Production and Evaluation Method of Heat-Treated Biomass Pellet Fuels

Abstract

　　　Heat treatment is one of the upgrading technologies for biomass benefication. The torrefaction process, which means low temperature heat treatment of woody biomass around 250 - 320 ℃ without oxygen atmosphere, has recently emerged as a promising technology to upgrade biomass fuel characteristics. Torrefied woody biomass fuel holds higher energy density than conventional charcoal, and better hydrophobicity and requires lower grinding energy than wood chip and pellet. One of the usage of torrefied fuels is co-firing with coal in large scale power generation plant, where the co-firing ratio can be greatly increased in the case of the torrefied fuel. Also, there is possibility to use as fuel for the heating appliance in small scale. Characterization of heat-treated biomass fuel is generally similar to that of coal, while there are some differences in determinations of ash content, ash fusion behavior, sieving and so on. However, most of the characterization methods have been published as international standards. The stakeholders dealing with solid biomass fuels in Japan shall strongly contribute to discuss the international standards.