Abstract: The process and device are used to obtain a compressed product by low temperature separation of air in a rectification system which has a pressure column and a low pressure column. A first flow of compressed and purified feedstock air is cooled in a main heat exchanger system and is fed into the pressure column. At least one fraction from the pressure column is expanded and fed into the low pressure column. An oxygen-rich fraction from the low pressure column is liquid-pressurized and delivered to a mixing column. A heat exchange medium is fed into the lower area of the mixing column and is brought into countercurrent contact with the oxygen-rich fraction. A gaseous top product is removed from the upper area of the mixing column. A product fraction is removed from the rectification system, liquid-pressurized, vaporized in indirect heat exchange with the gaseous top product of the mixing column and is withdrawn as the compressed product.

Abstract: Oxygen-containing gas comprising no more than about 50 mol % oxygen is fed (150) to an auxiliary separation column (40) in a multiple column cryogenic air distillation system comprising at least a higher pressure (“HP”) column (10) and a lower pressure (“LP”) column (30) for separation into nitrogen-rich overhead vapor and oxygen-rich liquid. Oxygen-rich liquid is fed (154) from the auxiliary column (40) to an intermediate location in the LP column (30). The auxiliary column (40) is refluxed with a liquid stream from or derived from the HP column (10). One advantage of the invention is that the diameter of the upper sections (II, III) of the LP column (30) need no longer be larger than the diameter of the rest of the column system thereby increasing the capacity of the column system (under the constraint of a defined maximum column section diameter).

Abstract: A cryogenic rectification system for producing low purity oxygen from an auxiliary column to a double column system and which can also effectively produce nitrogen gas product and/or one or more liquid products wherein the lower pressure column of the double column system is reboiled in part by turboexpanded shelf vapor which is condensed in an intermediate reboiler and preferably subcooled prior to passage into the lower pressure column.

Abstract: A method for cryogenic air separation wherein at least a portion of the feed air to the cryogenic air separation plant is partially condensed and the resulting two-phase feed air stream is turboexpanded to produce refrigeration and a resulting two-phase feed air stream, which has a liquid portion less than that of the input two-phase feed air stream to the turboexpander, prior to being passed into the cryogenic air separation plant.

Abstract: The process and the apparatus serve for separating a gas mixture in a separation plant. A feed gas (18) is introduced into a compressor system (6, 16) and then into the separation plant. In the event of loss or partial loss of the compressor system (6, 16) of the first feed gas compressor (6), a first auxiliary stream (91, 92) which has approximately the composition of the first product stream or approximately the composition of the feed gas is compressed (78, 89) to at least approximately the first pressure and is recirculated to the separation plant.

Abstract: Oxygen-containing gas comprising no more than about 50 mol % oxygen is fed (150) to an auxiliary separation column (40) in a multiple column cryogenic air distillation system comprising at least a higher pressure (“HP”) column (10) and a lower pressure (“LP”) column (30) for separation into nitrogen-rich overhead vapor and oxygen-rich liquid. Oxygen-rich liquid is fed (154) from the auxiliary column (40) to an intermediate location in the LP column (30). The auxiliary column (40) is refluxed with a liquid stream from or derived from the HP column (10). One advantage of the invention is that the diameter of the upper sections (II, III) of the LP column (30) need no longer be larger than the diameter of the rest of the column system thereby increasing the capacity of the column system (under the constraint of a defined maximum column section diameter).

Abstract: A method to obtain a gaseous product by the low temperature fractionation of air includes supplying a first, purified and cooled stream of air to a high-pressure column. At least one liquid stream from the high-pressure column is passed into a low-pressure column. A product stream in the liquid state is drawn off from the low-pressure column and is brought to an elevated pressure. The product stream is then evaporated in an indirect heat exchange with a second purified stream of air. The second stream of air, which is condensed at least partly during the indirect heat exchange, is expanded at least partly in a work-producing manner. The second stream of air subsequently is passed into the low-pressure column. The pressure of the second stream of air at the outlet of the work-expansion is lower than the operating pressure in the sump of the high-pressure column. The work-expansion of the second stream of air is carried out in a single step.

Abstract: The process and the apparatus are used to obtain argon using a three-column system for the fractionation of air, which has a high-pressure column (11), a low-pressure column (13) and a medium-pressure column (12). A first charge air stream (10, 64) is introduced into the high-pressure column (11), where it is separated into a first oxygen-enriched liquid and a first nitrogen top gas. A first oxygen-enriched fraction (23, 24, 26) from the high-pressure column (11) is introduced into the medium-pressure column (12), where it is separated into a second oxygen-enriched liquid and a second nitrogen top gas. A second oxygen-enriched fraction (33, 35), from the high-pressure column and/or from the medium-pressure column (12), is introduced into the low-pressure column (13), where it is separated into a third oxygen-enriched liquid and a third nitrogen top gas.

Abstract: A method for providing refrigeration to a cryogenic rectification plant which enables the facile provision of varying amounts of refrigeration to the plant wherein a working fluid is pressurized in a recycle compressor, a first portion is at least partially condensed in a heat exchanger and passed into the plant, a second portion is cooled and then turboexpanded to generate refrigeration, the refrigeration bearing second portion passes refrigeration in the heat exchanger to the first portion to effect the condensation, and the resulting second portion is not passed into the cryogenic rectification plant but rather is returned to the recycle compressor.

Abstract: A three column cryogenic rectification system for producing at least one of oxygen and nitrogen employing a medium pressure column which is operating at a pressure between the operating pressures of the higher and lower pressure columns, and which receives an air feed which is at a lower pressure than the air feed to the higher pressure column. The medium pressure column processes oxygen-enriched liquid from the higher pressure column and is reboiled by a fluid taken from below the top of the higher pressure column.

Abstract: In a plant for separating air which does not comprise an argon column, an intermediate-pressure column (102) has a bottom reboiler (24) which is heated by a gas (233) coming from the low-pressure column (103). The intermediate-pressure column is fed from the high-pressure column (101). This makes it possible to reduce the energy consumption while improving the efficiency of the process.

Abstract: The process and device are used to obtain a compressed product by low temperature separation of air in a rectification system which has a pressure column and a low pressure column. A first flow of compressed and purified feedstock air is cooled in a main heat exchanger system and is fed into the pressure column. At least one fraction from the pressure column is expanded and fed into the low pressure column. An oxygen-rich fraction from the low pressure column is liquid-pressurized and delivered to a mixing column. A heat exchange medium is fed into the lower area of the mixing column and is brought into countercurrent contact with the oxygen-rich fraction. A gaseous top product is removed from the upper area of the mixing column. A product fraction is removed from the rectification system, liquid-pressurized, vaporized in indirect heat exchange with the gaseous top product of the mixing column and is withdrawn as the compressed product.

Abstract: A cryogenic air separation process for the production of oxygen and nitrogen products uses a distillation system having at least a higher pressure column and a lower pressure column. A nitrogen-enriched liquid stream is recovered from the higher pressure column and is eventually at least partially vaporized by indirect heat exchange at a pressure intermediate that of the higher pressure column and the lower pressure column. A vapor stream is withdrawn from an intermediate location of the stripping section of the lower pressure column and is at least partially condensed by indirect heat exchange with the nitrogen-enriched liquid stream. At least some of the nitrogen product is recovered from the vapor that results from the at least partial vaporization of the nitrogen-enriched liquid. The process is appropriate for the production of nitrogen in quantities up to 40 mole % of the incoming air flow.

Abstract: The process and the apparatus are used to obtain argon using a three-column system for the fractionation of air, which has a high-pressure column (11), a low-pressure column (13) and a medium-pressure column (12). A first charge air stream (10, 64) is introduced into the high-pressure column (11), where it is separated into a first oxygen-enriched liquid and a first nitrogen top gas. A first oxygen-enriched fraction (23, 24, 26) from the high-pressure column (11) is introduced into the medium-pressure column (12), where it is separated into a second oxygen-enriched liquid and a second nitrogen top gas. A second oxygen-enriched fraction (33, 35), from the high-pressure column and/or from the medium-pressure column (12), is introduced into the low-pressure column (13), where it is separated into a third oxygen-enriched liquid and a third nitrogen top gas.

Abstract: An air separation plant producing pressurized gaseous oxygen includes at least one column having a bottom reboiler. The column is fed with a stream of air. The bottom reboiler is warmed by a nitrogen-enriched gas compressed in a cold compressor and pumped liquid oxygen is withdrawn from the bottom of the column, pumped and vaporized. The refrigeration for the process is produced by air expansion in a turbine.

Abstract: A process of liquefying gas to produce a liquid cryogen comprising compressing a gas stream using a compressor, work expanding the compressed gas stream using at least one expansion turbine to produce an expanded gas stream together with power, mechanically transferring the power generated by the expansion turbine(s) to drive the compressor, using the expanded gas stream to provide refrigeration duty for liquefaction, and recycling the cooled expanded compressed gas stream to the compressor.

Abstract: An air separation plant producing pressurized gaseous oxygen comprises at least one column (17) having a bottom reboiler (19) and fed with a stream of air. The bottom reboiler is warmed by a nitrogen-enriched gas (25) compressed in a cold compressor (21) and pumped liquid oxygen (33) is withdrawn from the bottom of the column, pumped and vaporized. The refrigeration for the process is produced by air expansion in a turbine (15).

Abstract: The process and the apparatus serve for the low-temperature fractionation of air. Compressed and prepurified feed air (3, 5) is introduced into a rectification system for nitrogen-oxygen separation which has a pressure column (6). At least a part of the compressed and prepurified feed air is fed (5) to the pressure column (6). An oxygen-enriched fraction (13) is taken off from the pressure column (6) and passed (14) to a further working step (7) within the rectification system. The oxygen-enriched fraction (13) is taken off at least one theoretical or actual plate (15) above the point at which the compressed and prepurified feed air (5) is fed to the pressure column. From the bottom of the pressure column (6) a purge fraction (16) is removed in the. liquid state, fed in the liquid state to a purification stage (17), in which N2O is removed, and is taken off from the purification stage (17) as purified purge fraction (18).

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 to obtain a gaseous product by the low temperature fractionation of air includes supplying a first, purified and cooled stream of air to a high-pressure column. At least one liquid stream from the high-pressure column is passed into a low-pressure column. A product stream in the liquid state is drawn off from the low-pressure column and is brought to an elevated pressure. The product stream is then evaporated in an indirect heat exchange with a second purified stream of air. The second stream of air, which is condensed at least partly during the indirect heat exchange, is expanded at least partly in a work-producing manner. The second stream of air subsequently is passed into the low-pressure column. The pressure of the second stream of air at the outlet of the work-expansion is lower than the operating pressure in the sump of the high-pressure column. The work-expansion of the second stream of air is carried out in a single step.

Abstract: Air is separated in a triple column comprising a high pressure column, an intermediate pressure column and a low pressure column, the intermediate pressure column being fed by oxygen enriched liquid from the high pressure column. The low pressure column feeds an argon column with argon enriched liquid and operates at a higher pressure than the argon column. Heat is supplied to the bottom of the argon column by sending gas to a bottom reboiler. This gas is preferably rich in nitrogen and may come from the top of the low pressure column.

Abstract: Air is distilled in a single column installed on a boat, and from here an oxygen-enriched liquid flow is drawn off. This flow is pressurized by a pump and vaporized by heat exchange with air or nitrogen. The oxygen is used for the partial oxidation of a flow contained hydrocarbons, for example natural gas.

Abstract: The method and the device are used for the cryogenic separation of air. Compressed and purified application air (9, 10, 20) is cooled in a main heat exchanger (30) and is at least partially fed (12, 33) to a rectifying column (50). A first partial flow (26) of the application air is fed to the main heat exchanger (30), is at least partially withdrawn at a first intermediate temperature from the main heat exchanger (28), and is fed to a cold compression (29). The first partial flow (26) is warmed up (27) upstream of its withdrawal (28) at the first intermediate temperature in the main heat exchanger (30).

Abstract: An method for the recovery of oxygen at hyperbaric pressure by low-temperature air fractionation includes compressing feed air to a first pressure, which is about the same as the operating pressure of the pressure column. At least a first partial flow of the feed air is cooled in a main heat exchanger and passed into the pressure column. An oxygen flow is tapped from the low-pressure column; brought to a delivery pressure that is higher than the operating pressure of the low-pressure column; heated in the main heat exchanger; and discharged as product. The pressure of a process stream from the main heat exchanger is relieved in a work-expanding manner, and the process stream is supplied to the low-pressure column. At least a portion of the mechanical energy generated by the work-expanding is used to drive a cold compressor.

Abstract: For producing a pressurized product by low-temperature producing a pressurized product by low-temperature fractionation of air in a rectification system which has a high-pressure column (13) and a low-pressure column (14), a first feed airstream (12) is introduced into the high-pressure column (13), and an oxygen-rich fraction (38) from the low-pressure column (14) is brought (39) to pressure in the liquid state and introduced (41) into a mixing column (16). A second feed airstream (6, 15) is introduced into the lower region of the mixing column (16) and brought into countercurrent contact with the oxygen-rich fraction (41). The mixing column (16) is operated at a pressure (PM1S) which is lower than the operating pressure (pHDS) of the high-pressure column (13).

Abstract: In a process for production of oxygen enriched fluid and argon enriched fluid by cryogenic distillation of air, a feed stream (1) containing nitrogen, oxygen and argon is sent to a main column system wherein it is separated by cryogenic distillation, an argon containing gaseous stream (33) is removed from a column (103) of the main column system, said column operating at a pressure of at least 2 bar abs., and the argon containing gaseous stream is at least partially condensed, at least part of the at least partially condensed argon containing gaseous stream is sent to an intermediate point of an argon column (104) and an argon enriched product stream (80) is removed from the top of the argon column and a first oxygen enriched product stream (36) is removed from the bottom of the argon columnn.

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: A cryogenic air separation system for producing oxygen employing a double column and a side column wherein side column liquid is vaporized against nitrogen heat pump fluid taken from the higher pressure column of the double column and then used to reflux the higher pressure and/or lower pressure columns of the double column.

Abstract: In an integrated power generation system, part of the air from a gas turbine compressor is separated in a single nitrogen wash column to remove oxygen and the gaseous nitrogen produced at the top of the column is sent back to a point upstream of the expander of the gas turbine. The wash column may be fed with liquid nitrogen from an independent air separation unit in which air is separated. Liquid from the bottom of the wash column may be fed back to the air separation unit. In order to boost production of an air separation plant, an additional plant is linked with the original plant. For example, air may be separated in a single nitrogen wash column to remove oxygen and gaseous nitrogen is produced at the top of the column. The wash column is fed with liquid nitrogen from the high pressure column of the air separation unit. Liquid from the bottom of the wash column may be fed back to the air separation unit.

Abstract: Air is separated in a triple column system comprising a high pressure column, an intermediate pressure column and a low pressure column. An argon enriched liquid from the low pressure column feeds an argon column. Oxygen enriched fluids containing at least 95% oxygen are removed from the argon column and optionally from the low pressure column.

Abstract: A process purifies and recovers a major component from a feed stream containing: the major component at a concentration of at least 90 mole %, at least one light component having a greater volatility than the volatility of the major component, and at least one heavy component having a lesser volatility than the volatility of the major component. The process uses a distillation system, wherein at least three streams are produced: the purified major component, a stream enriched in a light component, and a stream enriched in a heavy component. The distillation system includes a higher pressure column and a lower pressure column with thermal linking achieved by condensing at least some of the vapor from the higher pressure column in a reboiler-condenser which provides at least some of the boilup for the lower pressure column. The process is applicable to the purification and recovery of electronic-grade oxygen from a standard-grade oxygen supply.

Abstract: An efficient multieffect distillation process separates multicomponent mixtures containing three or more components into product streams each enriched in one of the components. The distillation process consists of at least two distillation columns that are thermally linked. A mixture stream that can be the given feed or a stream recovered from another distillation column and containing three or more components is fed to one of the thermally linked distillation columns and at least two submixture streams are produced from this distillation column and transferred to other distillation columns for further distillation. At least one of the submixture streams is transferred to the other thermally linked distillation column. One submixture stream is lean in the least volatile component of the mixture feed and the other submixture stream is lean in the most volatile component of the mixture feed.

Abstract: A cryogenic air separation process for producing liquid oxygen and other liquid products wherein refrigeration generation for the process is decoupled from the flow of process streams and is produced at least in part by at least on multicomponent refrigerant fluid refrigeration circuit.

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: In an apparatus for the separation of air by cryogenic distillation, all of the air is compressed to a medium pressure. Next, one part of the air is compressed to an intermediate pressure and a fraction of this air is compressed to a high pressure. The high-pressure air is divided into at least two fractions and expanded in two turboexpanders, the cooled stream from the warm turboexpander being at least partially recycled into the warm end of the exchanger at a higher pressure. A liquid coming from the air separation apparatus vaporizes in the exchanger.

Abstract: A cryogenic air separation process having improved flexibility and operating efficiency for producing elevated pressure gaseous oxygen by vaporizing pressurized liquid oxygen wherein refrigeration generation for the process is decoupled from the flow of process streams and is produced by one or more multicomponent refrigerant fluid circuits.

Abstract: A process is provided for the production of intermediate pressure oxygen. Intermediate pressure is defined as a pressure range between about 15 psia and about 27 psia, and preferably between about 17 psia and about 23 psia. The process uses a double column cryogenic air separation system for the production of oxygen from air which includes a higher pressure column and a lower pressure column, wherein a nitrogen-enriched fraction from the higher pressure column is condensed by indirect heat exchange in a reboiler-condenser that provides at least a fraction of the boilup at the bottom of the lower pressure column. Oxygen is withdrawn from the lower pressure column as a liquid and vaporized. One portion of air is feed air to the higher pressure column and a another portion of air is at least partially condensed by indirect heat exchange with the vaporizing oxygen. The latter portion of air is at least partially condensed at a pressure less than the pressure of the feed air to the higher pressure column.

Abstract: A pump for a cryogenic liquid, in particular liquid oxygen, includes a hydraulic motor which is supplied with a motor liquid under pressure and drives a wheel for pumping the cryogenic liquid, and relative sealing device preventing contamination of the cryogenic liquid by the motor liquid.

Abstract: Air is separated in a double rectification column comprising a higher pressure column and a lower pressure column, the latter operating at pressures of less than 2 bar absolute. An oxygen product is withdrawn from the column by a pump. A first vaporous nitrogen stream is taken from the top of the higher pressure column, is compressed in a compressor and is used in a gas turbine. Feed to the lower pressure column is derived from a stream of the bottom oxygen-enriched liquid fraction obtained in the higher pressure column. To this end, this stream is subjected to further separation (typically in further rectification column) to form a vaporous nitrogen fraction (a flow of which is condensed and is used as reflux in the lower pressure column) and an oxygen-containing feed to the lower pressure column which flows via an outlet and a condenser to the column. At least 60% of the nitrogen product flowing to the gas turbine is taken from the higher pressure column.

Abstract: A process delivers oxygen at a variable flow rate from a distillation system. The process uses a higher pressure column and a lower pressure column. The effects of oxygen product rate fluctuations on the distillation system are reduced by maintaining essentially constant flow rates within the columns.

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 for operating a cryogenic rectification column for the separation of the components of air by cryogenic rectification, whereby the column may be operated above its design capacity without encountering flooding, by passing vapor upward through the column at a flowrate which generates a pressure drop within the column of at least 0.7 inches of water per foot of packing height through a height of defined structured packing sheets having a structure in their bottom portion which differs from the structure in their middle portion and is the same as the structure in their top portion.

Abstract: In an integrated power generation system, part of the air from a gas turbine compressor is separated in a single nitrogen wash column to remove oxygen and the gaseous nitrogen produced at the top of the column is sent back to a point upstream of the expander of the gas turbine. The wash column may be fed with liquid nitrogen from an independent air separation unit in which air is separated. Liquid from the bottom of the wash column may be fed back to the air separation unit.

Abstract: Air is separated by cryogenic distillation comprising the steps of feeding compressed, cooled and purified air to a high pressure column where it is separated into a first nitrogen enriched stream at the top and a first oxygen enriched stream at the bottom. At least a portion of the first oxygen enriched stream is fed to an intermediate pressure column to yield a second nitrogen enriched stream at the top and a second oxygen enriched stream at the bottom. At least a portion of the second nitrogen enriched stream is sent to a low pressure column or to a top condenser of an argon column, and at least a portion of the second oxygen enriched stream is sent to the low pressure column. A third oxygen enriched stream is separated at the bottom and a third nitrogen enriched stream is separated at the top of the low pressure column. A heating gas is sent to a bottom reboiler of the low pressure column, and at least a portion of the third oxygen enriched stream is removed at a removal point.

Abstract: In a process for the production of a pressurized gaseous product by low-temperature separation of air, which is at times done in a gas operation and at times in a combined operation, whereby in the gas operation and in the combined operation (a) purified charging air is cooled under pressure, partially liquefied, and subjected to rectification to produce gaseous and liquid fractions, (b) extremely cold liquid of at least one of the liquid fractions from the rectification is evaporated under elevated pressure by indirect heat exchange with feed air, heated, and obtained as a pressurized gaseous product, whereby in combined operation, (c) the cold that is required for this purpose is generated in an air-refrigeration cycle, by air being compressed in the refrigeration cycle and work expanded, in which case heat is removed from the air, and the actively depressurized air that is partially in countercurrent is heated again with the charging air that is to be cooled and then repressurized, (d) extremely cold liqui

Abstract: In this air distillation plant (1) comprising a double column and a mixing column (5), the medium-pressure column (2), the low-pressure column (3) and the mixing column (5) are placed one on top of another, forming a single erected structure. Application to the supply of impure oxygen for the iron and steel industry.

Abstract: A cryogenic air separation system wherein product oxygen may be produced effectively at a higher production rate and at a lower production rate than the nominal production rate by employing a liquid oxygen storage tank and, in addition, an oxygen-enriched liquid storage tank operating in conjunction with the higher pressure column sump.

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: A cryogenic air separation system for producing very high purity oxygen employing a lower pressure column having a volume in its lower portion set off by a diaphragm, and an upgrader column communicating with the lower pressure column in a defined manner relative to the diaphragm.