| At present,in the process of design and use of Chinese food stoves,most of them rely on experience to design the structure and select burners.There is often the problem of mismatch between flame and furnace structure,which often leads to incomplete fuel combustion.The combustion efficiency and emissions of burners are often jointly determined by multiple influencing factors.However,the existing studies mostly use local analysis,only considering the impact of a single factor on combustion efficiency and pollutant emissions,and few have combined a variety of operating parameters and structural parameters to comprehensively study their impact on combustion performance of burners.In this paper,with the help of numerical simulation,in-depth research on the influence of methane burner efficiency and pollutant emission,so as to provide technical support for the application of methane burner with high energy efficiency and low pollution.Selecting appropriate structure and operating parameters can significantly reduce the NOx and CO emissions of the burner and improve the combustion efficiency.This article is based on the method of numerical calculation established 35 k W blower type kitchen burning gas,the mathematical model and through the actual operation data and the simulation results verify the reliability of the numerical model.A cyclone and a secondary air system are installed on the original blast gas stove.In order to have a better understanding of swirling combustion,this paper carries out cold state simulation and hot state simulation for the burner without and with swirler,so as to provide a clearer comparison.Moreover,based on the installation of hydrocyclone,this paper further improves the simulation,analyzes the combustion chamber height,air coefficient,the ratio of primary and secondary air volume and the incidence angle of secondary air during the combustion of the burner,and finally carries out the range analysis of orthogonal test to analyze and compare the effects of various factors on the combustion efficiency and pollutant emission of the burner.Through numerical simulation,the vortex can be formed in the combustion chamber axis location backflow zone,return can make the products with high temperature not burning blended fuel and air,increase the combustion speed and stability.Through orthogonal test analysis,it can be seen that the main factors affectingNOx emission are air coefficient and primary and secondary air distribution ratio.With the gradual increase of air coefficient,more and more cold air will participate in the mixed combustion,NOx emission shows a trend of first increase and then decrease,NOx emission gradually decreases and tends to be stable with the decrease of the primary and secondary air distribution ratio.The main factors affecting the heat flux at the bottom of the boiler are the primary and secondary air distribution ratio and the height of the combustion chamber.With the decrease of the primary and secondary air distribution ratio,the heat flux at the bottom of the boiler is first stable and then significantly decreased.With the increase of the height of the combustion chamber,the flame is gradually extended,and the heat flux at the bottom of the boiler is first increased and then decreased.Finally,according to the results of simulation and orthogonal numerical experiment,when the height of combustion chamber is 330 mm,the air coefficient is1.15,the primary and secondary air ratio is 2∶1,at this time,the NOx concentration in flue gas is reduced by 58.8%,CO concentration is reduced by 65.7%,and the heat flux of the heated surface is increased by 18.3%. |
