(619aj) Flash Pyrolysis and Fractional Pyrolysis of Oleaginous Biomass in a Fluidized-Bed Reactor

In this study, flash pyrolysis of oleaginous biomass was investigated to produce liquid fuels. Milled soy flakes were used and can be considered a surrogate for algal biomass due to similar compositional, proximate, and ultimate characteristics. A fluidized-bed flash pyrolysis was designed and constructed to facilitate rapid heat transfer to the biomass along with short vapor residence times to minimize secondary degradation of bio-oils and achieve high yields of bio-oil. In addition, a dry-ice packed bed condenser was used to recover the generated vapors. The novel condenser provides a large area of cold surfaces that allow dilute vapors to impinge, condense and coalesce effectively. Single-step pyrolysis experiments were performed at several temperatures over the range 250-610°C with a vapor residence time between 0.3-0.6s. Biooil yields were highest at 550°C (~70% g/g-feed) with only a 12% loss as uncondensed vapors. Moreover, 90% of the feedstock lipids were recovered in the bio-oil fraction. In addition, three-step fractional flash pyrolysis experiments were performed to assess the possibility of producing higher quality bio-oils since a large fraction of protein and carbohydrates degrade at lower temperatures (310-350°C). A low temperature pyrolysis step (250ºC) was first performed and was followed by pyrolysis of the residues at higher temperatures (310 and 530ºC). The bio-oil from last step (530ºC) resulted in higher quality bio-oil with low water- and nitrogen- content, and high heating value of 33 MJ/kg.