基于DEM法的竖炉螺旋排料机对物料下行速度的影响

Influence of screw discharging machine of shaft furnace on particle descending velocity based on DEM method

位于直接还原竖炉底部的螺旋排料装置直接影响着炉料的下行速度,进而影响直接还原的反应进程及得到的海绵铁的金属化率。为了得到类似活塞流的炉料下行速度,本文利用离散单元软件EDEM建立了六种改变螺旋叶片直径和螺距的螺旋排料机模型。结果显示:缩小螺距虽然能使炉料下行速度沿着竖炉径向分布变得更加均匀,但其影响程度没有缩小螺旋叶片直径大。当最小片螺旋叶直径为500 mm时,炉料下行速度分布近似为一条水平线,但此时竖炉中心炉料下行速度过慢,容易增大死料堆的高度,故综合考虑竖炉的实际生产,在本模型中螺旋叶片的最小直径应不小于600 mm。

The helical discharging device located at the bottom of the DRI shaft furnace has a direct influence on the particle descending velocity and on the reaction process of direct reduction and the metallization rate of sponge iron.In order to obtain the descending velocity of charge similar to piston flow,six kinds of helical discharging machine models with varying screw blade diameter and pitch are established by using discrete element software EDEM.The results show that although reducing the pitch can make the downward velocity of the furnace more uniform along the radial distribution of the shaft furnace,the influence is not as large as that of reducing the diameter of the spiral blade.When the diameter of the minimum spiral blade is 500mm, the downward velocity distribution of the charge is of approximately a horizontal line,but the descending speed at the center of the shaft furnace is too slow at this time,and it is easy to increase the height of the dead material piles.Therefore,considering the actual production of the shaft furnace,the minimum diameter of the spiral blade in this model should not be less than 600mm.