Evaluation of the Temperature Regime of the Rods of the Inductor of an MHD Stirrer for Possible Use in an Industrial Aluminum Furnace

摘要

In the production of aluminum alloys, the melt must be stirred in the bath of a furnace. For this purpose, it is convenient to use MHD stirrers. However, MHD stirrers that are used in production in practice are mainly linear traveling-field inductors, which cannot be sufficiently effective because of their design features. Their size is much smaller than the linear dimensions of the bath, and the poles of their magnetic circuits are outside the bath walls and the insulation layer; therefore, the traveling magnetic field that influences the molten metal is significantly reduced. For this reason, the electrical power consumed by these MHD stirrers is high (hundreds of kilovolt-amperes). A device in the form of a system of rods (buses) connected in parallel to a three-phase power network and placed in close proximity to the molten metal immediately under the bottom of the bath may be an alternative to these stirrers. The main problem associated with this device is the cooling of rods via the removal of the Joule heat that is released during the passage of an electric current in the rods and the heat received from the molten metal in the bath in the furnace. The simplest way to withdraw the released heat is the convective movement of air in the tubular rods (it is not necessary to use special additional equipment). When conducting multivariant engineering calculations in designing such devices, it is necessary to determine the values of a cooling convective air flow in the hollow rods of the inductor of an MHD stirrer. In the present paper, we propose a numerical calculation of the temperature field in the aluminum furnace and a simple model for the convective air flow that passes through the rods of the inductor of an MHD stirrer. Based on this model and using the results of the physical experiments performed in this study, a simple semiempirical engineering formula for the approximate computation of the convective air-motion velocity in the hollow rods of an MHD stirrer is derived.