Three-Dimensional Modeling of Flow and Thermochemical Behavior in a Blast Furnace
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THE blast furnace (BF)—basic oxygen furnace process remains the predominant route of steel production, accounting for over 60 pct of global steel output, although the challenges from new ironmaking processes continue. In an integrated steel plant, the ironmaking BF is the main energy consumer, accounting for nearly 70 pct of the whole plant.[1–3] The practice of a BF is schematically shown in Figure 1, where the solids of coke and ore etc. (termed burden) are charged from the furnace top; the high temperature, high velocity air (termed blast) is introduced into the lower part of the furnace via tuyeres, forming void zones (termed raceways) and combusts coke to generate reducing gases and smelting heat. As the solids (mainly coke and ironbearing materials) travel downward and reducing gas goes upward, the latter together with smelting heat reduces and melts the iron-bearing burden to form liquid iron and slag in the so-called cohesive zone. The liquids then percolate through the coke bed (termed as dripping zone) to the hearth. In some cases, the injection of pulverized coal may be practised for operational and
YANSONG SHEN, Research Fellow, and AIBING YU, Professor, are with the Department of Chemical Engineering, Monash University, Clayton, VIC 3800, Australia. Contact e-mail: yansong. [email protected] BAOYU GUO, Research Fellow, is with the School of Materials Science and Engineering, The University of New South Wales, Sydney, NSW 2052, Australia. SHENG CHEW and PETER AUSTIN, Principal Research Engineers, are with the Steelmaking Technology and Planning, BlueScope, PO Box 202, Port Kembla, NSW 2505, Australia. Manuscript submitted January 16, 2014. METALLURGICAL AND MATERIALS TRANSACTIONS B
cost benefits.[4–6] Physically, a modern BF is a hightemperature moving bed reactor, involving counter-, co- and cross-current flows of gas, liquid and solid flows, and heat exchange and chemical reactions.[1,7] It is very challenging but important to understand the complex infurnace phenomena of gas–solid–liquid flow and thermochemical behavior, including the circumferential multiphase flow in the vicinity of raceway, and key process indicators, for operational control and optimization in BF practice. The operation of a BF is usually investigated for two related purposes, viz. to predict process indicators and more importantly, to understand internal state of a BF. The two aspects can be studied by different methods including industry-scale investigations, lab/pilot-scale experiments, and mathematical modeling. The industryscale investigations are normally conducted for measuring the process indicators such as gas utilization rate at furnace top, and for understanding the internal state to a certain degree by means of techniques such as dissection[8] and tuyere core drilling,[9] but they are difficult in implementation due to, for example, the need of a BF stoppage and the high cost. Lab/pilot-scale experiments are also used for understanding the internal state of BF operation, for example, by use of an experimental BF in LKAB,[10
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