Abstract: Marine fuel oil is mainly produced by blending vacuum residue, hydrotreated residue, FCC slurry and FCC diesel oil, and its pour point and viscosity are reduced by thermal upgrading of high viscosity components, which can reduce the amount of light blending components, optimize the production formula and reduce the production cost of marine fuel oil. W refinery planned to use atmospheric residue as low sulfur marine fuel product. Through the application of atmospheric and vacuum distillation and thermal upgrading combination process, the lab-scale results showed that the kinematic viscosity（50 ℃） of vacuum residue with appropriate cutting point could be reduced to less than 380 mm²/s. Selecting low sulfur blending components can release the whole straight-run diesel and VGO fractions and reduce the production cost of marine fuel oil. The marine fuel through the application of thermal upgrading and blending combination process was directly produced by using blending vacuum residue, preferred heavy oil F and FCC diesel oil as raw materials in H refinery. The pilot test results showed that the viscosity and pour point of vacuum residue were greatly decreased, the amount of blended diesel could be reduced by 50%, and the economic benefits of the refinery could be greatly improved.

Key words: low sulfur marine fuel oil, processing scheme, upgrading, visbreaking, blending, low cost