Investigation and Analysis of High Thrust Bearing Temperature After Field Overhaul and Rerate of a Centrifugal Compressor

Case StudyA centrifugal compressor in olefins plant charge gas service experienced excessive thrust bearing temperatures after startup following a field overhaul and rerate. While the machine was online, an analytical study was carried out to determine the possible causes for the excessive thrust bearing temperature. The study involved confirmation of the aero load through calculation, verifying the thrust bearing’s capacity with the use of computer modeling, and correlation with operating field data to determine the likely cause of thrust bearing distress. A mechanical test of an identical spare bearing was conducted on an existing thrust bearing test rig to confirm the results of the analytical study and field observations. A compressor outage was ultimately required to remedy the thrust bearing issue. A methodical approach to the shutdown work was employed to assure detection and correction of the cause for the thrust bearing distress while minimizing the duration of the plant outage. The approach included full scale oil flow rate testing in the field as well as a comprehensive bearing disassembly and inspection plan. The culprit for the excessive thrust bearing temperature was discovered and corrected allowing for successful compressor operation after restart. This case study examines non-intrusive analysis and test methods to understand the issue without the chance of repeated outages