469496 Effects of Recycling Regenerated Heat Carrier on the Performance of an Auger Pyrolysis Reactor
A twin-screw, lab-scale auger reactor was used to pyrolyze up to 1 kg/hr of red oak at 515°C. The heat carriers of interest in this study included fine (250-600 µm) and coarse sand (600-1000 µm). Pyrolysis trials using recycled heat carrier were conducted at up to 5 recycles. The heat carrier was regenerated following each trial to remove any carbon residue. A cold gas quench system was used to collect the bio-oil into two fractions: a heavy phase and an aqueous phase. Product characterization included ultimate and proximate analysis of the bio-oil and char. Gas chromatography of the bio-oil fractions was also conducted. Product yields of bio-oil (~60 wt. %), char (~17 wt. %) and gas (~18wt %) were consistent across the limited number of recycle trials. Heat carrier attrition varied from 4 to 8 wt. %, and the mean particle size decreased following the recycled trials. These results indicate that heat carrier properties may change significantly over a short number of rotations, but their impacts on biomass pyrolysis yields is small. Long-term tests would be necessary to determine heat carrier replacement rates in order to avoid significant impacts on bio-oil yields and quality.
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