(609a) Engine Performance of Biohydrocarbons Produced by Thermal Deoxygenation of Biomass Derived Organic Acids

The University of Maine is pioneering a new biomass conversion technology to produce highly deoxygenated crude bio-oils.  The thermal deoxygenation (TDO) process converts organic acids produced by hydrolysis and dehydration of the carbohydrates in biomass.   The acids are neutralized to form salts and fed to a single atmospheric reactor operating at 450°C.  At these temperatures, the salts decompose by ketonic decarboxylation followed by additional aldol condensation reactions to form carbonates, char and oil with significant yields.  The resulting bio-oil offers a boiling point distribution by SIMDIST from 75-585°C, an oxygen content of less than 0.9 wt. % and a Total Acid Number (TAN) of 1.02 mg KOH/g. 

This presentation addresses the fuel performance of TDO bio-oils through engine performance characterization, in particular diesel combustion characteristics.  Approximately 2L of TDO crude oil was prepared from a series of semi-batch operations using a 1.8L Parr reactor.  The oil samples were combined, washed with water, and blended to 50 vol% with ultra-low sulfur diesel (ULSD).  The resulting fuel was analyzed at Oak Ridge National Laboratory’s Fuels, Engines and Emissions Research Center using a 517cc single cylinder Hatz Diesel engine instrumented to monitor combustion and emissions characteristics.  Tests were run comparatively with base ULSD and conducted at a single speed of 1800 RPM at nine loading conditions.  Results indicate that crude TDO oil is operational over the entire load map with sufficient intake air heating.  A slight power loss is reported due to a lower TDO oil heating value (41 MJ/kg) than ULSD (45 MJ/kg).  Ignition delay of 3 CAD compared to ULSD was reported with a subsequent increase in rate of heat release by 10 CAD as expected given the higher boiling point distribution.  No adverse material or engine management problems were reported.  Results indicate that TDO crude oils have the potential to displace conventional distillate fuels with minimal upgrading.