Process and apparatus for manufacturing ethylene polymers and copolymers
First Claim
1. A process for the manufacture of ethylene polymers and copolymers comprising the steps of:
- compressing ethylene in a primary compressor at a throughput of at least 55 tonnes/hour and then mixing that ethylene with recycled ethylene and further compressing the ethylene to a pressure of at least 2300 bar at a throughput of at least 120 tonnes/hour in a secondary compressor, heating at least a portion of the compressed ethylene to a temperature of at least 95°
C. and introducing that heated ethylene into the front end of a tubular reactor having a maximum internal diameter of at least 65 mm and a length of at least 1500 m, introducing initiator into the tubular reactor in at least three separate locations, thereby defining at least three reaction zones, allowing the ethylene to polymerize, and cooling the reaction mixture in at least the first two reaction zones, such that at least 28% of the monomer is converted to polymer, maintaining a pressure drop over the length of the tubular reactor such as to maintain a flow velocity in the tubular reactor of at least 6 m/s, releasing the reaction mixture through a high-pressure, let-down valve, cooling the reaction mixture and separating the reaction mixture in a product separator into polymer and unreacted ethylene, and recycling unreacted ethylene.
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Abstract
The invention relates to a process for the manufacture of ethylene polymers and copolymers in which ethylene is compressed in a primary compressor at a throughput of at least 55 tonnes/hour, mixed with recycled ethylene and further compressed in a two-stage reciprocating secondary compressor having at least 14 cylinders to a pressure of at least 2300 bar at a throughput of at least 120 tonnes/hour, heating at least a portion of that ethylene to a temperature of at least 95° C. and introducing it into a tubular reactor of diameter at least 65 mm and a length of at least 1500 m, introducing initiator in at least three reaction zones to give a conversion of at least 28% and maintaining a pressure drop over the reactor to maintain a flow velocity of at least 6 m/s.
37 Citations
18 Claims
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1. A process for the manufacture of ethylene polymers and copolymers comprising the steps of:
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compressing ethylene in a primary compressor at a throughput of at least 55 tonnes/hour and then mixing that ethylene with recycled ethylene and further compressing the ethylene to a pressure of at least 2300 bar at a throughput of at least 120 tonnes/hour in a secondary compressor, heating at least a portion of the compressed ethylene to a temperature of at least 95°
C. and introducing that heated ethylene into the front end of a tubular reactor having a maximum internal diameter of at least 65 mm and a length of at least 1500 m,introducing initiator into the tubular reactor in at least three separate locations, thereby defining at least three reaction zones, allowing the ethylene to polymerize, and cooling the reaction mixture in at least the first two reaction zones, such that at least 28% of the monomer is converted to polymer, maintaining a pressure drop over the length of the tubular reactor such as to maintain a flow velocity in the tubular reactor of at least 6 m/s, releasing the reaction mixture through a high-pressure, let-down valve, cooling the reaction mixture and separating the reaction mixture in a product separator into polymer and unreacted ethylene, and recycling unreacted ethylene. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. An apparatus for the manufacture of polyethylene and polyethylene copolymers comprising a primary compressor capable of a throughput of at least 55 tonnes/hr arranged to supply compressed ethylene to a two-stage secondary compressor and capable of compressing ethylene at a throughput of at least 120 tonnes/hr at a pressure of at least 2300 bar, the secondary compressor communicating, via a conduit provided with heating means to enable at least a portion of the compressed ethylene to be heated to at least 95°
- C., with the front end of a tubular reactor,
the secondary compressor optionally communicating via one or more further conduits with one or more points downstream of the front end of the tubular reactor for the supply of one or more ethylene sidestreams to the tubular reactor, the tubular reactor having at least three inlets for the injection of initiator thereby defining at least three reaction zones and being provided with a heating/cooling jacket in each reaction zone, the tubular reactor having a maximum internal diameter of at least 65 mm and being provided with a high-pressure, let-down valve, the production plant further comprising, a cooling means arranged downstream of the high-pressure, let-down valve, a product separator, and at least one conduit for the transfer of recycled ethylene from the product separator to the secondary compressor. - View Dependent Claims (17, 18)
- C., with the front end of a tubular reactor,
Specification