Influence of Torrefaction on Single Particle Combustion of Wood

This study focuses on the influence of torrefaction on the char reactivity, char yield, and combustion time of 3-5 mm spherical wood particles in a single particle combustion reactor (SPC) operating at a nominal temperature of 1231 °C. The devolatilization times were reduced and the char burnout times were increased with increasing torrefaction degree. The devolatilization time depended linearly on the particle mass. The torrefaction pretreatment resulted in a marked increase in char yield and char particle density but no intrinsic reactivity change as determined by thermogravimetric analysis. The char yield and char particle density increased from 9 wt % and 123 kg/m³ for raw particles to 14 wt % and 259 kg/m3 for particles pretreated at 290 °C for 4 h. The results of this study demonstrate that the higher char yield and density are the main reasons for the longer combustion time of torrefied wood.