US3605423A - Air rectification with multiple reboilers and condensers - Google Patents

Air rectification with multiple reboilers and condensers Download PDF

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Publication number
US3605423A
US3605423A US732670A US3605423DA US3605423A US 3605423 A US3605423 A US 3605423A US 732670 A US732670 A US 732670A US 3605423D A US3605423D A US 3605423DA US 3605423 A US3605423 A US 3605423A
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Prior art keywords
column
condensers
oxygen
air
reboilers
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US732670A
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English (en)
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Roman Stoklosinski
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    • 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
    • F25J3/04248—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion
    • F25J3/04333—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using quasi-closed loop internal vapor compression refrigeration cycles, e.g. of intermediate or oxygen enriched (waste-)streams
    • F25J3/04351—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using quasi-closed loop internal vapor compression refrigeration cycles, e.g. of intermediate or oxygen enriched (waste-)streams of 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
    • 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
    • F25J3/044—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 single pressure main column system only
    • 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
    • F25J3/04769—Operation, control and regulation of the process; Instrumentation within the process
    • F25J3/04854—Safety aspects of operation
    • F25J3/0486—Safety aspects of operation of vaporisers for oxygen enriched liquids, e.g. purging of liquids
    • 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
    • F25J2200/00—Processes or apparatus using separation by rectification
    • F25J2200/50—Processes or apparatus using separation by rectification using multiple (re-)boiler-condensers at different heights of the column
    • 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
    • F25J2200/00—Processes or apparatus using separation by rectification
    • F25J2200/76—Refluxing the column with condensed overhead gas being cycled in a quasi-closed loop refrigeration cycle
    • 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
    • F25J2205/60—Processes or apparatus using other separation and/or other processing means using adsorption on solid adsorbents, e.g. by temperature-swing adsorption [TSA] at the hot or cold end
    • 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
    • F25J2270/00—Refrigeration techniques used
    • F25J2270/02—Internal refrigeration with liquid vaporising loop
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S62/00—Refrigeration
    • Y10S62/90—Triple column

Definitions

  • At least a part of the gaseous top fraction and at least a part of the feed are used as the heating medium in reboilers, and at least part of the liquidbottom fraction is used as the cooling medium in at least one condenser positioned above the highest reboiler.
  • This invention relates to improvements in or relating to gas separation, and is especially concerned with the separation of air by fractional distillation to obtain an oxygen product.
  • a method of fractional distillation in which a feed, normally air, is introduced into a distillation column having distributed at intervals up its height a number of reboilers and condensers which are arranged so as to work the column ap proximately reversibly and obtain a liquid bottom fraction, normally oxygen, and a gaseous top fraction, normally nitrogen, at least a part of the gaseous top fraction and at least a part of the feed being used as the heating medium in the or each reboiler, and at least part of the liquid bottom fraction being used as the cooling medium in at least one condenser, positioned above the highest reboiler.
  • the method according to the invention is extremely simple and because the column is worked approximately reversibly it is eflicient.
  • a part of the gaseous top fraction is compressed, cooled and then used as the heating medium in a reboiler where it condenses and it is then throttled before it is returned to the top of the column, and a part of the air feed is compressed, cooled and then used as the heating medium in another reboiler where it condenses, and it is then throttled and fed to the column.
  • the liquid oxygen product is withdrawn from the column, is throttled or is divided into two or more streams throttled to different pressures, and the or each stream is passed through one of the column condensers before it constitutes the oxygen product.
  • the invention also includes a plant for operating in accordance with the above method.
  • Atmospheric air is drawn into the plant through a filter 10 and is compressed in a compressor 12 to the low excess pressure required to overcome friction losses within the 3,695,423 Patented Sept. 20, 1971 plant.
  • the compression step causes heating of the air and it is therefore cooled in an after cooler 16 by heat exchange with at least a part of the oxygen product (not shown), and then with the nitrogen product stream. Finally it is cooled to about 40 F. in a refrigerator 18 so as to condense water vapour and thereby assist in the drying of the air.
  • the refrigeration necessary to operate the refrigerator 18 can be obtained from an outside source.
  • the cooled air is next purified by passing it through one of a pair of alternately operating driers 20.
  • Each drier has an upper bed of desiccant, for example silica gel, and a lower bed of molecular sieves. Most of the water vapour is absorbed in the upper bed of silica gel while the molecular sieves serve to absorb the remainder of the moisture and also the carbon dioxide in the air. The purification of the air in this way ensures eflicient and uninterrupted running of the plant.
  • desiccant for example silica gel
  • molecular sieves serve to absorb the remainder of the moisture and also the carbon dioxide in the air.
  • the clean dry carbon dioxide free air from the driers is passed through a heat exchanger 22 in which it is cooled to a temperature near its dew point by heat exchange with the products from the distillation column 24.
  • the cooled air is then fed to an intermediate position in the column 24, and it is separated into a top nitrogen product and a bottom oxygen product.
  • the column 24 is run approximately reversibly by having distributed throughout its length a number of reboilers 26 and 27 and condensers 28 and 29 to add and remove heat and so provide reboiling and reflux at various points up the height of the column.
  • the distribution of reflux is obtained using streams of nitrogen and oxygen products and air in conjunction with three compressors 30 to 32.
  • a still better approach to reversible operation could be obtained by employing more reboilers and condensers and more compressors. In practice, however, it is not usually necessary or economical to use more than are shown.
  • the gaseous nitrogen top product is taken from the column to the heat exchanger 22 to cool the incoming air and then some of the nitrogen is fed to the compressor 30 where it is compressed to a medium pressure and returned to the heat exchanger for cooling, while the remainder of the nitrogen is led first to the cooler 16 m is then passed through the drier 20 which is not being used to reactivate it.
  • the compressed nitrogen returned to the heat exchanger is cooled to near its dew point at that pressure and it is then taken to the reboiler 27 where it condenses in heat exchange with boiling reflux inside the column.
  • the condensate is then throttled through a valve 34 to the pressure inside the column and is itself introduced at the top of the column as reflux.
  • the purified air from the driers 20 is split into two streams. As previously described, the larger stream is fed directly to the column through the heat exchanger 22. The other stream is compressed in the compressor 32 before being passed through the heat exchanger 22 and introduced into the reboiler 26. There it condenses in heat contact with the boiling reflux passing down the column, and the condensed liquid is throttle through a valve 36 to the pressure in the column and introduced near the top of the column as reflux.
  • Liquor oxygen product in the sump of the column is removed by a line 38 and divided into two streams which are throttled in valves 40 and 42 to a lower pressure, the valve 40 being arranged to throttle its stream to a lower pressure than the valve 2.
  • the streams from the valves 40 and 42 are fed respectively to the condensers 29 and 28 and both liquid streams vaporise in these boilers by heat contact with the vapours in the column, part of which are condensed for reflux.
  • the oxygen vapour product streams are taken from the condensers 28 and 29 to the heat exexchanger 22 and the after cooler 16 where they are warmed to ambient temperatures and passed to a compressor 31 which restores the streams to atmospheric pressure and also combines the streams. Part of the gaseous product from the compressor 31 is returned via the heat exchanger 22 to the sump of the column while the balance constitutes the oxygen product.
  • the oxygen stream from the sump could have been divided into more than two streams which would pass through more than two condensers.
  • a small stream of liquid oxygen is withdrawn alternately from one or other or from both condensers by a lift pump 44 and circulated through one of a pair of alternately operating purifiers 46.
  • the purifier not being used is reactivated by passing through it a stream of nitrogen product.
  • the purified oxygen stream is returned to the condenser or condensers.
  • the plant can also be made to produce pure nitrogen by withdrawing a stream of impure nitrogen gas from near to the top of the column .as a third stream and venting this to the atmosphere as a waste purge.
  • a liquid oxygen product can also be produced or both liquid and gaseous products can be produced by withdrawing from the plant oxygen liquid from the sump.
  • the necessary extra refrigeration for the process can then be introduced at the condensers where the sump liquid is normally vaporized by withdrawing part of the vapours from the column at that point, condensing them in an auxiliary refrigerator and then returning them to the column at the same level, or by other suitable means.
  • the plant just described is relatively simple and yet is eflicient.
  • the column is operated substantially reversibly and its operation need require only three compressors compared with the six preferred for the column shown in my Pat. No. 1,006,499. Also the amount of nitrogen stream handled by the compressor 30 need not be more than 30% of the initial air feed.
  • a method of fractionally distilling the air comprising the steps of:
  • a method according to claim 1 further comprising dividing said liquid oxygen into two streams, throttling each stream to different lower pressures, passing each stream to one condenser as the cooling medium, compressing said streams from said condensers to the same pressure and combining said stream to give the product oxygen gas.
  • a method according to claim 1 further comprising the steps of withdrawing oxygen gas from the lower part of said column, compressing said gas, passing said gas through a sump reboiler in which it becomes substantially completely condensed, and returning said condensed oxygen to the lower part of said column as liquid reflux.
  • a method according to claim 1 further comprising the steps of throttling a part of the liquid oxygen bottom product and evaporating it in a condenser positioned in the lower part of the column to provide a liquid reflux in that part of the column.
  • a plant for the fractional distillation of air to separate the air into oxygen and nitrogen products comprising:
  • (j) means for removing said bottom liquid oxygen fraction and dividing it into a plurality of oxygen portions, means for throttling each of said plurality of portions to a different pressure and passing each throttled oxygen portion through.
  • one of said plurality of condensers positioned in said column means for passing each of said plurality of a portion from said condensers through said heat exchanger to cool said first and second supplies of air, and means for compressing said plurality of a portion from said heat exchanger to provide oxygen product gas.
  • a plant according to claim 6 having two reboilers, means for dividing said bottom liquid oxygen fraction into first and second parts, first throttling means for reducing the pressure of said first part, second throttling means for reducing the pressure of said second part to a lower pressure than said first part, means for passing said throttled first part to the lower of said two reboilers, means for passing said throttled second part to the upper of said two boilers, means for passing both parts from said reboilers through said heat exchanger, and means for compressing both parts to the same pressure and combining them to provide product oxygen gas.
  • a plant according to claim 7 further comprising means for returning part of said product oxygen gas to said column.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Separation By Low-Temperature Treatments (AREA)
US732670A 1967-06-01 1968-05-28 Air rectification with multiple reboilers and condensers Expired - Lifetime US3605423A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB25441/67A GB1182615A (en) 1967-06-01 1967-06-01 Improvements in or relating to the Separation of Mixtures of Gases

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US3605423A true US3605423A (en) 1971-09-20

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US (1) US3605423A (enrdf_load_stackoverflow)
DE (1) DE1751450A1 (enrdf_load_stackoverflow)
FR (1) FR1570115A (enrdf_load_stackoverflow)
GB (1) GB1182615A (enrdf_load_stackoverflow)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3813890A (en) * 1969-07-02 1974-06-04 B Bligh Process of continuous distillation
US4088464A (en) * 1975-03-26 1978-05-09 S.I.A.D. Societa Italiana Acetilene E Derivati Method and apparatus with a single rectifying column for air fractionation
US5263327A (en) * 1992-03-26 1993-11-23 Praxair Technology, Inc. High recovery cryogenic rectification system
US5656065A (en) * 1995-10-04 1997-08-12 Air Products And Chemicals, Inc. Multibed pressure swing adsorption apparatus and method for the operation thereof
US5682764A (en) * 1996-10-25 1997-11-04 Air Products And Chemicals, Inc. Three column cryogenic cycle for the production of impure oxygen and pure nitrogen
US6568209B1 (en) * 2002-09-06 2003-05-27 Praxair Technology, Inc. Cryogenic air separation system with dual section main heat exchanger
RU2229070C1 (ru) * 2003-07-31 2004-05-20 Сыропятов Владимир Павлович Устройство и способ получения инертной газовой смеси на основе азота
RU2252378C1 (ru) * 2003-12-22 2005-05-20 Открытое акционерное общество "Уральский компрессорный завод" Способ получения и сжатия азотно-воздушной смеси и устройство для его осуществления

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2535488A1 (de) * 1975-08-08 1977-02-10 Linde Ag Verfahren und vorrichtung zur tieftemperaturzerlegung von luft

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3813890A (en) * 1969-07-02 1974-06-04 B Bligh Process of continuous distillation
US4088464A (en) * 1975-03-26 1978-05-09 S.I.A.D. Societa Italiana Acetilene E Derivati Method and apparatus with a single rectifying column for air fractionation
US5263327A (en) * 1992-03-26 1993-11-23 Praxair Technology, Inc. High recovery cryogenic rectification system
US5656065A (en) * 1995-10-04 1997-08-12 Air Products And Chemicals, Inc. Multibed pressure swing adsorption apparatus and method for the operation thereof
US5682764A (en) * 1996-10-25 1997-11-04 Air Products And Chemicals, Inc. Three column cryogenic cycle for the production of impure oxygen and pure nitrogen
US6568209B1 (en) * 2002-09-06 2003-05-27 Praxair Technology, Inc. Cryogenic air separation system with dual section main heat exchanger
RU2229070C1 (ru) * 2003-07-31 2004-05-20 Сыропятов Владимир Павлович Устройство и способ получения инертной газовой смеси на основе азота
RU2252378C1 (ru) * 2003-12-22 2005-05-20 Открытое акционерное общество "Уральский компрессорный завод" Способ получения и сжатия азотно-воздушной смеси и устройство для его осуществления

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Publication number Publication date
FR1570115A (enrdf_load_stackoverflow) 1969-06-06
GB1182615A (en) 1970-02-25
DE1751450A1 (de) 1971-07-08

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