Influence of liquid properties on mass transfer coefficients in bubble columns

1988 ◽  
Vol 53 (4) ◽  
pp. 763-770 ◽  
Author(s):  
Kurt Winkler ◽  
František Kaštánek ◽  
Jan Kratochvíl

The gas phase holdup, the specific interfacial area a, and the liquid-side volumetric mass transfer coefficient kLa have been determined for two selected binary systems water-butanol and butanol-2-ethylhexanol in a short bubble column of 150 mm i.d. at gas phase velocities (air) in the range of uG = (0.31-2.52) . 10-2 m s-1. The kLa-uG dependences show characteristic maxima which only partially can be explained by molecular and surface force interactions, induced by the liquid phase. The main parameter, influencing the kLa-values, is a. At small gas velocities some irregularities in the Sauter diameter d32 and in the values of separated kL are observed.

1983 ◽  
Vol 48 (3) ◽  
pp. 703-710
Author(s):  
Milan Rylek ◽  
Karel Svoboda ◽  
Jindřich Zahradník

Absorption rates of CO2 into aqueous solutions of sodium hydroxide were measured in shallow-bed bubble columns with sieve trays as gas distributors. Experiments were carried out in two cylindrical columns (ID 0.15 and 0.30 m) and in a rectangular unit with square cross-section 1 m2. Liquid side mass transfer coefficients (kL) and specific interfacial area (a) were evaluated from experimental data of absorption rates. The effect of bubble-bed dimensions on mass transfer characteristics is discussed and recommendations for scale-up of bubble column reactors are presented.


2019 ◽  
Vol 0 (0) ◽  
Author(s):  
Sahand Nekoeian ◽  
Masoud Aghajani ◽  
Seyed Mehdi Alavi ◽  
Fatemeh Sotoudeh

Abstract Since surfactants have been recognized as the most frequently faced contaminants of bubble column-related processes over time, their impact on the mass transfer operation of these columns has become a demanding research interest for two recent decades. Despite the similarities expressing the overall negative and positive influence of these chemicals on mass transfer coefficients and specific interfacial area, respectively, the discrepancies and, sometimes, paradoxical results are still under debate in the literature. To make a more comprehensive recognition of the mentioned subject, the current paper has tried to pave the path by reviewing all the major methods utilized in related research works. Thereafter, an interpretative argumentative comparison of the main findings of relevant studies has also been proposed, enlightening some of the research gaps which can be the potential candidates for future studies.


Bubble sizes in bubble column affect the bubble induced mixing of phases, interfacial area and transfer processes. Acoustic technique is used to measure bubble size distribution in a rectangular bubble column of cross section 0.2m x 0.02m for air sparged into water and aqueous solutions of ethylene glycol. Five condenser mikes at intermediate distance of 0.05 m measured above the distributor plate were used to find out the variation of bubble size as the bubbles move up. Sauter-mean bubble diameter and specific interfacial area were estimated from bubble size distribution at several superficial air velocity, static bed height, distance above the distributor plate and ethylene glycol concentration. The BSD exhibited mono-modal distribution and indicated non-uniform homogeneous bubbling regime. Sauter-mean bubble diameter is independent of superficial gas velocity, static bed height and concentration of EG, although, the values were higher than that for air-water system. Sauter-mean bubble diameter decreases as the bubbles move up indicating bubble breakup to take place once the bubbles leave the sparger. The value of interfacial area increases as the static bed height decreases and distance above the distributor plate increases. For air-ethylene glycol solution the values of specific interfacial area are about 200% higher than that observed in case of air-water system. The acoustic technique may be used to measure local values of bubble sizes and specific interfacial area.


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