Hydrodynamics of slot‐rectangular spouted beds: Effect of slot configuration on the local flow structure

Abstract

The local flow structure in a slot-rectangular spouted bed column of 300 mm × 100 mm cross-section was investigated with slots of equal area but different length-to-width ratios. Dead-zones, spout shapes, and distributions of pressure, particle velocity, and voidage were explored. The local flow structure of the slot-rectangular spouted bed became similar to conventional spouted beds as the height increased, with spouts from slots of different length-to-width ratios approaching similarity in the upper part of the bed. Static bed height was found to have little influence on the flow in the spout at a given level.On aétudié la structure d'écoulement local dans une colonneà lit jaillissant rectangulaireà fentes d'une section transversale de 300 mm × 100 mm, les fentesétant de surfaceégale mais les rapports longueur sur largeur différents. Les zones mortes, les formes de bec et les distributions de pression et de vitesse des particules ainsi que le degré de vide ontété explorés. La structure d'écoulement local du lit jaillissantà fentes rectangulaires devient semblableà celle des lits jaillissants conventionnels lorsque la hauteur augmente, les jets des fentes de différents rapports longueur sur largeur approchant une similarité dans la partie supérieure du lit. On a trouvé que la hauteur de lit statique avait peu d'influence sur l'écoulement dans le jetà un niveau donné.

Stability of slot‐rectangular spouted beds with multiple slots

“…Unlike the regimes for single slot spouting, [6] swaying in random directions was also found in Column B with two or three slots in-series, that is arrangements c or d. However, there was a tendency for fountains to sway together or 180°out of phase at a frequency of $2 Hz, similar to that for swaying with a single slot. [6] At this stage, the flow of multiple spouts was similar to that reported [20,22] for multiple spouted beds with square plenum chambers and central circular gas inlets, where the flow was stable and steady, close to the minimum spouting velocity.…”

“…As portrayed in Figure 8, the pressure fluctuation and power spectral density (PSD) lines are similar to those for steady state spouting. [6] Merging of spouts also occurred in For aligned slots, the fountains tended to avoid overlap with other fountains. They always moved to, and stayed at, a random asymmetric position.…”

“…Static bed heights of up to 600 mm (at which height, a spouting in fluidised bed regime was found by previous tests for single-slot spouting [6] ) were tested in this work. Although the slots were identical, multiple spouts from these slots did not appear at the same overall gas flow.…”

Assessment of static bed height and particle diameter on the hydrodynamic behavior of a spouted bed

“…The scale-up of such columns has been suggested to be easily achieved by increasing the thickness [4]. However, three-dimensional instabilities have been shown as an issue for scale-up [8,9]. Slot-rectangular spouted beds can be utilized in similar applications as those proposed for conventional spouted beds.…”

“…However, investigations on the application of slotrectangular spouted beds have been mainly limited to the coating of particles. Numerous studies on the flow hydrodynamics, stability and scale-up of slotrectangular spouted beds have been reported [3][4][5][6][7][8][9][10][11][12][13].…”