Patent ID: 9733014
Date: 2017-08-15
CPC Classifications: F25J

Claim:
1. A method of obtaining compressed oxygen and compressed nitrogen by separation of air in a distillation-column system for nitrogen-oxygen separation, said distillation-column system having at least one high-pressure column ( 8 ) with bottom evaporator ( 9 , 209 ) and a low-pressure column ( 460 ), wherein the low-pressure column ( 460 ) is in heat-exchanging communication with the high-pressure column ( 8 ) via a main condenser ( 461 ), configured as a condenser-evaporator, said high-pressure column ( 8 ) having a top and a bottom, and said low-pressure column ( 460 ) having a top and a bottom, said method comprising: compressing feed air in an air compressor ( cooling the compressed feed air ( removing an oxygen-enriched liquid ( removing a nitrogen-enriched liquid ( removing an oxygen stream ( bringing a pressurized process stream ( withdrawing a gaseous circulation nitrogen stream ( withdrawing a first partial stream ( branching off a second partial stream of the gaseous circulation nitrogen stream upstream and/or downstream of said circulation compressor and/or of an intermediate stage of said circulation compressor at a product pressure (P, P wherein said circulation compressor ( wherein a third partial stream of the gaseous circulation nitrogen stream is withdrawn from said circulation compressor ( wherein in a first operating mode a fourth partial stream (