Experimental Study of Volumetric Gas-Liquid Mass Transfer Coefficient in Slurry Bubble Columns
Bibliographic record
Abstract
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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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".