FIELD: machine engineering.
SUBSTANCE: cooled AIR (AIR) at a first separation pressure in a first separation column (S1) is separated into the head fraction enriched with nitrogen and the oxygen-enriched bottom fraction. Additional cooled AIR (AIR) in the mixing column (M) at the pressure of the mixing column is liquefied to obtain the bottom fraction of the mixing column by direct heat exchange with oxygen-enriched liquid flow. The oxygen- enriched flow is produced at least partially from the oxygen-enriched bottom fraction from the first separation column (S1). Additional cooled air (AIR) in the second separation column (S2) at the second separation pressure is also divided into the nitrogen-enriched head fraction and the oxygen-enriched bottom fraction. Nitrogen-enriched head fraction of second separating column (S2) is cooled at least partially by bottom fraction from mixing column (M). Nitrogen-enriched head fraction of second separating column (S2) is conducted at least partially through liquefaction chamber of dephlegmator (E2) of the second separating column (S2). The dephlegmator (E2) is made in form of condenser-evaporator whose evaporation chamber is operated at evaporator chamber pressure which is between the pressure of the mixing column and the third separating pressure. At the third separation pressure, a liquid oxygen-enriched flow is obtained in the third separation column (S3). The readily assembled dephlegmator (E2) in liquid form under pressure evaporator Chamber bring at least part of the lower fraction of mixing column (M), and as the first separation of pressure using the pressure at least 0.5 bar higher than the pressure, which is used as a second separating pressure. The air separation plant comprises a first separating column (S1), a mixing column (M), a second separating column (S2) and a third separating column (S3), executed with the possibility to perform the method.
EFFECT: increased air separation efficiency.
10 cl, 1 dwg
