Experimental study of circulation flow in a light dispersion hydrocyclone

• The zero axial velocity wave zone was determined as the location of circulation flow.
• The new calculation equation proposed for circulation flow rate.
• Analysis of the effect of geometric and operating parameters on circulation flow.

The circulation flow, in light dispersion hydrocyclones and the effects of various parameters on this flow were studied quantitatively through measurements of the axial velocity field. A phase Doppler particle analyzer (PDPA) system was developed to measure the axial velocity field in axial cross sections in ∅∅ 35 mm hydrocyclones with various vortex finders lengths, overflow orifice diameters, cone angles, inlet flow rates, and split ratios. The results showed that the zero-axial-velocity wave zone (ZAVWZ), which is responsible for the coupling of circular and closed flow in most axial cross sections, is caused by the velocity gradient and can be described as the location of the circulation flow. The mechanism of circulation flow and cyclone separation was revealed by the formation mechanism of the circulation flow. A new equation for calculating the circulation flow rate is proposed. By studying the effects of the geometric and operating parameters on the circulation flow, it was observed that smaller distribution areas and rates of circulation flow usually result in higher separation efficiency in a hydrocyclone.