Influence of air bubble size on float-sink of spheres in a gas-solid fluidized bed

Jun Oshitani, Yuhei Isei, Mikio Yoshida, Kuniaki Gotoh, George V. Franks

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

The float-sink of density adjusted spheres of different diameter (10-40 mm) in a gas-solid fluidized bed was investigated at various bed heights (50-200 mm). The maximum density of floating spheres (ρ float) and the minimum density of sinking spheres (ρ sink) were determined by the float-sink experiments. The fluidized bed density (ρ fb) was measured using the height and cross section of the fluidized bed and total weight of the fluidized media. The diameter of air bubbles at the bed surface was measured at each bed height, and was normalized by the sphere diameter. It was found that the value of ρ fbfloat approaches zero as the normalized bubble diameter decreases from 4 to 0.5 regardless of the sphere diameter. The value of ρ sinkfb for sphere diameter = 10 mm approaches zero as the normalized bubble diameter decreases from 4 to 1.5, whereas the value for sphere diameter = 20-40 mm rises from zero as the normalized bubble diameter decreases from 1.5 to 0.5. The float and sink of spheres basically tend to follow the fluidized bed density with decreasing the normalized bubble diameter. However, relatively larger spheres do not sink based on the density difference as the normalized bubble diameter decreases, which may be due to that the fluidized bed viscosity becomes larger as the normalized bed diameter decreases.

Original languageEnglish
Pages (from-to)120-123
Number of pages4
JournalAdvanced Powder Technology
Volume23
Issue number1
DOIs
Publication statusPublished - Jan 2012

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Keywords

  • Air bubble size
  • Bed height
  • Dry separation
  • Fluidized bed

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Mechanics of Materials

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