scholarly journals Gas Hold-Up and Mass Transfer in a Vessel with an Unsteady Rotating Concave Blade Impeller

Energies ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 346
Author(s):  
Sebastian Frankiewicz ◽  
Szymon Woziwodzki
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Interfacial Area ◽  
Transfer Efficiency ◽  
Volumetric Mass Transfer Coefficient ◽  
Mass Transfer Efficiency ◽  
Liquid Systems ◽  
The Creation

The steady mixing of gas-liquid systems is used where a large development of the interfacial area is required. However, the presence of gas in the liquid reduces the efficiency of mass transfer by reducing the mixing power, due to the creation of gas formations behind the impeller blades and the reduction in density. The efficiency of mass transfer can be increased by using a concave blade impeller or unsteady mixing. Mass transfer efficiency studies for these impellers and unsteady mixing are limited. This paper presents an analysis of the influence of the impeller construction on the gas hold-up and volumetric mass transfer coefficient kLa. Impellers with a different number of concave blades, and with alternatively arranged concave blades, were analyzed. The obtained results were compared with the standard flat blade turbine. The obtained results indicate that the arrangement of the concave blades has the greatest effect on reducing the gas hold-up and kLa. Higher values were obtained for the four-bladed and six-bladed impellers. A comparison of the gas hold-up rate for the unsteady and steady mixing has shown that for steady mixing greater gas hold-up is achieved. The volumetric mass transfer coefficient for unsteady mixing is also greater compared to steady mixing, indicating greater efficiency in mass transfer.

Influence of Particles and Electrolyte on Gas Hold-Up and Mass Transfer in a Slurry Bubble Column

2006 ◽  
Vol 4 (1) ◽  
Author(s):  
Keshav C Ruthiya ◽  
John van der Schaaf ◽  
Ben F.M. Kuster ◽  
Jaap C Schouten
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Bubble Column ◽  
Bubble Diameter ◽  
Interfacial Area ◽  
Large Bubble ◽  
Volumetric Mass Transfer Coefficient ◽  
Gas Velocity ◽  
Slurry Concentration

In this paper, the influence of carbon and silica particle slurry concentration up to 20 g/l (4 vol%) on regime transition, gas hold-up, and volumetric mass transfer coefficient is studied in a 2-dimensional slurry bubble column. From high speed video image analysis, the average large bubble diameter, the frequency of occurrence of large bubbles, the gas-liquid interfacial area, and the large bubble hold-up are obtained. The liquid side mass transfer coefficient is calculated from the volumetric mass transfer coefficient and the gas-liquid interfacial area. The lyophilic silica particles are rendered lyophobic by a methylation process to study the influence of particle wettability. The influence of organic electrolyte (sodium gluconate) and the combination of electrolyte and particles is also studied. It is found that lyophilic silica, lyophobic silica, and lyophobic carbon particles at concentrations larger than 2 g/l (0.4 vol%) decrease the gas hold-up and shift the regime transition point (where the first large bubbles appear) to a lower gas velocity. The volumetric mass transfer coefficient increases with gas velocity, increases with electrolyte concentration, decreases with slurry concentration, and is higher for lyophobic particles. The liquid side mass transfer coefficient increases with gas velocity, bubble diameter, and is higher for lyophobic particles. A correlation for the mass transfer coefficient based on dimensionless numbers is proposed for the heterogeneous regime.

Experimental and Computational Studies of Aerated Stirred Tank with Dual Impeller

2020 ◽  
Vol 18 (3) ◽  
Author(s):  
Shivanand M. Teli ◽  
Viraj S. Pawar ◽  
Channamallikarjun Mathpati
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Large Scale ◽  
Interfacial Area ◽  
Gas Velocity ◽  
Stirred Tanks ◽  
Mixing Performance ◽  
Liquid Systems ◽  
Superficial Gas Velocity

AbstractStirred tanks are commonly used in chemical and allied industries for reaction and separation. In order to improve the mixing performance, large scale reactors are often equipped with multiple impellers. In the case of gas-liquid systems, the gas hold-up, mass transfer coefficient, and interfacial area strongly depend on the size and type of impellers, clearance between impellers and superficial gas velocity. In the present work, the effect of the impeller speed, superficial gas velocity, and top impeller position has been investigated on gas hold-up, interfacial area, and mass transfer coefficient. Computational fluid dynamics have been carried out for the multiphase multi-impeller system and the model predictions have been compared with the experimental data.

Enhancement of Gas Physical Absorption in Gas-Liquid-Liquid System

2011 ◽  
Vol 201-203 ◽  
pp. 2870-2874
Author(s):  
Wen Xiu Li ◽  
Guang Rong Xu ◽  
Zhi Gang Zhang ◽  
Zhi Ling Ji
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Organic Phase ◽  
Amplification Factor ◽  
Bubble Diameter ◽  
Interfacial Area ◽  
Volumetric Mass Transfer Coefficient ◽  
Absorption Increase ◽  
Physical Absorption

The enhancement of physical absorption of CO2 in the presence of second liquid phase (dispersed organic phase) was investigated due to many important industrial applications. Gas-liquid interfacial area, volumetric mass transfer coefficient and amplification factor were calculated and discussed using penetration model. The experimental results indicated that addition of the dispersed organic phase to water leads to the increase of volumetric mass transfer coefficient by 46%, 34%, 20% for heptanol, toluene and heptane respectively. The performed in this paper shows that addition of the dispersed organic phase to water increases gas-liquid interfacial area and reduces bubble diameter. These two effects play an essential role in the rate of carbon dioxide absorption increase. The effect of enhancement could be quantified by an amplification factor.

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