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Article Dans Une Revue Journal of Analytical and Applied Pyrolysis Année : 2023

Modelling of lignite pyrolysis using a finite rate chemistry approach: comparison between parallel and competitive chemical schemes

Résumé

Thermal decomposition of lignite under nitrogen atmosphere is studied by using Thermogravimetric analysis (TGA), from room temperature to 1173 K at 10 K/min that is assumed as a sufficiently low heating rate to ensure reactions separation. Four rationally based kinetic schemes are proposed in order to point out the level of complexity needed to be included in the kinetic model to correctly capture the chemistry of lignite thermal degradation. The first model is detailed (named as detailed competitive mechanism), it describes interactions between components and reactions considering the organic structure of lignite and the thermal behaviour of its different chemical bonds. This latter, which is the most detailed chemical mechanism proposed in this study, is then simplified using more or less strong assumptions resulting in three additional simplified models: a simple competitive one, a detailed parallel one and a simple parallel one. The evaluation of those simplified models is carried out to assess if the physical nature of the initial detailed competitive mechanism remains after each simplification. The evaluation of each mechanism is made through the modelling of the total mass loss (ML) and mass loss rate (MLR) as well as the local chemistry parameters through species reaction rates and species densities evolutions as functions of temperature. A focus is made on the maximum reaction rates peaks values and their corresponding temperatures, which have been compared to Differential Scanning Calorimetry (DSC) measurements. The comparison between the 4 models shows that in the contrary of the detailed competitive and the detailed parallel schemes, the simple competitive and simple parallel mechanisms do not capture the MLR peak between 800 K and 1173 K accurately like the first ones do. Moreover, the comparison reveals that the details of the lignite organic structure description into the chemical mechanism is crucial to capture the second part of lignite pyrolysis due to aromatic compounds thermal decomposition.
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Dates et versions

hal-04234528 , version 1 (10-10-2023)

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Citer

Safae Kellali, Franck Richard, Benjamin Batiot, Pierre Cremona, Thomas Rogaume. Modelling of lignite pyrolysis using a finite rate chemistry approach: comparison between parallel and competitive chemical schemes. Journal of Analytical and Applied Pyrolysis, 2023, 172, pp.105975. ⟨10.1016/j.jaap.2023.105975⟩. ⟨hal-04234528⟩
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