Computational Fluid Dynamics Simulations for Understanding and Optimizing the AOD Converter

Abstract

Computational fluid dynamics (CFD) has constantly evolved in the last decades and nowadays play an important role in the design and development of modern steelmaking converters. Although the flow inside the converter is highly complex and comprises many physical phenomena, like chemical reactions, heat transfer, and the flow of gas bubbles in the liquid melt, it is possible to capture major effects for the design of new converters with modern simulation tools. It is well known that the decarburization reaction is strongly influenced by the partial pressure of CO. To ensure a low partial pressure of CO, a flat bath design with low bath height shows advantages. On the other hand, the bath height needs to be sufficient to ensure enough time for the reactions of the rising gas plume with liquid melt as well as proper mixing. Primetals Technologies has used extensive numerical simulations to compare various bath geometries for a 120 t AOD to improve bath mixing and the interaction between slag and steel phase. As a result, an optimized flat bath geometry could be found, which was an intermediate configuration between deep bath and flat bath design that ensures both high mixing efficiency for the reduction phase and low partial pressure for the decarburization phase. In this paper the most important aspects of numerical modelling of the flow and mixing inside an AOD converter are described, followed by a detailed comparison of different vessel geometries and presentation of an optimized version.