Structure Optimization And Performance Study Of Crossflow Filtration Hydrocyclone

With the continuous increase in the development and utilization of offshore oil resources in China,the accidents of oil spill in the sea frequently occur.If the oil can not be disposed quickly and efficiently,it will cause serious pollution to the marine environment.In order to effectively improve the quickness and high efficiency of oil-water separation in the process of oil spill,and at the same time make the whole treatment process more simple and compact,a new type of oil-water separation equipment--crossflow filtration hydrocyclone is studied in this paper.The equipment combines swirling and filtering to make them promote each other in the separation mechanism,and its function is also turned from single to pluralism.Therefore,carrying out the research on the crossflow filtration hydrocyclone has a high engineering practical value for rapid and efficient treatment of oil spills at sea.However,the few studies that have been conducted so far focus on the feasibility of using the equipment for oily wastewater treatment,there are few studies on the optimization of structure and operating parameters.In order to provide a theoretical basis for the structural design of the crossflow filtration hydrocyclone,the numerical simulation in the inner flow field particle size distribution of the conventional hydrocyclone with double cone is carried out first.The CFD-PBM(Population Balance Model)was used to the numerical simulate,it was found that in the conventional hydrocyclone with double cone,when the inlet flow exceeds a certain value(1.5 m3/h in this thesis),the average particle size of the oil droplets no longer increases but decreases.With the increase of the viscosity of the oil phase,the effect of breaking and coalescence of the droplet particles will be weakened.Besides,the effect of coalescence decreases with the increase of overflow ratio.The conclusion is in good agreement with the conclusion of the experiment,and the simulation method is reliable.Based on the basic structural scheme of crossflow filtration and the structural characteristics of the conventional hydrocyclone with double cone,the preliminary structure of the crossflow filtration hydrocyclone was established.The response surface method was used to optimize the structure of the key structure,and finally the optimal structure parameters of the crossflow filtration hydrocyclone were determined.Through the analysis of the optimized structure,it was found that there is a certain pressure difference inside and outside the crossflow filtration hydrocyclone porous filter material,and the pressure change of the liquid in the porous filter material shows a good linear relationship.The inlet flow rate,inlet oil droplet size and the viscosity have a significant effect on the underflow oil-water separation efficiency of the crossflow filtration hydrocyclone,but have little effect on the filtration oil-water separation efficiency.By comparing the crossflow filtration hydrocyclone with the conventional hydrocyclone with double cone which has the same structural parameters,it was found that the pressure in the conventional hydrocyclone with double cone reaches its maximum at the side wall in the tail pipe section,While the pressure in the crossflow filtration hydrocyclone reaches its maximum at a distance from the wall and then begins to decrease.The maximum tangential velocity of the crossflow filtration hydrocyclone is less than that of the conventional hydrocyclone with double cone.At different inlet flow rates and inlet oil concentrations,the oil-water separation efficiency of filtration flow in the crossflow filtration hydrocyclone were relatively stable,and are maintained at a very high level,indicating that the performance advantages of filtration flow in the crossflow filtration hydrocyclone.In this paper,a crossflow filtration hydrocyclone is developed from the point of view of "principle → structure→ performance",which provides a necessary technical support to upgrade the oil-water separation equipment for offshore oil spill treatment and improve the oil-water separation efficiency of oil spill treatment equipment.