Analysis of Nitrogen Oxides Formation in CH4/Air Laminar Premixed Flame

Many combustion processes seriously pollute the environment because of producing nitrogen oxides emission, which abstracts wide attention from researchers. How to reduce nitrogen oxides emission is important to protect the environment. At the present work, a reduction mechanism based on a detailed chemical reaction kinetics mechanism, Gri_Mech3.0 was adopted to analyze nitrogen oxides formation in a CH4/air laminar premixed and turbulent diffusion flames, a two dimensional turbulent diffusion flame was simulated with the EDC model. Parameters were obtained, including flame temperature, burning velocity and mass fraction of nitrogen oxides. The results of laminar premixed flame show that nitrogen oxides emission mainly comes from the thermal and prompt NO mechanisms. A large amount of free radicals O, H and OH produced by combustion processes provide reactants for the reactions of nitrogen oxides formation. Mole fraction of nitrogen oxides increases with the increasing of both flame temperature and chemical equivalence ratios. By contrast, there is a lower mass fraction of nitrogen oxides formation for the fuel-lean flame.