Heat Transfer Analysis of Lance Skulling in Top Blown Oxygen Steelmaking converters

Abstract

The lance used for blowing oxygen in top blown oxygen steelmaking converters (BOF) is water-cooled. Deposition of metal on the lance surface results in an increase in the diameter and mass of the lance. If the deposition (skulling) is excessive, it may cause severe operational difficulties in taking out the lance from the vessel after the blow is over. The temperature difference of inlet and exit cooling water circulating inside the lance is a direct measure of the condition of the lance. An iterative calculation procedure using a computer program has been developed, for the case of a lance used in a 100T vessel, to study the effect of solidification of molten metal (skulling) on the lance body on the exit water temperatures. For the first time, the effect of radiation from hot spots has been taken into account and it turns out to be the most significant factor in heat transfer.