Abstract: Polyolefin plant is the main unit of benefit output in certain petrochemical company. The operation state of circulating gas compressor determines the stability rate of the plant, which directly affects the completion of annual benefit index of the petrochemical company. The vibration of the bearing bush on the motor coupling side of the Japanese Kobe DH9M circulating gas compressor was always on the high side after the device was shut down for maintenance. During this period, it was treated for many times in the window period, but the effect was not obvious. During one year's operation, the vibration fluctuation frequency and amplitude increased and reached the alarm value for many times. The SG8000 online monitoring system is used to analyze and diagnose the fault causes. The causes of the fault was analyzed and diagnosed through the SG8000 online monitoring system. And the results showed that it was caused by the soft rubbing at the motor drive end. This diagnosis was verified during the overhaul. After shutdown for implementation of treatment measures, the unit ran smoothly and the vibration fault was fundamentally solved.

Key words: recycle gas compressor, condition monitoring, vibration wave, fault diagnosis