Abstract: The phenomenon of amplitude fluctuation at 1X frequency appeared after overhaul of the syngas compressor turbine. Through analyzing and troubleshooting the causes, it was finally confirmed that the damage of a carbon brush on the exhaust side of the turbine during overhaul was the root cause of the problem of amplitude fluctuation at 1X frequency. Aiming at the causes of the fluctuation, reasonable measures were taken to successfully solve the problem of amplitude fluctuation at 1X frequency of the steam turbine. This case can provide reference for the overhaul of the steam turbine of syngas compressor units with similar problem.

Key words: steam turbine, 1X frequency, amplitude fluctuation, cause analysis