Dispersion characteristics of charged bubbles in an electric dispersion tubular packed bed

doi:10.11949/0438-1157.20250005

Abstract

Abstract:

A new gas dispersion method of electric field dispersion technology coupled with tubular packed bed was proposed, and an electric disperser coupled tubular packed bed experimental device was built. Using a biodiesel-nitrogen upward flow system and high-speed imaging, the bubble dispersion process was visualized to investigate the dispersion mechanism of charged bubbles and the dispersion characteristics of bubble groups under a non-uniform electric field. The results indicate that under the influence of the electric field force, bubbles accelerate detachment and disperse into multiple uniformly sized charged bubbles. As the characteristic electric field strength increases, the Sauter mean diameter of the bubble group decreases from 1.80 mm to 650 μm, forming a narrow Gaussian distribution. Based on these findings, the electric disperser was further coupled with the tubular packed bed to examine the effects of characteristic electric field strength, gas flow rate at the orifice, liquid flow rate, and packing type on the secondary dispersion of charged bubble groups before and after passing through the packed bed. The results demonstrate that the initial dispersion by the electric disperser and the secondary dispersion within the packed bed exhibit strong synergy. The number of bubbles per unit volume in the packed bed outlet region remains stable between 4.0×10⁷ and 8.0×10⁷, with the Sauter mean diameter of the bubble group stabilizing between 600—700 μm. Moreover, the electric disperser-coupled tubular packed bed exhibits excellent stability and adaptability under various operating conditions. Without altering the gas-liquid ratio, real-time control of charged bubbles can be achieved by adjusting the characteristic electric field strength. These findings provide a reference for the application and development of electric dispersion coupled with packed bed technology in gas-liquid two-phase reactors.

Key words: bubble, electric dispersion, tubular packed bed, gas-liquid two-phase flow, control

摘要：

本文提出一种电场分散技术耦合管式填充床的新型气体分散方法，搭建了电分散器耦合管式填充床实验装置；并采用生物柴油-氮气上升流体系，通过高速摄像仪，开展气泡分散过程可视化研究，探究非均匀电场作用下荷电气泡的分散机制及其气泡群的分散特性。结果表明：在电场力作用下，气泡加速脱离，分散成多个粒径均一的荷电气泡；随着特征电场强度增加，气泡群的索特平均直径从1.80 mm减小到650 μm，呈现窄峰高斯分布。在此基础上，进一步将电分散器耦合管式填充床，考察特征电场强度、孔口气体流速、液体流速及填料类型对流经填充床前后荷电气泡群的二次分散影响规律。结果表明：电分散器的初始分散与填充床的二次分散具有较好的协同作用，填充床出口区的气泡单位体积数量密度基本稳定在（4.0 × 10⁷）~（8.0 × 10⁷）个/m³，气泡群的索特平均直径能够稳定在600~700 μm；此外，电分散管式填充床在不同工况下均具有良好的稳定性与适用性，在不改变气液比的条件下，通过改变特征电场强度可实现对荷电气泡的实时调控。研究结果为电分散耦合填充床技术在气液两相反应器中的应用与拓展提供了参考。

关键词: 气泡, 电分散, 管式填充床, 气液两相流, 调控

CLC Number:

O 359

Xiaojiang LIANG, Weiwei CHEN, Jianan LUO, Haotian FEI, Xuelei YE, Wenhao LI, Yong NIE. Dispersion characteristics of charged bubbles in an electric dispersion tubular packed bed[J]. CIESC Journal, 2025, 76(8): 3915-3931.

梁晓江, 陈薇薇, 罗佳南, 费浩天, 叶雪蕾, 李文豪, 聂勇. 电分散管式填充床中荷电气泡的分散特性研究[J]. 化工学报, 2025, 76(8): 3915-3931.

Figures/Tables 23

Table 1 Physical properties of biodiesel and nitrogen （25℃）

材料

密度/

(kg/m³)

相对介电常数

表面张力/

(N/m)

动力黏度/(mPa∙s)

电导率/

(S/m)

Table 2 Physical properties of packing

填料

材料

比表面积/

(m²/m³)

Fig.1 Diagram of electric dispersion tubular packed bed device

Fig.2 Steps of image processing: (a) original image; (b) binarization; (c) fill the holes; (d) screen bubbles

Fig.3 Schematic diagram of electric force for bubbles under non-uniform electric field

Fig.4 Bubble evolution sequence diagrams at varying electric field strength in an electro-disperser (uL=0.033 m/s, uG=1.062 m/s）

Fig.5 Force analysis diagram of a bubble under the action of an electric field[31]

Fig.6 Picture of the charged bubble cluster at the outlet of the electric dispersion and particle size distribution (uL=0.033 m/s, uG=1.062 m/s)

Fig.7 Charged microbubble population characteristics before entering the packing material (uL=0.033 m/s, uG=1.062 m/s)

Fig.8 Comparison of gas dispersion characteristics of electric dispersion empty tube device and electric dispersion tubular packed bed at different electric field strength (uL=0.033 m/s, uG=1.062 m/s)

Fig.9 Comparison of gas dispersion characteristics of electric dispersion empty tubular packed bed and electric dispersion tubular packed bed at different electric field strength (uL=0.033 m/s, uG=1.062 m/s)

Fig.10 Particle size distribution of charged bubble cluster before and after packing under three characteristic with and photographs with electric field strengths (uL=0.033 m/s, uG=1.062 m/s)

Fig.11 Characteristic changes of charged microbubble populations before and after packing at various electric field strength (uL=0.033 m/s, uG=1.062 m/s）

Fig.12 Plot of gas dispersion characteristics of electric dispersion tubular packed bed with different characteristic electric field strengths (uL=0.033 m/s, uG=1.062 m/s)

Fig.13 Particle size distribution of charged bubble cluster before and after packing at three liquid flow rates and photographed (E=7.58 × 103 kV/m, uG=1.062 m/s)

Fig.14 Characteristics of charged microbubble populations before and after packing at three liquid velocities (uG=1.062 m/s, E=7.58 × 103 kV/m)

Fig.15 Plot of gas dispersion characteristics of electric dispersion tubular packed bed at three liquid flow rates (uG=1.062 m/s, E=7.58 × 103 kV/m)

Fig.16 Particle size distribution of charged bubble groups before and after packing at three gas flow rates and photographed (E=7.58 × 103 kV/m, uL=0.033 m/s)

Fig.17 Characteristics of charged microbubble populations before and after packing at three gas velocities (uL=0.033 m/s,E=7.58 × 103 kV/m)

Fig.18 Plot of gas dispersion characteristics of electric dispersion tubular packed bed for three orifice gas flow rates (uL=0.033 m/s, E=7.58 × 103 kV/m)

Fig.19 Particle size distribution of charged bubbles before and after passing through the three kinds of fillers and photographed images (uG=1.062 m/s, uL=0.033 m/s, E=7.58 × 103 kV/m)

Fig.20 Characteristics of charged microbubble populations before and after three kinds of packings (uG=1.062 m/s, uL=0.033 m/s, E=7.58 × 103 kV/m)

Fig.21 Plot of the overall gas dispersion characteristics of electric dispersion tubular packed bed with three types filler (uG=1.062 m/s, uL=0.033 m/s, E=7.58 × 103 kV/m)

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