Abstract: Based on the operation data of the heavy oil coking unit in Karamay Petrochemical Company, a comparison of heavy oil direct coking process and distillation-coking combine process was carried out. It can be seen that as compared with the combine process, heavy oil direct coking technology exhibited less investment, more cracking of VGO fractions and higher diesel to gasoline ratio, yet higher yields of coke and gas were observed. Because atmospheric tower was omitted in the heavy oil coking unit, energy consumption of the unit and the operation cost in subsequent processes became higher. Since naphthenic acid could be decomposed at high temperature in coke tower, a new idea about anti-corrosion of naphthenic acid was presented and discussed in this paper as well. For reducing energy consumption and saving downstream processing fee, a suggestion of adding an atmospheric distillation tower in the coking unit, adopting indirect heat exchange for residue coking and using carbon steel instead of 316L steel in the distillation system was proposed based on the above analysis. Furthermore, adding a coker gatch stripper could significantly improve the separation of coker gas oil from coker gatch, resulting in less downstream processing fee, and this was realized in this existed unit.

Key words: Crude oil, Coking, Anti-corrosion, separation