Experimental Investigation of Entrapped Water Droplets in Wax Deposition from Water-in-Oil Emulsion Considering Wax Crystals Adsorption at the Oil-Water Interface
Experimental Investigation of Entrapped Water Droplets in Wax Deposition from Water-in-Oil Emulsion Considering Wax Crystals Adsorption at the Oil-Water Interface
复制标题
考虑油水界面蜡晶体吸附的油包水乳液蜡沉积中截留水滴的实验研究
DOI：
10.1021/acs.energyfuels.9b03804
复制
发表时间：
2020-02-01
期刊：
影响因子：
5.3
通讯作者：
Gong, Jing
中科院分区：
文献类型：
--
作者：
Ma, Qianli;Wang, Wei;Gong, Jing
油包水型乳状液在管道中的蜡沉积问题是近年来引起人们广泛关注的一个问题。本研究探讨了蜡沉积与水滴的形成，考虑界面吸附的蜡晶体。将制备的20体积%油包水乳液用于蜡沉积实验，分析沉积质量/厚度和沉积中水的体积分数，确定在整个沉积持续时间期间沉积中水的含量是恒定的并且等于乳液中水的含量。利用偏光显微镜对蜡沉积物的微观结构进行了观察，发现有些水滴由于界面吸附而被蜡晶覆盖，有些水滴则被蜡晶网络包裹。根据这些发现，提出了两种类型的沉积液滴的截留。一个包含晶体网络的形成和生长，伴随着这些蜡覆盖的水滴本身;另一个表明水滴被晶体网络包围，导致这些水滴的运动受到限制，因此水滴在沉积中沉降。此外，还比较了用显微镜测量沉积物中水滴的分布和用聚焦光束反射法测量乳状液中水滴的分布。据观察，与这些大液滴相比，这些小液滴更有可能被并入沉积物中。测得的截留水滴的最大尺寸为115 μ m，这与先前的研究结果一致，该研究声称并入沉积物的水滴的一般直径不超过100 μ m。蜡晶的界面吸附为研究蜡沉积中的水滴提供了一个新的视角。
The presence of water in wax deposition from water-in-oil emulsion for petroleum transportation in pipelines has received much attention in recent years. This study investigated the formation of wax deposition with water droplets, considering interfacial adsorption by wax crystals. The prepared 20 vol % water-in-oil emulsion was used for the wax deposition experiment with an analysis of deposition mass/thickness and water volume fraction in deposition, determining that the water content in deposition during the whole deposition duration was constant and equaled to the water content in emulsion. Moreover, a polarizing microscope was employed to observe the microstructure of wax deposition, revealing that some water droplets were covered with wax crystals due to interfacial adsorption, while some droplets were enclosed by the network of wax crystals. Depending on these findings, two kinds of entrapment of water droplets in deposition were proposed. One contained the formation and growth of a crystal network accompanied with these wax-covered water droplets themselves; another one indicated that water droplets were surrounded by a crystal network, resulting in the movement of these droplets being limited and therefore the droplets settling in deposition. Furthermore, a comparison of the distribution of water droplets in deposition using a microscope and that in emulsion by focused-beam reflectance measurement was presented. It was observed that these small droplets were more likely to be incorporated into deposition in contrast with these large ones. The largest size measured for an entrapped water droplet was 115 mu m, which was in accordance with the previous research claiming that the general diameter of water droplets incorporated into deposition was no more than similar to 100 mu m. Interfacial adsorption of wax crystals provides an additional insight to investigate water droplets in wax deposition.