The onset of slugging in gas—solid fluidized beds with large particles

Ho, Tho-Ching; Yutani, N.; Fan, L.T.; Walawender, Walter P.

doi:10.1016/0032-5910(83)87015-6

Cited by 25 publications

(13 citation statements)

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“…The onset of the slug regime is characterized by the minimum superficial gas velocity for which the frequency of the pressure fluctuation obtains a constant value. In contrast to the minimum fluidization and minimum bubbling velocities, the literature presents much less experimental data on the minimum slugging velocity [16,19,20,32,33]. Moreover, according to several studies, the minimum slugging velocity depends on the bed height and column diameter.…”

Section: Minimum Slugging Velocitymentioning

confidence: 95%

“…The experiments referred to four different research groups used eight different materials, with particle size ranges of 0.058-5.2 mm, column diameter ranges of 0.025-0.308 m, particle density ranges of 1125-2680 kg/m 3 and void fraction ranges of 0.46-0.73. The minimum slugging velocity measurements presented by Baeyens and Geldart [19] and Ho et al [32] were done by using the pressure fluctuation method. Broadhurst and Becker [20] determined the onset of slugging by visual observations.…”

Section: Minimum Slugging Velocitymentioning

confidence: 99%

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Flow regime diagram for vertical pneumatic conveying and fluidized bed systems

Rabinovich

Kalman

2011

Powder Technology

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Section: Minimum Slugging Velocitymentioning

confidence: 95%

Section: Minimum Slugging Velocitymentioning

confidence: 99%

Flow regime diagram for vertical pneumatic conveying and fluidized bed systems

Rabinovich

Kalman

2011

Powder Technology

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“…An earlier study carried out by Ho (1983) stated that although the experimental results have indicated that the effect the bed size on the onset of slugging appeared to be insignificant for the relatively large particles.…”

Section: Effect Of Particle Shapementioning

confidence: 80%

“…There has been no work exclusively on the particle scale presented in this study. It will be shown that the relatively straight forward procedure of analyzing pressure fluctuations in a fluidized bed is an effective method for determining when the bed enters the slugging regime.Fluidization, in a gas-solid bed, begins when the weight of the particles is balanced by the buoyancy and drag caused by the flow of gas through the bed (Ho, 1983). If the superficial gas velocity is raised above the minimum fluidization velocity, aggregative fluidization is achieved which is characterized by two distinct phases that can be observed within the bed.…”

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confidence: 99%

Slugging characteristics of group d particles in fluidized beds

Dimattia¹,

Amyotte

Hamdullahpur

1997

Can J Chem Eng

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Pressure fluctuations within a bed of Type D particles (coarse sand, long grain rice, red spring wheat, 10 mm glass beads, pearl barley and whole peas) were measured at various bed heights. Analysis of the pressure fluctuation profiles leads to correlations that predict the minimum slugging velocity and slugging frequency, within experimental ranges. Results reveal that past correlations have little success in predicting the slugging characteristics for large particles. Particle shape plays an important role on the type of slug formed and therefore on the values of slugging frequency and minimum slugging velocity. Large particles with low sphericity formed wall slugs with high slugging frequencies and required the greatest amount of excess air to achieve slugging.On a mesure a des hauteurs de lits differentes les fluctuations de pression dans un lit garni de particules de type D (sable grossier, riz a grains longs, ble de printemps rouge, billes de verre de 10 mm, orge perle et pois entiers). L'analyse des profils de fluctuation des pressions a conduit a des correlations qui predisent la vitesse de bouillonnage minimum et la frequence du bouillonnage, dans les gammes experimentales. Les resultats revelent que les correlations passees reussissent ma1 a predire les caracteristiques de bouillonnage pour les grosses particules. La forme des particules joue un rde important sur le type de bouchon forme et donc sur les valeurs de frequence du bouillonnage et la vitesse de bouillonnage minimum. Les grosses particules ayant une petite sphericite foment des bouchons aux parois avec des frequences de bouillonnage elevees, et elles necessitent le plus grand exces d'air pour realiser le bouillonnage.Keywords: fluidization, slugging frequency, slugging, pressure measurements, group D particles. revious works on the hydrodynamic phenomenon of P slugging in fluidized beds have spanned the last three decades. The majority of these works concern themselves with the study of small (Type A and/or B) spherical or sandlike particles. There has been no work exclusively on the particle scale presented in this study. It will be shown that the relatively straight forward procedure of analyzing pressure fluctuations in a fluidized bed is an effective method for determining when the bed enters the slugging regime.Fluidization, in a gas-solid bed, begins when the weight of the particles is balanced by the buoyancy and drag caused by the flow of gas through the bed (Ho, 1983). If the superficial gas velocity is raised above the minimum fluidization velocity, aggregative fluidization is achieved which is characterized by two distinct phases that can be observed within the bed. With a firther increase in gas velocity, a phenomenon may be observed in which the bubbles coalesce and appear to occupy the whole cross-section of the fluidized bed column. These bubbles are referred to as slugs and this phenomenon is called slugging. The superficial gas velocity at the onset of slugging is termed the minimum slugging velocity and the rate at which the...

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“…T bubbling and the onset of slugging. Previous work on the dynamics of slugging have spanned the last three decades (Stewart and Davidson, 1967;Baeyens and Celdart, 1974; Darton et al, 1977;Ho et al, 1983;Noordergraaf et al, 1987;Kunii and Levenspiel, 1991;DiMattia et al, 1997). An increasingly common tool for the study of the slugging phenomenon is through time-series analysis of bed pressure fluctuations.…”

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confidence: 99%

Hydrodynamics of gas fluidized beds with mixture of group D and B particles

et al. 2002

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The dynamics of a gas‐solid fluidized bed containing Geldart Group D particles mixed with a small proportion of Geldart Group B particles are investigated using pressure fluctuations data. Time series analysis, using a variety of nonlinear dynamics tools, shows that the slugging present with Group D particles can be suppressed by the addition of a small proportion of Group B particles. The power spectra and the auto‐correlation function are used for a preliminary evaluation of dominant slug frequencies. It is shown that the bed fluidized with the mixture of Group D and B particles behaves in a less periodic manner and is dominated by more random bubble motion. On the other hand, the correlation integral is used to analyze the chaotic behaviour of the flow, through evaluation of the fractal structure of the reconstructed attractors. It is shown that the bed fluidized with Group D particles is characterized by a combination of steady slug motion and irregular particles motion. The behaviour of the fluidized bed of Group D/B particles mixture is characterized by a single correlation dimension for a wide range of fluidization velocities.

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The onset of slugging in gas—solid fluidized beds with large particles

Cited by 25 publications

References 0 publications

Flow regime diagram for vertical pneumatic conveying and fluidized bed systems

Flow regime diagram for vertical pneumatic conveying and fluidized bed systems

Slugging characteristics of group d particles in fluidized beds

Hydrodynamics of gas fluidized beds with mixture of group D and B particles

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