CFD simulation of gas–solid flow patterns in a downscaled combustor-style FCC regenerator--颗粒学报PARTICUOLOGY

Azarnivand, A., Behjat, Y., & Safekordi, A. A. (2018). CFD simulation of gas–solid flow patterns in a downscaled combustor-style FCC regenerator. Particuology, 39, 96-108. https://doi.org/10.1016/j.partic.2017.10.009

CFD simulation of gas–solid flow patterns in a downscaled combustor-style FCC regenerator

Abbas Azarnivand ^a, Yaghoub Behjat ^b *, Ali Akbar Safekordi ^a

a Department of Chemical and Petroleum Engineering, Sharif University of Technology, Tehran, Iran
b Process Development and Equipment Technology Division, Research Institute of Petroleum Industry, Tehran, Iran

10.1016/j.partic.2017.10.009

Volume 39, August 2018, Pages 96-108

Received 23 July 2017, Revised 4 October 2017, Accepted 17 October 2017, Available online 9 February 2018, Version of Record 17 May 2018.

E-mail: behjaty@ripi.ir

Highlights

• A lab-scale combustor-style regenerator was designed by scaling-down an industrial regenerator.

• The gas–solid flow pattern within the regenerator was scrutinized using CFD simulations.

• Effects of recirculated catalyst, superficial air velocity and catalyst mass flux were studied.

Abstract

To investigate the gas–solid flow pattern of a combustor-style fluid catalytic cracking regenerator, a laboratory-scale regenerator was designed. In scaling down from an actual regenerator, large-diameter hydrodynamic effects were taken into consideration. These considerations are the novelties of the present study. Applying the Eulerian–Eulerian approach, a three-dimensional computational fluid dynamics (CFD) model of the regenerator was developed. Using this model, various aspects of the hydrodynamic behavior that are potentially effective in catalyst regeneration were investigated. The CFD simulation results show that at various sections the gas–solid flow patterns exhibit different behavior because of the asymmetric location of the catalyst inlets and the lift outlets. The ratio of the recirculated catalyst to spent catalyst determines the quality of the spent and recirculated catalyst mixing and distribution because the location and quality of vortices change in the lower part of the combustor. The simulation results show that recirculated catalyst considerably reduces the air bypass that disperses the catalyst particles widely over the cross section. Decreasing the velocity of superficial air produces a complex flow pattern whereas the variation in catalyst mass flux does not alter the flow pattern significantly as the flow is dilute.

Graphical abstract

Keywords

Fluid catalytic cracking; Combustor-style regenerator; Large-diameter fluidized bed; Hydrodynamics; Gas–solid flow pattern; Recirculated catalyst

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