Patent ID: 7509794
Filing Date: 2009-03-31
Classification: F22B,Y02E

Abstract:
1. A waste heat steam generator for a gas and steam power station, comprising: a waste heat boiler that is supplied exhaust gas from a gas turbine at a waste heat boiler inlet opening; multiple evaporators, including a high pressure evaporator, a medium-pressure evaporator, and a low-pressure evaporator arranged in the waste heat boiler to generate operating steam for a steam turbine, the high pressure evaporator connected to a high pressure steam drum, the medium-pressure evaporator connected to a medium pressure steam drum, and the low-pressure evaporator connected to a low pressure steam drum so that steam can be generated; a heating device that supplies flue gas to the waste heat boiler; an air control valve for controlling air entering the heating device; a feedback line to feed back the flue gas to a circulation circuit; a flue flow rate control valve for controlling the rate flue gas is applied to the circulation circuit; wherein the circulation circuit has the heating device connected to it and is formed by a heating path through the waste heat boiler and the feedback line and a portion of the flue gas can be extracted at a point from the waste heat boiler and can be fed back to the inlet opening into the waste heat boiler; and a slide connected to a respective feed water supply line and the respective steam drum in at least two of the evaporators so that when the selected supply line is opened or closed steam generation in the corresponding pressure stage is controlled; wherein the heating device, heating device air control valve, flue rate flow control valve, and the slides allow auxiliary steam to be extracted from a low pressure evaporator by selectively controlling the high pressure evaporator and medium pressure evaporator in operating situations in which no exhaust gas is available from the gas turbine, including when the gas turbine is not in use or while the gas turbine is being started up or shut down.