Gas/liquid interfacial area per unit volume and volumetric mass transfer coefficient in stirred slurry reactors

1987 ◽  
Vol 10 (1) ◽  
pp. 204-215 ◽  
Author(s):  
Michael Schmitz ◽  
Artur Steiff ◽  
Paul-Michael Weinspach
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Unit Volume ◽  
Interfacial Area ◽  
Volumetric Mass Transfer Coefficient ◽  
Slurry Reactors

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.

Relation between Volumetric Mass Transfer Coefficient and Power Input per Unit Volume for Converging-Diverging Tube Airlift Fermenter

2010 ◽  
Vol 8 (1) ◽  
Author(s):  
Tapan K Ghosh ◽  
Bimal C Bhattacharyya
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Unit Volume ◽  
Hydrodynamic Characteristic ◽  
Power Input ◽  
Volumetric Mass Transfer Coefficient ◽  
External Loop ◽  
Airlift Fermenter ◽  
Uniform Tube

A conventional external loop uniform tube airlift fermenter (UT-ALF) was modified to improve its performance. The riser part was replaced by a converging- diverging tube. The newly developed reactor system is named a converging-diverging tube airlift fermenter (CDT–ALF). The modified bioreactor (CDT–ALF) provides a unique hydrodynamic characteristic. Empirical correlation was developed to determine KLa with respect to power input per unit volume. The modified system (CDT-ALF) shows 250% higher KLa compared to conventional one.

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.

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.

scholarly journals Ultrasonic Investigation of Hydrodynamics and Mass Transfer in a Gas-Liquid(-Liquid) Stirred Vessel

2005 ◽  
Vol 3 (1) ◽  
Author(s):  
A.H.G. Cents ◽  
D.W.F. Brilman ◽  
G.F. Versteeg
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Water System ◽  
Interfacial Area ◽  
Volumetric Mass Transfer Coefficient ◽  
Volume Fractions ◽  
Liquid Mass ◽  
Liquid Mass Transfer ◽  
Transfer Parameters

The rate of gas-liquid mass transfer is very important in several industrial chemical engineering applications. In many multi-phase reaction systems, however, the mechanism of mass transfer is not well understood. This is for instance the case in Gas-Liquid-Solid (G-L-S) and Gas-Liquid-Liquid (G-L-L) systems. To obtain more knowledge of the mechanism of mass transfer, the mass transfer coefficient, kL, and the interfacial area, a, should be studied separately. In this work an ultrasonic measurement technique is used to study the local interfacial area in a standard sized vessel, equipped with a Rushton type impeller. This is done in combination with experimental determination of the volumetric mass transfer coefficient, kLa, using the dynamic oxygen method, to obtain values for kL. The gas hold-up is determined additionally to obtain values for the Sauter mean bubble diameter at different positions in the vessel. In a coalescing air-water system the bubble size was non-uniform throughout the vessel and increased from small bubbles at the impeller along with the flow pattern to larger sizes in the bulk of the vessel. In a non-coalescing electrolyte system the vessel was much more uniform and the bubbles were smaller when compared to the air-water system. To obtain overall values of the mass transfer parameters the local values were integrated according to their volume fraction in the reactor. In both coalescing and non-coalescing systems the overall values for the mass transfer parameters were in good agreement with literature correlations. The addition of small volume-fractions of toluene to an air-water system caused a strong decrease in both the volumetric mass transfer coefficient and in the gas hold-up. The interfacial area increased, however, but it was shown that this was due to the presence of microbubbles in the solution, which do not take part in the mass transfer process. The enhancing effect on gas-liquid mass transfer due to the addition of larger volume-fractions of toluene could be described reasonably well by a homogeneous model of the shuttle mechanism.

Sign in / Sign up

Export Citation Format

Share Document