GB2181528A - Air separation - Google Patents

Air separation Download PDF

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Publication number
GB2181528A
GB2181528A GB08524080A GB8524080A GB2181528A GB 2181528 A GB2181528 A GB 2181528A GB 08524080 A GB08524080 A GB 08524080A GB 8524080 A GB8524080 A GB 8524080A GB 2181528 A GB2181528 A GB 2181528A
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United Kingdom
Prior art keywords
nitrogen stream
nitrogen
impurity
laden
air
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB08524080A
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GB2181528B (en
GB8524080D0 (en
Inventor
Michael Ernest Garrett
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
BOC Group Ltd
Original Assignee
BOC Group Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by BOC Group Ltd filed Critical BOC Group Ltd
Priority to GB8524080A priority Critical patent/GB2181528B/en
Publication of GB8524080D0 publication Critical patent/GB8524080D0/en
Priority to ZA867376A priority patent/ZA867376B/en
Priority to JP61233122A priority patent/JP2773858B2/en
Publication of GB2181528A publication Critical patent/GB2181528A/en
Application granted granted Critical
Publication of GB2181528B publication Critical patent/GB2181528B/en
Expired legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/22—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by diffusion
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04636—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air using a hybrid air separation unit, e.g. combined process by cryogenic separation and non-cryogenic separation techniques
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04763—Start-up or control of the process; Details of the apparatus used
    • F25J3/04866—Construction and layout of air fractionation equipments, e.g. valves, machines
    • F25J3/04969—Retrofitting or revamping of an existing air fractionation unit
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2205/00—Processes or apparatus using other separation and/or other processing means
    • F25J2205/24—Processes or apparatus using other separation and/or other processing means using regenerators, cold accumulators or reversible heat exchangers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2205/00—Processes or apparatus using other separation and/or other processing means
    • F25J2205/80—Processes or apparatus using other separation and/or other processing means using membrane, i.e. including a permeation step
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2230/00—Processes or apparatus involving steps for increasing the pressure of gaseous process streams
    • F25J2230/42—Processes or apparatus involving steps for increasing the pressure of gaseous process streams the fluid being nitrogen
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2240/00—Processes or apparatus involving steps for expanding of process streams
    • F25J2240/02—Expansion of a process fluid in a work-extracting turbine (i.e. isentropic expansion), e.g. of the feed stream
    • F25J2240/12—Expansion of a process fluid in a work-extracting turbine (i.e. isentropic expansion), e.g. of the feed stream the fluid being nitrogen

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Separation By Low-Temperature Treatments (AREA)
  • Separation Using Semi-Permeable Membranes (AREA)

Abstract

In a cryogenic air separation plant, a reversing heat exchanger has switching passes 4 and 6 for an incoming air stream and a "waste" nitrogen stream, and a pass 8 for product nitrogen. As shown in the drawing, water vapour and carbon dioxide previously deposited in pass 6 are resublimed by the waste nitrogen stream. The resulting impurity laden nitrogen stream is compressed in compressor 10 and purified in membrane separator 18. The resultant purified nitrogen stream may be expanded in an expansion turbine 24. The yield of nitrogen from an air separation plant may thus be increased. If desired, the membrane separator 18 may be retro-fitted to a cryogenic air separation plant. <IMAGE>

Description

SPECIFICATION Air separation This invention relates to air separation. In particular, it relates to the method and apparatus for the separation of air at cryogenic temperatures which employ at least one reversing heat exchanger.
Cryogenic air separation plants are well known and widely used in industry to produce one or more of nitrogen, oxygen and argon as products. Am example of a cryogenic air separation plant is the one described in UK patent specification No. 1 258 568. In such a plant, the air is purified orcooledto a chosen cryogenictemperature. It is then fractionated to produce substantially pure nitrogen and oxygen, and, in the example ofthe plant in the aforesaid UK patent specification, argon. There are three main methods of purifying the air in orderto extract carbon dioxide and water vapour.In one method, part of the purification ofthe air is carried out in at least one reversing heat exchanger. In the reversing heat exchanger or heat exchangers, the air is progressively cooled and impurities such as water vapour are deposited as frozen particles on the heat exchange surfaces that contacttheairbeing cooled. The reversing heat exchanger or heat exchangers are provided with passagesfora waste nitrogen stream (containing some oxygen impurity) which flows countercurrentlyto the air stream and is employed to eva po rate the frozen impurities.When the level of impurity in the heatexchangepassagesthroughwhichtheair passes has reached a chosen level, the air passage is switched with the waste nitrogen passage so as to effect this removal of the impurities. After passage through the reversing heat exchanger or heat exchangers, the waste nitrogen stream is vented to the atmosphere. In another method, not now commonly used, a plurality of regenerators is employed. The air to be cooled is passed through one regeneratorand the waste nitrogen stream through the other for a given period, after which the flows are switched over,the air now passing through the regenerator which had previously been cooled by the return product stream. The regenerators are provided with suitable packing to enable "cold" to be stored.Carbon dioxide and watervapour are deposited as solids from the air being cooled and are then resublimed in the waste nitrogen stream.
In a third method, a temperature swing molecular sieve purification unit is employed. Carbon dioxide and water vapour are adsorbed from compressed air that has been freed from any drops of liquid water in at least one bed of molecular sieve adsorbent, while the remaining beds are being regenerated. After a chosen time the beds are switched. Regeneration is typically effected by heating at least part of the waste nitrogen stream and passing it through the molecular sieve adsorbent whereby to effect desorption of the watervapour, carbon dioxide and any other adsorbed impurities.
In each of these methods, therefore, there is formed a waste nitrogen stream typically containing in the order of 1% by volume of oxygen and being laden with the impurities that are removed by the stream from the air purification unit. Typically, the waste nitrogen stream may comprise in the order of 35% by volume of the nitrogen produced as product in the airseparation plant. Asthe demandfornit rogen has, over the years, increased, so there has been a need to increase the yield of nitrogen from such air separation plant.
Accordingly, the method and apparatus according to the invention, in its broadest aspect, purify the im purity-laden stream.
The invention thus provides a method of separat ing air including the steps of extracting watervapour and carbon dioxide from the air in an extraction means, cooling the airto a cryogenictemperature and subjecting it to fractionation to produce oxygen and nitrogen products and a nitrogen stream whose concentration of oxygen is greaterthan that of the nitrogen product, employing at least some of said nitrogen stream to purge watervapour and carbon dioxide from the extraction means, and subjecting at least some of the resulting impurity-laden nitrogen stream to purification.
The invention also provides apparatusforseparating air, including means for extracting watervapour and carbon dioxide from the air, meansforcooling the airto a cryogenic temperature, at least onefractionation column operable to produce oxygen and nitrogen products and a nitrogen stream whose concentration of oxygen is greater than that ofthe nitrogen product, means for passing at least some of the nitrogen stream through said extraction means to purge said watervapourand carbon dioxide therefrom, and meansfor purifying the resulting impurityladen nitrogen stream.
The extraction means is preferably constituted by at least one reversing heat exchanger in which at least part of the cooling ofthe air is performed, water vapour and carbon dioxide thus being deposited as solids and subsequently resublimed by the nitrogen stream.
The impurity-laden nitrogen stream is with advantage purified by membrane separation. Membranes capable of separating oxygen, watervapour and carbon dioxide from nitrogen are known and commercially available. One or more stages of mem braneseparation may be employed depending on the concentration of oxygen that is desired for the purified waste stream. It is generally preferred that the nitrogen stream priorto purification contains 1% byvolumeofoxygen or less.
Alternatively, pressure swing adsorption may be employed to purify the nitrogen stream.
The impurity-laden nitrogen stream is preferably compressed, desirablyto a pressure in the range 10 to 30 atmospheres, upstream of membrane separation. Water that is thus condensed in the compressor or any after-cooler associated therwith, may be drained off prior to entry of the nitrogen stream into the membrane separation means. Since the purified nitrogen stream is the non-permeate stream, it will be subjected to a only a relatively small pressure drop in the membrane separator. It is accordingly possible to recover some of the work done bythe compression means in an expansion turbine which is typically employed to drive the compressor (or an other compressor).If desired, the refrigeration resulting from the work-expansion of the purified nitrogen stream may be employed in the heat exchange system of the air separation plant or in an associated liquefier.
If desired, the means for purifying the impurityladen nitrogen stream may be retro-fitted to an existing airseparation plant.
The concentration of water and carbon dioxide in the impurity-laden nitrogen stream is not constant throughout regeneration of such reversing heat exchanger. In orderto keep down the rate at which nitrogen enters the permeate stream ofthe membrane separator during periods of operation when the concentration of water and carbon dioxide is lower than average, the pressure at which the nitrogen stream is fed to the membrane separator may be varied. Alternatively, the rate at which the impurity-laden nitrogen stream is fed to the membrane separator may be varied by venting a portion of such stream typically downstream of its exit from the reversing heat exchanger or exchangers. Alternatively, or in addition, the impurity-laden nitrogen stream may pass into a buffervessel upstream ofthe purifying means.
The method and apparatus according to the invention will now be described by way of example with reference to the accompanying drawing which is a schematic representation of a purification unit in flow communication relationship with a reversing heatexchangerforming partofairseparation plant.
Referring to the drawing, there is shown a reversing heat exchanger 2 having passes 4, 6 and 8for respectively an air stream to be separated, a nitrogen stream including typically 1% by volume of oxygen impurity and a relatively pure nitrogen product stream. The reversing heat exchanger2 has means not shown for switching passes4and 6. Such means are entirely conventional, and will therefore not be described in detail herein. The impurity-laden nitrogen pass communicates with the inlet of a compressor 10 having an after-cooler 12 fitted with a drain 14for condensed water. The outletside ofthe compressor 10 communicates via the after cooler 12 with a membrane separator 18 having an outlet 20 for non-permeate gas and an outlet 22 for permeate gas.
The outlet22 communicates with the inlet of an expansion turbine 24which is typically employed to drive the compressor 10.
In operation, the impure nitrogen stream passing through the reversing heat exchanger 2 evaporates solid impurities previously deposited by the air stream. The solid impurities comprise solid carbon dioxide and ice. The resulting impurity-laden nitrogen stream is compressed in compressor 10 to a pressure in the range 10 to 30 atmospheres absolute is cooled in the after cooler 12, with resultant condensed water being drained offthrough drain 14, and enters the membrane separator 18. A permeate stream comprising at least 90% of the oxygen impurity in the impurity-laden nitrogen entering the separator 18, and substantially all thewatervapour and carbon dioxide impurities in such nitrogen, and some of its nitrogen content as well, is formed and leaves the pla nt throug h the outlet 22.The remaining gas, consisting of substantially pure nitrogen, leaves the separatorthrough the outlet 20 and is expanded to a lower pressure in the expansion turbine 24. The gas may then be taken as product from the outlet of the expansion turbine 24 via a pipeline (not shown) to a plant in which itisto be used (forexampletocreate a non-reactive atmosphere). If the nitrogen is required at high pressure, for example if it is to be liquefied or used to fill cylinders, the expansion turbine 24 may be omittedfrom the plantshown in Figure 1.
The apparatus may additionally include an adsorber or absorberfor removing any traces of hydrocarbon from the nitrogen stream upstream or downstream of the membrane separator 18.
In one example of the invention,the reversing heat exchanger may be used as the reversing heat exchanger6a as shown in the drawing accompanying UK patent specification 1 258568 and described therein. Thus, the membrane separator and associa- ted compressor and expansion turbine may, if desired, be retro-fitted to the air separation plant shown in the drawing accompanying UK patent specification 1 258 568. It is to be appreciated that although the aforesaid UK patent specification describes an air separation plant employing a single rectification column with a side columnforseparating argon,the method and apparatus according to this invention are equally suitable for use in conjunction with air separation plants employing double rectification columns (with orwithout argon side columns) or air separation plants producing having a single column producing just oxygen and nitrogen product.

Claims (16)

1 . A method of separating air including the steps of extracting water vapour and carbon dioxide from the air in an extraction means, cooling the airto a cryogenictemperature and subjecting it to fractionation to produce oxygen and nitrogen products and a nitrogen stream whose concentration of oxygen is greater than that of the nitrogen product, employing at least some of said nitrogen stream to purgewater vapour and carbon dioxidefrom the extraction means, and subjecting at least some of the resulting impurity-laden nitrogen stream to purification.
2. A method as claimed in claim 1, in which the extraction means is constituted by at least one reversing heatexchanger in which at least partofthe cooling of the air is performed, watervapourand carbon dioxide thus being deposited as solids and subsequently resublimed by the nitrogen stream.
3. A method as claimed in claim 1 or claim 2, in which the impurity-laden is purified by membrane separation.
4. A method as claimed in claim 3, in which the impurity-laden nitrogen stream is compressed upstream of membrane separation.
5. A method as claimed in claim 4, in which the impurity-laden nitrogen stream is compressed to a pressure in the range 1 Oto 30 atmospheres.
6. A method as claimed in claim 4 or claim so in which the purified nitrogen stream is work-expanded downstream of the membrane separator.
7. A method as claimed in claim 1 or claim 2, in which the impurity-laden nitrogen stream is purified by pressure swing adsorption.
8. A method as claimed in any one of the preced- ing claims, in which the impurity-laden nitrogen stream contains 1% by volume or less of oxygen.
9. A method of separating air substantially as described herein with reference to the accompanying drawing.
10. Apparatus for separating air, including meansforextractingwatervapourandcarbon dioxide from the air, meansforcooling the airto a cryogenic temperature, at least one fractionation column operable to produce oxygen and nitrogen products and a nitrogen stream whose concentration of oxygen is greaterthan that of the nitrogen product, means for passing at least some of the nitrogen stream through said extraction means to purge said water vapour and carbon dioxide therefrom, and means for purifying the resulting impurity-laden nitrogen stream.
11. Apparatus as claimed in claim 10, in which the extraction means is constituted by at least one reversing heat exchanger, in which, in operation, at least part of the cooling of the air is performed.
12. Apparatus as claimed in claim 11, in which the purification means comprises a membrane separator.
13. Apparatus as claimed in claim 12, additionally including a compressorforthe impurity-laden nitrogen stream upstream ofthe membrane separator.
14. Apparatus as claimed in claim 13, additionally including an expansion turbine forwork-expanding the purified nitrogen stream.
15. Apparatus as claimed in claim 11, in which the purification means operates by pressure swing adsorption.
16. Apparatus for separating air, substantially as herein described with reference to the accompanying drawing.
GB8524080A 1985-09-30 1985-09-30 Air separation Expired GB2181528B (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
GB8524080A GB2181528B (en) 1985-09-30 1985-09-30 Air separation
ZA867376A ZA867376B (en) 1985-09-30 1986-09-26 Air separation
JP61233122A JP2773858B2 (en) 1985-09-30 1986-09-30 Method and apparatus for separating air

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB8524080A GB2181528B (en) 1985-09-30 1985-09-30 Air separation

Publications (3)

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GB8524080D0 GB8524080D0 (en) 1985-11-06
GB2181528A true GB2181528A (en) 1987-04-23
GB2181528B GB2181528B (en) 1989-09-06

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GB (1) GB2181528B (en)
ZA (1) ZA867376B (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0397192A2 (en) * 1989-05-12 1990-11-14 Praxair Technology, Inc. Dry, high purity nitrogen production process and apparatus
US5352272A (en) * 1991-01-30 1994-10-04 The Dow Chemical Company Gas separations utilizing glassy polymer membranes at sub-ambient temperatures
US5837032A (en) * 1991-01-30 1998-11-17 The Cynara Company Gas separations utilizing glassy polymer membranes at sub-ambient temperatures
EP1181968A2 (en) * 2000-08-21 2002-02-27 Praxair Technology, Inc. Gas separation process using ceramic membrane and regenerators

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB594958A (en) * 1943-08-28 1947-11-24 Linde Air Prod Co Improvement in process of and apparatus for producing compressed oygen or other gas by liquifaction
GB1258568A (en) * 1968-08-21 1971-12-30
EP0144430A1 (en) * 1983-03-08 1985-06-19 Daidousanso Co., Ltd. Apparatus for producing high-purity nitrogen gas

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB594958A (en) * 1943-08-28 1947-11-24 Linde Air Prod Co Improvement in process of and apparatus for producing compressed oygen or other gas by liquifaction
GB1258568A (en) * 1968-08-21 1971-12-30
EP0144430A1 (en) * 1983-03-08 1985-06-19 Daidousanso Co., Ltd. Apparatus for producing high-purity nitrogen gas

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0397192A2 (en) * 1989-05-12 1990-11-14 Praxair Technology, Inc. Dry, high purity nitrogen production process and apparatus
EP0397192A3 (en) * 1989-05-12 1991-01-23 Praxair Technology, Inc. Dry, high purity nitrogen production process and apparatus
US5352272A (en) * 1991-01-30 1994-10-04 The Dow Chemical Company Gas separations utilizing glassy polymer membranes at sub-ambient temperatures
US5679133A (en) * 1991-01-30 1997-10-21 Dow Chemical Co. Gas separations utilizing glassy polymer membranes at sub-ambient temperatures
US5837032A (en) * 1991-01-30 1998-11-17 The Cynara Company Gas separations utilizing glassy polymer membranes at sub-ambient temperatures
EP1181968A2 (en) * 2000-08-21 2002-02-27 Praxair Technology, Inc. Gas separation process using ceramic membrane and regenerators
EP1181968A3 (en) * 2000-08-21 2003-06-18 Praxair Technology, Inc. Gas separation process using ceramic membrane and regenerators

Also Published As

Publication number Publication date
GB2181528B (en) 1989-09-06
JPS62142985A (en) 1987-06-26
JP2773858B2 (en) 1998-07-09
ZA867376B (en) 1987-05-27
GB8524080D0 (en) 1985-11-06

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Effective date: 19990930