Pyrolysis of Huadian Oil Shale in an Infrared Heating Reactor

Pyrolysis of Huadian oil shale was investigated in a newly designed shallow fixed bed reactor mounted with infrared heating to clarify the pyrolysis behavior at different heating rates and pyrolysis temperatures under minimized secondary reactions to volatiles in an oil shale bed. The maximum shale oil recovery was obtained under the proper conditions of a heating rate of 0.5 degrees C/s, a pyrolysis temperature of about 550 degrees C, a reduced reaction pressure (0.6 atm in this work), and for a single layer oil shale bed. The highest shale oil yield under such conditions was close to 100% of the Fischer Assay oil yield (11.10 wt % of dry basis). For the adopted infrared-heating reactor, increasing the heating, rate decreased the shale oil yield but increased the gas production. The total hydrogen in volatile products including shale oil and pyrolysis gas increased with raising the heating rate, and the total volatile production was higher for the infrared quick heating pyrolysis (heating rate: 25 degrees C/s) than that for the Fischer Assay. The shale oil from the infrared quick heating pyrolysis had also more light fraction. Experiment also found that pyrolyzing the multilayer oil shale bed lowered the shale oil yield in comparison with the pyrolysis of a single-layer material bed. Thus, adopting a single-layer oil shale bed, low infrared heating rates, and reduced reaction pressures obviously suppressed the secondary reactions toward volatiles to have consequently high shale oil yield. High infrared heating rate facilitated volatile and hydrogen production but led to more serious secondary reactions to lower the shale oil yield.