Research On Performance Of Low Nitrogen Full Premixed Burner With Flame Stabilization

With the frequent occurrence of haze weather,the policy of"changing coal into coal gas"is vigorously promoted in China,while the NO_X emission requirements generated in the process of gas combustion are increasing day by day.In this situation,low nitrogen combustion becomes the key development direction of gas burners in the future.In order to solve the problems of poor stability of flame and complex structure in full-premixed burner,a full-premixed low-nitrogen burner with pilot flame was designed according to the flame stability principle and NO_X formation mechanism in this work,which has stable flame and simple structure.Selecting this full premixed burner with pilot flame as the research object,the performance parameters of the burner including flame stability,NO_X and CO emission,and flame height were studied by means of numerical simulation and experiment,and the optimal operating condition and structure of the full-premixed low-nitrogen burner were obtained.The physical model of the laminar premixed finite rate was established,and the chemical reaction mechanism adopted CH₄-skel with multi-component and multi-reaction mechanism.Numerical simulations show that the flame with flame stabilization has the highest temperature in the interaction area between flame stabilization and main flame,the temperature near the root of main flame is higher,and the stability of flame is higher.The NO concentration of the flame without combustion flame reaches the highest value above the flame surface,while the NO concentration of the flame with combustion flame reaches the highest value only above the tip of the flame cone.Due to the presence of flame stabilization,the flame high temperature and high oxygen areas are pulled down,and the average concentration of NO is significantly lower than that of flames without flame stabilization.The experimental system was built,in which the gas flow can be flexibly adjusted,and then the burners with different structural parameters of the flame stabilizer were fabricated to perform experiments.The effect of operating condition of the burner(including primary air coefficient,?,and pilot flame quantity,Q_stable)and structure of the flame stabilizer?horizontal distance from the flame hole to the edge of the main fire hole,s,different diameter,d,and different number of flame hole,n?on flame stability,NO_X and CO emissions,and flame height were analyzed.The results show:when?_mainain is between 0.95-1.35,with the increase of?_main,the flame stability keeps decreasing.When the flame stabilization amount accounts for 5%-15%,the flame can burn stably.As s increases,d decreases,and n decreases,flame stability decreases.As s increases,the NO_X and CO emissions decrease,and H_r-flame-flame increase gradually.When s=2.0 mm,the NO_X emission reaches the lowest value,17 mg/m³.As d decreases,the NO_X emission decrease,the CO emission decreases first and then increases,and H_r-flame-flame increases gradually.When d=1.0 mm,the NO_X emission reaches the lowest value,17 mg/m³.As n decreases,the NO_X emission decrease,the CO emission decreases first and then increases,and H_r-flame-flame increases gradually.When n=8,the NO_X emission reaches the lowest value,16 mg/m³.Considering the effects of flame stability and CO emission,the flame stabilizer S1?s=2.0 mm,d=2.0 mm,n=16?is the optimal stabilizer.