FCC沉降器粗旋工作性能的数值模拟

引言 催化裂化工艺(fluidized catalytic cracking, FCC)是目前我国重质油轻质化加工的主要方法之一.重质油裂化反应过程主要在提升管反应器内完成,提升管出口通常设置旋风分离器(简称粗旋)将反应后油气与催化剂快速分离,以避免发生过裂化反应.粗旋工作性能的优劣直接影响装置目的产物的收率、沉降器内部结焦以及油浆固含量.

Numerical simulation on performances of rough-cut cyclone in FCC disengager

To investigate the performances of rough-cut cyclone in FCC disengager, two-fluid model provided by Fluent 6.2 was used for simulation of the dense phase flow.Agglomeration among particles was calculated by a set of improved gas-solid drag expressions.The results show that separation efficiency of rough-cut cyclone for catalyst reaches 98.48%.The solid concentration influences on the leakage of gases off dipleg are involved in three mechanisms: weakening on the gas swirling motion, dragging forces fundamentally caused by the particle gravitation and the wrapping effects onto the gas.The leakage ratio of the dipleg is 32.17% and it can be reduced to 20.97% by adding a hopper.It is proved that the concentration turning point for pressure drop is a function concerning particle density, viscosity and granular sizes.Pressure drops of rough-cut cyclone calculated by the wall film growth theory have good agreement with numerical simulation results.