Estimation of agglomerate size of multi-walled carbon nanotubes in gas-solid fluidized beds

The hydrodynamic characteristics of multi-walled carbon nanotube agglomerates were investigated using the bed collapse technique and their agglomerate size was determined using the sedimentation method. The bed collapsing process of multi-walled carbon nanotube agglomerates was closer to the Geldart group C particles than to the group A particles. The median diameters of the Multiwall Carbon Nanotubes (MWCNT) agglomerates, determined by sedimentation at an initial superficial gas velocity of 0.120 and 0.190 m/s, were 157 and 221 μm, respectively. The size of the multi-walled carbon nanotube agglomerates in the fluidization state was measured by image analysis using a high speed camera. The median diameter of the multi-walled carbon nanotube agglomerates in the freeboard was increased from 138 to 189 μm as the superficial gas velocity increased from 0.088 to 0.190 m/s at a static bed height of 0.16 m. The median diameter and size distribution determined from the sedimentation fitted well with those measured using image analysis. In this study, the results were reasonable up to a superficial gas velocity of 0.190 m/s.