Abstract: The RFCC unit of Qingdao Petrochemical Company was revamped to conduct MIP operation mode, yet the temperature of the 1st reaction zone in the riser was fluctuated badly after revamping. Investigation on the equilibrium catalyst (E-cat) properties and observation on the fluidization and cycle of regenerated catalyst indicated that high E-cat density and insufficient send-out force caused unstable flow of regenerated catalyst, which significantly affected the pressure drop of regeneration slide valve and the reaction temperature. Countermeasures for enhancing the send-out force of cycle the regenerated catalyst were adopted, the catalyst flow became stable, and less fluctuations of slide valve pressure drop and reaction temperature were observed. The total liquid yield increased by 0.85 percentage point with this smooth operation.

Key words: catalytic cracker, temperature, modification