Shaft seal steam turbine shutdown method

The invention provides a shaft seal steam turbine shutdown method, which belongs to the field of gas turbine-steam turbine combined cycle power generation, and comprises the following steps of: sequentially closing a furnace side reheating main steam electric valve, closing a medium-pressure steam pocket to reheating main steam electric valve, closing a furnace side low-pressure main steam electric valve, closing a steam turbine side main steam pipeline drain valve and manually adjusting a high-pressure bypass adjusting valve; the pressure after the valve is controlled does not exceed 3 MPa, meanwhile, the shaft seal steam overflow valve is manually controlled, the opening degree of the shaft seal overflow valve is reduced as much as possible, shaft seal steam is prevented from being discharged to a condenser through the shaft seal overflow valve, and the flow of the shaft seal steam is reduced. After the vacuum of the steam turbine reaches zero, shaft seal steam supply is stopped; and an electric door from t