Ranzi detailed kinetic scheme predictions vs. detailed experimental results
Résumé
Ranzi et al. proposed one of the most detailed biomass pyrolysis model [Ranzi et al., 2013]. The Ranzi lumped kinetic scheme is very interesting since it described the thermal decomposition of each biomass polymers (cellulose, hemicellulose and lignins) through 25 parallel and consecutive reactions that respect atomic balances. Thirty-nine molecules are defined: this allows to compute the gas and vapour composition but also the solid residue composition which is made of biomass polymers, char, but also different intermediates. In this work, we will present a comparison between the Ranzi model predictions and different experimental data that have been obtained with the following samples : Douglas fir, oak, miscanthus, extracts from miscanthus : cellulose, holocellulose and lignin organosolv. Slow pyrolysis data have been obtained through different setups: mass loss kinetics through Thermogravimetric analysis and heat release kinetics through Differential Scanning Calorimetry. A fixed bed setup allows to recover all the products that are characterized through elementary and molecular analysis. All these data could be compared with the Ranzi pyrolysis model predictions if the thermal conditions are well-understood. Fast pyrolysis experiments have also been achieved thanks to a micro-fluidized bed and an image furnace [Christodoulou et al., 2012]. In this case, there are internal temperature gradient in the solid particles during pyrolysis : the kinetic scheme of Ranzi model needs to be coupled to an accurate internal heat transfer model in order to compare simulated and experimental results. It will be shown that Ranzi model is a great progress in the field, even if there are still improvements to achieve so that it could represent all the features of biomass pyrolysis such as minerals catalytic effect. RANZI, Eliseo, CORBETTA, Michele, MANENTI, Flavio, et al. Chemical Engineering Science, 2013. CHRISTODOULOU, Mélina, MAUVIEL, Guillain, LÉDÉ, Jacques, et al. Journal of Analytical and Applied Pyrolysis, 2012.