RT Journal Article
T1 Extension of the layer particle model for volumetric conversion reactions during char gasification
A1 Steiner, Thomas
A1 Schulze, Kai
A1 Scharler, Robert
A1 Anca Couce, Andres
AB The so-called 'layer model' or 'interface-based model' is a simplified single particle model, originally developed for shorter computation time during computational fluid dynamics (CFD) simulations. A reactive biomass particle is assumed to consist of successive layers, in which drying, pyrolysis and char conversion occur sequentially. The interfaces between these layers are the reaction fronts. The model has already been validated for drying, pyrolysis and char oxidation. Layer models in the literature have commonly employed surface reactions at the reaction front to describe char conversion. In this work, the suitability of this surface reaction concept is assessed when gasifying biochar. It is shown that a particular layer model, already available, which originally employed surface reactions, was unable to adequately describe the mass loss during gasification of a biochar. In order to overcome this incapability, the model was extended to consider volumetric reactions in the char layer. The influence of intraparticle diffusion was considered through an effectiveness factor. The model is easily adaptable for different gas-solid kinetic rate laws, while still allowing for comparably fast solutions of the model equations. The extended model was validated using theoretical calculations and experimental measurements from literature. It was demonstrated that intraparticle diffusion can significantly slow down the biochar gasification process. A general guideline for when to employ volumetric reactions, rather than surface reactions, and when to consider intraparticle diffusion is provided based on the Thiele modulus as the criterion.
PB Elsevier
SN 0010-2180
YR 2023
FD 2023-10-01
LK https://hdl.handle.net/10016/39260
UL https://hdl.handle.net/10016/39260
LA eng
NO Acknowledgments. The COMET Module BIO-LOOP (Austrian Research Promotion Agency Project Number 872189) is funded within COMET - Competence Centers for Excellent Technologies - by the Federal Ministry for Climate Action, Environment, Energy, Mobility, Innovation and Technology and the Federal Ministry for Digital and Economic Affairs as well as the co-financing federal province Styria. The COMET programme is managed by FFG (Austrian Research Promotion Agency, www.ffg.at/comet). The funding is gratefully acknowledged.
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RD 30 jun. 2024