Drop-interface electrocoalescence under pulsatile electric fields

doi:10.11949/j.issn.0438-1157.20171068

CIESC Journal ›› 2018, Vol. 69 ›› Issue (2): 815-822.DOI: 10.11949/j.issn.0438-1157.20171068

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Drop-interface electrocoalescence under pulsatile electric fields

LI Bin^1,2, REN Ruijuan¹, SUN Zhiqian¹, WANG Zhenbo¹, LI Xiaoyu¹, JIN Youhai¹

1 State Key Laboratory of Heavy Oil, China University of Petroleum(East China), Qingdao 266580, Shandong, China;
2 School of Chemical and Process Engineering, University of Leeds, Leeds LS2 9JT, UK

Received:2017-08-08 Revised:2017-10-20 Online:2018-02-05 Published:2018-02-05
Supported by:
supported by the China Scholarship Council (201606450040), the National Natural Science Foundation of China (21406267), the Natural Science Foundation of Shandong Province (ZR2014BL029), the Fundamental Research Funds for the Central Universities(16CX06014A) and the State Key Laboratory of Heavy Oil Processing (SLKZZ-2017013).

直流脉冲电场下液滴-界面聚并行为

李彬^1,2, 任瑞娟¹, 孙治谦¹, 王振波¹, 李晓宇¹, 金有海¹

1 中国石油大学(华东)重质油国家重点实验室, 山东青岛 266580;
2 利兹大学化学工程学院, 英国利兹 LS2 9JT

通讯作者: 王振波
基金资助:
中国国家公派留学基金项目（201606450040）；国家自然科学基金项目（21406267）；山东省自然科学基金项目（ZR2014BL029）；中央高校基本科研业务费专项资金项目（16CX06014A）；重质油国家重点实验室资助项目（SLKZZ-2017013）。

Abstract

Abstract:

In order to investigate the drop-interface coalescence mechanism under pulsatile electric fields, micro-experiments were conducted on the effect of electrical parameters (electric field intensities, frequencies and waveforms) and physical parameters (surface tension, conductivity, primary droplet size and SiO₂ particles) with deionized water as dispersed phase and sunflower oil as continuous phase. The results show that two mechanisms exist, i.e. complete coalescence and partial coalescence, during drop-interface coalescence. The dominant factor is the competition of pumping and necking process. Partial coalescence is enhanced with increasing field strengths, while it is decreased with increasing frequencies. This is resulted from the strength of electrostatic force and the stability of droplets under pulsatile fields. With increasing surfactant concentrations, secondary droplets increase rapidly. When the concentration is higher than that of the critical micelle, secondary droplets decrease slightly. With increasing conductivities and SiO₂ concentrations, partial coalescence is enhanced first and then decreases. On the other hand, with increasing primary droplet sizes, partial coalescence increases continuously. Among the waveforms utilized in the experiments, constant DC wave has the highest partial coalescence while sawtooth wave has the lowest. The outcome of this work is potentially useful for optimizing the design of compact and efficient oil-water separators.

Key words: pulsatile fields, electrocoalescence, oil-water interface, secondary droplet

摘要：

为了深入探究直流脉冲电场下液滴-界面聚并行为，针对去离子水作为分散相、葵花油作为连续相的体系，分别改变电场参数（电场强度、频率、波形）和物性参数（界面张力、电导率、液滴粒径、固体颗粒）进行显微实验研究，得到了液滴-界面聚并机制及各参数的影响规律。实验结果表明，液滴-界面存在完全聚并和不完全聚并两种机制，决定因素是泵吸和颈缩过程的相互作用。电场强度增大，不完全聚并程度增大，而电场频率的作用则相反，这与电场力大小和液滴稳定程度有关。随表面活性剂浓度增大，二次液滴急剧增大，超过临界胶束浓度后，小幅减小。随电导率和SiO₂浓度增大，不完全聚并程度均先增大后减小，而随液滴粒径增大，不完全聚并程度持续增大。大部分工况下，液滴在直流稳恒电场下不完全聚并程度高于直流脉冲电场。为脉冲静电破乳机理的深入探讨及高效紧凑脉冲电脱盐脱水设备的研发奠定了理论基础。

关键词: 脉冲电场, 静电聚结, 油水界面, 二次液滴

CLC Number:

TE642.1

LI Bin, REN Ruijuan, SUN Zhiqian, WANG Zhenbo, LI Xiaoyu, JIN Youhai. Drop-interface electrocoalescence under pulsatile electric fields[J]. CIESC Journal, 2018, 69(2): 815-822.

李彬, 任瑞娟, 孙治谦, 王振波, 李晓宇, 金有海. 直流脉冲电场下液滴-界面聚并行为[J]. 化工学报, 2018, 69(2): 815-822.

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Drop-interface electrocoalescence under pulsatile electric fields

直流脉冲电场下液滴-界面聚并行为

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[1]	SUN Zhiqian, JIN Youhai, WANG Lei, WANG Zhenbo. Impact of high-frequency pulse electric field parameters on polarization and deformation of water droplet [J]. CIESC Journal, 2012, 63(10): 3112-3118.
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