Patent ID: 7686944

Claim:
A process for processing streams from a fluid catalytic cracking unit comprising: contacting cracking catalyst with a hydrocarbon feed stream to crack the hydrocarbons to gaseous product hydrocarbons having lower molecular weight and deposit coke on the catalyst to provide coked catalyst; separating said coked catalyst from said gaseous product hydrocarbons; adding oxygen to said coked catalyst; combusting coke on said coked catalyst with oxygen to regenerate said catalyst and provide flue gas; separating said catalyst from said flue gas to provide a flue gas stream; separating said gaseous product hydrocarbons to obtain a plurality of product streams including a selected product stream; adding oxygen to said selected product stream; combusting said selected product stream with oxygen; combining at least a portion of said selected product stream with at least a portion of said flue gas stream to provide a combined stream; delivering said combined stream to an expander; expanding the volume of said combined stream in said expander; and recovering power from said combined stream in said expander.