Computer simulations of gas–solid flow in spouted beds using kinetic–frictional stress model of granular flow

Huilin, Lu; He, Yaning; Wentie, Liu; Ding, Jing; Gidaspow, Dimitri; Bouillard, Jacques

doi:10.1016/j.ces.2003.10.018

Cited by 152 publications

(65 citation statements)

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“…Solid velocities in both the spout and the annular zones decrease as the radial distance from the center of the bed is higher and the velocity profiles in the two zones become flatter until zero velocity is recorded at the top of the fountain, and the particles then fall onto the annular zone. These results are qualitatively similar to those obtained by Goldschmidt et al, 15 Kmiec, 16 Olazar et al,8,26,27 and Huilin et al 68 for conical-cylindrical spouted beds and jet-spouted beds.As static bed height is increased from 0.012 m (Figure 14) to 0.024 m (Figure 15) and then to 0.048 m (Figure 16), once the spout has been formed the air in all cases passes preferentially through this central bed zone. As observed, the mean axial solid velocities at the bottom (at z 5 0.05 m) for a high air velocity ( Figures 14D-16D) are different for the three static bed heights studied, 0.012, 0.024, and 0.048 m. Visual observations reveal that high static bed heights cause particle agglomeration.…”

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confidence: 94%

“…The formation of the spout in the center and in the annulus near the walls is also observed. 23,65,68 The spout and annular zones are not defined in conical fluidized beds, and a vigorous particle motion is observed at high airflow velocities, as shown in Figures 12D-13D. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.]…”

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confidence: 95%

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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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confidence: 95%

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

2013

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“…Following this approach, studies have been conducted to expand the dimensionless-groups of spouted beds by adding the restitution coefficient (e s , which accounts for the inelasticity of particles collision) or the friction of particles [199]. This parameter becomes crucial due to the important role that the interparticle collisions play in the fountain and spout regions.…”

Section: Conicalmentioning

confidence: 99%

Modelling of Spouted and Spout-Fluid Beds: Key for Their Successful Scale Up

et al. 2017

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The development of robust mathematical models could provide the necessary tools for a more rapid, efficient, and reliable spouted bed technology development. Computer simulations can be very useful to aid this design and scale-up process: firstly, they can contribute to obtain a fundamental insight into their complex dynamic behavior by understanding the elementary physical principles such as drag, friction, dissipation etc.; secondly, the simulations can be used as a design tool where the ultimate goal is to have a numerical model with predictive capabilities for gas-particle flows at engineering scale. Clearly, one single simulation method will not be able to achieve this goal, but a hierarchy of methods modelling phenomena on different length and time scales can achieve this. The most fruitful approach will be when they are simultaneously followed, so that they can mutually benefit from each other. In this sense, this paper presents a review of the current state of the art of modelling on spouted and spout-fluid beds through an analysis of recent literature following a multiscale approach (molecular and particle, lab, plant and industrial scale). The main features of the different scales together with their current limits are discussed and specific topics are highlighted as paths that still need to be explored. In summary, the paper aims to define the theoretical setline and the basis of improvement that would lead to a robust multiscale model with solid links between micro and macroscopic phenomena. If done with the correct balance between accuracy and computational costs it will gear SB towards their reliable and successful implementation.

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“…Using this term leads to better results in dense gas-solid fluidized bed [15,[33][34][35]. Similar to several researchers, the restitution coefficient of 0.9 was used in the current simulation [24,25,36].…”

Section: Table 2 Closure Relationships For Two-fluid Modelmentioning

confidence: 95%

CFD simulation of gas-solid bubbling fluidized bed containing FCC particles

Hosseini

Rahimi

Zivdar

et al. 2009

Korean J. Chem. Eng.

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The hydrodynamics of a bubbling gas-solid fluidized bed of 57.4 µm FCC particles was simulated by using a state-of-the-art two-fluid model integrating the kinetic theory of granular flow for particulate phase stresses. The overestimation of the bed expansion was resolved by using a suitable scale factor in the drag model as suggested by McKeen and Pugsley (T.R. McKeen, T.S. Pugsley, Powder Technol., 129, 139 (2003)). This study showed that the method was appropriate in simulation of a gas-solid fluidized bed of Geldart A particles at high gas velocities (0.3 to 0.61 m/s). The reduction of computational time especially for simulation of large-scale systems was achieved. The time-averaged local voidage was compared with the experimental data and the trend of varying several parameters on the hydrodynamic of the bed was investigated. The simulation results showed both qualitative and quantitative agreement with the literature.

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Computer simulations of gas–solid flow in spouted beds using kinetic–frictional stress model of granular flow

Cited by 152 publications

References 32 publications

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

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

Modelling of Spouted and Spout-Fluid Beds: Key for Their Successful Scale Up

CFD simulation of gas-solid bubbling fluidized bed containing FCC particles

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