Computational fluid dynamics (CFD) has been widely used in both scientific studies and industrial applications of reactor-scale biomass pyrolysis. In this Perspective, the state-of-the-art progress in CFD modeling of reactor-scale biomass pyrolysis was summarized and discussed. First, because of the importance of biomass pyrolysis reaction kinetics to the predictability of CFD, the commonly used pyrolysis reaction kinetics in CFD modeling of reactor-scale biomass pyrolysis were reviewed. The characteristics of each reaction kinetics were described. Then, the theoretical basis and practical applications of three main CFD modeling approaches, i.e., porous media model, multifluid model, and discrete particle model for simulating reactor-scale biomass pyrolysis were presented. The activities and progresses with respect to each CFD modeling approach for reactor-scale biomass pyrolysis were reviewed. Aspects such as experimental validation, modeling speed, and capability were discussed. Finally, the paper was concluded with comments on future directions in CFD modeling of reactor-scale biomass pyrolysis.

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To accurately characterize biomass fast pyrolysis at the particle scale, intra-particle transport phenomena needs to be considered together with the gas flow surrounding the particle. In this study, a detailed numerical method was used to simulate the evolution of biomass particles under fast pyrolysis conditions. To conduct particle-scale simulations, the lattice Boltzmann method (LBM) was employed to solve the conservation equations, and pyrolysis kinetics were implemented to describe the chemical reactions. The present model was validated by comparing the numerical results with experimental data for a single biomass particle under pyrolysis conditions. The predicted temperature and conversion history agree with the experimental data. The temperature and density fields in the particle were found to be anisotropic due to the effect of the gas flow surrounding the particle, which was ignored by the 1D model. The non-uniform distributions of surface temperature indicate that using a constant temperature or heat flux as boundary conditions may cause numerical errors. Sensitivity analysis shows that density is the most influential parameter while porosity is the least. The heat of reaction converting the intermediate solid to char is more dominant than those of the three primary reactions. A parametric study was conducted to investigate the effect of particle shape on conversion time and final product yields. The simulation results show that the conversion time decreased when using the elliptic particle instead of the regular (circular) particle. The model