METHOD FOR SEPARATING AIR BY CRYOGENIC DISTILLATION AND INSTALLATION THEREFOR

摘要

The invention concerns a method for separating air by cryogenic distillation using an apparatus comprising a medium pressure column (9) and a low pressure column (11) thermally communicating, which consists in cooling an amount of compressed and purified air V in an exchange line (10) to a cryogenic temperature and conveying at least part of it to the medium pressure column, conveying oxygen- and nitrogen-enriched flows (LR, LP) from the medium pressure column to the low pressure column and drawing nitrogen-and oxygen-enriched flows (35, 23) from the low pressure column. The invention is characterized in that the medium pressure column operates between 6 and 9 bar abs and the ratio between the total amount of air V entering the exchange line and the total volume of the exchange line ranges between 3000 and 6000 Nm3/h/m3.