Performance optimisation of hydrocyclones with complex curved feed chambers: A CFD-experimental study

Abstract

Hydrocyclones are widely utilized solid-liquid separation devices that have been extensively applied in the coal, petroleum, and chemical industries due to their distinct classification advantages. The feed chamber, as a critical component of a hydrocyclone, significantly influences its separation performance. In previous studies, a single-line type was predominantly employed as the guiding curve for the feed chamber; however, such a configuration often fails to meet the requirements of particle motion, whereas a complex curved feed chamber structure can effectively address the limitations of a single-line design. Nevertheless, the impact of complex curved feed chamber structures on the separation performance of hydrocyclones has been scarcely investigated. Therefore, a hydrocyclone with a complex curved feed chamber structure was designed in this study. This structure integrates three geometric profiles—linear, involute, and spiral—in series to regulate the internal flow field and particle motion, thereby enhancing the separation performance of the hydrocyclone. Numerical analysis and experimental validation were conducted to examine the influence of the complex curved feed chamber on the internal flow field and separation performance of the hydrocyclone. The results indicate that: when the vortex finder is below a critical threshold, only a downward-moving external rotational flow exists, rendering the hydrocyclone ineffective for classification; the vortex finder insertion depth has negligible effects on static pressure and tangential velocity, although the outlet velocity variation rate is significantly influenced by the insertion depth; the pressure drop and turbulence intensity decrease with increasing apex diameter; the inlet aspect ratio has a significant impact on the stability of the flow field; the feed flow rate strongly affects the velocity and pressure fields; experimental results for a 75 mm hydrocyclone reveal that, with an increase in apex diameter, the underflow yield increases from 20.02 % to 35.18 %, and the −20µm fine particle content in the underflow increases from 5.07 % to 19.93 %, indicating a significant increase in fine particle entrainment; as the vortex finder diameter increases, the underflow concentration increases from 27.31 % to 49.18 %, and the overflow concentration increases from 8.12 % to 21.98 %, suggesting that increasing the vortex finder diameter can enhance slurry concentration; as the vortex finder insertion depth increases, the cut size increases from 32.3 µm to 43.1 µm, the overflow content of −20µm particles decreases from 46.58 % to 37.13 % (a reduction of 20.3 %), and the underflow content decreases from 15.63 % to 11.22 % (a reduction of 28.2 %). Thus, the approach of reducing fine particle content in the underflow by increasing the vortex finder insertion depth is not feasible.