The minimum fluidization velocity and dynamic characteristics of agglomerated carbon nanotube in a tapered fluidized bed at elevated temperature

• Published in: Chemical engineering research & design Vol. 168; pp. 239 - 253
• Main Authors: Bai, Wenjuan, Chu, Dianming, He, Yan
• Format: Journal Article
• Language: English
• Published: Rugby Elsevier Ltd 01.04.2021; Elsevier Science Ltd
• Subjects: Agglomeration; Carbon; Carbon nanotubes; Distributors; Dynamic characteristics; Elevated temperature; Energy distribution; Fixed beds; Fluidized bed reactors; Fluidized beds; Heat transfer; High temperature; Minimum fluidization velocity; Multi-Wall carbon nanotube (MWCNT); Nanotubes; Tapered fluidized bed (TFB); Temperature; Temperature effects; Time series; Wavelet analysis; Wavelet analysis; Elevated temperature; Tapered fluidized bed (TFB); Multi-Wall carbon nanotube (MWCNT); Minimum fluidization velocity
• ISSN: 0263-8762; 1744-3563
• DOI: 10.1016/j.cherd.2021.02.014

•The Umf decreased for both types of particles with the increase of the temperature.•The mesoscale signals dominated flow behaviors in the TFB without a distributor.•The inhomogeneous fluidization characteristics were existed in the bed at elevated temperature. In this work, the fluidization characteristics of gas–agglomerated carbon nanotube (CNT) particles flow in a tapered fluidized bed (TFB) without a distributor were investigated between 180 and 680 °C for the first time. The objective of this work was to investigate the effect of temperature on minimum fluidization velocity (Umf) and dynamic characteristics of gas–agglomerated CNT particles flow at elevated temperature. To this end, the experimental work was divided into two phases. In the first phase, the influence of temperature on the Umf and the correlations of Umf for agglomerated CNT particles at different bed temperatures were investigated and obtained. In the second phase, the dynamic characteristics of gas-agglomerated CNT particles flow in the TFB without a distributor at elevated temperature were studied in detail via time-series analysis methods. Experimental results revealed that the Umf decreased for agglomerated CNT particles with the increase of temperature, and the correlations could be reasonable predicted the Umf over the range of variables investigated. The inhomogeneous dynamic characteristics were existed in the bed at elevated temperature in the meso-scale due to the stochastic features of small bubbles or cavities movement. Moreover, though the time-series parameters (standard deviation, wavelet energy distribution, and homogeneous index) of the dynamic characteristics were different, the gas- agglomerated CNT particles flow behaviors under different operating conditions showed a high sensitivity to the temperature from the fixed bed to the partial fluidization regime.