Experimental and computational study of the bed dynamics of semi‐cylindrical gas–solid fluidized bed

Abstract

With computational fluid dynamics (CFD) it is possible to get a detailed view of the flow behaviour of the fluidized beds. A profound and fundamental understanding of bed dynamics such as bed pressure drop, bed expansion ratio, bed fluctuation ratio, and minimum fluidization velocity of homogeneous binary mixtures has been made in a semi-cylindrical fluidized column for gas-solid systems, resulting in a predictive model for fluidized beds. In the present work attempt has been made to study the effect of different system parameters (viz., size and density of the bed materials and initial static bed height) on the bed dynamics. The correlations for the bed expansion and bed fluctuations have been developed on the basis of dimensional analysis using these system parameters. Computational study has also been carried out using a commercial CFD package Fluent (Fluent, Inc.). A multifluid Eulerian model incorporating the kinetic theory for solid particles was applied in order to simulate the gas-solid flow. CFD simulated bed pressure drop has been compared with the experimental bed pressure drops under different conditions for which the results show good agreements.La simulation par ordinateur de la dynamique des fluides (CFD) permet de décrire le comportement desécoulements dans les lits fluidisés. Uné etude fondamentale et approfondie de la dynamique de lit, tels la perte de charge de lit, le taux d'expansion de lit, le taux de fluctuation de lit et la vitesse de fluidisation minimale de mélanges binaires homogènes, aété réalisée dans une colonne fluidisée semi-cylindrique pour des systèmes solides de gaz, permettant d'obtenir un modèle prédictif pour les lits fluidisés. Dans le présent travail, on a tenté d'étudier l'effet de différents paramètres de système (à savoir, la taille et la masse volumique des matériaux de lit et la hauteur statique initiale de lit) sur la dynamique de lit. Des corrélations ontétéétablies pour l'expansion de lit et les fluctuations de lit en s'appuyant sur l'analyse dimensionnelle de ces paramètres de système. Uneétude par ordinateur aégalementété menéeà l'aide du logiciel commercial de CFD Fluent (Fluent, Inc.). Un modèle eulérien multifluide faisant appelà la théorie cinétique pour les particules solides aété utilisé afin de simuler l'écoulement gaz-solides. La perte de charge de lit simulée par la CFD aété comparéeà la perte de charge de lit expérimentale dans différentes conditions et les résultats montrent un bon accord.

Validation of the CFD model for prediction of flow behaviour in fluidized bed reactors

“…A number of works on validation of the model have been published [2][3][4][5][6]. A reasonably good agreement between experimental and computational results is reported.…”

On the Computational Modeling of Unfluidized and Fluidized Bed Dynamics

“…Pressure drop values corresponding to inlet gas velocities below minimum fluidization velocity were very far off from those values measured during the experiments. This phenomenon is one of the facets to be explored herein, and is again mentioned in a study performed by Sahoo et al [9]. The study [9] examined the effects of varying bed material and static bed height.…”

“…This phenomenon is one of the facets to be explored herein, and is again mentioned in a study performed by Sahoo et al [9]. The study [9] examined the effects of varying bed material and static bed height. The particles that were studied had very large diameters (Geldart D).…”

“…1 À e mf (9) 3 Numerical Modeling 3.1 Governing Equations. An Eulerian-Eulerian multiphase flow model is selected in ANSYS FLUENT V R [14] to simulate granular flow in a fluidized bed.…”