Method for cryogenic separation of air, and air separation plant

Abstract Method for cryogenic separation of air, and air separation plant A method for cryogenic separation of air using an air separation plant (100 - 900) is proposed, wherein, in a mass transfer column (13), a liquid first fluid and a gaseous 5 second fluid are subjected to mass transfer with one another, wherein a gaseous third fluid is removed from the mass transfer column (13) and is at least partly discharged from the air separation plant (100 - 900), wherein a liquid fourth fluid is removed from the mass transfer column (13) and is at least partly fed into a low-pressure column (12), and wherein the first fluid is formed using at least a part of an oxygen-rich liquid 10 removed from the low-pressure column (12). The second fluid is formed using an oxygen-enriched liquid removed from a high-pressure column (11). The oxygen enriched liquid removed from the high-pressure column (11) and bottom liquid of the mass transfer column (13) are mixed and, by means of a condenser-evaporator (7), partly evaporated, in which condenser-evaporator a liquid stream which comprises at 15 least a part of the oxygen-enriched liquid removed from the high-pressure column (11) and at least a part of the bottom liquid from the mass transfer column (13) is forced through an evaporation space by means of its own pressure and partly evaporated therein. A liquid fifth fluid is removed from the mass transfer column (13) between a feed point for the first fluid and a feed point for the oxygen-enriched liquid, and is at 20 least partly fed into the low-pressure column (12), wherein the fifth fluid or the fraction thereof fed into the low-pressure column (12) is fed into the low-pressure column (12) below the fourth fluid or the fraction thereof fed into the low-pressure column (12). The invention also relates to an air separation plant (100 - 900). 25 (Figure 1) 'I'l Em C)O -~CD t ®r * T * ~ /~~C4 Ca ce/