Abnormal High-Temperature Behavior Troubleshooting of Process Compressor Tilting Pad Journal Bearing

A DE-side LBP tilting pad journal bearing of a 1-stage overhung heat-pump compressor in a propylene process exhibited abnormal high-temperature behavior. Its temperature had been relatively high at 78∘C from the beginning of operation. In 2014, after three years of operation, it increased suddenly and reached 103∘C . Installing a varnish removal equipment and others managed to stabilize the temperature at 95∘C . We undertook a troubleshooting approach for reviewing the comprehensive status and integrity of the temperature design of the bearing. We performed lubrication and heat-balance analysis, based on the design engineering data and documents supplied by the OEM. For the base design data of DE-side TPJB, evaluating the effects of key design variables on bearing metal temperature showed that firstly, increasing the bearing clearance and supply oil flow-rate, and next, changing the oil type, and finally, increasing the machined pad clearance and offset, are more effective in reducing the bearing metal temperature. Furthermore, a clarification meeting with the OEM revealed that an incorrect decision had been made to decrease the bearing clearance to eliminate the SSV harshness issue, while not maintaining a sufficient oil flow-rate. We conducted a detailed retrofit design analysis, wherein we increased the oil flow-rate and bearing clearance by decreasing the preload. We predicted that the bearing temperature would decrease to 63∘C from 75.7∘C even at the rerate condition. Finally, after installing and operating a retrofit replacement bearing in 2015, the bearing temperature stabilized at a low temperature of 65∘C . Currently (January. 2017), two year later, the bearing metal temperature remains at 65∘C . Therefore, we can conclude that the abnormal high-temperature behavior of the bearing has been resolved completely.