Circulation rate of liquid steel in RH degassers

Vacuum-decarburization with the Ruhrstahl-Heraeus process is used for the production of ultra-low carbon steels. One important aspect of the RH process is the circulation of liquid steel between the degassing unit and the transport ladle. Thus, supervisory control of the RH treatment requires precise mathematical modelling of the circulation rate. In this work, a numerical model of the circulation flow is described in detail. This newly developed model as well as a frequently used semi-empirical equation are compared with measured data. It is shown that the numerical model is in far better accordance with the measured data than the semi-empirical equation. The numerical model is then applied to data of a conventional RH treatment. Special emphasis is put on the coupling of circulation rate and reaction rate. Both, circulation rate and reaction rate, are calculated as a function of time.