Simulation And Structural Optimum Design Of Large-diaphragmless Magnesium Electrolyzer

The key Equipment to produce magnesium metal is the fused salt cell, its development and progress represents the process reform of electrolysis. There are many physical fields involved in the production of magnesium, such as electric field, thermal field, velocity field, concentration field, stress field, magnetic field, and which are the main technical problems for progress of molten salt cell due to the complex interactions among physical fields.Perfect distribution of physical fields could effectively improve electrolysis efficiency, however, the development of magnesium electrolysis cell is very slow, researches on physical fields are few. In order to develop the large advanced magnesium electrolyzer of our own country, to deeply study the physical fields of magnesium electrolyzer are of great significance. Therefore, this paper mainly focused on study on electrical field, thermal field and thermo-electric field, and based on which to design and optimize large magnesium electrolysis cell.In this paper, based on the simulation technologies of finite element software ANSYS, 3D steady models of electric field and thermal field are built, and simulation computation programmes of electric field and thermal-electric field were written with APLD language, which is good to quickly investigate the effect of parameters changes on physical fields of cell, and improved the optimization design efficiency of magnesium electrolyzer.In order to provide design criteria for large advanced electrolyzer, this paper is based on 120kA magnesium electrolyzer, detailed work were conducted to study the effect of amperage, current density, structure of anodes and cathodes, ACD, the relative position between anodes and cathodes, the height of electrolyte on the electric field. The thermal simulation of magnesium electrolyzer mainly focused on the effect of structure and process parameters(amperage, electrolysis temperature, environment temperature, convection coefficient of anodes, convection coefficients of other parts, ACD) on the heat dissipating capacity, heat balance difference and temperature field.Finally, based on the optimization design of electric field and thermal field, a new design method of magnesium electrolyzer was proposed to design 430kA cells, and 6 solutions for magnesium electrolysis cell were achieved. According to the criterion of the minimum heat balance difference and cell voltage, the best cell with 85% current efficiency,0.5A·cm-2 current density,13.27 kW·h/kg·Mg power consumption,32 anodes and 34 cathodes,5.11V cell voltage,0.13% heat difference, the dimension 11.07×7.68×2.65m,0.04m ACD was obtained.