An Integrated Mathematical Model for Ironmaking Blast Furnace
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ST furnace (BF) ironmaking is the most important technology by which pig iron is reduced from ferrous materials. As an energy-intensive process, the BF ironmaking process, together with the associated units (e.g., pelletizing–sintering machine and coke oven), represent approximately 70 pct of the total energy input into an integrated steelwork and contributes approximately 90 pct of the total CO2 emission. Therefore, it is necessary to optimize the BF ironmaking process for minimizing fuel consumption and mitigating CO2 emission, which becomes particularly important under increasingly demanding and tough economic and environmental conditions. To achieve this goal, the heat exchange and chemical reactions between different LINGLING LIU, BAOYU GUO, and SHIBO KUANG are with the ARC Research Hub for Computational Particle Technology, Department of Chemical Engineering, Monash University, Clayton, VIC 3800, Australia. Contact e-mail: [email protected] AIBING YU are with the ARC Research Hub for Computational Particle Technology, Department of Chemical Engineering, Monash University and Center for Simulation and Modeling of Particulate Systems, Southeast University-Monash University Joint Research Institute, Suzhou Industrial park, Jiangsu 215213, P.R. China. Contact e-mail: [email protected]. Manuscript submitted March 31, 2020.
METALLURGICAL AND MATERIALS TRANSACTIONS B
phases need to be effectively controlled in every region or zone of a BF. In this direction, understanding the in-furnace states and the resulting overall performance of BF under different conditions is important. BF is a high-temperature and high-pressure moving bed reactor, in which the counter-, co-, and cross-current flows of gas, liquid, solid, and powder interact strongly, coupled with the heat and mass transfer and chemical reactions. In routine operations, the burden materials that consist of iron-bearing ore and coke with flux are alternately charged into the top of a BF. Meanwhile, the oxygen-rich hot air and pulverized coal (PC) are injected into the BF through tuyeres near the bottom, forming a cavity known as the raceway. In the raceway region, PC and coke combust with hot air, generating reducing gases and smelting heat. During the burden descent, the ore is reduced and heated by the ascending gas before it melts in the cohesive zone (CZ) forming liquid slag and iron. The liquids then percolate through the coke bed to the hearth and are periodically drained out through a taphole. The coke bed in the hearth may float in the hot metal (viz. floating coke bed), rest on the refractory pad near the middle of the hearth (viz. sitting coke bed with coke free gutter), or fill the hearth completely (viz. sitting coke bed), leading to different liquid flow behaviors.
Because of the complexity of BF, it has been a challenge to access the above in-furnace phenomena by means of physical experiments and/or in-suite measurements. Numerical models can in principle overcome this problem and have the merits of high efficiency and low cost while providing some
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