A Detailed Single Bubble Reaction Sub-Model for AOD Process

Abstract

A new detailed model that describes the chemical reactions, mass transfer and heat transfer taking place on the surface of a single gas bubble in liquid steel is presented in this paper. By using this model, locally occurring small scale physical and chemical mechanisms can be effectively studied. This information is required later in developing a simplified reaction sub-model to be used in CFD simulation of an operating AOD vessel. To demonstrate the capabilities of the new model, the behaviour of a single bubble under two example conditions was simulated. In the case of high carbon content of the steel, here 1%, a contribution analysis showed that the major fraction of the oxygen goes to oxidize dissolved C. When 50% of the carbon in the bath is burned and if the same gas composition (90% O2, N2) is still used, the main product is initially Cr2O3, indicating that the gas composition should have been changed if this had been a real process in question. To verify, a series of O2/N2 ratios 0.1…0.95 were simulated at 50% C conversion to see how more optimal product yield can be obtained. In addition, time dependent profiles of temperature and all species in and around the bubble are presented. The results presented here are applicable only to a local position in the AOD vessel. To be applicable to a whole AOD vessel, the model should be implemented as a source term into CFD software or a corresponding process simulation tool. This will be our future work.