Torrefaction of oil palm frond petiole: effect of particle sizes, sections and batches

This study aimed to investigate the effect of batches (1, 2 and 3), particle sizes (<250 µm, range of 300 µm to 500 µm), and sections (bottom, middle and top) on combustion performance of the oil palm frond (OPF) petiole after torrefaction at 275 °C. The higher heating value (HHV), mass yield, energy yield, HHV yield and proximate analyses of the untorrefied and torrefied OPF petiole for all cases were determined. The comparison between the untorrefied and torrefied OPF petiole as well as an international benchmark was also performed. In this study, the highest HHV of the torrefied OPF petiole (22.85±0.07MJ/kg) was obtained at the bottom section with the particle size of < 250 µm. Furthermore, the fixed carbon content of the torrefied OPF petiole increased, whereas the volatile matter, moisture content, mass and energy yields decreased for all cases after torrefaction. HHV yield of OPF petiole was recorded up to 141% after torrefaction. The ash content was sufficiently satisfied the international benchmark for most cases, except for top section (300-500µm). The changes in combustion properties of the torrefied OPF petiole for all cases were found to be insignificant whereas significant improvement could be observed when compared to untorrefied OPF petiole. Overall, the study revealed that the appropriate particle size for torrefaction can promote it to be a vital source for energy production from oil palm biomass