Pilot scale ring and die pelletizing of reed canary grass (Phalaris arundinacea L.) was performed in experimental
designs for screening and optimization of pellet quality parameters bulk density and durability
and for determination of specific energy consumption under different settings. Control variables included
die temperature, raw material moisture content, and steam conditioning. By using a unique experimental
setup, where die temperature could be controlled, all factors could be varied independently.
Results from the screening design, showed that a low die temperature was necessary to avoid discontinuous
production conditions and guided the choice of settings in the optimization design for obtaining
high pellet quality. Settings for reaching the suggested quality criteria of pellets for non-industrial use
with a durability P97.5% and a bulk density of P600 kg/m3 were easiest to meet at die temperatures
around 30 C and a material temperature of approximately 30–40 C (equal to 2–4 kg steam/h) for the full
range of raw material moisture content (12–16%).