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Hydrocarbon gas processing

  • US 5,555,748 A
  • Filed: 06/07/1995
  • Issued: 09/17/1996
  • Est. Priority Date: 06/07/1995
  • Status: Expired due to Term
First Claim
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1. In a process for the separation of a gas stream containing methane, C2 components, C3 components and heavier hydrocarbon components into a volatile residue gas fraction containing a major portion of said methane and a relatively less volatile fraction containing at least a major portion of said C3 components and heavier hydrocarbon components, in which process(a) said gas stream is cooled under pressure to provide a cooled stream;

  • (b) said cooled stream is expanded to a lower pressure whereby it is further cooled; and

    (c) said further cooled stream is fractionated at said lower pressure whereby at least a major portion of said C3 components and heavier hydrocarbon components is recovered in said relatively less volatile fraction;

    the improvement wherein said gas stream is cooled sufficiently to partially condense it; and

    (1) said partially condensed gas stream is separated thereby to provide a first vapor stream and a first condensed stream;

    (2) said first vapor stream is thereafter divided into gaseous first and second streams;

    (3) said gaseous first stream is combined with at least a portion of said first condensed stream to form a combined stream;

    (4) said combined stream is cooled and expanded to an intermediate pressure whereby it is partially condensed;

    (5) said expanded partially condensed combined stream is separated at said intermediate pressure thereby to provide a second vapor stream and a second condensed stream;

    (6) said second vapor stream is further cooled at said intermediate pressure to condense substantially all of it, expanded to said lower pressure, and thereafter supplied at a top feed position to a distillation column in a lower region of a fractionation tower;

    (7) said second condensed stream is further cooled at said intermediate pressure, expanded to said lower pressure, and thereafter supplied to said distillation column at a first mid-column feed position;

    (8) said gaseous second stream is expanded to said lower pressure and thereafter supplied to said distillation column at a second mid-column feed position; and

    (9) the quantities and temperatures of said feed streams to the column are effective to maintain the tower overhead temperature at a temperature whereby at least a major portion of said C3 components and heavier hydrocarbon components is recovered in said relatively less volatile fraction.

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