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Multi-distributed activation energy model for wood pyrolysis : modelling strategy applied to experimental kinetics of different particle sizes

Abstract : Pyrolysis of lignocellulosic biomass is an effective method for the bio-liquid and syngas productions. The multi-distributed activation energy model (DAEM) is a comprehensive tool for modelling pyrolysis kinetics. Yet, its optimal strategy regarding distribution number and shape is still an open question. Meanwhile, further developments are needed to extend the model’s ability to predict the effect of particle size. This work aims to establish a robust and universal DAEM strategy for pyrolysis modelling, which is applied to the pyrolysis kinetics of different particle sizes.To assess the models, a validation database was systematically employed after identification on the learning database. A trade-off strategy was defined by testing multi-distribution DAEMs with various distribution number and shape. Three-distribution with relevant shapes ensured good prediction with suitable conciseness, and the combination of two-Gaussian plus one exponential distributions further gave the best trade-off between prediction capacity and numerical complexity. This model showed superiority compared to other DAEMs, first-order and nth-order schemes, being determined as the optimal numerical tool in this work.Afterward, two Gaussian + one exponential DAEM distributions were employed to determine intrinsic parameters for spruce and poplar powder. The quality of kinetics prediction allowed, for the first time, the enthalpies of reaction to be also determined from the DSC signals. Experimental analyses of multi-scale samples revealed the effects of particle size with carbonization enhancements, being further evidenced by the negative correlation between mass loss and elemental compositions. The DAEM identifications provided solid kinetic parameters for different sizes, from which devolatilization profiles and synthetic indices are extracted to show the effect of size on three pseudo-components. The prediction ability of the model was checked by further experiments performed at different time-temperature patterns with several particle sizes. Finally, correlations between dimensionless residual mass (DRM) and element compositions allowed us to determine the composition of secondary charring, which consists mainly of carbon. The elemental composition of char can therefore be predicted using the difference of kinetics between fine powder and a given particle size.
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Submitted on : Tuesday, June 8, 2021 - 4:51:25 PM
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  • HAL Id : tel-03254294, version 1

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Yong Tian. Multi-distributed activation energy model for wood pyrolysis : modelling strategy applied to experimental kinetics of different particle sizes. Chemical and Process Engineering. Université Paris-Saclay, 2021. English. ⟨NNT : 2021UPAST033⟩. ⟨tel-03254294⟩

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