耦合场渗透汽化过程的研究

发布时间：2018-05-03 08:16

本文选题：渗透汽化 + 电场　；参考：《天津工业大学》2017年硕士论文

【摘要】：渗透汽化技术是一种新型的膜分离技术,由于高效、节能、工艺简单、易于操作等优势,在有机物脱水、脱除水中少量有机物、有机物-有机物分离等方面被广泛应用。传统的渗透汽化过程遵循溶解扩散机理,往往是仅仅依靠调节膜两侧蒸汽压差来控制渗透物的传质速率,而本文通过在传统方式中引入不对称静电场的方法建立了耦合场渗透汽化过程模型,使传质过程得到了很大改善。本文主要考察了不对称静电场对不同极性渗透物传质过程的影响;探讨了不同方向的梯度场对渗透物传质过程的作用;并针对电场对膜结构参数的影响进行了分析讨论。本文以商品化聚乙烯醇膜为渗透汽化膜,分别对水、乙醇、正丙醇、异丙醇、正丁醇、异丁醇、乙酸乙酯、间二甲苯、对二甲苯等物质的耦合场渗透汽化过程进行了研究,分别从乙醇/水、不同体系有机物、同系物、同分异构体等角度讨论了电场对不同极性物质的影响。结果证明,在正向梯度场下,极性物质的通量和提高率都随着电场梯度正比例变化,变化的程度与渗透物种类相关,非极性物质的通量不受电场影响。对于水和乙醇来说,电场对水的促进作用更大:而对于不同体系有机物来说,电场对醇类的影响要高于酯类,而同系物中,一般分子量较小时,电场的促进作用较大,同时,也可以通过引入电场的方法,实现在提高一些同分异构体的通量的同时提高其分离性能的目的。实验还对梯度场方向的影响进行了讨论,结果表明正向梯度场对极性物质的传质过程有促进作用,而反向梯度场有牵制作用,但是两种情况下,电场对传质过程的影响程度相同。实验对加压前后膜表面元素和微结构进行了表征,结果表明,加压后膜材料的表面结构形态和断面结构形态并没有什么变化,膜表面的水接触角和化学键以及元素和元素含量都没有变化。
[Abstract]:Pervaporation technology is a new membrane separation technology. Because of its advantages of high efficiency, energy saving, simple process and easy operation, it is widely used in dehydration of organic matter, removal of a small amount of organic matter in water, and separation of organic-organic matter. The traditional osmotic vaporization follows the mechanism of dissolution and diffusion, and the mass transfer rate of the permeate is controlled only by adjusting the pressure difference between the two sides of the membrane. In this paper, the model of osmotic vaporization process of coupling field is established by introducing asymmetric electrostatic field in the traditional way, and the mass transfer process is greatly improved. In this paper, the influence of asymmetric electrostatic field on the mass transfer process of different polarity permeates is investigated, the effect of gradient field in different directions on the mass transfer process is discussed, and the influence of electric field on membrane structure parameters is analyzed and discussed. In this paper, the coupling field pervaporation process of water, ethanol, n-propanol, isopropanol, n-butanol, ethyl acetate, m-xylene and p-xylene were studied using commercial PVA membrane as pervaporation membrane. The effects of electric field on different polar substances were discussed from the angles of ethanol / water, organic compounds in different systems, homologues and isomers. The results show that the flux and the rate of increase of polar matter change with the positive proportion of electric field gradient under the positive gradient field, and the change degree is related to the permeable species, and the flux of non-polar matter is not affected by electric field. For water and ethanol, the effect of electric field on water is greater: for organic matter of different systems, the effect of electric field on alcohols is higher than that on esters, while in homologues, the effect of electric field is greater when the molecular weight is small, and at the same time, It is also possible to increase the flux of some isomers and improve their separation performance by introducing electric field. The effect of the gradient field on the direction of the gradient field is also discussed. The results show that the forward gradient field can promote the mass transfer process of polar matter, while the reverse gradient field can restrain the mass transfer process, but in both cases, The effect of electric field on mass transfer process is the same. The surface elements and microstructure of the membrane were characterized before and after compression. The results showed that there was no change in the surface structure and cross-section structure of the membrane before and after compression. The water contact angle and chemical bond on the surface of the film as well as the contents of elements and elements have not changed.
【学位授予单位】：天津工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ028.8

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