含聚结构件油水分离器性能研究

由沉降和聚结机理可知选取适当的聚结构件可增加油水乳状液的粒径,加快沉降速度,从而提高分离器性能.今设计了一种含聚结构件的分离器,在长为1800 mm,内径为384 mm的重力式分离器内安装入口构件和聚结板,通过测量不同流速和工况条件下四种聚结板对油水乳状液的粒径质量分离效率,研究分离器性能.结果表明,倒T型入口构件可有效减少分离器流场中的回流和二次涡流,还引入了重力消能和水洗作用.聚结板可显著提高油水分离效率,在流量较大的时候,聚结板分离效果下降,出现对粒径选择性的单一分离作用.聚结板的结构和材质对液滴的聚结沉降影响很大,应根据工况和处理条件进行合理选择.     

Influence of soybean protein isolates-phosphatidycholine interaction on the stability on oil-in-water emulsions

Soybean protein isolates and phospholipids present specific surface properties with synergistic or antagonistic effects on emulsion stability. Oil-in-water emulsions (25∶75 w/w) were prepared using native and denatured soybean isolates (NSI and DSI, respectively) with the addition of phosphatidylcholine (PC) (protein/PC ratio 100∶1 to 10∶1). The effect of ionic strength was also studied by adding sodium chloride (0–100 mM) to the aqueous phase. Analysis of NSI/PC and DSI/PC emulsions showed that the creaming rate diminished upon addition of PC, with the creamed phase showing more stability than those of the control systems. In DSI/PC systems, the coalescence process was partially controlled, as evidenced by a decrease in the size of oil droplets. Both systems were altered by the presence of sodium chloride, with an increase in the creaming rate attributable to flocculation and the coalescence of droplets. Under these conditions, DSI/PC emulsions exhibited a stronger protein-phospholipid interaction than those of NSI/PC.     

Influence of Processing on the Physical Stability of Multiple Emulsions Containing a Green Solvent

The influence of the emulsification process on the microstructure and physical stability of model water‐in‐oil‐in‐water (W/O/W) emulsions formulated with a green solvent and a mixture of amphiphilic copolymers as emulsifiers was investigated. Emulsions were prepared by applying a homogenization step with a rotor‐stator device followed by high‐pressure homogenization. Viscous flow tests, transmitted light optical microscopy, globule size distribution (GSD), and multiple light scattering (MLS) measurements were carried out. The GSDs obtained were the result of a recoalescence due to overprocessing and the coalescence of inner droplets with the outer water phase. MLS detected a main destabilization mechanism by creaming. The passing of the emulsion through a high‐pressure homogenizer (HPH) significantly delayed the creaming process.     

利用受限空间装置从低浓度水包油乳状液中分离油相的研究(英文)

A miniature process for separating the oil phase from dilute oil/water emulsion is developed.This process applies a confined space apparatus,which is a thin flow channel made of two parallel plastic plates.The space between the two plates is rather narrow to improve the collisions between oil droplets and the plate surface.Oil droplets have an affinity for the plate surface and thus are captured,and then coalesce onto the surface.The droplet size distribution of the residual emulsion resulted from the separation process is remarkably changed.The oil layer on the plate weakens the further separation of oil droplets from the emulsion.Three types of plate materials,polypropylene(PP),polytetrafluoroethylene(PTFE) and nylon 66,were used.It is found that PP is the best in terms of the oil separation efficiency and nylon 66 is the poorest.The interaction between droplets in the emulsion and plate surface is indicated by the spreading coefficient of oil droplet on the plate in aqueous environment,and the influences of formed oil layer and plate material on the separation efficiency are discussed.     

Flocculation and Separation of Oil Droplets in Ultrasonic Standing Wave Field

A new method for breaking oil in water emulsion based on flocculation of droplets in high intensity ultrasonic standing wave field was developed in this study and the effect of initial droplets size, type of disperse phase as well as the time of sonication and the height of emulsion in the chamber on the extent of interdroplet interactions were investigated. The results showed that type of disperse phase affects the efficiency of separation process through controlling the initial size of droplets. For the two types of disperse phase in question the efficiency of separation was calculated to be 42.7% for canola oil/water emulsion and 37% for sunflower oil/water emulsion. The time of sonication was found to have a positive contribution to the percent of flocculation and coalescence, so that the largest aggregates were formed after 30 minutes treatment. Also, the optimum height of emulsion in the treatment chamber was determined to be λ/4 at which the strongest flocculation and highest percent of coalescence took place. Increasing the height of emulsion did not significantly influence the course of aggregation and separation.     

聚结技术及其乳化油水分离性能

聚结分离是一种利用油、水两相对材料浸润性的不同而实现乳化液滴聚结长大并最终通过重力沉降实现油水分离的物理方法,这种方法结构可控性好、分离效率高、运行成本低,是乳化油水分离领域的研究热点。本文首先对聚结分离方法进行详细阐述,介绍了聚结分离原理和影响因素;总结了近年来国内外学者对聚结材料表面改性和修饰等方面的研究。通过调控聚结材料的表面具有特殊浸润性,可显著提高油水分离效率;系统介绍聚结分离器的分类及其应用。最后阐述了聚结分离技术在石油化工领域的应用。本文对聚结分离技术进行展望,指出可以进一步研究实际液滴聚结过程和分离效果影响因素,应深入研究分离器在乳化油水分离过程中液滴聚结行为、机理、控制机制将是研究的重点。     

Prediction of average droplet size in flowing immiscible polymer blends

The paper is focused on calculation of the average droplet size in immiscible blends during their steady flow. Available theoretical and experimental results of studies of the droplet breakup and coalescence are utilized to derive the equations describing dynamic equilibrium between the droplet breakup and coalescence. New expression for the coalescence efficiency, reliably reflecting recent theoretical results, is proposed. The equation for the average steady droplet size, controlled by the stepwise breakup mechanism and coalescence of droplets with not very different sizes, is derived for blends containing up to 10–20 vol % of the droplets. For blends with above approximate 20 vol % of the droplets, the breakup by the Tomotika mechanism and coalescence in highly polydisperse system is modeled. Results of the derived equations are compared with experimental data; qualitative agreement is found for the dependence of the droplet size on the amount of the dispersed phase. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45250.     

Numerical optimization and experimental investigation of the aerodynamic performance of a three-stage gas-solid separator

The present research investigates and optimizes the aerodynamic performance of a newly designed compact size three stage mobile gas-solid separator. This separator is designed to collect solid particles with different characteristics at a minimum pressure drop. The minimum particle diameter to be completely collected is 1 μm at solid loading 20 g/m³. The first stage of the separator is a settling chamber which is designed to collect coarse particles (particles down to particle diameter 100 μm). The second stage is a cyclone separator where medium to fine particles (particles down to particle diameter 15 μm) are to be collected. Particles escaping the cyclone separator are collected in the third stage which is a bag filter.A separator conceptual aerodynamic design is first performed to obtain overall separator dimensions. CFD simulation is used in order to optimize the separator aerodynamic performance and reduce the separator size. The separator is then constructed and experimentally investigated. Comparison between CFD results at design point and measured separator total pressure drop shows good agreement.     

聚碳酸酯液液分离器的流体力学模拟和中试试验

对聚碳酸酯混合液,通过液液间歇沉降实验得到分散相液滴的Sauter平均粒径为330 μm。采用Mixture多相流模型对聚碳酸酯液液静态分离器进行了模拟和分析。对平行板、波纹板和斜板进行了比较,得出斜板更适合聚碳酸酯液液分离。考察了斜板长、板间距、倾斜角度、入口流量对液液分离效果的影响,得出对于水油相体积比为0.6的物料,最优的聚结板参数为斜板倾角20°、板长0.8 m、板间距40 mm、筒内最大流速5.3×10^-3 m·s^-1。设计了聚碳酸酯液液分离器,进行了中试试验,水油两相出口浓度接近各自的溶解度值,筒内最大流速为3.9×10^-3 m·s^-1,结果表明该分离器起到了很好的液液分离效果,可以取代原有的碟片离心机设备,降低了设备和操作费用。     

Coalescence behaviour of water droplets in water‐oil interface under pulsatile electric fields

In this research, the deformation of water droplets in sunflower oil-interface under pulsatile electric field was studied experimentally. Three types of coalescence were observed:(i) complete coalescence, (ii) incomplete coalescence and (iii) no-coalescence. The first type is desirable because of leaving no secondary droplets. The second type that produced secondary droplets which caused by necking process, due to extreme elongation of droplets (mostly small droplets), was undesirable; because the small droplets were more difficult to coalesce and remove. The no-coalescence was caused by very fast coalescence and extensive pushing of droplet into the continuous phase. In this work the process was operated with the utilization of a batch cylindrical separator with high voltage system. The lower part of the cylinder was filled with the aqueous phase and its top part was filled with sunflower oil to form an interface between the two phases. The effects of electric field strength, frequency, and waveform types were investigated. It was found that, the ramp-ac waveform was the best waveform, avoiding the production of secondary droplets and in this case the frequency also played an important role.     

Effect of Ionic Strength on Freeze–Thaw Stability of Glycosylated Soy Protein Emulsion

This study used Soy Protein Isolate (SPI), Soy Protein Isolate Hydrolysates (SPH) and Dextran (D) as raw materials. Covalent compounds were prepared by grafting soy protein isolate and soy protein isolate hydrolysate with dextran by water-heating method, which were SPI-D and SPH-D, respectively. The effect of ionic strength (0–500 mM) on the freeze–thaw stability of SPI, SPI-D, and SPH-D emulsions was investigated. Fourier transform infrared analysis and Fluorescence emission spectroscopy analysis indicated that the structure of the protein changed. In this study, it was found that with the increase of ionic strength, the zeta potential of the three samples presented a downward trend and the surface hydrophobicity first decreased and then increased. The addition of ions effectively improved the freeze–thaw stability of the emulsions. The particle size of the emulsions changed little after freeze–thaw cycles, and coalescence degree, creaming index, and oiling off significantly decreased. Especially when the ionic strength reached 300 mM, the degree of coalescence was 248.46%, 170.92%, and 167.77%, respectively, and the oiling off was also reduced by 68.52%, 68.25%, and 59.92%, respectively. The creaming index of the SPI emulsion was 48.49% lower than the creaming index without ions. However, when the ionic strength exceeded 300 mM, the coalescence degree, creaming index, and oiling off of the emulsions increased. Optical microstructures also found that at ionic strength of 300 mM, the oil droplets produced by the three kinds of emulsion after freeze–thaw were smaller than those without ions.     

Effect of particle morphology on the emulsion stability and mechanical performance of polyolefin modified asphalts

Recent federal regulations concenrning roadbed performance have motivated research in polymer modified asphalt binders. Earlier studies on these binders have shown that many of them are susceptible to gross phase separation when the binder is stored at high temperatures under quiescent conditions. This phase separation, in turn, is affected by the initial morphology and storage conditions. In this effort we investigate the effect of particle morphology on the high-temperature emulsion stability of a low-density polyethylene-modified asphalt binder, as well as the concomitant effects on the mechanical behavior. We show for unstabilized emulsions that the dominant phase separation mechanism shifts from coalescence to creaming at a critical particle radius of 4 μm at 110°C. However, stabilized emulsions showed no evidence of gross phase separation for up to 48 hours at 110°C. Dramatically different morphologies were observed for the unstabilized and stabilized emulsions; unstabilized emulsions having teardrop shaped particles and stabilized emulsions having both spherical particles and long cylindrical domains. The mechanical behavior, including the high-temperature dynamic viscoelastic behavior and low-temperature fracture toughness, increased with polyolefin content, but was insensitive to the particle morphology.     

Vergleich des Koaleszenzverhaltens ruhender und umströmter Wasser‐in‐Öl‐in‐Wasser‐Einzeltropfen

Phase inversion of a water‐in‐oil emulsion to a water‐in‐oil‐in‐water double emulsion is practically used for liquid/liquid separation. For successful separation in the water leg the coalescence of the internal droplets with the surrounding continuous water phase is decisive. The determination of this coalescence phenomenon is applied for the process design. Therefore, single water‐in‐oil‐in‐water drops are investigated under static and dynamic conditions by means of high speed imaging. The influence of physical and geometrical parameters on the coalescence time and partial coalescence is determined.     

Numerical simulation of effect of inlet configuration on square cyclone separator performance

This paper presents a numerical study of the gas-solid flow in square cyclone separators with three types of inlet configuration. Three-dimensional Reynolds Stress Model (RSM) was used to simulate the turbulent flow of gas phase and a Lagrangian equation was used to simulate the particle motion. The resulting velocity, separation efficiency and pressure drops were verified by comparison with measured data. The effect of inlet configurations on the turbulent dynamics in the cyclone and the separation efficiency and pressure drop was analyzed. Results showed that inlet configurations influenced the turbulent dynamics in the cyclone and led to different pressure drop and separation efficiency. The separator with double declining inlets (DDI) had the minimum pressure drop and similar efficiency to the separator with double normal inlets (DNI). The separator with single normal inlet (SNI) had the best separation efficiency and the maximum pressure drop. When a baffle was installed in the inlet of separator SNI, the pressure drop increased by about 191% and 34% for the separator with a straight (SNI-1) and curved (SNI-2) baffle respectively on the basis of the pressure drop of separator SNI. The cut and critical diameter of particles were 2 μm and 14 μm for separator SNI-1 and 4 μm and 14 μm for separator SNI-2, while they were 8 μm and 30 μm for separator SNI at the same inlet conditions.     

Neue proteinstabilisierte O/W-Emulsionen

New Protein Stabilized O/W-Emulsions The formation and stabilization of o/w-emulsions were investigated with faba bean globulin isolate and the corresponding acetylated derivative as model substances in dependence on concentration at constant pH-value and on pH-value at constant concentration as well. A centrifugal equilibrium method was developed and the protein distribution in the phases after centrifugation was determined. Optimal conditions (concentration, pH-value and preparation of emulsion) lead to a coating of the oil droplets with protein being stable against coalescence. It is possible to separate those coating droplets in a form of stabile concentrate of emulsion. The acetylated derivative is a more efficient emulsifier and stabilizer than the unmodified faba bean globulin is. For oil droplet size distribution and comparable stability less protein is needed in the case of acetylated derivative. At the same time a stronger interaction between the aqueous phase of the emulsion and the coated oil droplets was found. This is reflected by the existence of a mechanical barrier against the separation of this aqueous phase. The results fo the coalescence stable concentrates of emulsion are the reason to search for a new principle producing o/w-emulsions.     

De-emulsification of 2-ethyl-1-hexanol/water emulsion using oil-wet narrow channel combined with low-speed rotation

Low-speed rotation of disc in an internal circulation of a novel de-emulsification with rotation-dise horizental contactor (RHC-D) realized de-emulsification for O/W emulsions due to repeated coalescence in oil-wet narrow channels at a low rotation speed. For three emulsions included ethanol/water/2-ethyl-1-hexanol, ethanol/water/2-ethyl-1-hexanol/SDS (Sodium Dodecyl Sulfonate) and 2-ethyl-1-hexanol/water/SDS emulsion, deemulsification ratios of oil phase could reach 1, 1 and 0.67 respectively at 170 r·min^-1, and de-emulsification ratios increased obviously after agitating 10 min. De-emulsification experiment in the seam indicated that oil droplet sizes in O/W emulsion became larger after de-emulsification. The main de-emulsification mechanism in RHCD was the coalescence of oil droplets in oil-wet narrow channels. With increase of the rotation speed, oil droplets dispersed better in the aqueous phase. However, de-emulsification effect enhanced due to the increase of the coalescence rate at a bit higher rotation speed. In addition, internal circulation made those O/W emulsions to be broken repeatedly, consequently de-emulsification ratio increased. Repeated de-emulsification through internal circulation might make continuous extraction of ethanol come true at a low rotation speed.     

Precipitation of nanoparticles in submicron emulsions induced by droplet coalescence

The precipitation of BaSO₄ is an in literature thoroughly discussed precipitation reaction. Here the precipitation of BaSO₄ by applying a miniemulsion technique is introduced. This technique involves the preparation of two stable water-in-oil submicron sized emulsions (miniemulsions) via high pressure homogenisation. N-decane presents hereby the continuous phase. The dispersed phases are water based BaCl₂- and K₂SO₄-solutions. Each emulsion contains one of the reactants within the water droplets. After blending the two precursor miniemulsions, the mixture is high pressure homogenised again. During high pressure homogenisation droplets coalesce which induces the formation of nanoparticles by precipitation. The high pressure homogenisation process is chosen in order to allow for controlled droplet-droplet coalescence. Parameters influencing droplet coalescence and particle synthesis such as the homogenisation pressure, the dispersed phase fraction and the precursor concentration are presented.     

The experimental observation and modelling of microdroplet formation within a plastic microcapillary array

This paper reports an experimental study of the formation of a two-phase liquid mixture in a circular capillary tube of 0.74 mm diameter. Organic liquid, the continuous phase, flowed through the capillary. Aqueous liquid, the dispersed phase, was injected through a hypodermic entering the side of the capillary and a stream of aqueous droplets was formed in the flowing organic liquid. The observed droplet diameters depended strongly on the ratio of the flow-rates between the dispersed and continuous phases: droplet diameters ranged between 480 and 64 μm. A simple model gave good predictions, matching the data and showing how the droplet diameter is dependant on the flow rates of the two phases. The flow geometry was similar to the T-junction configuration used for emulsion formation in microfluidic devices and was fabricated from an extruded plastic capillary array termed a microcapillary film (MCF).     

微通道内气泡和液滴自组织行为的研究进展

微流体技术良好的可控性为制备高通量的单分散性气泡或液滴提供了新的途径，气泡和液滴的流动行为因在材料领域具有较大的应用前景而受到关注。综述了近年来微通道内气泡和液滴自组织行为的研究进展。气泡或液滴自组织晶格具有周期性的流动特征，自组织行为受分散相体积分数、液滴或气泡尺寸、聚并效应和通道构型的影响。展望了气泡和液滴自组织行为研究过程中待解决的关键科学问题，为进一步的模拟和实验研究提供了参考。     

卧式重力沉降器油水空间分布研究

为了探究卧式重力沉降器内油水空间的分布规律,通过室内实验方法,全面测量卧式重力沉降器内空间浓度分布,得到空间浓度分布规律,建立回归方程。回归方程定量描述了卧式重力沉降器内部的含油浓度空间分布,便于对内部聚结部件处分散油滴迁移规律进行研究,对设计最佳水相出口也起到一定的指导作用。研究表明:斜板和平板区域聚结作用显著,斜板聚结区域相对入口含油浓度分层现象更明显,垂直位置上部和下部相对浓度差最大超过0.5,斜板上有油层流动,发生油层的破裂,大粒径油滴迅速浮升迁移。重力沉降区末端,垂直位置相对浓度差在0.2的小范围内波动。实验表明斜板聚结区域分散油滴的迁移浮升最为显著,水相出口处易形成涡旋流,引起重力沉降区域末端浮升迁移的小于10μm粒径分散油滴扰动和返混,需要进一步改进水相出口结构,稳定流场。