2020 Volume 60 Issue 12 Pages 2669-2677
Raceway zone is one of the most important regions in blast furnace, since it governs efficiency and stability of the blast furnace process through combustions of coke and auxiliary reducing agent, burden descent, fines generation, and so on. Therefore, quantitative understanding of the raceway behavior is indispensable to designing and realizing highly efficient operation of blast furnace. In the raceway, a cavity is formed and the coke particles circulate due to interaction between particles and high velocity blast gas, and consumption of coke. Thus, two-phase flow behavior is one of the key features of the raceway formation. In this study, the formation behavior of the raceway in the isothermal and non-reactive packed bed was numerically discussed from the viewpoint of two-phase flow. The mathematical model used in this study consisted of Lagrangean particle tracking method and Eulerian computational fluid dynamic technique, and these were combined through voidage distribution and momentum exchange. This model was applied to a small-scale cold-model condition. The simulation results revealed the raceway formation behavior such as variations of cavity size, particle motion, gas flow field, and contact force network. Furthermore, the effects of the initial packing structure on the raceway formation, the differences in the raceway formation behavior in the fixed bed and the moving bed and their mechanisms were clearly elucidated.
