Abstract: A process for the cryogenic distillation of air uses a distillation column system having a supplemental column and a distillation unit including a lower-pressure column and a higher-pressure column. A liquid stream enriched in oxygen is withdrawn from the lower-pressure column and is eventually vaporized through indirect latent heat transfer, thereby producing a reflux stream, a portion of which is eventually sent to the lower-pressure column, the higher-pressure column, and/or the supplemental column. At least a portion of the reflux for the supplemental column is eventually derived from the distillation unit. A nitrogen-enriched liquid removed from the distillation unit is increased in pressure and is fed to the supplemental column or back to the distillation unit. An oxygen-enriched fluid from the bottom of the supplemental column is fed to the distillation unit. At least some of the nitrogen product from the supplemental column is returned to the distillation unit.

Abstract: A method of producing a gaseous product, for instance gaseous oxygen in accordance with a cyclical demand pattern having high and low periods of demand. During periods of high demand, liquid is vaporized against condensing air which is in turn stored. During low demand periods, product is accumulated and previously stored liquid air is introduced into the column. During both high and low periods of demand liquid product is drawn to reduce the percentage variance in the required flow rate to the booster compressor used in producing the air to be liquefied. Preferably, during periods of high demand, a turbine used in generating refrigeration can be turned down to increase the amount of air available for condensation and with a reduction in production of liquid product.

Abstract: A first stream of air is compressed in a main air compressor and a booster compressor is cooled at a first pressure by passage through a main heat exchanger. The cooled stream is introduced without further compression into the higher pressure column of a double rectification column including in addition to the column a lower pressure column and a condenser-reboiler. A second stream of compressed air is expanded from a second pressure in an expansion turbine with the performance of external work. The expanded second stream of air is introduced into the lower pressure column. An oxygen product, typically impure, is taken from the bottom region of the lower pressure column. The second pressure is less than the first pressure column. The second pressure is less than the first pressure, the second air stream being taken from intermediate the compressors.

Abstract: A double column air separation method in which a first stream of compressed air is cooled by passage through a main heat exchanger from its warm end countercurrently to a nitrogen stream withdrawn from the top of a lower pressure rectification column. The first stream of compressed air flows from the main heat exchanger into a higher pressure rectification column through an inlet. A second stream of compressed air is also passed into the warm end of the main heat exchanger and is cooled therein. The second stream of compressed air passes out of heat exchange with the nitrogen stream at a temperature lower than the exit temperature therefrom of the first stream of compressed air and at least 5K lower than the bubble point temperature of air at the pressure prevailing at the inlet. A stream of oxygen-enriched liquid passes isenthalpically from the bottom of the higher pressure column to the lower pressure column.

Abstract: Nitrogen is produced by separation of it from air. Nitrogen so separated is condensed. Most or all of the nitrogen is separated by rectification. At least some of the condensed nitrogen is employed as reflux in the rectification. The nitrogen is both separated and condensed at three or more different pressures.

Abstract: A process for the production of oxygen and nitrogen is applicable when the oxygen product is withdrawn from a distillation column system as a liquid, pumped to an elevated pressure and warmed at least in part by cooling a suitably pressurized stream. At least a portion of the compressed, purified, and cooled air is introduced to a first of at least three distillation columns. The first distillation column contains at least a condenser at its top, produces at least an oxygen-lean stream from or near its top and a first oxygen-enriched liquid from its bottom. A second distillation column, which contains a reboiler in its bottom, has no condenser, receives at least a portion of nitrogen-enriched liquid as a feed to its top, and produces a first nitrogen-rich vapor stream from its top and a second oxygen-enriched liquid from its bottom.

Abstract: A method and apparatus of separating air to produce an oxygen product. In accordance with the method and apparatus the air is rectified within a double column arrangement. The lower pressure column has lower and intermediate reboilers. Nitrogen from the higher pressure column is compressed and sent to the lower reboiler and oxygen tower overhead from the higher pressure column is fed to the intermediate reboiler. The resultant liquid is used to reflux both columns. The advantages in the arrangement set forth above is that the higher pressure column may be made to operate at a lower pressure to conserve energy.

Abstract: Air is separated in a double rectification column including a lower pressure rectification column. A first oxygen product containing less than 3.5% by volume of argon impurity is withdrawn through an outlet of the column which has a packed section below the level of the outlet. The argon impurity is striped from liquid descending through the packed section and a second relatively pure oxygen product containing less than 100 volumes per million is withdrawn from below the section through an outlet thereof. Impurities less volatile than oxygen are preferably separated from the second oxygen product in a side rectification column.

Abstract: A double rectification column air separation method and apparatus in which a stream of oxygen-enriched liquid air from a higher pressure rectification column is at least partially vaporized in indirect heat exchange with a stream of purified, compressed, gaseous air. The stream of purified, compressed air is condensed and a stream of the resulting vapor after having been warmed is expanded in a turbine with the performance of external work. After expansion, the resulting vapor is introduced into the lower pressure rectification column and a stream of the resulting condensed air is introduced into the higher pressure column at an intermediate mass exchange level thereof.

Abstract: A method and apparatus for separating air to produce an oxygen product in which air is separated within a double column arrangement. In the double column arrangement part of the air to be separated reboils a lower pressure column and is then introduced into the higher pressure column for separation. Another part of the air is partially cooled and then expanded with the performance of work and then introduced into the lower pressure column to supply part of the refrigeration requirements. The remaining part of the refrigeration requirements is supplied by partially vaporizing a crude liquid oxygen stream within a head condenser used to produce reflux for the higher and lower pressure columns. The partially vaporized stream is then phase separated into liquid and vapor phases. The liquid phase is introduced into the lower pressure column and the vapor stream after having been partially warmed is turboexpanded to provide the remaining refrigeration requirements of the plant.

Abstract: Air is separated in a double rectification column including a lower pressure rectification column. A first oxygen product containing less than 3.5% by volume of argon impurity is withdrawn through an outlet of the column which has a packed section below the level of the outlet. The argon impurity is striped from liquid descending through the packed section and a second relatively pure oxygen product containing less than 100 volumes per million is withdrawn from below the section through an outlet thereof. Impurities less volatile than oxygen are preferably separated from the second oxygen product in a side rectification column.

Abstract: Air is separated in a double rectification column comprising a higher pressure rectification column, a lower pressure rectification column, and a condenser-reboiler placing the column in indirect heat exchange relationship with the column. A stream of pressurized liquid, comprising oxygen and nitrogen, typically taken from the bottom of the higher pressure rectification column, is expanded through a valve and is typically partially vaporized in a vaporizer-condenser which is separate from a second vaporizer-condenser in which argon is condensed. The vaporized liquid is expanded with the performance of external work in an expansion turbine and is introduced into the lower pressure rectification column. An oxygen product is withdrawn from the column through an outlet.

Abstract: Air is separated in a double rectification column comprising a higher pressure rectification column, a lower pressure rectification column and a condenser-reboiler placing the higher pressure rectification column in heat exchange relationship with the lower pressure rectification column. At least one stream of air is introduced into the double rectification column, a stream of pressurized liquid comprising oxygen and nitrogen is reduced in pressure by passage through a valve and is partially or totally vaporized in a vaporizer-condenser, a stream of resulting vapor from the partial or total vaporization is compressed in a compressor at cryogenic temperature and is introduced into the double rectification column, and an oxygen produce is withdrawn from the lower pressure rectification column through an outlet.

Abstract: Air is separated into oxygen and nitrogen in a double rectification column comprising a higher pressure rectification column and a lower pressure rectification column. Liquid nitrogen reflux for the separation is provided by condensing nitrogen vapor taken from the column in a condenser-reboiler. Additional separation is performed in an intermediate pressure rectification column. A first stream of argon-enriched vapor is withdrawn from an intermediate region of the lower pressure rectification column and has an argon fraction separated from it in a first side rectification column. A second stream of argon-enriched vapor is similarly withdrawn and is separated in a second side rectification column which provides vapor to heat a reboiler associated with the intermediate pressure rectification column. Alternatively a stream of oxygen vapor can be so employed instead of the second argon-enriched vapor stream.

Abstract: Air is separated in an arrangement of rectification columns including a double rectification column for separating oxygen and nitrogen from the air. The double rectification column comprises a higher pressure rectification column and a lower pressure rectification column. There is in addition a side rectification column for separating argon from a stream of argon-enriched oxygen/vapour withdrawn from the lower pressure rectification column. An intermediate pressure rectification column is employed to separate further nitrogen (oxygen-depleted vapour) from the air. An upward flow of vapour through the intermediate pressure rectification column is created by operation of a reboiler to boil liquid in the bottom of the column. In addition a flow of vaporised air is introduced into an intermediate mass transfer region of the column.

Abstract: Air is separated in an arrangement of rectification columns comprising a double rectification column having a higher pressure column and a lower pressure rectification column, an intermediate pressure rectification column, and a side rectification column communicating with the lower pressure column. The side rectification column is provided with a condenser and the intermediate pressure rectification column with a reboiler and a further condenser. A stream of oxygen-enriched liquid is withdrawn from the bottom of the higher pressure column through an outlet and is separated in the intermediate pressure rectification column. The reboiler is heated by a stream typically withdrawn from the side rectification column through an outlet thereof. The condensers of the side rectification column and the intermediate column are cooled by streams having different oxygen mole fractions.

Abstract: Air is separated in an arrangement of rectification columns comprising a double rectification column (which has a higher pressure column and a lower pressure column), an intermediate pressure rectification column and a side rectification column communicating with the lower pressure column. The side rectification column is provided with a condenser and the intermediate pressure rectification column with a reboiler and a condenser. A stream of oxygen-enriched liquid and a stream of liquid air are withdrawn from the higher pressure column through outlets and are separated in the intermediate pressure rectification column. The reboiler is heated by a stream typically withdrawn from the side rectification column through an outlet. A stream of liquid is withdrawn through an outlet at the bottom of the intermediate pressure rectification column is used to cool the condenser and is separated in the lower pressure rectification column.

Abstract: Air is separated in an arrangement of rectification columns comprising a double rectification column (which has a higher pressure column and a lower pressure column), an intermediate pressure rectification column, and a side rectification column communicating with the lower pressure column. The side rectification column is provided with a condenser, and the intermediate pressure rectification column with a reboiler and a further condenser. A stream of oxygen-enriched liquid is withdrawn from the bottom of the higher pressure column through an outlet and is separated in the intermediate pressure rectification column. The reboiler is heated by a stream typically withdrawn from the side rectification column through an outlet. A stream of liquid is withdrawn from the bottom of the intermediate pressure rectification column, is employed to cool the further condenser of the intermediate pressure rectification column, and is partially vaporised therein.

Abstract: A fractionation column has a first vapor inlet to a bottom mass exchange region of the column communicating with a source of vapor mixture to be separated and a second vapor inlet to an intermediate mass exchange region of the column. A valve means is operable to place the second inlet selectively in communication with the source of vapor mixture to be separated. The fractionation column may form part of an air separation apparatus.

Abstract: An inflatable life raft incorporates upper and lower canopies that are raised automatically above the upper or lower sides of the raft, respectively, depending on which side of the raft is facing upwardly when the raft is floating. The canopies each form a tent-like enclosure when raised to protect the raft occupants. The canopies are selectively raised by a generally vertically-oriented pillar slideably joined to the raft body, each end of the pillar being joined to corresponding upper and lower canopies. Preferably, the pillar is capable of floating to permit it to elevate above the raft body. The pillar may comprise an inflatable elongate member that slides disposed within an aperture within the floor. A skirt joins the pillar to the floor and provides a reversible waterproof seal between the pillar and the floor and limits the range of vertical travel of the pillar. One or more drain holes may be provided within the base of the skirt to allow the occupants to drain water from within the raft.