Issue 5, 2020, Issue in Progress

Scaling of a catalytic cracking fluidized bed downer reactor based on computational fluid dynamics simulations

Abstract

Circulating fluidized bed downer reactors (downer reactors) exhibit good heat and mass transfer, and the flow behavior approaches the ideal plug flow. This reactor is superior for catalytic cracking reactions in which the intermediate is the desired product. However, the hydrodynamic behavior and reactor performance have mostly been investigated in small-scale or laboratory-scale reactors. The objective of this study was to investigate the up-scaling of the catalytic cracking of heavy oil in three downer reactors with heights of 5, 15, and 30 m, using computational fluid dynamics simulations. A two-fluid model with the kinetic theory of granular flow was used to predict the hydrodynamics and performance of the chemical reactions. The kinetics of catalytic cracking of heavy oil were described by a 4-lump kinetic model. The chemical performance similarity was identified by using radial and axial distributions of heavy oil conversion, gasoline mass fraction, and gasoline selectivity. The chemical performance similarity cannot be achieved by using the hydrodynamic similarity parameter Image ID:c9ra10080f-t1.gif. A modified up-scaling parameter was proposed, Image ID:c9ra10080f-t2.gif. The chemical performance similarity of identical catalytic cracking downer reactors can be achieved with deviation in the range of ±10% and mean relative absolute error of less than 5%.

Graphical abstract: Scaling of a catalytic cracking fluidized bed downer reactor based on computational fluid dynamics simulations

Article information

Article type
Paper
Submitted
02 Dec 2019
Accepted
08 Jan 2020
First published
16 Jan 2020
This article is Open Access
Creative Commons BY-NC license

RSC Adv., 2020,10, 2897-2914

Scaling of a catalytic cracking fluidized bed downer reactor based on computational fluid dynamics simulations

P. Khongprom, S. Ratchasombat, W. Wanchan, P. Bumphenkiattikul and S. Limtrakul, RSC Adv., 2020, 10, 2897 DOI: 10.1039/C9RA10080F

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