Hydrodynamic Characteristics of Fluidized Beds  Containing Large Polydispersed Particles

Tannous, Kátia; Hémati, Mehrdji; Laguérie, C.

doi:10.1590/s0104-66321998000100007

Cited by 9 publications

(5 citation statements)

References 5 publications

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“…When there are solids of different density and/or size present, the net effect of all of these mixing processes can lead to segregation of the different solids into distinct spatial zones. Many previous studies − have examined binary as well as continuous distributions for segregation tendencies. A recent overview of fluid bed segregation summarizes this work and points out that there is still no clear understanding of the details of this process.…”

Section: Introductionmentioning

confidence: 99%

Observed Mixing Behavior of Single Particles in a Bubbling Fluidized Bed of Higher-Density Particles

Halow

Holsopple

Crawshaw

et al. 2012

Ind. Eng. Chem. Res.

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We report experimental observations of the dynamic behavior of single, magnetically tagged 3–4 mm particles varying in density from 0.55 g/cm3 to 1.2 g/cm3 as they migrate freely in a bubbling air-fluidized bed of 177–250 μm glass beads of 2.5 g/cm3 density over a range of air flows. The densities of the tracer particles (made by imbedding small magnets in wooden particles) were chosen to span a range typical for many biomass materials and exhibited both segregated and well-mixed behavior. Using high-speed measurements from externally mounted magnetic probes, we were able to reconstruct three-dimensional spatial and temporal information about the tracers’ trajectories over periods of five minutes. Based on this information, we describe general trends in how the tracers moved and redistributed themselves as functions of their density, fluidization air flow, and the overall concentration of low density particles present. One key finding was that the time average vertical probability distribution of the tracer particles locations is consistent with a Weibull distribution. The effective Weibull parameters appear to vary systematically with the degree of fluidization and particle density. Also, we observed that temporal autocorrelations in the vertical position of the tracer particles vary systematically with fluidization intensity and reveal important information about the dominant bed circulation time scales. Our results suggest that it may be possible to develop relatively simple statistical models or correlations for describing the spatial distribution and circulation of mm sized particles in bubbling beds of this type. Such tools should be useful for simulating some types of fluidized biomass processing and for validating kinetic-theory models of fluidized bed systems.

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Section: Introductionmentioning

confidence: 99%

Observed Mixing Behavior of Single Particles in a Bubbling Fluidized Bed of Higher-Density Particles

Halow

Holsopple

Crawshaw

et al. 2012

Ind. Eng. Chem. Res.

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“…The complete fluidization velocity (U fc ), defined as the minimum air velocity at which all the particles are suspended (Tannous et al, 1998;Gauthier et al, 1999), was determined for each condition. To ensure that all the particles were suspended, particularly in the experiments involving a binary particle size distribution, the air fluidization velocity was kept at a value 10% above U fc .…”

Section: Methodsmentioning

confidence: 99%

Effects of binary particle size distribution on the fluid dynamic behavior of fluidized, vibrated and vibrofluidized beds

Daleffe

Ferreira

Freire

2008

Braz. J. Chem. Eng.

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-In this work the effects of particle size distribution on the dynamics and segregation patterns in fluidized, vibrated and vibrofluidized beds were investigated. A binary particle size distribution and a reference one composed of glass spheres with a mean Sauter diameter of 2.18×10 -3 m were tested. The experimental setup consisted basically of a circular glass chamber with a height of 0.50 m and a diameter of 0.114 m, operated in the fluidized bed mode ( = 0.00), in either vibrated or vibrofluidized bed modes ( = 2.00). The pressure drops in the fluidized and vibrofluidized beds were not significantly affected by the binary particle size distribution. Well-defined segregation patterns occurred in fluidized and vibrated beds with small particles concentrating at the top and large particles at the bottom in the first situation and the reverse in the second one. Segregation patterns in vibrofluidized beds depended on the values of vibration parameters. Segregation in vibrofluidized and vibrated beds was minimized by operating at a high amplitude of vibration.

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“…Depending on the kinds of biomass particles, these determinations can be distinct, mainly referring to the segregation velocity (gray patterned area). The approach was proposed firstly by Punčochář, Drahoš, Čermák, and Selucký [34] for homogeneous particles, and later applied to polydispersed particles [35] and to binary mixtures [9]. In this case, the characteristic velocities are determined according to the inflections in the curve schematized in Fig.…”

Section: Experimental Techniquesmentioning

confidence: 99%

Experimental Study of Fluid Dynamic Behavior of Biomass Particles in Fluidized Beds: A Review

Tannous

Mitri

Mizonov³

2018

IVUZKKT

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Decease of natural resources and increase of price of fossil fuels at growing energy consumption, toughening of ecological standards and necessity of the increase of the level of energetics diversification motivates mankind to more wide usage of renewable energy resources including the solid fuel of biological origin. The potential of biofuel usage is rather considerable because the energy equivalent of the biomass harvest on the land exceeds the worldwide energy consumption several times as much. The biomass application as a renewable fuel is already a reality worldwide with the development of policies and technologies that turn viable the transformation of biomass into energy. The aims of this work is to present a literature experimental review on the studies concerning to the use of fluidized beds taking into account their design and scale-up. Initially, the usual solid particle terminology and some important biomass properties are presented. A brief description of conversion technologies and the fluidization phenomena are introduced, followed by an explanation of the different experimental techniques. The characteristic velocities (initial, apparent, of segregation, and complete) are discussed based on different biomass properties, as well as a number of empirical correlations for these velocities are described. Finally, some considerations are made about characteristic bed porosities (apparent and complete) and bed expansion. Based on the literature analysis, an improvement has been done on the understanding of the biomass fluidization phenomena, however, further research is needed to comprehend the effect of biomass characteristics on the bed operational parameters, besides more accurate and general correlations must be developed to improve these technologies. For citation: Tannous K., De Mitri A.G., Mizonov V. Experimental study of fluid dynamic behavior of biomassparticles in fluidized beds: a review. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 9-10. P. 4-14

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Hydrodynamic Characteristics of Fluidized Beds Containing Large Polydispersed Particles

Cited by 9 publications

References 5 publications

Observed Mixing Behavior of Single Particles in a Bubbling Fluidized Bed of Higher-Density Particles

Observed Mixing Behavior of Single Particles in a Bubbling Fluidized Bed of Higher-Density Particles

Effects of binary particle size distribution on the fluid dynamic behavior of fluidized, vibrated and vibrofluidized beds

Experimental Study of Fluid Dynamic Behavior of Biomass Particles in Fluidized Beds: A Review

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