Fundamental Mathematical Model for AOD Process. Part I: Derivation of the Model

Abstract

This paper presents a new simulation model for the AOD process that takes the local variations into account but is still computationally efficient. The new idea here was to model AOD reactor as a combination of a plug flow reactor for the plume zone and a continuously stirred tank reactor (CSTR) for the bath and surface slag. This approach adopted has many advantages compared with the previous models. At first, it offers an effective method for considering the locally varying conditions as the gas bubbles rise in the plume. The model can be built computationally very effective compared to CFD due to significantly smaller amount of variables. The validation of the model is also easier as it has features that can be experimentally determined. The model is based on the simultaneous solution of conservation equations of mass, species and energy in all the vertical cells of the plug flow reactor, and a single volume in bath and surface slag. A novel method was developed and used for solving the rates in a mass transfer controlled multi-component reaction system. In this Part I of this paper, the model is presented and its features discussed by few illustrative examples. In the following Part II, the model is broadly validated with new full scale industrial AOD process measurements for carbon release rate, melt composition, slag composition and bath temperature rise during final stages of carbon removal.

Law of Mass Action Based Kinetic Approach for the Modelling of Parallel Mass Transfer Limited Reactions: Application to Metallurgical Systems

“…The studied applications in the AOD process include mathematical modelling of reactions in a single gas bubble in liquid steel, 19) during side-blowing decarburization 20,21) and during the reduction of slag. 22,23) The method has also been applied for mathematical modelling of chemical heating in the CAS-OB process.…”

Modelling of the Refining Processes in the Production of Ferrochrome and Stainless Steel

“…However, the bubble size distribution inside the converter is difficult to measure and therefore the modeller needs to be satisfied with estimated values. By trying different bubble sizes and bubble size distributions, it is possible to adjust the model in order to make it more equivalent with the reality (Järvinen et al, 2011).…”

“…Process models for the AOD converter have been proposed by e.g. Fruehan (1976), Sjöberg (1994), Wei & Zhu (2002), Zhu et al (2007), Wei et al (2011) and Järvinen et al (2011).…”

A Mathematical Model for the Reduction Stage of the AOD Process. Part I: Derivation of the Model

“…Järvinen et al [5][6][7] have presented a process model, which considers mass transfer -controlled reactions and locally varying conditions in the plume zone. This model can be used to describe decarburisation and slag formation during the side-blown decarburisation stage of the AOD process.…”