Gasification of pelletized biomass in a pilot scale downdraft gasifier

This work presents a pilot-scale investigation aimed at assessing the feasibility and reliability of biomass pellet gasification. Wood sawdust and sunflower seeds pellets were tested in a 200 kW downdraft gasifier operating with air as gasifying agent. The gasification of pelletized biomass led to rather high and unstable pressure drops, reducing the gasifier productivity and stability. Furthermore the generation of fine residues compromised the operation of wet ash removal systems. On the other hand, good syngas compositions (H2 17.2%, N2 46.0%, CH4 2.5%, CO 21.2%, CO2 12.6%, and C2H4 0.4%), specific gas production (2.2–2.4 N m3 kg−1) and cold gas efficiency (67.7–70.0%) were achieved. For these reasons pelletized biomass should be considered only as complementary fuel in co-gasification with other feedstock.