Abstract:

A large-scale cold model experimental setup of a riser-fluidized bed coupled reactor was established according to olefin reduction technology with auxiliary reactor for FCC naphtha upgrading.The particle flow behavior in the outlet region of the riser section was experimentally investigated in the setup.Furthermore, the restriction index R_i, the ratio between real and theoretical averaged cross-sectional solid holdups in the particle back-mixing region section, was defined to quantitatively show the restriction effect of the riser outlet distributor and upper fluidized bed on the particle flow behavior in this region.The experimental results showed that, compared with the conventional riser, there existed a particle back-mixing region in the riser outlet of the coupled reactor.The length of the particle back-mixing region was related to the superficial gas velocity, solids flux and the solids bed level in the upper fluidized bed.The maximum local solids holdup in the particle back-mixing region close to the riser outlet appeared at the non-dimensional radial position Φ=0.7 at a lower superficial gas velocity and a higher solids flux. This was because an inverted taper gas-solid distributor was mounted at the riser outlet.The restriction index tended to increase with the axial position increasingly close to the riser outlet.At the same time, the restriction effect of the gas-solid distributor and upper fluidized bed on the gas-solid flow behavior was also gradually enhanced.

Key words:

耦合反应器, 提升管, 约束返混区, 流动特性, 约束指数

摘要：

针对催化汽油辅助反应器改质降烯烃工艺，在一套提升管-流化床耦合反应器大型冷态实验装置上，系统研究了提升管出口段的颗粒流动特性，通过定义约束指数R_i（R_i为颗粒约束返混区实际截面平均固含率与理论截面平均固含率之比）定量反映提升管出口分布器及流化床层的约束作用。结果表明，与常规提升管相比，耦合反应器提升管出口存在一个颗粒约束返混区，其长度主要受表观气速、颗粒循环强度及上部流化床内颗粒静床高度影响;由于出口设置了倒锥形分布器，使得颗粒约束返混区靠近提升管出口区域在表观气速较低和颗粒循环强度较大时，局部固含率最大值出现在量纲 1半径Φ＝0.7处;颗粒约束返混区的约束指数在靠近出口的过程中逐渐增大，气固流动受到分布器及上部流化床层的约束作用亦逐渐增强。

关键词:

耦合反应器, 提升管, 约束返混区, 流动特性, 约束指数