Three dimensional multi fluid modeling of Geldart B bubbling fluidized bed with complex inlet geometries

Purpose The purpose of this study is to assess the performance of ANSYS Fluent® and OpenFOAM®, at their current state of development, to study the relevant bubbling fluidized bed (BFB) characteristics with Geldart A, B and D particles. Design/methodology/approach For typical Geldart B and D particles, both a three-dimensional cylindrical and a pseudo-two-dimensional arrangement were used to measure the bed pressure drop and solids volume fraction, the latter by digital image analysis techniques. For a typical Geldart A particle, specifically to examine bubbling and slugging phenomena, a 2 m high three-dimensional cylindrical arrangement of small internal diameter was used. The hydrodynamics of the experimentally investigated BFB cases were also simulated for identical geometries and operating conditions using OpenFOAM® v6.0 and ANSYS Fluent® v19.2 at identical mesh and numerical setups. Findings The comparison between experimental and simulated results showed that both ANSYS Fluent® and OpenFOAM® provide a fair qualitative prediction of the bubble sizes and solids fraction for freely-bubbling Geldart B and D particles. For Geldart A particles, operated in a slugging mode, the qualitative predictions are again quite fair, but numerical values of relevant slug characteristics (length, velocity and frequency) slightly favor the use of OpenFOAM®, despite some deviations of predicted slug velocities. Originality/value A useful comparison of computational fluid dynamics (CFD) software performance for different fluidized regimes is presented. The results are discussed and recommendations are formulated for the selection of the CFD software and models involved.

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ASYMPTOTIC POWER SPECTRUM ANALYSIS OF CHAOTIC BEHAVIOR IN FLUIDIZED BEDS

International Journal of Bifurcation and Chaos ◽

10.1142/s021812749400023x ◽

1994 ◽

Vol 04 (02) ◽

pp. 327-341 ◽

Cited By ~ 4

Author(s):

JIANMIN DING ◽

SHIU-WING TAM

Keyword(s):

Power Spectrum ◽

Fluidized Bed ◽

Power Law ◽

Fluidized Beds ◽

Chaotic Behavior ◽

Three Dimensional ◽

Nonlinear Behavior ◽

Asymptotic Power ◽

Bubbling Fluidized Bed ◽

Fluidization Condition

The nonlinear behavior of fluidized beds is analyzed quantitatively using an asymptotic power spectrum method. A model based on kinetic theory is used to compute the voidage signals in a two-dimensional bubbling fluidized bed with a fluidization condition of U/Umf=4, where U is the fluidizing velocity and Umf is the minimum fluidizing velocity. The data for power versus frequency in the asymptotic frequency regime are shown to obey a power-law falloff. This means that the bubbling fluidization under such a fluidization condition cannot be a low-dimensional strange attractor. Pressure fluctuation data, obtained from a three-dimensional bubbling fluidized bed, are also analyzed and clearly show the power-law falloff. This is consistent with previous findings in that the correlation dimension for these data cannot be small (i.e., 2 or 3). The differences between our findings and others are discussed.

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Three-dimensional two-fluid modeling of a cylindrical fluidized bed and validation of the Maximum Entropy method to determine bubble properties

Chemical Engineering Journal ◽

10.1016/j.cej.2014.10.014 ◽

2015 ◽

Vol 262 ◽

pp. 628-639 ◽

Cited By ~ 15

Author(s):

C. Sobrino ◽

A. Acosta-Iborra ◽

M.A. Izquierdo-Barrientos ◽

M. de Vega

Keyword(s):

Maximum Entropy ◽

Fluidized Bed ◽

Maximum Entropy Method ◽

Three Dimensional ◽

Entropy Method ◽

Fluid Modeling ◽

Two Fluid ◽

Bubble Properties

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Two- and three-dimensional CFD modeling of Geldart A particles in a thin bubbling fluidized bed: Comparison of turbulence and dispersion coefficients

Chemical Engineering Journal ◽

10.1016/j.cej.2011.04.007 ◽

2011 ◽

Vol 171 (1) ◽

pp. 301-313 ◽

Cited By ~ 58

Author(s):

Benjapon Chalermsinsuwan ◽

Dimitri Gidaspow ◽

Pornpote Piumsomboon

Keyword(s):

Fluidized Bed ◽

Three Dimensional ◽

Cfd Modeling ◽

Dispersion Coefficients ◽

Bubbling Fluidized Bed

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Computation of the mass transfer coefficient of FCC particles in a thin bubbling fluidized bed using two- and three-dimensional CFD simulations

Chemical Engineering Science ◽

10.1016/j.ces.2011.07.042 ◽

2011 ◽

Vol 66 (22) ◽

pp. 5602-5613 ◽

Cited By ~ 17

Author(s):

Benjapon Chalermsinsuwan ◽

Pornpote Piumsomboon

Keyword(s):

Mass Transfer ◽

Transfer Coefficient ◽

Mass Transfer Coefficient ◽

Fluidized Bed ◽

Three Dimensional ◽

Cfd Simulations ◽

Bubbling Fluidized Bed

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3-D Modeling of Liquid Injection into Fluidized Beds

International Journal of Chemical Reactor Engineering ◽

10.2202/1542-6580.1178 ◽

2004 ◽

Vol 2 (1) ◽

Cited By ~ 7

Author(s):

Joachim Werther ◽

Stefan Bruhns

Keyword(s):

Fluidized Bed ◽

Flow Structure ◽

Three Dimensional ◽

Fluidized Bed Reactors ◽

Three Dimensional Model ◽

Liquid Injection ◽

Bubbling Fluidized Bed ◽

Solids Mixing ◽

Semi Empirical ◽

Bubble Splitting

A three-dimensional model has been developed to describe the injection of liquid reactants into fluidized bed reactors operating in the bubbling fluidized bed regime. The model considers the processes of liquid transport and evaporation in the vicinity of the point of injection. The underlying idea, which is supported by previous measurements, is that the particles in the dense suspension phase are wetted by the liquid or gas-liquid spray. The wetted particles are subsequently dried while they are following the gross solids circulation within the bed. The model considers the flow structure of the bubbling fluidized bed and the solids mixing with the aid of a hybrid model which combines semi-empirical models for bubble growth by coalescence and for bubble splitting with a CFD approach for the continuous emulsion phase surrounding the bubbles. Submodels for heat and mass transfer are used to describe the temperature and concentration fields in the vicinity of the injection nozzle and the drying process of the wetted particles with the resulting release of the vaporized injection liquid. The model was validated separately against flow structure measurements, solids tracer measurements and experiments with the injection of water and ethanol, respectively, into beds of FCC particles.

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