Three-dimensional flow field in the vortex quick separation system of FCC disengager is simulated based on the Differential Stress Model（DSM）provided by CFX5

is studied firstly to improve the separation efficiency.Predictions with the Differential Stress Model are in reasonable agreement with experimental results measured by intelligent five-hole probe

attesting to the suitability of Differential Stress Model for simulating flow field in the vortex quick separator. Both the numerical calculation and the experimental results show that turbulent flow field in the vortex quick separator is symmetric.There is a short-circuit flow near the outlet of the vortex quick separator

which has negative effect on the particle separation and is a key factor to decrease the separation efficiency.The configuration dimensions (S) and the characteristic angle (α) of the vortex head have influences on the tangential velocities in the vortex quick separation system

so they should be optimized. The stripping gas has a little effect on the gas-solid separation efficiency and can be beneficial for discharging the gas.