Catalyst Suspension in Gas-Agitated Tubular Reactors

Cova, D.

doi:10.1021/i260017a005

Cited by 80 publications

(40 citation statements)

References 5 publications

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“…A sedimentation-dispersion (SD) model (Cova, 1966) is applied for this purpose. Since the experiments were performed in batch mode with respect to solids, the SD model can be reduced to (24) Sedimentation velocity and axial dispersion coefficient are calculated according to Kato et al (Table 4).…”

Section: Aiche Journalmentioning

confidence: 99%

Description of three‐phase filtration with a novel dimensionless number

1998

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Section: Aiche Journalmentioning

confidence: 99%

Description of three‐phase filtration with a novel dimensionless number

1998

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“…The boundary conditions for the description of the solids concentration distribution in a slurry bubble column have been a point of controversy for several years (Cova, 1966;Yamanaka et al, 1970;Suganuma and Yamanishi, 1966;Kato et al, 1972;Smith and Ruether, 1985;Smith et al, 1986). Cova and Yamanaka et al held that the solids concentration a t the top of the column is the same as the effluent or feed concentration.…”

Section: Solids Concentration At Top Of Columnmentioning

confidence: 99%

Gas and solids behavior in a baffled and unbaffled slurry bubble column

et al. 1987

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New data and analyses are presented for describing gas and solids behavior in a slurry bubble column. Axial solids concentration and bubble size distributions were measured in a 0.108 m ID slurry bubble column apparatus operated at steady state conditions. The column was operated with and without internal baffles. The slurry and gas superficial velocities ranged from 0.0077 to 0.009 m / s and from 0.031 to 0.24 m/s, respectively. The solid phase consisted of glass spheres in a narrow size range with a mean diameter of 96.5 pm; the liquid phase consisted of tap water.With a one-dimensional sedimentation-dispersion model, the data have been used to predict average solids loadings and axial distributions of the solids for specified operating conditions. Local bubble size and concentration measurements indicate that the slurry bubble column was operated in the churn-turbulent flow regime throughout the entire range of operating conditions used in this study. The impact of internal baffles and solids concentration on the gas and solids behavior is discussed.

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“…These, in turn, depend upon (a) solid and liquid phase properties: density, particle size, particle size distribution, viscosity, interfacial tension, and wettability; (b) relative concentrations of solid and liquid phases; and (c) relative velocities of gas and liquid phases. Previous investigators have described the behavior of solids in an SBC by a one-dimensional sedimentation dispersion model (Cova, 1966;Suganuma and Yamanishi, 1966). Several variations of the model for the steady state conditions have been summarized by Smith and Ruether (1984).…”

Section: Introductionmentioning

confidence: 99%

“…Several variations of the model for the steady state conditions have been summarized by Smith and Ruether (1984). The basic assumption made in this model (Cova, 1966) is of uniform particle size, although in most industrial applications the particle size is not uniform. The effect of particle size distribution on hydrodynamic behaviors of an SBC reactor has received very little attention in the literature (Reilly et al, 1982).…”

Section: Introductionmentioning

confidence: 99%

Modified sedimentation‐dispersion model for solids in a three‐phase slurry column

et al. 1986

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Solids distribution data for a three-phase, batch-fluidized slurry bubble column (SBC) are presented, using air as the gas phase, pure liquids and solutions as the liquid phase, and glass beads and carborundum catalyst powder as the solid phase. Solids distribution data for the three-phase SBC operated in a continuous mode of operation are also presented, using nitrogen as the gas phase, water as the liquid phase, and glass beads as the solid phase. A new model to provide a reasonable approach to predict solids concentration distributions for systems containing polydispersed solids is presented. The model is a modification of standard sedimentation-dispersion model published earlier. Empirical correlations for prediction of hindered settling velocity and solids dispersion coefficient for systems containing polydispersed solids are presented.A new method of evaluating critical gas velocity (CGV) from concentrations of the sample withdrawn at the same port of the SBC is presented. Also presented is a new mapping for CGV which separates the two regimes in the SBC, namely, incomplete fluidization and complete fluidization. D.N. Smith and J.A. Ruether SCOPEFormulation of a mathematical model describing the behavior of solid particles in a slurry bubble column reactor usually includes the transport mechanisms of solids dispersion and hindered settling. In general, material balances for the axial variation of solids concentration is considered in model formulations. Unfortunately, the boundary conditions associated with analytical expressions describing axial solids concentration distributions are very difficult to obtain, either experimentally or theoretically. Moreover, in most instances slurry bubble column reactors contain solids having a particle size distribution that may not be uniformly dispersed throughout the reactor. For these reasons, the development of a mathematical model that has a closed form solution and considers the effect of particle size distribution would be desirable for improved understanding of solids behavior in a slurry bubble column reactor.This study aims to investigate solids behavior in a slurry bubble column with monodispersed and polydispersed particle systems. A strategy is developed to analyze axial solids concentration distribution of polydispersed particles and boundary conditions are formulated that provide for a closed form solution of the sedimentation-dispersion model. The velocity required to completely suspend the particles (critical gas velocity) is implicitly obtained from the present model. Thus the model is useful for determining the range of operating conditions where completely suspended particles exist, and further addresses the hydrodynamic and mass transfer properties of slurry reactors containing polydispersed solids. CONCLUSIONS AND SIGNIFICANCEA modified sedimentation-dispersion model has been used mainly to study the effect of polydispersed been developed describing axial solids concentration solids on axial solids concentration and particle size distributions in ...

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Catalyst Suspension in Gas-Agitated Tubular Reactors

Cited by 80 publications

References 5 publications

Description of three‐phase filtration with a novel dimensionless number

Description of three‐phase filtration with a novel dimensionless number

Gas and solids behavior in a baffled and unbaffled slurry bubble column

Modified sedimentation‐dispersion model for solids in a three‐phase slurry column

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