Oxygen and nitrogen extracted by low-temperature fractional distillation

摘要

Extracting a pressurized product (24, 25; 550, 551) by low-temperature fractional distillation of air involves the use of a rectification system which has a pressure column (4) and a low-pressure column (9). Compressed and filtered air (1, 3) is admitted to the pressure column (4). One fraction (6) of gas in the pressure column (4) is allowed to expand (8) into the low pressure column (9). An oxygen-rich fraction (17; 445) from the low-pressure column (9) is pressurized in liquid form (18; 446) and introduced (26) into the mixer column (27) (contra-flow contact column). A heat conductor (1, 38,39, 40; 1, 238, 239,40; 1, 338, 339, 40) is introduced into lower zone within the mixer column (27) and brought in counter-flow contact with the oxygen-rich fraction (26). A gaseous product (28) is removed from the upper part of the mixer column (27). One product fraction (17; 417; 547) is removed from the rectification system and pressurized into liquid form (18; 418; 548), evaporated in a condenser- evaporator (22, 549), and tapped off as a pressurized product (24, 25; 550, 551). The gaseous product (28) from the head of the mixer column (27) is introduced into the condenser-evaporator (22; 549) liquefaction chamber, where it condenses in indirect heat-exchange against the evaporating product fraction. An Independent claim is also included, describing a device for carrying out the process.