A Comparative Study of Performance and Efficiency of High-Speed Compressor Valves
Reciprocating compressor efficiency is heavily dependent the performance of the suction and discharge compressor valves. Performance and endurance tests in the past have been conducted to explore the performance of several types of compressor valves. The majority of these studies have been conducted on slow speed reciprocating compressors; therefore, a need exists for an updated study on higher speed, variable frequency compressors. A variable speed reciprocating compressor unit has been selected by El Paso Pipeline Groups Plant Services department to conduct a performance and endurance test on six compressor valves from five OEM and aftermarket valve manufacturers. The valves tested were two plate type valves and four poppet valves. The compressor valves were tested over a compression ratio of 1.15 to 1.30 for 3000 unit operating hours. The compressor efficiencies, calculated using the Benedict-Webb- Rubin (BWR) equation of state, ranged from 65% at a compression ratio of 1.15 to 82% at 1.28. Efficiency data was supplemented with pressure-volume cards captured using a multi-channel data acquisition system. The data shows that percent valve loss, at a rated horsepower and speed of 1000 RPM, varied from 16% at a compression ratio of 1.28 to 29% at 1.19. At a minimum speed of 800 RPM, valve loss varied from 12% at a compression ratio of 1.28 to 19% at 1.19. Results of the performance and endurance test will be presented without disclosing the valve manufacturer, but will demonstrate that valve selection can have a significant impact on overall compressor efficiency. The valve manufacturers who allowed their valves to be analyzed will be notified of which data corresponds to their valve make, allowing them to assess their relative performance among the group.