Abstract: Under the consistent conditions of the outlet temperature of heating furnace, the operating pressure of coking tower and the evaporation zone temperature of fractionator, CNPC Dushanzi refinery reduced the circulation ratio of the unit from 0.4 to 0.13 by technique of partially circulating oil. The measures increase the wax oil by 9.44 percentage points and the total liquid yield by 2.96 percentage points, the yield of diesel, gasoline and coke is decreased by 3.37, 2.38 and 1.98 percentage points, respectively while the energy consumption is lowered by 221.95 MJ/t.

Key words: delayed coking, circulation ratio, energy consumption, liquid yield