Kinetics of Charcoal Devolatilization

• Published in: Energy & fuels 2002-05, Vol.16 (3), p.724-731
• Main Authors: Várhegyi, Gábor, Szabó, Piroska, Antal, Michael Jerry
• Format: Article
• Language: English
• Subjects: Applied sciences; Combustion of solid fuels; Combustion. Flame; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Theoretical studies. Data and constants. Metering
• ISSN: 0887-0624; 1520-5029
• DOI: 10.1021/ef010227v

The devolatilization kinetics of a biomass charcoal was studied by thermogravimetry−mass spectrometry. The overall mass loss rate (DTG curve) and the mass spectrometric intensities of ions H2 +, CH3 +, C2H2 +, C2H3 +, and C2H5 + were evaluated. The distributed activation energy model (DAEM) was employed, since it can mathematically represent the physical and chemical inhomogeneity of the charcoal. Some of the evaluated experimental curves consisted of 2−4 overlapping partial peaks. In those cases parallel reactions were assumed, and each reaction was described by a DAEM. The unknown parameters were determined by a simultaneous least-squares evaluation of a series of experiments. Parameters were identified that enabled the model to describe equally well the nonisothermal experiments and the experiments containing isothermal sections. Kinetic information was obtained on the drying and the evaporation of the organics trapped on the surface of the samples, the decomposition of the side groups with low thermal stability, the splitting-off of the more resistant side groups and the formation of the aromatic rings, and the elimination of heteroaromatic oxygen followed by the formation of polyaromatic structures during carbonization.