In-situ torrefaction and spherical pelletization of partially pre-torrefied hybrid poplar

A novel compacted, spherical, torrefied biomass pellet is discussed. Pellets were pressed in a heated mould and die, and torrefied in-situ (at 280 °C) from both untorrefied and pre-torrefied (at 250 °C) hybrid poplar sawdust prior to pelleting. Spherical pellets were successfully produced from both input materials. The calorific value of these pellets, referred to as “QʹPellets”, is 20.78 MJ kg−1–21.60 MJ kg−1 on a moisture and ash free basis, which compares favourably with lignite coal. The ash content of QʹPellets was as high as a mass fraction of 2.07%–5.08%. QʹPellets are demonstrated to be uniquely durable, as they did not abrade in a tumbling can test or fracture in an impact resistance (drop) test.