Abstract: A method and apparatus for separating air to produce a gaseous oxygen product in which the air is separated in an air separation plant to conduct a cryogenic rectification process that utilizes higher and lower pressure compressed air streams. The higher and lower pressure compressed air streams are generated in two multistage compressors linked together so that the lower pressure compressed air stream is produced from intermediate stages and the higher pressure compressed air stream is produced from higher pressure compression stages. During turn-down operational conditions, one of the two multistage compressors can be shut down to decrease the flow of air and therefore, the production of the oxygen product.

Abstract: A cryogenic rectification system wherein low purity oxygen is recovered from a side column or the lower pressure column of a double column while a portion of the low purity oxygen is fed to an auxiliary column driven by fluid having a high nitrogen concentration wherein high purity oxygen is produced.

Abstract: A cryogenic air separation system wherein base load pressure energy is supplied to the feed air by a base load compressor and custom load pressure energy is supplied to the feed air by a bridge machine having one or more turbine booster compressors and one or more product boiler booster compressors, all of the compressors of the bridge machine driven by power supplied through a single gear case.

Abstract: A cryogenic rectification system for producing low purity oxygen and high purity oxygen employing an offset dual column with bottom reboil of the lower pressure column effected by condensing feed air, with intermediate reboil of the lower pressure column effected by condensing higher pressure column top vapor, and with waste nitrogen turboexpansion to generate refrigeration.