LAUSR

Abstract Thailand is an agriculture-based country. It produces large amounts of open burned agricultural residues. A strategy to use them as biofuel all year round is to enhance their fuel properties by coupling blending and thermochemical pre-treatment. In this study, the pyrolytic behaviour of major residues (napier grass, rice straw, cassava stalks and corn cob) exposed to a high torrefaction temperature (300 °C) was investigated for various blending ratios, i.e. 100:0, 50:50 and 70:30. The release of chlorine was quantified for each biomass blend, including, a new fouling risk index ratio. Also, the synergistic effects of both ignition and burnout temperatures were analysed. Rice starw and napier grass were found to be characterised by a high ash content and so large amounts of solid yield after torrefaction. Raw biomasses and untreated biomass blends were found to be less suitable as biofuel than torrefied biomasses. The ratio K2O:SiO2, indicator of fouling risk during combustion, was found to be low for all torrefied blends. The HHV:Cl ratio, indicator of combustion quality, indicated that NG mixed with RS (50:50 proportion) is the most promising blend. Significant synergetic effects were observed for biomasses mixed before torrefaction. The burnout temperatures for raw and torrefied biomasses were identified in the range 773–787 °C and 786–795 °C.