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

Abstract

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.

Liquid drainage in inclined packed beds—Accelerating liquid draining time via column tilt

“…Atta et al [3] and Schubert et al [4] were the first to describe experimentally and numerically the hydrodynamics of inclined trickle beds. Their studies demonstrated the strong correlation between phase segregation in gas-liquid descending flows and vessel tilt angle.…”

Hydrodynamics of gas–liquid cocurrent downflow in floating packed beds

“…Moreover, pulse flow regime properties such as pulse frequency and propagation velocity were found to decrease as compared to conventional vertical trickle beds. Atta et al (2010) conducted, in parallel to Schubert et al (2010a) experimental work, numerical simulations to identify the main causes for stratification in tilted trickle beds. Among the several drag force closures in trickle beds (Wang et al, 2013), use was made of the relative permeability model within an Eulerian computational fluid dynamics framework to capture the physics of local flow and liquid holdup distribution inside the slanted trickle beds.…”

“…In recent years, a great deal of efforts is being directed towards the design of suitable distributors and/or selection of appropriate packings and internals to minimize fluid maldistribution during ship motion (Armstrong et al, 2000;Darredeau, 2001;Duss and Roza, 2014;Fraysse and Werlen, 2002;Haroun et al, 2013;Kalbassi and Zone, 2005). Other research groups have chosen to study the hydrodynamics prevailing inside stationary inclined packed bedsconjectured to be limiting column postures on a ship - (Atta et al, 2010;Bouteldja et al, 2013;Schubert et al, 2010a) or when packed columns are subjected to slow axial vessel rotations (Bieberle et al, 2013;Härting et al, 2015).…”

Applications of tomography in bubble column and trickle bed reactors

“…Therefore, such simulations need to be validated before they can be used to design industrial systems with confidence (Dudukovic, 2010). Tomographic imaging techniques can provide the validation studies required for these CFD models (Atta, Hamidipour, Roy, Nigam, & Larachi, 2010;Atta, Schubert, Nigam, Roy, & Larachi, 2010b;Bazmi, Hashemabadi, & Bayat, 2012;Boyer, Koudil, Chen, & Dudukovic, 2005;Gunjal, Kashid, Ranade, & Chaudhari, 2005;Hamidipour, Chen, & Larachi, 2013;Krepper, Reddy Vanga, Zaruba, Prasser, & Lopez de Bertodano, 2007;Lopes & Quinta-Ferreira, 2010;Lopes, Quinta-ferreira, & Larachi, 2012;Rabha et al, 2013b;Robbins, El-bachir, Gladden, Cant, & von Harbou, 2012). In one of these studies, summarized in Figure 18.10, an EulereEuler computational model was compared with wire mesh sensor measurements of the time-averaged voidage in the bubble column (Krepper et al, 2007).…”