Response surface method to study the effect of conical surface and vortex-finder lengths on de-foulant hydrocyclone with reflux ejector

Abstract

The structure of the hydrocyclone always changes with the application scene due to its excellent separation performance. A de-foulant hydrocyclone with a reflux ejector (DFHRE) has a completely different flow field structure from that of a conventional one. Under the effect of the reflux ejector, DFHRE has the function of overflow-suck-underflow to achieve continuous discharge and high separation performance. To further improve its separation performance, an inner conical surface was added to control the turbulence intensity, and the suction angle and vortex-finder insertion depth were adjusted to control the intensity of the overflow-suck-underflow. The single factor method and response surface method (RSM) were used to conduct experiments through general-purpose polystyrene particles (GPPS) water and sewage. The results show that the separation performance of DFHRE first increased and then decreased as the lengths of conical surface Lc and vortex-finder Lv increase, whereas the separation efficiency and the energy consumption changed monotonically with the increase of suction angle α. For the results of RSM, these three factors (Lc, α, Lv) had significant effects on maximizing separation efficiency and minimizing split ratio, whereas their combined effects were not significant. Finally, the maximum separation efficiency and minimum total pressure drop optimized by the RSM model are 94.62% and 1.09 kPa, respectively. The optimal values of Lc, α, and Lv was 0.29 (height ratio of inner conical surface to that of the outer cone), 30°, and 0.50 (length ratio of the vortex-finder insertion to the total of cylinder-cone), respectively. Therefore, these three factors must be fully considered for designing DFHRE, and the insertion depth of the vortex-finder can exceed the interface of the cylinder and cone but not too much, which is different from that of the traditional hydrocyclone.