Single column process and apparatus for producing oxygen at above-atmospheric pressure

An apparatus for separating oxygen from air to produce an oxygen product, said apparatus comprising:

• means for compressing the air;
• means for purifying the air;
• a column for rectifying the air after having been cooled to a temperature suitable for its rectification to produce a nitrogen vapor tower overhead and a liquid oxygen column bottom within top and bottom regions of the column and a nitrogen rich fraction located below the nitrogen vapor tower overhead;
• condenser means for at least partial condensing a reflux stream composed of the nitrogen vapor tower overhead against vaporizing an oxygen stream composed of the liquid oxygen column bottom;
• reflux return means for returning at least part of the reflux stream back to the column as reflux;
• recycle compression means connected to the condenser means for compressing all of the oxygen stream to at least the superatmospheric pressure;
• dividing means connected to the compression means for dividing the oxygen stream into two partial stream;
• expansion means for expanding a refrigerant stream, composed of either the nitrogen vapor tower overhead or the nitrogen-rich vapor, with performance of work;
• the expansion means coupled to the recycle compression means so that all required compression work for compressing the oxygen stream is supplied from at least part of the work of the expansion;
• and
• heat exchange means for cooling the air to the temperature suitable for its rectification and for cooling one of the two partial streams to essentially, a dewpoint temperature against partially and then fully warming the refrigerant stream and fully the other of the two partial streams, the heat exchange means connected to the column such that the air is introduced into an intermediate point of the column and the other of the two partial streams is introduced into the bottom region of the column to provide boilup for said bottom region and the heat exchange means connected to the expansion means such that the refrigerant stream is introduced to the expansion means after having been partially warmed and is fully warmed after having been expanded.