We present a comprehensive literature review on the two-phase bubble column; in this review we deeply analyze the flow regimes, the flow regime transitions, the local and global fluid dynamics parameters, and the mass transfer phenomena. First, we discuss the flow regimes, the flow regime transitions, the local and global fluid dynamics parameters, and the mass transfer. We also discuss how the operating parameters (i.e., pressure, temperature, and gas and liquid flow rates), the operating modes (i.e., the co-current, the counter-current and the batch modes), the liquid and gas phase properties, and the design parameters (i.e., gas sparger design, column diameter and aspect ratio) influence the flow regime transitions and the fluid dynamics parameters. Secondly, we present the experimental techniques for studying the global and local fluid dynamic properties. Finally, we present the modeling approaches to study the global and local bubble column fluid dynamics, and we outline the major issues to be solved in future studies.

Two-Phase Bubble Columns: A Comprehensive Review

The effect of liquid phase properties on bubble column fluid dynamics: Gas holdup, flow regime transition, bubble size distributions and shapes, interfacial areas and foaming phenomena

Hydrodynamics and mass transfer characteristics in an internal loop airlift reactor with different spargers

We experimentally investigate the effect of ethanol (0.05% in mass) on the hydrodynamics of a large-diameter and large-scale bubble column. The bubble column is 5.3 m in height, has an inner diameter of 0.24 m, and we consider gas superficial velocities in the range of 0.004–0.20 m/s. The experimental investigation consists of gas holdup measurements and image analysis. The gas holdup measurements are used to investigate the flow regime transition and the global bubble column hydrodynamics. The image analysis is used to investigate the bubble shapes and size distributions near the sparger and in the developed region of the column. The presence of ethanol increases the gas holdup, stabilizes the homogeneous regime and modifies the bubble shapes and size distributions. In particular, the addition of ethanol increases the mean bubble aspect ratio and decreases the bubble diameters. The results suggest that the addition of ethanol changes the bubble properties, which modifies the bubble size distribution and shapes, thus, stabilizing the homogeneous flow regime and, finally, increasing the gas holdup.

Experimental investigation on the influence of ethanol on bubble column hydrodynamics

The influences of aliphatic alcohols (CnH2n+1OH, n = 1–4) and their concentrations (0–1 vol.-%) on gas holdup, liquid circulation velocity, mixing time, and overall volumetric gas-liquid oxygen mass transfer coefficient were considered in a split-cylinder airlift reactor sparged with air. The carbon chain length of the alcohols and their concentration affect the airlift reactor performance. Alcohols reduced the average bubble sizes and increased the gas holdup, the interfacial area for mass transfer, and the gas-liquid mass transfer coefficient. Since butanol has the most carbon atoms in its chain, it had the most significant effect on gas holdup and mass transfer enhancement. It also decreased the liquid circulation velocity by surface tension reduction. Two correlations based on dimensionless groups were applied to investigate the effect of hydrodynamics and molecules on gas holdup and mass transfer. A satisfactory agreement between correlation and experimental results was observed.

Gas-Liquid Hydrodynamics and Mass Transfer in Aqueous Alcohol Solutions in a Split-Cylinder Airlift Reactor

The aim of this work was to investigate an influence of different alcohols on the behavior of a draft tube airlift reactor. The main hydrodynamic and mass transfer parameters in 1 wt % aqueous solutions of five aliphatic alcohols were examined. The results showed that alcohol addition enhanced gas holdup and mass transfer coefficient, but led to notable reduction of liquid velocity and hence elongation of circulation time, relative to the values determined for water. By introducing the surface tension gradient as a relevant independent variable, we defined a simple empirical correlation for overall gas holdup, circulation time, and mass transfer coefficient. The proposed empirical correlations have shown a satisfactory agreement between the calculated and the experimental data. © 2007 American Institute of Chemical Engineers AIChE J, 2007

V. Havran

Papers

Hydrodynamics and mass transfer in a draft tube airlift reactor with dilute alcohol solutions