Resumo

HERLAND, E.V.; SPARTA, M.  e  HALVORSEN, S.A.. 3D models of proximity effects in large FeSi and FeMn furnaces. J. S. Afr. Inst. Min. Metall. [online]. 2018, vol.118, n.6, pp.606-618. ISSN 2411-9717.  http://dx.doi.org/10.17159/2411-9717/2018/v118n6a8.

Many large furnaces used for production of ferroalloys are operated using three-phase alternating current. In such furnaces, there are significant skin and proximity effects caused by induction effects in, and between, the electrodes. Moreover, there may be high currents induced in the furnace steel shell. This causes additional proximity effects between the currents in the electrodes and alloy, and the induced currents in the lining and shell. A numerical study of such effects in realistic 3D geometries of ferromanganese and ferrosilicon furnaces is presented. The models are used to estimate the induced currents in the steel shell as well as accurate alternating current distributions in the material layers within the furnace. Also, the active and reactive power densities within the furnace are studied. The results show that there are strong skin and proximity effects in the conductive material layers within the furnace. Both the electrode proximity effects and the proximity effects caused by the steel shell are computed. The latter can be significant, and should be included when high accuracy is required.

Palavras-chave : ferroalloy furnace; electrical conditions; AC current; current density; skin and proximity effects.

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