Kinetic Scheme to Predict Product Composition of Biomass Torrefaction

A kinetic scheme for the prediction of product composition of torrefaction is presented in this work. The scheme is based on a pyrolysis scheme for fast pyrolysis of small ash free biomass particles and was adapted to consider the presence of secondary char formation reactions, the inhibition of sugar formation due to the catalytic effect of alkali metals in biomass, as well as the typical hemicellulose structure of hardwoods. The torrgas composition predicted by the model is compared to experimental data of torrefaction in a lab-scale packed bed reactor. It is shown that the adapted model is able to predict the yields of the main volatile groups, i.e., permanent gases, light and heavy condensable species and the yields of the several groups in which condensable species were classified based on their structure, i.e., carbonyls and alcohols, furans, phenolics as well as water vapour.