回旋区深度对上部炉料运动影响的模拟分析

冶炼实践已证实,高炉回旋区形状和大小影响上部炉料的运动,进而影响煤气流分布及煤气利用率。已有研究多集中在回旋区形状、大小与高炉生产指标的关系,对相关影响机理和规律较少有深入分析。针对此问题,建立二维狭槽半高炉模型,采用离散单元法(DEM)对回旋区深度与炉料形态、混合程度、径向矿焦比的关系进行数值模拟探索。模型中考虑了炉料颗粒在下降过程中的粒度变化,利用离散单元法-计算流体力学(DEM-CFD)耦合方法得到料柱孔隙率分布特征。结果表明,随着回旋区深度增加,料批下降趋向均匀,料层倾斜程度减小,块状带下部炉料混合程度减小;随着料批的下降,矿石相对于焦炭逐渐向中心偏移,回旋区深度对料批径向矿焦比分布无明显影响;块状带整体孔隙率随回旋区深度增加而减小,变化幅度在2.1%左右;回旋区深度较大时,软熔带会有孔隙率较高的区域(较宽焦窗)。

Simulation analysis for influence of raceway depth on upper burden movement

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).