Systems, methods and techniques for torrefaction

A method for operating a system for torrefaction of waste material comprising biogenic and plastic material, the method comprising:

• processing the waste material to generate a coarse size waste material, the coarse size waste material having a size no greater than 310 mm;
• processing the coarse size waste material to generate a fine size waste material, the fine size waste material having a size no greater than 60 mm;
• processing the fine size waste material to generate pre-processed waste material, comprising:
• operating a shredding unit at a speed less than 500 rpm
• the pre-processed waste material having an aspect ratio between 0.8:1 and 1.2:1 and a largest dimension of less than 4 millimeters (mm);
• wherein a density of the pre-processed waste material is between 105 kg/m3 and 120 kg/m3;
• receiving the pre-processed waste material in an airlock;
• providing the pre-processed waste material from the airlock to a heating and compaction unit;
• compressing and heating the pre-processed waste material in the heating and compaction unit, including heating the heating and compaction unit to a temperature between 180° C. and 220° C.;
• providing the compacted waste material to a reactor system such that a residence time in the reactor system is between 2 minutes and 30 minutes;
• heating the compacted waste material in the reactor system to a temperature of 280° C.-500° C.;
• extruding material from the reactor system;
• and
• cutting the extruded material into pellets.