Abstract: During the operation of a 1 million t/a ethylene plant in China, abnormal vibration fluctuations and gradual increase were observed at the high-pressure cylinder drive end of the cracking gas compressor, accompanied by an elevated leakage at the primary dry gas seal of the drive end. Through adjusting lube oil inlet pressure and temperature coupled with state monitoring and analysis, it was determined that the abnormal vibration at the drive end of the compressor's high-pressure cylinder was caused by the combined effects including the unstable condition of the bearing bushings on that side and disturbances caused by adjustment to the unit load. This abnormal phenomenon also indirectly affected the operation of the high-pressure cylinder drive-end dry gas seal, resulting in increased primary leakage flow. Aiming at the above reasons, online treatment measures such as increasing oil pressure, lowering oil temperature to improve oil film stiffness, and stabilizing compressor operating loads were taken to resolve the compressor abnormal vibration and meet the requirements for safe and stable production.

Key words: cracking gas compressorlunstable statelstate monitoring and analysisldry gas sealloil film stiffness