Investigating hydrodynamics and gas diffusion coefficient in CFB of binary particles with significant differences in particle properties

•The high-density cluster was effectively inhibited and heavy particles were distributed more uniformly.•The radial gas diffusion was accelerated and the mixing was enhanced in SCFB.•Gas-solid flow in SCFB was closely to the mixed-type flow. A composite fluidized bed (SCFB), which integrated the bub...

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Bibliographic Details
Published in:	Chemical engineering and processing Vol. 203; p. 109903
Main Authors:	Chen, Hengzhi, Mu, Changan, Ding, Yuxuan
Format:	Journal Article
Language:	English
Published:	Elsevier B.V 01-09-2024
Subjects:	Fluidized bed Gas diffusion coefficient Semi-circulating fluidization technique Wavelet transform Semi-circulating fluidization technique Wavelet transform Gas diffusion coefficient Fluidized bed
Online Access:	Get full text
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Summary:	•The high-density cluster was effectively inhibited and heavy particles were distributed more uniformly.•The radial gas diffusion was accelerated and the mixing was enhanced in SCFB.•Gas-solid flow in SCFB was closely to the mixed-type flow. A composite fluidized bed (SCFB), which integrated the bubbling fluidization and circulating fluidization into one bed, was developed in this work. Wavelet transform was employed to analyze time-series signals of the pressure fluctuations and the steady-state tracer injection technique was used to study the gas diffusion coefficient in SCFB. The energy contribution in BFB and CFB mainly concentrated on the macrostructures, while that in SCFB was caused principally by the mesostructures as gas velocity was high. The circulating particles could effectively reduce particle aggregates and promoted a uniform distribution of heavy particles in the bottom region. Radial dispersion coefficients in SCFB were greater than that in BFB and CFB, demonstrating that the circulating particles enhanced gas mixing in SCFB. The ratio of Da/Dr in SCFB was less than that in BFB, indicating that gas-solid flow in SCFB was more closely to the mixed-type flow compared to the BFB. [Display omitted]
ISSN:	0255-2701
DOI:	10.1016/j.cep.2024.109903