Modeling of fluid flow in tundishes during continuous casting of steel and minimization of transition slabs.

Abstract

As a major component of a continuous caster, the tundish is being recognized as very crucial in continuous casting production. A properly designed tundish can play an important role in improving steel quality and increasing output. Current tundish operation bears two primary tasks: optimization of tundish performance and minimization of transition slabs. Both are closely related to fluid flow and mixing in the tundish. In this investigation, tundish flow and mixing characteristics with various flow controls have been studied through computer simulation. The predicted results have been verified with both physical modeling and in-plant data. New approaches are explored based on the predicted tundish flow characteristics to significantly reduce transition slabs, one of the difficulties in continuous casting production for high productivity and low cost. The results in this study indicate that tundish levels and flow controls critically define tundish performance and chemistry extension during a grade change. Major results of the study are: (1) Tundish configurations critically affect tundish performance. Conventional baffles and weir/dam combinations are generally beneficial to tundish flow. However, tundish flows with baffles are relatively more sensitive to tundish levels than with weir/dam combinations. (2) Multiple weir/dam combinations can significantly improve tundish flow and dramatically reduce chemistry mixing in the tundish. On the other hand, baffles could not be used to substantially reduce mixing during grade changes. (3) Even more important for the extent of mixing than tundish configuration is tundish level operation. Draining a tundish to a lower level and keeping it for the entire transition period can more effectively reduce transition slabs than just lowering the tundish level and then rapidly raising the level. Therefore, depending on casting conditions, the tundish level should be kept as low as possible during the entire concentration transition period.