| 摘要 |
In a method for air separation by cryogenic distillation in a three-column system, formed of a medium pressure column (9), an intermediate pressure column (25), and a low pressure column (19, 39) having at least a first and second vaporizer (52, 50), compressed air is sent, purified and cooled, into an exchange line (3) to the medium pressure column; flows enriched with nitrogen and oxygen derived from the medium pressure column are sent to the low pressure column; an oxygen-enriched liquid flow is sent from the medium pressure column to the intermediate pressure column; a first gas containing at least as much nitrogen as the air in the first vaporizer is sent into the low pressure column vat (52); a second gas containing at least as much nitrogen as the air in the second vaporizer (50) is sent to an intermediate level of the low pressure column; an oxygen-rich liquid is sent from the low pressure column vat to a head condenser (31, 59) of the intermediate pressure column or low pressure column; oxygen- and nitrogen-enriched liquids are sent from the intermediate pressure column to the low pressure column; an oxygen-rich gas is collected in the head condenser (31, 59) of the intermediate pressure column or low pressure column; and a nitrogen-rich gas is extracted from the head of the low pressure column. |
