Prediction of higher heating values (HHVs) and energy yield during torrefaction via kinetics

Torrefaction is a promising process to upgrade biomass and produce solid biofuel. The purpose of this study is to predict the higher heating values (HHVs) of biomass and energy yield during torrefaction. A two-step model and a direct method are adopted to obtain the torrefaction kinetics and the prediction of elemental composition in the present study. The experiments were performed at the temperature range of 200-230 degrees C in a pilot-scale reactor, which can record the mass loss dynamics during the treatment. The results point out that the prediction of solid yield and elemental composition profiles are in good agreement with the experiments. The predicted HHVs are calculated from C, H, and O based on an empirical equation. As a while, the HHVs of torrefied wood are in the range of 19.85-20.71 MJ kg(-1) and the energy yields are in the range of 92.3-97.4 %. (C) 2019 The Authors. Published by Elsevier Ltd.