基于VOF模型的锂电解槽流场行为研究及结构优化

Study on flow field of lithium reduction cell and structural optimization based on VOF model

工业锂电解槽是大规模生产金属锂的主体设备。针对锂电解槽内的电解质-氯气-锂液三相流体进行数值模拟建模,研究发现电解质在气泡的带动下形成全槽流动大循环,根据流速分布和流动模式可将氯化锂的加料口设置在相对于出锂口的另一侧。虽然阴阳极间的多孔隔板和集锂罩可有效收集电解产生的金属锂,但金属锂液滴分布发现仍有部分锂液滴存在于集锂罩外,这部分液滴在槽内氯气气氛下发送二次反应从而降低效率。如果将隔板上开孔区域设置于阴阳极投影区域上沿向下20~40 mm处,则可有效减少金属锂液穿过隔板的概率,提高电流效率。

The lithium reduction cell is the main facility for extracting lithium from its compounds in industrial scale.The three phases fluid of electrolyte,chlorine gas and metal liquid in lithium reduction cell is numerically simulated and modeled.It is found that the electrolyte forms a large flow cycle in the whole cell driven by the motion of chlorine bubbles.According to the velocity distribution and flow pattern,the feeding port of lithium chloride should be set on the other side relative to the lithium gathering point.Although the baffle plate with holes between the anode and cathode and the lithium collecting cover could effectively collect the metal lithium produced by electrolysis,there are some lithium droplets distributing out of the collecting cover which will have secondary reaction due to the chlorine gas to reduce efficiency.If the baffle plate is improved by setting the holes below 20~40 mm of the projection area of the anode and cathode,which can effectively reduce the chance of lithium liquid passing through the holes,and improve the current efficiency finally.