Abstract: A new 2200 kt/a unit adopting DCC-plus technology developed by Research Institute of Petroleum Processing SINOPEC, was set in CNOOC Ningbo Daxie Petrochemical Limited Company. There were some problems met at the initial stage of the unit: lower yields of ethylene and propylene than the design value due to the outsourcing e-cat for start-up and the feed qualities deviate from the design requirement. The ethylene and propylene yields are increased to 4.53w% and 19.52w%, respectively by means of optimizing operating parameters, ratio of feed composition and catalyst formula. These results meet the design requirements of DCC-plus unit and thus make the downstream ethylbenzene-styrene unit run at full capacity.

Key words: DCC-plus, ethylene, propylene, optimization