Thermogravimetric Assessment and Kinetic Analysis of Forestry Residues Combustion

The development of combustion experiments in a controlled environment is essential for comparing different fuels and quantifying the influence of different key parameters. It is fundamental to understand the transport phenomena at the particle level to obtain reliable results and information for further proper biomass combustion modeling of large-scale equipment. Hence, this paper presents a comprehensive analysis of the thermal decomposition and kinetic of eight samples of forest biomass fuels in terms of combustion behavior by using the thermogravimetric analysis (TGA) technique. The tests were carried out in an oxidizing atmosphere at a heating rate between 5 and 100 °C/min up to 900 °C. It was observed that, for all samples, fuel conversion follows a sequence of drying, devolatilization, and char combustion. Furthermore, differences in chemical and physical composition, as well as in structures and their thermal stability, justify the differences observed between the mass-loss curves of the different fuels. For this, the complexity of kinetic study is addressed in this paper by using different approaches: isoconversional and model-fitting methods. However, the use of isoconversional methods proved ineffective for determining reliable kinetic parameters, due to their sensitivity to particle conversion. A significant variation in activation energy was observed during the devolatilization stage, ranging from 47.92 to 101.30 kJ/mol. For the char oxidation stage, it ranged from 14.97 to 35.48 kJ/mol. These results highlight Eucalyptus as the most reactive species among those studied.