CLOSED FCC CYCLONE SYSTEM

The present invention involves a fluid catalytic cracking (FCC) apparatus and process comprising a reactor riser zone, primary and secondary cyclones, connected in series to the riser zone, and a stripping zone. The riser zone, the primary and the secondary cyclones, and the stripping zone, are placed within a single reactor vessel. The primary cyclone is connected to the reactor riser zone by an enclosed conduit which prevents random post-thermal cracking of the hydrocarbons after they exit the reactor riser zone. The secondary cyclone is also connected to the primary cyclone by an enclosed conduit. Any one or both of the enclosed conduits contain a trickle valve to accommodate sudden increased surges of pressure and of flow of the hydrocarbons and catalyst mixture. The reactor riser zone is equipped with an opening which allows stripping gases, from the stripping zone, to enter the riser. The gases can be subsequently conducted through the primary and secondary cyclones to the downstream fractionation means.