Study On Combustion Characteristics And Emissions Of NH3/CH4 Chamber

With its high hydrogen density and already existing infrastructure,ammonia(NH3)is believed to be an excellent green fuel that can be used in energy generation and transportation systems.Ammonia and blends of ammonia with methane are gaining increased interest as fuels for gas turbine applications.However,combustion of ammonia has certain challenges that need to be addressed before its widespread use in practical systems.In order to study the combustion characteristics of ammonia-methane-air combustion in gas turbine combustion chambers and the emission of nitrogen oxides and carbon oxides(NOx,CO2 and CO),the gas turbine annular combustion chamber is designed by thermodynamics and aerodynamic calculation.Modeling is performed using SOLIDWORKS software,meshing it with the meshing software ICEM,and then simulating the three-dimensional operating conditions by using the commercial software FLUENT.The modified CH4/NH3 chemical reaction kinetics mechanism is used in the simulation to study the combustion law under different conditions by changing the mass fraction of NH3 in the ammonia-methane fuel and the temperature of the inlet air of the combustion chamber,combined with the previous references,the following conclusions are obtained through analysis:(1)In the self-designed gas turbine annular combustion chamber,the simulation results show that with the increase of NH3 content in the fuel,the combustion process in the combustion chamber is still stable,and the trend of the temperature curve is about the same.However,the high temperature region in the combustion chamber is gradually reduced.The combustion temperature of the mixing zone and the cooling zone in the combustion chamber decreases overall,and the combustion chamber outlet unevenness decreases.(2)With the increase of ammonia content in the fuel,the axial velocity of the combustion chamber changes in the same trend,but the area where the axial velocity on the centerline is negative increases,which corresponds to the increase of the central recirculation zone.(3)As the mass fraction of ammonia in the fuel decreases and the mass fraction of methane increases,the CO mass fraction in the combustion chamber does not decrease but increases,and the high concentration region gradually moves toward the exit position of the combustion chamber.With the increase of ammonia content in the fuel,the emissions of NOx,COZ and CO at the outlet of the combustion chamber are all significantly reduced.(4)Keep the other conditions unchanged,and then change the inlet temperature of the combustion chamber to 500K,600K,700K,and 800K,respectively.The outlet content of Noxn CO and CO2 decreases with the decrease of the inlet temperature of the combustion chamber.(5)Keep the other conditions unchanged and change the gas plan.The simulation results show that as the gas distribution of the jet orifice of the combustion chamber increases,the combustion chamber outlet is more uniform,and the pollutant discharge of the combustion chamber is significantly reduced.