As a high-performance material with great application potential

the application of carbon nanotubes has been limited by their production volume. A distributor-less conical fluidized bed is the main equipment used in the industrial production of carbon nanotubes. To improve the production volume and product quality of carbon nanotubes

the study of fluidized-bed-diameter scaling is important. Three different diameters of distributor-less conical fluidized beds were established

and then the particle behavior and bubble characteristics of carbon nanotube clusters at these bed diameters were investigated. Time-series and wavelet analysis methods were used to analyze the pressure-fluctuation signals inside the fluidized beds. Results showed that the distributor-less design caused the airflow to break through the middle of the bed

which did not change with the change in bed diameter. The powder-bridging phenomenon of carbon nanotube clusters in a 100-mm-diameter fluidized bed was related to the special microstructure of carbon nanotube clusters. The frequency of pressure fluctuations in the bed decreased nonlinearly with increasing bed diameter. This study can guide the design and scale-up of distributor-less conical fluidized beds

especially for the scale-up of carbon nanotube production equipment

which can contribute to the improvement of carbon nanotubes’ capacity and quality in industrial production.