Screw pyrolysis/torrefaction mini-plant


A slow pyrolysis reactor mini-plant (BTG Biomass Technology Group, The Netherlands), based on the principle of a rotating screw (auger) for passing biomass through the reactor, has recently been installed within the laboratory of the department of biosystems engineering.  The process is capable of pyrolysing biomass in nitrogen at temperatures of up to 650 °C at a continuous feeding rate of up to 2 kg/h.  The process is highly automated and six separate temperature control loops along the two-reactor screws allow significant temperature profile manipulation.  Additional temperature measurements can also be taken directly from the screw blade. A final cooling screw allows the safe capturing of solid products prior to further analysis.  Gases and vapours are cooled in a direct spray condenser and a secondary indirect cooler.  Uncondensed gases are filtered, quantified, and may be sampled for further analysis. Condensed vapours are collected after experiments for quantification and analysis.  The screw pyrolyser will be used for the validation of pyrolysis models; producing char from various biomass sources for further testing, and to give further insight on the flow and mixing of biomass in screw reactors.