List of energy efficiency opportunities in air compressors

Compressor Sankey Diagram

Compressed air is one among the costliest utility in any industry. If you see the above diagram for 100% electrical input energy only around 10%  will be a useful output. Just this number is enough to recognize how valuable is this utility. Apart from measuring and monitoring air compressor efficiency, it is of equal importance to ensure the entire compressor system run efficiently. Below is the list of some energy efficiency opportunities in compressed air systems 

• Install a control system to coordinate multiple air compressors and run in master-slave mode when and where applicable.
• Study part-load air compressor efficiencies and cycling costs to determine the most efficient mode for operating multiple air compressors
• Replacing old pipelines with low friction low weight Aluminium pipes.
• Avoid oversizing - match the connected load.
• Load up modulation-controlled air compressors. (They use almost as much power partial load as at full load)
• Turn off the back-up air compressor until it is needed.
• Reduce air compressor discharge pressure to the lowest acceptable setting. (Reduction of 1 kg/cm air pressure (8 kg/cm to 7 kg/cm') would result in savings of around 9% in compressor power consumption. This will also reduce compressed air leakage rates by 10%)
• Use the highest reasonable dryer dew point settings after assessing the climate conditions at the site.
• Turn off refrigerated and heated air dryer when the air compressors are off to save standby compressor power consumption.
• Use solenoid valves for compressor cooling water line and operate only when the compressors are running. 
• Use a control system to minimize heatless desiccant dryer purging.
• Minimize purges, leaks, excessive pressure drops, and condensation accumulation (Compressed air leak from 1 mm hole size at 7 kg/cm pressure would mean power loss equivalent to 0.5 kW)
• Use level based drain controls instead of continuous /timer air bleeds through the drains.
• Consider engine-driven or steam-driven air compression to reduce electrical demand charges
• Replace standard -belts with high-efficiency flat belts as the old v-belts wear out. (Increases air compressor efficiency by about 3 - 5% )
• Use a small air compressor when a major production load is off
• Take air compressor intake air from the coolest (but not air-conditioned) location (Every 5 Degree C reduction in intake air temperature would result in 1 % reduction in compressor power consumption)
• Use an air-cooled aftercooler to heat building makeup air in winter
• Be sure that heat exchangers are not fouled (e.g.. with oil).
• Monitor pressure drops across suction and discharge filters and replaces when and where the pressure drops are high.
• Use a property size compressed air storage receiver
• Consider using blowers instead of compressed air for cleaning and cooling applications
• Consider using electric tools instead of pneumatic tools since the cost of electricity is relatively lesser than compressed air.
• Use transvector air nozzles for cleaning instead of compressed air and reduce the compressor air usage by almost 50%
• Regularly conduct leakage test by pump up method and resolve leakage issues.
• Use IFC controllers and get rid of losses due to fluctuating loads
• Install compressor low-grade waste heat recovery system in case any use of hot water is required in the facility. You can obtain hot water with temperatures up to Element temperature -15 Degree Centigrade.
• Buy energy-efficient compressor by design.  
• Check for installation of VFD in case of high unloading percentages. Take care of the oil circuit before installing VFD.
• IE4 motor embedded air compressor efficiencies are superior compared to conventional motors.