Patent ID: 7611622
Filing Date: 2009-11-03
Classification: C10G

Abstract:
1. A fluid catalytic cracking (FCC) process for converting a C 3 /C 4 -rich feed to olefins and aromatics, comprising: cracking a first hydrocarbon feed comprising heavy hydrocarbons having greater than 12 carbon atoms in a first riser under first-riser FCC conditions to form a first effluent enriched in cracked hydrocarbons, wherein the first-riser FCC conditions include a residence time from 0.1 to 10 seconds; cracking a second hydrocarbon feed comprising light hydrocarbons having 12 or less carbon atoms, in a second riser under second-riser FCC conditions to form a second effluent enriched in light olefins and aromatics, wherein the second-riser FCC conditions have a higher severity than the first-riser FCC conditions and include a residence time from 0.1 to 10 seconds and a temperature from 510° C. to 710° C. (950° F. to 1300° F.), wherein the first riser and the second riser contain gallium-promoted alumina catalyst; recovering the catalyst from the first riser and the second riser; separating hydrocarbons including light olefins and aromatics from the first and second FCC effluents, wherein the second hydrocarbon feed further comprises a recycle stream comprising propane recovered from the separated hydrocarbons; regenerating the recovered catalyst by combustion of coke in a common regenerator to obtain hot, regenerated catalyst; and recirculating the hot regenerated catalyst to the first and second risers.