Patent ID: 7351326
Filing Date: 2008-04-01
Classification: B01D,C10G

Abstract:
1. A fluid catalytic cracking process comprising: (a) cracking a crackable hydrocarbon feed by contact with a source of regenerated fluidized cracking catalyst in an enclosed conduit cracking reactor to produce a mixture of cracked hydrocarbon products and spent catalyst containing coke and strippable hydrocarbons and discharging said mixture directly into a closed cyclonic separation means within a vessel; (b) cyclonically separating said mixture in said separation means into a cracked hydrocarbon product vapor phase with a reduced catalyst content relative to said mixture discharged from said cracking reactor and a spent catalyst phase containing coke and strippable hydrocarbons; (c) discharging said spent catalyst phase down from said cyclonic separation means into a catalyst stripper within said vessel, said stripper having an upper portion with a stripper cross sectional area, said stripper being in open fluid communication with said vessel and at least a majority of said stripper cross sectional area is open to said vessel; (d) stripping said spent catalyst in said catalyst stripping means by maintaining spent catalyst as a dense phase fluidized bed fluidized at least in part by injection of stripping steam into a lower portion of said bed to produce: stripper vapor which is discharged up from said dense phase fluidized bed in said stripping means into said vessel, and stripped catalyst which is discharged from said stripping means into a catalyst regenerator; (e) regenerating said stripped catalyst in said catalyst regenerator at catalyst regeneration conditions including contact with an oxygen containing gas and burning coke from said stripped catalyst to produce regenerated catalyst which is recycled to said cracking reactor to crack said feed; and (f) recovering said stripper vapor discharged up from said dense phase fluidized bed in said stripping means via a snorkel comprising a vertically extending transfer conduit having: an inlet in said upper portion of said stripper above said dense phase fluidized bed of spent catalyst in said stripper, and an outlet connective with said cyclonic separation means and wherein said closed cyclonic separation means comprises: at least one primary cyclone sealingly affixed to said reactor outlet and receiving spent catalyst and cracked products discharged from said riser, discharging spent catalyst down via a primary cyclone dipleg into said stripping means and discharging vapor with a reduced spent catalyst content via a primary cyclone vapor outlet line; and secondary cyclones further separating spent catalyst from vapor and discharging spent catalyst down via a secondary cyclone dipleg into said stripping means and discharging vapor with a further reduced spent catalyst content via a secondary cyclone vapor outlet directly into a transfer line to a product fractionation means, and said vertically extending conduit transfers stripper vapor from said stripper to said primary cyclone vapor outlet and wherein at least a portion of said vertically extending transfer conduit is within said primary cyclone dipleg.