Pyrolysis and thermogravimetry of blended and nonblended residues of pine and eucalyptus forestry woods

In this article, we present the results of the thermogravimetric analysis (TGA) of blended and nonblended residues of Pinus taeda and Eucalyptus benthamii submitted to thermal degradation at heating rates of 5, 15, and 30 K/min, up to a maximum of 900 K. The temperature range is divided into three intervals (corresponding to the pyrolysis stages of drying, devolatilization, and char formation) and each thermal evolution curve is fitted by a modified version of the Coats-Redfern method. The kinetic parameters of the Arrhenius equation are then calculated. The adoption of three temperature intervals provides a better approximation and yields more realistic values, when compared to the single-temperature interval approach found in most of the consulted literature. Kinetic analysis shows that each evolution profile can be represented as a single first-order reaction. Moisture, volatile matter, ash, and fixed carbon contents are measured. Among the wood residues investigated, sawdust mixtures and barks of pine seem to be the most suitable fuels for heat generation. On one hand, the practical aim of this study is to advance the use of biomass residues as a renewable energy source among local industries. On the other hand, in theoretical terms, results might help devise new mathematical models and more efficient reaction mechanisms for the heterogeneous combustion of solid particles, which is a complex phenomenon still to be fully understood. (c) 2016 American Institute of Chemical Engineers Environ Prog, 35: 1521-1528, 2016