Abstract: At present, PetroChina Dushanzi Petrochemical Company mainly processes Kazakhstan crude oil, Karamay Mahu crude oil and South Xinjiang Yaha crude oil, and the designed yield of mixed diesel is 31%. In recent years, the demand for dieselin the market has been decreasing. In order to alleviate the high pressure on the refinery's diesel inventory and the shortage of naphtha directly supplying ethylene unit due to the less volume of the crude oil than before. Some outstanding contributions were made to improving the refinery overall operating efficiency by implementing the adjustment side line pumparound of atmospheric and vacuum distillation units, optimizing the operation of atmospheric distillation tower, which could lead to reducing the yield of straight-run diesel to 26.06% and optimizing the refinery's product distribution and improving the refinery's overall operating efficiency.

Key words: distillation unit, straight-run diesel, atmospheric distillation tower, yield