金属锂还原罐内化学反应与传热耦合特性

Coupled properties of heat transfer and chemical reactions in lithium production retorts

为了分析真空热还原制取金属锂的还原效率和还原率,综合考虑罐内球团传热和化学反应,建立了传热与反应动力学耦合模型.利用该模型对单球团和还原罐内球团还原过程进行数值模拟,得到了球团温度及还原率的时间分布,并分析了罐外换热系数对球团还原过程的影响.结果表明:球团低导热率和反应等效热汇是影响还原过程的主要因素,罐中心区域和罐壁处的温度和反应速率存在较大差值;还原初期传热为还原过程的主要控制因素,而反应后期化学反应为主要控制因素;罐外换热系数对还原过程影响不大,增强罐内传热是提高还原效率的有效途径.

A coupled heat transfer and reaction kinetics model was established to study the lithium production efficiency and reduction rate of lithium production retorts. Numerical simulation of the pellet reduction process by this model was performed to obtain the time distributions of pellet temperature and reduction rate, and the effect of effective heat transfer coefficient outside the retorts on the pellet reduction process was analyzed. It is found that the low thermal conductivity of pellets and the chemical reaction equivalent heat sink are the main factors affecting the pellet reduction process. In the beginning of the reaction, heat transfer is the main controlling factor, but in the later, reaction kinetics is the controlling factor. The effective heat transfer coefficient outside the retorts has less influence on the pellet reduction process. Enhancing the heat transfer coefficient inside the retorts is an effective way to improve the production efficiency.