Liquid dispersion in gas—liquid fluidized beds

El‐Temtamy, Seham A.; El-Sharnoubi, Yousef O.; El-Halwagi, Mohammed M.

doi:10.1016/0300-9467(79)80025-8

Cited by 33 publications

(12 citation statements)

References 13 publications

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“…The dispersion data were interpreted by means of the axially dispersed plug flow model (Bischoff and Levenspiel, 1963). This model has been found to adequately describe axial mixing in liquid-solid (Kim et al, 1972), gas-liquid (Eissa and Schugerl, 1975;Oki and Inoue, 1970) and three phase fluidized beds (El-Temtamy et al, 1979;Kim et al, 1972;Michelsen and Ostergaard, 1970;Kim and Kim, 1983;Kang and Kim, 1986).…”

Section: Measurements Of Phase Holdups and Axial Dispersion Coeficientsmentioning

confidence: 96%

Axial dispersion characteristics of three (liquid‐liquid‐solid) phase fluidized beds

1989

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The effects of the continuous and dispersed phase velocity and particle size on the axial dispersion of the continuous phase have been determined in two (liquid-liquid) and three (liquid-liquid-solid) phase fluidized beds. In a cocurrent liquid-liquid flow system, the axial dispersion coefficient increases with both the dispersed and continuous phase velocities. In three phase fluidized beds, the coefficient increases with dispersed phase velocity but it decreases with the particle size. Also the coefficient exhibits a maximum value with an increase in the continuous phase velocity at the lower dispersed phase velocities, but it increases with the continuous phase velocity at higher dispersed phase velocities. The axial dispersion coefficients in terms of Peclet number have been correlated in terms of the ratio of fluid velocities and the ratio of the particle size to column diameter, based on the isotropic turbulence theory.Les effets de la vitesse des phases dispersCe et continue et de la taille des particules sur la dispersion axiale de la phase continue, sont dktermines dans des lits fluidises diphasiques (liquide-liquide) et triphasiques (liquide-liquidesolides). Dans un s y s t h e d'ecoulement liquide-liquide 2 cocourant, le coefficient de dispersion axiale augmente avec les vitesses des deux phases dispersee et continue. Dans les lits fluidises triphasiques, le coefficient augmente avec la vitesse de phase dispersee mais diminue avec la taille des particules. De mCme, le coefficient montre une valeur maximale avec une augmentation de la vitesse de phase continue aux vitesses de phase disperskes les plus basses, mais celui-ci augmente avec la vitesse de phase continue ii des vitesses de phase dispersCe plus ClevCes. Les coefficients de dispersion axiale en terrnes du nombre de Peclet ont Ct C corrClCs a partir des vitesses de fluide et du rapport entre la taille des particules et le diamktre de la colonne en utilisant la thCorie de turbulence isotrope.Keywords: cocurrent liquid-liquid upflow, liquid-liquid-solid fluidization, axial dispersion.iquid-liquid-solid three-phase fluidized bed operation can 216

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Section: Measurements Of Phase Holdups and Axial Dispersion Coeficientsmentioning

confidence: 96%

Axial dispersion characteristics of three (liquid‐liquid‐solid) phase fluidized beds

1989

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“…Also shown in Figure 5(a) are the data of radial Peclet number, Pe,,, obtained solely for radial liquid mixing in a three-phase fluidized bed by El-Temtamy et al (1979). I mm glass beads vigorous bed mixing occurs in the coalesced bubble flow and a considerable reduction of Pe,,, with gas velocity results.…”

Section: Radial Peclet Number For Heat Transfermentioning

confidence: 99%

“…With increasing gas velocity, however, the flow regime shifts from the dispersed bubble flow to the slugging regime via the transitional regime, and a significant decrease of Per,, occurs because of the violent stirring by slug bubbles. Also shown in Figure 5(a) are the data of radial Peclet number, Pe,,, obtained solely for radial liquid mixing in a three-phase fluidized bed by El-Temtamy et al (1979). The Reynolds number for the data of El-Temtamy et al is multiplied by pJp313K, where p313K is the water viscosity at 313 K, equivalent to the average temperature of the present work, to adjust the Reynolds number range of the data on Pe,) by El-Temtamy et al to that of the present data on Pe,,,.…”

Section: Radial Peclet Number For Heat Transfermentioning

confidence: 99%

Wall‐to‐bed heat transfer in liquid—solid and gas—liquid—solid fluidized beds part II: Gas—liquid—solid fluidized beds

1986

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Wall-to-bed heat transfer in gas-liquid-solid fluidized beds with a cocurrent upflow was analyzed on the basis of a series thermal resistance model. The effective radial thermal conductivity and the apparent wall heat transfer coefficient were determined over a wide range of experimental conditions. The behavior of the effective thermal conductivity strongly depends on the flow mode for the three-phase fluidized bed, directly indicating the trend of the radial liquid mixing. The modified Peclet number for the radial thermal diffusivity takes on a minimum with respect to the liquid velocity in a manner similar to that in a liquid-solid fluidized bed, but the value of the modified Peclet number decreases significantly with gas velocity. The apparent wall heat transfer coefficient can be correlated well with a Colburn type equation which at zero gas velocity reduces to the same equation as that proposed for liquid-solid fluidization, as follows:Le transfert de chaleur lit-paroi dans les lits fluidises gaz-liquide-solides avec un Ccoulement ascendant cocourant a CtC analysk a I'aide d'un modkle de resistances thermiques en sCrie. La conductivitk thermique radiale effective et le coefficient de transfert de chaleur apparent a la paroi ont CtC dCterminCs pour des conditions exp5rimentales trks variCes.Le comportement de la conductivitk thermique effective dtpend fortement du mode d'tcoulement dans le lit fluidist trois phases, ce qui indique directement la tendance du mklangeage radial du liquide. Le nombre de Peclet modifiC pour la diffusivitt thermique radiale atteint un minimum avec une augmentation de la vitesse du liquide de la m&me manikre que dans un lit fluidisk solides-liquide, mais la valeur du nombre de Peclet modifiC diminue de manikre significative avec la vitesse des gaz. Le coefficient de transfert de chaleur apparent ti la paroi peut &tre corrClC a I'aide d'une Cquation de type Colburn qui, lorsque la vitesse des gaz est nulle, devient identique a celle proposCe pour la fluidisation solides-liquide, a savoir: j b = 0,137 Re;,,-"."' hree-phase fluidized beds with cocurrent upflow of gas

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“…El-Temtamyet al [9] geben fur ihreeigenen MeBergebnisse in Gas/Flussigkeits-fluidisierten Wirbelbetten sowie fur MeBwerte von Michelsen und Ostergaard [lo] eine Korrelation an, die den Effekt des Reaktordurchmessers richtig erfaBt, aber wegen der Nichtberucksichtigung des Einflusses der Gasgeschwindigkeit auf DL insgesamt unbefriedigend ist. Eine einheitliche Korrelation fur die Dispersion der kontinuierlichen Phase in Mehrphasen-Reaktoren wurde von Joshi …”

Section: Dispersionunclassified

Transporterscheinungen in Dreiphasen‐Reaktoren mit fluidisiertem Feststoff

Deckwer

Schumpe

1983

Chemie Ingenieur Technik

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Wolf-Dieter Deckwer und Adrian Schumpe"Dreiphasen-Reaktoren mit fluidisiertem Feststoff weisen einen breiten Einsatzbereich auf. Er reicht von katalytischen Hydrierungen, Oxidationen, Polymerisationen und Synthesegas-Umsetzungen bis hin zu Kohleverfliissigungs-Anlagen und Anwendungen in der Biotechnologie. Wesentliche Vorteile dieser Reaktoren stellen die intensive Beruhrung der Phasen und ihre im Vergleich zu anderen Reaktortypen hohe thermische Stabilitiit dar. In diesem Beitrag werden die fluiddynamischen Modellvorstellungen qualitativ behandelt und dann der Erkenntnisstand iiber die Transporterscheinungen innerhalb und zwischen den Phasen referiert. Zum AbschluB wird auf die Modellbildung dieser Reaktoren eingegangen.Transport phenomena in three-phase reactors with fluidized solids. Three-phase reactors with fluidized solids have a wide range of application. It extends from catalytic hydrogenation, oxidations, polymerizations, and reactions of synthesis gas to coal liquefaction plant and applications in biotechnology .Considerable advantages of these reactors lie in the intense degree ofcontact between the phases and in their high thermal stability relative to other types of reactors. Pertinent model concepts of fluid dynamics are treated qualitatively, and our present knowledge about transport phenomena within and between the phases is reviewed. Modelling ofthese reactors is considered in conclusion. * prof. Dr, w . -~, Deckwev und Dr, A , phurnpe, Fachbereich Der Einsatzbereich von Reaktoren mit fluidisiertem Feststoff Chemie -Fachrichtung Technische Chemie, Universitat Olden-ist breit. In der Mehrzahl aller Falle stellt der Feststoff einen burg, Postfach 2503, 2900 Oldenburg. Katalysator dar, dessen Partikeldurchmesser von einigen pm 591

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Liquid dispersion in gas—liquid fluidized beds

Cited by 33 publications

References 13 publications

Axial dispersion characteristics of three (liquid‐liquid‐solid) phase fluidized beds

Axial dispersion characteristics of three (liquid‐liquid‐solid) phase fluidized beds

Wall‐to‐bed heat transfer in liquid—solid and gas—liquid—solid fluidized beds part II: Gas—liquid—solid fluidized beds

Transporterscheinungen in Dreiphasen‐Reaktoren mit fluidisiertem Feststoff

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