Computational fluid-dynamics simulation of postcombustion in the electric-arc furnace

To obtain insight on the characteristics of postcombustion (PC) inside an electric-arc furnace (EAF), a three-dimensional computational fluid-dynamics (CFD) model was developed. Simulations of the process, including the PC reactions, radiation heat transfer, and de-PC reactions have been conducted. Dissociation reactions of the PC products were also considered in the PC model. The predicted temperatures are realistic because of the inclusion of radiation and the dissociation of CO2. Based on gas/liquid and gas/solid interfacial reaction kinetics, a de-PC reaction model was developed and successfully integrated into the CFD model to simulate the reactions between O-2/CO2 and carbon in the liquid metal, the electrodes, and the scrap. It was found that the de-PC reactions decrease the net heat generated by reactions in the furnace and decrease the PC ratio. The rate of oxidation of the electrodes was also calculated. Radiation was found to be the main heat-transfer mechanism from hot combustion gas to the metal and furnace wall. Under a flat-bath condition, the heat-transfer efficiency is very poor; most of the heat generated by PC is transferred to the furnace wall. When a low-temperature scrap pile exists in the furnace, the heat-transfer efficiency is improved significantly. Air ingress from the slag door significantly decreased the PC ratio and the heat-transfer efficiency.