An experimental and numerical study of the suppression of jets, counterflow, and backflow in vortex units

Shekhar R. Kulkarni, Arturo Gonzalez-Quiroga, Manuel Nuñez, Cedric Schuerewegen, Patrice Perreault, Chitrakshi Goel, Geraldine J. Heynderickx, Kevin M. Van Geem*, Guy B. Marin

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

Vortex units are commonly considered for various single and multiphase applications due to their process intensification capabilities. The transition from gas-only flow to gas–solid flow remains largely unexplored nonetheless. During this transition, primary flow phenomenon, jets, and secondary flow phenomena, counterflow and backflow, are substantially reduced, before a rotating solids bed is established. This transitional flow regime is referred to as the vortex suppression regime. In the present work, this flow transition is identified and validated through experimental and computational studies in two vortex units with a scale differing by a factor of 2, using spherical aluminum and alumina particles. This experimental data supports the proposed theoretical particle monolayer solids loading that allows estimation of vortex suppression regime solids capacity for any vortex unit. It is shown that the vortex suppression regime is established at a solids loading theoretically corresponding to a monolayer being formed in the unit for 1g-Geldart D- and 1g-Geldart B-type particles. The model closely agrees with experimental vortex suppression range for both aluminum and alumina particles. The model, as well as the experimental data, shows that the flow suppression regime depends on unit dimensions, particle diameter, and particle density but is independent of gas flow rate. This combined study, based on experimental and computational data and on a theoretical model, reveals the vortex suppression to be one of the basic operational parameters to study flow in a vortex unit and that a simple monolayer model allows to estimate the needed solids loading for any vortex device to induce this flow transition.

Original languageEnglish (US)
Article numbere16614
JournalAIChE Journal
Volume65
Issue number8
DOIs
StatePublished - Aug 2019

Bibliographical note

Funding Information:
H2020 European Research Council, Grant/ Award Number: FP7/2007-2013; Institute for Promotion of Innovation through Science and Technology in Fladers (IWT), Grant/Award Number: IWT-SBO 130039; Flemish Government; Hercules Foundation; Seventh Framework Programme; European Union

Funding Information:
The SBO project ?Bioleum? (IWT-SBO 130039) supported by the Institute for Promotion of Innovation through Science and Technology in Flanders (IWT) is acknowledged. The research leading to these results has received funding from the European Research Council under the European Union's Seventh Framework Programme (FP7/2007-2013)/ERC grant agreement n? 290793. The computational resources and services used in this work were provided by the VSC (Flemish Supercomputer Center), funded by the Hercules Foundation and the Flemish Government ? department EWI. Dr. Vladimir Shtern is acknowledged for discussions on single and multiphase flow in vortex units. Notation Vs solid volume in unit (m3) ms solid mass in unit (kg) mp single particles mass (kg) Vmonolayer solid monolayer volume (m3) Rr (Dr) unit radius (diameter) (m) De exhaust diameter (m) dp particle diameter (m) H unit length (m) L bed height (m) Np number of particles (?) v velocity (m s?1) IN number of slots (?) I0 slot width (m) ess restitution coefficient (?) Q gas flow rate (Nm3 h?1) g acceleration due to gravity (m s?2) S swirl Ratio [?] S?=2?Rrcos?INI0 P pressure (kPa) z axial direction (?) r radial direction (?) usup superficial velocity (m s?1) usup?=Q2?RrH ? specularity coefficient (?) Rep particle Reynolds Number: Rep?=?sdpusup?g Stp particle Stokes number: Stp?=?sdp2vg18?gHS (?) ? viscosity (Pa s) ? volume fraction (?) ? density (kg m?3) ? angular coordinate (?) ? slot angle (?) Subscripts g gas phase s solid phase inj slot injection ex exhaust

Funding Information:
The SBO project “Bioleum” (IWT-SBO 130039) supported by the Institute for Promotion of Innovation through Science and Technology in Flanders (IWT) is acknowledged. The research leading to these results has received funding from the European Research Council under the European Union's Seventh Framework Programme (FP7/2007-2013)/ERC grant agreement n° 290793. The computational resources and services used in this work were provided by the VSC (Flemish Supercomputer Center), funded by the Hercules Foundation and the Flemish Government – department EWI. Dr. Vladimir Shtern is acknowledged for discussions on single and multiphase flow in vortex units.

Publisher Copyright:
© 2019 American Institute of Chemical Engineers

Keywords

  • gas–solid vortex reactor
  • gas–solid vortex units
  • monolayer model
  • process intensification
  • vortex suppression regime

ASJC Scopus subject areas

  • Biotechnology
  • Environmental Engineering
  • General Chemical Engineering

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