Torrefaction of Portuguese woody biomasses and the evaluation of its properties

Abstract

Torrefaction is an option for improving biomass properties for fuel application. Biomass undergoes chemical changes reflected on the upgrading of its properties as a biofuel, such as higher calorific power, lower O/C and H/C ratios, lower higroscopicity or better grindability. The objectives of this experimental study were to analyze the effects of torrefaction, under standard conditions of 265 ºC, and residence time of 15 minutes in a nitrogen atmosphere and during a total 1h45m heating period, on a set of sixteen woody biomasses coming from poplar short rotation coppice (SRC) and other Portuguese roundwoods. Average mass loss was higher than 40%. The set of poplar clones and common broom provided torrefied products with higher quality than the set of roundwood forest species. The results on other parameters for proximate and ultimate analysis corroborate this global picture. Correlation analysis showed a higher degree of interconnectedness between LHV and proximate analysis results, for poplar clones and common broom, comparatively with roundwood biomasses.