A two-phase Eulerian approach using relative permeability concept for modeling of hydrodynamics in trickle-bed reactors at elevated pressure

Atta, Arnab; Roy, Shantanu; Nigam, K.D.P.

doi:10.1016/j.cherd.2009.06.011

Cited by 18 publications

(8 citation statements)

References 30 publications

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“…However, the prediction of this hydrodynamic phenomenon seems very difficult even with computational fluid dynamics (CFD). Despite there are a large amount of CFD publications on trickle bed study, most of the researches are only concerned with the prediction of pressure drop and liquid holdup, which employs the Eulerian–Eulerian two‐fluid model . As in the framework of the Eulerian model, the two phases are treated mathematically as interpenetrating continua, which means there is no interface between the gas and liquid.…”

Section: Introductionmentioning

confidence: 99%

Hydrodynamic modeling on the external liquid–solid wetting efficiency in a trickling flow reactor

et al. 2012

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A three-region model was proposed, which considers the bed cross section being composed of a stagnant liquid region, a liquid film region, and a rivulet flow region. To estimate the fractions of the three regions, the fraction of film flow was evaluated first, by transforming the complex trickling flow texture into pure liquid film flow. Through the measurements of liquid holdup and pressure drop for the film flow, a relationship between relative permeability and gas saturation was established, and from which the fraction of film flow region was obtained. It shows packing size is most important to the faction of rivulet flow. The external wetting efficiency of the packing was correlated as the sum of two-third power of the liquid film fraction and the rivulet flow fraction, besides, a correlation based on Reynolds and Galileo numbers of the two phases in the form of ce ¼ 4.85Re 0:42 L Ga À0:25 L Re 0:083 G was proposed.

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Section: Introductionmentioning

confidence: 99%

Hydrodynamic modeling on the external liquid–solid wetting efficiency in a trickling flow reactor

et al. 2012

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“…Therefore, this effort is essentially focused on the CFD studies of hydrodynamics in inclined packed beds for two‐phase co‐current downward flow. An established two‐phase Eulerian framework, based on the porous media concept (Atta et al, 2007a,b, 2009) has been employed to examine the flexibility and viability of CFD simulation approach in case of inclined arrangement of packed bed reactors as well as to apprehend the underlying physics behind flow segregation during reactor operation. The model predictions were validated with our own experimental data and information obtained by a non‐invasive technique for multiphase flow visualisation and local measurements, that is, electrical capacitance tomography (ECT).…”

Section: Introductionmentioning

confidence: 99%

Co‐current descending two‐phase flows in inclined packed beds: Experiments versus simulations

et al. 2010

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The effect of inclination angle of a packed bed on its corresponding gas-liquid flow segregation and liquid saturation spatial distribution was measured in co-current descending gas-liquid flows for varying inclinations and fluid velocities, and simulated using a two-phase Eulerian computational fluid dynamics framework (CFD) adapted from trickle-bed vertical configuration and based on the porous media concept. The model predictions were validated with our own experimental data obtained using electrical capacitance tomography. This preliminary attempt to forecast the hydrodynamics in inclined packed bed geometries recommends for the formulation of appropriate drag force closures which should be integrated in the CFD model for improved quantitative estimation.Résumé: Nous analysons l'effet de l'angle d'inclinaison d'un milieu poreux soumisà unécoulement biphasique gaz-liquide de haut en bas. L'analyse s'est attardée en particulier sur l'aptitudeà la ségrégation gaz-liquide et l'évolution de la saturation liquide en fonction de l'angle d'inclinaison et des vitesses de fluides. Une analyse théorique du phénomène de ségrégation y est effectuée par simulation de type mécanique des fluides numérique selon une approche Eulérienne de l'écoulement biphasique dans l'espace poreux du milieu granulaire. Un début de validation des simulations est discuté sur la base de la distribution spatiale des saturations liquides mesurées par tomographieélectriqueà capacitance. Les premières conclusions de ce travail montrent l'inadéquation relative des lois de fermeture sur les forces de frottement telles qu'elles ontété formulées pour lesécoulements biphasiques descendants verticaux; ce qui requiert des efforts futursà développer des lois de frottement plus adaptées aux géométries biphasiques inclinées.

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“…The implementation of relative permeability model in multidimensional CFD models has been attempted in the literature (Atta et al, 2007a, 2010a). The relative permeability model has proved to be well‐balanced between a low level of detail and an adequate ability to capture the major hydrodynamic trends.…”

Section: Closure Methodolgies For Cfd Modelling Of Tbrsmentioning

confidence: 99%

“…pressure drop and liquid holdup) and experimental data from the literature (Specchia and Baldi, 1977; Rao et al, 1983; Szady and Sundaresan, 1991) were conducted under cold‐flow conditions. To test the applicability of the proposed CFD model in high‐pressure TBR scenarios, Atta et al (2010a) evaluated different combinations of relative permeability correlations to predict the pressure drop and liquid holdup. The CFD model predictions were compared with high‐pressure experimental data collected from different sources.…”

Section: Cfd Modelling and Simulation Of Trickle‐bed Reaction Systemsmentioning

confidence: 99%

Modelling and simulation of trickle‐bed reactors using computational fluid dynamics: A state‐of‐the‐art review

2011

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Trickle-bed reactors (TBRs), which accommodate the flow of gas and liquid phases through packed beds of catalysts, host a variety of gas-liquid-solid catalytic reactions, particularly in the petroleum/petrochemical industry. The multiphase flow hydrodynamics in TBRs are complex and directly affect the overall reactor performance in terms of reactant conversion and product yield and selectivity. Non-ideal flow behaviours, such as flow maldistribution, channelling or partial catalyst wetting may significantly reduce the effectiveness of the reactor. However, conventional TBR modelling approaches cannot properly account for these non-ideal behaviours owing to the complex coupling between fluid dynamics and chemical kinetics. Recent advances in the application of computational fluid dynamics (CFD) to three-phase TBR systems have shown promise of achieving a deeper understanding of the interactions between multiphase fluid dynamics and chemical reactions. This study is intended to give a state-of-the-art overview of the progress achieved in the field of CFD simulation of TBRs over the past two decades. The fundamental modelling framework of multiphase flow in TBRs, advances in important constitutive models, and the application of CFD models are discussed in detail. Directions for future research are suggested.RÉSUMÉ Les lits fixes arrosésà co-courant descendant de gaz et de liquide sont le siège d'innombrables processus catalytiques triphasiques, en particulier dans le domaine du raffinage pétrolier et de la pétrochimie. Les caractères polyphasique et non-idéal de leur hydrodynamique ont des répercussions importantes sur la conversion chimique, la productivité et la sélectivité. Ceci se traduit par l'entremise de la maldistribution des fluides, le mouillage partiel du catalyseur ou desécoulements préférentiels qui peuventêtre déterminants en ce qui a traità l'efficacité du réacteur. La mise enéquation rigoureuse de ces non-idéalités et des couplages réaction-hydrodynamique a longtemps résisté aux approches de conceptualisation dites « conventionnelles ». Cette revue de synthèse s'attarde par conséquentà discuter les récentes avancées dans l'utilisation de la mécanique des fluides numérique comme outil «émergent et non-conventionnel » de description quantitative et fine desécoulements et des réactions catalytiques, et de leur interaction au sein de ces réacteurs. Spécifiquement, nous discuterons de la pertinence des différentes approches multi-fluides mises en oeuvre, des relations constitutives développées et de l'utilisation de la mécanique des fluides numérique pour des applications pratiques des lits fixes arrosés. Nous suggérerons en guise d'épilogue de nouvelles directions de recherche dans ce domaine.Mots clés: Lit fixe arrosé, mécanique des fluides numérique, hydrodynamique polyphasique,équations constitutives tive amination, liquid-phase oxidation, etc.). TBRs are also used for the catalytic abatement of aqueous biocidal compounds in *

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A two-phase Eulerian approach using relative permeability concept for modeling of hydrodynamics in trickle-bed reactors at elevated pressure

Cited by 18 publications

References 30 publications

Hydrodynamic modeling on the external liquid–solid wetting efficiency in a trickling flow reactor

Hydrodynamic modeling on the external liquid–solid wetting efficiency in a trickling flow reactor

Co‐current descending two‐phase flows in inclined packed beds: Experiments versus simulations

Modelling and simulation of trickle‐bed reactors using computational fluid dynamics: A state‐of‐the‐art review

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