FCC沉降器内流体的流动特性与停留时间分布  

Flow Characteristics and Residence Time Distribution in an FCC Disengager

作　　者：王江云[1] 毛羽[1] 王娟[1] 

机构地区：[1]中国石油大学(北京)重质油加工国家重点实验室,北京102249

出　　处：《过程工程学报》2009年第S2期185-189,共5页The Chinese Journal of Process Engineering

基　　金：国家973计划资助项目(编号:2004CB217803)

摘　　要：采用RNGk-ε湍流模型、随机轨道模型和欧拉-欧拉多相流模型对一种粗旋排气管带有导流结构的FCC沉降器内的流动状况进行了全尺寸的数值模拟,得到了沉降器所有空间内油气和催化剂的流动细节.研究发现,约90%的油气从粗旋分离器排气管排出进入沉降器空间,其余的油气随粗旋料腿排出的催化剂进入了密相;沉降器空间内油气流速非常缓慢,部分油气冷凝为液滴和催化剂在器壁上黏附并累积,进而脱氢缩合生成焦炭导致大量结焦,对催化裂化的安全长周期运行造成隐患;随着导流段长度的增加,粗旋排出直接进入顶旋的油气量也随之增加,当导流段长度L=0.95de时,约有83%的油气直接进入顶旋,此时油气在沉降器空间内的平均停留时间较常规沉降器缩短约2/3.A full-size numerical simulation of the flow in FCC disengager with diversion section was carried out by applying RNG k-ε model,stochastic tracking model and Eulerian-Eulerian multiphase model.All details of oil gas and catalyst in the flow domain were obtained.It was shown that 90% of oil gas discharged from primary cyclone separator entered the disengagement space,while others flowed into dense phase along with catalyst discharged from diplegs of primary cyclone separators.The oil gas must experience longer residence time due to the lowest velocities in the disengagement space.Some liquid droplets condensed from heavy fractions of FCC products and catalyst attached and deposited on the wall and then was involved in the condensation reactions to form coke,leading to the risk of unscheduled shut-downs of FCC with consequent adverse effects on their long term operation.With the growth of the diversion section length the percentage of gas oil directed into the inlets of the secondary cyclones also increased.When diversion section length L=0.95de,the percentage of the oil gas directed into the inlets of the secondary cyclone separators was about 83%,while the average residence time of oil gas in the disengagement space was decreased by two thirds.

关 键 词：FCC沉降器 结焦 流动 欧拉模型 数值模拟 停留时间 

分 类 号：TE624.41[石油与天然气工程—油气加工工程]