催化裂化提升管出口旋流快分系统内隔流筒结构的优化改进

 研究表明, 旋流快分系统(VQS)内旋流头上骑插筒形隔流筒(A型)后, 可消除其喷出口处短路流夹带颗粒的现象, 大大提高系统的分离效率. 但A型隔流筒底部还存在另一种短路流现象, 结构尚需进一步优化, 为此, 开发了折边隔流筒(B型)和锥型隔流筒(C型). 采用Fluent软件对VQS系统内气-固两相流进行了数值模拟, 重点考察了A、B、C型隔流筒的流场分布和分离效率. 模拟结果表明, C型隔流筒子的分离段外侧切向速度较大, 离心力较强; 内侧上行轴向速度较小, 气体向上夹带细粉的速度较低; 底部截面处向心径向速度较小, 基本为零, 有利于消除短路流. 因此, 工业应用中推荐采用C型隔流筒, 以进一步提高系统的分离效率.

IMPROVEMENT OF THE ISOLATE CYLINDER IN VORTEX QUICK SEPARATION SYSTEM AT FCCU RISER OUTLET

The short-circuit flow near the outlet of vortex head could be eliminated and separation efficiency of vortex quick separation system (VQS) could be increased effectively, after installation of isolate cylinder (model A) on the vortex head of VQS. And the situation of another short-circuit flow in the bottom of isolate cylinder (model A) indicated that the structure of isolate cylinder should be improved. The gas-solid flows, especially, the flow distribution and separation efficiency in VQS with different isolate cylinders (model A, B, C) were numerically simulated with the application of FLUENT software. Numerical calculation showed that in model C, not only the tangential velocity in outer vortex area was highest, but also the axial velocity in inner vortex area and the upward velocity of particle entrainment were lowest among those of the three models, which implied that model C had strong centrifugal force and high separation efficiency. Furthermore, the centripetal radial velocity of model C, which could cause short-circuit flow, was low, being useful to improve separation efficiency. Hence, model C was proposed to be the optimal isolate cylinder applied in industry.