Electrical Scale-Up of Metallurgical Processes

Resumo

The problem under investigation iselectrical scale-up of a generic metallurgicalprocess for primary metal production. In themetal producing step a slag is heated by electriccurrent, typically supplied by an AC three-phasesystem. The system is described by Maxwell’sequations. These equations are analyzedrevealing that the properties of the solution isdetermined by the parameter ( ), where L isthe linear size of the system and is the skindepth. The skin depth is a measure of howdeeply the current penetrates a conductor. Theeffect of changing ( ), needs to beconsidered for scale-up. For cases where a DC approximation is appropriate. 2-dimensional AC simulations have beenperformed. They show unreasonably strongproximity effects, in accordance with theoreticalconsiderations. Such 2D computations shouldtherefore not be applied to get insight for 3Dproblems. COMSOL simulations are applied todemonstrate the theoretical analysis. Comparisonbetween 2D and 3D simulations clearly showsthe strong proximity effect in 2D while it isnegligible for the 3D case. Finally, we haveapplied COMSOL Multiphysics to show how thecurrent distribution for a three-phase system isaffected by scale-up. The results agree well withthe theoretical prediction. Based on our studieswe can conclude that COMSOL Multiphysics isa proper tool for numerical studies of electricalscale-up for metallurgical reactors similar to theones considered.