Analysis and treatment of abnormal vibration for low-pressure cylinder of 660 MW steam turbine units

Abstract

Aiming at the abnormal vibration phenomenon of low-pressure cylinder during the debugging period of a new 660 MW ultra-supercritical steam turbine unit， through vibration test and analysis， it is concluded that the bearing bush of low-pressure cylinder has low dynamic stiffness and its resonance frequency is close to the working speed， if the shaft vibration climbs due to factors such as dynamic and static rubbing， the tile vibration will be caused to climb significantly. At the same time， it is found that the gap between the low-pressure outer cylinder and the cosmetic plate is too small， which will induce the generation of low-frequency structural resonance. During the operation of the unit， measures are taken to adjust the steam supply temperature of the low-pressure shaft seal and control the load of the unit. During the maintenance， measures such as adjusting the clearance of the cosmetic plate of low-pressure cylinder， the installation size of the bearing， and the fine dynamic balance are adopted to reduce the abnormal vibration of the low-pressure cylinder， which improves the stability of the low-pressure cylinder and ensures the safe and reliable operation of the units.

Keywords

• low-pressure cylinder
• structural resonance
• dynamic and static rubbing
• shaft seal