【作者】 王尚文；

【导师】 陶涛；

【作者基本信息】 华中科技大学 ， 市政工程， 2007， 硕士

【摘要】 乳状液是一种或几种液体以液滴形式分散在另一种与之互不相溶的液体中构成具有相当稳定度的多相分散体系。乳状液分为油包水(W/O)型和水包油(O/W)型。随着石油和化工工业的发展,日益增多的乳状液需要进行破乳。目前破乳的方法有:加热破乳、研磨破乳、润湿聚结破乳、微波破乳、破乳剂破乳、膜法破乳、电场破乳等。针对这些破乳方法尤其是电破乳方法的不足,本课题提出了新型电极高压脉冲电场破乳法。本研究采用的新型电极由环氧树脂/钛酸钡(EP/BT)复合材料覆盖铜棒构成。模拟乳状液是煤油和水按1:1体积比混合,以Span80为乳化剂配制而成的W/O乳状液。破乳电场由高压脉冲电源提供,其电压范围为8~22kV,频率为50Hz以下。试验测定了复合材料的介电常数,并分析了电场特征。研究了各因素对破乳率的影响。研究结果表明:复合材料的介电常数随其配比升高而升高,在67%附近达峰值。电极绝缘材料、外加电压、破乳时间、气温对破乳率都有不同程度的影响,随着电极复合材料配比的升高,破乳率上升,40%时最高,但80%反而有所下降;电压是对破乳率影响最大的因素,随着电压升高,破乳率不断上升,22kV时破乳效果最好;随着破乳时间的增加,破乳率不断上升,但其增长速率不断降低;温度越高,破乳率越高。三因素、三水平的正交试验结果表明:采用3#(40%)电极、在电压22kV条件下5min的破乳效果最好。本文在临界电场强度的基础上提出了“临界液滴直径”的概念。结合乳状液内相水滴的正态分布情况推导出一个关于外加电场强度的函数,这个函数表达了给定电场强度下的破乳率。它很好地解释了本研究中的试验现象,具有较高的应用价值。最后本文针对试验中遇到的困难和未能解决的问题,提出了建议,以期对以后的研究有一定的借鉴作用。更多还原

【Abstract】 Emulsion is a comparatively stable multiphase dispersive system which is composed of several liquids. In this system, one or several liquids disperse into another insoluble liquid. There are two kinds of emulsion: water-in-oil (W/O) and oil-in-water (O/W).As the development of petroleum and chemical industry, more and more emulsion needs to be broken down. Currently the applied methods of demulsification include: heating demulsification, grinding demulsification, wetting coalescence demulsification, microwave demulsification, demulsifier demulsification and membrane demulsification. In this work, the demulsificatuion method by high-voltage pulsed electric field (HPEF) applying new types of electrode was investigated.In this work, The new types of electrode were made by copper sticks covered with epoxide resin/barium titanate (EP/BT) composite materials. Model emulsion was made from kerosene and water (1:1 by volume) with Span 80 as emulsifier, it is a type of W/O. The voltage of the electrical source generating electric field ranged form 8 to 22 kV, and its frequency was less than 50Hz. Permittivity of composite materials were measured, electric field character was analysed, and effluence of various factors on demulsification rate were investigated. The result of this study indicates: The permittivity of composite materials increases as the content of barium titanate increases, and it reaches the peak value when the content is near 67%. And all of the factors such as dielectric composite materials, applied voltage, time, air temperature affect demulsification rate to varying degrees. The demulsification rate increases, as the content increases, and it reaches peak value when the content is 40%, however, it decreases when the content is 80%; The applied voltage is the most vital factor. As voltage rises, the demulsification rate increases continuously, and when voltage value is 22kV, the effect of demulsification is the best; As time increases the demulsification rate increases continuously, and the rising rate becomes lower and lower; The higher the air temperature, the higher the demulsification rate under the experimental conditions; In the work, an orthogonal experiment involving three factors, each at three levels was designed. And the result of orthogonal experiment shows that the condition combination is 3# electrode +22kV voltage+5 minutes is the optimum one.In this paper, a new concept of critical droplet diameter was proposed on the basis of critical electric field intensity. And according with normal distribution of internal phase droplet, a function on applied electric field was deducted. The demulsification rate under a given electric field intensity can be expressed by this function. Some experimental phenomena in this reseach were explained very clearly. Also it has high value in application field.At last this paper presents some suggestions to some difficulties and unresolved problems in oder to suppy valuable refernces for the further study.更多还原