Experimental Study of Volumetric Gas-Liquid Mass Transfer Coefficient in Slurry Bubble Columns
Notice bibliographique
Résumé
Slurry bubble column reactors (SBCRs) are extensively employed in a variety of processes in which efficient contact between the gas, liquid, and solid phases are of critical importance.In this context, in the past decade, SBCRs have found numerous applications in chemical, biochemical, and petrochemical industries.Bubble column reactors offer a number of advantages: superior heat and mass transfer rates, low operating and maintenance costs, excellent mixing of solids, uniform temperature distribution, and compactness.It is well established that a comprehensive understanding of the mass transfer phenomena is essential in order to design and scale-up SBCRs for industrial purposes.The fact that the mass transfer rate is connected to a large number of factors including reactor dimensions, operating conditions, physical properties of each phase makes the problem even more complicated.Despite the fact that there are several studies on the impact of solid particles on hydrodynamics and mass transport in SBCRs, still, there is no general agreement regarding the prevailing mechanism or the magnitude of such effect.More importantly, the majority of previous studies utilized laboratory scale test rig to investigate the role of solid particles; thus, the results may not be relevant to large scale reactors mainly due to the differences in hydrodynamics.To address these research gaps, in the present study, a pilot scale slurry bubble column has been used to investigate the volumetric gas-liquid mass transfer coefficient ( ) in two-phase (airwater) and three-phase (air-water-glass beads) systems.The influence of superficial gas velocity, solid particle concentration, and solid particle size on were experimentally explored.The obtained results were justified by taking into account the hydrodynamics, various mass transfer theories applicable to SBCRs.In the last part of the study, a reliable model (i.e.correlation) was developed to estimate the mass transfer coefficient based on the operating conditions, design variables and the properties of the three phases.Regarding the effect of superficial gas velocity in the air-water system, it was observed that increasing the gas velocity (in a wide range of 0.40-21.30cm/s) leads to a higher mass transfer rate.This can be attributed to the better contact between the liquid and gas phase, and the more gas holdup.Interestingly, it was noted that regardless of the gas velocity, the variation in the mass transfer coefficient in the radial direction is not significant, which can be partly ascribed to the high vii liquid phase mixing in the column.It was found that the concentration (0, 1, 3, and 5% v/v) and size (71 and 156 m) of solid particles (i.e.glass beads) strongly affect the behavior of the system and the mass transfer rate.The effect of the solid phase on depends on the gas velocity.In low gas velocities, the presence of solid particles adversely affects the mass transfer, while at high velocities, solids particles are beneficial.Using large size glass beads (i.e.156 m) caused a noticeable improvement in the mass transfer coefficient, mainly due to turbulence increasing in the gas-liquid interface by the particles.The developed correlation for predicting the mass transfer coefficient in two and three-phase systems incorporates Schmidt, Galilei, Froude and Bond numbers, and gas and liquid density, oxygen diffusivity, and column diameter.The developed correlation could reproduce the experimental data successfully: mean absolute percentage error < 4.81% and standard deviation ~ 0.27 %.
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Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,001 | 0,000 |
| Bibliométrie | 0,001 | 0,001 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».