Decarburization Model for Vacuum Degasser

Abstract

A new decarburization model for the vacuum degasser was constructed. In this model, the mass transfer of carbon andoxygen in the liquid phase, the mass transfer of CO in the gas phase and the chemical reaction rate at the interface were taken into account for the rate controlling steps. Also, as the decarburization sites, the Ar bubble surface, bath surface, and the CO bubble formation at inner sites were considered. This model was verified by the correspondence of the calculation results with the experimental results of the small scale tests and applied to the various RH degassers. The following results were clarified :
1) Decarburization at inner sites mainly occurs in the initial stage of the decarburization process (Stage I ), and decarburization at the bath surface becomes predominant in the final stage of the decarburization process (Stage II).
2) The reaction in Stage I is mainly governed by the circulation rate and evacuation rate.
3) The evacuation rate has a smaller influence on the reaction in Stage II. In this stage, it is essential to increase the circulation rate and to increase the effective reaction area for the decarburization at the bath surface by inducing violent surface agitation.