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Differences in Bed Agglomeration Behavior during the Fast Pyrolysis of Mallee Bark, Leaf, and Wood in a Fluidized-Bed Reactor at 500 °C

Burton, Alan, Wu, Hongwei
Energy & Fuels 2015 v.29 no.6 pp. 3753-3759
Eucalyptus, bark, biofuels, biomass, ethanol, evaporation, feedstocks, fluidized beds, leaves, pyrolysis, solvents, trees, washing, wood
This paper reports the significant differences in bed agglomeration behavior during the fast pyrolysis of various mallee biomass components (leaf, wood, and bark) in a fluidized-bed reactor at 500 °C. The pyrolysis of mallee leaf and bark led to significant bed agglomeration yields of 12.0 and 13.4%, respectively, while the pyrolysis of the wood component results in little bed agglomeration yield of <0.1%. Ethanol washing of the leaf and bark samples was carried out to prepare solvent-extracted leaf and bark samples (the solid residues after extraction) and the extract samples (obtained after evaporating the solvent from the extracted solvent solutions). Subsequent pyrolysis of the solvent-extracted leaf and bark samples showed drastically reduced bed agglomeration yields of 6.0 and 1.3%, respectively. Direct pyrolysis of the extract samples from leaf and bark resulted in substantial bed agglomeration yields of 24.4 and 34.1%, respectively, suggesting that the extractives within biomass play a critical role in the bed agglomeration during biomass fast pyrolysis. The experimental results indicate that, if the biomass from the whole mallee tree is used as a feedstock for bio-oil production via fluidized-bed fast pyrolysis, then the leaf and bark components are expected to cause bed agglomeration, because of the substantial amount of extractives present in these biomass materials.