Fundamental Study on the Production of 'Hyper Wood Pellet'-Effect of Torrefaction Condition on Grinding and Pelletizing Properties

摘要

In order to upgrade the conventional wood pellet, Japanese softwood and hardwood chips were torrefied at around 200-350 ℃, and pelletized. The characteristics of the torrefied material/pellets such as their calorific value, grinding energy, pelletizing energy and elemental composition, were also evaluated in this study. The calorific value rose with increasing torrefaction temperature and exceeded 25 MJ/kg (an increase of nearly 40% compared to the untreated state) for torrefaction at around 350 ℃. The grinding energy greatly decreased with increasing torrefaction temperature, and the reduction was larger for Japanese oak hardwood chips. The pelletization energy for the torrefied material tended to be slightly smaller than in the untreated case. People named such torrefied pellet as "hyper wood pellet".