Patent ID: 6887954

Claim:
A process for the gas-phase polymerization of olefin(s) in a fluidized-bed reactor, comprising feeding a fluidized-bed reactor with olefin(s) and with catalyst, maintaining solid particles of polymer formed and of the catalyst in a fluidized state within the reactor by the action of an ascending gas stream containing the olefin(s), starting from a base of the reactor and rising up to a top part thereof, withdrawing a recycling gas stream containing unreacted gases and entrained solid particles from the top part of the reactor, moving the recycling gas stream with a compressor, cooling the recycling gas stream by passing the recycling gas stream into a multitubular heat exchanger successively having an inlet chamber, a bundle of tubes with a horizontal longitudinal axis and an outlet chamber equipped with a discharge orifice, accelerating the flow of the recycling gas stream in the outlet chamber up to the discharge orifice, directing the flow of the recycling gas stream at any point in the outlet chamber of the heat exchanger along a horizontal axis and/or towards a bottom part of the outlet chamber so as to create in the bottom part a sweeping stream that flows horizontally or with a downward inclination and without obstruction up to the discharge orifice to promote entrainment of the solid particles therein up to the discharge orifice, and reintroducing the cooled recycling gas stream from the discharge orifice of the heat exchanger at the base of the reactor.