The effects of pyrolysis conditions on Israeli oil shale properties

Abstract

This paper reports on a study which was undetaken to identify the influence of pyrolysis parameters on the qaulity and quantity of oil from the EF'E oil shale deposit in Israel. Pyrolysis experiments were performed in three reactors which allowed variations in heating rate, bed geometry, pressure, temperature, and residence time of the pyrolysis products. These parameters were varied in a series of pyrolysis tests to identify the controlling mechanisms. The pyrolysis results indicate that high oil yields can be achieved with proper process conditions. Secondary reactions of the oil (cracking and coking) are both minimized when temperature and residence time for oil in the reaction zone are kept to a minimum. When the oil remains in the hot zone, such as in the Fischer Assay, cracking lowers the oil yield and increases light hydrocarbon gases. In addition secondary reactions increase the aromaticity, decrease the nitrogen and increase the sulphur content of the oil. All evidence suggests that the Israeli shale oil is more prone to cracking than a Colorado Green River shale oil on which similar tests were performed. The average molecular weight of the Israeli oil is lower, the rate of evolution is higher and the Fischer Assay oil yield is lower.