in a combined cycle power plant with a gas turbine circuit and a steam turbine circuit , the exhaust gases from a gas turbine transfer their residual heat to a steam turbine via the working medium flowing in a once through steam generator . the deaeration of the working medium is carried out in the hot well of the steam turbine condenser , the deaerated working medium is introduced directly from the hot well of the condenser via a feed pump into the preheating surfaces of the once through steam generator , and a separating bottle for the blowdown of impurities is arranged between the evaporation surfaces and the superheating surfaces .