(491b) An Open-Source Library for Multi-Step Reactions in Spherical and Cylindrical Particles
AIChE Annual Meeting
Wednesday, November 10, 2021 - 12:55pm to 1:20pm
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.