Particle velocity profiles and solid flow patterns in spouted beds

He, Youwei; Qin, Shaojin; Lim, C. J.; Grace, John R.

doi:10.1002/cjce.5450720402

Cited by 160 publications

(165 citation statements)

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“…The simulated results on particle velocity and profile for voidage in the spout and the annular regions obtained for the cylindrical spouted bed were compared with the experimental results obtained by He et al (1994). The simulated results on particle velocity and fountain height in the two-dimensional spouted bed were compared with experimental results obtained in the laboratory.…”

Section: Brazilian Journal Of Chemical Engineeringmentioning

confidence: 99%

“…The computational work was significantly reduced for axisymmetric gas-solids flows. The simulated velocity and voidage profiles were compared with results obtained in our laboratory (with a two-dimensional spouted bed using soybean seed) and by He et al (1994) (with a cylindrical spouted bed and glass sphere). The simulated results showed good agreement with the experimental data for both geometries studied.…”

Section: Abstract -mentioning

confidence: 99%

“…The first set of simulations represents the experiments carried out by He et al (1994) and the second, those obtained in our laboratory.…”

Section: Experimental Setup and Proceduresmentioning

confidence: 99%

“…The operational conditions used by He et al (1994) are shown in Table 1 and the spouted-bed vessel geometry in Figure 1.…”

Section: Conditions Of He Et Al (1994)mentioning

confidence: 99%

“…He et al (1994) used a fiber optic probe system to obtain the profiles for vertical particle velocities in the spout, annular and fountain regions of a fullcolumn spouted bed. Roy et al (1994) measured the particle velocities in a spouted bed using a γ-rayemitting particle tracking technique.…”

Section: Introductionmentioning

confidence: 99%

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A study of the fluid dynamics of the spouted bed using CFD

Duarte

Murata

Barrozo

2005

Braz. J. Chem. Eng.

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-The spouted bed has been used in drying, granulation, catalytic polymerization, residue treatment and coating of several materials. Its success is attributed to its solids circulation characteristics and excellent gas-particle contact. In this work the pattern of solids and gas flows in a spouted bed was numerically simulated using a Eulerian multiphase model. The computational work was significantly reduced for axisymmetric gas-solids flows. The simulated velocity and voidage profiles were compared with results obtained in our laboratory (with a two-dimensional spouted bed using soybean seed) and by He et al. (1994) (with a cylindrical spouted bed and glass sphere). The simulated results showed good agreement with the experimental data for both geometries studied.

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Section: Brazilian Journal Of Chemical Engineeringmentioning

confidence: 99%

Section: Abstract -mentioning

confidence: 99%

“…The first set of simulations represents the experiments carried out by He et al (1994) and the second, those obtained in our laboratory.…”

Section: Experimental Setup and Proceduresmentioning

confidence: 99%

“…The operational conditions used by He et al (1994) are shown in Table 1 and the spouted-bed vessel geometry in Figure 1.…”

Section: Conditions Of He Et Al (1994)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A study of the fluid dynamics of the spouted bed using CFD

Duarte

Murata

Barrozo

2005

Braz. J. Chem. Eng.

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Fluidization of micronic particles in a conical fluidized bed: Experimental and numerical study of static bed height effect

Bahramian¹,

Olazar²

2011

AIChE Journal

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in Wiley Online Library (wileyonlinelibrary.com).The numerical simulations and experimental data of bed hydrodynamics in a conical fluidized bed unit are compared. Experimental studies have been carried out in a bed containing TiO 2 particles belonging to A/C boundary of Geldart's classification with a wide particle-size distribution. Thus, pressure measurements and an optical fiber technique allowed determining the effect of static bed height on the fluidization characteristics of micronic particles. Numerical simulations have then been performed to evaluate the sensitivity of gas-solids drag models. The Eulerian multiphase model has been used with different drag models and three boundary conditions (BC) consisting of noslip, partial-slip, and free-slip. The numerical predictions using the Gidaspow drag model and partial-slip BC agreed reasonably well with the experimental bed pressure drop measurements. The simulation results obtained for bed expansion ratio show that the Gidaspow model with the free-slip BC best fit with the experimental data. V V C 2011 American Institute of Chemical Engineers AIChE J, 58: 730-744, 2012 Keywords: fluidization, hydrodynamics, CFD simulation, conical fluidized bed, drag models, boundary conditions Introduction Fluidization in conical vessels is a useful technique with a variety of applications in drying, [1][2][3][4] food processing, 5,6 pharmaceutical industry, [7][8][9][10] gasification and pyrolysis reactors, [11][12][13][14] and catalytic polymerization reactors. 15,16 A conical fluidized bed is a hybrid gas-solid contacting system, and therefore shares the characteristics of both fluidized and spouted beds. The naming of these types of beds in the literatures is often informed by their geometrical shape and the ratio of bed inlet diameter to particle size. 3,17 This bed provides means for the good mixing and circulation for small solid particles with a wide size distribution. Therefore, knowledge on the hydrodynamics of gas and particle flow in conical fluidized bed is essential for their design at both labscale and in industrial applications.Extensive research has been conduced on the fluidization behavior of classical powders in the 30 to 1000 lm size range 18 and, consequently, their behavior is relatively well understood. [19][20][21][22]23 studied the effect of fine particles beds with a wide size distribution on local voidage in a bench-scale conical fluidized bed. Their main conclusion is that fines form a monolayer around the relatively coarser particles and act as a lubricant, thus lowering the apparent bed viscosity. A lower apparent viscosity corresponded to smooth fluidization with fine bubbles. Geldart 19 argued that the effect observed could be explained by the reduction in mean particle diameter due to the addition of fines. Geldart's Correspondence concerning this article should be addressed to A. Bahramian at bahramian@profs.hut.ac.ir. 730AIChE Journal March 2012 Vol. 58, No. 3 measurements for Geldart A powder revealed a definite influence of size dis...

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Effect of slip boundary conditions on the simulation of microparticle velocity fields in a conical fluidized bed

2013

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The hydrodynamic performance of micrometric TiO 2 particles has been experimentally studied in a conical fluidized bed and the results compared with numerical simulations. Local solid velocities in the bed have been measured by means of an optical fiber technique under different operating conditions of particle loading and air velocity. The radial profiles of axial solid velocities have been simulated to assess the sensitivity of grid size, and different drag models, namely, those by Syamlal and O'Brien, Ahmadi and Ma, Arastoopour et al., and Gidaspow, for no-slip, partial-slip, and free-slip boundary conditions (BCs). The different drag models record almost similar results, but those provided by the Gidaspow and Ahmadi-Ma models, together with free-slip BCs, are in somewhat better agreement with the experimental data for conical fluidized beds with smooth walls. V C 2013 American Institute of Chemical Engineers AIChE J, 59: [4502][4503][4504][4505][4506][4507][4508][4509][4510][4511][4512][4513][4514][4515][4516][4517][4518] 2013 Keywords: conical fluidized bed, solid velocity, slip boundary conditions, numerical simulation, drag models IntroductionFluidized and spouted beds are extensively used for various industrial applications in pharmaceuticals, 1,2 drying, 3,4 food processing, 5 combustion, 6,7 pyrolysis, and catalytic polymerization. 8,9 A conical fluidized bed has the characteristics of both fluidized and spouted beds, being, therefore, suitable for handling agglomerating or sticky powders. This is particularly the case for the fluidization of fine particles with a wide size distribution corresponding to different groups of Geldart's classification. 10,11 Although many studies have been reported in the literature involving fluidized beds, [12][13][14][15] certain details of the hydrodynamic performance of conical fluidized beds are not fully understood, which is partially due to the few experimental data on the hydrodynamics of these beds. 16,17 Accordingly, the design and scaling-up of conical fluidized beds is not straightforward, given that bed geometry, the ratio of inlet diameter to bed height and operating conditions highly influence gas-solid flow regime. Furthermore, hydrodynamic parameters such as pressure drop, solid volume fraction, and velocity significantly affect the performance of the conical bed. Optimizing the performance of conical fluidized beds requires a thorough understanding of the mixing characteristics and interactions between the gas and solid phases. The standard noninvasive measurement techniques used for the determination of particle trajectories and velocities are as follows: pitot tube, 18 Laser-Doppler anemometry, 19 video technique, 20 radioactive particle tracking, 21 and particle image velocimetry. 22 Nevertheless, techniques based on an optical-fiber probe are also promising for this purpose. [23][24][25][26][27][28][29] In recent years, with the development of high performance computers, researchers have used numerical methods to study the flow behavior of fluidized...

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Particle velocity profiles and solid flow patterns in spouted beds

Cited by 160 publications

References 13 publications

A study of the fluid dynamics of the spouted bed using CFD

A study of the fluid dynamics of the spouted bed using CFD

Fluidization of micronic particles in a conical fluidized bed: Experimental and numerical study of static bed height effect

Effect of slip boundary conditions on the simulation of microparticle velocity fields in a conical fluidized bed

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