Numerical analysis of axial flow cyclone for steam and droplets separation in saturated steam turbine

Abstract

ABSTRACT In this paper, an axial flow cyclone separator is employed to separate the droplets entrained in saturated steam turbine. The Eulerian–Eulerian approach and the Reynolds stress model are combined in numerical simulation. Then, the effects from the vane exit angle and the length of separation section on the separation performance are investigated, respectively. The distributions of pressure and velocity in the cyclone are presented in detail to describe the characteristics of flow field. The results demonstrate that the separation efficiency could be effectively elevated to 95% either by reducing vane exit angle or by increasing the inlet-velocity. In addition, the promotion brought by reducing the vane exit angle is larger than that of increasing inlet-velocity once comprehensively assessing pressure drop and separation efficiency. Furthermore, it is found that the designed the length of separation section should not be too short to reduce the steam leakage ratio, considering that the steam is flowed into the saturated steam turbine. The leakage ratio would decrease by 15% as the aspect ratio of separation section increases from 1.5 to 3.5. The improvement of separation efficiency can effectively reduce the damage of the steam turbine and improve its operational safety.