Improvement of Biomass Fuel Properties for Rice Straw Pellets Using Torrefaction and Mixing with Wood Chips

Abstract

Utilization of rice pellets as biomass fuel has many challenges compared with wood pellets, including low heating value, low bulk density, and high ash content, that cause high logistic costs and clinker formation. To solve these problems, this study focused on upgrading the quality of rice straw pellets to improve logistic efficiency by torrefaction and mixing with wood chips. Torrefaction and mixing with wood chips was effective to improve the energy density, the mechanical durability and the contents of fixed carbon, nitrogen, sulfur and ash, leading to the improvement of both logistic efficiency and combustion behavior. The burning test showed that increases in the fixed carbon content and the mechanical durability contributed to stable increases in the temperature inside the furnace during starting up and reduced the amount of ash in the exhaust gas during stable combustion.