Patent ID: 6139720
Filing Date: 2000-10-31
Classification: C10G,Y02P

Abstract:
A process for the fluidized catalytic cracking of hydrocarbons, said process comprising:a) contacting fluidized particles of regenerated FCC catalyst with a hydrocarbon feed at hydrocarbon conversion conditions to convert the hydrocarbons in the feed to lower boiling hydrocarbons and to produce a mixture of FCC catalyst and converted hydrocarbons;b) separating the mixture of FCC catalyst and converted hydrocarbons into a first gaseous effluent for recovery from the process and a separated catalyst carrying adsorbed and/or entrained hydrocarbons;c) passing the separated catalyst to a prefatory stripping zone and contacting the particles with a stripping gas to strip hydrocarbons from the separated FCC catalyst and from the void volume between catalyst particles to produce an initially stripped catalyst and a stripper stream comprising displaced hydrocarbons and stripping fluid that is recovered from the process;d) passing the initially stripped catalyst and regenerated catalyst from a hot regenerated catalyst stream to a heated stripping zone and mixing the initially stripped catalyst and the regenerated catalyst by injecting a fluidizing gas into a first segregated volume of the heated stripping zone to further strip the initially stripped catalyst of additional strippable materials and to produce a heated stripping catalyst;e) infilling a second, and relatively smaller, segregated volume of the heated stripping zone with heated stripping catalyst by withdrawing hot stripped catalyst from the bottom of the second segregated volume and contacting the heated stripping catalyst with a final stripping fluid in the second segregated volume to strip additional strippable compounds from the heated stripping catalyst and to produce the hot stripped catalyst;f) recovering a light gas stream comprising fluidizing gas, stripping fluid, light hydrocarbons and gaseous sulfur and nitrogen compounds from the heated stripping zone;g) injecting a transport fluid into a regenerator transport conduit to withdraw hot stripped catalyst from the bottom of the second segregated volume and to transport the hot stripped catalyst into a regeneration zone;h) discharging a stream of partially regenerated catalyst and gas from the transport conduit into an upper portion of a dense bubbling bed of catalyst contained within a regeneration zone wherein the discharged gas has an oxygen concentration of less than 5 mol %;i) passing an oxygen-containing regeneration gas upwardly through the dense bubbling bed of catalyst to regenerate the catalyst and produce regenerated FCC catalyst for contact with the hydrocarbon feed and the hot regenerated catalyst stream; andj) collecting a flue gas having a CO.sub.2 /CO ratio of at least 1 from the regeneration zone.