Abstract: In order to better understand the influence of the ratio of hydrogen to oil on diesel hydrotreating process and improve the operation cycle and production benefit of the unit by optimizing the process parameter, the mixture oil of straight run diesel and catalytic cracking diesel from multiple refineries was used as feedstock. The hydrodesulfurization performance of diesel, the saturation performance of polycyclic aromatic hydrocarbons and monocyclic aromatic hydrocarbons and the effective utilization rate of hydrogen were investigated. By adding polycyclic aromatic phenanthrene to the feedstock, the reaction performance of the feedstock was investigated, and the reason of increasing the ratio of hydrogen to oil to improve the reaction performance was analyzed. The results show that increasing the ratio of hydrogen to oil can improve the atomization effect of feedstock, further promote the desulfurization and polycyclic aromatic hydrocarbon saturation reaction, and China Ⅵ diesel can be produced at lower reaction temperature, so as to prolong the operation cycle of the unit. At the same time, high ratio of hydrogen to oil can inhibit the saturation of monocyclic aromatic hydrocarbons to a certain extent, reduce hydrogen consumption, so as to improve the effective utilization rate of hydrogen.

Key words: the ratio of hydrogen to oil, ultral deep hydrodesulfurization, polycyclic aromatic hydrocarbon saturation, effective utilization rate of hydrogen