Improvement of separation performance of the hydrocyclone with dual enlarged outlets and an arc overflow tube

The application of hydrocyclones can be traced back more than 100 years. Due to their unique advantages, they have been widely used in various separation industries. However, the classification efficiency of hydrocyclones is relatively low due to structural limitations. Therefore, improving the classification performance of hydrocyclones has become a research hotspot and challenge. As critical components, the vortex finder and underflow outlet significantly affect the classification performance of hydrocyclones. This paper designs a series of vortex finder and underflow outlet structures to improve classification accuracy. Numerical analysis and experimental verification methods are used, with pressure field, velocity field, turbulence field, and classification efficiency as evaluation criteria, to investigate the mechanisms underlying the classification performance of hydrocyclones with different structures. Results show that the pressure drop of the Type D (double outlet expansion) hydrocyclone is the smallest, indicating lower energy consumption under identical operating conditions, thereby reducing operating costs. The Type D with an arc vortex finder shifts the LZVV inward, enlarging the separation space for coarse particles while reducing it for fine particles. The circulating flow of the Type D hydrocyclone decreases by 2.26 percentage points compared to the Type A (Base) hydrocyclone, and the short-circuit flow decreases by 4.43 percentage points, resulting in a more stable internal flow field. Type D has a smaller cut size and a higher steepness index, demonstrating stronger cutting ability and higher classification accuracy. Experimental verification shows that the -6 mu m underflow content of the Type D hydrocyclone is 13.93 percentage points lower than that of the Type A hydrocyclone, while the -75 mu m overflow content decreases by 3.97 percentage points. The issues of fine particles in the underflow and coarse particles in the overflow are effectively mitigated. The data obtained in this study provide theoretical and empirical support for the development of novel hydrocyclone structures.