Control installation for steam turbines working in conjunction with generating boilers steam pressure

摘要

An automatic control system enabling comprehensive operation of a reheat steam turbine with sliding or constant pressure boilers. The control system includes an HP control valve for regulating steam flow to the high-pressure turbine according to load and speed demands, an intercept valve for regulating steam flow to the low-pressure turbine and for reheater pressure control, and a bypass flow system for bypassing excess boiler steam during periods of low loading. The bypass system includes a high-pressure bypass sub-system and a low-pressure bypass sub-system, each having a flow control valve and provision for desuperheating the steam. A signal indicative of actual load demand (ALD) and proportional to the product of boiler pressure and main control valve flow demand is produced. From the ALD signal, reference functions are generated to effect control of the bypass valves. The intercept valve is controlled directly by the ALD signal with a regulation factor inversely proportional to the minimum allowable reheat pressure. Coordinated valve control is effected during all principal phases of turbine operation.