A Computational comparison of mini-axial and reverse flow hydrocyclone

Axial flow hydrocyclones are competitive to the standard reverse flow hydrocyclones in liquid-solid separation. A numerical investigation of simple mini axial and reverse flow hydrocyclone with 5mm diameter is presented here. The design configuration is referred to and modified from the existing literature 1,2. The Lagrangian approach was followed to solve the flow field, and for numerical study, the large eddy simulation (LES) model was employed. In the Lagrangian approach, the discrete phase model (DPM) was followed to analyse the discrete phase for the particles by releasing them from the inlet surface of both the hydrocyclones. For particle simulation, soda-lime glass particles of density 2520 kg/m 3 were injected with a diameter range of 10 µm ≤ DP ≤ 150 µm and the mean diameter of particles equal to 80µm. The numerical simulations were performed contemplating the same geometrical configuration for both the hydrocyclones to compare the pressure drop, separation efficiency, cut size(d50) and dimensionless numbers. The computational results of the velocity flow field, turbulence fluctuation and turbulence intensity were also compared between axial flow hydrocyclone and reverse flow hydrocyclone at the centre plane, considering the same flow velocity. The results indicate that the axial flow hydrocyclone has a low-pressure drop and higher cut off size than the reverse flow hydrocyclone at inlet velocities ranging from 1-10m/s. Figure 1(a) demonstrates with the increase in inlet velocity, the cut size linearly reduced from 66µm to 31µm and 65µm to 30.5µm for axial and reverse flow hydrocyclones, respectively. Figure 1(b) shows the pressure drop of the axial flow hydrocyclone increases from 1.2 kPa to 75.66 kPa and 1.198 kPa to 292.7 kPa for reverse flow hydrocyclone. According to the results, the simple design of axial hydrocyclone is effective for particle separation. Figure 1: Comparison of a) cut size (d50) and b) pressure drop between axial and reverse flow hydrocyclone for inlet velocities 1-10m/s. a School of Engineering & IT, UNSW Canberra @ADFA, ACT, Australia 1 Liow and Oakman, Miner. Eng. 122, 67 (2018). 2 Zhu et al., Chem Eng Res Des 90, 2135 (2012). 679 A computational comparison of mini-axial and reverse flow hydrocyclone.