聚结板强化油水分离过程的机理研究

中文摘要: 为从分散相油滴聚结机理的角度阐明板式聚结器强化油水分离过程的原理并为其设计提供依据，对油滴群在不锈钢斜板表面的聚结过程和油水两相在聚结板组内的分离过程进行了实验，研究分散相油滴在单一聚结板表面和聚结板组内的聚结行为及机理。结果表明：分散相油滴接触聚结板后将在表面形成凹凸不平的油滴层，而非连续流动的油膜；后续油滴通常难以直接融入油滴层，其中大油滴在油滴层表面主要以滚动方式离开聚结板，而小油滴则是通过嵌入凹凸不平的油滴层表面，并经过排挤水膜→聚并增长→形成随机流道→脱离聚结板的时间过程而实现分离。聚结板组对大油滴分离过程并强化作用，但可有效强化小油滴分离过程。且强化原理主要在于3个方面：缩短油滴浮升至聚结面的时间；在板表面形成凹凸不平的油滴层，为小油滴提供稳定的停留场所以完成聚并过程；为分散相小油滴的聚并提供足够的聚结面积。这一机理较好阐明了小油滴分离实验结果及其分率效率随聚结器结构参数的变化规律，即一定范围内，增加聚结板长度（增加有效聚结面积）或减小板倾角（促进油滴停留与聚并）都将提高分离效率。
Abstract:New insights were presented through systematic experiments for the coalescing behaviors of oil-droplet swarms on the surface of inclined plates and the intensifying mechanism of oil-water separation with plate pack.It is found that when arriving at the inclined plate,the oil-droplets clinging to the surface of plate will not form a continuous oil film as usually regarded,but a rugged surface consisting of dispersed droplets.The subsequent oil droplets will not coalesce directly into this layer.Large oil droplets will roll upwards on the surface of droplets-layer and then leave the inclined plate,while small oil droplets will be retained in some hollow place of the rugged surface and finally coalesced and separated from water after some time period,during which four consecutive stages took place:film drainage,coalescence and growth,forming a random channel,and leaving the plate.The principle of plate pack intensifying the separation of small oil droplets comes from three aspects:shortening the ascending-time that oil droplets arrive at the plate;providing the rugged surface composed by dispersed droplets so that the small oil droplets can find suitable places to stay and complete the coalescence process;offering sufficient coalescence area for small oil droplets.This principle explains the experimental results well for the separation of small size oil droplets.To some extent,the increase of the plate pack length leads to an increased coalescence area,while the decrease of the inclined angle of plate will benefit to the coalescence of oil droplets,and both helps improve the separation efficiency.