Partitioning of a wide bubbling fluidized bed with vertical internals to improve local mixing and bed material circulation Articles uri icon

publication date

  • August 2022

start page

  • 1

end page

  • 13

issue

  • 117771

volume

  • 408

International Standard Serial Number (ISSN)

  • 0032-5910

Electronic International Standard Serial Number (EISSN)

  • 1873-328X

abstract

  • Industrial scale fluidized bed reactors are characterized by limited mixing rates, either local or global, especially when using low-pressure drop gas distributors to reduce operational costs. In this work, partitioning of wide beds using vertical internals is proposed as an effective technique to improve local mixing in large reactors, i.e., mixing in specific zones of the bed. The effect of the vertical internals height on local solids mixing within partitions was experimentally evaluated in a pseudo-2D bed by analyzing the velocity and flow structure of the solids and the circulation time within individual partitions. In the presence of internals, global mixing, i.e., mixing between neighboring partitions and across the entire reactor, may be reduced as vertical internals compartmentalize the bed. Thus, the effect of the internals height on global mixing was also quantified while using bed materials with the same properties, but differing in color, in the different partitions, and analyzing the time evolution of the concentration of solids. Furthermore, the effect of internals on bubbles was also evaluated for different internal heights. It was found that internals with a height between the gulf-stream height and the fixed bed height promote the appearance of vortex pair structures in each partition of the wide bed. These structures substantially improve local mixing within each partition, while global mixing between partitions is practically unaffected by the presence of these short internals.

subjects

  • Chemistry
  • Industrial Engineering
  • Materials science and engineering
  • Mechanical Engineering
  • Physics

keywords

  • bubbling fluidized bed; global mixing; local mixing; vertical internals