Abstract: To increase the production of high value-added products and improve the benefits,SINOPEC Beijing Yanshan Company made collaborative optimization for the oil refining sector. The medium-pressure hydrocracking unit used a mixed feed blending with FCC diesel fraction, and ran in hydroupgrading scheme instead of hydrocracking, the upgraded diesel was returned to No.3 FCC unit for refining. At the same time, to improve the catalytic cracking feed properties, the CGO was fed into hydrocracking unit and no longer processed in the hydrotreating unit. After collaborative optimization, the cetane number of the medium-pressure hydrocracking diesel was increased by 7 units. The LPG yield of No.3 FCC was increased by about 1.96 percentage points, the gasoline yield was increased by 0.88 percentage points, and the total liquid was increased by 2.28 percentage points. The jet fuel density ( 20℃) of hydrocracking unit was reduced to 806 kg/m3 with a smoke point of 23.8 mm, and the BMCI of tail oil was reduced from 11.8 to 10.8. The saturated hydrocarbons of hydrotreated VGO were increased by 4.68 percentage points with a reduction of 5.96 percentage points of aromatics and 0.06 percentage points of nitrogen content, respectively, resulting in improved FCC feed quality. The jet fuel distillate of the medium pressure hydroupgrading unit was cycled back to FCC unit. Compared with the process of recycling back the upgraded diesel oil, the research octane number (RON) of the catalytic cracking gasoline was increased by 1.0 unit and the cetane number of the upgraded diesel oil was increased by 4.8 units. Through collaborative optimization of the whole refining scheme, the cetane number of vehicle diesel product of Yanshan petrochemical branch was reduced from 53.5 to 51.5, which solved the problem of excess quality.

Key words: process optimization, medium pressure hydrocracking, catalytic cracking, cetane number