Study Of Combustor Simulation And Operating Characteristic For Gas Turbine Using Low-calorific-value Fuel Gas

GT(Gas Turbine) is the most advanced thermal power plant. In addition to the aviation sector, the scope of its application includes electric power industry,petrochemical industry, transportation industry and so on. In these industries, GT is as a power of generators, oil and gas pipeline, ships and tanks and other equipment.GT has the performance advantages of high thermal efficiency, low pollution emissions, starting fast, using less water and burning a variety of fuels, etc., to save energy and protect the environment is of great significance.Low-calorific-value fuel gas GT can burn biomass gas, factory emissions, etc.,and be used in power generation or factory. So that it will help to improve energy structure and promote energy conservation in china. Therefore, the study of low-calorific-value fuel gas GT is of great significance for Chinese economy and environment. Compared with high calorific value fuel gas, the fuel composition of low-calorific-value fuel gas changes and its calorific value is low, so that its combustion characteristics change and it results in change in the gas turbine operation. In this paper, to solve the above problems, the impact of the low-calorific-value fuel gas on gas turbines is analyzed in combustor characteristics and operating characteristics of GT.In this thesis, the chemical reactor network model of GT’s combustor is established, then the GT combustion chamber simulation is done. From the two aspects of calorific value and components of the fuel, the impact of the low-calorific-value fuel gas on combustion characteristics is analyzed, combustion characteristics which mainly analyzes the equivalence ratio, inlet temperature and pressure of the combustion chamber and other factors, to effect on adiabatic flame temperature, outlet temperature of combustor, emissions of CO and NO. Also the effects of the low-calorific-value fuel gas on operation characteristics of GT is studied. Based on the thermodynamic cycle of GT and thermodynamic properties of gas, and combining the compressor characteristic curve, combustor thermal equilibrium and turbine characteristic curve of GT, the operating characteristic calculation model of the GT is established. The operating characteristics of the 14 kinds of low-calorific-value fuel gas are calculated, then the effect of the calorific value on coefficient of fuel, fuel flow, the turbine outlet temperature and expansion work is analyzed.To simulate combustion chamber of GT, the results show that the equivalence ratio is an important factor to affect on the combustion characteristics of thelow-calorific-value fuel gas. So that it is to determine the corresponding optimal equivalence ratio for the fuel after switching to the low-calorific-value fuel gas. For the middle calorific value fuel, its adiabatic flame temperature and outlet temperature of combustor are higher than natural gas, and the exhaust emissions is also higher than natural gas. For low calorific value fuel, because the calorific value of the fuel is low, it is difficult for the fuel to organize combustion, and its adiabatic flame temperature and outlet temperature of combustor are lower than natural gas.The combustion characteristics of the low-calorific-value fuel gas is not only relevant to the calorific value of the fuel, but also related to the fuel component. The more the proportion of combustible gases in the fuel gas is, the higher the adiabatic flame temperature and outlet temperature of combustor is.To simulate operating characteristics of GT, the results show that the lower the calorific value of the fuel is, the more the fuel flow and the fuel coefficient is. In the calorific value range of 10MJ/kg~16.7MJ/kg, the increased extent of the fuel flow with the reduction of calorific valueof the fuel is less. In the calorific value range of4.3MJ/kg~10MJ/kg, the increased extent of the fuel flow with the reduction of calorific valueof the fuel rises fast. The calorific value of the fuel less affect turbine outlet temperature, mainly between 563℃~578℃. The lower the calorific value of fuel gas is, the more expansion work of the gas formed by combustion in the combustor is done.In addition, for the low-calorific-value fuel gas, the program of calculation interface about GT operating characteristics is designed. It is convenient for users to operate calculations.