Numerical investigation of gas‐driven flow in 2‐D bubble columns

Pan, Y.; Duduković, Milorad P.; Chang, Ming

doi:10.1002/aic.690460303

Cited by 111 publications

(60 citation statements)

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“…In the past we have shown qualitative comparisons with 2D experiments using 2D codes (Kumar et al, 1994b(Kumar et al, , 1995b as well as fully quantitative comparison (Pan, Dudukovic and Chang, 2000). In our computations we utilize the standard formulation for the drag, and base the drag coefficient on the assumed uniform bubble diameter.…”

Section: Comparison Of Carpt-ct Data and Cfd Predictionsmentioning

confidence: 99%

Opaque Multiphase Reactors: Experimentation, Modeling and Troubleshooting

Duduković¹

2000

Oil & Gas Science and Technology - Rev. IFP

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Résumé -Réacteurs polyphasiques opaques : expérimentation, modélisation et traitement des incidents -Les réacteurs polyphasiques sont largement utilisés dans les industries pétrolière, chimique, pétrochimique, pharmaceutique et métallurgique, aussi bien pour la transformation des matières que pour la réduction de la pollution. La plupart des réacteurs présentant un intérêt industriel (colonnes à bulles avec solides en suspension -à slurry -, lits entraînés -risers -gaz-solide et lits fluidisés, lits bouillonnants et cuves agitées) sont opaques, parce que la phase dispersée occupe une fraction de volume importante. Tous les phénomènes physiques jouant sur la dynamique des fluides de tels systèmes ne sont pas encore entièrement compris. Cela rend extrêmement difficile la prédiction de paramètres importants du procédé, tels que la perte de charge, les profils de vitesse et de rétention, le taux de rétromélange, etc. Les concepts industriels reposent sur des corrélations, et celles-ci sont sujettes à une grande incertitude dès que l'on s'écarte des conditions d'exploitation des bases de données. Dans la plupart des cas, il serait bienvenu de prévoir les paramètres du procédé en se basant sur des modèles de dynamique des fluides. Cependant, même les meilleurs modèles (ceux qui sont aptes à traiter des récipients et des conduites de grand volume) nécessitent des lois de fermeture pour les termes d'interaction des phases, qui sont encore actuellement incertains et sujets à discussion. Il est donc nécessaire de vérifier ces modèles en mesurant avec précision les grandeurs que l'on souhaite prédire à l'aide de ces modèles, c'est-à-dire les taux et les profils de rétention des différentes phases, les profils de vitesse, le rétromélange, etc. Mais ces systèmes sont opaques, et il est donc impossible de « voir » à l'intérieur, ce qui apparaît comme un cercle vicieux et laisse présager que les prédictions des modèles sont destinées à rester invérifiées. Heureusement, comme deux importantes et récentes études l'ont montré (Chaouki et al., 1997a(Chaouki et al., , 1997b, des techniques peuvent nous offrir les informations souhaitées. Nous examinons ici deux d'entre elles : la tomographie assistée par rayon gamma (CT) pour la mesure des profils de rétention, et le traçage des particules radioactives assisté par ordinateur (CARPT) pour la mesure des profils de vitesse et des paramètres de rétromélange. Nous montrons comment utiliser ces techniques pour obtenir une information sur les systèmes industriellement intéressants et comportant des catalyseurs en mouvement comme les réacteurs élévateurs (risers) gaz-solide ou gaz-liquide, et les colonnes à bulles gaz-liquide. L'aptitude des codes CFD (Computational Fluid Dynamics) existants à prédire correctement les grandeurs hydrodynamiques observées est également brièvement discutée. Nous abordons ensuite les problèmes de l'écoulement disphasique dans les lits garnis, de l'évolution des techniques expérimentales et des modèles utilisés pour mieux quantifier les paramètres de ces réacte...

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Section: Comparison Of Carpt-ct Data and Cfd Predictionsmentioning

confidence: 99%

Opaque Multiphase Reactors: Experimentation, Modeling and Troubleshooting

Duduković¹

2000

Oil & Gas Science and Technology - Rev. IFP

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“…The gas phase is treated as a particulate phase, as is the standard practice in the CFD simulation of gas-liquid bubble columns (e.g. Pan, et al 2000 ). Since the flow inside the column is not far from homogeneous, one can add the three momentum equations and see that the total pressure is the sum of the individual phase pressures and that the mixture viscosity is the sum of the three phase viscosities.…”

Section: Introductionmentioning

confidence: 99%

Computational and Experimental Modeling of Slurry Bubble Column Reactors

Lam¹,

Gamwo²,

Gidaspow³

2002

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The objective of this study was to develop a predictive experimentally verified computational fluid dynamics (CFD) model for gas-liquid-solid flow. A three dimensional transient computer code for the coupled Navier-Stokes equations for each phase was developed and is appended in this report. The principal input into the model is the viscosity of the particulate phase which was determined from a measurement of the random kinetic energy of the 800 micron glass beads and a Brookfield viscometer. The details are presented in the attached paper titled "CFD Simulation of Flow and Turbulence in a Slurry Bubble Column". This phase of the work is in press in a refereed journal (AIChE Journal, 2002) and was presented at the Fourth International Conference on Multiphase Flow (ICMF 2001) in New Orleans, May 27-June 1, 2001 (Paper No. 909).The computed time averaged particle velocities and concentrations agree with Particle Image Velocimetry (PIV) measurements of velocities and concentrations, obtained using a combination of gamma-ray and X-ray densitometers, in a slurry bubble column, operated in the bubbly-coalesced fluidization regime with continuos flow of water. Both the experiment and the simulation show a down-flow of particles in the center of the column and up-flow near the walls and nearly uniform particle concentration.Normal and shear Reynolds stresses were constructed from the computed instantaneous particle velocities. The PIV measurement and the simulation produced instantaneous particle velocities. The PIV measurement and the simulation produced similar nearly flat horizontal profiles of turbulent kinetic energy of particles. To better understand turbulence we studied fluidization in a liquid-solid bed. This work was also presented at the Fourth International Conference on Multiphase Flow (ICMF 2001, Paper No. 910).To understand turbulence in risers, measurements were done in the IIT riser with 530 micron glass beads using a PIV technique. This report summarizes the measurements and simulations completed so far. This work will continue under the sponsorship of the National Science Foundation and Dow Corning Corporation. This phase of the work is part of the DOE/Industry/University Multiphase Fluid Dynamics Research Consortium.Optimization of the LaPorte pilot plant reactor was attempted by rearranging the heat exchangers. The paper accepted for presentation at the Sixth World Congress of Chemical Engineering, Melbourne, Australia, September 23-27, 2001 is a part of this report.ii Disclaimer This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency therefor, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, pro...

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“…Sokolichin and Eigenberger [3], Pan et al [4], and Monahan et al [5] • ere e u . "d h lvin its eq uati n of m ti on th_ rough the _ hqUJ p ase.…”

Section: Introductionmentioning

confidence: 99%

“…Numerical simulations of bubble columns either employing Eulerian-Eulerian models [ [1][2][3][4][5], Euleri an-Lagrang ian mode ls [6][7][8] , or Volume of Fluid (VOF) [9] methods were surveyed. The Eulerian-Eulerian model treats di spersed (gas bubb les) and continuous (liquid) phases as interpenetrating continua, and describes the motion for gas and liquid phases Ill an Eulenan frame of reference.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulations of Gas-Liquid Flow Dynamics in Bubble Columns

2006

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There is great potential for using computational fluid dynamics (CFD) as a tool in scale-up and design of bubble columns. Full-scale experimentation in bubble columns is expensive and CFD is an alternative approach to study bubble column hydrodynamics. However, CFD can be computationally intensive as a predictive tool for a full three-dimensional geometry. In this paper, a 0.2 m diameter semi-batch bubble column is numerically simulated and the results are compared to experimental measurements performed by Rampure et al. [1]. The objectives are to examine and determine an appropriate set of numerical parameters and to determine if two-dimensional simulations are able to accurately predict observed bubble phenomena so that the computational cost can be reduced. A two-fluid Eulerian-Eulerian model is employed to represent each phase as interpenetrating continua and the conservation equations for mass and momentum for each phase are ensemble-averaged. Time-averaged gas holdup is mainly examined due to its significant role in gasliquid mass transfer and to compare to available data. Numerical predictions are presented for gas holdup at various axial heights as a function of radial position for a superficial gas velocity of 0.1 m/s. The numerical predictions exhibit the axial development of the gas holdup profile phenomena; that is, the gas holdup at the center of the column increases with increasing axial height. The effects of grid resolution and convergence criteria on the numerical predictions are also demonstrated. However, FD ca n be computationally inten ive a a predict ive too l fo r a full th reedimensional geo metry. In th i paper, a 0.2 m diameter semibatch bubble column is numerica ll y imul ated and the res ults are compared to ex perimental meas urements performed by R ampure et al. [ !] . The objecti ve are to exa mine and determine an appropriate set of numerica l parameters and to determine if two-dimensional simul ations are abl e to accuratel y predtct observed bubble phenomena so that the computational cost can be reduced. A two-fluid Euleri an-Eul eri an model is employed to represent each phase as interpenetrating continua and the conservation equations fo r mass and momentum for each phase are ensemble-averaged. Time-averaged gas holdup ts mamly examined due to its significant role in gas-liquid mass transfer and to compare to available data. Numerical predictions are presented for gas holdup at various ax ial heights as a function of radial position for a superfi cial gas velocity of ~· 1 mls. The numerical predictions exhibit the axial evelopment of the gas holdup profile phenomena · that is the gas h ld ' '. 0 up at the center of the column increases with Increasing axial height. The effects of grid resolution and convergence .t . d en ena on the numerical predictions are also emonstrated.

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Numerical investigation of gas‐driven flow in 2‐D bubble columns

Abstract: Gas-liquid bubbly flow in 2-D bubble columns was studied by numerical simulation. A Eulerian-Eulerian two-fluid model

Cited by 111 publications

References 30 publications

Opaque Multiphase Reactors: Experimentation, Modeling and Troubleshooting

Opaque Multiphase Reactors: Experimentation, Modeling and Troubleshooting

Computational and Experimental Modeling of Slurry Bubble Column Reactors

Numerical Simulations of Gas-Liquid Flow Dynamics in Bubble Columns

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