Separation vessels for use in polymerization processes and methods for cleaning same
First Claim
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.
1 Assignment
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Accused Products
Abstract
Both a system and method for cleaning a low pressure separation vessel of a high pressure polyethylene polymerization plant are provided. The system includes a polytetrafluoroethylene lining that covers the interior surfaces of the vessel, and a cover mounting assembly including an annular clamp for detachably mounting a cover over the vessel. The mounting assembly includes a clamp actuator for quickly securing and releasing the cover with respect to a top rim of the vessel. The vessel is drained of liquid polyethylene and allowed to cool to ambient temperature, thus creating a frozen “skin” of polyethylene around the interior surfaces of the vessel. The clamp actuator releases the cover. The polyethylene skin is peeled off the interior sides the vessel and gathered up at the top to form a neck, thus peeling the polyethylene skin away from the polytetrafluoroethylene lining along with any degraded polymers or other impurities that have accumulated on the interior surfaces of the vessel.
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Citations
10 Claims
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1. A method for removing polymer from a low pressure separation vessel in a high pressure polymerization plant comprising:
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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, and iii) 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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification