Experience In The Use Of Flexure Pivot Tilt Pad Bearings In Boiler Feed Water Pumps

Abstract

Boiler feedwater (BFW) pumps are among the most critical rotating equipment in power plants. The bearings in these pumps must be able to attenuate rotor vibrations and other hydraulic forces while still maintaining a high degree of reliability. This paper discusses the problems experienced with the original fixed geometry bearings, and the progression in bearing upgrades to spherical pivot tilt pad bearings, followed by the more recent application of flexure pivot (FP) bearings. The first set of FP journal bearings was installed in 1994 during a major turnaround. The conventional thrust bearing was also modified to an FP style bearing to help eliminate the brinelling and wear on the pivots and the leveling links. While FP bearings have had success in relatively small high speed integrally geared compressors, this was their first application in a critical utility machine. The analysis and design considerations, along with the vibration data obtained in the field before and after the final conversion to FP bearings, will be presented and discussed.