed water

pump. 11.Controlling boiler loading12.Proper boiler scheduling for batch process

requirements .

Boiler energy saving opportunities

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Steam should be available: In correct quantity At correct temperature –NO superheated

steam for heat transfer through condensation

Free from air and incondensable gases Clean (no scale/dirt) Dryness fraction should be > 95%

Steam quality

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Compressor is one the major energy consuming equipment and it is very important to control the same.Compressed Air is costliest form of energy. • Compressed air system consists Air compressor Piping and valves• The compressors main types1. Reciprocating type ( least efficient ) 2. Screw type3. Centrifugal type ( most efficient )

The efficiency of each type varies and also capacity limitations(for centrifugal)

Compressed air systems

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To improve the efficiency select screw type compressor for small medium applications.

For large application select centrifugal type which is the most efficient.

However due the fact that cost of application point of view the compressor selected.

Compressed air system(Cont.)

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The efficient use of the compressor depends on how efficiently compressed air is used.

In order to select right compressor use dedicated compressor for different pressure rather than throttling and reducing the pressure(losses of energy).• The other losses are from piping system

are two types:1. Frictional losses2. Leakages

Operation of the compressors

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The other possible saving can be replacing the air operated valves with electrical operated.

Dirty filter(clean filter regularly). Loading-unloading cycles to be adjusted

carefully. Reduction in discharge pressure of

compressor Take a leakage test of compressed air

system and reduce the leakages. (Air leakage is a waste of energy which is invisible)

Operation of the compressors

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Ensure air intake to compressor is not warm and humid by locating compressor in well-ventilated area.

Minimize low-load compressor operation. Periodic cleaning of inter-coolers must be

ensured. Compressor free air delivery(FAD) test to check

the present operating capacity/design Use multi-stage compressor as it consumes

less power for the same air output than a single stage compressor.

Checklist for energy efficiency in compressed air system

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Keep the minimum possible range between load and unload pressure settings.

Reduce compressor delivery pressure, wherever possible, to save energy.

Carry out periodic leak tests to estimate the quantity of leakage of compressed air.

Install equipment interlocked solenoid cut-off valves in the air system so that air supply to a machine can be switched off when not in use.

Check air compressor logs regularly for abnormal readings.

Checklist for energy efficiency in compressed air system (Cont.)

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HVAC is heating ventilation and air conditioning.

Ventilation system are used for fresh air circulation.

Air conditioning systems are used mainly as comfort purpose to cool the air .

Chillers are used for process cooling/chilling.

The ventilation systems is mainly fans and ducting.

HVAC and CHILLERS

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• Air conditioning systems are many types: Window Window split Packaged type Central air conditionThe window and split AC are individual control. The energy savings is mainly through

setting of temperature. However if it is used for the process such as PLC control etc. The requirement may be different

AIR CONDITIONING SYSTEMS

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• The central air condition systems are 2 types:1.Direct expansion compressed2.Chilled water system(by generating chilled

water and indirect cooling) The energy saving is achieved by selecting the

right type of compressor and controlling the air handling units(ducting and blowers)

The temperature control can be achieved by sensors and thermostats

The energy saving can be achieved by higher setting of temperature and preventing leakage of cool air. Better insulation also helps to save energy on air conditioning.

CENTRAL AIR CONDITION

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Use water-cooled chillers rather than air-cooled chiller.

Avoid over sizing- match the connected load. Optimize condenser water flow rate and

refrigerated water flow rate. Improve control and utilization of outside air. Clean HVAC filters, unit coils on a schedule. Seal leaky HVAC ductwork and leaks around

coils. Establish an HVAC efficiency-maintenance

program for better efficiency.

Energy saving opportunities

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Pumps are used for transferring fluids like water, liquids etc from lower to higher level called Head.

Various types of pumps used like centrifugal, reciprocating, rotary etc. are use

The majority of pumps are centrifugal and focus may on the centrifugal.

PUMPING SYSTEMS

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The system consist of pumps and piping and valves.

Like all fluid handling system the throttling of pumps to be avoided as far as possible. The throttling action gives lot of pressure drop and hence the power.

Also piping systems involves lot of friction loss.

Pumping system(cont.)

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Pump shaft power (Ps) is actual horsepower delivered to the pump shaft:

Pump shaft power (Ps)= Hydraulic power HP/ pump efficiency

Pump efficiency = Hydraulic power/pump shaft power

Pump output/Hydraulic/Water horsepower is the liquid horse power delivered by the pump.

Pump power

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1. Selecting the right pump2. Controlling the flow rate by speed variation

(VFD)3. Pumps in parallel to meet varying demand4. Eliminating flow control valve5. Eliminating by-pass control6. Start/stop control of pump7. Impeller trimming

ENERGY SAVING OPPORTUNITIES

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Blowers and fans are similar to pumps but handles compressible fluid such air.• Fans and blowers are two type mainly used1. Centrifugal 2. Axial The power consumption and characteristic

curves given by the supplier. Select the performance at the best efficiency

point Estimate correct pressure drop across the

system It is always better to modify the ducting

system rather than throttling.

BLOWERS AND FANS

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Sum of static pressure losses in system:

1.Configuration of ducts, pickups, elbows2.Pressure drop across equipment

• Increases with square of air volume Long narrow ducts, many bends: more

resistance Large ducts, few bends: less resistance

System losses

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1. Choose the right fan2. Reduce the system resistance3. Operate close to BEP (best efficiency point) 4. Maintain fans regularly5. Control the fan air flow Properly lubricated precision spur gears 98%

for each step Flat belt drive 97% - Power transmission loss

3% V-belt drive 95% Transmission loss is 5%

ENERGY SAVING for FANS

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Motors are the prime movers in many industries.

Motors are used to run the machinery and other systems like water pumping, air moving in fans, blowers and compressors.

The major consumption of electric power is the motors in many industries.

Therefore more attention may be given to the motors and its efficient use.

ELECTRIC MOTORS AND DRIVES

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In general motors are classified with their efficiency like high efficient motors.

The motors of NEMA standards are the highest efficiency. (90% and above)

The motor efficiency depend on the load of the motors(less than 50% load is highly inefficient). Motor manufacturers give efficiency at full load.

Rewind motors looses the efficiency due to poor winding and the winding losses are more . Motor efficiency goes down by 1 to 1.5%.

Energy savings in motors

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The motors are fitted to machines through various transmission devices.

These are direct mounting on the motor shaft through coupling. The transmission losses is around 5%.

Through belts and pulleys properly maintained and the selection belts can save up to 3% of power.

Drives

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The electrical systems consist of incoming transformers, bus bars, cabling and internal distribution through MCC’s.

The power may be obtained from grid or by Diesel gen-set or by both.

The energy saving is by maintenance of power factor(Lagging).

The power can be saved by selecting right size cables which can minimize the I2 R losses. Proper cable connection can also reduce the loss.

Electrical systems and Gen-sets

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Lighting account for 5-10% of the electrical energy consumed in the industries and 30 to 40 % in commercial buildings and malls .

The lighting system are used for general lighting.

Task lighting Street and security lighting

Lighting systems

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• The lights are many types: Incandescent – Highly inefficient Fluorescent – tubes T-10 & T-12 , & T-5 Compact fluorescent(CFL) Metal halide Halogen Mercury vapor High pressure sodium vapor LED Induction LED and T-5 are most energy efficient

and long lasting .

Lighting system

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• The energy conservation methods Use dimmer wherever possible Change the chokes magnetic (15 w) to

electronic chokes (1w) Replace T8 tube with T5 or with LED Replace CFL with LED . Use of Natural lights by transparent plastic

roof sheets LED and Induction light can be considered

after all above modification

Lighting systems(Cont.)

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Energy performance indicators ENPI It is defined as ratio energy consumed over a

defined period to the output or as defined by the company

Base lines are the bench mark derived from statistical method either average or regression or by cusum methods.

The base lines are adjusted as per the changes ENPI due the variable such as operating condition

ENPI and Baseline

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Electrical measuring instruments- power analyzer.

Combustion analyzer Manometers Thermometers – infra red (Non Contact Type) Water flow meters – Ultrasonic flow meter Speed measurement –Tacho meters Leak detectors Lux meters – for light intensity

measurement.

Measuring Equipments

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Lighting – LED and Induction lighting Solar Thermal- like vacuum evacuated tube,

Fresnel collectors for higher temperature. Absorption chillers Heat of compression drying(air

compressors) Dry type transformers Biogas from sewage and bio-waste

New and Emerging Technologies

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HEAT EXHANGERS

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Heat exchangers performance measurement

Tube cleaning periodically based on performance

Use of heat exchanger as Economiser by pinch technology

Less opportunities for energy saving as compared to other machineries.

ENERGY SAVING OPPORTUNITIES IN HEAT EXCHANGERS

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COOLING TOWERS

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Cooling tower fans made of FRP blades are aerodynamic in profile to meet specific duty conditions more efficiently.

Due to light weight FRP fans need low starting torque resulting in use of lower HP motors.

Proper gas liquid contact leads to better mass transfer/Evaporative cooling

ENERGY saving opportunities in COOLING TOWERS

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Implementation

energy conservations and also efficiency of the equipment is necessary.

Therefore the organization can think of performing energy audit EnMS system implementation will lead to

excellence in energy saving and sustainability.

Conclusion

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Thank You