重质油包水乳液破乳过程及降黏强化机制

重质油包水（W/O）乳液普遍存在于石油开采与加工过程中,因其高黏度、高密度、强界面稳定特性,导致重质油包水乳液分离困难,生产成本增加。为了提高重质W/O乳液的分离效率,本文探究了温度与甲苯加入量对重质油黏度的影响规律。在此基础上,研究了上述降黏过程与脱水率之间的协同机制。采用自制的TJU-3破乳剂对重质W/O乳液进行破乳,通过调整破乳剂在乳液中的浓度和破乳温度得到了最佳工艺条件。利用分子模拟的方法构建了重质油平均分子模型并计算了SARA四组分在不同甲苯含量的重质油中的扩散系数,分析了甲苯添加量对重质油中SARA四组分相互作用的影响规律,研究了沥青质分子和TJU-3破乳剂分子在油水界面的运移过程。结果表明：重质油的黏度降低到1500mPa·s时,可实现在1h内完全破乳;黏度降低到50mPa·s时可实现在20min内完全破乳。当破乳剂在乳液中的浓度为400mg/L时,乳液的脱水率最高;破乳温度为60℃时,破乳速度最快。SARA四组分中胶质的扩散系数增大最显著,是重质油的黏度能被甲苯迅速降低的主要原因。TJU-3分子能够破坏沥青质界面膜,进而实现破乳。该协同机制和工艺条件可为石油工业中重质W/O乳液的低温快速破乳工艺提供参考。     

Functions of Demulsifiers in the Petroleum Industry

There are an increasing number of crude oil fields that are now producing both crude oil and water emulsions; such fields are both onshore and offshore. These emulsions are formed during oil exploitation due to the presence of natural surfactants, such as asphaltenes and resins. These molecules strongly stabilize the water/oil interface and prevent coalescence of water droplets. As water/oil phase separation is necessary before oil transportation and refining, demulsifiers are used to break water-in-oil emulsions. This review presents the crude oil emulsion formation, factors affecting demulsification of crude oil emulsion such as demulsifier chemical structure, water content, partition coefficient (K_P), and demulsifier concentration. This review also covers the kinetics and mechanism of the demulsification process.     

沥青质和胶质对辽河稠油乳状液破乳的影响

针对辽河曙光稠油乳状液粘度大、破乳难、破乳温度高等问题,以曙光稠油为研究对象,从中分离出沥青质和胶质,用傅里叶变换红外光谱法分析其主要官能团,考察沥青质和胶质对稠油乳状液粘度及破乳效果的影响。测定了不同含量胶质、沥青质对稠油油／水界面张力的影响。结果证实,沥青质比胶质含有羟基多,分子间氢键作用强烈,更容易造成原油粘稠。随着叫（胶质）、训（沥青质）升高,稠油乳状液脱水率降低,w（沥青质）超过2．1％,或w（胶质）超过32％时,稠油乳状液的破乳十分困难。w（胶质）、w（沥青质）的增高会使破乳剂水溶液与原油的界面张力增大,w（沥青质）增加0．7％比叫（胶质）增加7％原油的界面张力升高还要大,所以训（沥青质）的增加对油水界面张力影响更大。     

Stabilization of liquid water-in-oil emulsions by modifying the interfacial interaction of glycerol monooleate with aqueous phase ingredients

Glycerol monooleate (GMO)-stabilized liquid water-in-vegetable oil emulsions are difficult to stabilize due to the desorption of GMO from the water-vegetable oil interface toward the oil phase. This work improved the stability of GMO-stabilized liquid 20 wt% water-in-canola oil (W/CO) emulsion by modifying the dispersed aqueous phase composition with hydrogen bond-forming agents. As a control, 20 wt% water-in-mineral oil (W/MO) emulsion was also utilized. Different concentrations of hydrogen bond-forming agents (citric acid (CA), ascorbic acid (AA), low methoxyl pectin (LMP)) with and without salts (sodium chloride (S) or calcium chloride (Ca)) were added to the aqueous phase before emulsification, which enhanced emulsifier binding to the water–oil interface. W/CO emulsion without any aqueous phase additive destabilized instantly, whereas W/MO emulsion stayed stable during the week-long observation. The addition of hydrogen bond-forming agents and salts significantly improved emulsion stability. LMP, with many hydrogen bond-forming groups, was able to provide the highest emulsion stability after 7 days in both oils compared to AA, CA and their mixtures with S. Emulsions with both oils formed weak gels due to the formation of an extensive network of water droplet aggregates. Overall, the hydrogen bond-forming agents interacted with GMO at the interface, thereby favoring their presence at the water droplet surface and significantly improving the stability of liquid W/CO emulsions. The knowledge developed in this research can be useful in utilizing GMO to stabilize liquid water-in-oil emulsions without using any fat crystal network.     

Development of a Continuous Electric Coalescer of W/O Emulsions in Liquid Surfactant Membrane Process

Abstract

The development of an efficient, continuous demulsification apparatus is needed in the industrial separation process utilizing the liquid surfactant membrane technique. A test apparatus for continuous demulsification was constructed in which a pulsed dc high potential is applied to W/O emulsions flowing between parallel copper electrodes of a perforated plate. Efficient demulsification was achieved by an operation in which the demulsified oil phase was absent between the emulsion and the upper electrode. When the feed rate of emulsion was adjusted to be equal to the demulsification rate, the latter value was proportional to the square root of the applied potential and independent of the distance between the electrodes.     

pH值对原油乳状液稳定性的影响

研究了pH值对原油乳状液稳定性的影响, 测定了胶质和沥青质在油水界面上的聚集和铺张情况, 不同pH值下油水界面张力以及胶质和沥青质模拟乳状液的稳定性变化, 并且完成了不同pH值下的乳状液化学破乳以及电场破乳实验。沥青质相对胶质更易在界面上聚集和铺展, 形成高黏弹性的界面膜。pH值为酸性或碱性时都能有效降低油水界面张力, 增加乳状液稳定性, 使其化学破乳脱水困难, 而破乳实验也验证了这一观点。随着pH值从2增加到10, 胶质模拟乳状液和沥青质模拟乳状液稳定性变化大, 变化趋势则刚好相反, 胶质模拟乳状液稳定性增加, 油水分离速度减慢;沥青质模拟乳状液稳定性减弱, 体系电导率0.21～1.8mS/cm。因此pH<7时, 沥青质稳定能力强, 而胶质稳定能力弱, 电脱水过程中电脱装置正常工作;pH>7时, 结果相反, 表明电脱装置短路现象与沥青质、胶质稳定能力变化相关。     

无机盐对新疆油田二元驱过程中乳状液影响研究

乳状液稳定性对于化学驱提高原油采收率具有非常重要的作用,稳定性过强会导致采出液破乳困难;稳定性过弱,乳状液会很快破乳,使复合驱油体系波及体积受到影响。系统研究了不同类型无机盐对新疆油田二元复合驱油体系乳状液稳定性的影响。结果表明,无机盐可以加速水包油型乳状液的破乳,特别是二价阳离子,能将破乳率提高1倍以上;阴离子的种类对乳状液的稳定性影响较弱。无机盐对乳状液破乳效率的影响与离子价态和Zeta电位有关。     

冷冻解冻法破除液体石蜡W/O乳状液

冷冻解冻法是一种新型的破除W/O乳状液的物理破乳方法.为了揭示冷冻解冻破乳作用机制,本文以稳定性好的液体石蜡W/O乳状液为研究对象,采用差热扫描量热仪（DSC）与显微镜,研究了高黏度连续相液体石蜡体系的W/O乳状液的冷冻解冻破乳过程.结果表明：该破乳过程是一个渐进过程.当乳珠粒径均匀细小,小于5.5 μm时,乳珠在冷冻解冻循环中逐渐长大,经多次冷冻解冻后完成破乳;然而当乳珠粒径较大时,如51 μm,乳状液体系仅需单次冷冻解冻循环就可破乳较完全,破乳率超过90%.此外,乳状液含水量的增加有利于提高破乳效率.乳状液水相的凝固点受乳珠尺度的影响,但受含水量的影响不显著.当乳珠粒径较大时,水相凝固点随乳珠粒径的减小而降低;但是当乳珠粒径降至5.5 μm时,乳珠粒径的改变对其影响已不明显.     

Mass transfer studies on multiple emulsion as a controlled mass release system

A novel type of multiple emulsions which contain a microemulsion in macrodroplets, was prepared by a two-step emulsification procedure. Mineral oil was used as the oil phase with a mixture of Aerosol OT and Span 20 as primary emulsifiers. A water-in-oil microemulsion was prepared by gradual addition of water in oil containing both these emulsifiers. This microemulsion system, when dispersed in an aqueous solution containing secondary emulsifier, produces water-in-oil-in-water (W/O/W) multiple emulsions. The release rate of solute dissolved in the internal aqueous phase was measured using the dialysis technique. A theoretical model describing the diffusion of a multiple emulsion system was developed, which predicts the half-life for 50% of the internal solute to diffuse to the external phase. Experimental results showed the stability of multiple emulsions improved significantly upon using a thermodynamically stable microemulsion as a primary emulsion and a polymeric surfactant as a secondary emulsifier. As a resull, half-life of these multiple emulsions is greater than that of conventional multiple emulsions.     

Robust graphene/poly(vinyl alcohol) aerogel for high-flux and high-purity separation of water-in-oil emulsion and its computational fluid dynamic simulation

Due to the trade-off between purity and flux, the development of high-purity, high-flux oil–water separation materials is still an arduous challenge. Herein, to achieve emulsion separation with high purity and high permeability, fluorinated graphene/poly(vinyl alcohol) aerogel (FGPA) with strong honeycomb was obtained via a facile freeze-drying method, and the separation mechanism was investigated via computational fluid dynamics (CFDs) simulation. The as-prepared FGPA exhibited superhydrophobicity-superoleophobicity and cyclic compression stability. Under the complex pore and superhydrophobicity, FGPA could separate water-in-oil emulsions with droplet sizes several times smaller than their own aperture only under gravity with ultrahigh flux (3255 L m⁻² h⁻¹) and ultrahigh purity (99.9%). Also, the separation process as visualized using simulations revealed that the vortex accelerates the demulsification behavior and promotes the gathering of water droplets rebounding on the superhydrophobic surface, so that the water droplets are intercepted. Therefore, FGPA has broad practical application potential in high-flux and high-purity oil–water emulsion separation.     

Nonionic surfactants from poly(ethylene terephthalate) waste: II. Effect of temperature,salinity, pH-value,and solvents on the demulsification efficiency

The effect of temperature, NaCl concentration (salinity), pH-value, and solvents on the demulsification efficiency of the demulsifiers synthesized from poly(ethylene terephthalate) waste [polyoxyethylenated glycolized product of PET (POGP)] in breaking synthetic water-in-benzene emulsions stabilized by petroleum asphaltenes have been investigated. The demulsification efficiency of the studied polymeric surfactants was found to increase as the temperature was raised and the salinity of the aqueous phase decreased. Neutral pH-value of the aqueous phase of the emulsion was found to be the optimum value causing maximum demulsification efficiency. Water and 1, 2 propylene glycol were found to be the best solvents for the prepared demulsifiers offering maximum demulsification efficacy.     

玉米油W1/O/W2型多重乳状液稳定性的研究

高脂食品严重危害着人类健康,这引起人们对低脂食品的的不断追求,因此脂肪替代品的开发越来越受到人们重视。本试验以玉米油和生物高聚物为主要原料通过两步乳化法制备W1/O/W2多重乳状液作为脂肪替代品(FS),以离心稳定性为衡量标准,用显微镜直接观察,探讨了初复乳乳化工艺、各相相对体积比对玉米油W1/O/W2型多重乳状液体系稳定性的影响。结果表明:1.影响玉米油多重乳状液稳定性的主要因素有:复乳的乳化工艺,内水相与油相体积之比等。2.两步乳化工艺中第二步乳化工艺对复乳稳定性影响较大,其规律是随着乳化强度的提高,粒径减小,稳定性呈上升趋势,适宜的乳化条件为7200 r.min.1,13 min,而第一步乳化工艺对复乳稳定性几乎没有影响。3.内水相与油相、初乳与外水相均是影响复乳稳定性的主要因素,前者主要是依靠改变初乳黏度来影响复乳稳定性,后者主要是乳滴间范德华力与电排斥力共同作用的结果,适宜的体积比分别为1:4和1:1。     

Rapid Salt‐Assisted Microwave Demulsification of Oil‐Rich Emulsion Obtained by Aqueous Enzymatic Extraction of Peanut Seeds

Aqueous enzymatic extraction (AEE) is an environmentally friendly edible‐oil‐extraction process that can also provide edible protein. However, the AEE process may form a stable emulsion in most cases, which seriously limits the large‐scale industry applications for producing vegetable oils. In this study, the salt‐assisted microwave radiation demulsification of the oil‐rich emulsion prepared with AEE from peanuts is investigated. The microwave demulsification method is compared with other conventional demulsification methods, including heating, and freezing–thawing. The salt‐assisted microwave demulsification of the emulsions shows a greater free oil yield than conventional heating demulsification. Moreover, the microwave demulsification shows a similar free oil yield in less time than freezing–thawing method. Under the optimal operating conditions of demulsification, the free oil yield can reach 92.3% with CaCl₂‐assisted microwave demulsification for only 2 min. In addition, the oxidative properties and the fatty acid compositions of the demulsified peanut oil are investigated. No significant difference in the fatty acid composition is observed among salt‐assisted microwave, freezing–thawing, and heating demulsified oil. The oxidative properties of the salt‐assisted microwave demulsified peanut oil is better than the conventional heating demulsified oil. Thus, salt‐assisted microwave demulsification provides a quick and effective demulsification method to obtain vegetable oils with high quality. Practical Applications: Aqueous enzymatic extraction (AEE) is an environmentally friendly edible‐oil‐extraction process. To solve the problem of stable emulsion formed during AEE process, the salt‐assisted microwave demulsification of the oil‐rich emulsion prepared with AEE is developed with high efficiency (demulsification for 2 min). In addition, the oxidative properties of the microwave demulsified oil is better than the conventional heating demulsified oil.     

Erdöl-Emulsionen — Eigenschaften,Stabilität und Spaltung

Petroleum emulsions — Properties, stability, and demulsification . Petroleum always occurs together with brine and is often recovered as an water-in-oil emulsion. Emulsions containing more than 90 percent of water are known; they are often very stable. The viscosity of the emulsions rises at a faster rate than the water content and is always significantly higher than that calculated according to the Einstein equation. Petroleum emulsions are stabilized by adsorption of the asphaltenes and petroleum resins colloidally dispersed in the petroleum. These components form mechanically stable films at the water/oil interface. The films contain several anionic, cationic, and amphoteric interfacially active substances, which are associated to form micelles, and which are adsorbed at the oil/water interface as a result of their interfacial activity. The adsorption films are wetted by the oil phase. The emulsions are stable towards coalescence, but not towards flocculation. Demulsifying agents displace the stabilizers from the interface or change their wettability.     

双重刺激响应型pickering乳液研究进展

Pickering乳液因其极强的稳定性、良好的生物相容性和对环境友好等特点在众多领域有着广泛应用.虽然乳液必须具有良好的稳定性,但实际应用中通过适当的触发机制使其能够实现快速破乳也是非常重要的.响应型Pickering乳液由于在特定因素刺激下可以轻易实现可逆乳化-破乳成为近些年研究的热点.早期研究学者主要研究单一刺激因...     

Stability of high internal phase emulsions with sole cationic surfactant and its tailoring morphology of porous polymers based on the emulsions

Stable w/o high internal phase emulsion (HIPE) using cetyltrimethylammonium bromide (CTAB) as the sole surfactant was prepared with long time further mixing of the emulsion after the addition of aqueous phase was completed, although it was generally considered the emulsion would be unstable according to Bancroft rule. The delta backscattering data of these emulsions showed that the further mixing enhanced the stability of the HIPE significantly, because a dram partial of monomers was initiated in the period of preparing the emulsion, which reduced the diffusion of CTAB from the oil phase to aqueous phase and increased the viscosity of the continuous phase. In addition, the morphology of polyHIPEs based on this type HIPEs was tailored. Increasing aqueous phase fraction resulted in the increase of pore volume which could be up to 24.0 ml/g. Increasing the polymerization temperature led to an increase in average void and interconnect diameter in the resulting porous materials. Additionally, the presence of additives, PEG and ethanol, in the aqueous phase was found to increase the average void diameter remarkably. The interconnect diameter of the materials could be controlled at constant pore volume by tuning PEG and ethanol concentration in the aqueous phase. It was suggested that coalescence was the dominant effect in determining the morphology of the polyHIPEs prepared in the presence of PEG, and Ostwald ripening was the major role in tailoring the morphology of the porous materials with ethanol.     

低压脉冲电场对高浓度O/W型乳化液破乳特性的影响

为实现高含油浓度O/W型乳化液的电场破乳预分水,借鉴电絮凝技术的工作原理自行设计了静态序批式电场破乳预分水实验装置。在对乳化液理化特性进行量化表征以确保其稳定性的基础上,以预分水率为主要评价指标,系统实验研究了电场形式、峰值电压、脉冲频率、占空比及含水率对O/W型乳化液静态破乳预分水特性的影响。结果发现,脉冲直流方波电场下乳化液的破乳效果比直流电场较好;含水率降低使乳化液的破乳程度减弱;峰值电压、脉冲频率和占空比都存在一个最优值。当施加脉冲直流方波电场、电压幅值为40V、脉冲频率为2kHz、占空比为0.5、加电时间为30min时,含水率90%乳化液的预分水率达87.18%。基于实验过程中的现象推测,高含油浓度O/W乳化液的破乳预分水机理包括双电子层作用和类似电絮凝作用。     

RHEOLOGICAL PROPERTIES OF EMULSIONS OF OIL IN AQUEOUS NON-NEWTONIAN POLYMERIC MEDIA

The viscous flow behaviour of emulsions of oil in non-Newtonian Ellis model fluids (aqueous solutions of sodium carboxymethyl cellulose) has been studied experimentally. The addition of oil droplets to a non-Newtonian aqueous suspending media leads to an increase in the apparent viscosity of the emulsion system. The shape of the emulsion flow curves (apparent viscosity versus shear-stress plots) is found to be similar to that of the suspending media; consequently, the emulsion flow curves at various oil concentrations (0 to 70% by volume) are described adequately by the Ellis model. The relative viscosities of the emulsions of oil in non-Newtonian aqueous suspending media are significantly lower than those exhibited by emulsions of oil in Newtonian media.     

Effect of oil type on stability of high internal phase water-in-oil emulsions with super-cooled internal phase

This study considered the stability and rheology of a type of high internal phase water-in-oil emulsions (W/O) emulsion. The aqueous phase of the emulsions is a super-cooled inorganic salt solution. The oil phase is a mixture of industrial grade oils and stabilizer. Instability of these systems manifests as crystallization of the metastable dispersed droplets with time. This work focused on the effects of oil polarity and oil viscosity on the stability of these emulsions. Ten types of industrial oils, covering the viscosity range 1.4–53.2?cP, and with varying polarity, were used in combination with polymeric poly(isobutylene) succinic anhydride (PIBSA) and sorbitan monooleate (SMO)-based surfactants. The effect of oil relative polarity on rheological parameters of the emulsion was evident mainly in the emulsions stabilized using polymeric surfactant, whereas the oil viscosity did not show any significant effect. The optimum stability of the emulsions stabilized with SMO was achieved using high polar oils with a viscosity of 3?±?0.5?cP. However, when using the PIBSA surfactant, the best emulsion stability was achieved with low polar, high viscosity oils.     

油水乳状液的稳定机理及其化学破乳技术的研究进展

油/水乳状液的破乳是重油生产和加工过程的重要环节,破乳剂的研发一直是油田化学中重要的研究内容。本文综述了国内外化学破乳剂研发的现状与趋势,阐述了重油中以沥青质为主的天然乳化剂的结构特点,深入分析了沥青质在油水乳状液的形成与稳定的过程中所起到的关键性作用,揭示了油水乳状液的形成与稳定性机理。进一步论述了具有普适性强、无毒、可生物降解且价格低廉的天然高分子破乳剂的破乳作用及其最新研究结果。重点介绍了微吸液管技术和原子力显微镜技术等现代分析手段在油水乳状液破乳过程中对相关微观机理研究的重要应用。