METHOD AND APPARATUS FOR AIR SEPARATION BY CRYOGENIC DISTILLATION Russian patent published in 2011 - IPC F25J3/04 

FIELD: machine building.

SUBSTANCE: proposed method is implemented in distillation system comprising, at least, one high-pressure column (43) and low-pressure column (45). Air is compressed in main compressor (3), while compressed air is cooled in heat exchange line (41) and directed therefrom into high-pressure column (43). Under first operating condition, at least, 90% of compressed air is additionally compressed to first pressure exceeding that in high-pressure column (43) by 30 bars. Air at first pressure is directed into heat exchange line (41) to be cooled therein and separated into two parts, one intended for liquefying and sending into distillation system, while another part is subjected to expansion in turbo expander (29A, 29B) prior to directing into high-pressure column (43). Under second operating condition, no more than 70% of air compressed in main compressor (3) is additionally compressed to first pressure exceeding that in high-pressure column (43) by 30 bars. Air at first pressure is sent into heat exchange line (41) to be cooled therein and sent into distillation system, one intended for liquefying and sending into distillation system, while another part is subjected to expansion in turbo expander (29A, 29B) prior to directing into high-pressure column (43). At least, 30% of compressed air is sent into heat exchange line (41) at main compressor output pressure to be cooled therein and sent into high-pressure column (43).

EFFECT: reduced capital costs.

10 cl, 1 dwg