镁电解槽多场多相耦合作用下液态镁珠运动特性研究

With the 100,000 tons/year of magnesium metal electrolysis production line in Qinghai province will soon be put into operation, the fundamental research of multi-physics coupling in magnesium electrolysis cell is crucial for the technical support of the industrial production. Current efficiency of magnesium electrolysis cell is an important production target, which directly affects the energy consumption. The optimization of the motion of magnesium droplet in the electrolyte is the key to improve the current efficiency. The viscous force of the rising bubble formed at the anode and the electromagnetic force under high current are the primary cause of the electrolyte flow. To improve the magnesium electrolysis technology, the motion characteristic of magnesium droplets must be researched based on the multi-physics fields and multi-phases coupling model. Mathematical model of coupling between the multi-phase flow field and thermo-electro-magneto field will be built and solved by numerical simulation. The electrolyte flow field in the electrolysis experimental cell under the effects of the electromagnetic field will be obtained by Particle Image Velocimetry (PIV) and Volumetric Three-Component Velocimetry (V3V). Moreover, the experimental data will be used to modify the mathematical model. Motion characteristic and the primary separation rate of magnesium droplet was analysis by particle tracing method. The effects of the structure and technological parameters of magnesium electrolysis cell on the energy consumption and primary separation rate of magnesium droplet will be investigated for designing a magnesium electrolysis cell with low energy consumption and high current efficiency.

随着青海10万吨/年金属镁生产线即将建成投产，开展镁电解槽多物理场耦合基础性研究为生产提供技术支持至关重要。电解槽电流效率是镁电解一个重要的基本生产指标，它直接影响电解槽的产量与能耗，提高电流效率的关键在于优化液态镁珠在电解质中的流动状态。电解质流动是由氯气上浮产生的相间作用力和槽内电磁力的共同作用造成的。为提升镁电解技术，必须在多物理场复杂体系下研究液态镁珠的运动特性。本项目以含电场、热场、磁场、多相流场的多物理场多相耦合模型和群体平衡模型为基础，综合利用PIV和V3V激光测速技术，通过实验与模拟数据相对比，形成镁电解槽多场多相耦合模型，并提出相应的计算手段和分析方法，开展多场多相耦合作用下液态镁珠运动特性研究，优化镁珠运动路径，提高镁珠分离率。多场多相耦合模型为设计高效率电解槽奠定理论基础和参考依据，同时对于丰富和拓宽多场多相耦合基础理论的发展具有重要的理论意义和应用价值。

含电场、热场、磁场、多相流场的多物理场多相耦合模型是镁电解槽仿真计算的基础。项目针对多场多相耦合计算的难题，结合PIV和V3V激光粒子测速技术所得数据，形成经过验证的镁电解槽多场多相耦合模型，建立了多场之间的耦合关系，揭示了多场多相耦合机制。项目系统研究了电解槽热量的产生和耗散方式，分析了影响电解槽能量平衡的结构及工艺参数；研究了冷模实验中液相的三维和二维流动规律；分析了镁电解槽内的磁场分布及电流强度和极间距的影响；通过追踪镁珠的运动特性，提出了镁珠一次分离率的概念，并在改变电解槽结构和工艺参数后发现现有槽型不利于镁珠一次分离，进而影响电解槽的电流效率；课题进一步提出了三种新型阴极结构和不同进电方式的槽结构，不同程度地提高了镁珠一次分离率。项目基于电-热-磁-流多场多相耦合模型获得的电解质流动规律，丰富和拓展了镁电解槽放大设计和工艺结构优化的基础理论，为低成本高效设计高温电解槽提供理论基础、新方法和参考依据。