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Method for producing a methane-rich stream and a C2+ hydrocarbon-rich stream, and associated equipment

  • US 10,619,919 B2
  • Filed: 12/26/2011
  • Issued: 04/14/2020
  • Est. Priority Date: 12/27/2010
  • Status: Active Grant
First Claim
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1. A method for producing a methane-rich stream and a C2+ hydrocarbon-rich stream from a feed stream containing hydrocarbons, said method comprising the following steps:

  • separating the feed stream into a first fraction of the feed stream and at least one second fraction of the feed stream;

    cooling the first fraction of the feed stream in a first heat exchanger to produce a cooled first fraction, said separating of the feed stream occurs upstream of the cooling of the first fraction of the feed stream;

    injecting the cooled first fraction of the feed stream in a first separating flask to produce a light head stream and a heavy bottoms stream;

    expanding a turbine feed fraction formed from the light head stream in a first dynamic expansion turbine to a first pressure and injecting at least part of the first expanded fraction coming from the first turbine into a first distillation column;

    expanding the whole heavy bottoms stream to form an expanded bottoms stream and injecting the expanded bottoms stream into the first distillation column without going through the first heat exchanger between the first separating flask and the first distillation column;

    recovering a bottoms stream at the bottom of the first distillation column, the C2+ hydrocarbon-rich stream being formed from the bottoms stream;

    recovering and heating a methane-rich overhead stream from the first distillation column;

    compressing at least one fraction of the methane-rich overhead stream in at least a first compressor coupled to the first dynamic expansion turbine and in at least one second compressor;

    injecting an entirety of the of the second fraction of the feed stream into a second dynamic expansion turbine, separate from the first dynamic expansion turbine, without cooling between the step for separating the feed stream and the step of injecting the second fraction of the feed stream into the second dynamic expansion turbine;

    expanding the entirety of the second fraction of the feed stream in the second dynamic expansion turbine to a second pressure, to form a second expanded fraction coming from the second dynamic expansion turbine, the second pressure being substantially equal to the first pressure; and

    cooling and at least partially liquefying at least part of the second expanded fraction coming from the second dynamic expansion turbine to form a cooled reflux stream, and injecting the cooled reflux stream into the first distillation column, wherein no stream issuing from the second dynamic expansion turbine enters into heat exchange in a heat exchanger with the first fraction of the feed stream, upstream of the distillation column.

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