Abstract: In order to improve the quality of the diesel in the whole plant and co-processing the high proportion of FCC light cycle oil, SINOPEC Maoming Comany retrofitted the No. 4 diesel hydrogenation unit to carry out the technical transformation calibration. The calibration results showed that the new upgrading reactor, adjustment of the catalyst gradation, modification of fractionation column tray number, and the addition of new light diesel side-line stripper were adopted, the revamped unit was operated under the conditions of diesel blending ratio of 26.5%, inlet pressure of refined reactor of 8.55 MPa, inlet temperature of the refining reaction of 312.5 ℃ and inlet temperature of upgrading reactor of 358.0 ℃ , the cetane index was 49.1, which was 5.7 higher than that of the feedstock, and the energy consumption was 293.52 MJ/t, which was obviously superior to the design energy consumption of the unit. The quality of the refined diesel with sulfur content of less than 10 μg/g and polycyclic aromatic hydrocarbon content of less than 7% could be obtained. At the same time, there were still some the problems in the operation of the unit, which need to further optimize the raw material composition of the unit and reduce the frequency of raw material switching.

Key words: catalytic cracking, light cycle oil, hydrogenation, cetane number