Flow structure of the solids in a 3‐D gas–liquid–solid fluidized bed

Larachi, Faı̈çal; Cassanello, Miryan; Chaouki, Jamal; Guy, Christophe

doi:10.1002/aic.690420905

Cited by 53 publications

(29 citation statements)

References 26 publications

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“…Within the range of U g spanned in this study and for all the beds used, the time-averaged radial motion in the FDR exhibits the expected feature of zero velocity. Advectionless radial flow was also reported by other investigators on the liquid or solids behavior in: bubble columns [10±13], gas- [11,14] and three-phase [3,15] fluidized beds.…”

Section: Mean Velocitysupporting

confidence: 52%

“…3d) occurs closer to the center (r/R » 0.35). The radial turbulent velocities are minimal near the vessel walls, whereas they are the highest within the fast bubble central flow region where the bubblelike swinging and spiral/rocking movements of the particles were detected [3]. Axial turbulent velocities are systematically larger than their radial counterparts, hence the turbulent kinetic energy which is responsible for local mixing is mainly contained in the axial turbulent velocity u¢ z .…”

Section: Turbulent Velocitymentioning

confidence: 98%

“…Fig. 2 shows the ± 20% envelopes (dotted lines) and the averaged profiles (solid lines) for run D 3 . The narrow scatters confirm that it is reasonable to identify such an FDR where 1-D representation is possible for the column size used in our study.…”

Section: Particle Tracking Systemmentioning

confidence: 98%

“…The resulting dynamic solids flow is regarded as a core-annulus-annulus structure: a central fast bubble flow core in which the solids swirl upward in a bubblelike motion, a vortical annulus where particles are entrapped in evanescent vortices, and a relatively bubble-free wall annulus in which the solids spiral down [1,3]. The turbulent behavior of the solids was assessed by Del Pozo et al [6] who devised a new technique which allowed for the detection of particle-particle collisions in gas-liquid-solid fluidized beds from perturbation in the diffusion current of tethered electrodes.…”

Section: Introductionmentioning

confidence: 99%

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Mean and Turbulent Particle Velocity in the Fully Developed Region of a Three-Phase Fluidized Bed

Kiared

Larachi²,

Chaouki

et al. 1999

Chem. Eng. Technol.

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A thorough experimental description of the time-averaged solids flow in the fully developed region of a cylindrical gas-liquidsolid fluidized bed was provided by using a noninvasive radioactive particle tracking technique (RPT). The 3-D local instantaneous velocity components (radial, axial, azimuthal) of a single radioactive solid tracer, having properties identical to those of the solids in the bed, were measured noninvasively over extended time periods to establish the radial distributions in the fully developed region of axial and radial particle mean and turbulent velocities, shear stress, and axial and radial eddy diffusion coefficients. Glass beads and polyvinyl chloride particles of various shapes and sizes were water-fluidized singly or as binary mixtures in a 100 mm ID Plexiglas column over air and water superficial velocity ranges that spanned the dispersed bubble, coalesced bubble, and transitional flow regimes.

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Section: Mean Velocitysupporting

confidence: 52%

Section: Turbulent Velocitymentioning

confidence: 98%

Section: Particle Tracking Systemmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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Mean and Turbulent Particle Velocity in the Fully Developed Region of a Three-Phase Fluidized Bed

Kiared

Larachi²,

Chaouki

et al. 1999

Chem. Eng. Technol.

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“…In principle, this technique can also be applied to other multiphase reactors such as gas fluidized or liquid-fluidized beds and threephase fluidized beds. Larachi et al (1996) applied their radioactive particle tracking (RPT) technique to determine the time-averaged solids velocity in a threephase fluidized bed.…”

Section: Radio-active Particle Trackin 9 Methodsmentioning

confidence: 99%

Computational fluid dynamics applied to gas-liquid contactors

Delnoij

Kuipers

Swaaij

1997

Chemical Engineering Science

148

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Abstract-In this paper a "hierarchy of models' is discussed to study the fluid dynamic behaviour of gas-liquid bubble columns. This 'hierarchy of models' consists of a Eulerian Eulerian two fluid model, a Eulerian-Lagrangian discrete bubble model and a Volume Tracking or Marker Particle model. These models will be briefly reviewed and their advantages and disadvantages will be highlighted. In addition, a mixed Eulerian Lagrangian model and a volume tracking model, both developed at Twente University, will be discussed. Some selected results obtained with these models will be presented with emphasis on the results obtained with the volume tracking model. Finally, a brief discussion on advanced experimental techniques, which reflect the recent progress in experimental fluid dynamics, will be presented. ~ 1997

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Dynamics of fines deposition in an alternating semifluidized bed

et al. 2008

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in Wiley InterScience (www.interscience.wiley.com).A semifluidized bed was proposed to allay bed plugging during the filtration of fines-hydrocarbon suspensions. Mitigation of plugging was allowed by alternating semifluidization during capture with unconstrained fluidization for removal of deposits. Solids holdup conditions were established to prevent deposition in the fluidization section. The cyclic parameters were varied to allow efficient removal of deposits during washing. Analysis with a filtration model accounting for solids detachment in the fixed bed section revealed that the fluidization section favored growth of aggregate size entering the fixed bed. Analysis of the split ratios between fixed and fluidized bed heights revealed that the shallowest fluidization sections delayed deposition in the fixed bed. In cyclic operation, reversibility of the semifluidized bed was best recovered via gas injection during the washing stages. However, the filtration times in successive cycles shortened with increasing washing times but lengthened with increasing the washing superficial suspension velocity.Dotted lines/empty symbols shows simulations by depth filtration model Eqs. 7-14. Figure 8. Effect of split ratio on overall capture efficiency and global filter coefficient vs. specific deposit (R 5 1; H F 5 0.25 m), (R 5 2; H F 5 0.34 m), (R 5 3; H F 5 0.34 m), (R 5 '; H F 5 0.42 m), U Lsf 5 0.042 m/s.

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Flow structure of the solids in a 3‐D gas–liquid–solid fluidized bed

Abstract: Local and macroscopic solids flow structure and kinematics in a 3-0 gas -liquid -solid fluidized bed were studied using a noninvasive radioactive-particle tracking (RPT)

Cited by 53 publications

References 26 publications

Mean and Turbulent Particle Velocity in the Fully Developed Region of a Three-Phase Fluidized Bed

Mean and Turbulent Particle Velocity in the Fully Developed Region of a Three-Phase Fluidized Bed

Computational fluid dynamics applied to gas-liquid contactors

Dynamics of fines deposition in an alternating semifluidized bed

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