Abstract: The effect of reducing operating pressure on delayed coking process was studied. The pilot test results showed the yield of liquid and gas oil increased by 2.03 and 4.64 percentage points, respectively, while the yield of gas and coke decreased when the operating pressure of coker drum was reduced from 0.195MPa to 0.115MPa under the basically same conditions of the outlet temperature of delayed coking furnace, steam injection amount and recycle ratio. With the decrease of operating pressure, the properties of coker gasoline and coker diesel oil changed little, but coking gas oil properties became worse, mainly in increases of density, carbon residue asphaltene and nitrogen content, metal content, while the distillation range 95% point temperature increased by 14℃and the volatile component decreased.

Key words: delayed coking, operating pressure, liquid yield, product property, volatile component