Effect of oil viscosity on the rheology of oil-in-water emulsions with added solids

This paper reports an experimental study on the effect of oil viscosity on the rheology of oil-in-water (o/w) emulsions with added solids. Four oils having a viscosity range of 0.0024 to 306 Pa . s were used. The size ratio of the solids to oil droplets was varied from 2 to 16. The addition of smaller size solids to the emulsions yielded a higher viscosity than that of larger solids at the same solids volume fraction. However, when the solids were sufficiently large such that the emulsions behaved as a continuous phase towards the solids, the viscosity of the emulsion-solids mixtures tended to be independent of the solids size. The critical size ratio of the solids to oil droplets, above which the emulsions behaved as a continuous phase towards the solids, increased with the oil viscosity. The critical size ratio varied between 3 and 10.     

Rheological properties of bitumen in water emulsions with added solids

Experimental work was carried out to investigate the rheological properties of bitumen in water emulsions containing solids of different shape and size. The bitumen volumetric concentration was varied up to 60%, solids free basis, and the solids volume fraction (total volume basis) was varied up to 0.2. Irregular-shaped silica sand (average diameter: 9 and 33 μm) and smooth spherical glass beads (average diameter: 27 and 44 μm) were used as the added solids. In the low shear stress range, shear thinning behavior was observed for bitumen in water emulsions. At high shear stress, the viscosity of the emulsions became fairly independent of the shear stress. The addition of solids to the bitumen emulsions increased the mixture viscosity. The addition of irregular-shaped silica sand gave a higher viscosity than a similar addition of the spherical glass beads. The viscosity of the emulsion/solids mixtures was influenced by the solids size as well; the smaller size particles gave a higher viscosity. The addition of solids to the bitumen emulsions also induced shear thickening (dilatancy) behavior at high solids volume fraction. The degree of the shear thickening increased with the oil concentration.     

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.     

A STUDY OF SILICONE OIL-IN-WATER EMULSIONS

Emulsions of silicone oil-in water were formed using a Brinkmann Polytron homogenizer with Igepal CO-530 as an emulsifier. Silicone viscosities ranged from 10 to 33,000 mPa.s at 25°C. Rheological characteristics and particle size analyses of silicone oil-in-water emulsions were studied. At high volume fraction of the dispersed phase (70%-75%), silicone oil-in-water emulsions were stable. At lower volume fractions (50%-60%), emulsions formed were less stable and the two phases easily separated in a few days. The emulsions formed with high volume fraction silicone oil show highly non-Newtonian behavior (shear thinning). Emulsions made with low viscosity oils had lower viscosities than those made from high viscosity oils. Relative viscosity-concentration data could be correlated by the Frankel and Acrivos Equation. Increasing the emulsifier concentration of 70% oil-in-water emulsions resulted in a decrease in mean droplet size and an increase in emulsion viscosity. Increasing the intensity of agitation also resulted in higher viscosity and smaller droplet size until a critical energy input above which droplet size increased. Emulsification with low shear mixing provides more control in decreasing mean droplet size with time.     

稠油包水乳状液的表观黏度

以渤海SZ36-1稠油、矿化水为工质配制了2组不同液滴直径的W/O型乳状液,研究了温度、含水率、剪切率和液滴直径对乳状液黏度的影响。结果表明,温度对乳状液表观黏度的影响非常明显,而对相对黏度的影响却较小;同时含水率、剪切率和液滴直径也是影响乳状液黏度的重要因素,低含水率下,剪切率、液滴直径对黏度的影响不明显,而当含水率较高时,剪切率、液滴直径的影响非常突出,乳状液呈现出强烈的剪切稀释特性。利用国内外现有的一些黏度模型对实验获得的黏度数据进行了预测分析,发现Brinkman(1952)模型具有较好的预测精度。     

石蜡油w／o／w型多重乳液的制备及其对维生素C的包裹

以多重乳液相对体积为衡量标准,探讨了石蜡油、乳化剂、以及第一相质量分数对石蜡油w／o／w型多重乳液稳定性的影响。结果表明制备石蜡油w／o／w型多重乳液的较佳条件为：第一相中石蜡油和乳化剂Span80质量分数分别为40％和8％,第一相质量分数为65％,乳化剂Tween80质量分数为1％。采用透析-紫外分光光度法研究了该多重乳液对维生素c的包裹能力,结果表明：多重乳液可以有效包裹维生素C,包裹率达98．55％,且能缓慢释放被包裹的维生素C。     

Stabilization of Heavy Oil‐Water Emulsions using a Bio/Chemical Emulsifier Mixture

In this study, the viscosity reduction of heavy oil has been investigated through the formation of oil‐water emulsion using a bio/chemical emulsifier mixture. Four bioemulsifiers from indigenous Rhodococcus ergthropolis and Bacillus licheniformis strains were used to stabilize a highly‐viscous oil‐in‐water emulsion. The Taguchi method with an L₉ orthogonal array design was used to investigate the effect of various control factors on the formation of the oil/water emulsions. An emulsion with lowest viscosity was formed using ACO4 strain. The substantial stability of the oil‐in‐water emulsion allows the heavy oil to be transported practically over long distances or remain stationary for a considerable period of time prior to utilization. As the result of Taguchi analysis, the temperature and concentration of the emulsifier had a significant influence on viscosity reduction of the emulsion.     

Breakup of non-newtonian emulsion jets

The breakup of non-Newtonian emulsion jets into drops was experimentally studied by ejecting both O/W and W/O emulsions vertically downward into stagnant air through nozzles. Breakup lengths of non-Newtonian emulsion jets were found to be almost equivalent to those of Newtonian jets. Experimental breakup data establish that the static surface tension of the oil phase can be used as the surface tension of W/O emulsion jets, whereas the dynamic surface tension of aqueous surfactant solutions is used as that of O/W emulsion jets. Diameters of drops formed from non-Newtonian emulsion jets are in good agreement with the prediction from the stability theory previously developed by the authors. When the rheological index in a power law model is appreciably smaller than unity and the Ohnesorge number is significantly large, however, drop sizes are larger than the prediction because of the profile relaxation in jets. The critical velocity of emulsion jets, either O/W or W/O emulsion, is significantly lower than that of homogeneous Newtonian jets.     

Predicting the Viscosity of Non‐Newtonian Water‐in‐Oil Emulsions Based on the Lederer Model

The accurate prediction of the viscosity of emulsions is highly important for oil well exploitation. Commonly used models for predicting the viscosity of water‐in‐oil (W/O) emulsions composed by two or three factors cannot always fit well the viscosity of W/O emulsions, especially in the case of non‐Newtonian W/O emulsions. An innovative and comprehensive method for predicting the viscosity of such emulsions was developed based on the Lederer, Arrhenius, and Einstein models, using experimental data. Compared with the commonly applied W/O emulsion viscosity models, the proposed method considers more factors, including temperature, volume fraction of water, shear rate, and viscosity of the continuous (oil) and dispersed phase (water). Numerous published data points were collected from the literature to verify the accuracy and reliability of the method. The calculation results prove the high accuracy of the model.     

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.     

Viscous properties of polymer-thickened water-in-oil emulsions

The viscous flow properties of polymer-thickened water-in-oil emulsions were measured using a coaxial cylinder viscometer. The emulsions were prepared using deionized water and polyisobutylene in oil solutions. Three different molecular weight polyisobutylenes (Vistanex MML-140, Vistanex MML-100, and Vistanex MML-80) were studied. The effects of polymer concentration and water (droplet) concentration on the flow properties were determined. The polymer concentration varied from 0 to 3.96% by weight based on the oil phase whereas the water concentration varied from 0 to 80% by volume (based on total emulsion volume). The polymer solutions behaved like non-Newtonian Ellis model fluids. At low water concentrations, the flow curves for emulsions were similar to their suspending medium (polymer solution). At high values of water concentration, emulsions clearly exhibited a yield stress. The yield stress increased with both water and polymer concentrations. The shear stress/shear rate data for the emulsions possessing a yield stress were described adequately by a modified Herschel-Bulkley model. A comparison was also made of the relative viscosities of emulsions having different polymer concentrations. The relative vis-cosities for polymer-thickened emulsions were found to be significantly lower than the corresponding values for emulsions without polymer. The correlation of relative viscosity/ concentration data is discussed. © 1993 John Wiley & Sons, Inc.     

CONCENTRATED VISCOUS CRUDE OIL-IN-WATER EMULSIONS FOR PIPELINE TRANSPORT

The need to utilize viscous crude oils will increase in the next decade. One means to facilitate pumping of heavy crudes in pipelines is to transport them as concentrated oil-in-water emulsions. Stable emulsions could be prepared by alkali treatment with four of seven viscous crudes studied. Surfactants are formed by reaction of natural acids in the crude with alkali. At crude volume fractions of 60%, emulsion apparent viscosity was lowered as much as 10,000 times.

Viscosities of crude emulsions formed by alkali treatment varied with the nature of the crude and with the ratio of base added to the TAN of the crude. Emulsion viscosities and particle diameters reach extrema close to the equivalence point.

The addition of tall oil enhanced the emulsification ability of some of the crudes with alkali treatment, but one crude required non-ionic surfactant to form an emulsion.     

乳状液膜分离富集氟离子的应用研究

乳状液膜在分离富集溶液中的微量物质方面获得广泛的应用,本文研究了其对溶液中氟离子的分离富集效果,确定了制备稳定乳状液膜的条件：乳化剂（T-154）∶膜增强剂（液体石蜡）∶溶剂（煤油）=3∶2∶95（体积比）,内水相为3%的Al2(SO4)3溶液,油内比为1∶0.6;讨论了分离富集条件,包括乳水比、溶液pH值、搅拌速度和富集时间等因素;应用于环境水样中氟离子的测定,加标回收率为96%～103%,相对标准偏差RSD（n=6）为2.0%～4.8%,结果令人满意。指出该方法操作简单、成本低、效率高,可用于分离富集废水中的氟离子。     

Flow behaviour of oil-in-water emulsions

The rheological behaviour of concentrated oil-in-water emulsions has been investigated using the Weissenberg Rheogoniometer. The oil concentration has been varied from 40 to 95 volume percent. The effects of shear rate and oil concentration on the viscosity have been determined. From the rheological data, the maximum attainable oil concentration in the emulsion has been estimated and is introduced as a parameter in the relationship between relative viscosity and oil concentration to account for certain variations in the emulsion characteristics. Empirical equations have been obtained which correlate zero shear rate viscosity and infinite shear viscosity as a function of reduced oil concentration. Comparison has been made between the emulsion viscosity and the solid-liquid suspension viscosity at high dispersed phase concentration. Estimated maximum attainable oil concentration is found to be in close agreement with the actual maximum concentration that could be achieved experimentally.     

高固含量醋酸乙烯-乙烯共聚乳液的研制

介绍了一种固含量在60％左右的醋酸乙烯-乙烯(VAE)共聚乳液的制备方法。讨论了乳化剂、聚乙烯醇、醋酸乙烯、乙烯、引发剂等对乳液合成及其性能的影响，并确定了合适的生产工艺，该工艺生产的产品固含量高、黏度低、柔韧性好，初粘性、快干性和耐水性均较常规产品有显著提高。     

白油W/O/W型多重乳状液的稳定性研究

以多重乳状液相对体积为衡量标准,用显微镜直接观察,探讨了乳化剂的HLB值、质量分数、亲油亲水乳化剂体积比及油水的相比等对白油W/O/W型多重乳状液体系稳定性的影响。结果表明单一乳化剂体系中适宜的制备条件:乳液中乳化剂质量分数为12.2%,V(Span80)/V(Tween80)=7.5;适合多重乳液稳定的油水相比为:第一相体积比为2.5,第二相体积比为0.2。复合乳化剂体系中适宜的制备条件:第一相乳化剂的HLB值为6.5,V(复合乳化剂)/V(Tween80)=27.5,乳液中乳化剂质量分数为9.5%。     

用聚合型乳化剂制备反相乳液的研究

以丙烯酸钠水溶液为水相,煤油为油相,Span80甲基丙烯酸酯(Span80 MA)聚合型乳化剂、Span80和Twen80为复配乳化剂,制备反相乳液。计算聚合型乳化剂(Span80MA)的HLB值,考察了乳化剂浓度、水相体积分数φ及单体浓度对乳液类型及稳定性的影响规律。结果显示:HLB(Span80MA)=4.0;形成稳定的反相乳液理想条件为:Span80MA∶Span80∶Twen80=0.7∶0.5∶0.2;乳化剂浓度为7%;φ=50%;单体浓度为2.0～3.0 mol/L。     

垂直上升管内气体扰动油水两相乳化液流动特性

气体 -油水乳化液的管内流动是原油开采、油气输运以及许多化工领域中经常遇到的工程现象 ,正确认识油水乳化液在气体扰动下的动力特性对圆管内油、气、水多相流的理论建模具有重要的工程应用和学术价值 .本文通过垂直上升管内油气水三相弹状流的实验研究 ,提出了垂直上升弹状流中油水乳化液黏度计算模型 .基于此模型 ,油水乳化液在气体掺入下的流动特性可表现为气体扰动变稠的非牛顿流体特性和气体扰动变稀的非牛顿流体特性 .     

Particle size distributions and viscosity of suspensions undergoing shear-induced coagulation and fragmentation

The dynamic behavior of concentrated suspensions (up to a solids volume fraction of 20%) of non-spherical particles is investigated theoretically by coupling a rheological law to a population balance model accounting for coagulation and fragmentation of the detailed particle size distribution. In these suspensions, the immobilization of matrix liquid renders the viscosity dependent on the particle aggregation state. The effect of initial solids volume concentration and shear rate on the transient behavior of particle size distribution and suspension viscosity is examined. Power law correlations for the equilibrium flow curves of aggregating suspensions are deduced and compared to experimental data. Steady-state or equilibrium particle size distributions are found to be self-preserving with respect to solids volume fraction and shear rate.     

FLOW CHARACTERISTICS OF GAS-OIL-WATER EMULSION IN PIPES

气体 -油水乳化液的管内流动是原油开采、油气输运以及许多化工领域中经常遇到的工程现象 ,正确认识油水乳化液在气体扰动下的动力特性对圆管内油、气、水多相流的理论建模具有重要的工程应用和学术价值 .本文通过垂直上升管内油气水三相弹状流的实验研究 ,提出了垂直上升弹状流中油水乳化液黏度计算模型 .基于此模型 ,油水乳化液在气体掺入下的流动特性可表现为气体扰动变稠的非牛顿流体特性和气体扰动变稀的非牛顿流体特性 .