Open AccessComputational study of particle distribution development in a cold-flow laboratory scale downer reactor
Author(s) -
Tatiana López-Montoya,
C. A. Bustamante,
César Nieto-Londoño,
Natalia Gómez-Velásquez
Publication year - 2021
Publication title -
c.t. and f ciencia, tecnología, futuro/ctandf ciencia, tecnología y tuturo
Language(s) - English
Resource type - Journals
eISSN - 2382-4581
pISSN - 0122-5383
DOI - 10.29047/01225383.172
Subject(s) - mechanics , computational fluid dynamics , fluidized bed combustion , multiphase flow , flow (mathematics) , mixing (physics) , residence time distribution , fluid catalytic cracking , materials science , fluidized bed , fluent , volume fraction , residence time (fluid dynamics) , particle (ecology) , engineering , cracking , waste management , physics , geology , geotechnical engineering , oceanography , quantum mechanics , composite material
The use of downer reactors (gas-solid co-current downward flow) in the Fluid Catalytic cracking (FCC) process for the upgrading of heavy crude oil into more valuable products has gradually become more common in the last decades. This kind of reactor is characterized by having homogeneous axial and radial flow structures, no back mixing, and shorter residence times as compared with the riser reactor type. Although downer reactors were introduced a long time ago, available information in literature about the multiphase hydrodynamic behavior at FCC industrial scale is scarce. Therefore, it is necessary to conduct experimental and computational studies to enhance the understanding of the hydrodynamics of two-phase co-current downward flow. The Computational Fluids Dynamics (CFD) software, Ansys Fluent, is used to study two-dimensional gas (air) and solid (catalyst particle) flow in a downer section of a cold-flow circulation fluidized bed (CFB) system at a laboratory scale. The implemented computational model is validated by comparing numerical results for solid velocity and volume fraction with measurements carried out on a CFB system using a fiber-optic probe laser velocimeter. According to numerical results obtained for different gas velocity and solid flux, flow development cannot only be estimated by considering solid axial velocity changes along the reactor; it is also necessary to take into account solid volume fraction axial variations as radial profiles can change even when velocity profiles are developed.