Modeling of Scrap Heating by Burners

Abstract

<p>The efficiency and productivity of Electric Arc Furnace steelmaking has improved with a number of new technologies. One of these is the use of oxy-fuel burners to assist the electric heating. Initially burners were just used to melt the scrap at the slag door where arc heating is inefficient. At present virtually all modern EAF use oxy-fuels burners to decrease electric energy consumption and increase productivity. Despite the impressive performance of these burners there is little information on the efficiency of the heat transfer between the combustion gas and the steel scrap in the furnace. The purpose of this research was to measure and model the heating efficiency for a range of scrap types. The ultimate goal of this study is to assist operators with the selection of energy inputs and scrap grades from different sources, so as to optimize the operation.</p> <p>Experimentally, steel scrap heating phenomena were studied using an oxy-fuel burner in a small scale furnace (1m3) for a range of burner power, scrap type and furnace configuration.</p> <p>An in-house computer model was developed, considering non-uniform porosity inside the furnace, turbulence, dynamic behavior of porosity due to localized melting. The model was tuned using the experimental data of scrap heating by oxy-fuel burners in a small-scale furnace (1 m3). Due to lack of literature of porous media fluid flow and heat transfer for irregular shaped particles and complexity of the problem a detail analysis and considerations of the model parameters e.g., porosity variation inside the furnace, permeability of the bed, drag coefficient of the bed, effective thermal conductivity of the bed, fluid to solid heat transfer coefficient and radiation inside the bed, were performed. Model parameters were dependent upon porosity of the bed and characteristic particle diameter. Sensitivity analysis was performed to study the effectiveness of heating with model parameters. Measured porosity variations were used for numerical simulation and characteristic particle diameter for different scrap was tuned to match the experimental results with numerical simulation. Thermocouple temperatures were also modeled since it was between the gas and solid temperatures. Using tuned characteristic particle diameter simulations were performed for different scrap with different furnace configuration.</p> <p>Experimental and numerical modeling results were used to analyze heat transfer and fluid flow phenomena during scrap heating by burners. This appears to be the first time a numerical model for heat transfer between flame and scrap was developed and validated with experimental data.</p>