Structural and compositional changes in eucalyptus wood chips subjected to dry torrefaction

Abstract

The aim of this study was to evaluate the structural and compositional changes in eucalyptus wood chips subjected to dry torrefaction. The experiment was conducted in a semi-continuous screw reactor with indirect heating system. Wood chips samples of three initial moisture contents (0, 15 and 30% dry basis) were torrefied up to three final temperatures (220, 260 and 300 °C) and at three heating times (10, 15 and 20 min). The effect of these variables was evaluated through the analysis of chemical composition, thermogravimetry and mechanical durability of the torrefied wood chips. The increase at temperature and time of torrefaction, as well as the drop in the initial moisture content, promoted significant structural and compositional changes in the wood chips. The torrefied samples present a higher resistance to thermal degradation, more friable structure, higher lignin and lower polysaccharides contents than the untreated samples. These changes made it possible to increase the quality of the eucalyptus wood chips to be use as a solid fuel.