Fast Pyrolysis of Biomass in Pyrolysis Gas: Fractionation of Pyrolysis Vapors Using a Spray of Bio-oil

Japanese cedar sawdust was pyrolyzed in a bubbling fluidized-bed reactor to study the effects of condensers with and without spraying and the different fluidizing gases on product yields. The temperature in the condenser affected the bio-oil yield and composition. Test results showed that the condenser with spraying had a lower temperature, preventing vapor and liquid phases in the condenser from being further reacted and increasing the bio-oil yield. The pyrolysis vapors were condensed to bio-oil according to the various boiling points and condensation methods of the vapors. The condenser with spraying separated bio-oil into an oily portion rich in phenolic compounds with high boiling points and an aqueous portion rich in moisture with low boiling points. Sawdust pyrolyzed in pyrolysis gas or nitrogen gas also affected the product yields. Sawdust pyrolyzed in pyrolysis gas increased the bio-oil yield and the concentrations of H-2, CO, and CH4 combustible gases in the gas phase. When the sawdust was pyrolyzed at 460 degrees C in pyrolysis gas and the condenser with spraying, a maximum bio-oil yield of 71.1 wt % was obtained.