Abstract: The axial and radial distributions of the local particle velocities at different radial positions on various axial levels along the downer-column were measured by using a PV-4A fiber-optic particle velocity probe in a half-column downer of 2m high and 30mm I.D.,and the effects of operation conditions and spouted positions on the local particle velocities were also investigated in this paper. Then the radial particle velocity distributions of binary particle mixture，formed by respectively and simultaneously injecting fine-FCC catalysts and coarse-glass beads in downers，were examined at different composition ratios of FCC catalysts to glass beads. Finally, based on the concept of dimensionless local particle velocities the new correlations for predicting the local particle velocity distributions of FCC catalysts and glass beads were developed by regressing experimental data from literatures and this study. Results show that the radial distributions of local particle velocities vary significantly with the particle properties, and for binary particle mixture, the radial distributions are more uniform as compared with those of only FCC catalysts and the double-peaked distribution characteristics of particle velocity profiles become more obvious with the increase of superficial gas velocities, since in this case fine particles mixed by injecting coarse particles will result in the variation of gas-solids dynamic mechanism and the smoothness of particle velocity distributions in dowers.

摘要： 采用PV-4A光导纤维测速仪在一高2m、直径30mm的下行床反应器中较系统地测定了FCC催化剂及玻璃珠各自在6个截面8个不同径向位置局部颗粒速度的轴向及径向分布，研究了操作条件及喷口位置对该两种不同物料局部颗粒速度径向分布的影响，进而将FCC催化剂和玻璃珠两种物料分别同时进入下行床反应器中，考察了以不同混合比组成的二元组分混合物的颗粒速度径向双峰分布特点.最后，分别给出了预测FCC催化剂及玻璃珠的量纲1局部颗粒速度经验关联式.实验结果表明：物性不同的粒子其局部颗粒速度径向分布差别较大，二元组分混合物的颗粒速度径向分布较FCC催化剂单一颗粒趋于均匀，且随表观气速增加，颗粒速度分布双峰特性愈为明显，可见在下行床进入细颗粒的同时加入粗颗粒引起了气固流动机制的变化与颗粒速度分布的平滑.