The effect of the dust outlet geometry on the performance and hydrodynamics of gas cyclones

Four cyclone separators with different dust outlet geometries (without dustbin, with dustbin, with dipleg and with dustbin plus dipleg) have been computationally investigated. There are two purposes of this study. First, to study the effect of changing the dust outlet geometry on the flow field pattern and performance of air cyclones. Second, to demonstrate whether simulation of the flow without accounting for the dust outlet geometry (i.e., simulate only the cylinder on cone region) is sufficient for performance estimation. Results show that the maximum tangential velocity is almost the same for the four tested cyclones. No radial acceleration occurs in the cyclone space (the maximum tangential velocity is nearly constant throughout the cyclone). Three cyclones (without dustbin, with dipleg and with dustbin plus dipleg) exhibit the inverted W axial velocity profile. An inverted V axial velocity profile is observed for the cyclone with dustbin. Although the absence of the dust outlet geometry from the simulation domain will result in large savings in the computational effort, the present study indicated it can affect the estimated pressure drop and cut-off diameter significantly. If the cyclone performance parameters are estimated without the dust outlet geometry, an error margin of around 10% in the calculations of the Euler number and 35% in the calculation of the cut-off diameter should be taken into account.

► The maximum tangential velocity is not affected by the dust outlet geometry.
► The shape of the dust outlet geometry affects the axial velocity profile.
► Including the dustbin in the simulation is essential for flow field investigation.
► Neglecting the dustbin results in 10% error margin in the Euler number.
► Neglecting the dustbin results in 35% error margin in the cut-off diameter.