Patent ID: 9562716
Date: 2017-02-07
CPC Classifications: F25J

Claim:
1. A method for separating air by cryogenic distillation, the method comprising the steps of: i) sending N flows of air at approximately ambient pressure each to one of N air compressors; ii) compressing the air using each of the N compressors to a first pressure above 12 bar absolute and below 35 bar absolute, N being equal to or greater than 3 and the total power of the N compressors being greater than 10 MW; iii) sending the air at the first pressure from the N compressors to a single purification unit in order to remove water and carbon dioxide and cooling the air in the purification unit before sending the cooled air to a single system of columns in a single cold box where the cooled air is separated by cryogenic distillation; iv) extracting an enriched flow from the system of columns, wherein the enriched flow is selected from the group consisting of an oxygen-enriched flow, a nitrogen-enriched flow, and combinations thereof; v) sending the air from each of the N compressors to the system of columns through the purification unit, without sending the air at the first pressure to an air booster driven by a motor or a steam turbine; and vi) driving each of the N compressors by a single motor, these N motors being asynchronous and having a maximum power below 25 MW.