PROCESS AND APPARATUS FOR THE GAS-PHASE POLYMERISATION

摘要

A process for the gas-phase catalytic polymerization carried out in two interconnected polymerization zones, to which one or more monomers are fed in the presence of a catalyst under the polymerization conditions and from which the produced polymer is discharged. The growing polymer particles flow through a first polymerization zone under fast fluidization conditions, leave said first zone and enter a second polymerization zone through which they flow in a densified form under the action of gravity, leave said second zone and are reintroduced into the first polymerization zone, thus establishing a circulation of polymer between the two polymerization zones. The present invention is characterized in that a gas of composition different from that present in the first polymerization zone is introduced into the second polymerization zone and it is avoided that the gases present in the first polymerization zone are introduced into the second polymerization zone. The process is particularly suited for obtaining in-reactor made blends of olefin polymers having different compositions. 22 claims, 4 figures