Gas-solids flow behavior: CFB riser vs. downer

H. Zhang, W. X. Huang, J. X. Zhu

Research output: Journal PublicationArticlepeer-review

74 Citations (Scopus)

Abstract

Comparisons are made in a circulating fluidized-bed riser/downer system between a 15.1 m high, 0.10 m ID riser and a 9.3 m high, 0.10 m ID downer, based on the measurements of the radial distributions of the local solids holdups and local particle velocities along the two columns. Although the core-annulus flow structures exist in both the riser and downer, the radial flow structure in the downer differs largely from that in the riser. The radial distributions of solids holdup and particle velocity in the downer are much more uniform than those in the riser, thus ensuring the low back mixing and the narrow particle residence time distribution in the downer. The axial flow structure in the downer is also more uniform than that in the riser. Due to the high particle acceleration and the high particle velocity in the downer, the overall solids holdup is significantly lower than that in the riser. The microflow structure in the downer, characterized by the low intermittency indices, is also more uniform than that in the riser. These key properties of the downer make it a very promising candidate for industrial applications where short reaction times and high product selectivity are required.

Original languageEnglish
Pages (from-to)2000-2011
Number of pages12
JournalAICHE Journal
Volume47
Issue number9
DOIs
Publication statusPublished - Sep 2001
Externally publishedYes

ASJC Scopus subject areas

  • Biotechnology
  • Environmental Engineering
  • Chemical Engineering (all)

Fingerprint

Dive into the research topics of 'Gas-solids flow behavior: CFB riser vs. downer'. Together they form a unique fingerprint.

Cite this