METHOD OF PRODUCTION OF LIQUID NITROGEN Russian patent published in 1997 - IPC

FIELD: cryogenic plants of nitrogen liquefaction. SUBSTANCE: gaseous nitrogen is divided into two parts after compression in compressors 2 and 3. One part of gas is subjected to liquefaction and other part of nitrogen at ambient temperature is directed to turboexpander 4 for production of cold which is used in heat exchanger 5 for removal of heat of gas being liquefied. Low-pressure nitrogen after compression in compressor 2 and cooling in heat exchanger 5 is fed to turbo-expander 6 in form of return flow vapors for generation of cold which is used in heat exchanger 7 for removal of heat from gas being liquefied at lower temperature level. After throttling, compressed and cooled nitrogen is drained to receiver 9 and vapor from receiver having passed the heat exchangers and completing the cycle flows for suction into compressor 2. EFFECT: enhanced efficiency. 3 cl, 1 dwg