Cascade connection method for preparing liquefied natural gas

Cascade connection method for preparing liquefied natural gas

  • CN 101,126,041 A
  • Filed: 08/23/2007
  • Published: 02/20/2008
  • Est. Priority Date: 03/28/2007
  • Status: Active Grant
First Claim
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1. a compact cascade type prepares the method for natural gas liquids, has following steps:

  • 1. pre-treatment;

    Remove carbonic acid gas, hydrogen sulfide and water in the unstripped gas;

    2. the one-level cooling is handled;

    Make pretreated unstripped gas through first multi-stage heat exchanger in first cooling cycle system (1) and tripping device (2), handle pretreated unstripped gas is carried out the one-level cooling, make unstripped gas be cooled to subzero 35~

    subzero 41 ℃

    , air pressure is 3.8MPa to 4.1MPa;

    3. the secondary cooling is handled;

    Make the unstripped gas that passes through after 2. step is handled successively through second multi-stage heat exchanger in second cooling cycle system (3) and tripping device (4), so that being carried out the secondary cooling, handles the unstripped gas after 2. handling through step, make unstripped gas be cooled to subzero 95~

    subzero 100 ℃

    , air pressure is 3.8MPa to 4.1MPa;

    4. three grades of coolings are handled;

    Make the unstripped gas that passes through after 3. step is handled successively through the 3rd multi-stage heat exchanger in the 3rd cooling cycle system (5) and tripping device (6), handle the unstripped gas of 3. handling through step is carried out three grades of coolings, make unstripped gas be cooled to subzero 155~

    subzero 161 ℃

    , air pressure is 3.8MPa to 4.1MPa;

    5. the throttling step-down is handled;

    the unstripped gas after 4. the process step is handled is expanded, make unstripped gas be cooled to subzero 162 ℃



    163 ℃ and

    become the mixture that contains natural gas liquids and gaseous natural gas, make material through gas-liquid separation tower (8) then, make liquify natural gas separate, thereby obtain the finished product natural gas liquids with gaseous natural gas.

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