Research on the reaction mechanism and modification distance of oil shale during high-temperature water vapor pyrolysis

Abstract

When oil shale is pyrolyzed with high-temperature water vapor as a heat carrier fluid, the water vapor will participate in the pyrolysis reaction of organic matter, to change the release characteristics of oil and gas products. Based on the self-designed long reaction system of oil shale pyrolysis by injecting water vapor, this paper deeply studies the quantitative law of water vapor temperature and reaction distance on oil upgrading, compares the quality of shale oil using different pyrolysis methods, and reveals the mechanism of upgrading of oil shale pyrolysis by injecting water vapor. The change of heteroatom and light component contents of shale oil can indicate the change in shale oil quality. The relationship between the two indexes and the reaction distance follows the Boltzmann distribution, and the relationship is called the modification distance. When the injection temperature is 450 °C, the modification distance of shale oil is 1400 mm. When the injection temperature reaches 500 °C, the modification distance extends to 2600 mm. Moreover, when the temperature of the water vapor is low, the reaction intensity is low, the upgrading level is low, and the modification distance is short. However, when the temperature of the water vapor is high, the shale oil's rapid hydro-upgrading distance increases, and the upgrading degree is also enhanced. To make oil shale fully pyrolyzed and form shale oil with good quality, the injection temperature should be at least 500 °C. In that case, the reaction distance of 2600 mm is the threshold distance of oil upgrading. The light component content in the shale oil obtained by the pyrolysis of oil shale with water vapor can be two times that obtained by direct distillation and three times that of crude oil.