Numerical Simulation Of New Combustion Technology

The optimization of energy structure drives the proportion of natural gas in primary energy consumption to increase continuously.Efficient and clean utilization of natural gas through various combustion modes has become an increasingly important aspect of energy conservation and environmental protection.It is a key problem in the numerical simulation of combustion process to predict the harmful gases produced by combustion.In view of methane combustion system,the integration of chemical dynamics simulation and CFD numerical simulation and the development of harmful gas prediction method in combustion process can provide an important means and way for the efficient and clean utilization of natural gas.The main conclusions are as follows:1.The chemical kinetic model of methane combustion system was established,and the combustion characteristics of methane under different components were studied?1?In the range of equivalence ratio,the adiabatic flame temperature is parabola distribution,and the highest value is located at a little fuel rich equivalence ratio???1.05?;in the region of low equivalence ratio and high equivalence ratio,the mole fraction of nitrogen oxide is very low.?2?Carbon dioxide,nitrogen and argon are respectively added to the fuel side as dilution gas,and the combustion temperature decreases in turn.Under the same dilution ratio,the addition of carbon dioxide is more effective to reduce the formation of nitrogen oxides.?3?The combustion temperature of the mixture combustion of hydrogen and methane is low,and the larger the mixing ratio is,the larger the temperature reduction range will be;the addition of hydrogen makes the temperature rise rapidly,the more the hydrogen content is,the faster the temperature rises,indicating the combustion supporting effect of hydrogen;the combustion of hydrogen mixed with methane,the lower the ignition temperature,the larger the mixing ratio,the lower the ignition temperature.2.The two swirl combustion model of methane combustion system is established,and the results show that:?1?There are two basically symmetrical small vortices in the dead corner area at both sides of the bottom of the combustion chamber,and two strong vortices in the middle of the combustion chamber.The middle of the vortices is the central return area.The length of the return area in the hot flow field is slightly shorter than that in the cold state,and the negative return velocity in the hot state is larger than that in the cold state.?2?The overall temperature field is basically axisymmetric,with the maximum temperature gradient near the burner outlet;CO₂ is mainly distributed near the combustor outlet;H₂O is mainly distributed in the combustor wall area.3.Based on the above research,a reactor network model for numerical simulation of combustion process is proposed to solve the prediction problem of trace harmful gases.The specific methods are as follows:according to the characteristics of velocity field,temperature field and concentration field,the combustion space is divided into typical ideal reactors;considering the number and shape of the zones comprehensively,the reactor type is determined with residence time as the main discrimination parameter;the ideal reactor is connected to the reactor network,and the calculation of the reactor network is to obtain the value of trace harmful gases.The simulation results of reactor network show that the emissions of CO,no and NO₂ decrease in turn,and the production of NO₂ increases with the decrease of load.