Optimization of Steelmaking Processes in an Electric ARC Furnace
Abstract
The Electric Arc Furnace is being used quite frequently and significantly in today’s environment due to its energy saving and improved product quality features. It is even more important to study more about optimizing the processes involved in the EAF in order to capitalize on its positive features and thus able to contribute to the world in our bid to fight global climate change. During the refining stage of the Electric Arc Furnace (EAF) operation, molten steel is stirred to facilitate steel/slag reactions and the removal of impurities, which determines the quality of the steel. The stirring process is driven by the injection of oxygen, which is carried out by burners operating in lance mode. In this study, a computational platform is used to analyze the flow dynamics produced during the stirring of the steel bath in an industry-scale EAF. Namely, nonreacting, three-dimensional, transient simulations of the liquid bath stirred by oxygen injection are carried out to analyze the mixing process. The CFD domain includes the liquid bath and the oxygen injected by three coherent jets. The study includes a baseline case, where the oxygen is injected at 1000 SCFM in all the burners. Two sets of cases are also included: first set considers cases where oxygen is injected at a reduced and at an increased uniform flow rate: 750 and 1250 SCFM, respectively. Second set considers cases with non-uniform injection rates in each burner, which keep the same total flow rate of the baseline case, 3000 SCFM. The analysis is also quantified by defining two variables: the mixing time and the standard deviation of the flow velocity. Results indicate that the mixing rate of the bath is determined by flow dynamics near the injection cavities, and that the formation of very low velocity regions or ‘dead zones’ at the center of the furnace and at the balcony regions prevent the flow mixing. All the non-uniform injection cases reduce the mixing time obtained in the baseline case. The melting of HBI/scrap in an electric arc furnace (EAF) is studied by using a computational fluid dynamics (CFD) platform. A previously developed scrap melting model is extended to investigate the different physical phenomena involved in melting of HBI/scrap charges. The CFD platform merges three computational models, namely a scrap/HBI melting model, an electric arc model and a coherent jet model. The simulation conditions were selected to match those typically seen in industry-scale EAFs.
Degree
M.Sc.
Advisors
Zhou, Purdue University.
Subject Area
Climate Change|Chemistry|Energy|Fluid mechanics|Industrial engineering|Materials science|Mechanics|Thermodynamics
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