Simulation Of The Combustion Process Of Metallurgical Lime Shaft Kiln

Lime is indispensable auxiliary materials in the process of steel-making. Withthe continuous development of metallurgical technology, the requirement of lime inmetallurgical process is higher and higher. In order to meet the requirement of lime’squality in metallurgical process, further more studies of lime production process byshaft lime kiln is necessary, so that the structure of the lime kiln can be optimized, thequality and production process of the lime can be improved.Lime is produced by a new gas burning shaft lime kiln which daily output is300t/d in a metallurgical lime factory, but its productivity and quality of lime is nothigh. In order to further improve the productivity of gas burning shaft lime kiln andthe quality of lime, reduce the unburnt rate of lime, in this paper, according to theactual equipment process parameters of the metallurgical lime factory, the threedimensional mathematical model of gas burning shaft lime kiln is established tosimulate the process of the burning and heat transferring in it.The flow and combustion of the gas fuel in the gas burning shaft lime kiln is atypical problem of combustion in the porous medium. In this paper, the flow field andtemperature field of the gas burning shaft lime kiln are simulated by laminar orturbulent non-premixed combustion in porous medium model. The result of thesimulation shows that, the reason of the low productivity of the gas burning shaft limekiln and the high unburnt rate of the lime produced in it is the unreasonabledistribution of the temperature in it, which is showed that, the ratio of blast furnacegas and combustion-supporting air is unreasonable, and the height of the kiln is notcorrespond with the amount of gas. According to the simulation of different ratio ofblast furnace gas and air, primary air is the major combustion-supporting air, andsecondary air is cooling air, only a few part of secondary air participate intocombustion, the ratio of blast furnace gas and primary air should be controlled about1:0.76. The height of kiln has a great influence on temperature field of it, in thecondition of the same gas amount, the lower the kiln is, the shorter the distance fromthe high temperature area to the exit is, the more heat loss is. The analysis resultssuggest this metallurgical lime factory that the appropriate height of the gas burningshaft lime kiln should be rebuilt to16m, and the volume flow rate of the blast furnacegas should be appropriately reduced to14875Nm3/h.