It has been reported that the overall efficiency of parallel cyclones is usually lower than that of an isolated single cyclone because of the cross flow (or cross talk) in the common dust hopper. To demonstrate the performance difference between a single cyclone and parallel cyclones, comparative experiments are conducted at a solid loading of 5 g/m(3) and inlet velocities ranging from 15 to 26 m/s. The parallel cyclones consist of four identical cell cyclones which are axial-symmetrically assembled. The results show that the overall efficiency of the parallel cyclones is higher, instead of lower, than that of a single one. And the pressure drop of the parallel cyclones is also higher by 16.8%. A numerical simulation on the flow field of the parallel cyclones further illustrates that no cross flow is found in the common dust hopper. And the tangential velocity of outer vortex in any cell cyclone is 7.0% greater than that in a single cyclone, resulting from an increase of the moment of gas momentum after the gas flowing through a right-angled turn. More interesting is that the vortex flow in each cell cyclone becomes more stable than in a single one, which plays a significant role in suppressing particle re-entrainment and promoting efficiency. Qualitative analyses on point vortices indicate that in a symmetrical vortex system, there exists a mechanism of inherent stability which helps to enhance the stability of vortex flow in each cell cyclone. (C) 2014 Elsevier B.V. All rights reserved.