新型静电聚结器中水滴聚结特性研究

Investigation on Coalescence Characteristics of Water Droplets in New Type Electrostatic Coalescer

传统电脱水器采用裸电极,含水率较高时在高强电场作用下容易发生击穿现象,今设计了包覆绝缘层的高压电极并加工了新型静电聚结器,可有效避免击穿现象的发生。采用水/原油乳状液为实验介质,并利用显微高速摄像系统结合图像处理技术对水滴的聚结规律进行了观察和分析,探索了电场强度、流量、含水率等因素对水滴聚结特性的影响。结果表明:包覆绝缘层的高压电极可有效防止电击穿现象的发生,增加电场强度有助于油水分离,但高于临界场强后容易导致液滴破碎;含水率为10%、20%、30%时,最优电场强度不同,分别是372、320和204 kV m 1;含水率10%和30%乳化物液滴粒径增大倍数明显大于含水率20%的工况;电场作用时间影响液滴聚结效果,高强电场在低流量下具有很显著的作用;随着流量的增加电场作用降低,但高强电场在高流量下依然使液滴粒径明显增大。

Traditional electric dehydrator with bare electrodes is easily broken down by high voltage when the water content is high. The insulated electrode and new type electrostatic coalescer were designed to avoid the breakdown of electric field. The coalescence characteristics of water droplets under high AC electric field were investigated with water in crude oil emulsion as experiment medium. The micro high-speed camera system and image processing technology were also used to analyze the droplet size in the entrance and outlet of electrostatic coalescer. The effects of electric field intensity, flow rate and water content on the coalescence of water droplets were investigated. The results indicate that the insulated high voltage electrode can effectively prevent electric field breakdown. High electric field intensity is beneficial to the coalescence of water droplets, but if the electric field intensity is higher than the critical one, the water droplets will rupture. The optimal electric field intensities vary with water content, and the optimal electric field intensities decrease with the increase of water content. The coalescence of water droplets is associated with residence time, and high electric field intensity can dramatically facilitate the coalescence of water droplet under low flow rate. With the increase of flow rate, the effect of electric field intensity is weakened, but high electric field intensity can still effectively promote the coalescence of water droplets.