Novel gas-solid separator for catalytic cracking units having an external riser

1) A gas-solid separation device for the particles contained in a gaz-solid suspension resulting from the external riser of a catalytic cracking unit, in which:

• an upper end of the external riser (2) is connected to the separation device (5) by virtue of the pipe (19) forming substantially an angle of 90° with respect to the riser (2),
• each pipe (4) being connected to an elbow (12) located in a vertical plane in which the particles are separated from the gas and pressed against the wall by centrifugal force, then the separated particles flowing downward in return legs (13), themselves connected to a substantially vertical part (14) which serves to rejoin the two flows of particles coming from the two legs (13), then into the return leg (6), and the gas coming from the external riser (2) being separated from the solid in the elbows (12), being turned around approximately 180° in the legs (13) in order to subsequently proceed toward the chambers (15), themselves connected to the collecting pipe (18) in which the fluidizing/stripping gas coming from the fluidized stripping bed is channeled,
• the gaseous effluents coming from the riser (2) and the gases coming from the downstream fluidized bed being subsequently sent to a cyclone tier (9) via the discharge pipe (16), which device is characterized in that said pipe (19) divides into two tubular sections (4) forming between them an angle 2*γ, γ being between 5° and 85°, preferably between 25° and 65° and in a preferred way between 40° and 50°.