INTERNAL HYSTERESIS EXPERIENCED ON A HIGH PRESSURE SYN GAS COMPRESSOR

摘要

This paper describes a vibration instability phenomenon experienced in operating high pressure syn gas centrifugal compressors in two Ammonia plants at Qatar Fertiliser Company. The compressors were closely monitored using orbit and spectrum analysis to follow up changes from baseline readings. Tape recordings of run up and run down data presented a clue to the cause of the instability, which was later confirmed through physical examination of the rotor assembly. Internal hysteresis was the major destabilizing force. However, the problem was further complicated by seal lock-up at the suction end of the compressor. Also, a coupling lock-up problem and a coupling fit problem, which caused frettage of the shaft, should not be counted out as contributors to the self-excited vibrations.