The interaction between mixture components in the mechanism of binary fluidization

Formisani, Brunello; Girimonte, Rossella; Vivacqua, Vincenzino

doi:10.1016/j.powtec.2014.06.007

Cited by 16 publications

(11 citation statements)

References 11 publications

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“…In this way this study extends to confined fluidized beds the approach originally proposed for two-solid mixtures whose components undergo fluidization simultaneously [6]. With both categories of systems the role played by solid-solid interaction in determining the mechanism of fluidization is crucial, although the nature of this interaction is not the same.…”

Section: Data Ofmentioning

confidence: 86%

“…In a previous work [6], the term fi in Eq. (1), written for the two solid species, comprised the pure drag force exerted by the fluid as well as the interaction forces between the two solids.…”

Section: Separate Force Balancesmentioning

confidence: 99%

“…In the force balances for the two solids, the drag force on each of them has been obtained from the Carman-Kozeny equation and partitioned according to their respective surface fractions [6].…”

Section: Separate Force Balancesmentioning

confidence: 99%

“…A distinctive feature of these systems is the often unavoidable tendency of the solid components to segregate, giving rise to a non-homogeneous internal composition of the bed [1][2][3][4][5]. It has recently been shown that a key-role is played by solid-solid interactions in the mechanisms of binary fluidization [6]. In that work, assessing the component contribution to the total pressure drop allowed writing separate force balances on each component of the multiphase system.…”

Section: Introductionmentioning

confidence: 99%

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Extension of the model of binary fluidization to beds confined in a packing of coarse spheres

2016

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The prediction of the minimum fluidization velocity of beds of Geldart's group B particles confined in a packed bed of coarse spheres can be achieved by extending to this peculiar type of systems the theory developed for modelling the behaviour of segregating beds of simultaneously fluidized solids.The approach is based on separate force balances on the fluid and the fine solids, capable to account for the peculiar nature of solid-solid interaction in a confined fluidized bed. Its validation is fulfilled by an extended investigation conducted in two columns (5 and 10 cm OD) packed with a fixed bed of 4.1 mm lead shots or 11 mm glass beads. The effect of particle size on the fluidization regime is investigated by comparing the results provided by experiments in which various cuts of glass ballotini, ranging from 100 to nearly 600 µm, are fluidized in two packings of fixed spheres; possible differences of behaviour due to particle density are analysed by series of experiments employing particles of ceramics, zirconium oxide, steel and bronze of the same diameter.The results obtained confirm the effectiveness of the approach followed, in which an important role is played by the indirect interaction between the two solid phases. KEYWORDSConfined-fluidized beds; bubble-free fluidization; packed-fluidized beds; binary fluidization; solid interaction. 1.

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Section: Data Ofmentioning

confidence: 86%

Section: Separate Force Balancesmentioning

confidence: 99%

Section: Separate Force Balancesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Extension of the model of binary fluidization to beds confined in a packing of coarse spheres

2016

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“…For both liquid and gas fluidization of non‐porous monocomponent solids of uniform size, shape, and density, the prediction of minimum fluidization velocity has been thoroughly investigated. For multicomponent solids, however, full fluidization is initiated gradually over a range of fluid velocity rather than abruptly at a single value as for monocomponents, and this velocity range has to date been relatively under‐investigated. A notable exception is the work of Formisani et al on gas fluidization of binary mixtures of Geldart type B particles. These investigators have mathematically modelled the velocity interval involved, starting with the initial fluidization velocity u if and terminating with the final fluidization velocity u ff , and have thoroughly verified their model experimentally for different binary combinations of particle sizes, densities, and shapes.…”

Section: Introductionmentioning

confidence: 99%

Liquid velocity interval for minimum liquid fluidization of binary solids mixtures

Vinnenberg

Ellis

et al. 2016

Can J Chem Eng

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The gas velocity interval for initiating gas fluidization of binary mixtures of Geldart type B particles has been thoroughly investigated experimentally and theoretically by Formisani et al.[2–6] The same approach has now been applied in our laboratory to liquid fluidization of binary macro‐solids. Experimental results for water fluidization in a 190.5 mm diameter column of initially well mixed packed beds, consisting of different volumetric fractions of 1.91 mm and 4.54 mm glass spheres of density 2510 kg/m3, are well predicted by the methods of Formisani et al., whether the equations are based on random‐dense voidages as practiced by that group, or based on random‐loose voidages as commonly used for monocomponent solids.

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Dynamics of segregation and fluidization of binary mixtures in a cylindrical fluidized bed

2019

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Dynamics of segregation and fluidization of unary particles and binary mixtures in a cylindrical fluidized bed is investigated using temporally– and spatially–resolved measurements of solids volume fraction (αs) performed using Electrical Capacitance Tomography (ECT). Through the comparison with high‐speed imaging, we have shown that ECT can be used to measure the segregation behavior in cylindrical fluidized beds quantitatively. ECT measurements have been used further to quantify the effects of mixture composition, particle–diameter ratio, and superficial gas velocity on the bed segregation behavior. Dynamics of fluidization behavior is characterized using the time–evolution of local αs fluctuations, corresponding frequency distribution, and bubble size distribution. Further, a relation between the measured variance of αs fluctuations at different radial locations and corresponding flow structures under different fluidization conditions is established. The present work helps to understand dynamics of segregation and fluidization of binary mixtures and to provide a database for validation of Eulerian multifluid CFD models.

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The interaction between mixture components in the mechanism of binary fluidization

Cited by 16 publications

References 11 publications

Extension of the model of binary fluidization to beds confined in a packing of coarse spheres

Extension of the model of binary fluidization to beds confined in a packing of coarse spheres

Liquid velocity interval for minimum liquid fluidization of binary solids mixtures

Dynamics of segregation and fluidization of binary mixtures in a cylindrical fluidized bed

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