Modelling of a continuous casting mold level control system with emphasis on the pouring conditions in the submerged nozzle

This paper presents an extension of the published work by N. Kiupel et al. [1], based on project studies at the Gerhard-Mercator-Universität Duisburg in cooperation with the company HKM in Duisburg. It focuses on a subsystem of the original model considered by N. Kiupel et al. of the mold level control system. This subsystem contains the supply vessel, the submerged nozzle and the mold under different flow conditions. Two possible flow conditions are distinguished: steel casting with a continuous mass flow and steel casting with an interrupted mass flow. The reason for this distinction is that during the operation under different pouring conditions, oscillations with unknown causes occur. It is suspected that these oscillations are caused by different flow conditions in the submerged nozzle. In the first case it is assumed that the liquid steel flows in a continuous stream through the submerged nozzle, so that there is a direct mass and force connection between the supply vessel and the mold. In the second case it is assumed that the flow is interrupted and the space in between is filled with gas. The remaining part of the model has been taken from the complete model described in the literature [1]. For better understanding of the model and its function the subsystem is described within the context of the whole system, and the effects of the force connection will be illustrated by simulation results.