Many problems in reciprocating compressors are caused by valve failures. Usually, valve failures are diagnosed early, and the worn out parts are replaced. This requires, however, unscheduled compressor shutdowns which increase the cost of operation and possibly breach gas delivery contracts. Thus, it is essential to design valves adequate for the particular compressors and flow conditions.
In this paper, it is determined that the cause of an unusually large number of valve failures at one of the NOVA Gas Transmission Limited (NGTL) compressor stations was an inadequate valve design. It is shown that the type of valve presently used is unacceptable and should be replaced. Due to economic restrictions, however, the existing valves are modified rather than replaced.
The method used to re-design the compressor valves includes two steps: field measurements and computer digital modelling. The modelling incorporates: i) acoustic simulation of the system, ii) compressor valve dynamic simulation, and iii) simultaneous simulation of fluid solid interactions between the compressor valves, compressor cylinders and pipework. The results obtained by using models ii) and iii) are compared.