Simulation, exergy analysis and optimization of a shale oil hydrogenation process for clean fuels production

Because of high contents of unsaturated hydrocarbons, sulfur, nitrogen and other impurities in shale oil, its potential use as an alternative fuel is limited. Shale oil hydrogenation technology is an efficient technique for upgrading shale oil to remove heteroatomic compounds. The whole shale oil hydrogenation process is modeled and simulated firstly in this paper, including embedding the kinetic models of hydrogenation reactions. The corresponding-state group contribution method is applied to estimate the physical properties of the components of shale oil. The performance of the shale oil hydrogenation process is analyzed by exergy analysis. The results indicate that the exergy efficiency of the shale oil hydrogenation process is about 69.20%. The energy bottleneck is the furnaces and compressors because the energy consumption of these devices is 59% and 24% of that of the shale oil hydrogenation process. Furthermore, to optimize the performance of this process, the key parameters of the process are investigated and optimized. The preferable reaction temperature of the hydrorefining and the hydrocracking reactors is 350-375 °C and 375-400 °C. The reaction pressure and catalyst grading ratio are suggested to 16-17 MPa and 1:3:3 for maximizing the yield of products with ultra-low nitrogen and heteroatomic compounds.