Performance & Endurance Tests of Six Compressor Valves in Mainline Natural Gas Compression Service
Performance and endurance tests were conducted on six different compressor valves from five major OEM and aftermarket valve manufacturers. The six valves tested included two ring-type valves, three standard poppet valves and one small poppet valve. The valves were tested for reliability and endurance over a period of six months in a mainline compressor station environment. All tests were conducted with an overriding emphasis on accuracy and fairness in every phase of testing and reporting. Valve performance was measured at the start and end of the 6-month test period using the same gas compressor cylinder and similar compressor operating conditions. All valves operated reliably over the 6-month test period. The valves were tested from compression ratios of 1.1 to 2.0. The testing was designed to isolate valve performance and to exclude the effects of compressor cylinder passages. Valve efficiencies were calculated using the BWR equation of state and supplemented with pressure volume data from a state-of-the-art Windrock 6310 performance analyzer. Peak valve efficiencies were related to the compression ratio, and the maximum efficiencies of 86-88% were found at compression ratios above 1.3. Below a ratio of 1.3, the efficiencies declined until they dipped into the 60s at a ration of 1.1. The pressure volume traces correlated reduced efficiencies to increased valve losses. The losses were greatest at low compression ratios and high flows. Most compressor valves had similar efficiencies within 1% of each other under similar operating conditions. Once valve was 2-6% less efficient than the other valves. Valve efficiency, reliability and cost of operation are presented, compared and discussed in detail.