(491b) An Open-Source Library for Multi-Step Reactions in Spherical and Cylindrical Particles | AIChE

(491b) An Open-Source Library for Multi-Step Reactions in Spherical and Cylindrical Particles


Wakefield, J. - Presenter, University of Michigan
Lattanzi, A., University of Michigan
Pecha, M. B., National Renewable Energy Lab
Ciesielski, P. N., National Renewable Energy Laboratory
Capecelatro, J., Dept of Mechanical Engineering
In this talk we will introduce a new open-source library for modeling multi-step reactions in porous catalyst particles. Single-step effectiveness factors based on Thiele modulus, while useful, cannot accurately capture the cascading reaction systems that are so common in high temperature vapor-phase chemical reactors like FCC units and catalytic biomass fast pyrolysis systems. Multi-step effectiveness factors were derived analytically from steady-state solutions to the governing reaction-diffusion equations in spherical and cylindrical coordinates by diagonalization. The resulting method consists of a coordinate transform of the boundary conditions, evaluation of single-stage effectiveness coefficients, and a coordinate transform back to concentration. Comparisons are made against particle-resolved direct numerical simulations (DNS) in the single-stage and multi-stage cases. Efficient computation of effectiveness factors depends on carefully balancing pre-processing with online computation; rationale for the division made and alternatives will be presented. The resulting open-source library is designed to be integrated into reactor scale models (e.g., discrete element models, two-fluid models) to accurately predict chemistry using coarse-graining with dramatically less computational cost than DNS or reduced-order sub-grid models.