含油污水聚结除油研究进展

介绍了含油污水处理的主要方法,以及根据油滴粒径的不同,含油污水中油的4种存在形式。从宏观方面介绍了聚结除油的2种机理——润湿聚结机理和碰撞聚结机理,并对2种聚结除油机理与材料表面性质的关系进行探讨。根据材料的表面性质,将聚结除油材料分为亲油材料、亲水材料及超疏水材料,综述了3类聚结除油材料的特点、除油效果及应用情况。对聚结材料在含油污水处理方面的应用进行展望,指出今后需进一步探索的方向是提高聚结材料对小粒径分散油和乳化油的去除率,深入研究聚结除油的机理,开发新型聚结材料。     

超重力水力聚结分离器流场分析与性能评估

采用离散相模型以脱油型水力旋流器为研究对象,分析了不同粒径油滴粒子在旋流场内的运移轨迹,得出随着粒径的增大旋流器的粒级效率逐渐升高。基于油滴运移轨迹设计了一种水力聚结旋流分离装置,可在旋流分离前端通过水力聚结使小颗粒油滴聚并成大颗粒油滴,进而增强旋流分离性能。开展室内试验对水力聚结分离器的分离性能和适用性进行验证。结果表明:粒径在100～900μm范围内随着油滴粒径的逐渐增大,旋流分离效率逐渐升高;水力聚结器可在油滴进入旋流分离器前使油滴碰撞聚结致使离散相油滴粒径分布增大,从而提高旋流器分离效率,其最佳入口进液量在4. 12m~3/h左右,最佳分流比为20%。     

聚丙烯共混改性对其聚结除油性能的影响

采用不同性质的添加剂(CPB、CTAB、PVDF、硅蜡和长链烷基硅油)对聚丙烯进行共混改性,研究了不同改性剂对聚丙烯材料表面亲油亲水性的影响,以及改性材料在油水分离过程中的聚结除油性能。结果表明,除PVDF外,同样添加量下的不同改性剂,或同一添加剂的不同添加量,改性聚丙烯的亲水角和亲油角之差越小,越有利于聚丙烯聚结除油性能的提高;由于PVDF的疏水疏油性,有利于改性材料表面油膜的流动、脱落,以及水中油滴的聚结,其对除油效率的提高要明显高于其它的改性剂。     

油田采出水聚结分离研究进展

聚结分离具有结构紧凑、使用成本低、处理量大等优点。本文概述了油田采出水的成分和特点以及油田常用采出水处理技术,综述了聚结技术发展历史、聚结机理研究进展、聚结分离装置现状以及聚结数值模拟研究进展,并对聚结机理和设备的研究进行了展望。     

化学驱污水聚结材料优选及影响因素研究

为了优选出聚结材料并应用于油田水处理，本文通过实验室聚结实验，使用自制模拟含油污水，对比分析PVC、PU、stainless和PA的聚结效能并探究水力条件及材料PPI对聚结效能的影响。结果表明，PU的聚结效能要高于其他3种材料，含油量去除率最高可达95%；水力停留时间在80min时趋于稳定，振荡频率在150r·min^-1时趋于稳定。经油田化学驱污水验证实验也得到相同结论。室内实验结果可以为工业上聚结材料种类、结构的选择以及水力条件的调控提供指导与参考。     

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。     

高效复合聚结板式油水分离器数学模型

通过对油水分离过程中油滴在聚结板间浮升和在聚结板表面聚结的过程机理的研究,建立了关于聚结板式油水分离器的油水分离过程数学模型,求得分散相液滴分离所需的时间。该模型充分考虑了油水两相的物性以及两相分层流动对分离过程的影响。     

聚结破碎模型在水力旋流器模拟中的应用与对比

为研究不同聚结破碎模型对油水分离水力旋流器内油滴粒径分布特性的影响,以双锥式水力旋流器为研究对象,采用计算流体动力学方法加载群体平衡模型,开展12种不同聚结破碎模型组合方案的数值模拟研究。通过开展室内分离性能及粒度分析实验对不同方案模拟结果进行筛选及验证。结果表明:luo聚结与luo破碎组合模拟得出的旋流器底流口油滴粒径体积分数最高在320μm处,占比为45%,与实验结果最接近,说明采用luo-luo组合模型模拟旋流器内油滴的聚结破碎特性较准确。旋流器内油滴粒径值由轴心到边壁呈环形对称的减小趋势,而湍动能变化呈环形对称的增大趋势;不同操作参数条件下luo-luo组合方案的质量效率模拟结果与实验值呈现出较好的一致性,均随入口处理量与溢流分流比的增大先升高后降低,且在处理量为5.23 m~3/h,分流比为30%时,质量效率达到最大值94.6%。     

油水重力分离原理及聚结破乳机理初探

对油水重力分离的基本原理进行了阐述,并对油水乳状液聚结破乳机理进行了探讨。分析表明,从浅池原理和聚结原理入手,可对分离器的结构和聚结板的材料进行优化,以提高其流动特性以及分离性能;若有效地分离油水两相,必须施加外力场,使得坚固的界面膜削弱并破坏,促进其聚结破乳;应根据聚结破乳发生的条件对分离器的结构进行优化,以保证其具有优良的水力特性。     

横向流聚结除油器的改造与应用

针对横向流聚结除油器在生产中出现的问题,对原横向流聚结除油器进行改造,该设备采用两级聚结板-分离板除油区和一级聚结原件除油区形成三级除油系统,改造后的横向流聚结除油器能够有效除油,节约了油田生产成本,处理后出水水质良好。     

Hydrodynamics and morphologies of droplets coalescence on fiber

Fiber coalescence is an effective oil–water separation technology. In this article, the micro-coalescence process of droplets on fiber was studied through high-speed camera technology, and the hydrodynamics and morphology evolution in the process of droplet-fiber coalescence were explored and compared with non-fiber system. The results show that the change of the droplet surface morphology is local at the initial stage of the coalescence process. The droplet morphology changes obviously near the neck. The growth rate of the liquid bridge and the propagation speed of capillary wave in droplet-fiber system are higher than those in non-fiber system. At 0.8 ms, the capillary waves' polar angle difference between the two conditions reaches 10.44°. There is an obvious periodicity and damping attenuation mechanism in the oscillation process. In the droplet-fiber system, the oscillation process attenuates faster and the average oscillation period is shorter. The droplet relaxes to a stable state more quickly.     

拟塑性非牛顿流体中在线气泡聚并规律

以拟塑性羧甲基纤维素钠(CMC)水溶液作为非牛顿流体,对在线上升气泡的聚并规律进行了研究。利用光电信号采集系统测定了不同高度的气泡聚并分布规律,分析了气体速度及流体性质等因素对聚并规律的影响。结果表明,在测量高度和实验气速范围内,随着高度升高,在高气速下,气泡聚并率减小,在低气速下,则先增大后减小。2种情况下,达到一定高度后均趋于恒定;在一定高度下,达到一定气速后,气泡聚并率变化较小;中低气速下,聚并率随CMC质量分数增大而减小,而在高气速下,CMC质量分数变化对聚并率影响较小。     

苯酚浓度对亲油疏水型滤材聚结性能的影响

为探究油品中非烃化合物对滤材聚结性能的影响，在固定含水量1000?10?6(wt)的油水乳状液中添加不同浓度的苯酚，研究亲油疏水滤材的除水效率及过程压降。结果表明，实验过程中滤材的压降有3个阶段：油品对滤材的润湿及水膜初步形成、滤材中水膜形成并稳定、水珠脱落与聚结的动态平衡。随苯酚浓度增加，滤材从疏水态经过渡态逐渐转变为亲水态，苯酚与水摩尔比约为1:3.3时，疏水态向过渡态转变，苯酚与水摩尔比约为1:1.6时，过渡态向亲水态转变，C6H6O(H2O)2是苯酚?水团簇最稳定的结合方式。     

微通道内纳米颗粒对液滴聚并的影响规律

Pickering 乳液是纳米颗粒稳定的液液两相体系,微流控技术是制备单分散Pickering 乳液的有效方法,而含有纳米颗粒体系在微通道内的液滴聚并规律是该实施方法的关键科学问题之一。以正辛醇为连续相,水为分散相,研究了六边形扩大微通道内液滴碰撞过程,发现了液滴聚并、碰撞不聚并和不相互接触3 种流动状态,研究了流量、颗粒浓度和颗粒亲疏水性对于液滴聚并率的影响规律,分析了颗粒在液膜排空过程中的作用机理。     

The effect of temperature on coalescence of liquid drops at liquid/liquid interfaces

Drop/interface coalescence times measured at 293–343K are reported for three oil/water systems (benzene, paraffin oil and 1,1,2,2-tetrabromoethane) with different interface ages. The anomalous coalescence behavior of water droplets is explained by considering the static electrical double-layer residing at the interface which influences the film thinning and the film rupture processes. Analyses using simplified coalescence models reveal that the incorporation of temperature dependence on the physical properties such as density difference between phases, viscosity of the continuous medium and interfacial tension, does not produce satisfactory agreement with the measured coalescence times. The effect of mutual saturation in contrast to unsaturated systems on coalescence times is illustrated. The reproducibility of the drop/interface coalescence times is examined and explanations are offered, relating the method and the conditions of the experimentation. Finally the importance of both the coalescence time and the film thickness to drop stability analysis is demonstrated.     

Enhanced coalescence separation of oil-in-water emulsions using electrospun PVDF nanofibers

A novel and high-efficiency coalescence membrane enhanced by nano-sized polyvinylidene fluoride(PVDF) nanofibers based on polyester (PET) substrate was fabricated using electrospinning method.The properties of the electrospun nanofibers such as roughness and surface morphology greatly affected the oil droplet interception efficiency and surface wettability of the membrane.A series of coalescence units were prepared with different layers of nanofibrous membrane and the separation efficiencies at dif-ferent initial concentrations,flow rates,and oil types were tested.It is very interesting that the obtained nanofibrous membrane exhibited superoleophilicity in air but poor oleophilicity under water,which was beneficial to the coalescence process.The coalescence unit with four membrane layers had excellent per-formances under different initial concentrations and flow rates.The separation efficiency of the 4-layers unit remained above 98.2％ when the initial concentration reached up to 2000 mg·L-1.Furthermore,the unit also exhibited good performance with the increasing oil density and viscosity,which is promising for large-scale oil wastewater treatment.     

An experimental study of factors which promote coalescence of two colliding drops suspended in water-I

The factors which determine whether two colliding drops will coalesce or rebound have been studied experimentally for 3.4 mm dia. anisole drops in water, using an apparatus designed to permit control of drop size, impact velocity and collision angle. Analysis of high speed movies showed that for relative approach velocities of 1.9–11.2 cm/sec, the apparent drop contact time was less than 70 msec. The probability of coalescence during this short time interval was a function of the phase and amplitude of the drop oscillations at moment of contact. The results have been analyzed using a modification of the conventional Stefan-Reynolds type film thinning equation derived for rigid interfaces. This relationship, although indicating more thinning for coalescences than rebounds, fails to predict fast enough thinning rates to validate the model. Part II gives detailed derivations for a thinning model in which interfaces are free to move, and shows how the results given in Part I can be explained by film thinning.     

二元液滴自由碰撞聚并后的振荡行为研究

以甲苯、超纯水为多相系统研究对象，采用高速摄像机测试分析了二元液滴自由碰撞聚并后的振荡行为特性。实验结果表明，聚并后甲苯液滴振荡过程存在明显的周期性与阻尼衰减机制，液滴Reynolds数、Weber数是影响聚并后液滴振荡周期、阻尼系数的关键无量纲参数。液滴惯性力与振荡周期呈正相关性，而液滴黏性力则主导了振荡过程的阻尼衰减机制，振荡阻尼系数随黏性力的增加而增加，同时，液滴碰撞聚并作用与其后续振荡过程相对独立，即碰撞聚并过程对液滴振荡行为特性无明显影响。此外，液滴振荡过程特性参数的实验与理论计算对比结果显示，振荡周期实验结果相较于理论值略微偏高，振荡周期、阻尼系数实验与计算值相对误差的标准差分别为14.9%和44.9%。     

旋流场中聚结过程研究

在对旋流场内多相流的分析,包括分散液滴的受力和运动分析的基础上,研究了旋流聚结的机理,并通过试验验证了旋流场内聚结过程的存在,且发现在某一进料流量时聚结效果特别明显,即存在最佳进料流量或入口雷诺数。     

Time-dependent density functional study for nanodroplet coalescence

The coalescence of nanodroplets is an important interfacial phenomenon and is the key to many real-world applications. However, the microscopic mechanism for this process remains unclear. In this work, we propose a time-dependent density functional theory (TDDFT) to understand and predict this process. The formation of a “peanut” nanodroplet seems key to the coalescence process, before and after which the system is dominated by a nucleation mechanism and an ordinary diffusion mechanism, respectively. It appears that molecular attraction is not only the driving force but also the resistance of droplet coalescence. The velocity distribution indicates that there is a significant mass transfer on the vapor–liquid interphase. During coalescence, there is a clear linear correlation between the free energy and the surface area of the vapor–liquid interface, which means surface tension is the dominant contribution to the free energy.