The mechanism and cause of the formation of the fouling deposit in the feed heat exchanger of the hydrocracking unit in Shengli Refinery were proposed after the analysis of the deposit.

Considering the high contents of olefins and nitrogen, the whole fraction of delayed coker distillates (including light and heavy naphtha, gas oil) must be hydrotreated.

Commercial application of a combination technology, solvent deasphalting with hydrotreating of VGO blending DAO and gasification of asphalt, was introduced.