Investigating the Effects of Heating Rate and Granulation on Extracted Oil-Shale using Microwaves and Conventional Heating Methods

The quality and extraction rate of oil shale is a significant challenge in the oil shale processing field. In this article, the effects of heating rate and grain size as fundamental parameters in oil shale production from the QaliKuh reservoir in Iran on the quantity and quality of produced oil shale are explored as other sources. Fisher’s developed microwaves at ۲۴۵۰ kHz were used to heat several oil shale samples at power levels of ۶۵۰, ۹۰۰, and ۱۲۰۰ watts up to coking temperature (۷۰۰ °C). It was observed that the amount of oil produced increased from ۵.۲% to ۵.۹%, then it reduced to ۵% weight of the sample as the microwave heating rate increased; however, the quality of the oil (asphaltene reduced from ۲۵% to ۱۹%, sulfur content reduced from ۱۶% to ۷%, and carbon percentage increased from ۶۷% to ۷۸%,) improved. In contrast, conventional oil shale pyrolysis showed that the quality of the oil improved with an increase in the heating rate (asphaltene reduced from ۳۱% to ۲۸ %,  sulfur content reduced from ۱۹% to ۱۳%, and carbon percentage near to constant), while the amount of produced oil diminished from ۴.۷% to ۴.۳% weight of the sample. The grain size of the shale was divided into three ranges: ۷-۱۲ mm, ۷-۴ mm, and less than ۴ mm. In the case of microwave heating, the amount of produced oil increased with the grain size reduction (from ۵.۹% to ۶.۸% weight of the sample). Still, the quality fluctuated (asphaltene reduced from ۲۰% to ۱۸ % then increased to ۲۲%,  sulfur content reduced from ۱۲% to ۱۰% then increased to ۱۵%, carbon content increased from ۷۵% to ۸۰% then reduced to ۶۹%, Aliphatic component increased from ۳۸% to ۴۰.۵% then reduced to ۳۴%, also aromatic index reduced from ۰.۲۸% to ۰.۲۶% then increased to ۰.۳۱%). These results suggest that there is potential for further research to optimize the grain size for oil shale production. With the conventional heating techniques, the quality of the produced oil improved but can also fluctuate with decreases in grain size (from ۴.۷% to ۵.۴% then ۵.۱%). Also, the quality fluctuated (asphaltene reduced from ۳۱% to ۳۰ % then increased to ۳۳%,  sulfur content reduced from ۱۹% to ۱۷% then increased to ۲۰%, carbon content increased from ۶۲% to ۷۱% then reduced to ۶۴%, Aliphatic component increased from ۲۸% to ۳۰% then reduced to ۲۵%, also aromatic index reduced from ۰.۲۹%, to ۰.۴۲% then increased to ۰.۳۶%). It was found that microwave pyrolysis yielded more oil produced than the conventional method and improved the quality of the oil. An optimal particle size and heating rate can be established based on the results, sparking interest in further research to explore these possibilities.

کلیدواژه ها:

Oil Shale ، microwave ، pyrolysis ، shale oil ، Upgrading ، Qalikuh