Effect of baffles on performance of fluid catalytic cracking riser--颗粒学报PARTICUOLOGY

Shah, M. T., Pareek, V. K., Evans, G. M., & Utikar, R. P. (2018). Effect of baffles on performance of fluid catalytic cracking riser. Particuology, 38, 18-30. https://doi.org/10.1016/j.partic.2017.05.012

Effect of baffles on performance of fluid catalytic cracking riser

Milinkumar T. Shah ^a *, Vishnu K. Pareek ^a, Geoffrey M. Evans ^b, Ranjeet P. Utikar ^a

a Department of Chemical Engineering, Curtin University, Western Australia, Australia
b Department of Chemical Engineering, University of Newcastle, New South Wales, Australia

10.1016/j.partic.2017.05.012

Volume 38, June 2018, Pages 18-30

Received 28 October 2016, Revised 16 May 2017, Accepted 25 May 2017, Available online 22 September 2017, Version of Record 2 April 2018.

E-mail: milinkumar.shah@curtin.edu.au; milinkumar.shah@gmail.com

Highlights

• A CFD model of a reactive flow of gas, catalyst and droplets was developed.

• The model was used to investigate effect of baffles on performance of FCC riser.

• Baffles enhanced radial dispersion of catalyst and heat transfer inside the riser.

• Baffles increased conversion of VGO, yield of the gasoline and pressure drop.

• Optimization of baffle configurations was required for desired performance.

Abstract

Increasing demand of automobile fuel and a need to process heavier crude oil makes it imperative to find improvements to the design of existing fluid catalytic cracking (FCC) units. Several modifications to the design of the riser section of FCC units have been suggested in previous studies including: improved feed nozzle designs, multiple nozzle configurations, internal baffles, and novel two-stage-riser systems. In this study, we investigate the effects of baffles on the performance of FCC risers using computational fluid dynamics simulations. In this study, predictions from a basis model (without baffles) are compared with those from four different configurations including: (i) 5-cm baffles at 5-m spacing, (ii) 7.5-cm baffles at 5-m spacing, (iii) 10-cm baffles with 5-m spacing, (iv) 10-cm baffles at 2.5-m spacing, and (v) 10-cm baffles at 1-m spacing. The baffles force the catalyst away from walls toward the center of the riser, enhancing the radial dispersion of the catalyst and the heat transfer inside the riser. The use of longer baffles and smaller spacings further increases the dispersion, yielding more homogeneous radial profiles. The changes in the radial dispersion result in variations in the conversion, yields, and pressure drops. The baffles increase conversion of vacuum gas oil (VGO) and the yield of gasoline. However, the simulations showed that longer baffles and a larger number of baffles did not always give a higher yield or higher conversion. Among the simulated configurations, the 5-cm baffles at 5-m spacing gave the highest conversion of VGO, whereas the 10-cm baffles at 1-m spacing resulted in the highest yield of the gasoline. Thus, rational optimization of baffle configurations is required to achieve optimal performance.

Graphical abstract

Keywords

Fluid catalytic cracking; Riser; Baffles; Computational fluid dynamics

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