Patent ID: 6187878
Filing Date: 2001-02-13
Classification: C08F,Y10S

Abstract:
A continuous gas-phase fluidised bed process for the polymerisation of olefin monomer selected from the group consisting of (a) ethylene, (b) propylene, (c) mixtures of ethylene and propylene, and (d) one or more other alpha-olefins mixed with (a), (b) or (c), in a fluidised bed reactor, said process comprising withdrawing a gaseous stream from the reactor containing at least some of the ethylene and/or propylene, continuously recycling the gaseous stream through the fluidised bed in said reactor in the presence of a polymerisation catalyst under reactive conditions, and dividing said recycling gaseous stream withdrawn from said reactor, before the stream is introduced into the reactor, into two streams, wherein(a) a first stream (A) is cooled to a temperature at which liquid condenses out is then introduced directly into the fluidised bed in the reactor in such a way that, at any time, said condensed liquid is continuously introduced into said bed at a minimum rate of 10 liters of liquid per cubic meter of fluidised bed material per hour, and(b) a second stream (B), which by-passes the above cooling/condensing step, is passed through an exchanger and is then introduced into the reactor.