Abstract: An apparatus and method for processing different feeds in a fluid catalytic cracking unit are disclosed which result in improved yields of C3, C4 and gasoline range hydrocarbons as compared to conventional systems. The process comprises injecting a main hydrocarbon feed into a catalyst-containing riser reactor through a plurality of main feed injectors, and injecting a light hydrocarbon feed into the riser reactor at a location upstream from the main feed injectors and downstream from a control valve such as a regenerated catalyst slide valve, the light feed being injected in a region having a high density of catalyst particles. The light feed is injected in a dispersed way such the amount of feed injected corresponds to the density of catalyst particles at that particular point, with greater amounts of feed being injected at locations having a large number of catalyst particles.

Abstract: A process for the fluid catalytic cracking of hydrocarbons includes contacting relatively heavy hydrocarbons with a fluidized particulate catalyst in a reaction zone under catalytic cracking conditions to convert at least some of the heavy hydrocarbons to light olefins having from 3 to 4 carbon atoms, conveying a reaction mixture containing spent catalyst particles and a gaseous stream containing the light olefins and other reaction products to a cyclone separation system directly connected to the reaction zone, at least part of the cyclone separation system being positioned within an interior space enclosed by a vessel, the interior space including a stripping region and an upper region in which the cyclone separation system is positioned. The cyclone separation system includes at least one cyclone connected directly to the reaction zone and having an interior pressure at least 0.05 psig lower than the pressure in the stripping region.