Simulation of oxygen penetration and decarburisation in EAF using supersonic injection system

The supersonic jet generated by a Laval nozzle in air or in steel has been modelled to vary degrees of complexity and with different goals.(1,2)) This paper describes the application of our model to an injection system based on fixed lances, placed in the furnace walls without the help of CFD simulation, which is certainly very precise, but very time consuming and useless for an on line control. The approach followed here is energy-based and it allows estimating the depth reached by the O-2 during its penetration within the slag and steel. It can be used for an on line control and for the whole description of the injection process. The calculation of a theoretical interface surface allows investigating the chemical process and the mass transport phenomena induced by the injection itself. This simulation can be used to investigate the required injection parameters to ensure the maximum mass exchange with the bath and to foresee new injection technologies performances. Moreover, this model of the supersonic injection allows the construction of a decarburisation model that can evaluate the effects and the efficiency of the injection technology. This article describes the jet-penetration model and the decarburisation model. The validation of the model has been performed by the comparison with the experimental data of the Tenaris-Dalmine EAF and the KT Supersonic Injection System (the chemical package of Techint Technologies for the multi-point injection of oxygen, carbon and other fines into the EAF).