Incipient fluidization condition for a tapered fluidized bed

Yan, Shi; Yu, Yang; Fan, L.T.

doi:10.1021/i100016a018

Cited by 55 publications

(35 citation statements)

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“…A velocity gradient exists in the axial direction in tapered bed leading to unique dynamic characteristics of the bed. Due to this characteristic, tapered fluidized beds have found wide application in many industrial processes such as, waste water treatment [1] immobilized biofilm reaction, incineration of waste materials, coating of nuclear fuel particles, crystallization, coal gasification, roasting sulfide ores [2] and food processing [3], etc.…”

Section: Introductionmentioning

confidence: 99%

“…with less pressure fluctuations [1]. Tapered fluidized beds are very useful for fluidization of materials with a wide particle size distribution, as well as for exothermic reactions [4] and also for extensive particle mixing [5].…”

Section: Introductionmentioning

confidence: 99%

“…Some investigations have been carried out in tapered fluidized bed dynamics during last two decades [1][2][3][4]. Schaafsma et al [5] studied particle flow pattern and segregation phenomena in tapered fluidized bed granulator using segregation experiment and positron emission particle tracking experiments (PEPT) and concluded that the flow and segregation phenomena is totally different from conventional (cylindrical) beds.…”

Section: Introductionmentioning

confidence: 99%

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Computational fluid dynamics and experimental study of the hydrodynamics of a gas–solid tapered fluidized bed

Biswal

2011

Applied Mathematical Modelling

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a b s t r a c tIn the present work, experimental and numerical studies for the hydrodynamics in a gassolid tapered fluidized bed have been carried out. The experimental results obtained by carrying out experiments in a tapered fluidized bed for glass bead (spherical) of 2.0 mm and dolomite (non-spherical particles) of 2.215 mm in diameter, were compared with the computational fluid dynamics (CFD) simulation results, using a commercial CFD software package, Fluent. The gas-solid flow was simulated using the Eulerian-Eulerian model and applying the kinetic theory of granular flow for solid particles. The Gidaspow drag model was used to calculate the gas-solid momentum exchange coefficients. Pressure drops predicted by the CFD simulations agreed reasonably well with experimental measurements for both types (spherical and non-spherical) of particles. Good agreement was also obtained between experimental and CFD predicted bed expansion ratios for both types of particles. Present study provides a useful basis for further works on the CFD of tapered fluidized bed.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Computational fluid dynamics and experimental study of the hydrodynamics of a gas–solid tapered fluidized bed

Biswal

2011

Applied Mathematical Modelling

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“…But some of these results are limited to regular particles only. Some of the previous investigations include fixed bed pressure drop calculations [7], flow regimes, incipient condition of fluidization, voidage distribution and bed expansion calculations [8] and development of a model for maximum pressure drop at incipient fluidization condition of a tapered fluidized bed [9]. The model developed by Shi et al [9] is based on Ergun's equation and neglects friction between the particles and the wall.…”

Section: Introductionmentioning

confidence: 99%

Minimum fluidization velocities and maximum bed pressure drops for gas–solid tapered fluidized beds

Mohanty

Biswal

2007

Chemical Engineering Journal

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“…There have been many studies on hydrodynamic characteristics of liquid-solid fluidization in tapered beds (Kolar, 1963;Koloini and Farkas, 1973;Murthy et al, 1981;Maruyama et al, 1984;Shi et al, 1984;Webster and Perona, 1988;Peng and Fan, 1997). But similar investigations are limited in gas-solid fluidized beds.…”

Section: Introductionmentioning

confidence: 99%

Hydrodynamics of gas–solid fluidization in tapered beds

et al. 2009

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Gas-solid fluidization has a wide range of industrial applications like catalytic reactions, combustion, gasification, etc. In a number of these applications, there is particle size reduction during the operation leading to severe entrainment and limitation of operating velocity. The various problems associated with particles of different sizes or changing particles sizes could be overcome by adopting tapered beds in fluidization operation.In the present investigation, the fluidization phenomenon in tapered beds has been critically assessed through experimental investigations using particles of different sizes and materials and wide range of apex angles of the vessels. The effect of particle size and apex angle on the fluidization behaviour is clearly brought out which has not been reported so far in literature. The importance of compressive force existing in tapered beds is highlighted.In addition, correlations for all hydrodynamic characteristics, viz. critical fluidization velocity, minimum velocity for full fluidization, maximum velocity for defluidization, peak pressure drop, fluctuation ratio, compressive force, and hysteresis have been developed some of which are proposed for the first time.La fluidisation gaz-solide revêt un vasteéventail d'applications industrielles comme les réactions catalytiques, la combustion, la gazéification, etc. Pour un certain nombre deces applications, il y a une réduction granulométrique durant l'activité menantà un entraînement età une limitation intenses de la vitesse de fonctionnement. Les divers problèmes liés aux particules de dimensions différentes ou aux dimensions de particules changeantes pourraientêtre surmontésen adoptant les lits coniques dans les activités de fluidisation. Dans le cadre de la présenté etude, lephénomène de fluidisation dans les lits coniques aétéévalué de façon critique au moyen devérifications expérimentales employant des particules de dimensions et de matières différentes et d'un vasteéventail d'angles de sommet de fluidiseurs. L'effet de la dimension des particules et del'angle des sommets sur le comportement de la fluidisation est nettement mis enévidence, ce quin'a pasété soulevéà venir jusqu'ici dans la documentation. L'importance de la force decompression qui existe dans les lits coniques est mise enévidence. De plus, les corrélations relativement a l'ensemble des caractéristiques hydrodynamiques, c.-à-d. la vitesse de fluidisation critique, la vitesse minimale de fluidisation complète, la vitesse maximale de défluidisation, la chute des pics de pression, le taux de fluctuation, la force de compression et l'hystérésis, ontétéélaborées, certaines d'entre ellesétant avancées pour la première fois.

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Incipient fluidization condition for a tapered fluidized bed

Cited by 55 publications

References 2 publications

Computational fluid dynamics and experimental study of the hydrodynamics of a gas–solid tapered fluidized bed

Computational fluid dynamics and experimental study of the hydrodynamics of a gas–solid tapered fluidized bed

Minimum fluidization velocities and maximum bed pressure drops for gas–solid tapered fluidized beds

Hydrodynamics of gas–solid fluidization in tapered beds

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