METHOD OF POLYMERIZING OLEFINS IN SLURRY REACTORS

摘要

A process including polymerizing ethylene in the presence of a polymerization catalyst and hydrogen in a first polymerization reactor to produce a first slurry; withdrawing a first stream of the slurry from the first polymerization reactor; directing the slurry stream into a second polymerization reactor; polymerizing ethylene in the presence of the first ethylene polymer, the polymerization catalyst, and hydrogen in a second polymerization reactor to produce a second slurry; withdrawing from the second polymerization reactor a second slurry stream having a solids concentration higher than the average solids concentration of the second slurry within the second polymerization reactor; withdrawing from the second polymerization reactor a third slurry stream having a solids concentration lower than the average solids concentration of the second slurry within the second polymerization reactor; and directing at least a part of the second slurry stream into one of the first and second polymerization reactors.

主权项

1. A process for producing ethylene polymers in at least two cascaded polymerization reactors comprising the steps of:
polymerizing ethylene in the presence of a polymerization catalyst, hydrogen and optionally one or more alpha-olefin comonomers in a diluent in a first polymerization reactor to produce a first slurry comprising a first ethylene polymer and fluid phase comprising said diluent; withdrawing a first stream of said slurry from said first polymerization reactor; directing said slurry stream into a second polymerization reactor; polymerizing ethylene in the presence of the first ethylene polymer, the polymerization catalyst, hydrogen and optionally one or more alpha-olefin comonomers in a diluent in a second polymerization reactor to produce a second slurry comprising an ethylene polymer mixture and a fluid phase comprising said diluent; withdrawing from said second polymerization reactor a second slurry stream having a solids concentration which is higher than the average solids concentration of the second slurry within the second polymerization reactor; withdrawing from said second polymerization reactor a third slurry stream having a solids concentration which is lower than the average solids concentration of the second slurry within the second polymerization reactor;characterized in that the process further comprises the following step:
directing at least a part of said second slurry stream into one of said first and second polymerization reactor.