G.R. Rigby

Bio: G.R. Rigby is an academic researcher from National Research Council. The author has contributed to research in topics: Bubble & Fluidization. The author has an hindex of 1, co-authored 1 publications receiving 67 citations.

Three-phase fluidization: Some knowledge gaps

Abstract: The most recent review by ostergaard — on the fluid mechanics of three-phase fluidized beds — is updated and broadened, and the more manifest knowledge gaps are identified. A systematic classification of the various modes of three-phase fluidization is presented in order to provide some perspective on the research which has been done and on that which has yet to be done. On a mis a jour et elargi la revue de litterature la plus recente, effectuee par ostergaard, sur la mecanique des fluides des lits fluidises a trois phases; on a ainsi identife les trous de connaissance les plus manifestes. On presente une classification systematique des divers modes de fluidisation a trois phases, afin de mettre en perspective la recherche deja faite et celle qu'il reste a faire dans ce domaine.

Hydrodynamics of Bubble Column Reactors at High Gas Velocity: Experiments and Computational Fluid Dynamics (CFD) Simulations

Abstract: This paper focuses on the modeling of flow and mixing in a bubble column reactor operated at high gas velocities (up to 0.40 m/s). A dual-tip conductivity probe was used to measure local void properties such as local time-averaged gas holdup, chord length distribution, bubble velocity distribution, and interfacial area. Chord length distribution was converted to bubble size distribution, using the backward transformation method. Liquid-phase mixing time measurements were conducted using a conductivity probe. A computational fluid dynamics (CFD) model was developed to simulate the unsteady gas−liquid flow in a bubble column using commercial code FLUENT 6.2. The time-averaged flow properties predicted by CFD simulations were compared with the experimental data. The role of unsteady flow structures in mixing was studied. The “multiple snapshots” approach was used to simulate the mixing time using CFD. The mixing times that were predicted for all superficial gas velocities compared favorably to the measured v...

Phase holdup characteristics of three phase fluidized beds

Abstract: The individual phase holdups in two (liquid-air, liquid-solids) and three (liquid-air-solids) phase fluidized beds have been measured over a wide range of liquid and gas velocities. Ex-periments were canied out in a large two-dimensional bed. Three solids were used ranging in size from 1 to 6 mm. The effect of viscosity (1-70 cp) was determined using solutions of sugar and carboxymethyl cellulose of different concentrations. Various acetone-water mixtures were employed to examine the effect of surface tension in the range 40-73 dyne/cm. Beds of particles having a minimum fluidizing velocity in the liquid of less than 1.28 cm/sec were found to initially contract upon the injection of gas. In contrast, beds of particles having minimum fluidizing velocities exceeding tins value were found to expand. On a mesure, sur line graiide echelle de vitesses de liqnides et de gaz, les retentions dans chaque phase dans le cas de lits fluididses B deux phases (liquide et air) et B trois phases (liquide, air et solides). On a fait les expkrimces dans un lit considkrable B deux dimensions. On a employ6 trois solides doiit la grosseur des particules variait entre 1 et 6 millimktres. On a dkerminC l'effet de la viscositk (1 a 70 centipoises) au nioyen de sucre et de cellulose carboxymkhylCe de diffkreiitcs concentrations. On a utilisk divers niClanges d'acktone et d'eaii pour examiner I'effet de la tension superficielle pour une kchelle de 40 A 73 dynes par centimktre. On a constate que, lorsqu'on injectait du gaz, il y avait unc contraction initiale des lits formks de particules dont la vitessc fluidisante niiiiimale dam le liquide Ctait infkrieure B 1.28 centimktres A la seconde, tandis qn'il y avait expansion desdits lits lorsque la vitesse en question exckdait 1.28 centimhtres h la seconde.