The fluidization process of binary mixtures of solids: Development of the approach based on the fluidization velocity interval

Formisani, Brunello; Girimonte, Rossella; Longo, T.

doi:10.1016/j.powtec.2007.10.003

Cited by 78 publications

(69 citation statements)

References 15 publications

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“…This relationship is formally identical to that obtained by a different approach and validated by experimental results relevant to a large number of two-solid systems [4][5][6], so that no further check of its accuracy (easily recognizable in the figures of this section) is here required. More interesting is that the present investigation provides a better understanding of the mechanism by which in any mixture of two solids one of the two components enters the suspended state at a velocity higher than its umf, whereas the other achieves fluidization at uff, a velocity however lower than its umf.…”

Section: Effects Of the Interaction Between Components On The Mechanisupporting

confidence: 71%

“…The pioneering studies of Chen and Keairns [1], Gelperin and Einstein [2] and Vaid and Sen Gupta [3] first revealed that fluidization of binary and ternary beds is a process that has place gradually. More recently, the dependence of both uif and uff on the main variables which determine the fluidization pattern (solid properties, mixture composition and bed geometry) has been investigated by Formisani et al [4][5][6], who analyzed the behaviour of a large number of twocomponent mixtures. These studies have provided experimental evidence that the values of uif and uff are located in between the minimum fluidization velocities of the system components.…”

Section: Introduction and Previous Workmentioning

confidence: 99%

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The interaction between mixture components in the mechanism of binary fluidization

2014

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The interaction between components during segregating fluidization of two-solid mixtures is shown to be an intrinsic feature of their mechanism of suspension. Separate force balances on either mixture component lead to assessing the individual contribution of the two solids to the total pressure drop. An analytical expression for the interaction force is thus obtained that explains why the complete fluidization of the mixture is possible at a velocity lower that the higher umf of the two components and how the roles of 'flotsam' and 'jetsam' are attributed to them during the process of segregation.The theoretical expressions for the initial and final fluidization velocity of a binary mixture provided by this more insightful method of analysis are identical to those discussed in previous works and validated by a wide variety of experimental results.

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Section: Effects Of the Interaction Between Components On The Mechanisupporting

confidence: 71%

Section: Introduction and Previous Workmentioning

confidence: 99%

The interaction between mixture components in the mechanism of binary fluidization

2014

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“…As comprehensively discussed in a recent work, 8 however, any criterion aiming to establish an equivalence between a two-component bed and a monosolid system with the same u mf gives place to a misleading approach, fated to overlook important aspects of the binary fluidization phenomenology. The most important of them is the gradual nature of the process, which results from the interaction between the progress of particle suspension and that of the segregation-remixing phenomena to which the two solids are subjected.…”

Section: Introductionmentioning

confidence: 99%

Fluidization of mixtures of two solids differing in density or size

2010

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The complex mechanism by which homogeneous mixtures of two solids achieve fluidization is subjected to theoretical analysis, to elaborate relationships capable to provide their ''initial'' and ''final fluidization velocity'' u if and u ff , i.e., the limits that encompass the suspension process. The article shows how the equation that describes the force equilibrium of fluidization can be rewritten in forms that account for the distribution of the components of density-or size segregating mixtures during the transition to the fluidized state. This approach leads to the theoretical expression of u if and u ff of either type of system, whose differences of behavior are correctly reproduced by accounting for the voidage reduction typical of beds of particles of different size. The comparison with experimental results at varying mixture composition demonstrates that the equations give a coherent interpretation of the dependence of the fluidization velocity interval of two-solid mixtures on the principal variables of interest.

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“…Clarke et al (2005) found that mixtures of sawdust and 0.322-mm glass spheres can be completely mixed when fluidized, but mixtures of sawdust and 0.516-mm glass spheres were either partially or completely mixed, depending upon gas velocity in the fluidized bed. The fluidization of biomass/inert particles mixtures is categorized as binary mixture fluidization, and current understanding of the mechanism of multicomponent fluidization is still admittedly unsatisfactory (Formisani et al 2008). Segregation is a distressing but common problem in mixture fluidization that negatively affects the performance of fluidized-bed units in which chemical reactions take place (Zhong et al 2008).…”

Section: Introductionmentioning

confidence: 99%

Fluidization Behavior of Biomass Particles and its Improvement in a Cold Visualized Fluidized Bed

Wu¹,

Li²,

Song³

et al. 2017

BioResources

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The fluidization behavior in a fluidized bed was visualized at room temperature under different conditions for two typical lignocellulosic biomass materials (rice husk and walnut shell) as representative samples of herbage and xylophyta, respectively. The effects of initial bed height, moisture content, and addition of sand particles on the quality of fluidization were analyzed, and the optimal operating parameters were determined. The initial bed height had a negligible effect on the minimum fluidization velocity but an obvious influence on bed stability. In addition, with an increase in moisture content, the minimum fluidization velocity showed the growth of an S-shaped curve and a constant decrease in the fluidization index in the fluidized region. Fluidization when performed on binary mixtures indicated that the proportion of sand-3 (60 to 80 mesh) in biomass and sand-3 in mixtures is a main factor contributing to the fluidizing quality of a bed. With larger proportions of sand-3, the fluidizing quality of the bed improved. Meanwhile, the differences in fluidization behavior between rice husk and walnut shell have been determined.

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The fluidization process of binary mixtures of solids: Development of the approach based on the fluidization velocity interval

Cited by 78 publications

References 15 publications

The interaction between mixture components in the mechanism of binary fluidization

The interaction between mixture components in the mechanism of binary fluidization

Fluidization of mixtures of two solids differing in density or size

Fluidization Behavior of Biomass Particles and its Improvement in a Cold Visualized Fluidized Bed

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