Torrefied biomass pellet production from rubber wood wastes and corn wastes in pilot-scale vibrating torrefaction system

Combining densification with torrefaction can substantially improve fuel properties, including energy content, grindability, and hydrophobicity, enabling torrefied pellets to replace coal in pulverized fuel boilers. This study investigates biomass pellet torrefaction using an innovative vibrating torrefaction system developed in this work, representing the first pilot-scale technical assessment of Thai biomass feedstocks. The objectives were to evaluate torrefied pellet properties and assess production costs. Rubber wood waste pellets (RWP) and corn waste pellets (CWP) were torrefied at 220–300 °C with residence times of 16 and 30 mins. The results indicate that increasing torrefaction severity enhanced fuel quality, with the heating value (HHV) reaching 22.4 MJ/kg, approximately 20% higher than raw pellets, along with improved grindability and moisture resistance. These improvements were accompanied by reductions in mass and energy yields, indicating that heating value alone is insufficient to assess process performance and that energy yield must also be considered. Specific electricity consumption ranged from 624 to 1161 kWh/ton of product, depending on torrefaction severity and mass yield. A preliminary cost analysis, accounting for capital investment, feedstock cost and electricity consumption, estimated production costs of 8000–11,000 THB/ton of torrefied pellets.