Multiscale Modeling of a Packed Bed Chemical Looping Reforming (PBCLR) Reactor

Arpit Singhal,Shahriar Amini,Rosa Quinta-Ferreira,Schalk Cloete

doi:10.3390/en10122056

Arpit Singhal, Shahriar Amini + Show 2 more

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https://doi.org/10.3390/en10122056

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Abstract

Packed bed reactors are broadly used in industry and are under consideration for novel reactor concepts such as packed bed chemical looping reforming (PBCLR). Mass and heat transfer limitations in and around the particles in packed bed reactors strongly affect the behavior of these units. This study employs a multiscale modeling methodology to simulate a PBCLR reactor. Specifically, small-scale particle-resolved direct numerical simulation is utilized to improve large-scale mass transfer models for use in an industrial scale 1D model. Existing intra-particle mass transfer models perform well for simple first order reactions, but several model enhancements were required to model the more complex steam methane reforming reaction system. Three specific aspects required enhanced modeling: the generation of additional gas volume by the reforming reactions, the lack of clear reaction orders in the equilibrium reactions, and the diffusion of multiple reactant species into the particle. Large-scale simulations of the PBCLR reactor with the enhanced 1D model showed that the highly reactive Ni-based catalyst/oxygen carrier employed allows for the use of large particle sizes and high gas flowrates, offering potential for process intensification.

Highlights

Packed beds are broadly deployed in the chemical and process industry, with a wide variety of uses in adsorption, heat exchangers, chemical reforming, etc
The geometry is meshed with polyhedral elements using FLUENT Meshing both inside and outside the particles with a cell size of dp /30 on the particle surfaces
A growth rate of 20% is used to propagate the mesh into the domain

Summary

Introduction

Packed beds are broadly deployed in the chemical and process industry, with a wide variety of uses in adsorption, heat exchangers, chemical reforming, etc. Gas–solid reaction systems in packed beds can be classified under heterogeneous catalytic and/or non-catalytic reactions. Packed beds generally use relatively large particles to minimize pressure drop over the reactor. These large particles result in significant mass and heat transfer limitations affecting the reactor performance. Significant research efforts have been invested over several decades to correctly model these limitations in catalytic and non-catalytic reactions, the latter being more complex as the solid is altered in the reactions [1]. With the development in the field of computational resources, it is possible to obtain resolved

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