The Behavior of Suspended Solid Particles in the Bubble Column

Abstract

The behavior of suspended solid particles in the bubble column was experimentally studied.

Particle suspension in (air-agitated) pachuca tanks

“…Studies in FAL bubble columns, [13] however, showed that critical air velocity increased with tank diameter. This observation is in conformity with Imafuku et al [9] and Smith et al, [14] but is opposite to that reported by Hallett et al, [6] Roy et al, [8] and Furchner and Mersmann. [12] Bubble columns differ from Pachuca tanks (Table I) both in terms of dimensions and mode of operation.…”

“…Perhaps the most rigorous investigation of particle suspension in bubble columns is by Koide et al [7] They observed that the critical air velocity for off-bottom suspension was lower in tanks with a conical bottom, which was also reported by Imafuku et al [9] The FCC configuration was found to be more efficient in suspending particles than the FAL configuration. Experimental observations revealed that the critical gas velocity was at a minimum at a D d /D t ratio of 0.6.…”

“…These are (1) visual observation, [8,[13][14][15]20] (2) slurry sampling, [8,14] and (3) pressure measurements. [7][8][9]13,20] Particle suspension in the present investigation has been characterized by visual observation.…”

“…Critical air velocities can be measured in two ways, either by ''generating'' [15] (starting with settled solids) or ''maintaining'' [9,10] (starting at air velocities much greater than that required for complete off-bottom suspension) suspensions. There is a possibility that the ''two'' critical air velocities may be different (hysteresis).…”

“…[6] is that industrial tanks operate at superficial air velocities considerably lower than those required for off-bottom suspension in their experiments. Several investigations on particle suspension have been carried out in bubble columns both in the presence [7] and absence [8][9][10][11][12][13][14] of a draft tube. Many of these investigations have been summarized by Abraham et al [15] Because bubble columns are similar in configuration to Pachuca tanks, some important conclusions emerging from bubble column studies are presented subsequently.…”