FLUIDIZED CATALYTIC CRACKING

摘要

The present invention relates generally to fluidized catalytic cracking. More particularly, the present invention relates to a baffle arrangement that improves separation of gaseous hydrocarbon reaction products from catalyst within the reactor vessel of a fluidized catalytic cracker unit. The catalytic reactor vessel includes an outer generally cylindrical shell having a stripping zone arranged at the lower end of the vessel. An inlet riser conduit forming a primary reaction zone extends generally within the shell from the lower end of the vessel to a location near the top of the vessel. A shroud surrounds the upper end of the riser conduit and forms an annular outlet for downwardly discharging a mixture of hydrocarbon and catalyst. According to the present invention, an annular catalyst disengaging riser baffle for deflecting the mixture from the outlet toward the wall of the vessel in arranged on the outside of the riser conduit below the annular outlet above the stripping zone. Still further, in the preferred embodiment an annular catalyst disengaging wall baffle is arranged on the inside of the shell for again deflecting the mixture, now mostly catalyst, generally downwardly and toward stripping the zone of the vessel. Preferably, the riser baffle and the wall baffle are arranged within the shell such that the baffles in concert with the annular discharge outlet form a partial cyclone separating zone between the baffles to thereby improve the separation of hydrocarbon vapors from the catalyst. This cyclone action promotes early disengagement of hydrocarbon vapor from the catalyst and reduces undesirable catalyst carryover in the vapor to conventional cyclones through which the hydrocarbon to conventional cyclones through which the hydrocarbon products are recovered. At the same time, stripping efficiency is also increased by quickly and effectively delivering spent catalyst to the stripping zone and undesirable secondary cracking reactions in the dilute phase are minimized by lowering the concentration of spent catalyst in the dilute phase.