Thermodynamic Performance Simulation On 6B Gas Turbine Combined Cycle System With Various Fuels

Electricity generation by gas-steam combined cycle is a trend for nowadays electricity produce of China,whose adoption is becoming more and more popular.In the running of the unit,the practical operating circumstance and parameters may differ from those originally designed,e.g.,the change on fuel,the change on long-term load and design load.All these changes will affect the combustion and the thermal performance of a running unit.So it is of significant guidance for engineers to study the operating performance of gas turbine under off design condition and off design fuels.In this thesis,a 6B type gas turbine combined cycle system in Daqing Gas Turbine Power Plant was used as the research model.Firstly,the CFD platform was used and a simulation model was developed for the 6B type gas turbine chamber.The combustion process of the 6B type gas turbine chamber under different fuel conditions was simulated.The operation condition of the chamber under different fuel conditions was analyzed and the possibility of changing the fuel for gas turbine was evaluated.Then,GT-Pro software was used to establish the flow model of the gas turbine combined cycle,including gas turbine,heat recovery steam generator(HRSG),and steam turbine and so on.The model was validated according to the unit operation data.At the end of the thesis,two aspects are researched.One was the operating characteristics of the unit when the load of the gas turbine power plant was changed from 50 to 100% and fuel was original associated gas.The generation power and efficiency of the unit under different load were compared.The simulation results show that the economy of the gas-steam combined cycle unit decreases with the load of the gas turbine,but it is not linear due to the combustion of the unit and the performance of the compressor.There is an inflection point at 90% load.When the fuel changes,the economy of the gas-steam combined cycle unit will also change.Without consideration of other factors,the unit economy using low heat value fuel becomes better.For the combustion performance of the chamber using low heat value fuel,the temperature distribution becomes more uniform and the stability is enhanced.