Manufacturers Best Practice Guide
Compressed Air: Tips for Energy Savings
Actions to improve the efficiency of compressed air systems:
- Incorporate air compressors into an overall energy management plan.
- Perform an audit and benchmark air compressor use.
- Check compressor pressure. The compressor must produce air at a pressure high enough to overcome pressure losses in the supply system and still meet the minimum operating pressure of the end use equipment. Every two pounds-per-square-inch decrease in compressor pressure will reduce your operating costs 1.5%.
- Verify appropriateness of compressor size for end uses. Match loads. If your compressor is oversized, add a smaller compressor and sequence controls to make its operation more efficient when partially loaded. Sequence controls can regulate a number of compressors to match compressed air needs as they vary throughout the day. Line size should also be taken into consideration when updating your systems.
- Optimize distribution systems operations. Identify air storage capacity, pressure drop, air leaks and condensation drains. Leaks can result in up to 20% to 30% in wasted energy. Repairing leaks also reduces compressor use time, and therefore, electricity use. Inadequate drainage can increase pressure drops across the distribution system.
- Identify artificial demands and use pressure regulators at the end use to minimize artificial demand. Artificial demand is created when an end use is supplied air pressure higher than required for the application. If an application requires 50 psi but is supplied 90 psi, excess compressed air is used.
- Limit the use of compressed air and disconnect the compressed air source from unused equipment. Over 80 percent of the electricity used for this process is attributed to wasted heat at the compressor. Use alternatives to compressed air when possible: air conditioning or fans to cool electrical cabinets and blowers for agitating, cooling, mixing and inflation of packaging. Also try using low-pressure air for blowguns and air lances.
- Improve routine maintenance. Change air filters regularly and routinely check the compressor's v-belts for proper tightness. Loose belts slip more frequently and reduce compressor efficiency.
- Employ a heat recovery system. As much as 80% to 90% of the electrical energy used by an air compressor is converted to heat. A properly designed heat recovery unit can recover 50% to 90% of this heat for heating air or water.
- Maintain inlet air filters to prevent dirt from restricting airflow to the compressor and causing pressure drops. Retrofit the compressor with large-area air intake filters to help reduce pressure drop.
- Add an air receiver/surge tank to buffer short-term demand changes and reduce on/off cycling of the compressor.
- Utilize cooler intake air, which is denser. Compressors use more energy as intake air temperature increases. Cooler air is denser and provides more mass for each compression cycle with no additional power use. Use outside air for cooling reciprocating and lubricant-free screw compressors when it is cooler than indoor air.