Patent ID: 7727380

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 at least a portion of a regeneration gas stream containing oxygen to said coked catalyst; combusting coke on said coked catalyst with oxygen to regenerate said catalyst and provide flue gas; separating said gaseous product hydrocarbons to obtain a plurality of product streams including a selected product stream; delivering said selected product stream to an expander; expanding the volume of said selected product stream in said expander; recovering power from said selected product stream in said expander; And then combining at least a portion of said selected product stream with at least a portion of said regeneration gas stream.