TORREFIED MATERIAL: AN ATTRACTIVE FEED FOR FLASH PYROLYSIS?

摘要

Bio-oils produced via flash pyrolysis offer interesting possibilities as renewable fuels; they are however of a lower quality than the fossil fuels they are aiming to replace, making bio-oils currently unsuitable for conventional fuel applications. A torrefaction pre-treatment could partly solve the quality issue by removing some highly oxygenated compounds from the biomass feedstock, leading to bio-oils with lower oxygen contents and increased heating values. Experiments were carried out using an entrained down flow reactor to verify these claims, using two biomass streams: ash wood and mixed waste wood. For mixed waste wood, an untreated and a torrefied stream was used; for ash wood, an untreated and two torrefied streams were used, with torrefaction temperatures of 250°C and 265°C. Furthermore, the torrefied streams were available in chips and in pellets. Preliminary results show indeed a trend of decreased O/C ratios in the Van Krevelen diagram, indicating bio-oil quality closer to fossil fuels. Pelletizing seems to have the same effect as a slightly increased torrefaction severity.