Numerical Simulation And Experimental Investigation Of Separation Performance Of Mini Hydrocyclone

The incomplete separation of small oil droplets by traditional oil-water hydrocyclone separators restricts the improvement of separation efficiency.To address this issue,the traditional oil-water hydrocyclone separator was scaled down based on the principle of geometric similarity.The basic structural form and parameters of the mini hydrocyclone were determined,and response surface method was used to optimize the structure of the mini hydrocyclone through numerical simulation.The results showed that when the overflow pipe diameter and large cone angle were 7.25mm and 15.28°,respectively,the separation efficiency was increased from91.15%of the initial structure to 93.77%.To enhance the separation accuracy and stability of a mini hydrocyclone,the optimal single mini hydrocyclone was further downscaled to a smaller main diameter mini hydrocyclone,and a two-stage serial system composed of two single mini hydrocyclones was constructed.Based on the single factor method,optimization simulation studies were carried out for the operational parameters of the optimal mini hydrocyclone and the two-stage serial system,including processing capacity,split ratio,water content,and oil droplet size.The flow field characteristics,including velocity distribution,oil phase volume distribution,underflow oil concentration distribution,and separation efficiency,were compared and analyzed.The results showed that the single mini hydrocyclone achieved the best separation efficiency of 99.90%at a processing capacity of 0.7 m~3/h and a split ratio of 55%.The simplification efficiency of the two-stage serial system and the single mini hydrocyclone both reached their maximum value at a total split ratio of 48%(primary split ratio 35%,secondary split ratio 20%).The simplification efficiency of the two-stage serial system was superior to that of the single mini hydrocyclone,and the two-stage serial system was more adaptable to low water content conditions.In order to alleviate the oil accumulation phenomenon in the vortex chamber of the mini hydrocyclone,structural modifications were made to the vortex chamber of the mini hydrocyclone.The oil volume fraction at the transition of the overflow pipe in the mini hydrocyclone increased slightly,and the oil accumulation phenomenon in the vortex flow was significantly improved.Indoor oil-water separation tests were performed on the single mini hydrocyclone,and the results showed that the mini hydrocyclone had efficient oil-water separation performance when the processing flow rate was 0.7 m~3/h and the split ratio was 55%,with a separation efficiency of up to 98.95%.This study verified the reliability of numerical simulation and provided optimization ideas for further improving the separation performance of mini hydrocyclones.