Torrefaction of tomato industry residues

The standardization is an important aspect for fuel products. Some residual biomass are highly heterogeneous making their energy use rather difficult. Torrefaction can represent an interesting process to improve the standardization and quality of the lignocellulosic biomass. In the present research torrefaction has been applied on tomato peels, an important Italian industry residue. Different residence times and torrefaction temperatures have been employed in a bench top torrefaction reactor. Proximate, ultimate, thermogravimetric and infrared analyses of raw and torrefied material have been performed to evaluate the influence of the process. From the mildest condition studied to the most severe one, mass yield, energy yield and energy densification vary in the ranges of 94.7-69.9%, 98.0-86.0% and 1.04-1.23 respectively. According to mass and energy yields, ultimate analysis and thermogravimetric profiles, temperature parameter results more significant than residence time. Torrefaction makes the material increasingly hydrophobic as torrefaction temperature increases. This results in a more biologically stable and standardized material suitable to be employed as fuel for energy application. The results of this paper provide useful indications and suggest a mild torrefaction.