Hydrodynamics and gas mixing in a carbon nanotube agglomerate fluidized bed

Abstract

AbstractA typical nanoscale fiber material, carbon nanotubes (CNTs), was fluidized in a 280 mm inner diameter (ID) nano‐agglomerate fluidized bed (NAFB). The solids distribution and gas mixing were measured by a self‐developed conductance method and the hydrogen tracer technique. Typical nano‐agglomerate fluidization characteristics, such as high bed expansion ratio and multi‐staged agglomerate structure, were observed. Fluidization experiments over a wide gas velocity range showed that the CNT agglomerates have agglomerate‐bubbling‐fluidization (ABF) characteristics. Particulate fluidization can also be achieved in the range 0.017∼0.038 m/s, showing they also have Geldart‐A particle characteristics. A systematic comparison of the transition velocities, solids distributions, and gas mixing between the fluidizations of CNT agglomerates and Geldart‐A particles was carried out. CNT NAFBs have more non‐uniform solids concentration profiles near the wall, but more homogenous micro‐flow structures than Geldart‐A particles, which leads to good gas mixing. These unique hydrodynamics behaviors are attributed to the difference in the microstructure between the nano‐agglomerates and ordinary particles. © 2006 American Institute of Chemical Engineers AIChE J, 2006