Abstract: A company has carried out the production practice of mixing vacuum residue(VR)into a 2.2 Mt/a deep catalytic cracking (DCC) unit. After mixing VR, the effect of mixed feed quality deterioration on product distribution, product properties, operating parameters, catalyst consumption, energy consumption and long-term stable operation of the plant was comprehensively analyzed, and corresponding countermeasures were taken. The results show that the raw material quality of DCC is improved by changing the raw material of upstream unit to medium/light crude oil. By optimizing the mixing ratio of DCC unit feed, adjusting the operating parameters of DCC unit, increasing the dosage of metal passivator,increasing the amount of catalyst replacement and other countermeasures, the increase of coking tendency of the unit caused by the increase of raw material carbon residue and the adverse effects of heavy metals such as Ni, Ca, Fe,and so on,were weakened, creating a precedent for the mixing VR of similar units,which can ensure the safe and smooth operation of the device. When the VR blending ratio (w) reached 44.4%, the total liquid yield decreased by 1.61 percentage points, the coke yield increased by 1.87 percentage points, and the energy consumption increased by 230.903 MJ/t.

Key words: deep catalytic cracking, vacuum residue, feedstock optimization, catalyst, calcium