Polymerisation process
First Claim
1. 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in the presence of a polymerisation catalyst under reactive conditions, and dividing said recycling gaseous stream withdrawn from said reactor, before the stream is introduced into the reactor, into two streams, wherein(a) a first stream (A) is cooled to a temperature at which liquid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.
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Accused Products
Abstract
A continuous gas fluidized bed process for the polymerization of olefin monomer(s) wherein the recycled gaseous stream withdrawn from the reactor is divided into two streams (A and B) and that (a) a first stream (A) having been cooled to a temperature at which liquid condenses out is then reintroduced directly into the fluidized bed in the reactor in such a way that, at any time, the condensed liquid is continuously introduced into the bed at a minimum rate of 10 liters of liquid per cubic meter of fluidized 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 reintroduced into the reactor. The continuous introduction of a liquid into the reactor reduces or even eliminates fouling problems which can be encountered in conventional gas phase olefin polymerization processes.
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Citations
9 Claims
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1. 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.
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6. A start-up process of 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.
Specification