Upgrading of oil palm biomass by torrefaction process: A preliminary study

Abstract

The palm oil industry produces an abundance of oil palm biomass, which is mostly produced by plantation and milling activities. However, these biomass materials have low calorific value, high moisture and oxygen contents, and are hygroscopic in nature making them unsuitable as a fuel. Torrefaction is found to be a promising technique for the biomass dewatering and upgrading its quality before utilization. This study investigated the effects of torrefaction temperature (200-300 °C) on the mass and energy yield of empty fruit bunches (EFB), oil palm frond (OPF) and oil palm trunk (OPT) in a fixed bed reactor. The torrefied products were then characterized for their fuel properties such as calorific value (CV), elemental contents and ash content, while the energy yields was calculated based on the obtained mass of torrefied yield and CV. Among the oil palm biomass, OPF gave an optimum torrefied and energy yield about 94 wt.% and 99 %, respectively, which obtained at 200 °C for 30 min. This study also showed that the CV of torrefied products increases as temperature increases from 200 °C to 300 °C. The highest CV of 21 MJ/kg was obtained at the torrefaction temperature of 300 °C using EFB as a feedstock. The physicochemical properties of torrefied oil palm biomass were provided some indications on the suitability of these materials for further bioenergy processes such as combustion and palletization.