Gas‐Liquid mass transfer in a three‐phase fluidized bed with floating bubble breakers

Abstract

The effects of liquid and gas velocities, particle size and volume ratio of floating bubble breakers to solid particles (V,/v,) on both the volumetric mass transfer coefficient, k,a, and the gas-liquid interfacial area, a, have been determined in three-phase fluidized beds with floating bubble breakers. Beds having a volume ratio (V,/V,) of about 0.15 showed a maximum increase in both k,a and a of about 30% in comparison to that in the corresponding bed without floating bubble breakers. The volumetric mass transfer coefficient in three-phase fluidized beds with or without tloating bubble breakers can be estimated from the surface renewal frequency of liquid microeddies and the particle size. a 7 On a dktermint dans des lits fluidisis triphasiques munis de rupteurs de bulles flottantes les effets de la vitesse du gaz et du liquide, le rapport entre la taille des particules et le volume des rupteurs de bulles tlottantes et le coefficient de transfert de matikre, kp, ainsi que la surface interfaciale gas-liquide, a. Les lits ayant un rapport de volume (V,lv,) d'environ 0,15 montrent une augmentation maximale B la fois dans kp et a d'cnviron 30% par cornparaison a celle du lit corrcspondant sans rupteurs de bulles flottantes. Le coefficient volumetrique de transfert de rnatibre dans les lits fluidises triphasiques avec ou sans rupteurs de bulles flottantes peut itre estimC Zi partir de la frkquence de renouvellement dc la surface des micro-tourbillons liquides et la taille des particules.

Volumetric Mass Transfer Coefficient in non‐Newtonian Fluids in Spout Fluid Beds

“…This is in good agreement with the value obtained in a spoutfluid bed [25] using a non-Newtonian fluid where a value of 0.84 was reported. This is also in qualitative agreement with the dependence on liquid velocity in three phase fluidized beds [24] where they have reported a value of 0.45 whereas others have reported a value of 0.42 [10]. This is also qualitatively similar to the values reported by other authors in bubble columns [31±33].…”

Hydrodynamics and Mass Transfer in Gas‐Liquid‐Solid Circulating Fluidized Beds

“…Assuming liquid axial dispersion is negligible, the plug-flow model [3] (PFM) is generally applied to determine k L a in the distributor (grid zone) of fluidized beds. The axial dispersion model [9] (ADM) improves the PFM by considering liquid dispersion in the axial direction, and thus a certain degree of back-mixing has been taken into account. Alvarez-Cuenca et al [4] observed two well-differentiated mass transfer zones in three-phase fluidized beds with poor mixing in the grid zone but very high mixing in the bulk zone.…”

Gas-liquid mass transfer in bioreactor with three-phase inverse fluidized bed

“…Te¯on was used because of its low contact angle with water, hence easier bubble attachment from the sparger ori®ces, low coalescence and small bubbles. Filtered air from the compressed air mains, or nitrogen from a 99.99% purity grade gas cylinder were delivered to the gas distributor through a Gilmont¯owmeter (8). The circulation lines were equipped with globe valves (10), facilitating the experiments and the column had an overow outlet (14) used for adjustment the level of the threephase¯uidized zone.…”