Study on pyrolysis of ultra-high-quality oil shale: product characterization and a utilization process

Abstract

ABSTRACT Nantun (NT) oil shale of ultra-high oil yield (>30%) is rare in the world, while the characteristics of this kind of oil shale are not widely reported. An oil shale pyrolysis experiment has been conducted in a tube furnace. The products of gas, oil and char are collected and analyzed on their yield and properties in the range of 450 to 650°C. The oil yield remained above 30% in the range of 450 to 550°C and decreased rapidly from 30.84% to 9.35% at 550 to 650°C. The char yield drops from 66.14% to 57.94% as the pyrolysis temperature increases, and aliphatic hydrocarbon components in char have been cracked completely at 450°C. The yield of pyrolysis gas rises as the pyrolysis temperature increases. CO accounts for the largest proportion of pyrolysis gas, with a volume fraction of over 70%. Based on the characteristics of pyrolysis products, an ultra-high-quality oil shale pyrolysis and utilization process and an Aspen Plus simulation model have been developed that provides estimated material and energy equilibriums for an industrial self-sustaining pyrolysis process to produce char and shale oil. This process can produce 0.61 kg oil and 0.29 kg char per kilogram of oil shale under self-sustaining conditions at 500°C. In practical applications, the pyrolysis temperature is recommended to be 500°C.