Effect of Tablet Deflectors in the Draft Tube of Fluidized/Spouted Bed Coaters

Subramanian, Ganeshkumar A.; Turton, Richard; Shelukar, Suhas; Flemmer, Luke

doi:10.1021/ie020577k

Cited by 20 publications

(11 citation statements)

References 14 publications

(28 reference statements)

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“…Compared with the fluidized bed, a spouted bed has several advantages, such as high efficiency of gas−solid contact, big capacity for handling a coarse particle, stable operation in a wide range of gas flow rates, small pressure drop, and little fluidizing air flow rate, etc. − However, due to several limitations of the conventional spouted bed (CSB), such as low annulus aeration and slow solids turnover, which is one of the reasons for the limited commercial use of spouted bed, the particles in the bed have a long residence time and poor efficiency of heat and mass transfer. Since the conventional spouted bed suffers from these shortcomings, many modified spouted bed designs have been proposed during the past decades, for example, multiple spouted beds, − spouted fluidized beds, , conical spouted beds, − draft tube spouted bed, − pulsed spouted bed, and rotating spouted bed. ,, Moreover, the particle hydrodynamic characteristics and gas−solid reaction models in these spouted beds have been studied. Lefroy and Davidson reported the dynamic behavior of the gas phase and solid phase in a spouted bed using a gas−solid flow model .…”

Section: Introductionmentioning

confidence: 99%

“…[1][2][3][4][5][6][7][8][9][10][11][12] However, due to several limitations of the conventional spouted bed (CSB), such as low annulus aeration and slow solids turnover, which is one of the reasons for the limited commercial use of spouted bed, 13 the particles in the bed have a long residence time and poor efficiency of heat and mass transfer. Since the conventional spouted bed suffers from these shortcomings, many modified spouted bed designs have been proposed during the past decades, 14 for example, multiple spouted beds, [15][16][17] spouted fluidized beds, 18,19 conical spouted beds, [20][21][22] draft tube spouted bed, [23][24][25][26][27] pulsed spouted bed, 13 and rotating spouted bed. 14,28,29 Moreover, the particle hydrodynamic characteristics and gas-solid reaction models in these spouted beds have been studied.…”

Section: Introductionmentioning

confidence: 99%

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Hydrodynamic Characteristics of a Novel Annular Spouted Bed with Multiple Air Nozzles

Gong

2006

Ind. Eng. Chem. Res.

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A novel spouted bed, namely, an annular spouted bed with multiple air nozzles, has been proposed for dryness, pyrolysis, and gasification of coal particulates. It consists of two homocentric upright cylinders with some annularly located spouting air nozzles between inner and outer cylinders. Experiments have been performed to study hydrodynamic characteristics of this device. The test materials studied are ash particle, soy bean, and black bean. Three distinct spouting stages have been examined and outlined with the hold-ups increase. In the fully developed spouting stage, three flow behaviors of particles have been observed and delimited. The effects of nozzle mode and spouting velocity on the maximum spouting height of the dense-phase region, spoutable static bed height, and spouting pressure drop in the bed have been investigated experimentally.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Hydrodynamic Characteristics of a Novel Annular Spouted Bed with Multiple Air Nozzles

Gong

2006

Ind. Eng. Chem. Res.

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“…Spouted-bed dryers also have been used for the coating of particles to obtain products with special properties. A special area of application for this type of equipment in the pharmaceutical industry is the coating of tablets , and other functional particles, − such as those used, for example, as injectable suspensions for cancer therapy . Drying is one of the stages that appears in all of the aforementioned technologies, and, in many cases, it limits the rate of process.…”

Section: Introductionmentioning

confidence: 99%

Point-by-Point Solution Procedure for the Computational Fluid Dynamics Modeling of Long-Time Batch Drying

Szafran

Kmieć

2005

Ind. Eng. Chem. Res.

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Further results of simulations of the drying kinetics in a spouted bed dryer with a draft tube (ICFB) will be presented in this paper. As noted earlier [Ind. Eng. Chem. Res. 2004, 43, 1113−1124], the Eulerian−Eulerian multifluid modeling approach was applied to predict gas−solid flow behavior. The heat- and mass-transfer model was coupled with computational fluid dynamics (CFD) code FLUENT 6.1, through application of user-defined functions (UDF). The falling rate period of drying was described by the linear and nonlinear lumped-parameter models. The new, robust “point-by-point” solution procedure was proposed to predict the kinetics of long-time batch processes and to overcome a lack of sufficient computational performance. The results of the simulations were compared with experimental data and with values obtained from various correlations. The drying kinetics during the constant and falling rate periods of drying of inorganic particles was predicted with sufficient accuracy and efficiency for engineering calculations. The mean relative errors were 3.24% and 19.8% for drying periods I and II, respectively. The biological texture of rapeseed caused higher discrepancies; however, for both types of grain, the results from the CFD simulations were more similar to the experimental data than to the values obtained from correlations. A CFD modeling technique, coupled with classical drying kinetics models, provided useful results for engineering purposes and allows use of the model throughout all phases of research and development.

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“…Spouted beds have developed as efficient fluid-particle contactors and have found numerous applications in the industry. Applications range from coal combustion and gasification (3)(4)(5), combustion of other fuels (6), catalytic reactors (7), thermal processing of solids (8), mixing of solids (9), and coating of particles (10) to drying of suspensions and pastes on inert solids (11)(12)(13), in addition to a variety of chemical reactions involving multiphase systems (14)(15)(16).…”

Section: Introductionmentioning

confidence: 99%

Assessment of the Energy Dissipation Parameters Inside the Draft Tube of a Liquid Spout-Fluid Bed

Erbil

Turan

2005

Environ. Sci. Technol.

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Spouted beds are fluid-particle contactors in which the fluid is introduced centrally through a nozzle instead of a distributor plate, resulting in a regular particle circulation pattern. To assess the suitability of such sytems to environmental engineering applications such as filter backwashing and biofilm systems, a priori knowledge of the energy dissipation parameters is essential. A new model is developed for evaluating the energy dissipation parameters inside the draft tube of spout-fluid beds. The shear stress, velocity gradient, and turbulence fluctuation parameters in the draft tube of a liquid spout-fluid bed are calculated with the help of an energy equation for flows carrying suspensions and the experimentally determined pressure losses inside the draft tube and compared with results for particulately fluidized beds. A spout-fluid bed with a draft tube provides higher shear stress inside the draft tube than a fluidized bed. The mean velocity gradient in the draft tube is comparable to and higher than in a fluidized bed and increases with solids fraction. The turbulence dissipation coefficient decreases very slightlywith increasing solids fraction for both systems. Consequently, according to the model calculations, a spout-fluid bed with a draft tube can be an alternative to the classical fluidized bed filter backwashing system.

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Effect of Tablet Deflectors in the Draft Tube of Fluidized/Spouted Bed Coaters

Cited by 20 publications

References 14 publications

Hydrodynamic Characteristics of a Novel Annular Spouted Bed with Multiple Air Nozzles

Hydrodynamic Characteristics of a Novel Annular Spouted Bed with Multiple Air Nozzles

Point-by-Point Solution Procedure for the Computational Fluid Dynamics Modeling of Long-Time Batch Drying

Assessment of the Energy Dissipation Parameters Inside the Draft Tube of a Liquid Spout-Fluid Bed

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