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Changes in charcoals and by-products charactesistics through pressurized pyrolysis

Numazawa S., Girard P., Mouras S., Rousset P.. 1998. In : Commission of the European Communities. Biomass for energy and industry. Proceedings of the international conference. s.l. : CARMEN, p. 1806-1814. European Conference and Technology Exhibition. 10, 1998-06-08/1998-06-11, Wuerzburg (Allemagne).

The laboratory scale slow atmospheric pyrolysis for charcoal production shows solid yield which varies from 25 to 30%. When it is produced with conventional technologies i.e. metal kiln, efficiency might be drastically reduced if the process is not properly managed, to drop to 10 to 15% on dry basis. Therefore, energy efficiency can't be over 50% and more than 70% of the raw wood is lost through gas and vapour, creating environmental problems. The scope of this paper is to present the results obtained under pressurized slow pyrolysis below 10 bars and to corppare products characteristics as a function of pressure. Tropical amazonian wood species have been tested at 450T at different pressure levels. The results show on increase in solid from atmospheric pressure to 4.2 bars: respectively 34 to 43%. The charcoal produced under pressure present a different chemical composition, especially in volatile content. The Tatajuba charcoal pyrolysed under pressure (4.2 bars) present about 32% more volatile content than charcoal produced at atmospheric pressure. Our first analysis show that the gas and liquid components obtained during wood pyrolysis are the same as with wood pyrolysed at atmospheric pressure, but with different amounts.

Mots-clés : pyrolyse; charbon de bois; sous-produit du charbon

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