The 350MW heating unit with separated high and medium pressure subcylinder which is made by Harbin Steam Turbine Factory Company Limited takes a new steam sealing to improve cylinder efficiency. But it also brings certain problems to the start and operation of the steam turbine. During commissioning period of the unit, there were large bearing vibration, water contained in lowpressure shaft seal, serious steam leakage of highpressure cylinder at shaft end and other faults. Through the onsite troubleshooting, measures such as increasing the rotation rate set point of units warming , optimizing the valve flow control, reinforcing the vibration measuring bracket, eliminating the cylinder expansion resistance, and correcting the highspeed dynamic balance of rotor were taken. After the treatment, the main faults in the generating units are eliminated, which ensures the 168hour successful trial of the retrofit unit with full load.
