Patent ID: 7195741

Claim:
A hydrocarbon conversion apparatus comprising: a plurality of riser reactors, each of said riser reactors having a first end into which a catalyst can be fed and a second end through which the catalyst can exit said riser reactor; a mouth in which each riser reactor terminates and through which catalyst and feed are fed into the riser reactors; a plurality of necks for providing feed to an associated riser reactor, wherein each neck terminates in a head and each head of each neck is positioned adjacent to the first end of each riser reactor and each head is positioned at or above the mouth; a separation zone into which said second ends of said riser reactors extend, said separation zone being provided to separate the catalyst from products of a reaction conducted in said hydrocarbon conversion apparatus; a catalyst return connecting said separation zone and said catalyst retention zone to transport catalyst from the separation zone to the first ends of the riser reactor; and a catalyst retention zone defined by the catalyst return and a first end of the riser.