Oxidative pyrolysis of wood chips and of wood pellets in a downdraft continuous fixed bed reactor

Elias Daouk (1, 2, 3) , Laurent van De Steene (3) , Frederic Paviet (1) , Éric Martin (3) , Jeremy Valette (3) , Sylvain Salvador (2)

1 GEPEA - Laboratoire de génie des procédés - environnement - agroalimentaire
2 RAPSODEE - Centre de recherche d'Albi en génie des procédés des solides divisés, de l'énergie et de l'environnement
3 Cirad - Centre de Coopération Internationale en Recherche Agronomique pour le Développement

In air staged gasification and advanced carbonization processes, oxidative pyrolysis occurs in downdraft continuous fixed bed reactors. An oxidation zone separates the virgin fuel from the resulting char and propagates upward. Here, the oxidation zone was stabilized at a fixed elevation in a 20 cm I.D. fixed bed reactor using wood chips or wood pellets. In controlled continuous operating mode, we investigated the impact of air flux and bed bulk density on the behavior of the oxidation zone in terms of wood consumption, and yields of chit., gas and tars. An air:wood mass ratio of 0.7 was measured and in our operating conditions, and was not sensitive to air mass flux and bed density. With oxidative pyrolysis, yields of organic condensates were lower than with allothermal pyrolysis, whereas the production of pyrolysis water and permanent gases increased. Finally, the oxidation zone was shown to be flat and horizontal in a wood pellet bed but inclined in a wood chip bed.

Mots clés: Smoldering; Biomass; Yields of products; Fixed-bed; Oxidative pyrolysis; Fixed-bed; Biomass; Smoldering; Yields of products

Domaines: Génie des procédés; Génie chimique

Elias Daouk, Laurent van De Steene, Frederic Paviet, Éric Martin, Jeremy Valette, et al.. Oxidative pyrolysis of wood chips and of wood pellets in a downdraft continuous fixed bed reactor. Fuel, 2017, 196, pp.408-418. ⟨10.1016/j.fuel.2017.02.012⟩. ⟨hal-01619256⟩