$396,842 per year in energy savings was achieved by installing inlet suction valve controls on their fuel gas compressors. The electric utility assisted with a $326,000 Energy Efficiency Incentive.
The Southern California refinery used one 700 HP and three 350 HP reciprocating compressors to digest waste fuel gas and process it in to a version usable by their Co-Generation Plant. This system demanded 1,039 kW on average and consumed 9,036,477 kWh per year. The baseline compressor controls were two stage thus more product then necessary was always compressed. This wastes energy as compressed gas has to "spillback" upstream of the compressors in order to keep the units operating at one of their two capacity set-points; then the gas needs to get compressed again.
It was recommended that compressor controls be installed in order to prevent this "spillback" by enabling infinite operating set-points. During production periods outside of the original two compressor stages, the proposed controls allow the compressors to operate at whatever flow required in order to compress only what is necessary, thus minimizing the energy consumed.
Based on the average operating set-points, the automatic compressor controls reduced demand by 423 kW and is saving 3,698,426 kWh ($396,842) per year.