Abstract: In view of the mixed waste oil with light, heavy and active chemical properties in the tank farm of a refining and chemical enterprise, the mixed waste oil was reprocessed in the furnace system of the delayed coker. The difficult problem of treating mixed waste oil was solved by the optimizing the technological process and analyzing the effect after putting into use. The results showed that after refining the mixed waste oil the yield of diesel increased by 2.59 percentage points, and the monthly average efficiency increased by 2.2807 million Yuan. The implementation of the mixed waste oil refining project of delayed coker is an exploratory innovation in the light oil treatment process of heavy oil unit, which has certain reference significance for the processing of ethylene tar in coker.

Key words: delayed coker, furnace, mixed waste oil, return, pipe flow rate, yield, economic benefit