High Vibration of a 125MW Steam Turbine During Run-up and Coast Down

摘要

High vibration of a 125MW Steam Turbine No. 1 and No.2 bearings during run-up was reported in November, 1996. After the mechanical maintenance section inspected both bearings and found that they were normal, subsequent run-up of the turbine after the inspection indicated that the high vibration still persisted. Predictive Maintenance Team (PMT) was asked to investigate into the problem. Since the high vibration occurs only during turbine run-up and coast down, PMT suspects that the possible causes of the high vibration are vibration sensor defect, unbalance (thermo-unbalance, rotor bow), rubbing and rotor problem (rotor or blades crack). Run-up and coast down spectra with phases were recorded by an off-line vibration data collector on 23rd December 1996 and 29th January 1997. After analyzing the vibration results, possibility of such high vibration due to sensor defect, unbalance (thermo unbalance, rotor bow) and rubbing was low. The cause of high vibration of LA Turbine during run-up and coast down may be due to rotor problem. Details of investigation (and findings) are discussed in this paper.