Effects of wet torrefaction on reactivity and kinetics of wood under air combustion conditions

FUEL

卷:137

Article

Quang-Vu Bach¹  Khanh-Quang Tran¹  Skreiberg, Oyvind²  Khalil, Roger A.²  Phan, Anh N.³ 

[1] Norwegian Univ Sci & Technol NTNU, Dept Energy & Proc Engn, NO-7491 Trondheim, Norway

[2] SINTEF Energy Res, Dept Thermal Energy, NO-7465 Trondheim, Norway

[3] Newcastle Univ, Sch Chem Engn & Adv Mat, Newcastle Upon Tyne NE1 7RU, Tyne & Wear, England

关键词: Wet torrefaction;    Wood reactivity;    Combustion kinetics;    Kinetic modelling;    Biofuel pretreatment;   

DOI  :  10.1016/j.fuel.2014.08.011

来源: Elsevier

【 摘 要 】

This work continues our assessment of wet torrefaction for energy applications, looking at effects of the process parameters (temperature, holding time and pressure) on the reactivity and intrinsic kinetics of wood under air combustion conditions. Woody materials, Norway spruce and birch, were wet torrefied in various conditions (temperature: 175, 200, 225 degrees C; holding time: 10, 30, 60 min; and pressure: 15.54, 70, 160 bar). The reactivity of the treated and untreated woods was thermogravimetrically examined under a synthetic air environment (21% O-2 and 79% N-2 in volume). A four-pseudo-component model with different reaction orders was adopted for kinetic modelling and extracting the kinetic parameters. The results showed that when increasing either torrefaction temperature or holding time, the torrefied woods behaved more char-like than the raw fuels. However, pressure did not show significant effect on the reactivity. Relatively longer char combustion stages and higher conversion rates (up to 0.5 x 10 (3) s (1)) were observed for the woods after torrefaction. The activation energy was decreased for hemicellulose and char, but increased for cellulose after torrefaction, whereas the trend for lignin is not clear. In addition, the hemicellulose mass fraction decreased after torrefaction (from 0.15 to 0.05 for spruce and from 0.23 to 0.06 for birch). The amount of char in the torrefied woods increased gradually with increasing torrefaction temperature or holding time (from 0.24 to 0.40 for spruce, and from 0.18 to 0.34 for birch). (C) 2014 Elsevier Ltd. All rights reserved.

【 授权许可】

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