Process for polymerizing olefin in gas phase
AssigneeBP Chemicals Limited
InventorJean-Claude Chinh
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Abstract
The present invention relates to a process for continuous gas-phase polymerization of olefin(s) in a fluidized and/or mechanically stirred bed reactor, comprising a stage of drawing off the polymer out of the reactor, wherein a portion of the bed is transferred into a lock hopper and is then isolated from the reactor in the lock hopper for a period of 5 to 120 seconds so that a substantial amount of the olefin(s) in the said portion polymerizes, before the polymer thus isolated in the said portion is discharged out of the lock hopper. The process advantageously reduces the amount of the gas drawn off with the polymer to be recycled into the reactor and improves the degassing of the polymer by the heat of the polymerization reaction during the isolation period in the lock hopper (FIG. 1).
Claims10
Process for continuous gas-phase polymerization of olefin(s) in a reactor containing a fluidized and/or mechanically stirred bed including a solid polymer, a catalyst and a reaction gas mixture containing the olefin(s) to be polymerized and passing through the reactor at a pressure higher than atmospheric pressure, a process characterized in that it comprises a stage of drawing off the polymer out of the reactor, in which stage a portion of the fluidized and/or mechanically stirred bed is transferred into a lock hopper by bringing the reactor into communication with the lock hopper, and is then isolated in the lock hopper for a period of 5 to 120 seconds, so that a substantial quantity of the olefin(s) present in the said transferred portion polymerizes, before the polymer thus isolated in the said transferred portion is discharged out of the lock hopper.
Dependencies are inferred from the claim text.