PERFORMAX聚结板油水分离性能数值模拟

Numerical simulation of oil-water separation performance in PERFORMAX coalescer

采用计算流体动力学方法,考虑液滴碰撞时的聚结与破碎过程,对PERFORMAX聚结板进行了数值模拟,研究PERFORMAX聚结板的分离特性,得到了聚结板数量、流速、粒径对聚结板分离效率的影响规律。研究结果表明,增加聚结板数量有利于提高分离效率;当流体处于层流状态时,以重力分离为主,PERFORMAX聚结板分离效率随粒径增加而急剧增加,当粒径大于50μm后,分离效率接近100%;而流体处于湍流状态时,惯性分离占据主导地位,PERFORMAX聚结板分离效率随粒径变化幅值很小;当粒径较小时,湍流分离效率高于层流;当粒径较大时,层流分离效率高于湍流;聚结板分离效率随速度的变化出现两个峰值,第一个峰值的主导作用力为重力,第二个峰值为惯性力;因此,粒径较小时适合采用惯性分离,粒径较大时适合采用重力分离;惯性分离涉及到碰撞,而碰撞过程易产生破碎,导致分离效率下降,当流速进一步增加时,由于液滴破碎,分离效率略有下降,但流速应控制在不使液滴产生破碎的范围内;PERFORMAX聚结板用于污水除油时的分离效率高于油中除水,但油密度对污水除油分离效率的影响并不显著。

The separation performance of the PERFORMAX coalescer was studied by using the computational fluid dynamics method.In this study,Ansys Fluent software was used,and the coalescence and breakup models were included.The influences of coalescer’s number,separation velocity,and droplet size on the separation efficiency weve obtained.The results showed that the separation efficiency was improved with the increase in coalescer’s number.The separation efficiency of PERFORMAX coalescer increase greatly with the increase in droplet diameter under laminar flow condition,which is corresponding to gravitational separation,but the increment is not obvious when the droplet diameter is greater than 50μm.The separation efficiency increases a little with the increase in droplet diameter under turbulent flow condition,which is corresponded to inertial separation.The results showed that the inertial separation efficiency is higher when the droplet diameter is less than 20μm,otherwise,the gravitational separation efficiency is higher.Therefore,if the droplet diameter is small,the inertial separation could be a good choice,Coalescence plate separation efficiency changes with the speed of two peaks,the first peak of the dominant force of gravity,the second peak is the inertial force.When the flow rate is further increased,the separation efficiency decreases slightly due to the broken droplels.But the separation velocity should be lower than the critical breakup velocity because inertial separation involved collision,which may easily cause droplet breakup.The separation efficiency of PERFORMAX coalescers used in the process of removing oil from produced water is higher than that of removing water form oil.With the decrease in oil density,the separation efficiency is increased gradually.But this change is not distinct for the density variation between different types of oil is not too large.