Characterization of Torrefied Willow for Combustion Application

This study examines combustible properties of torrefied willow produced in a newly developed moving bed reactor. Effect of temperature (210-300 degrees C), residence time (30-60 min) and oxygen concentration (0.0-2.4%) on torrefied willow production were studied. The weight and energy yield of the products were varied from 42% to 97%, and 61% to 98%, respectively; depending upon the operating parameters. After the thermal treatment, torrefied biomass had about 31% more higher heating value than the raw sample. No significant difference in heating value was observed with an inert environment and oxygen with 2.4% concentration. The optimum temperature for hydrophobicity of willow was found at 275 degrees C where minimum absorption of moisture uptake was seen. Any further increase in operating temperature increased the moisture uptake. During pelletization, torrefied biomass required more pressure to build pellets than the raw willow biomass. Torrefaction had a negative impact on pellet formation and pellet strength. Pellets produced from torrefied biomass without additives were very weak in bonding.