Systems and processes for fluidized catalytic cracking (fcc)

A fluid catalytic cracking system comprising:

• a stripper vessel having a spent catalyst outlet;
• a first regeneration stage downstream from the spent catalyst outlet and configured and adapted to regenerate a spent catalyst from the stripper vessel;
• a second regeneration stage downstream from the first regeneration stage, the second regeneration stage configured and adapted to fully regenerate a partially regenerated catalyst from the first regeneration stage, wherein the second regeneration stage is in fluid communication with the stripper vessel;
• and
• a riser reactor upstream from the stripper vessel and in fluid communication with the second regeneration stage, the riser reactor configured and adapted to receive a first portion of a fully regenerated catalyst from the second regeneration stage, wherein the stripper vessel is configured and adapted to receive a spent catalyst from the riser reactor and a second portion of a fully regenerated catalyst from the second regeneration stage to mix with the spent catalyst for better stripping efficiency and prompting further reactions.