Abstract: After the application of MIP in 3.0 Mt/a heavy oil catalytic cracking unit in Lanzhou Petrochemical Company of Petrochina in 2019, during the first operation of the unit, in view of the problems existing in the traditional feeding method, such as the discharge of oil vapor from the inlet of the gas compressor, the discharge of non-condensable gas from the reflux tank of the stabilizing tower, the large demand of steam before fuel injection, and the difficulty in raising the temperature outside the closed cover of the settler, an attempt was made to use the riser gasoline injection technique. It was calculated that at least 30 t/h of gasoline was needed to meet the rich gas demand of gas compressor. Gasoline was injected when the temperature at the nozzle of MGD (FCC for maximizing gas and diesel) reached above 530℃, and then the feedstock was injected 3 hours later. It was found in practice that the gasoline injection could effectively reduce the steam consumption, accelerate the temperature rise outside the enclosure of the disengager, and increase the circulation of the catalyst,etc. At the same time, good results had been obtained in controlling torch discharge and optimizing operation of product system, which could provide operating experience for similar MIP unit.

Key words: heavy oil catalytic cracking, start-up, gasoline injection, flare discharge, operation optimization