Influence of Operating Pressure on Gas Holdup and Flow Regime Transition in a Bubble Column

Due to varied flow behavior, the demarcation of hydrodynamic flow regimes is an important task in the design and scale-up of bubble column reactors. This article reviews most hydrodynamic studies performed for flow regime identification in bubble columns. It begins with a brief introduction to various flow regimes. The second section examines experimental methods for measurement of flow regime transition. A few experimental studies are presented in detail, followed by the effect of operating and design conditions on flow regime transition. A table summarizes the reported experimental studies, along with their operating and design conditions and significant conclusions. The next section deals with the current state of transition prediction, and includes purely empirical correlations, semi-empirical models, linear stability theory, and Computational Fluid Dynamics (CFD) based studies.

Download Full-text

The effect of electrolyte concentration on counter-current gas–liquid bubble column fluid dynamics: Gas holdup, flow regime transition and bubble size distributions

Chemical Engineering Research and Design ◽

10.1016/j.cherd.2016.12.012 ◽

2017 ◽

Vol 118 ◽

pp. 170-193 ◽

Cited By ~ 23

Author(s):

Giorgio Besagni ◽

Fabio Inzoli

Keyword(s):

Fluid Dynamics ◽

Flow Regime ◽

Bubble Size ◽

Electrolyte Concentration ◽

Bubble Column ◽

Gas Holdup ◽

Size Distributions ◽

Flow Regime Transition ◽

Liquid Bubble ◽

Counter Current

Download Full-text

Influence of internals on counter-current bubble column hydrodynamics: Holdup, flow regime transition and local flow properties

Chemical Engineering Science ◽

10.1016/j.ces.2016.02.019 ◽

2016 ◽

Vol 145 ◽

pp. 162-180 ◽

Cited By ~ 29

Author(s):

Giorgio Besagni ◽

Fabio Inzoli

Keyword(s):

Flow Regime ◽

Bubble Column ◽

Regime Transition ◽

Flow Properties ◽

Local Flow ◽

Flow Regime Transition ◽

Counter Current

Download Full-text

Effect of Perforated Plate Open Area on Gas Holdup in Rayon Fiber Suspensions

Journal of Fluids Engineering ◽

10.1115/1.1994878 ◽

2005 ◽

Vol 127 (4) ◽

pp. 816-823 ◽

Cited By ~ 8

Author(s):

Xuefeng Su ◽

Theodore J. Heindel

Keyword(s):

Flow Regime ◽

Mass Fraction ◽

Gas Holdup ◽

Fiber Suspensions ◽

Regime Transition ◽

Open Area ◽

Heterogeneous Flow ◽

Flow Regime Transition ◽

Mass Fractions ◽

Rayon Fiber

Three different aeration plates are used to study their effect on gas holdup and flow regime transition in fiber suspensions. The aeration plates differ by their open-area ratios (A=0.57%, 0.99%, and 2.14%), where the hole diameter remains the same while the number of holes increase. Experiments are performed using three different Rayon fiber lengths (L=3, 6, and 12mm) over a range of superficial gas velocities (Ug⩽18cm∕s) and fiber mass fractions (0⩽C⩽1.8%) in a 15.24cm dia semi-batch bubble column. Experimental results show that the aeration plate with A=0.99% produces the highest gas holdup in an air-water system and low fiber mass fraction suspensions, and the plate with A=2.14% yields the lowest gas holdup in these systems. In medium fiber mass fraction suspensions, the plate with A=0.57% produces slightly higher gas holdup values, while the other two plates yield similar results. The effect of the aeration plate open area on gas holdup diminishes at high fiber mass fractions (C⩾1.2%). All aeration plates generate homogeneous, transitional, and heterogeneous flow regimes over the range of superficial gas velocities for air-water and low fiber mass fraction suspensions. However, the aeration plate with A=2.14% enhances the flow regime transition, i.e., the superficial gas velocity at which transitional flow appears is lower. Additionally, the fiber mass fraction at which pure heterogeneous flow is observed is lower when A=2.14%.

Download Full-text