Abstract: The capacities of hydrogen supply and hydrogen abstraction of hydrocracking tail oil and vacuum residue from CNOOC refining branch in Huizhou refinery were determined. The delayed coking laboratory and pilot plant test were performed using the residue and the residue with 10% hydrogen cracking tail oil. The pilot plant test results show that at the conditions of 500 ℃ and 0.15 MPa, compare with residue only, the total yield of naphtha, diesel and waxy oil increases 4.2 percentage points; the yield of coke and dry gas reduces 3.1 and 1.1 percentage points，respectively after the addition of hydrocracking tail oil as hydrogen donor.

Key words: delayed coking, hydrogen donor, hydrocracking tail oil, pilot plant test