Instability Vibration Solution on Turbine Shaft Caused by Unreasonable Distribution Mode of Steam Turbine

The high pressure regulating valves original opening sequence of unit 2 inShenhua Yili Energy Co.,Ltd.Power Plant was No.1 and 2,then No.3,No.4.Theunreasonable distribution of turbine,unbalanced steam flow exciting force occurred on theshaft,resulted in the shaft vibration instability when unit load changing.Turbine highpressure regulating valve opening sequence was changed as symmetrical inlet way of No.2and 4,then No.1,No.3,which eliminated the unbalanced steam flow excitation force.Atthe same time,optimized the valve overlap,reduced throttling loss,not only solved theturbine shafting vibration problems,but also improved the thermal efficiency of the unit.