Abstract:Smelting practice has confirmed that the shape and size of blast furnace raceway affect the movement of upper burden, and then influence the gas flow distribution and gas utilization. Most of the previous studies are focused on the relationship between the shape and size of raceway and production index of blast furnace, and in-depth analysis regarding the governing mechanisms has yet to be conducted. To solve this problem, a two-dimensional slot half blast furnace model was established, where the relationships between raceway depth and burden profile, mixing extent and radial ore-to-coke ratio (O/C) were numerically simulated by discrete element method (DEM). In the model, the size variation of particles in the descending process was considered, and the distribution characteristics of burden voidage were obtained by coupling method of discrete element method and computational fluid dynamics (DEM-CFD). The results show that with the increase of the raceway depth, the descent of burden batch tends to be uniform, the inclination of burden layer decreases, and the mixing extent of burden in the lower part of lumpy zone decreases. With the descent of burden batch, the iron ore is more apt to shift towards the center compared to coke, and the depth of raceway has no obvious effect on the radial O/C distribution of batch. The overall voidage of the lumpy zone decreases with the increase of raceway depth, and the variation range is about 2.1%. When the raceway depth is large, the cohesive zone tends to have regions with high voidage (relatively wide coke windows).
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