(604p) The Effect of Heat Carrier Properties on Pyrolysis Products in an Auger Pyrolyzer

Authors: 
Daugaard, T. J., Iowa State University
Wright, M. M., Iowa State University
Brown, R. C., Iowa State University
Dalluge, D., Iowa State University

The objective of this research was to determine how different heat carrier properties affect the yield and characteristics of pyrolysis products in an auger reactor.  Auger pyrolyzers have gained interest as alternative reactors due to their minimal inert gas requirement while still achieving similar yields to fluidized bed reactors. Additionally, auger pyrolyzers with direct heating via heat carrier provide higher heat transfer rates over conventional indirect heating auger pyrolyzers. For this study we pyrolyzed up to 1 kg/hr of red oak in a twin-screw, lab-scale auger reactor at 515⁰C. Multiple heat carriers with varying specific heat capacities (500-830 J/kg-K) and thermal conductivities (0.2-120 W/m-K) were tested.  The heat carriers tested included stainless steel, silicon carbide, fine sand (250-600μm) and coarse sand (600-1000μm).  A cold gas quench system was used to collect the bio-oil into two fractions: a heavy phase and an aqueous phase.  Proximate and ultimate analyses were conducted on both bio-oil fractions and char.  Moisture and solids content was also determined for both bio-oil fractions. Identification of select bio-oil compounds was conducted. Bio-oil yields ranged from 64-68 wt. % across all heat carriers.  Char and non-condensable gas yields ranged from 15-25 wt. % and 10-15 wt. %, respectively.  More fundamental studies are needed to optimize the yields and quality of pyrolysis products in an auger pyrolyzer.  

*Funding for this project was provided by the Phillips 66 Company.