Novel gas holdup and regime transition correlation for two-phase bubble columns

G Besagni,F Inzoli

doi:10.1088/1742-6596/923/1/012011

Abstract

The gas holdup is dimensionless parameter of fundamental and practical importance in the operation, design and scale-up of bubble columns. Unfortunately, the many relationships between the bubble column fluid dynamic parameters and the various variables characterizing the system make it difficult to find general correlations for the precise estimation of the gas holdup. Wilkinson et al. (1992), in their pioneering paper, proposed a correlation to predict the gas holdup in industrial-scale bubble columns, based on the physical properties of the phases and the operating conditions. However, this correlation lacks in generality, as it does not take in account the bubble column design. In this paper, we propose a generalization of the Wilkinson et al. (1992) gas holdup correlation to take into also the bubble column design parameters. Starting from considerations concerning the flow regime transition, corrective parameters are included to account for the effects introduced by the gas sparger openings, the bubble column aspect ratio and the bubble column diameter. The proposed correlation has been found to predict fairly well previously published gas holdup and flow regime transition data.

Highlights

Two-phase bubble columns are multiphase reactors where a gas phase is dispersed into a liquid phase in the form of dispersed bubbles or of ―coalescence-induced‖ bubbles
In this paper, we propose a generalization of the Wilkinson et al [2] gas holdup correlation to take in account both the physical properties and the operating conditions, as well as the bubble column design
Starting from considerations concerning the flow regime transition, corrective parameters are included in the gas holdup correlation to account for the effects introduced by the gas sparger openings, the bubble column aspect ratio and the bubble column diameter

Summary

Introduction

Two-phase bubble columns are multiphase reactors where a gas phase is dispersed into a liquid phase in the form of dispersed bubbles or of ―coalescence-induced‖ bubbles. Wilkinson et al [2], in their pioneering paper, proposed a correlation to predict the gas holdup in industrial bubble columns, based on the physical properties of the phases and the operating conditions (i.e., high pressure operation). In this paper, we propose a generalization of the Wilkinson et al [2] gas holdup correlation to take in account both the physical properties and the operating conditions, as well as the bubble column design. Starting from considerations concerning the flow regime transition, corrective parameters are included in the gas holdup correlation to account for the effects introduced by the gas sparger openings, the bubble column aspect ratio and the bubble column diameter. 3. The experimental dataset and methods To calibrate and validate the proposed scheme of correlation, gas holdup and flow regime transition point data are needed. Dc [m] 0.200 0.290 0.162 0.162 0.162 0.160 0.630 0.380 0.150 0.154 0.150 0.160 0.385 0.300 0.330 0.330 0.200 0.380 0.152 0.380 0.380 0.380 0.305 0.200 0.600 0.300 0.300 0.150 0.230 0.385 0.200 0.090 0.102 0.140 do [mm]

Novel correlation: calibration and validation procedures

Correlation validation

Conclusions