Tips For Energy Conservation In Industrial Sector

TIPS FOR ENERGY CONSERVATION IN INDUSTRIAL SECTOR By, NAGARAJAN.S Manager M&O MacLellan India

• BOILERS : • 1. Increasing the steam output / Kg of fuel burnt through improved efficiency, by way of avoiding heat loss encountered through insulation and refracting, improves boiler efficiency from 20% to 80%. • 2. Install economizer in Boiler for preheating feed water wherein the temperature is raised from 70 Degrees to 120 Degrees. This results in 3% saving in fuel. • 3. Improve the efficiency of boiler by soot blowing and controlling excess air. This results in 2% increase in boiler efficiency. • 4. Using treated water in boilers, avoids scale formation resulting in decrease in fuel consumption by five percent to eight percent. •

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• BOILERS : • 5. Installing air pre-heater to the boiler enhances effectiveness of combustion of oil by aiding atomization. • 6. Convert grate fired boiler into fluidized bed boiler for improving efficiency. • 7. Usage of fuel oil additive for LSHS. 8. Reducing the blow down frequency of feed water avoids loss. • 9. Arresting steam leakage in the pipelines. • 10. Recover heat from steam condensate. • 11. All possible attention should be paid to control excess air by monitoring oxygen level in flue gas and also by visual inspection of flame color.

FURNACE: • 1. Improvement in furnace efficiency can be achieved by using optimum excess air and reduction of radiation loss by application of insulation bricks or increasing the wall thickness. • 2. Improve insulation if the surface temperature exceeds 20 degrees above ambient. • 3. Minimize the heat loss through the exhaust fans and opening at the entrance and exit. • 4. Replace the control panels of resistance heating ovens and furnaces by thyristor control panel. • 5. Proper design of lids of melting furnaces and training of operators to close lids helps reduce losses by 10-20% in foundries. • 6. Recover and utilize waste heat from furnace flue gases for preheating of combustion air. Every 21degree Centigrade rise in combustion air temperature results in one percent fuel oil savings.

COMPRESSED AIR: • 1. Reduce the temperature inside the compressor house by providing bigger windows and openings in the compressor room or extend suction pipe to outside the building. • 2. Replace absorption type air dryers with refrigeration type dryers. • 3. Arresting of air leakage at air receivers, relief valves, pipes and house shut off valves, quick relief couplings, tools and equipments of the compressed air system. • 4. Avoid usage of compressed air for purposes for which compressed air is not a necessity. Use blowers for removing the water from chill rolls. 5. Replace single stage compressors with double stage compressors

PUMPS: • Improper selection of pumps can lead to large wastage of energy. A pump with 85% efficiency at rated flow may have only 65% efficiency at half the flow. Select a pump of the right capacity in accordance with the requirement. • Use of throttling valves instead of variable speed drives to change flow of fluids is a wasteful practice. Throttling can cause wastage of power to the tune of 50 to 60%. • Drive transmission between pumps & motors is very important. Loose belts can cause energy loss unto 15-20%. Use efficient transmission system. Maintain right tension and alignment of transmission belts. • Modern synthetic flat belts in place of conventional V belts can save 5% to 10% of energy. • Matching of the motor with the appropriate-sized pump is essential. Cont……

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PUMPS:

• It is advisable to use a number of pumps in series and parallel to cope with variations in operating conditions by switching on or off pumps rather than running one large pump with partial load. • Proper installation of the pump system, including shaft alignment, coupling of motor and pump is a must. • Properly organized maintenance is very important. Efficiency of worn out pumps can drop by 10 per cent to 15 per cent, unless maintained properly. •

Periodically check pump system and carry out corrective measures such as lubrication, alignment, tuning of engines and replacement of worn-out parts.

MOTORS • 1. The motors should be energy efficient. • 2. Convert delta to star connection for lightly loaded motors. • 3. Install soft start-cum-energy saver for lightly loaded motors. • 4. In case of centrifugal blower pump, install variable voltage frequency (VFD) drives for speed control of motors. • 5. Replace eddy current controls / fluid coupling drives with variable frequency drives for varying speed driven equipment. • 6. Provide interlock for electric motor to avoid idle running. • 7. Avoid frequent rewinding of motors. Greater the number of rewind, lesser the efficiency. • 8. Replace metal cooling fans of motors with FRP blades. • 9. Replace V-belt drives by flat belt drives. • 10. Carry out preventive maintenance and condition monitoring

Advantages of Energy Efficient Motors • 1. Reduced operating costs. • 2. Less heat losses. • 3. Extended winding lifespan. Extended lubricating grease service life. • 4. Lower noise levels than other motors. • 5. Reduced energy costs. The higher purchase price investment pays off. • 6. Reduction in green house gas emissions resulting from reduced energy consumption.

COOLING TOWERS • 1. Replacement of inefficient aluminum or fabricated steel fans with molded FRP fans with aerofoil designs results in electricity savings in the range of 15 percent to 40 per cent. • 2. A study on a typical 20 feet diameter fan revealed that replacing the wooden blade drift eliminators with newly developed cellular PVC drift eliminators reduces the drift losses from 0.01 per cent to 0.02 per cent with a fan power energy saving of 10 per cent. • 3. Install automatic ON-OFF switches on cooling tower fans and save up to 40 per cent on electricity costs • 4. Centralize utilities by providing a common chilled water line, chilled brine line, cooling water line and compressed air line. • 5. Reduce scaling in cooling towers by adopting proper water quality management.

REFRIGERATION & AIR CONDITIONING • 1. Use of double doors, automatic door closures, air curtains, double glazed windows, polyester sun films etc. reduces heat ingress and air-conditioning load of buildings.

• 2. Maintain condensers for proper heat exchange. A 5°C decrease in evaporator temperature increases specific power consumption by 15%.

• 3. Utilization of air conditioned/ refrigerated space should be examined and efforts made to reduce cooling load as far as possible. • 4. Utilize waste heat of excess steam or flue gases to change over from gas compression systems to absorption chilling systems and save energy costs in the range of 50-70%. • 5. Specific power consumption of compressors should be measured at regular intervals. The most efficient compressors to be used for continuous duty and others on standby.

DG SETS

• 1. A poorly maintained injection pump, faulty nozzle increases fuel consumption. • 2. Blocked filters increase fuel consumption. • 3. Measure fuel consumption per kWh of electricity generated regularly. Take corrective action in case this shows a rising trend.