(中南大学 能源科学与工程学院，长沙 410083)
摘 要: 在铝电解下料过程中，氧化铝颗粒吸热、结块、溶解并受到传热与传质溶解机制的综合作用。基于OpenFOAM计算平台，有效区分主导颗粒溶解的控制机制，考虑气泡作用和下料后的电解质温度响应，开发铝电解槽中氧化铝颗粒传热、传质耦合溶解计算模型；利用Rosin-Rammler分布函数计算下料后电解质中氧化铝颗粒粒径分布，对实际300 kA铝电解槽中氧化铝溶解过程进行数值模拟。结果表明：前18 s氧化铝溶解50%(质量分数)，属于快速溶解阶段；一个下料周期144 s结束后，剩余约1.5%(质量分数)的氧化铝未溶解，未溶解颗粒聚集，并在电解槽底部形成沉淀；仅考虑氧化铝溶解吸热的情况下，下料区位置电解质温度在前1 s快速下降，随后，电解质温度快速回升并在60 s之后呈现震荡趋势。
关键字: 结块；氧化铝溶解；传热；传质；粒径分布；数值模拟
（School of Energy Science and Engineering, Central South University, Changsha 410083, China）
Abstract:During the aluminum electrolytic feeding process, alumina particles will dissolve after absorbing heat, aggregation subject under the control of the mass and heat transfer mechanism. Based on the OpenFOAM computing platform, identifying the dominant mechanism controlling dissolution of alumina, considering the bubble effect and temperature response of electrolyte after feeding, the alumina, dissolution model coupled with heat and mass transfer were proposed. Based on the alumina particle size distribution calculated by Rosin-Rammler function, the actual dissolution process in electrolyte after feeding were simulated in 300 kA aluminum reduction cell. The simulation results show that the first 18 s is the quick stage of dissolution, in which about 50% of the quantity is dissolved. At the end of a feeding cycle 144 s, about 1.5% of the alumina is undissolved, the undissolved particle aggregates and forms sludge at the bottom of the cell. Only considering the alumina endothermic process, the electrolyte temperature in the feeding zone rapidly declines within the first 14 s, then, the temperature quickly is recovered and oscillated after 60 s.
Key words: aggregation; alumina dissolution; heat transfer; mass transfer; particle size distribution; numerical simulation
