Critical comparison of hydrodynamic models for gas–solid fluidized beds—Part I : bubbling gas–solid fluidized beds operated with a jet

Patil, DJ; Annaland, van M Martin Sint; Kuipers, J.A.M.

doi:10.1016/j.ces.2004.07.059

Cited by 174 publications

(82 citation statements)

References 38 publications

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“…(9), except at distances greater than the static height of the bed surface, y 0.30 m, where the theoretical model is not applicable. This level of similarity between model and simulation for mean bubble diameter profile along the bed height is also observed in other previous publications (see, for instance, Van Wachem et al, 1998;Patil et al, 2005) The experimental data of bubble diameter are inside the simulation data dispersion shown in Fig. 9b.…”

Section: Bubble Diameter and Velocitysupporting

confidence: 89%

“…This is perhaps due to its compromise between computational cost, level of detail provided, and potential of applicability. As a conse quence, there is an increasing need of verification and validation of the closure models utilised in the two fluid simulation of gas fluidized beds in different operative conditions and applications (see, for instance, Peirano et al, 2001;McKeen and Pugsley, 2003;Patil et al, 2005;Taghipour et al, 2005;Li et al, 2009). However, as some authors have pointed out (Grace and Taghipour, 2004), this verification and validation should be interpreted and extra polated with caution due to the complex nature of fluidized beds.…”

Section: Introductionmentioning

confidence: 99%

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Comparison between two-fluid model simulations and particle image analysis & velocimetry (PIV) results for a two-dimensional gas–solid fluidized bed

Hernández-Jiménez

Sánchez-Delgado

Gómez-García

et al. 2011

Chemical Engineering Science

109

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a b s t r a c tThis work compares simulation and experimental results of the hydrodynamics of a two dimensional, bubbling air fluidized bed. The simulation in this study has been conducted using an Eulerian Eulerian two fluid approach based on two different and well known closure models for the gas particle interaction: the drag models due to Gidaspow and Syamlal & O'Brien. The experimental results have been obtained by means of Digital Image Analysis (DIA) and Particle Image Velocimetry (PIV) techniques applied on a real bubbling fluidized bed of 0.005 m thickness to ensure its two dimensional behaviour. Several results have been obtained in this work from both simulation and experiments and mutually compared. Previous studies in literature devoted to the comparison between two fluid models and experiments are usually focused on bubble behaviour (i.e. bubble velocity and diameter) and dense phase distribution. However, the present work examines and compares not only the bubble hydrodynamics and dense phase probability within the bed, but also the time averaged vertical and horizontal component of the dense phase velocity, the air throughflow and the instantaneous interaction between bubbles and dense phase. Besides, quantitative comparison of the time averaged dense phase probability as well as the velocity profiles at various distances from the distributor has been undertaken in this study by means of the definition of a discrepancy factor, which accounts for the quadratic difference between simulation and experiments The resulting comparison shows and acceptable resemblance between simulation and experiments for dense phase probability, and good agreement for bubble diameter and velocity in two dimensional beds, which is in harmony with other previous studies. However, regarding the time averaged velocity of the dense phase, the present study clearly reveals that simulation and experiments only agree qualitatively in the two dimensional bed tested, the vertical component of the simulated dense phase velocity being nearly an order of magnitude larger than the one obtained from the PIV experiments. This discrepancy increases with the height above the distributor of the two dimensional bed, and it is even larger for the horizontal component of the time averaged dense phase velocity. In other words, the results presented in this work indicate that the fine agreement commonly encountered between simulated and real beds on bubble hydrodynamics is not a sufficient condition to ensure that the dense phase velocity obtained with two fluid models is similar to that from experimental measurements on two dimensional beds.

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Section: Bubble Diameter and Velocitysupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Comparison between two-fluid model simulations and particle image analysis & velocimetry (PIV) results for a two-dimensional gas–solid fluidized bed

Hernández-Jiménez

Sánchez-Delgado

Gómez-García

et al. 2011

Chemical Engineering Science

109

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“…However, in the studies aforementioned, there are large memory requirements and long calculation time because each particle is tracked individually. [18][19][20] (3) Eulerian-Eulerian models, where gas phase models and solid phase models are solved in an Eulerian framework. Govind et al 21 used Arastoopour and Gidaspow's 22 early hydrodynamic model to simulate an one-dimensional steadystate entrained-bed pilot-plant gasification system.…”

mentioning

confidence: 99%

Two fluid model using kinetic theory for modeling of one‐step hydrogen production gasifier

Lü

Zhang

et al. 2008

AIChE Journal

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in Wiley InterScience (www.interscience.wiley.com).A Two Fluid Model (TFM) using kinetic theory of granular flow has been developed to describe an innovative process of hydrogen production in a single step. An extended Multi-species of Solid Phase (MSP) method is proposed to simulate the gas-solid heterogeneous reactions in an entrained flow gasifier, as opposed to Single-species of Solid Phase (SSP) in previous studies. The intrinsic equations of methane steam reforming and water-gas shift reactions are used for a good understanding of the reaction mechanism for high concentration of hydrogen production under higher pressure. On the basis of the results of computing, the main feature of core-annular reaction zone is predicted in the fully developed flow region. And the similar flame-like structure for velocity and temperature is observed to emerge from the feed injection zone at the bottom of gasifier. The model well illustrates the effects of CaO on enhancing the concentration of hydrogen and sequestering CO 2 in the process of coal gasification. The advantages of pressure gasification are also shown that coal conversion increases with increasing pressure while H 2 S concentration and tar content decreases. Moreover, there is a steep increase in H 2 S and tar species initiated from the entrance of gasifier and then a decrease at the next section. The model shows good agreement with the measurements of flow field and gas products concentration in laboratory-scale plants.

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“…Closure equations for the solid phase pressure and the solid phase viscosity have to be provided derived from the kinetic theory of granular flow [31]. The kinetic theory of granular flow is an extension of the classical kinetic gas theory realizing for inelastic particle/particle interaction [32,33]. Although these models have been frequently used for bubbling fluidized beds [34], mixing [35], downflow reactors [36] and spouted beds [37], Jung and Gamwo [38] were the first to apply multi-phase CFD modeling for chemical looping combustion processes.…”

Section: Multi-phase Fluid Dynamicsmentioning

confidence: 99%

A Study on the Role of Reaction Modeling in Multi-phase CFD-based Simulations of Chemical Looping Combustion

Kruggel‐Emden

Štěpánek

Munjiza

2011

Oil Gas Sci. Technol. – Rev. IFP Energies nouvelles

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Résumé -Impact du modèle de réaction sur les simulations CFD de la combustion en boucle chimique -La combustion en boucle chimique (Chemical Looping Combustion) est une technologie de combustion efficace permettant le captage in situ du CO 2 pour des charges gazeuses ou solides. Dans l'optique du développement et de l'extrapolation du procédé, la CFD est un outil de simulation à fort potentiel qui s'appuie notamment sur des modèles cinétiques pour décrire les réactions gaz-solide. Ces modèles décrivant les réactions sont généralement assez simples pour limiter les temps de simulation et sont obtenus à partir d'expérimentations en thermobalance. Il y a encore peu de travaux de modélisation CFD du procédé CLC et il est difficile d'estimer l'importance du modèle décrivant les réactions chimiques sur les résultats des simulations. Abstract -A Study on the Role of Reaction Modeling in Multi-phase CFD-based Simulations of Chemical Looping Combustion -Chemical Looping Combustion is an energy efficient combustion technology for the inherent separation of carbon dioxide for both gaseous and solid fuels. For scale up and further development of this process multi-phase CFD-based simulations have a strong potential

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Critical comparison of hydrodynamic models for gas–solid fluidized beds—Part I : bubbling gas–solid fluidized beds operated with a jet

Cited by 174 publications

References 38 publications

Comparison between two-fluid model simulations and particle image analysis & velocimetry (PIV) results for a two-dimensional gas–solid fluidized bed

Comparison between two-fluid model simulations and particle image analysis & velocimetry (PIV) results for a two-dimensional gas–solid fluidized bed

Two fluid model using kinetic theory for modeling of one‐step hydrogen production gasifier

A Study on the Role of Reaction Modeling in Multi-phase CFD-based Simulations of Chemical Looping Combustion

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