Abstract: A method of producing gaseous oxygen in accordance with a variable demand cycle in which pumped liquid oxygen from a double column air separation unit is vaporized within a mixing column. During low demand phases, excess liquid oxygen is stored within a storage tank and used to augment the liquid oxygen to vaporized during the high demand phase. Reflux to the lower pressure column of the air separation unit is kept constant by storing liquid with column bottoms produced within the mixing column during the high demand phase for use in the low demand phase when less liquid oxygen is vaporized and therefore less column bottoms is produced in the mixing column.

Abstract: A method an apparatus for separating air in which an oxygen containing vapor stream is removed from a single column nitrogen generator and then divided into two subsidiary streams. The two subsidiary streams are condensed and then combined for stripping within a stripping column to produce ultra-high purity liquid oxygen as a column bottoms. One of the two subsidiary streams is condensed in a reboiler and a bottom region of the stripping column. The other of the two subsidiary streams is condensed within a head condenser used in connection with the nitrogen stripping column.

Abstract: A method and apparatus for generating nitrogen from the separation of air in a single column nitrogen generator. Nitrogen rich vapor is condensed to form reflux through the vaporization of an oxygen-rich liquid stream produced as column bottoms. The vaporized oxygen-rich stream is in part recompressed in a recycle compressor, cooled and reintroduced back into the column to increase nitrogen production. The vaporized oxygen-rich stream is also in part expanded with the performance of work. The work of expansion is applied to the compression. A supplemental refrigerant stream produced by a nitrogen liquefaction unit allows the nitrogen to be taken as a liquid and increases the amount of work of expansion able to be applied to the compression.

Abstract: A method of producing nitrogen is a single column nitrogen generator in which first and second coolant streams are used to condense nitrogen-rich tower overhead to provide reflux for the distillation column. One of the coolant streams is composed of liquid having a higher nitrogen content than oxygen-rich liquid produced in a bottom region of the distillation column. This coolant stream is compressed, cooled and recycled to the bottom of the distillation column in order to increase nitrogen recovery.

Abstract: A method and apparatus for producing a ultra-high purity oxygen product in which a nitrogen generator is operated to produce nitrogen and an oxygen rich fraction as column bottoms. Part of the oxygen rich fraction can be further processed at column pressure within rectification column to produce a tower overhead lean in hydrocarbons such as methane, acetylene, propane and propylene. After liquefaction in a head condenser of the rectification column, part of the condensate is further processed in a stripping column to produce an ultra-high purity liquid oxygen column bottoms which can be extracted as product.

Abstract: A process and apparatus for separating air in which a refrigerant stream produced at the top of a single column is expanded with the performance of work. Such expansion can be carried out in an expansion machine coupled to a recycle compressor by an energy dissipative brake. An oxygen stream is removed from a bottom region of the column and a compressor compresses an oxygen stream to column pressure which is at an above atmospheric delivery pressure. After compression, the oxygen stream is divided into two partial streams. One of the two partial streams is fed back into a bottom region of the column as a vapor to provide boil up while the other of the two partial streams is taken as a product which having been derrived from the compressed stream is therefore at the above-atmospheric delivery pressure. The refrigerant stream is heat exchanged countercurrently with incoming air to be separated in order to add refrigeration.