US20220074656A1 - Apparatus and method for separating air by cryogenic distillation - Google Patents

Apparatus and method for separating air by cryogenic distillation Download PDF

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US20220074656A1
US20220074656A1 US17/416,782 US201917416782A US2022074656A1 US 20220074656 A1 US20220074656 A1 US 20220074656A1 US 201917416782 A US201917416782 A US 201917416782A US 2022074656 A1 US2022074656 A1 US 2022074656A1
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column
flow
pressure
air
heat exchanger
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Benoit Davidian
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LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
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LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
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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
    • F25J3/04006—Providing pressurised feed air or process streams within or from the air fractionation unit
    • F25J3/04078—Providing pressurised feed air or process streams within or from the air fractionation unit providing pressurized products by liquid compression and vaporisation with cold recovery, i.e. so-called internal compression
    • F25J3/0409—Providing pressurised feed air or process streams within or from the air fractionation unit providing pressurized products by liquid compression and vaporisation with cold recovery, i.e. so-called internal compression of oxygen
    • 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
    • F25J3/04151—Purification and (pre-)cooling of the feed air; recuperative heat-exchange with product streams
    • F25J3/04163—Hot end purification of the feed air
    • F25J3/04169—Hot end purification of the feed air by adsorption of the impurities
    • 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
    • F25J3/04151—Purification and (pre-)cooling of the feed air; recuperative heat-exchange with product streams
    • F25J3/04187—Cooling of the purified feed air by recuperative heat-exchange; Heat-exchange with product streams
    • F25J3/04193—Division of the main heat exchange line in consecutive sections having different functions
    • F25J3/04206—Division of the main heat exchange line in consecutive sections having different functions including a so-called "auxiliary vaporiser" for vaporising and producing a gaseous product
    • 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
    • F25J3/04151—Purification and (pre-)cooling of the feed air; recuperative heat-exchange with product streams
    • F25J3/04187—Cooling of the purified feed air by recuperative heat-exchange; Heat-exchange with product streams
    • F25J3/0423—Subcooling of liquid process streams
    • 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
    • F25J3/04254—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using the cold stored in external cryogenic fluids
    • 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
    • F25J3/04284—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using internal refrigeration by open-loop gas work expansion, e.g. of intermediate or oxygen enriched (waste-)streams
    • F25J3/0429—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using internal refrigeration by open-loop gas work expansion, e.g. of intermediate or oxygen enriched (waste-)streams of feed air, e.g. used as waste or product air or expanded into an auxiliary column
    • F25J3/04303—Lachmann expansion, i.e. expanded into oxygen producing or low pressure 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
    • 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
    • F25J3/04284—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using internal refrigeration by open-loop gas work expansion, e.g. of intermediate or oxygen enriched (waste-)streams
    • F25J3/04309—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using internal refrigeration by open-loop gas work expansion, 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
    • F25J3/04406—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 dual pressure main column system
    • F25J3/04412—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 dual pressure main column system in a classical double column flowsheet, i.e. with thermal coupling by a main reboiler-condenser in the bottom of low pressure respectively top of high pressure 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
    • F25J2210/00—Processes characterised by the type or other details of the feed stream
    • F25J2210/42—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
    • F25J2210/00—Processes characterised by the type or other details of the feed stream
    • F25J2210/50—Oxygen
    • 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
    • F25J2215/00—Processes characterised by the type or other details of the product stream
    • F25J2215/50—Oxygen or special cases, e.g. isotope-mixtures or low purity O2
    • 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
    • F25J2245/00—Processes or apparatus involving steps for recycling of process streams
    • F25J2245/40—Processes or apparatus involving steps for recycling of process streams the recycled stream being air
    • 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
    • F25J2250/00—Details related to the use of reboiler-condensers
    • F25J2250/30—External or auxiliary boiler-condenser in general, e.g. without a specified fluid or one fluid is not a primary air component or an intermediate fluid
    • F25J2250/40—One fluid being air
    • 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
    • F25J2250/00—Details related to the use of reboiler-condensers
    • F25J2250/30—External or auxiliary boiler-condenser in general, e.g. without a specified fluid or one fluid is not a primary air component or an intermediate fluid
    • F25J2250/50—One fluid being oxygen
    • 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
    • F25J2290/00—Other details not covered by groups F25J2200/00 - F25J2280/00
    • F25J2290/12—Particular process parameters like pressure, temperature, ratios

Definitions

  • the present invention relates to an apparatus and to a process for the separation of air by cryogenic distillation.
  • an air separation apparatus comprising a double column with a first column operating at a first pressure and a second column operating at a second pressure, lower than the first pressure.
  • the top of the first column produces a gas which condenses in a reboiler of the second column.
  • the purification of air is generally carried out at a pressure equal to or greater than that of the first pressure. This makes it possible to reduce the volume of the purification unit.
  • JPH11063810 and EP 1 050 730 are similar to U.S. Pat. No. 5,934,105.
  • the air flow going to the first column is approximately 66% of the total purified flow, for example in order to produce 96% oxygen. This means that it is necessary to pass 34% of the air flow at a relatively low pressure through the turbine.
  • the turbine according to the prior art is at least 4 to 5 times larger due to the volume flow rate.
  • the regulation of the refrigerating capacity cannot be done by a reduction in the turbine flow and thus will be done by adjusting the pressure upstream of the turbine, that is to say the purification pressure and ultimately the pressure of the blower. This enormously complicates the regulation and makes it necessary to proportion the purification to the lowest pressure which might be had with a refrigerating capacity lower than nominally expected or in a transient phase.
  • the invention provides a process which consumes 1% less energy (2% less if a turbine efficiency reduced by 5% pt is considered) compared to the prior art (for example, according to EP 1 050 730); according to the process of EP 1 050 730, the purification is carried out at a pressure between the first and the second pressure.
  • the expansion ratio of the process of EP 1 050 730 is low, between 1.2:1 and 3.8:1, preferably between 1.4:1 and 2.5:1, while conventional cryogenic turbines are in an expansion ratio range of between 4:1 and 10:1.
  • the invention uses an expansion ratio which remains at the low limit of this range, thus avoiding having a significantly degraded turbine efficiency.
  • the inlet pressure of the purification unit is typically 2.5 bara (instead of approximately 1.3 bara according to certain embodiments of the invention).
  • This process uses a first compressor having several, typically two, stages with cooling between two stages.
  • the compressor which compresses all the air has a single stage and thus no cooling between two stages.
  • the apparatus produces a gas flow enriched in oxygen with a particularly low energy.
  • U.S. Pat. No. 5,666,824 describes a process according to the preamble of claim 1 but in which the first flow is at least partially condensed in an intermediate condenser of the second column. While a gas is formed, it is itself condensed in another intermediate condenser of the second column and the liquid thus formed is sent to the top of the second column. Thus the first flow is not sent directly to the distillation.
  • WO2013/014252 describes, in FIG. 6, a process in which a first part of the air is cooled to its dew point in a heat exchanger where a flow of air expanded in a turbine is also cooled to its dew point. This is impossible since the waste nitrogen which cools the air flows has already been reheated in a subcooler. In this case, the nitrogen is too hot to cool the air flows to their dew point and the air flows will be cooled at the very most to a temperature approximately 10° C. above the dew point.
  • an air separation apparatus comprising a double column with a first column operating at a first pressure and a second column operating at a second pressure, lower than the first pressure, the second column having a bottom reboiler, means for sending nitrogen-enriched gas from the top of the first column to the bottom reboiler and means for sending at least a part of the condensed nitrogen-enriched gas from the bottom reboiler to the top of the first column, a heat exchanger, a purification unit, means for sending air to the purification unit at a third pressure greater than atmospheric pressure by at most 1 bar, a pipe for sending a first flow of air purified in the purification unit to the heat exchanger at a fourth pressure greater than the second pressure by at most 1 bar, a pipe for introducing the first flow of purified air cooled in the heat exchanger into the second column in order to be separated therein, a booster, a pipe for sending a second flow of air purified in the purification unit to the booster
  • the FIGURE shows an embodiment of the invention.
  • FIG. 1 represents a process for the separation of air by cryogenic distillation according to certain embodiments of the invention.
  • An apparatus for the separation of air by cryogenic distillation comprises a double column with a first column K 3 operating at a first pressure and a second column K 4 operating at a second pressure, lower than the first pressure, the second column having a bottom reboiler M.
  • the second column K 4 does not contain an intermediate condenser.
  • the first pressure is 4.5 bara and the second pressure is 1.13 bara.
  • a nitrogen-enriched gas is sent from the top of the first column to the bottom reboiler M and at least a part of the condensed nitrogen-enriched gas from the bottom reboiler is sent to the top of the first column.
  • Air at atmospheric pressure is filtered in a filter A, compressed by a blower B having a single stage at a pressure at most 1 bar, preferably at most 0.5 bar, above atmospheric pressure, cooled by a cooling means C and purified of water and carbon dioxide in a single purification unit D in which the air 4 enters at a third pressure greater than atmospheric pressure by at most 1 bar, preferably by at most 0.5 bar.
  • the purification unit comprises two adsorbent beds used alternately to purify the air, one bed purifying the air while the other is regenerated.
  • the air purified in the unit D is divided into two in order to form two flows 6 , 8 .
  • the air 8 is neither compressed nor expanded and is at a pressure which differs from the second pressure by a pressure equal to the pressure drops in the pipes and the heat exchanger G.
  • the first flow 8 represents between 20 vol % and 30 vol % of the flow 4 and the second flow 6 represents between 70 vol % and 80 vol % of the flow 4 .
  • the air 8 is sent directly from the purification unit to the second column K 2 to be separated therein, entering the column in entirely gaseous form.
  • the air 8 is cooled in the heat exchanger G down to a temperature at least 5° C. above its dew point.
  • the flow 6 is boosted in a booster E, cooled in a cooler F and sent to the heat exchanger G.
  • the booster E boosts the air 6 up to a fifth pressure between the first pressure and 1 bar above the first pressure.
  • the air 6 is divided into two parts 30 , 32 at an intermediate level of the exchanger.
  • the air 30 leaves the exchanger at an intermediate temperature of the latter, for example ⁇ 125° C., is expanded in a turbine 28 down to the second pressure and enters in gaseous form, mixed with the flow 8 , to be separated in the second column K 4 .
  • the flow 30 can represent between 6 vol % and 15 vol %, preferably between 6% and 8%, of the air 4 .
  • the air 32 is cooled down to the cold end of the exchanger G and is sent to the bottom of the first column K 3 in essentially gaseous form in order to be separated therein.
  • the air 8 is cooled in the heat exchanger G down to a temperature at least 5° C. above its dew point.
  • An oxygen-enriched liquid flow 34 is withdrawn at the bottom of the first column and sent to a level of the second column which is above the air inlet.
  • the air can enter the second column at the same level as that of the arrival of the liquid 34 .
  • the expanded liquid 34 can be separated in a phase separator: the liquid resulting from the phase separator is sent to the column K 4 and the vapor phase can be mixed at the inlet of air 8 , 30 into the column K 4 .
  • a flow of liquid nitrogen 35 is withdrawn from the top of the first column and sent to the top of the second column.
  • Gaseous nitrogen 36 is withdrawn at the top of the second column K 4 and is heated in the subcooler S and subsequently in the exchanger G. A part 14 of this gas is used to regenerate the purification unit D.
  • Gaseous oxygen 29 is withdrawn at the bottom of the second column K 4 .
  • the flow 29 preferably contains at least 80 mol % oxygen, indeed even at least 90 mol % oxygen, but preferably less than 98 mol % oxygen.
  • the process does not produce any liquid flow as final product.
  • the process does not produce any liquid flow to be vaporized in order to form a final gaseous product, optionally under pressure. It is, however, possible to produce a small amount of final gaseous product in this way, which can optionally be mixed with the main gaseous product.
  • the air 8 and/or the air 30 can be subcooled in the sub cooler S and then be introduced into the second column K 4 . Otherwise, the mixture of the flows 8 and 30 can be subcooled in the subcooler S and then be introduced into the second column K 4 .
  • the flow 29 is a flow of gaseous oxygen which is heated in the heat exchanger G from the cold end of the exchanger G.
  • the flow 29 can be a flow of oxygen-rich liquid pressurized to a pressure above that of the second column K 4 .
  • the liquid 29 is vaporized either in a dedicated vaporizer (not illustrated) or in the heat exchanger G.
  • the liquid 29 can be vaporized by heat exchange with all the air 32 in order to partially condense the air 32 , which will subsequently be sent to the bottom of the first column K 3 . Otherwise the liquid 29 can be vaporized by heat exchange with a part of the air 32 in order to completely condense this part of the air 32 .
  • the condensed air will subsequently be sent to the bottom of the first column K 3 or to an intermediate point of the first and/or of the second column.
  • a part of the purified air can be boosted in a booster to a pressure greater than that of the first column K 3 in order to vaporize the liquid 29 .
  • “Comprising” in a claim is an open transitional term which means the subsequently identified claim elements are a nonexclusive listing (i.e., anything else may be additionally included and remain within the scope of “comprising”). “Comprising” as used herein may be replaced by the more limited transitional terms “consisting essentially of” and “consisting of” unless otherwise indicated herein.
  • Providing in a claim is defined to mean furnishing, supplying, making available, or preparing something. The step may be performed by any actor in the absence of express language in the claim to the contrary.
  • Optional or optionally means that the subsequently described event or circumstances may or may not occur.
  • the description includes instances where the event or circumstance occurs and instances where it does not occur.
  • Ranges may be expressed herein as from about one particular value, and/or to about another particular value. When such a range is expressed, it is to be understood that another embodiment is from the one particular value and/or to the other particular value, along with all combinations within said range.

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  • General Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • Emergency Medicine (AREA)
  • Separation By Low-Temperature Treatments (AREA)
  • Oxygen, Ozone, And Oxides In General (AREA)
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FR1873736A FR3090831B1 (fr) 2018-12-21 2018-12-21 Appareil et procédé de séparation d’air par distillation cryogénique
FR1873736 2018-12-21
PCT/FR2019/052934 WO2020128205A1 (fr) 2018-12-21 2019-12-05 Appareil et procédé de séparation d'air par distillation cryogénique

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FR3119884B1 (fr) 2021-02-18 2022-12-30 Air Liquide Procédé de séparation d’air par distillation cryogénique
FR3128776A3 (fr) 2021-10-28 2023-05-05 L'air Liquide Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude Procédé et appareil de séparation d’air par distillation cryogénique

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FR3090831B1 (fr) 2022-06-03
EP3899389A1 (fr) 2021-10-27
AU2019408677A1 (en) 2021-07-15
JP2022514746A (ja) 2022-02-15
CA3122855A1 (en) 2020-06-25
WO2020128205A1 (fr) 2020-06-25
BR112021011589A2 (pt) 2021-08-31
CN113242952A (zh) 2021-08-10
FR3090831A1 (fr) 2020-06-26
JP7451532B2 (ja) 2024-03-18

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