| 摘要 |
<p>An improved process for the polymerisation of olefin monomer selected from (a) ethylene, (b) propylene, (c) mixtures of ethylene and propylene and (d) mixtures of (a), (b) or (c) with one or more alpha-olefins in a fluidised bed gas phase reactor, said process comprising passing a gaseous mixture of said olefin monomer(s) through the fluidised bed under effective polymerisation conditions to provide a polymer product containing unreacted monomer(s) and a gaseous effluent stream comprising unreacted monomer(s), removing the polymer product to a degassing vessel, recycling a first portion of the gaseous effluent stream to the fluidised bed and passing a second portion of the gaseous effluent stream to counter currently contact the polymer product in said degassing vessel to produce a polymer product having a reduced amount of unreacted monomer(s), characterised in that the improvements to the process comprise: (i) removing heavy hydrocarbons from the second portion of the effluent stream and returning said hydrocarbons to the first portion of the effluent stream for recycle to the fluidised bed, (ii) removing substantially all of the monomers(s) from the second portion of the effluent stream and returning said monomers(s) to the first portion of the effluent stream for recycle to the fluidised bed, and (iii) recycling the second effluent stream after passage through the degassing vessel to the gaseous effluent stream.</p> |
