Patent ID: 9181367
Filing Date: 2015-11-10
Classification: C08F

Abstract:
1. Process for operating a vertical fixed bed degasser which is continuously fed with an active polymer powder produced by a catalytic olefin polymerisation process in a polymerisation reactor wherein the polymerisation conditions in the degasser are such that there is produced an additional amount of polymer corresponding to between 0.001 and 0.015 times the amount which entered the degasser, the degassing process comprises the introduction into said degasser of a stripping gas comprising from 5 to 60% by volume of principal monomer, and the degassing conditions are selected such that the temperature inside the degasser is maintained within a range of temperatures comprised between the polymerisation reactor temperature plus or minus 20 degrees centigrade, and further wherein at least one of the following applies: a) the degassing process comprises the introduction into said degasser of at least one polymerization deactivating agent and the selection of the degassing conditions comprises the control of the content of the said deactivating agent, or b) the gas exiting the degasser is introduced in to a vent recovery unit which comprises refrigeration, compression and purification stages which allow separating the gas exiting the degasser into a gas/liquid stream which can be recycled in the upstream operations and the stripping gas stream which can then be used in the degasser, the stripping gas stream consisting essentially of a mixture of inert gas and principal monomer gas.