Behaviour of gas-fluidized beds of fine powders part I. Homogeneous expansion

Abrahamsen, A.R.; Geldart, D.

doi:10.1016/0032-5910(80)85005-4

Cited by 256 publications

(158 citation statements)

References 7 publications

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“…Although non-spherical particles have lower U mf , much higher U mb is predicted compared with spherical particles for both particle sizes considered. The predicted results of spherical particles agree well with the correlation of Abrahamsen and Geldart [11].…”

Section: Fluidization Parameterssupporting

confidence: 84%

Discrete element modeling of gas fluidization of fine ellipsoidal particles

Gan

Zhou

Zou

et al. 2013

AIP Conference Proceedings

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Abstract. Particle properties are important factors affecting gas fluidization. In the present work, the effects of particle size and shape on the fluidization characteristics are studied using the combined approach of computational fluid dynamics for gas phase and discrete element method for particles. It shows that a bed becomes loosely packed when particle size becomes small. The minimum fluidization velocity increases exponentially with the increase of particle size. Higher minimum bubbling velocities are predicted for ellipsoidal particles compared with spherical ones. "Chain phenomenon" exists in the expanded and fluidized beds for fine prolate particles.

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Section: Fluidization Parameterssupporting

confidence: 84%

Discrete element modeling of gas fluidization of fine ellipsoidal particles

Gan

Zhou

Zou

et al. 2013

AIP Conference Proceedings

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“…Thus, the lower the pressure, the shorter the defluidization length. Computations suggest that defluidization length strongly increases with the change in U mb /U mf , as expected [20]. Defluidization length as a function of catalyst mass flux for various gas densities.…”

Section: Figure 26supporting

confidence: 76%

Fcc: Fluidization Phenomena and Technologies

Gauthier

Bayle

Leroy

2000

Oil & Gas Science and Technology - Rev. IFP

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Résumé -FCC : phénomènes de fluidisation et technologies -Le procédé de craquage catalytique (FCC) est utilisé dans la majorité des raffineries pour convertir les charges lourdes. Depuis plus de 50 ans, les développements du catalyseur et l'amélioration de la technologie de la zone réactionnelle ont permis une évolution continue de ce procédé, évolution qui n'est sans doute pas terminée, permettant notamment de traiter des charges de plus en plus lourdes. Dans cet article, les moyens nécessaires au développement de technologies adaptées au procédé de craquage catalytique sont discutés à travers les exemples de développement d'un séparateur rapide en tête de riser et d'un échangeur de chaleur permettant de refroidir le catalyseur pendant la régénération. Les aspects liés à l'écoulement de catalyseur fluidisé à travers la zone réactionnelle sont également abordés. NOTATIONS Main SymbolsA cross sectional area, m 2 C concentration, mol/m 3 D diameter, m F mass flow rate, kg/s H height, m k pressure drop constant K pressure drop constant M ratio of the particle mass flow rate over gas mass flow rate N number of CSTRs P pressure, Pa PB pressure balance, Pa R radius, m Q volumetric flow rate, m 3 /s U velocity, m/s V superficial velocity, m/s W mass flux, kg/s/m 2 X axial position, m ε holdup of a given phase τ time constant, s ρ density, kg/m 3 Subscripts b related to fluidized bed conditions br bubble velocity relative to suspension c related to cyclone d related to dipleg conditions dn related to dipleg conditions for negative pressure separators dp related to dipleg conditions for positive pressure separators G related to gas flowing to the separator gas exit g related to gas I related to inlet conditions i related to intersticial gas mf related to minimum fluidization conditions mb related to minimum bubbling fluidization conditions p related to particle s related to gas flowing to the separator dipleg sg related to gas for superficial velocity sl related to slip between gas and particles sk related to skeletal t related to tracer tc related to tapped conditions in defluidized conditions.

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“…Several investigators (Subzwari et al, 1978;Abrahamsen and Geldart, 1980; Guedes de Carvalho, 1981) have found that fluidization at higher gas pressures can have a favourable effect on fluidization behaviour, as demonstrated by increased bed height and smaller gas bubbles. This is remarkable as the particle size and the particle density are constant.…”

Section: Forcesmentioning

confidence: 99%