| 摘要 |
PURPOSE:To aim at simplification of the structure and control system of a turbine by controlling the back-pressure, medium-pressure extraction steam pressure and pressures of the mixed-pressure system in a mixed-pressure back-pressure extraction steam turbine by means of control valves in response to pressures at the fixed places respectively. CONSTITUTION:The captioned plant is provided with a coal-fired boiler 3 as a high- pressure boiler, a recovery boiler 1 as a medium-pressure boiler, an extraction steam turbine 2 and a mixed-pressure back-pressure extraction steam turbine 14. In addition, the steam line 20 from a coal-fired boiler 3 is connected to the entrance of the turbine 14, and the steam line from the recovery boiler 1 is connected to the turbines 2, 14 respectively. Hereupon, to the back steam line 7 of the turbine 14 is connected an exhaust cooler 15, and the back-pressure is controlled by means of a control valve 16 provided at the entrance of the exhaust cooler 15 in response to pressures in the line 7. In addition, the medium-pressure extraction steam pressure and pressures of the mixed-pressure system are controlled by means of control valves 13, 8, provided on a medium-pressure extraction steam line 12 and the steam line 20 respectively, in response to the pressure in the steam lines 12, 10 respectively.
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