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Hydrocarbon gas processing

  • US 5,568,737 A
  • Filed: 11/10/1994
  • Issued: 10/29/1996
  • Est. Priority Date: 11/10/1994
  • 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 a major portion of said C2 components, C3 components and heavier 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 the major portion of said C2 components, C3 components and heavier 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 vapor stream and a condensed stream;

    (2) said 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 condensed stream to form a combined stream and said combined stream is cooled to condense substantially all of it and is thereafter expanded to said lower pressure whereby it is further cooled;

    (4) said expanded cooled combined stream is thereafter supplied at a first mid-column feed position to a distillation column in a lower region of a fractionation tower;

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

    (6) a distillation stream is withdrawn from an upper region of said tower and is warmed;

    (7) said warmed distillation stream is compressed to higher pressure and thereafter divided into said volatile residue gas fraction and a compressed recycle stream;

    (8) said compressed recycle stream is cooled sufficiently to substantially condense it;

    (9) said substantially condensed compressed recycle stream is expanded to said lower pressure and supplied to said fractionation tower at a top feed position; and

    (10) the quantity and pressure of said compressed recycle stream and the quantities and temperatures of said feed streams to the column are effective to maintain tower overhead temperature at a temperature whereby the major portion of said C2 components, C3 components and heavier hydrocarbon components is recovered in said relatively less volatile fraction.

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