Low energy consumption method for separating gaseous mixtures and in particular for medium purity oxygen production

A method for the separation of gaseous mixtures, specifically air, for producing medium purity oxygen, comprising:

• compressing the gaseous mixture in a first compressor to about 3.9-4.1 atmospheres pressure, passing said compressed gaseous mixture in heat exchange relationship with sub-ambient temperature gaseous nitrogen, and dividing the cooled, pressurized gaseous mixture into first and second mixture streams;
• cooling the first mixture stream to its boiling point and introducing the cooled first mixture stream into the high pressure chamber of a double rectification column;
• compressing, cooling, condensing, and delivering the second mixture stream to the high pressure chamber of the double rectification column;
• separating the gaseous mixtures in the double rectification column into a liquid oxygen-enriched stream and a gaseous nitrogen stream, removing the gaseous nitrogen stream from the double rectification column for cooling said compressed gaseous mixture, removing the liquid oxygen-enriched stream from the low pressure chamber of the double rectification column, pumping the liquid oxygen-enriched product stream to a predetermined pressure, evaporating the oxygen-enriched product stream in an evaporator-condenser, heating the oxygen-enriched product stream, and blending the oxygen-enriched product stream with a compressed blend-air stream to the desired oxygen concentration.

A method for the separation of gaseous mixtures for producing medium purity higher boiling point component, comprising:

• compressing the gaseous mixture in a first compressor to super atmospheric pressure, and dividing the pressurized gaseous mixture into first and second mixture streams;
• cooling the first mixture stream to its boiling point and introducing the first mixture stream into the high pressure chamber of a double rectification column;
• compressing, cooling, and condensing the second mixture stream, and delivering the condensed second mixture stream to the high pressure chamber of the double rectification column;
• separating the gaseous mixtures in the double rectification column into a liquid higher boiling point component product stream and a gaseous lower boiling point component stream, removing said liquid higher boiling point component product stream from the low pressure chamber of the double rectification column, pumping said liquid higher boiling component product stream to a predetermined pressure, evaporating said pressurized liquid higher boiling point component product stream in an evaporator-condenser, heating said evaporated higher boiling point component product stream, and blending said heated higher boiling point component product stream with a compressed blend mixture stream to the desired higher boiling point component concentration.