Compressed air systems are employed in virtually all manufacturing plants, including automotive industries, and compressed air systems can account for five to twenty percent of plant energy consumption. Therefore, exploring opportunities to decrease the energy consumption of this equipment can result in significant energy and cost savings, resulting in more energy efficient automotive plants.
In this paper, a case study for a 360,000 square-foot automotive interiors plant operated by Johnson Controls andlocated in Alabama, United States is considered. The plant uses two 150 horsepower rotary screw compressors which deliver an average of 800 cubic feet per minute with an energy usage of 1,414,000 kWh per year.
A compressed air system analysis was performed at this plant using the Department of Energy (DOE) software tool AIRMaster. Energy usage was determined by measuring the current draw from the air compressors using data loggers over a period of two weeks. From the collected data, AIRMaster was used to baseline the energy consumption of the system. The tool was then used to investigate recommendations to increase the efficiency of the system.
The plant implemented the recommendation to reduce plant air pressure by installing a flow controller. By incrementally reducing pressure and monitoring plant production, system pressure was reduced from 125 psi to 95 psi. Also, compressor discharge pressure was reduced from 125 psi to 114 psi.
Following the pressure reduction program, data loggers were used to measure compressor performance and verify savings. Net savings of over $25,000/yr were determined.