Abstract: Based on the comparing the operating parameters and coking situations in the first and second operating cycles of the 2.0 Mt/a FCC unit of SINOPEC Yangzi Petrochemical Co. Ltd., the causes of the coking in disengager were analyzed. It was determined that the coking in the disengager is caused by poor cyclone matching and the long oil and gas retention time in the disengager. For this reason, the soft connection of the disengager was changed to a direct coupled plus overflow bucket configuration. The results showed that the disengager coking was effectively avoided, while reducing the dry gas, diesel and coke yields by 0.26, 0.25 and 0.54 percentage point, respectively. The yield of LPG, gasoline and slurry was increased by 0.54, 0.33 and 0.18 percentage point, respectively. The solid content of the slurry was reduced from 4.1 g / L to 2.0 g / L, showing excellent anti-coking and improved operating effects.

Key words: FCC, coking, direct connection, anti-coking