炼镁还原罐内传热及其强化换热分析

Analysis of heat transfer and enhancement in magnesium reduction tank

在碳达峰碳中和背景下,皮江法炼镁工艺的高能耗问题不容忽视,而造成该工艺高能耗的原因之一是还原罐内物料传热效率低下。为提高还原罐的传热效率,对还原罐内的传热过程进行数值模拟,分析球团直径、球团初始温度、还原罐内径和肋片参数对还原罐径向传热性能的影响规律。结果表明:球团直径越大、初始温度越高、还原罐内径越小,越有利于热量向还原罐内部传递,其中球团直径的变化对还原罐中心温度变化影响最大,直径为18,25,32 mm和39 mm的球团依次加热7,5,4 h和3 h后,达到还原反应所需温度(大于1300 K);肋片长度越长、宽度越宽、数量越多,对还原罐中心温度的提升效果越明显,其中肋片长度的变化对其影响最大,肋片长度由65 mm以25 mm增量增至115 mm,加热1 h时,还原罐中心温度依次增大16.8%、9.6%。研究结果为皮江法炼镁还原罐的换热及其强化提供理论参考,也为缩短炼镁周期提供很好的解决思路。

Under the background of peaking carbon neutrality,the high energy consumption of the Pidgeon’s process of magnesium smelting cannot be ignored,and one of the reasons for the high energy consumption of the process is the low heat transfer efficiency of the materials in the reduction tank.In order to improve the heat transfer efficiency of the reduction tank,the heat transfer process in the reduction tank was numerically simulated,and the influences of pellet diameter,initial temperature,inside diameter and fin parameters on the radial heat transfer performance of the reduction tank were analyzed.The results show:the larger the pellet diameter,the higher the initial temperature and the smaller the inner diameter of the reduction tank,the more favorable the heat transfer to the inside of the reduction tank,in which the change of pellet diameter has the greatest influence on the change of temperature in the center of the reduction tank.The pellets with diameters of 18,25,32 mm and 39 mm were heated successively for 7,5,4 h and 3 h to reach the required temperature of reduction reaction(greater than 1300 K).The longer the length,wider the width and more fin,the more obvious the improvement effect on the center temperature of the reduction tank is,among which the change of fin length has the greatest influence,the fin length increases from 65 mm to 115 mm in an increment of 25 mm.After 1 h heating,the center temperature of the reduction tank increases by 16.8%and 9.6%in turn.The results provide a theoretical reference for the heat exchange and strengthening of the reduction tank in Pidgeon’s process of magnesium smelting,and also provide a better solution for shortening the cycle of magnesium smelting.