Individual torrefaction parameter enhances characteristics of torrefied empty fruit bunches

• Published in: Biomass conversion and biorefinery 2021-04, Vol.11 (2), p.461-472
• Main Authors: Sukiran, Mohamad Azri, Wan Daud, Wan Mohd Ashri, Abnisa, Faisal, Nasrin, Abu Bakar, Astimar, Abdul Aziz, Loh, Soh Kheang
• Format: Article
• Language: English
• Subjects: Biotechnology; Calorific value; Carbon content; Drying; Energy; Fixed beds; Fuel production; Moisture content; Original Article; Particle size; Pretreatment; Pyrolysis; Renewable and Green Energy; Residence time distribution; Solid fuels; Temperature; Thermodynamic properties
• ISSN: 2190-6815; 2190-6823
• DOI: 10.1007/s13399-020-00804-z

Empty fruit bunches (EFB) have great potential to be used as a renewable fuel. Its current low rate of utilization due to high moisture content and low calorific value (CV) can be overcome via a thermal pretreatment, i.e., torrefaction. This study investigated the effects of torrefaction temperature (225, 250, 275, and 300 °C), residence time (20, 40, and 60 min) and particle size (< 106, 106–250, and 500–700 μm) on EFB’s final product distribution and their characteristics in a fixed bed. Structural and thermal properties of the torrefied EFB at different temperatures were determined. Optimum temperature to produce torrefied EFB was identified at 225 °C, while optimum residence time and particle size were 20 min and 500–700 μm, respectively, for a maximum mass (90.3 wt.%) and energy (98.8%) yields. The mass and energy yields of torrefied EFB decreased with increasing temperature and residence time, but increased with increasing particle size of EFB. It was found that the torrefaction temperature had the greatest influence on mass and energy yields of torrefied EFB compared with residence time and particle size. In addition, the study revealed that moisture content had reduced, and carbon content increased with an increasing torrefaction temperature, but those of the O/C ratio, and H and O contents decreased, resulting in an improved CV up to 24.6 MJ kg −1 from its raw form of 17.6 MJ kg −1 . The findings obtained are useful for future upscaling of EFB-based solid fuel production.