Mathematical Modelling of Basic Oxygen Steel Making Process

Abstract

A numerical model based on reaction the rmodynamics has been developed to simulate basic oxygen steel making process for predicting hot metal composition inside Linz-Donawitz (LD) converter with respect to blowing time. This mode l also contributes to-wards the prediction of sloping phenomenon taken place during basic oxygen steel mak-ing process. Modelling of basic oxygen steel making process has significant utility as productivity and lining life of Basic Oxygen Steelmaking(BOS)is highly dependable upon mass, momentum, energy transfer and rigorous interaction among metal,slag and gaseous phases. Comprehensive thermodynamic model of basic oxygen steel making pro-cess has been developed to predict the bath composition and temperature as well as de-carburization rate dynamically based on relevant blowing process parameters. One of the striking features of this developed model is the first time prediction of temperature vari-ation depending on evolving bath composition and generated heat from bath composition dependent feasible reactions and their extent. Moreover, this numerical model does not require off gas analysis to maintain its dynamic nature of prediction. A true attempt for the benefit of steel industry is made for predicting slopping initiation time for particular blowing condition based on correlation with model predicted decarburization rate and critical decarburization rate for bloating of metal droplet. In connection to that, formation of foamy slag and sloping possibility have been studied using thermodynamic modelling followed by multiphase computational fluid dynamics (CFD) simulation technique. The CFD simulation has been carried out taking different turbulence models along with vol-ume of fluid method (VOF) using ANSYS 15.0 software. CFD work demonstrates change in bath deformation profile during blowing period and also identifies the locations of dif-ferent vortexes formed owing to supersonic oxygen jet penetration. Dynamic mathemat-ical model of BOS has been interconnected with CFD simulation work for correlating fluid flow parameters with reaction behaviour inside BOS furnace. The results of devel-oped model has been comparedand validated with plant data. This work actually helps to understand basic oxygen steel making process in detail during the blowing period. De-veloped dynamic model can be used for LD converter having different capacities and accordingly this model’s application is very significant and wide in primary steel making area