Abstract: Compressed, purified, vaporous air and liquid air streams are introduced into a higher pressure rectification column. A stream of oxygen-enriched liquid flows from an outlet of the higher pressure rectification column via a reboiler and an expansion valve into a vessel. The oxygen-enriched liquid is partially vaporised in a boiler located in the vessel. The residual liquid flows from the vessel and a condenser to a lower pressure rectification column in which oxygen and nitrogen products are separated. A stream of vapour flows from the boiler through an outlet from the vessel to a pipeline which leads the air back for compression with incoming air. A greater yield of oxygen, and, if separated, argon is made possible by this recycle.

Abstract: In a process for the production of gas under pressure by cryogenic distillation, the gas is produced by vaporizing (or pseudo-vaporizing) a liquid drawn off from a distillation column. In order to supply additional gas under pressure, a flow of a gas coming from an external source is at least partially liquefied, and the liquid thus formed is added to the liquid drawn off from the column before or after an optional pressurization step.

Abstract: A cryogenic rectification system having high recovery of both higher purity and lower purity oxygen which employs a side column having a bottom reboiler wherein feed air is partially condensed and the feed air vapor remaining after the partial condensation is turboexpanded prior to rectification.

Abstract: A cryogenic rectification system wherein additional stripping vapor for the lower pressure column of a double column is produced from higher pressure column bottoms and feed for the argon column is taken from the upper portion of the lower pressure column and first processed through a stripping column. Lower purity oxygen is recovered either directly from the lower pressure column or after first being processed in an auxiliary column which additionally produces higher purity oxygen.

Abstract: A cryogenic process for producing impure oxygen and/or substantially pure nitrogen utilizes a classic double column arrangement and an additional third column operating at a medium pressure, i.e. between the pressure of the higher pressure stage and the lower pressure stage of the double column system. A portion of the feed air is separated in the stages of the double column system, and another portion of the feed air is distilled in the medium pressure stage. Crude liquid oxygen from the higher pressure stage and/or the medium pressure stage is reduced in pressure and boiled in a reboiler/condenser at the top of the medium pressure column. The vaporized crude liquid oxygen from the top reboiler/condenser of the medium pressure column is subsequently introduced as a vapor feed to the lower pressure stage, which reduces irreversibilities of separation in the lower pressure stage.

Abstract: A cryogenic method and apparatus using a liquefier and a two stage distillation column capable of operating in two modes, namely a first mode of operation during which only liquid nitrogen is produced and a second mode of operation during which liquid nitrogen and liquid oxygen are produced. By adjusting the time of operation in each mode, any ratio of liquid nitrogen to liquid oxygen greater than the ratio achieved during the second mode of operation can be achieved. In the first mode of operation, a condenser is used to condense the lower pressure stage gaseous nitrogen into lower pressure stage nitrogen condensate. To condense the lower pressure stage gaseous nitrogen, either at least a portion of the crude oxygen liquid from the higher pressure stage, at least a portion of the oxygen-enriched liquid from the lower pressure stage, at least a portion of the liquefied air, or mixtures thereof, are introduced to the condenser.

Abstract: A cryogenic rectification system for producing oxygen and nitrogen employing a kettle liquid column which processes oxygen-enriched kettle liquid from a higher pressure column and which is reboiled by a fluid taken from below the top of the higher pressure column.

Abstract: For the method, air (103, 104) is fractionated in a medium-pressure column (6) and a low-pressure column (5). The sump heating (3) of the low-pressure column (5) is carried out with a second airflow (204), which is liquefied at the same time. An intermediate fraction (18) is taken from the low-pressure column (5) and evaporated in the head condenser (10) of the medium-pressure column (6). The thereby resulting vapor (19) is returned to the low-pressure column. In the event that impure oxygen is obtained, the second airflow (203, 204) is recompressed (202) upstream from the sump heating (3), external energy being supplied, to a pressure above that of the medium-pressure column, the pressure being relieved downstream from the sump heating (3) in a first pressure relief valve (208) to the pressure of the medium-pressure column (6).

Abstract: A high pressure combustion turbine is integrated with a double column cryogenic air separation system by cooling and purifying a portion of the compressed air from the combustion turbine compressor, work expanding a first portion of the resulting cooled air, and introducing the expanded air into the low pressure column. A second portion of the resulting cooled air is further cooled, throttled, and introduced into the high pressure column. A nitrogen product stream is returned to the turbine combustor, and a portion of the nitrogen product stream optionally is cooled, throttled, and recycled into the high pressure column. Preferably the higher pressure column operates at an absolute pressure which is about 20% to about 85% of the absolute pressure of the compressed air from the combustion turbine air compressor.

Abstract: Air is raised in pressure by a compressor and pre-purified by removal of impurities, particularly H.sub.2 O vapor and CO.sub.2, in an adsorption unit. The resulting air is cooled in a heat exchanger, and is subjected to a first rectification in a rectification column in which the air is separated into a nitrogen-rich fraction and an oxygen-rich fraction. A further oxygen fraction enriched in argon is subjected to a second rectification in which argon is separated from oxygen in a second rectification column. First and second argon products of different purity are withdrawn from the second rectification column through outlets thereof.

Abstract: A double column cryogenic rectification system for producing lower purity oxygen wherein a minor portion of the feed air is successively condensed in two vertically oriented stages within the lower pressure column before undergoing rectification.

Abstract: An air separation plant and process in which a first stream of compressed feed air is introduced in vapour state into a higher pressure rectification column and separated therein into nitrogen vapour and oxygen-enriched liquid air and a flow of the nitrogen vapour is condensed in condenser-reboiler. A flow of the oxygen-enriched liquid air is separated in a reboiled lower pressure rectification column into nitrogen-rich and oxygen-rich fractions. A first flow of the condensed nitrogen is employed as reflux in the higher pressure rectification column and a second flow of the condensed nitrogen is employed as reflux in the lower pressure rectification column. A flow of compressed feed air is expanded in expansion turbine with the performance of external work so as to create refrigeration for the process. Products of the separation include one or both of a gaseous nitrogen product taken from the higher pressure rectification column and a liquid nitrogen product.

Abstract: In order to precool a flow of gas to be distilled, before a purification stage, it is sent into an exchanger (5) where it is cooled by heating a flow of refrigerant (13B). At least a part of this refrigerant has its pressure reduced before cooling the unpurified gas and may be a fraction of the gas to be distilled or a product of the distillation. It is preferably a cycle gas of the system. This arrangement makes it possible to obviate a refrigerating unit.

Abstract: A stream of compressed air is purified in a unit by removal of carbon dioxide and water vapour. The air is cooled by passage through a heat exchanger to a temperature suitable for its rectification. The air is separated in a higher pressure rectifier into oxygen-enriched liquid and nitrogen vapour. A stream of the oxygen-enriched liquid is reduced in pressure and introduced into a phase separator provided with a reboiler with the result that further separation takes place and a liquid further enriched in oxygen and an intermediate vapour are formed. A stream of the further-enriched liquid is separated into oxygen and nitrogen in a lower pressure rectifier. A stream of the intermediate vapour is condensed in a condenser and is introduced into the lower pressure rectifier.

Abstract: A process is set forth for introducing a multicomponent liquid feed stream at pressure P.sub.2 into a distillation column operating at lower pressure P.sub.1. The process comprises removing a split stream from the feed stream, reducing its pressure and using the resulting stream to subcool the feed stream. After being subcooled, the feed stream is also reduced in pressure and both streams are fed to different stages of the distillation column. An important embodiment of the present invention is within the standard double column air separation cycle where the multicomponent liquid stream is the crude liquid oxygen stream from the bottom of the high pressure column which must be reduced in pressure prior to its introduction into the low pressure column.

Abstract: A cryogenic rectification system for producing lower purity gaseous oxygen and high purity oxygen employing a double column and an auxiliary column which upgrades lower pressure column bottom liquid or processes higher pressure column kettle liquid.

Abstract: Process for the production of oxygen by cryogenic distillation of a supply mixture containing oxygen and nitrogen in a double column (5) comprising a medium pressure column (6) and a low pressure column (7), in which there is partially condensed at least one fraction of the supply mixture in a condenser (8) by vaporization of liquid oxygen from the base of the low pressure column (7), said partially condensed mixture is sent to the medium pressure column (6), all the oxygen destined to form the gaseous production being withdrawn in liquid phase from the base of the low pressure column (7), and brought to its utilization pressure.

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: An air boiling dual column cryogenic rectification system for producing lower purity oxygen wherein a portion of the feed air is used to reboil the lower pressure column and then is partially condensed in a vertically oriented stage within the lower pressure column before undergoing rectification.

Abstract: A first flow of air is compressed in a first air compressor associated with a gas turbine and is purified in an adsorptive purification unit which separates water vapour and carbon dioxide from the air. The purified first flow of air is further compressed to a pressure at least 5 bar higher than that at which it is purified in a second air compressor whose outlet pressure is independent of fluctuations in the power output of the gas turbine, is cooled in a main heat exchanger, is passed through an expansion valve, and is introduced into a higher pressure rectification column. A second flow of air is compressed in a third air compressor which is independent of the gas turbine. The compressed second flow of air is purified in an adsorptive purification unit by the separation of water vapour and carbon dioxide therefrom. The purified second flow of air is cooled in the main heat exchanger and is introduced into the higher pressure rectification column.

Abstract: An air separation process of the "pumped" type, in which liquid oxygen is removed from a double distillation column and is pumped to a higher production pressure and then vaporized under that pressure. The incoming air is divided into several streams. A first stream is compressed to the medium pressure, cooled and sent to the double distillation column (7). A second stream is compressed above about 25 bars, but below its condensation pressure during vaporization of the liquid oxygen under pressure, then cooled to an intermediate temperature, at which a portion of the air continues its cooling and is liquified (in 20A), then expanded (in 21A) and sent to the double column, while the rest is work expanded (in 4). Use in large size installations for the production of oxygen.

Abstract: A cryogenic rectification system for producing gaseous oxygen and high purity nitrogen employing a double column and an auxiliary column which processes higher pressure column fluid.

Abstract: The present invention relates to a cryogenic process and apparatus for production of an oxygen product from air, characterized in that a multiple passage plate-fin heat exchanger having at least two sets of passages is used to effectuate the rectifying and stripping functions, wherein one set of passages comprises a continuous-contact rectification dephlegmator which rectifies the separator vapor and produces the enriched-nitrogen rectifier overhead and the crude liquid oxygen bottoms; wherein a second set of passages comprises a continuous-contact stripping dephlegmator which strips the oxygen-enriched liquid to produce the nitrogen-enriched stripper overhead and the oxygen product; wherein reflux of the rectification device and boilup for the stripping device is provided, at least in part, by indirect heat exchange between and along said two sets of passages, thereby producing a thermal link between the rectification dephlegmator and the stripping dephlegmator.

Abstract: Process and installation for the production of gaseous oxygen under pressure by cryogenic distillation of air in a double column (5) comprising a medium pressure column (6) and a low pressure column (7). Rich liquid from the medium pressure column is divided into first and second liquid fractions which are sent to different levels in the low pressure column (7). These different levels are both below the level of withdrawal of impure nitrogen from the low pressure column (7). A fluid enriched in argon is withdrawn from the low pressure column (7) and distilled in an argon column (16). Liquid enriched in oxygen is withdrawn from a lower portion of the low pressure column (7). The two fractions of rich liquid are cooled to different temperatures before being sent to the low pressure column (7). A portion of the supply air is blown into an intermediate level of the low pressure column (7) and the levels of injection of the rich liquid are not below this intermediate level.

Abstract: A cryogenic rectification system for producing nitrogen having a low argon content wherein the reflux ratio in the upper portion of the higher pressure column of a double column system is modified by withdrawing nitrogen vapor from below the top of the column, liquefying the withdrawn vapor, and returning the liquefied nitrogen to the column at or near the withdrawal point and below the top of the column.

Abstract: Air is compressed in a compressor, cooled in a main heat exchanger, partially condensed in a reboiler-condenser, introduced into a higher pressure rectifier, and separated therein into nitrogen and oxygen-enriched liquid. Resulting nitrogen is condensed in further reboiler-condensers. One part of the condensate is used as reflux in the higher pressure rectifier and another part as reflux in a lower pressure rectifier. A stream of oxygen-enriched liquid is withdrawn from the high pressure rectifier and sent to an intermediate pressure rectifier which is reboiled by one of the further reboiler-condensers and in which further nitrogen is separated. A stream of liquid further enriched in oxygen is withdrawn from the bottom of the intermediate pressure rectifier and is separated in the lower pressure rectifier and impure and pure oxygen products are withdrawn respectively therefrom.

Abstract: A cryogenic rectification system for producing elevated pressure gaseous oxygen wherein pressurized liquid oxygen is vaporized against pressurized working fluid which is then turboexpanded to form a dual phase stream having both vapor and liquid fractions.

Abstract: A stream of air is compressed in compressor and has water vapor and carbon dioxide removed therefrom in purification unit. A part of the resulting purified air is cooled by passage through heat exchanger and is employed to heat an intermediate reboiler in a lower pressure rectification column. The air flow from the reboiler passes into a higher pressure rectification column which supplies a stream of oxygen-enriched liquid air for separation in the lower pressure rectification column. Liquid nitrogen reflux for the higher pressure column is provided by taking nitrogen vapor from this column through an outlet and condensing it in another intermediate reboiler located above the reboiler in the lower pressure rectification column. The condensed nitrogen is returned to the top of the column.

Abstract: Process and installation for the production of variable flow rates of at least one pure component by fractionation of a mixture in a distillation apparatus (15), containing structured packing (17) and dimensioned to handle a nominal flow rate of the mixture at nominal pressure. To obtain higher production than the nominal production, there is increased proportionately to the ratio of the productions, the flow rate of the mixture distilled in the apparatus (15). Also increased is the operating pressure of the apparatus so as to increase the flooding limit of the apparatus under similar proportions. Preferably, the mixture is air. There is a compressor (3) for the mixture to be fractionated designed for nominal capacity and, upstream of the latter, a blower (1). Alternatively, there can be a compressor (3) for the mixture to be fractionated designed for maximum capacity.

Abstract: A cryogenic rectification system employing a double column and two auxiliary reboilers associated with one or two auxiliary columns wherein both lower purity oxygen and higher purity oxygen is produced.

Abstract: Process and installation for the production of gaseous oxygen and/or gaseous nitrogen under pressure, of the type in which the air is distilled in a double distillation column (10) comprising a low pressure column (12) operating under a low pressure, and a medium pressure column (11) operating under a medium pressure. All the air to be distilled is compressed (in 1,4) to at least one high pressure of air substantially greater than the medium pressure, and the compressed air is cooled to an intermediate temperature. A portion of it is expanded in a turbine (5) to the medium pressure, before introducing it into the medium pressure column (11). The non-work-expanded air is liquified, then introduced after expansion (in 19, 20), into the double column; and at least one liquid product withdrawn from the double column is brought to the production pressure, and this liquid product is vaporized by heat exchange with the air.

Abstract: In this process for the distillation of air, of the type with a liquid oxygen pump (14) and with the vaporization of liquid oxygen under pressure, there are used, in addition to a principal compressor (1), at least three further compressors (9 to 11 ), of which two (9, 10) are mounted in series and supply the heat exchange line with air at a high pressure of the vaporization of oxygen. Air is withdrawn between these two further compressors, expanded to the medium pressure and introduced at the base of the medium pressure column (5), and at least one (11) of the three further compressors consumes the mechanical energy developed by the turbine (12).

Abstract: A fluid mixture is separated by distillation in a two column system in which the feed is prefractionated in a first column having at least one separation stage above the feed and the prefractionator bottoms provides feed to a second column operating at a lower pressure. Cooling for condensing the overhead vapor of the first column is provided by heat exchange with flashed prefractionator bottoms or with an intermediate fluid in the second column. The two-column system is readily combined with a high pressure column in a three-column distillation system for separating air which is particularly useful for integration with a gasification combined cycle combustion turbine system. Optionally, three nitrogen products can be produced at three different pressures.

Abstract: Ultra-pure nitrogen is produced in a process comprising separating air in an integrated plurality of columns. A nitrogen-enriched stream is elevated in pressure and thereafter contaminants and impurities are removed in an auxiliary column system which allows for the main column to efficiently operate below the required nitrogen product pressure, while including an ability to optionally obtain a normal purity nitrogen and a liquid nitrogen product. The process and installation remains efficient and economical in a relatively small scale installation to produce extremely pure nitrogen product.

Abstract: An air separation method and apparatus in which a stream of air is compressed in a compressor and purified in a unit. One stream of the resulting air is cooled in a heat exchanger and is separated in an arrangement of rectification columns comprising a higher pressure rectification column, a lower pressure rectification column, and a further rectification column for separating argon from an argon-enriched oxygen stream withdrawn from the lower pressure rectification column and the stream of resulting air is introduced into the higher pressure rectification column through an inlet. A second cooled, compressed, purified air stream is expanded in an expansion turbine and is introduced into the lower pressure rectification column. A third cooled, compressed, purified air stream is expanded in a second expansion turbine and is introduced into the higher pressure rectification column.