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Combustion Characteristics of Biomass Charcoals Produced at Different Carbonization Conditions: A Kinetic Study

Wang, Liang, Várhegyi, Gábor, Skreiberg, Øyvind, Li, Tian, Grønli, Morten, Antal, Michael J.
Energy & Fuels 2016 v.30 no.4 pp. 3186-3197
Picea, activation energy, atmospheric pressure, biomass, carbonization, charcoal, combustion, kinetics, least squares, oxygen, plant residues, temperature, thermogravimetry
The combustion properties of spruce chars and spruce forest residue chars were studied in the kinetic regime by a series of thermogravimetric analysis (TGA) experiments. The work aimed at establishing how the pressure of the char preparation affects the reactivity with oxygen. Parts of the chars were prepared from a thin layer of biomass in inert gas flow at atmospheric pressure and 0.8 MPa. Other chars were formed in a pressurized reactor by a flash carbonization method [Antal, M. J., Jr.; Mochidzuki, K.; Paredes, L. S. Flash carbonization of biomass. Ind. Eng. Chem. Res. 2003, 42 (16), 3690−3699, DOI: 10.1021/ie0301839]. Despite the differences in the preparation, remarkable similarities were observed in the combustion behavior of the samples. The kinetics of the char burnoff was described by assuming three partial reactions. A total of 18 experiments at three different temperature programs were evaluated by the method of least squares to obtain dependable kinetic model variants. A common activation energy of 150 kJ/mol gave a reasonable description for the three partial reactions in all experiments.