Computational analysis of a twin-electrode DC submerged arc furnace for MgO crystal production

Abstract

A twin-electrode DC arc furnace has been designed for MgO crystal production and this technique has been found to be another effective method to grow high quality MgO single crystals. Compared with AC submerged arc furnaces, the benefits of DC furnaces are significant. However, the magnetohydrodynamic effects might inhibit the growth of large single crystals. In order to understand the process we present a three-dimensional numerical model of the DC furnace. Coupled with Maxwell's equations, the conservation equations for mass, momentum, and energy are solved with ANSYS. It is found that the shape of the melt–solid interface is significantly affected by the electromagnetic stirring, and the predicted shape of the molten bath shows good agreement with the experiments. It is observed that the environment is more suitable for the crystal growth between each electrode bottom and the shell. These interesting phenomena may be caused by the variation of the flow field which is quantitatively described in the model. Other detailed information including the electric power and the voltage drop distribution is also given approximately by the model to give decision support for the power control system.