Effects of different cylinder roof structures on the vortex of cyclone separators

Abstract

To improve the internal flow field of a cyclone separator, grasp the effects of the cylinder roof structure on the flow field of the cyclone separator, and improve the separation efficiency, the research on the influence of different cylinder roof structures on the vortex of the cyclone separator was carried out. Through numerical simulations, the gas flow was simulated using the Reynolds stress model (RSM). The vortex of the cyclone separator captured by the Q criterion and Ω-method were compared. Based on the Ω-method, the vortex and separation efficiency of cyclone separators with three different cylinder roof structures were analyzed. The results show that compared with the Q criterion, the Ω-method captures the non-fractured iso-vortex surface inside the exhaust pipe, and can more accurately capture the vortex inside the cyclone. The iso-vortex surface of an Arc-shaped Cylinder Roof (ACR) cyclone separator has a smaller curvature, better continuity, and less distortion than that of a Flat Cylinder Roof (FCR) cyclone separator and Wedge-shaped Cylinder Roof (WCR) cyclone separator. The vortex lines and vorticity magnitude curves of the ACR cyclone separator are more regular, uniform, and symmetrical than those of the FCR cyclone separator and WCR cyclone separator. Compared with the FCR cyclone separator, the tangential velocity inside the ACR cyclone separator and WCR cyclone separator is greater. The positive radial velocity near the wall of the cylinder cone inside the ACR cyclone separator and WCR cyclone separator is greater. For the ACR cyclone separator and WCR cyclone separator, the positive axial velocity at the top of the cylinders, outside the wall at the lower end of the exhaust pipes, and near the wall of the cylinder cones is greater. The streamlines inside the ACR cyclone separator and WCR cyclone separator are more gentle and regular. For the ACR cyclone separator and WCR cyclone separator, the gas at the top of the cylinders flows obliquely downward along the roofs, which helps to suppress the top ash ring and short-circuit flow and improve the separation efficiency. Compared with the FCR cyclone separator, the separation efficiency of the ACR cyclone separator and WCR cyclone separator is increased by 24.66% and 14.06%, respectively. The research results provide useful guidance for the improvement of the cylinder roof structure and a reference for improving the flow field and separation performance of cyclone separators.