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Separation vessels for use in polymerization processes and methods for cleaning same

  • US 10,358,511 B2
  • Filed: 01/13/2017
  • Issued: 07/23/2019
  • Est. Priority Date: 12/22/2009
  • Status: Active Grant
First Claim
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1. A method for removing polymer from a low pressure separation vessel in a high pressure polymerization plant comprising:

  • providing a low pressure separation vessel which had been in operation as part of a high pressure polymerization process, said vessel comprising;

    i) a detachable cover,ii) a low-stick lining that covers at least a portion of the interior surfaces of the vessel, said low-stick lining producing a reduced tendency for polymer product to adhere to a surface so lined as compared to a surface without such low-stick lining, andiii) a liquid polymer, comprising at least one of polyethylene or polypropylene, which is the reaction product of the high pressure polymerization process;

    removing the detachable cover from the low pressure separation vessel;

    emptying the low pressure separation vessel of the liquid polymer;

    cooling the low pressure separation vessel an amount sufficient to freeze the liquid polymer clinging to the interior surfaces of the low pressure separation vessel to form a skin layer of the liquid polymer, wherein the skin layer is disposed on the low-stick lining; and

    removing the skin layer from the low pressure separation vessel.

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