FCC apparatus with short primary contacting and controlled secondary contacting

An apparatus for the fluidized catalytic cracking of hydrocarbons, said apparatus comprising:

• a) a disengaging vessel having a first diameter and defining a primary feed inlet in its sidewall;
• b) a riser conduit defining a riser inlet in communication with the interior of said disengaging vessel at one end and an outlet at its opposite end, said riser conduit having a second diameter that is smaller than said first diameter, said riser inlet located below said primary feed inlet and a fluidizing gas nozzle located proximate said riser inlet;
• c) a regenerator vessel in communication with a first standpipe conduit for supplying regenerated catalyst to said primary feedstream inlet;
• d) means for mixing regenerated catalyst from said first standpipe conduit with carbonized catalyst and injecting the mixture of regenerated and carbonized catalyst along with a primary feedstream into said primary feed inlet;
• e) a primary product outlet defined by said disengaging vessel at a location above said primary feed inlet;
• f) a first separator for receiving a primary product stream from said disengaging vessel, separating carbonized catalyst from said primary product stream and returning carbonized catalyst to said disengaging vessel via a first recycle conduit;
• g) a second separator for receiving a secondary product stream from said riser and separating carbonized catalyst from said secondary product stream and passing carbonized catalyst to a stripping vessel;
• h) a second standpipe conduit for passing carbonized catalyst from said stripping vessel to said disengaging vessel;
• and,
• i) means for passing carbonized catalyst particles to said regenerator to regenerate catalyst particles.