Patent ID: 8491781

Claim:
A process for producing propylene from a heavy catalytic cracking feed and at least one light feed constituted by a light gasoline (C5-150° C.), in a reaction zone, said process comprising: in a principal riser ( 10 ) of a principal reactor ( 100 ), conducting catalytic cracking of said heavy feed; in one or more additional risers ( 210 ), operating at higher severity than the principal riser ( 10 ), conducting catalytic cracking of light feeds including said at least one light feed constituted by a light gasoline (C5-150° C.), said additional riser or risers ( 210 ) operating in parallel with the principal riser ( 10 ), and passing resultant gaseous and solid effluents from said additional riser or risers ( 210 ) to a dilute zone ( 110 ) located in an upper part of the principal reactor ( 100 ), introducing a quench fluid into said dilute zone ( 110 ) of said principal reactor ( 100 ) to quench effluents from said principal riser, and introducing a flush fluid into an upper part of said dilute zone ( 110 ) to flush said dilute zone, wherein: a) at least 70% by weight of said quench fluid ( 230 ) is injected into the principal reactor ( 100 ) with effluents ( 221 ) from said additional riser or risers ( 210 ); and b) at least 70% by weight of said flush fluid ( 104 ) is made up of reaction effluents ( 221 ) derived from said additional riser or risers ( 210 ), c) a temperature (T 5 ) of the dilute phase in said dilute zone ( 110 ) of said principal reactor ( 100 ) is 490° C. to 520° C., d) a residence time of materials in the principal reactor ( 100 ), measured from introduction of the heavy feed into the bottom of the principal riser ( 10 ) to the discharge of reaction effluents from the principal reactor ( 100 ), is less than 10 seconds, and e) said at least one light feed constituted by a light gasoline (C5-150° C.) contains at least 30% by weight olefins.