Numerical Simulation Of Temperature Field And Flow Field Distribution In Rotary Kiln During Flux Pellet Production

Taking the rotary kiln of the molten pellets of a certain furnace material company as the model,the data obtained by thermal calibration is taken as the initial parameters.Firstly,the detailed thermal calculation of the rotary kiln system is carried out,then the three-dimensional mathematical model of the rotary kiln is established,and the kiln is calculated.The distribution of flow field,temperature field and concentration field was analyzed.The influence of thermal parameters such as air-fuel ratio and fuel type on the temperature distribution in the kiln was analyzed.The research results are following:1)According to the thermal calculation of flux pellets in rotary kiln under field conditions,the energy consumption index is 1301.83 kJ/kg,the thermal efficiency is 59.96%,the heat utilization rate is 70.4%,and there is still some space for energy saving.2)The three-dimensional mathematical model of rotary kiln is established.The simulation results show that the four-channel pulverized coal burner performed well and can promote the mixing of pulverized coal with primary air and secondary air effectively.However,due to the low volatile matter of anthracite,it is not easy to catch fire.And it forms a kind of flame with a long black head and high local temperature,which is not conducive to the production of flux pellets.The NO_x in the rotary kiln is mainly concentrated in the kiln head area and the high temperature area and the overall content is relatively low,which can control the generation of NO_x better.3)The combustion characteristics and temperature distribution in the rotary kiln were analyzed from the fuel quality and air-fuel ratio.With the increase of coal injection quantity in the kiln,the length of flame and combustion area also increase correspondingly,and the average temperature in the kiln increases.When a lignite,bituminous coal and coke oven gas are used as fuels respectively,the average temperature in the kiln is too low to meet the roasting requirements due to the low carbon content of lignite.However,bituminous coal or coke oven gas can effectively solve the problem of long black head.After further parameter optimization,it can meet the basic requirements of flux pellet roasting and can be considered as a substitute fuel for flux pellet rotary kiln.Reducing the secondary air speed properly are conducive to speeding up the ignition of pulverized coal,shortening the black fire head,and increasing the effective heat transfer area in the rotary kiln and the yield of flux pellets.Fig.35;Table 12;Reference 62.