New system for gas-solid separation and for stripping for fluidised bed catalytic cracking units

摘要

A device for separating and stripping a gas mixture and a flow of particles, comprises a casing divided into alternating separation and prestripping chambers round vertical central reactor, a lower stripping zone within the casing and at least one external secondary separator with a return leg for particles separated from the gaseous effluent. A device for separating and stripping a gaseous mixture and a flow of particles, comprises a casing (50) divided into several separation chambers (SC) and several pre-stripping chambers (PSC) (3) distributed alternately round a vertical, elongated central reactor (1) closed at the top (15), in which the gas and particles are circulating. Each SC has: (a) an inlet opening at the top communicating with the reactor and with a centrifugation zone enabling separation of the particles by a deflector, the zone being defined for rotating the gas mixture and particles in a vertical plane at an angle of not more than 180[deg]; (b) an external wall, an internal wall joined to the external wall of the reactor and two vertical lateral walls which are also the lateral walls of the PSC, at least one of the lateral walls in each SC having a first lateral communication (5) below the opening which enables the gas mixture to communicate with the adjacent PSC; and (c) a second opening below the lateral communication in the lower part of the PSC, enabling the axial egress of particles and communicating below the SCs with a stripping zone (30) containing at least one main stripping device (11). (d) The casing also has: (e) an outlet pipe (14) for the mixture of gaseous effluents from the PSC, situated on the axis of the reactor and connected to the PSC by the openings (8) at the top; and (f) at least one secondary separator (16) for separating the solid particles in the gaseous effluent from the outlet pipe, the secondary separator comprising an outlet (9) for gaseous effluents and an outlet (17) for particles descending into the stripping zone which communicates with the outlet pipe via openings (7) at the bottom of the PSC. An independent claim is included for the catalytic cracking of hydrocarbons in a fluidized bed using the device described above.