×

Low pressure chilling train for olefin plants

  • US 5,647,972 A
  • Filed: 01/05/1995
  • Issued: 07/15/1997
  • Est. Priority Date: 01/05/1995
  • Status: Expired due to Term
First Claim
Patent Images

1. A method of processing, at a relatively low pressure, a cracked gas feedstream containing hydrogen, methane, C3 to C5 hydrocarbons and C6 and heavier hydrocarbons to separate hydrogen and methane and produce a hydrogen stream at a relatively high pressure comprising:

  • a. compressing said feedstream to a pressure of less than 27 bars;

    b. cooling said compressed feedstream to a temperature in the range of 10°

    to 25°

    C. thereby forming a first condensed portion and a first vapor portion of said compressed feedstream and separating said first condensed portion and said first vapor portion;

    c. drying said first condensed portion and said first vapor portion;

    d. cooling said dried first vapor portion to a temperature in the range of -20°

    to 5°

    C. thereby forming a second condensed portion and a second vapor portion;

    e. feeding said first and second condensed portions to a stripper tower wherein said condensed portions are separated into a stripper bottoms containing essentially all of said C6 and heavier hydrocarbons and a stripper overhead containing at least a portion of said C3 to C5 hydrocarbons;

    f. combining said second vapor portion and said stripper overhead to produce a combined vapor stream containing hydrogen, methane and C3 to C5 hydrocarbons with essentially no C6 and heavier hydrocarbons;

    g. cooling said combined vapor stream to a temperature range of -110°

    to -72°

    C. thereby forming a third condensed portion and a third vapor portion;

    h. dividing said third condensed portion into at least two demethanizer feed portions;

    i. feeding a first one of said demethanizer feed portions directly to a demethanizer at a selected feed location;

    j. heating a second one of said demethanizer feed portions to a temperature higher than said first one of said demethanizer feed portions and feeding into said demethanizer at a feed location below said selected feed location;

    k. cooling said third vapor portion to a temperature range of -145°

    to -120°

    C. thereby forming a fourth condensed portion and a fourth vapor portion containing essentially only hydrogen, methane and a quantity of C2 hydrocarbons;

    l. feeding said fourth condensed portion to said demethanizer at a feed location above said selected feed location;

    m. separating in said demethanizer an overhead containing essentially only hydrogen, methane and a quantity of C2 hydrocarbons and a bottoms containing C2 and heavier hydrocarbons;

    n. compressing and thereby heating said demethanizer overhead and said fourth vapor portion to a pressure of 25 to 45 bars; and

    o. cooling said compressed demethanizer overhead and fourth vapor portion to a temperature in the range of -140°

    to -100°

    C. thereby forming a condensed demethanizer reflux and a vapor containing essentially only hydrogen and methane.

View all claims
  • 2 Assignments
Timeline View
Assignment View
    ×
    ×