Patent ID: 7041259

Claim:
An apparatus for the fluidized catalytic cracking of hydrocarbons, the apparatus comprising: a reaction zone in which blended catalyst is contacted with a hydrocarbon feed; a separator vessel for receiving effluent from said reaction zone and separating said effluent into a vapor product and spent catalyst; a recycled catalyst conduit communicative with said separator vessel for passing spent catalyst to said reaction zone, said recycled catalyst conduit including a recycled catalyst control valve for regulating spent catalyst circulation and instrumentation for determining the circulation rate of spent catalyst through said recycled catalyst conduit; a regeneration zone for removing carbon from said spent catalyst to provide regenerated catalyst; a spent catalyst conduit communicative between said separator vessel and said regeneration zone for passing spent catalyst to said regeneration zone; a regenerated catalyst conduit communicative between said regeneration zone and said reaction zone for passing regenerated catalyst from said regeneration zone to said reaction zone, wherein said regenerated catalyst is blended with said spent catalyst to provide said blended catalyst, said regenerated catalyst conduit including instrumentation for determining the circulation rate of regenerated catalyst through said regenerated catalyst conduit; and a recycle catalyst controller for setting a position of the recycle catalyst control valve dependent on whether a relationship between the circulation rate of spent catalyst through said recycle catalyst conduit and the circulation rate of regenerated catalyst through said regenerated catalyst conduit meets a preset condition.