FIELD: machine building.
SUBSTANCE: air separation unit includes main air compressor, main heat exchanger (8) and system of distillation columns with high and low pressure columns. Supply air (1) is compressed in main air compressor (3). First air flow (100) is cooled in main heat exchanger (8) and liquefied, then expanded (101) and introduced (102, 9) into system of distillation columns. Second air flow (200) is compressed in additional compressor (202c). First partial flow of the second air flow (210) is introduced into first turbine (202t) and then introduced (211, 213, 22) into the system of distillation columns. From time to time liquid product (30; 39; LAR) is extracted in system of distillation columns and is withdrawn from air separation plant. First product stream (37; 43) in liquid form is removed from the system of distillation columns, compressed, in the main heat exchanger (8) evaporated and heated and then extracted as the first compressed gaseous product. From time to time the second partial flow of the second air flow (230) in cold compressor (14c) is compressed, cooled and liquefied in the main heat exchanger (8), then expanded (233) and introduced (234, 9) into the system of distillation columns. Air flow (230) has one of the following properties: its number in the second operating mode is higher than in the first operating mode, its pressure at the outlet of the cold compressor in the second operating mode is higher than in the first operating mode.
EFFECT: invention relates to low-temperature air separation.
10 cl, 1 dwg
