In this study, the performance of a fast gas-solid separator was simulated based on the commercial software Fluent 6.2. The tangential velocity dominated the three-dimensional gas velocity, and decreased with the increase of the circumferential angle and radial position. In the separator housing, the swirling gas flow is similar to a modified or quasi free vortex. In the gas outlet tube, gas swirls with a rotation direction reverse to that in the separator housing. The ratio of circulation gas flow rate over the inlet gas flow rate changed only slightly with the increase of the inlet gas velocity, remaining at approximately 0.49. There was a stagnant particle layer on the separator base, inducing particle re-entrainment by circulation gas. In the present study, the separation efficiency of fine particles decreased with increasing inlet gas velocity, approximately remaining a constant as the particle diameter is greater than 12.5 mu m. (C) 2015 Elsevier B.V. All rights reserved.