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 Ri

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.