CFD–DEM modeling of autothermal pyrolysis of corn stover with a coupled particle- and reactor-scale framework

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Vol. 446; no. 2; p. 136920
• Main Authors: Oyedeji, Oluwafemi A., Brennan Pecha, M., Finney, Charles E.A., Peterson, Chad A., Smith, Ryan G., Mills, Zachary G., Gao, Xi, Shahnam, Mehrdad, Rogers, William A., Ciesielski, Peter N., Brown, Robert C., Parks II, James E.
• Format: Journal Article
• Language: English
• Published: United States Elsevier B.V 15.10.2022; Elsevier
• Subjects: Biochar oxidation; Detailed reaction scheme; INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; MFiX; Multi-scale model; Oxidative pyrolysis; Process intensification; Detailed reaction scheme; Multi-scale model; Process intensification; Oxidative pyrolysis; MFiX; Biochar oxidation
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2022.136920

•Autothermal pyrolysis of corn stover was simulated with reactor-scale CFD-DEM coupled with particle resolved data.•The predicted yields of bio-oil, light gas, and biochar from autothermal pyrolysis closely fit experimental data.•The impacts of equivalence ratio, biomass injection position, and particle size distribution were investigated. Autothermal operation of fast pyrolysis is an efficient process-intensification technique wherein exothermic oxidation reactions are used to overcome the heat-transfer bottleneck of conventional pyrolysis. The development of accurate, reliable modeling toolsets is imperative to generating a deeper understanding of biomass autothermal pyrolysis systems to support scale-up and industrial deployment. This modeling effort describes the development of single-particle and reactor models which incorporate detailed reaction schemes and simultaneous exothermic oxidation reactions. The particle-scale model was parameterized for corn stover feedstock with particle morphology, density, ash content, and biopolymer composition, all of which impact the emergent conversion characteristics during pyrolysis. Results were then used to parameterize a reactor-scale autothermal pyrolysis model, which was developed using a coarse-grained computational fluid dynamic–discrete element method. The simulation results compared well with experimental results, with the predicted bio-oil, light gas, and biochar yield within 3.0 wt% of the experimental yields. Further analyses were performed to test the influence of equivalence ratio, biomass injection position, and particle size distribution on autothermal pyrolysis. The analysis of the physio-chemical properties of the fluid and solid phase inside the reactor and at the reactor outlet help reveal important process interactions of autothermal pyrolysis.