Optimization of Single-unit Compressed Air Systems

Abstract

ABSTRACT Commercial and industrial customers are switching from reciprocating to rotary screw compressors for small, single-compressor systems (under 50 hp). Systems of this size represent a majority of the compressed air market in terms of numbers. Rotary screw compressors do not have the same energy profile as reciprocating compressors, making them significantly less efficient at part loads if installed in a standard manner. Because most compressed air systems operate at partial loads most of the time, significant savings of 50–80% can be gained if energy efficiency optimization measures are applied. Although the full-load efficiency of a rotary screw compressor is normally higher than a two-stage reciprocating compressor, contrary to popular belief the rotary screw is much less efficient at part load if running in modulation or load/unload operating mode. Four modes of compressor operation are possible for small rotary screw compressors, with modulation mode and load/unload mode shown to be much less e...