开排沉箱内油水两相动力学模型实验研究

摘要

Through experimental study on distribution of oil concentration and oil droplet size,as well as vertical distribution of heat transfer temperature in open drain sump caisson,This paper studied the mechanisms of oil droplet collision coalescence and shear breakage as well as the vertical temperature distribution inside the open drain sump caisson,in combination with the oil/water two-phase flow and oil droplet force conditions between ramps.Study results indicate that ramps could form a static area and capture the oil droplets in sewage.However,the spoiler effect of ramps will further break up oil droplets while enhancing oil droplets collision coalescence.Hence,it is considered to install rectifier components at the ramp baffle place to reduce the breakage of oil droplets;once the coalescence effect of oil droplets is higher than the breakage effect,the macroscopic improvement on separating performance will be observed,but conversely,the emulsified backmixing will be observed and the separation mainly occurs at the ramps static area.Therefore,it is recommended to increase the area and quantity of static spaces during open drain sump caisson design.Due to influence of ramp spoiler,heat transfer on the ramp will be intensified by the strong turbulent flow field,and the temperature gradient here is higher than that of straight pipe section.Accordingly,heat preservation measures shall be taken to enhance corrosion control.The study results of this paper can be used to provide references for the internal structure optimization of open drain sump caisson and offer optimal operation parameters for the actual production and water treatment process.Meanwhile,temperature field measuring and analyzing can also do benefit to alleviate the corrosion resulted by the temperature differential under severe ocean conditions.%通过对开排沉箱内水中含油浓度分布、油滴粒径分布及传热温度垂直分布的实验研究,结合斜板间油水流动及油滴受力情况,分析了油滴碰撞聚结与剪切破碎的机理以及开排沉箱内温度垂直分布情况.结果表明,斜板能够构造静态区,捕集污水中的油滴,但由于斜板的扰流作用在促进油滴碰撞聚结的同时也导致油滴更容易破碎,因此可考虑在斜板折流处增设整流构件以减少油滴的破碎;当油滴聚结作用大于破碎作用时,则宏观表现为分离性能的提高,反之则会乳化返混,且分离过程主要发生在斜板静态区,故在开排沉箱设计时应增设静态空间区域和数量;受斜板扰流的影响,传热在斜板区会受到强湍流场的强化作用,温度梯度比直管段会更大,应增加保温措施来加强防腐.本文研究成果可为开排沉箱内部结构的优化提供参考,为实际生产及水处理工艺提供优化操作参数,同时温度场测定分析还为能应对由恶劣海洋环境下因温差产生的腐蚀提供防腐方案.