稀土电解槽流场-电场耦合数值模拟

Numerical Simulation of Flow Field-electric Field Coupling in Rare Earth Electrolytic Cell

为了研究稀土电解槽阳极生成气体对电场影响,利用CFD软件二次开发功能建立气-液两相流场-电场耦合模型,首次提出将电场电导率与阳极气体气含率关系相结合的稀土电解槽流场-电场耦合数值模拟,并对比有无阳极气体气含率影响的电场电势云图及流场分布情况,研究发现,稀土电解槽阳极生成大量气体并在阳极表面形成动态气层,使得阳极附近熔盐扰动较为剧烈,其气液两相流区域的熔盐与阳极生成气体的混合相电导率受气体波动影响发生变化,熔体内部电场分布受到阳极生成气体影响,通过获取阳极深度175 mm、250 mm、300mm、350 mm、395 mm处的阳极生成气体气含率分布情况,发现气液混合相区域电导率随阳极生成气体气含率增高而增高,阳极上部生成气体气含率及动态气层厚度大于阳极下部,阳极气体气含率的熔体内部电场阳极上部电压降快于下部,电场等势线整体呈斜型分布,阳极上部部分区域电场等势线受到生成气体扰动影响呈现波动,同X坐标下槽内熔体电压上部小于下部,而电解槽底部由于为单相区,该处电场分布并未受到阳极气体直接影响。

For the purpose of studying the effect of anode gas on electric field in rare earth electrolysis cell,the secondary development function of CFD software was used to build the gas- liquid two- phase coupling model. The concept of combining conductivity with anode gas volume fraction in rare earth electrolysis cell numerical simulation was first presented. The electric field potential and anode gas distribution with and without considering the anode gas volume fraction were compared. The results show that a large amount of gas was generated from the anode surface and formed a dynamic gas layer which make the fused salt flow quickly. The electric field distribution is affected by the anode gas in rare earth electrolytic cell. By analyzing the gas concentration fraction of anode in the depth of 175 mm,250 mm,300 mm,350 mm and 395 mm,It is found that mixed phase conductivity rises with the anode gas volume fraction. The upper anode gas volume fraction and gas layer are larger thickness than the lower ones,the voltage drop of upper anode is larger than that of lower part. Partial electric field distribution in upper anode field is affected by anode gas obviously,and the upper voltage is larger than lower one at same X coordinate. The electric field equipotential line presents inclined type. As the bottom of rare earth electrolytic cell is single phase field,its electric field distribution is not affected by the anode gas directly.