RULES FOR SAVING ELECTRICITY
- Undertake regular energy audits.
- The maintenance in plant should follow the "zero leak" philosophy, particularly in the areas of steam and utilities so that loss of energy could be totally eliminated.
- Plug all oil leakage. Leakage of one drop of oil per second amounts to a loss of over 2,000 litres/ year.
- Filter oil in stages. Impurities in oil affect combustion.
- Pre-heat the oil. For proper combustion, oil should be at right viscosity at the burner tip. Provide heat capacity.
- Incomplete combustion leads to wastage of fuel. Observe the colour of smoke emitted from chimney. Black smoke indicates improper combustion and fuel wastage. White smoke indicates excess air and hence, loss of heat. Hazy brown smoke indicates proper combustion.
- Use of low air pressure "Film Burners" helps save oil up to 15% in furnaces.
FURNACE
- Recover and Utilise waste heat from furnace fuel gases for preheating of combustion air. Every 21°C rise in combustion air temperature results in 1% fuel oil savings.
- Control excess air in furnaces. A 10% drop in excess air amounts to 1% saving of fuel in furnaces. For an annual consumption of 3,000 litres of furnace oil means a saving of Rs. 3 lakh (assuming the cost of furnace oil is Rs. 10 per litre).
- Reduce heat losses through furnace openings. Observation shows that a furnace operating at a temperature of 1,000 °C having an open door results in a fuel loss of 10 litres/hour. For a 4,000 hour furnace operation, this translates into a loss of approximately Rs. 4 lakh per year.
- Improve insulation if the surface temperature exceeds 20°C above ambient. Studies have revealed that heat loss from a furnace wall 115 mm thick at 650°C amounting to 2650 Kcal/m² /hr can be cut down to 850 kcal/m²/hr by using 65mm thick insulation on the 115 mm wall.
- Proper design of lids of melting furnaces and training of operators to close lids helps reduce losses by 10% to 20% in foundries.
BOILER
- All possible attention should be paid to control excess air by monitoring oxygen level in fuel gas and also by visual inspection of flame colour.
- Use only treated water in boilers. A scale formation of 1mm thickness on the waterside would increase fuel consumption by 5% to 8%.
- Remove soot deposits when fuel gas temperature rises 40°C above the normal. A coating of 3mm thick soot on the heat transfer surface can cause an increase in fuel consumption of as much as 2.5%.
- Recover heat from steam condensate. For every 6°C rise in boiler feed water temperature through condensate return, there is a 1% saving in fuel.
- Soot blowers can always be maintained in perfect working condition so that their regular and periodic use does not suffer.
- Improve boiler efficiency. Boilers should be monitored for fuel gas losses, radiation losses, incomplete combustion, blow down losses, excess air etc.
- Proper control can decrease consumption up to 20%.
- Stop steam leakage. Steam leakage from a 3mm-diameter hole on a pipeline carrying steam at 7 kg/cm² would waste 32 kilolitres of fuel oil per year amounts to a loss of Rs. 3 lakh.
COMPRESSED AIR
- Compressed air is very energy intensive. Only 5% of electrical energy is converted to useful energy. Use of compressed air for cleaning is rarely justified.
- Increase in inlet air temperature by 3°C increases power consumption by 1%. Ensure low temperature of inlet air.
- Reduction in discharge pressure by 10% saves energy consumption up to 5%. It should be examined whether air at lower pressure can be used in the process.
- Air output of compressors per unit of electricity input must be measured at regular intervals. Efficiency of compressors tends to deteriorate with time.
REFRIGERATION AND AIR CONDITIONING
- Doors and windows should remain closed while the air conditioner is running. Moreover, ceiling fans should be used instead of house or window fans while the air conditioner is on.
- 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.
- Maintain condensers for proper heat exchange. A 5°C decrease in evaporator temperature increases specific power consumption by 15%.
- Utilisation of air conditioned/refrigerated space should be examined and efforts made to reduce cooling load as far as possible.
- Utilise waste heat of excess steam or fuel gases to change over from gas compression systems to absorption chilling systems and save energy costs in the range of 50% to 70%.
- The compressor of the central air conditioner should be located in a cool, shaded place outside.
- Specific power consumption of compressors should be measured at regular intervals. The most efficient compressors should be used for continuous duty, while other are kept on a standby.
- The air conditioning unit must be inspected; cleaned and tuned by a professional every two to three years to keep it going longer and consume less electricity. If the refrigerant needs to be recharged, make sure it is done correctly. If it is overcharged, it would reduce operating efficiency and could damage the unit. If it is undercharged it would consume energy less efficiently.
- The duct system should be properly sealed. This could save 10% to 15% of the electricity into air conditioner.
MOTORS
- The motors should be energy efficient.
- Install soft start-cum-energy saver for lightly loaded motors.
- In case of centrifugal blower pump, install variable voltage frequency drives for speed control of motors.
- Install multi speed motor.
- Optimize operating voltage level of motor for lightly loaded motors.
- Provide interlock for electric motor to avoid idle running.
- Replace motor generating sets with thruster drives.
- Avoid frequent rewinding of motors. Greater the number of rewind, lesser the efficiency.
- Carry out preventive maintenance and condition monitoring schedule regularly. Advantages of Energy Efficient Motors.
- Reduced operating costs.
- Less heat losses.
- Extended winding lifespan.
- Extended lubricating grease service life.
- Lower noise levels than other motors.
- Reduced energy costs. The higher purchase price investment pays off.
- Reduce emission of CO2 and NOx greenhouse gasses from power stations for positive environmental effect.
COOLING TOWERS
- Replacement of inefficient aluminium or fabricated steel fans with molded FRP fans with aerofoil designs results in electricity savings in the range of 15% to 40%.
- 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% to 0.02% with a fan power energy saving of 10%.
- Install automatic ON-OFF switches on cooling tower fans and save up to 40% on electricity costs.
- Use of PVC fills in place of wooden bars results in a saving in pumping power of up to 20%.
