Three-Dimensional Modeling of an Ironmaking Blast Furnace with a Layered Cohesive Zone
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BLAST furnace (BF) ironmaking is the most important technology for reducing hot metal (HM) from ferrous materials. In modern BF ironmaking, iron ore and coke particles are often charged alternatively into a furnace via a top charging system, forming layered burden structures within the throat. Meanwhile, the oxygen-rich hot air introduced from tuyeres at the lower part creates void zones known as raceways, where the reducing gas resulting from the combustion of coke and pulverized coal is re-distributed before flowing upward. During the burden descent, the ore is reduced and melts in the cohesive zone (CZ), forming liquid slag and iron by the ascending reducing gas. The liquids then percolate through the coke bed in the form of droplets/ rivulets in the dripping zone to the hearth for periodic drainage. To design and operate BFs efficiently and
LULU JIAO, SHIBO KUANG, and AIBING YU 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] YUNTAO LI and XIAOMING MAO are with the Ironmaking Division, Research Institute (R&D Center), Baoshan Iron & Steel Co., Ltd, Shanghai 201900, P.R. China. Hui Xu is with the Ironmaking plant, Baoshan Iron & Steel Co., Ltd, Shanghai 201900, P.R. China. Manuscript submitted June 24, 2019.
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reliably, it is necessary to fully understand these complicated local phenomena and their impacts on BF performance. In the past years, various methods have been developed to study the BF ironmaking process, such as theoretical analysis, dissection studies, in situ measurements, physical experiments and mathematical modeling.[1,2] BFs are operated under an extremely harsh environment, involving intensive interactions among gas, solid and liquid in terms of flow and heat and mass transfer at high temperature and pressure. Therefore, in-furnace states of industrial BFs are extremely difficult if not impossible to access via physical measurements. To some extent, this problem can be overcome using a small experimental BF (e.g., ~ 9 m3 BFs,[3,4]) which in principle functions in a similar way to a real BF. However, it is unaffordable for most investigators to build up, run and maintain such an experimental platform. Moreover, the scale-up issue from experimental BFs to industrial ones has not been fully resolved yet. All these problems can in principle be overcome by numerical modeling and simulation. Numerical BF models, as reviewed by different investigators,[2,5–9] can be discrete or continuum based according to the solid phase and are represented by the discrete element model (DEM) and two-fluid (or multi-fluid) model (TFM), respectively. The latter is solved by traditional computational fluid dynamics (CFD) over computational cells that are larger than particles but still very small compared with process equipment.
Therefore, it is computationally convenient and efficient and has been mainly used to predict the primary phenomena r
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