Abstract: It is difficult to guarantee the separation accuracy of oil-water hydrocyclone under the condition of ultra-low inlet flow rate, an innovative micro-hydrocyclone is proposed to solve this problem. The prototypes of micro-hydrocyclone are manufactured by 3D printing technology to carried out the indoor separation performance experiment. Meanwhile, the significance of structural parameters affecting the micro-hydrocyclone separation performance are calculated based on the Plackett-Burman design method. The order of the significance of structural parameters on the oil concentration of underflow is obtained. The mathematical relationship model between the structural parameters and oil concentration of underflow is established by using the steepest climbing design and the response surface methodology. Furthermore, the mathematical relationship model is solved based on the least square method, the optimal structural parameters which can improve the separation performance of micro-hydrocyclone is obtained. The separation performance experiments are carried out under the conditions of different split ratio, inlet flow rate and oil concentration to compare the optimal micro-hydrocyclone with the initial one. The experimental results show that the maximum separation efficiency of the optimal micro-hydrocyclone is 99.85% when the overflow split ratio is 30%，inlet flow rate is 1.0 L/min and oil concentration is 2%. The separation performance of the optimized hydrocyclone is higher than that of the initial one, obviously. The experimental results not only verify the accuracy of the results of response surface methodology, but also prove that the proposed micro-hydrocyclone can achieve oil-water efficient separation under the condition of ultra-low inlet flow rate.

Key words: micro-hydrocyclone, structural parameter, response surface methodology, inlet flow rate, separation performance