Effect of internal tubes on the flow structures in gas-solid fluidized beds

The influence of internal tubes present in the fluidized bed on its hydrodynamic behavior was examined in this study. One tube was completely immersed in the bed of 650 m glass beads at 10 cm above the air distributor in the 15 cm inner diameter fluidized bed column of aspect ratio 1. The pressure fluctuations signal was collected over 300 s and was consequently analyzed by the both statistical and wavelet analyses. The results showed that the presence of tube within the bed suppresses the occurrence of macro-scale phenomena like formation of large bubbles and its stability and supports the meso-structures such smaller bubbles, voids and clusters. It leads to an earlier onset of bubbling flow regime as well as turbulent flow regime. The observed minimum bubbling velocities were compared with data in literature and were found in a good agreement with them.