Flow of fine particles entrained by upward gas flow in packed beds of coarse particles

Vertical columns, 1- and 2-m in height, packed with coarse glass spheres or pulverized coke, are used as a cold model for a blast furnace, The effect of bed height on static and dynamic holdups of fines (sieved glass beads, FCC catalyst particles or pulverized coke particles) is investigated using this system, The static holdup of fines is approximately the same in the 1- and 2-m high packed beds, However, the dynamic holdup in the 1-m high packed bed is larger than that in the 2-m high packed bed when glass beads of 65 mu m diameter and FCC catalyst particles are used as the fines. The holdup of fine glass beads is then determined at 0.2-m intervals to the axial direction in the 1-m high bed packed with glass spheres, The dynamic holdup is large in the bottom region of the packed bed and approaches a constant value with increasing distance from the bottom, which explains the increase in average dynamic holdup in the shorter packed bed.