Patent ID: 6689845
Filing Date: 2004-02-10
Classification: B01J,C08F,Y10S

Abstract:
A process for the catalytic polymerization in the gas-phase carried out in at least two interconnected polymerization zones, the process comprising feeding one or more monomers to said polymerization zones in the presence of catalyst under reaction conditions and collecting the polymer product from said polymerization zones, in which process the growing polymer particles flow upward through one of said polymerization zones (riser) under fast fluidization or transport conditions, leave said riser and enter another polymerization zone (downcomer) through which they flow downward under the action of gravity, leave said downcomer and are reintroduced into the riser, thus establishing a circulation of polymer between the riser and the downcomer, wherein:means are provided which are capable of totally or partially preventing the gas mixture present in the riser from entering the downcomer, and a gas and/or liquid mixture having a composition different from the gas mixture present in the riser is introduced into the downcomer.