Valorization of corncob through torrefaction process

Abstract

Corncobs is a waste of post-harvest corn processing that has great potential to be used as a source of renewable solid fuel. Its high moisture and volatile solids content produces a lot of smoke when corncob is burned, so it is rarely used as fuel. This study aims to improve the quality of corncob fuel through the torrefaction process. The corncob was naturally dried using sunrays for two days and cut into pieces of 1-3 cm in size. The torrefaction process was carried out using a cylindrical rotary reactor which operated at a speed of 30 RPM and was heated using an external heat source. The variations of torrefaction time were 30, 40, and 60 minutes. The parameters to be observed included moisture content, ash content, volatile content, calorific value, and hydrophobicity of materials. The results showed that the torrefaction process improved the quality of corncobs as seen from an increase in calorific value, an increase in hydrophobicity. In this study, the calorific value of the torrefied corncobs was 18.89 MJ/kg to 21.61 MJ/kg, which was higher than the caloric value of the non-torrefied corncobs of 17.66 MJ/kg. The torrefied corncobs are also more hydrophobic and absorb less water than the non-torrefied corncobs.