Behavior of high viscosity oil droplets in oil-water membrane separation and its influencing factors

doi:10.11949/0438-1157.20240088

Abstract

Abstract:

Membrane separation of heavy oil components in oilfield produced wastewater is an important factor affecting membrane pollution, and the complex oil droplet behavior near the membrane surface directly affects the membrane separation effect under different membrane separation conditions. So it is necessary to study the behavior of high viscosity oil droplets near the membrane surface. Based on experimental results of the physical properties of actual oilfield produced wastewater, the dissipative particle dynamics (DPD) method was used to analyze the behavior of oil droplets by combining the trajectory of high viscosity oil droplets and the interaction energy between oil droplets. The results show that the double oil droplets exhibit two types of behaviors: passing and coalescing. Each can be divided into three behavioral stages: liquid drainage between oil droplets, oil droplet contact, and oil droplet stabilization. The decrease of the distance between double oil droplets and the distance between oil droplets and the membrane surface was conducive to the coalescence of oil droplets, which was conducive to oil-water separation, and the decrease of the distance between oil droplets and the membrane surface would cause the position of oil droplets after collision to be further away from the membrane surface. The presence of surfactants hindered the coalescence of oil droplets and was not conducive to oil-water separation, and ionic surfactants had a stronger hindering effect due to their strong repulsion between hydrophilic heads. The presence of the third oil droplet promoted the coalescence of the double oil droplets, and the degree of coalescence promotion was affected by the collision angle of oil droplets. The research results can provide a basis for the subsequent study of the interaction between oil droplets and separation membranes and the effectiveness of oil-water separation, as well as theoretical support for the setting and technical optimization of membrane oil-water separation conditions.

Key words: membrane separation, dissipative particle dynamics, simulation, oil droplet behavior, surfactants

摘要：

膜法分离油田采出废水中的重油组分是膜污染的重要影响因素，且不同膜分离条件下膜面附近的复杂油滴行为直接影响膜分离效果，所以研究膜面附近的高黏度油滴行为十分必要。基于实际油田采出废水物性数据的实验测定结果，采用耗散粒子动力学（DPD）方法结合高黏度油滴轨迹和油滴间相互作用能结果对油滴行为进行细化分析。结果表明，双油滴呈现掠过和聚并两大类行为，又可各分为三个行为阶段：油滴间排液、油滴接触和油滴复稳；双油滴间距和油滴与膜面间距的减小有助于油滴聚并，从而有利于油水分离，且油滴与膜面间距的减小会导致油滴碰撞后的位置更远离膜面；表面活性剂的存在阻碍油滴聚并，不利于油水分离，且离子型表面活性剂因其亲水头间的强排斥力而阻碍作用更强；第3油滴的存在会促进双油滴聚并，有利于油水分离，其促聚并程度受油滴碰撞角的影响。研究结果可为后续的油滴与分离膜相互作用及油水分离效果的研究提供依据，也可为油水膜分离条件的设置和技术优化提供理论支持。

关键词: 膜分离, 耗散粒子动力学, 模拟, 油滴行为, 表面活性剂

CLC Number:

TQ 028.4

Zongwei HUO, Yabin NIU, Yanqiu PAN. Behavior of high viscosity oil droplets in oil-water membrane separation and its influencing factors[J]. CIESC Journal, 2024, 75(6): 2262-2273.

霍宗伟, 牛亚宾, 潘艳秋. 油水膜分离中高黏度油滴行为研究和影响因素分析[J]. 化工学报, 2024, 75(6): 2262-2273.

Figures/Tables 16

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体系分类	自扩散系数/(m²/s)	动力黏度/(mPa·s)	界面张力/(mN/m)
水^[20-21]	2.30×10^-9	0.89	—
油	2.02×10^-11	136.14	—
油-水	—	—	8.9654
油-水-CTAB	—	—	0.2746
油-水-SDS	—	—	0.3261
油-水-SLS	—	—	1.7496
油-水-Tween-80	—	—	7.6272

体系分类	自扩散系数/(m²/s)	动力黏度/(mPa·s)	界面张力/(mN/m)
水^[20-21]	2.30×10^-9	0.89	—
油	2.02×10^-11	136.14	—
油-水	—	—	8.9654
油-水-CTAB	—	—	0.2746
油-水-SDS	—	—	0.3261
油-水-SLS	—	—	1.7496
油-水-Tween-80	—	—	7.6272

名称	DPD无量纲符号	DPD无量纲单位	实际值
质量	m	1	1.14×10^-24kg
长度	r_c、x、z、……	1	1.5066×10^-9m
温度	Θ	1 (k_BT)	298 K
能量	E	1 (k_BT)	4.1164×10^-21J
时间	t	1 (r_c(m/E)^1/2)	25.0266 ps
速度	v	1 (1/(m/E)^1/2)	60.1999 m/s
剪切速率	G	1 (1/t)	0.03996 ps^-1

名称	DPD无量纲符号	DPD无量纲单位	实际值
质量	m	1	1.14×10^-24kg
长度	r_c、x、z、……	1	1.5066×10^-9m
温度	Θ	1 (k_BT)	298 K
能量	E	1 (k_BT)	4.1164×10^-21J
时间	t	1 (r_c(m/E)^1/2)	25.0266 ps
速度	v	1 (1/(m/E)^1/2)	60.1999 m/s
剪切速率	G	1 (1/t)	0.03996 ps^-1

液相类型	N_{m_par}	s	γ	r_c
水相	4	0.25	20	1.0
油相	4	0.25	2650	1.0
油水相间	4	0.25	39.7	1.0