Application of electromagnetic forces to reduce tundish nozzle clogging

This paper considers the problem of oxide build-up within a tundish nozzle when casting aluminum killed steel. Water model studies have shown that the clogging problem may be very dependent on the flow pattern in the nozzle entry region. In particular, the studies show that the flow can separate within the entrance region of the nozzle, leading to the development of a stagnation zone that can trap oxide particles. This paper proposes that the stagnation zone can be substantially reduced, if not eliminated, through the use of electromagnetic forces. To generate the required electromagnetic force, two systems are considered. The first is based on injecting a DC current; the second by using electromagnetic induction. Both methods are described in this paper. Order of magnitude calculations are provided to illustrate that both methods are essentially feasible. The performance of each method in terms of modifying the turbulent flow characteristics in the nozzle entry region is then examined using a numerical model. It is shown that both methods can greatly reduce the recirculation zone. A cylindrical nozzle was chosen for the model studies since it represents a worst case situation. On the basis of the model studies, it can be concluded that whereas both of the proposed methods have the potential to reduce the troublesome recirculation zone, the induction method appears to be simpler in terms of practical implementation. (C) 2003 Elsevier Inc. All rights reserved.