烧结镁砂煅烧竖炉内气固传热特性数值分析

Numerical Analysis of Gas-Solid Heat Transfer Characteristics in Shaft Furnace for Calcination of Sintered Magnesia

以年产5×10^(4) t烧结镁砂竖炉为研究对象,基于多孔介质理论,建立竖炉内三维稳态气固流动传热模型,并模拟研究竖炉热工参数对床层内气固传热过程的影响.研究结果表明:冷却风流量每增加10%,出口烟气温度降低50℃,出口球团温度降低80℃;冷却段长度每增加5%,出口球团温度降低25℃.以竖炉出口烟气温度和球团温度为优化目标函数,得到竖炉最适宜结构和操作参数,即煅烧风流量为2606.67 m^(3)/h,冷却风流量为2203.34 m^(3)/h,预热煅烧段长度为6.64 m,冷却段长度为11.70 m.在此竖炉运行工况下,出口球团温度为288.75℃,出口烟气温度为414.32℃.

Based on the theory of porous media,a three-dimensional heat transfer model for steady gas-solid flow was established for a shaft furnace of sintered magnesia with annual output of 5×10^(4) t.The influences of thermal parameters of the shaft furnace on the gas-solid heat transfer process in the bed were simulated.The results show that,with increasing the cooling air flow by 10%,the outlet flue gas temperature decreases by 50℃,and the outlet pellet temperature decreases by 80℃.When the cooling section length increases by 5%,the outlet pellet temperature decreases by 25℃.Taking the flue gas temperature and pellet temperature at the shaft furnace outlet as the optimization objective functions,the optimum structure and operation parameters of shaft furnace are obtained,including the calcination air flow of 2606.67 m^(3)/h,the cooling air flow of 2203.34 m^(3)/h,the preheating calcination section of 6.64 m,and the cooling section of 11.70 m.Under this working condition of the shaft furnace,the outlet pellet temperature is 288.75℃,and the outlet flue gas temperature is 414.32℃.