Mathematical modeling of postcombustion in a KOBM converter

A mathematical model has been developed to describe gas flow, combustion reactions, and heat transfer in converter-type steelmaking processes. Thek- ε two-equation turbulent model, a finite reaction model, and the DeMarco-Lockwood flux model have been incorporated in this model to deal with the turbulent flow, postcombustion reactions, and radiation heat transfer. Local gaseous flow patterns, temperature, and heat flux distributions were calculated for a 300 tonne Klöckner Oxygen Blowing Maximillanshuette (KOBM) converter. Comparison between the heattransfer fluxes calculated based on the model and those measured industrially indicates the validity of the model in this application. The postcombustion has been found to be determined by the decarburization rate (DCR) which is directly related to the hardness of blowing not by the entrainment of surrounding gas to the oxygen jet as previously reported. The model revealed that about 20 pct of what is normally considered to be recovered heat has actually been lost through the vessel wall and to the lance. It is shown that this model is useful in studying the detailed mechanisms of postcombustion to optimize operations in converter-type steelmaking processes.