Process and device for producing nitrogen

Process and device for producing nitrogen

  • CN 1,141,547 C
  • Filed: 12/18/1996
  • Issued: 03/10/2004
  • Est. Priority Date: 12/18/1995
  • Status: Active Grant
First Claim
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1. method for preparing nitrogen, this method comprises:

  • Compressed purifying feeding air (10) is cooled to the temperature that is fit to rectifying;

    Described compressed purifying feeding air (10) is introduced destilling tower (12), produce highly purified rich nitrogen overhead product (14) and oxygen enriched liquid tower bottom product (28);

    Make at least a portion (16) condensation of the nitrogen-rich stream (14) that constitutes by above-mentioned rich nitrogen overhead product, and the part (22) of gained condensate liquid (20) is introduced into described destilling tower (12) as refluxing;

    Form nitrogen product stream from the remainder (23) of gained condensate liquid;

    Compress the circular flow (36) that one stream of oxygen-enriched liquid by partial gasification (34) forms, make this circular flow be cooled to described temperature, and be introduced into to described destilling tower to improve the rate of recovery of described nitrogen product;

    The cryogen flow expansion working that remainder (40) by the stream of oxygen-enriched liquid (34) of described gasification is formed, form main cryogen flow (44), and make this main cryogen flow (44) and described compressed purifying air (10) and described circular flow (36) carry out indirect heat exchange;

    The above-mentioned expansion work of some is used for described compression to circulating current (36);

    Make additional cryogen flow (48) gasification liquefaction again then from the nitrogen liquefaction unit;

    Described additional cryogen flow (48) is gasification at least in part by carrying out indirect heat exchange with at least a portion (16) of described nitrogen-rich stream (14), thereby helps to realize the condensation of described a part of nitrogen-rich stream (16);

    AndBefore described additional cryogen flow (48) liquefies again, make this additional cryogen flow (48) and described compressed purifying air (10) and circular flow (36) carry out indirect heat exchange, can be to increase in order to the quantity of the described expansion work of carrying out described compression, make it greater than not adding obtainable quantity when replenishing refrigeration, thereby further improve the rate of recovery of described nitrogen product.

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