Investigation of particle flow behaviors in a simplified downcomer of multistage fluidized bed

This work investigated the particle flow behaviors in the orifice downcomer of the multistage fluidized bed based on a simplified experimental device, in which the flow behavior can be observed conveniently and directly. Three flow patterns were observed, which were the stable moving bed, the bubbling moving bed, and the slugging bed. Furthermore, significant differences were found in the pressure pulsation signals of different flow patterns, thus a flow pattern identification method using pressure pulsation spectrum was proposed and the corresponding flow pattern maps were established for the orifice downcomer with different diameters. Finally, the difference between the stable moving bed and the bubbling moving bed was further studied. Results showed that the solid flow rate in the sable moving bed state was related to the superficial gas velocity in the downcomer, while it was only related to the cavity appearing near the orifice in the bubbling moving bed state.