Estimation of Local Superficial Gas Velocity in Slurry Bubble Columns Using a Triple Electroresistivity Probe

2008 ◽  
Vol 41 (7) ◽  
pp. 578-584 ◽  
Author(s):  
Katsumi Nakao ◽  
Keiji Furumoto ◽  
Fumio Azakami ◽  
Toru Hasuoka ◽  
Tetsuya Imura ◽  
...  
Keyword(s):  
Bubble Columns ◽  
Gas Velocity ◽  
Slurry Bubble Columns ◽  
Superficial Gas Velocity

scholarly journals Effect of Surfactants on Gas Holdup in Shear-Thinning Fluids

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Shaobai Li ◽  
Siyuan Huang ◽  
Jungeng Fan
Keyword(s):  
Experimental Data ◽  
Liquid Phase ◽  
Sodium Dodecyl ◽  
Shear Thinning ◽  
Gas Holdup ◽  
Bubble Columns ◽  
Gas Velocity ◽  
Shear Thinning Fluids ◽  
Liquid Surface Tension ◽  
Superficial Gas Velocity

In this study, the gas holdup of bubble swarms in shear-thinning fluids was experimentally studied at superficial gas velocities ranging from 0.001 to 0.02 m·s−1. Carboxylmethyl cellulose (CMC) solutions of 0.2 wt%, 0.6 wt%, and 1.0 wt% with sodium dodecyl sulfate (SDS) as the surfactant were used as the power-law (liquid phase), and nitrogen was used as the gas phase. Effects of SDS concentration, rheological behavior, and physical properties of the liquid phase and superficial gas velocity on gas holdup were investigated. Results indicated that gas holdup increases with increasing superficial gas velocity and decreasing CMC concentration. Moreover, the addition of SDS in CMC solutions increased gas holdup, and the degree increased with the surfactant concentration. An empirical correlation was proposed for evaluating gas holdup as a function of liquid surface tension, density, effective viscosity, rheological property, superficial gas velocity, and geometric characteristics of bubble columns using the experimental data obtained for the different superficial gas velocities and CMC solution concentrations with different surfactant solutions. These proposed correlations reasonably fitted the experimental data obtained for gas holdup in this system.

scholarly journals Simple correlations for bubble columns and draft tube airlift reactors with dilute alcohol solutions

2009 ◽  
pp. 183-192
Author(s):  
Ivana Sijacki ◽  
Radmilo Colovic ◽  
Milenko Tokic ◽  
Predrag Kojic
Keyword(s):  
Experimental Data ◽  
Draft Tube ◽  
Liquid Velocity ◽  
Bubble Columns ◽  
Gas Velocity ◽  
Empirical Correlations ◽  
Liquid Circulation ◽  
Superficial Gas Velocity ◽  
Good Agreement ◽  
Airlift Reactors

Simple empirical correlations were developed to predict gas holdup, liquid circulation time, downcomer liquid velocity and volumetric mass transfer coefficient in dilute alcohol solutions in bubble columns and draft tube airlift reactors with single orifice sparger. Also, new experiments were conducted with diluted alcohol solutions to n-octanol, expanding the experimental data from C1 up to C8. The proposed empirical correlations include, beside the superficial gas velocity, the alcohol chain length as the only factor to characterize the liquid phase. The suggested correlations have shown good agreement between the calculated and the experimental data.

scholarly journals Effect of Solid Particles on the Gas Hold Up in the Fluidized Bed Columns: Experimental and Mathematical Studies

2021 ◽  
Vol 12 (4) ◽  
pp. 5004-5011
Keyword(s):  
Particle Density ◽  
Tap Water ◽  
Particle Diameter ◽  
Gas Holdup ◽  
Operating Conditions ◽  
Solid Particles ◽  
Bubble Columns ◽  
Solid Concentration ◽  
Gas Velocity ◽  
Superficial Gas Velocity

The present research investigated the effect of solid properties on the gas holdup of the fluidization bed bubble columns (FBCS). All experiments were performed in the constant clear tap water of 80 cm height. The range of solid particle diameters was 0.7 – 2 mm with two different densities of 1075 and 1200 kg/m3, superficial air velocities 4 – 7 cm/s. It was observed that there are proportional relationships between superficial gas velocity and particle diameter with the gas holdup. While an inverse relationship between solid concentration and particle density with the gas holdup. Mathematical and statistical analysis was also used as a powerful way to represent the gas hold up as a function of different operating conditions.

Prediction of the Gas Holdup in Industrial-Scale Bubble Columns and Slurry Bubble Column Reactors Using Back-Propagation Neural Networks

2005 ◽  
Vol 3 (1) ◽  
Author(s):  
Arsam Behkish ◽  
Romain Lemoine ◽  
Laurent Sehabiague ◽  
Rachid Oukaci ◽  
Badie I Morsi
Keyword(s):  
Neural Networks ◽  
Bubble Column ◽  
Back Propagation ◽  
Gas Holdup ◽  
Bubble Columns ◽  
Catalyst Loading ◽  
Gas Bubble ◽  
Gas Velocity ◽  
Bubble Column Reactors ◽  
Superficial Gas Velocity

The total gas holdup and the holdup of large gas bubbles were predicted in bubble column reactors (BCRs) and slurry bubble column rectors (SBCRs) using two Back-Propagation Neural Networks (BPNNs). Over 3880 and 1425 data points for gas holdup and Large gas bubble holdup respectively, covering wide ranges of gas-liquid-solid physical properties, operating variables, reactor geometry, and gas sparger type/size, were employed to develop, train and validate the two neural networks. The developed BPNN for gas holdup has a topology of [14,9-7,1] and was able to predict the trained and untrained data with an average absolute relative error (AARE), standard deviation, and regression coefficient (R2) of 16, 19 and 90%, respectively. The developed BPNN for large gas bubble holdup has a topology of [14,8,1] and was capable of predicting the trained and untrained data with AARE, standard deviation, and R2 of 10, 14 and 93%, respectively. The BPNNs were then used to predict the effects of pressure, superficial gas velocity, temperature and catalyst loading on the total syngas holdup for Low-Temperature Fischer-Tropsch (LTFT) synthesis carried out in a 5 m ID SBCR. The predicted total syngas holdup appeared to increase with increasing reactor pressure, superficial gas velocity and the number of orifices in the gas sparger. The predicted syngas holdup, however, was found to decrease with increasing catalyst loading and reactor temperature. Also, under similar LTFT operating conditions (P = 3 MPa, T = 513 K, CW = 30 and 50 wt%), the total syngas holdup values predicted for H2/CO ratio of 2:1 and cobalt-based catalyst are consistently lower than those obtained for H2/CO ratio of 1:1 and iron oxide catalyst in the superficial gas velocity range from 0.005 to 0.4 m/s. These predictions are in perfect agreement with reported literature trends, which underscore the reliability and validity of the developed BPNNs in predicting the total syngas holdup and the holdup of large gas bubbles in large-scale bubble columns and SBCRs operating under industrial conditions.

scholarly journals Hydrodynamics and Mass Transfer in a Concentric Internal Jet-Loop Airlift Bioreactor Equipped with a Deflector

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4329
Author(s):  
Radek Šulc ◽  
Jan Dymák
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Liquid System ◽  
Gas Holdup ◽  
Gas Velocity ◽  
Liquid Phase Mass Transfer ◽  
Homogenization Time ◽  
Standard Design ◽  
Superficial Gas Velocity

The gas–liquid hydrodynamics and mass transfer were studied in a concentric tube internal jet-loop airlift reactor with a conical bottom. Comparing with a standard design, the gas separator was equipped with an adjustable deflector placed above the riser. The effect of riser superficial gas velocity uSGR on the total gas holdup εGT, homogenization time tH, and overall volumetric liquid-phase mass transfer coefficient kLa was investigated in a laboratory bioreactor, of 300 mm in inner diameter, in a two-phase air–water system and three-phase air–water–PVC–particle system with the volumetric solid fraction of 1% for various deflector clearances. The airlift was operated in the range of riser superficial gas velocity from 0.011 to 0.045 m/s. For the gas–liquid system, when reducing the deflector clearance, the total gas holdup decreased, the homogenization time increased twice compared to the highest deflector clearance tested, and the overall volumetric mass transfer coefficient slightly increased by 10–17%. The presence of a solid phase shortened the homogenization time, especially for lower uSGR and deflector clearance, and reduced the mass transfer coefficient by 15–35%. Compared to the gas–liquid system, the noticeable effect of deflector clearance was found for the kLa coefficient, which was found approx. 20–29% higher for the lowest tested deflector clearance.

The Latest Frontiers of Bubble Columns and Slurry Bubble Columns. Effect of Oil Dispersion on Flow Characteristics in Bubble Column.

2001 ◽  
Vol 27 (4) ◽  
pp. 477-479
Author(s):  
Yoshiyuki Bando ◽  
Makoto Chaya ◽  
Keiji Yasuda ◽  
Yukio Sakurai ◽  
Masaaki Nakamura ◽  
...  
Keyword(s):  
Bubble Column ◽  
Flow Characteristics ◽  
Bubble Columns ◽  
Slurry Bubble Columns
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