Thermal Analysis Of The M701F Gas-steam Combined Cycle Unit Under Variable Conditions

Gas-steam combined cycle power plant has the following advantages：high efficiency,low pollution and excellent peaking performance.The gas-steam combined cycle in actualoperation cannot always be operated under the design condition because affected by manyfactors, such as atmospheric temperature, atmospheric pressure and humidity, fuel ofcombustion and blade fouling.So in order to understand the unit performance comprehensively, we not only to masterthe performance of design conditions, and also need to know the features of unit undervariable conditions,which requires the calculate and analysis of the combined cycle unit.In this study, M701F combined cycle units with a domestic power plant is taken forstudy. The factors of the off design condition property of gas-steam combined cycle unit wereanalyzed in detail,including fuel heating value, atmospheric temperature, the unit load,atmospheric pressure, atmospheric humidity and blade fouling and so on.The gas-steam combined cycle was decomposed to three mathematical modules: gasturbine, heat recovery steam generator and steam turbine making use of the modular modelingmethod. Gave the model reasonable hypothesis and simplification， the performanceparameters of a M701F gas steam combined cycle unit were calculated, before and afterwashing. The mathematical module of gas turbine was proved correct by comparison with thegas turbine actual operating data. At the same time， the compressor washing wastheoretically proved necessary from the data analysis, which provides a theoretical basis ofthe must wash cycle and the best wash cycle of gas turbine.