FR2915271A1 - Air separating method, involves operating extracted nitrogen gas from high pressure column at pressure higher than pressure of systems operating at low pressure, and compressing gas till pressure is higher than high pressure of systems - Google Patents
Air separating method, involves operating extracted nitrogen gas from high pressure column at pressure higher than pressure of systems operating at low pressure, and compressing gas till pressure is higher than high pressure of systems Download PDFInfo
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- FR2915271A1 FR2915271A1 FR0754631A FR0754631A FR2915271A1 FR 2915271 A1 FR2915271 A1 FR 2915271A1 FR 0754631 A FR0754631 A FR 0754631A FR 0754631 A FR0754631 A FR 0754631A FR 2915271 A1 FR2915271 A1 FR 2915271A1
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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
- F25J3/04763—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
- F25J3/04812—Different modes, i.e. "runs" of operation
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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
- F25J3/04048—Providing pressurised feed air or process streams within or from the air fractionation unit by compression of cold gaseous streams, e.g. intermediate or oxygen enriched (waste) streams
- F25J3/0406—Providing pressurised feed air or process streams within or from the air fractionation unit by compression of cold gaseous streams, e.g. intermediate or oxygen enriched (waste) streams of nitrogen
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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
- F25J3/04284—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
- F25J3/04296—Claude expansion, i.e. expanded into the main or high pressure column
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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
- F25J3/04284—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
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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
- F25J3/04284—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
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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
- F25J3/04375—Details relating to the work expansion, e.g. process parameter etc.
- F25J3/04381—Details relating to the work expansion, e.g. process parameter etc. using work extraction by mechanical coupling of compression and expansion so-called companders
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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
- F25J3/04375—Details relating to the work expansion, e.g. process parameter etc.
- F25J3/04393—Details relating to the work expansion, e.g. process parameter etc. using multiple or multistage gas work expansion
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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
- F25J3/04406—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
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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
- 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
- F25J2215/52—Oxygen production with multiple purity O2
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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)
Abstract
Description
2915271 La présente invention est relative à un procédé et à un appareilThe present invention relates to a method and apparatus
de séparation des gaz de l'air par distillation cryogénique. Il est connu de produire en sortie de boite froide, en même temps que de l'oxygène et/ou de l'argon, de l'azote par distillation cryogénique. separation of air gases by cryogenic distillation. It is known to produce at the outlet of the cold box, at the same time as oxygen and / or argon, nitrogen by cryogenic distillation.
Cet azote est dans l'état de l'art soit sorti directement sous forme gazeuse d'une des colonnes du système, soit pompé et vaporisé dans la ligne d'échange. Il est un but de l'invention de prévoir un procédé permettant de produire de l'azote à une pression supérieure à celle de la colonne à la pression la plus io élevée du système, sans vaporisation d'azote dans l'échangeur. Selon l'invention, une température cryogénique est une température en dessous de ù 20 C et préférentiellement moins de -100 C et une turbine cryogénique est alimentée par un fluide à moins de -20 C et préférentiellement moins de -100 C. This nitrogen is in the state of the art either directly in gaseous form from one of the columns of the system, or pumped and vaporized in the exchange line. It is an object of the invention to provide a process for producing nitrogen at a pressure higher than that of the column at the highest pressure of the system, without vaporization of nitrogen in the exchanger. According to the invention, a cryogenic temperature is a temperature below 20 ° C. and preferably less than -100 ° C. and a cryogenic turbine is fed with a fluid at less than -20 ° C. and preferentially less than -100 ° C.
15 Selon un objet de l'invention, il est prévu un procédé de séparation d'air dans lequel de l'air comprimé, épuré et refroidi dans une ligne d'échange est séparé dans un système de colonnes par distillation cryogénique, dans lequel on soutire un débit d'azote gazeux d'une colonne du système et on le comprime dans un compresseur entraîné par une turbine cryogénique, éventuellement 20 après avoir été réchauffé dans la ligne d'échange, caractérisé en ce que la colonne d'où est soutiré l'azote opère à une pression plus élevée que celle de la colonne du système opérant à la plus basse pression et l'azote comprimé est comprimé jusqu'à une pression supérieure à la pression la plus élevée des colonnes du système.According to an object of the invention, there is provided an air separation process in which compressed, purified and cooled air in a heat exchange line is separated in a column system by cryogenic distillation, wherein withdrawing a nitrogen gas flow from a column of the system and compressing it in a compressor driven by a cryogenic turbine, possibly after being heated in the exchange line, characterized in that the column from which is drawn off the nitrogen operates at a higher pressure than that of the lower pressure system column and the compressed nitrogen is compressed to a pressure higher than the highest pressure of the columns of the system.
25 Selon d'autres aspects facultatifs : - l'aspiration du compresseur d'azote se fait à une température cryogénique ; - la turbine cryogénique est une turbine d'insufflation d'air ; - la turbine cryogénique est une turbine de détente d'azote ; 30 - la turbine et le compresseur d'azote forment une seule machine équipée d'un frein d'huile permettant d'assurer au moins partiellement la tenue en froid du procédé ; - la turbine et le compresseur forment une seule machine et la turbine entraîne également un compresseur d'air ; 2 2915271 - l'air envoyé au système de colonnes comprend au moins un débit comprimé dans un deuxième compresseur, refroidi, détendu dans une deuxième turbine et envoyé à une colonne du système ; - l'azote est comprimé à une pression comprise entre 1, 2 et 3 fois la 5 pression de la colonne dont il est soutiré ; - le système de colonnes comprend une double colonne, dont une colonne moyenne pression et une colonne basse pression reliées thermiquement l'une avec l'autre et dans lequel on soutire l'azote gazeux de la colonne moyenne pression ; le compresseur entraîné par la turbine cryogénique comprime l'azote à entre 10 et 15 bars ; - on soutire un débit d'oxygène gazeux du système de colonnes et dans lequel le débit d'azote comprimé dans le compresseur représente un pourcentage du débit d'oxygène gazeux inférieur à 50%, voire inférieure à 25%; - l'azote comprimé dans le compresseur est envoyé ensuite à la ligne d'échange où il se réchauffe ; - dans une première marche on opère comme décrit ci-dessus et on soutire un débit d'oxygène à une première pureté de la colonne basse pression et dans une deuxième marche on réduit, éventuellement jusqu'à zéro, le débit d'azote envoyé vers le compresseur et on soutire un débit d'oxygène à une deuxième pureté, plus élevée que la première pureté, de la colonne basse pression Selon un autre aspect de l'invention, il est prévu un appareil de séparation d'air par distillation cryogénique comprenant : i) une ligne d'échange ii) un système de colonnes iii) un premier compresseur iv) une première turbine couplée au premier compresseur v) des moyens pour envoyer un débit d'air comprimé et épuré à la ligne d'échange pour le refroidir et ensuite au système de colonnes vi) des moyens pour soutirer un débit riche en azote d'une colonne du système de colonnes autre que la colonne opérant à la pression la plus basse et des moyens pour l'envoyer au premier compresseur 3 2915271 vii) des moyens pour envoyer un gaz de la ligne d'échange à la première turbine. Eventuellement l'appareil ne comprend aucun moyen de réchauffage entre le point de soutirage du débit riche en azote et le premier compresseur.According to other optional aspects: the suction of the nitrogen compressor is at a cryogenic temperature; the cryogenic turbine is an air blower turbine; the cryogenic turbine is a nitrogen expansion turbine; - The turbine and the nitrogen compressor form a single machine equipped with an oil brake to ensure at least partially cold resistance of the process; the turbine and the compressor form a single machine and the turbine also drives an air compressor; 2 2915271 - the air sent to the column system comprises at least one compressed flow rate in a second compressor, cooled, expanded in a second turbine and sent to a column of the system; the nitrogen is compressed at a pressure of between 1, 2 and 3 times the pressure of the column from which it is withdrawn; - The column system comprises a double column, including a medium pressure column and a low pressure column thermally connected to one another and wherein the nitrogen gas is withdrawn from the medium pressure column; the compressor driven by the cryogenic turbine compresses nitrogen to between 10 and 15 bar; a flow of gaseous oxygen is withdrawn from the column system and in which the compressed nitrogen flow rate in the compressor represents a percentage of the oxygen gas flow rate of less than 50%, or even less than 25%; compressed nitrogen in the compressor is then sent to the exchange line where it heats up; in a first step, the procedure is as described above and a flow of oxygen at a first purity of the low pressure column is withdrawn and in a second step the flow of nitrogen sent to the compressor and withdraws an oxygen flow rate at a second purity, higher than the first purity, of the low pressure column. According to another aspect of the invention, there is provided a cryogenic distillation air separation apparatus comprising i) an exchange line ii) a column system iii) a first compressor iv) a first turbine coupled to the first compressor v) means for sending a flow of compressed and purified air to the exchange line for the and then to the column system vi) means for withdrawing a nitrogen-rich flow of a column from the column system other than the column operating at the lowest pressure and means for sending it to the first column. presser 3 2915271 vii) means for sending a gas from the exchange line to the first turbine. Optionally the apparatus does not include any heating means between the nitrogen-rich flow-off point and the first compressor.
5 Le système de colonnes peut comprendre au moins une double colonne, comprenant une colonne moyenne pression et une colonne basse pression reliées thermiquement entre elles et dans lequel les moyens pour soutirer le débit riche en azote sont reliés à la colonne moyenne pression. L'appareil peut comprendre des moyens pour envoyer le débit du io premier compresseur à la ligne d'échange. Un avantage du procédé par rapport à l'art antérieur est que l'on peut produire de l'azote à une pression comprise entre 5 et 15 bar sans avoir recours à un compresseur alimenté par un moteur électrique. Optionnellement le compresseur d'azote n'est pas couplé à un moteur 15 électrique. Dans le cas il y a un surpresseur d'air, avantageusement celui-ci n'est pas couplé à moteur électrique non plus. C'est particulièrement intéressant quand on dispose d'un excès d'air à 5 bar que l'on peut utiliser dans une ou des turbines cryogéniques. Par rapport à un schéma selon l'art antérieur où on sortirait l'azote de la 20 colonne moyenne pression à 5 bar puis on le comprimerait à 10-15 bar, la consommation d'énergie du procédé selon l'invention est plus faible si on se situe dans le cas d'un appareil dont le rapport des débits d'azote moyenne pression et oxygène gazeux basse pression est bas (typiquement inférieur à 50 % pour un appareil produisant de l'oxygène impur, voire inférieur à 25 pour 25 un appareil produisant de l'oxygène pur). L'oxygène peut être produit gazeux à pression atmosphérique ou à pompe. L'invention sera décrite en plus de détail en se référant aux figures qui montre un procédé de séparation d'air selon l'invention.The column system may comprise at least one double column, comprising a medium pressure column and a low pressure column thermally connected to each other and wherein the means for withdrawing the nitrogen rich flow are connected to the medium pressure column. The apparatus may include means for sending the flow rate of the first compressor to the exchange line. One advantage of the process over the prior art is that nitrogen can be produced at a pressure of between 5 and 15 bar without the use of a compressor powered by an electric motor. Optionally, the nitrogen compressor is not coupled to an electric motor. In the case there is an air booster, advantageously it is not coupled to electric motor either. This is particularly interesting when there is an excess of air at 5 bar that can be used in one or more cryogenic turbines. With respect to a scheme according to the prior art in which the nitrogen from the medium pressure column would be discharged at 5 bar and then compressed to 10-15 bar, the energy consumption of the process according to the invention is lower if it is in the case of an apparatus whose ratio of low pressure nitrogen and low pressure oxygen gas flow rates is low (typically less than 50% for an apparatus producing impure oxygen, or even less than 25 for an apparatus apparatus producing pure oxygen). Oxygen can be gaseous product at atmospheric pressure or pump. The invention will be described in more detail with reference to the figures which shows an air separation method according to the invention.
30 Dans les deux figures, l'appareil de séparation comprend une ligne d'échange 17, une double colonne avec une colonne moyenne pression 31 reliée thermiquement à une colonne basse pression 33 à travers un rebouilleur-condenseur.In both figures, the separation apparatus comprises an exchange line 17, a double column with a medium pressure column 31 thermally connected to a low pressure column 33 through a reboiler-condenser.
4 2915271 Selon la Figure 1, de l'air comprimé et épuré 1 est divisé en deux. Une partie 3 est refroidi dans la ligne d'échange 17 puis divisée en deux. Une fraction 23 poursuit son refroidissement jusqu'au bout froid de la ligne d'échange puis est envoyé sous forme gazeuse à la colonne moyenne pression 5 31. Le reste 21 est détendu dans une turbine d'insufflation 27 et envoyé après refroidissement dans le sous-refroidisseur 41 à la colonne basse pression 33 à un niveau intermédiaire. La température d'entrée de la turbine 27 est inférieure à û -20 C, de préférence inférieure à -100 C. io Une autre partie de l'air 5 est comprimée dans un compresseur 7, refroidie par un refroidisseur 11, refroidie de nouveau dans la ligne d'échange 17 puis détendue entièrement à une température intermédiaire de la ligne d'échange dans une turbine 13 qui entraîne le compresseur 7. L'air détendu 5 se mélange avec le débit 21 pour former un débit 25 qui est envoyé à la 15 colonne basse pression 33. Un débit de liquide riche 39 et un débit de liquide pauvre 37 sont envoyés à la colonne basse pression 33, le liquide riche étant envoyé au même niveau que l'air 25. Un débit d'azote basse pression 35 est soutiré de la tête de la colonne basse pression, se réchauffe dans le sous-refroidisseur 41 et puis se réchauffe 20 jusqu'au bout chaud de la ligne d'échange 17. Un débit d'oxygène basse pression 9 est soutiré de la cuve de la colonne basse pression 33 sous forme gazeuse et se réchauffe jusqu'au bout chaud de la ligne d'échange 17. Un débit d'azote moyenne pression 19 est soutiré de la tête de la 25 colonne moyenne pression 31, comprimé dans le compresseur 15 sans avoir été réchauffé, envoyé à un niveau intermédiaire de la ligne d'échange 17 puis réchauffé jusqu'au bout chaud de la ligne d'échange. La température d'entrée du compresseur 15 est inférieure à -20 C, de préférence inférieure à -100 C.La température d'entrée du compresseur 15 est 30 inférieure à la température d'entrée de la turbine 27 et la température de sortie du compresseur 15 est supérieure à la température d'entrée de la turbine 27. L'appareil comprend dans ce cas deux machines, chacune comprenant un compresseur couplé à une turbine. Une des machines est constituée par le compresseur d'air 7 couplé à la turbine 13 qui détend le même débit d'air.According to FIG. 1, compressed and purified air 1 is divided in two. Part 3 is cooled in the exchange line 17 and then divided into two. A fraction 23 continues cooling to the cold end of the exchange line and is then sent in gaseous form to the medium pressure column 31. The remainder 21 is expanded in an insufflation turbine 27 and sent after cooling in the sub -cooler 41 to the low pressure column 33 at an intermediate level. The inlet temperature of the turbine 27 is less than -20 ° C, preferably less than -100 ° C. Another part of the air 5 is compressed in a compressor 7, cooled by a cooler 11, cooled again in the exchange line 17 and then fully expanded to an intermediate temperature of the exchange line in a turbine 13 which drives the compressor 7. The expanded air 5 mixes with the flow 21 to form a flow 25 which is sent to the low pressure column 33. A rich liquid flow 39 and a low liquid flow 37 are sent to the low pressure column 33, the rich liquid being sent at the same level as the air 25. A low pressure nitrogen flow 35 is withdrawn from the head of the low pressure column, warms up in the subcooler 41 and then heats up to the hot end of the exchange line 17. A low pressure oxygen flow 9 is withdrawn from the low pressure column vessel 33 in gaseous form and warms up to the hot end of the exchange line 17. A medium pressure nitrogen flow 19 is withdrawn from the head of the medium pressure column 31, compressed in the compressor 15 without being heated, sent to an intermediate level of the exchange line 17 and then warmed to the hot end of the exchange line. The inlet temperature of the compressor 15 is less than -20 ° C., preferably less than -100 ° C. The inlet temperature of the compressor 15 is lower than the inlet temperature of the turbine 27 and the outlet temperature of the compressor 15 is greater than the inlet temperature of the turbine 27. The apparatus comprises in this case two machines, each comprising a compressor coupled to a turbine. One of the machines is constituted by the air compressor 7 coupled to the turbine 13 which relaxes the same air flow.
5 2915271 L'autre machine est constituée par un compresseur froid d'azote 15 couplé à la turbine d'air 27. Au moins une des deux machines ne comprend pas de moteur électrique. L'azote peut éventuellement être réchauffé en amont du compresseur 5 froid. Au moins une des turbines 13, 27 peut être remplacée par une turbine Claude. L'appareil peut également produire de l'argon et/ou au moins un produit liquide. io En fonctionnement normal l'appareil produit de l'oxygène impur (95 mol. % d'oxygène) et peut produire dans une marche de secours de l'oxygène pur (99.5 mol. % d'oxygène) en réduisant fortement (ou en arrêtant) le soutirage d'azote. Selon la Figure 2, de l'air comprimé et épuré 1 est divisé en deux. Une 15 partie 3 est refroidi dans la ligne d'échange 17 puis est envoyé à la colonne moyenne pression 31. L'autre partie de l'air 5 est comprimée dans un compresseur 7, refroidie par un refroidisseur 11, refroidie de nouveau dans la ligne d'échange 17 puis détendue entièrement à une température intermédiaire de la ligne d'échange 20 dans une turbine 13 qui entraîne le compresseur 7. L'air détendu 5 est envoyé à la colonne basse pression 33. Un débit de liquide riche 39 et un débit de liquide pauvre 37 sont envoyés à la colonne basse pression 33, le liquide riche étant envoyé au même niveau que l'air 25. Un débit d'azote basse pression 35 est soutiré de la tête de la colonne 25 basse pression, se réchauffe dans le sous-refroidisseur 41 et puis se réchauffe jusqu'au bout chaud de la ligne d'échange 17. Un débit d'oxygène basse pression 9 est soutiré de la cuve de la colonne basse pression 33 sous forme gazeuse et se réchauffe jusqu'au bout chaud de la ligne d'échange 17.The other machine is constituted by a cold nitrogen compressor 15 coupled to the air turbine 27. At least one of the two machines does not include an electric motor. The nitrogen may optionally be reheated upstream of the cold compressor. At least one of the turbines 13, 27 can be replaced by a turbine Claude. The apparatus may also produce argon and / or at least one liquid product. In normal operation the apparatus produces impure oxygen (95 mol% oxygen) and can produce pure oxygen (99.5 mol% oxygen) in a backup step by greatly reducing (or stopping) the nitrogen withdrawal. According to Figure 2, compressed and purified air 1 is divided in two. One part 3 is cooled in the exchange line 17 and then sent to the medium pressure column 31. The other part of the air 5 is compressed in a compressor 7, cooled by a cooler 11, cooled again in the exchange line 17 then fully expanded to an intermediate temperature of the exchange line 20 in a turbine 13 which drives the compressor 7. The expanded air 5 is sent to the low pressure column 33. A rich liquid flow 39 and a low liquid flow rate 37 is sent to the low pressure column 33, the rich liquid being sent at the same level as the air 25. A low pressure nitrogen flow 35 is withdrawn from the head of the low pressure column, heats up in the subcooler 41 and then heats up to the hot end of the exchange line 17. A low pressure oxygen flow 9 is withdrawn from the tank of the low pressure column 33 in gaseous form and heats up to at the hot end of the lign e of exchange 17.
30 Un débit d'azote moyenne pression 19 est soutiré de la tête de la colonne moyenne pression 31, réchauffé dans la ligne d'échange 17 et puis divisé en deux. Une partie 45 est comprimé dans le compresseur 15, envoyé à un niveau intermédiaire de la ligne d'échange 17 puis réchauffé jusqu'au bout chaud de la ligne d'échange.A medium pressure nitrogen flow 19 is withdrawn from the head of the medium pressure column 31, reheated in the exchange line 17 and then divided in two. A portion 45 is compressed in the compressor 15, sent to an intermediate level of the exchange line 17 and then warmed to the hot end of the exchange line.
6 2915271 La température d'entrée du compresseur 15 est inférieure à -20 C, de préférence inférieure à -100 C. Le reste de l'azote moyenne pression 43 est détendu dans une turbine 27A et renvoyé à la ligne d'échange où il se réchauffe à la température du bout 5 chaud après s'être mélangé à l'azote basse pression 35 pour former un débit 47. La température d'entrée de la turbine 27A est inférieure à ù -20 C, de préférence inférieure à -100 C. La température d'entrée du compresseur 15 est égale à la température d'entrée de la turbine 27A et la température de sortie du compresseur 15 est io supérieure à la température d'entrée de la turbine 27A. L'appareil comprend dans ce cas également deux machines, chacune comprenant un compresseur couplé à une turbine. Une machine est constituée par le compresseur d'air 7 couplé à la turbine 13 qui détend le même débit d'air. L'autre machine est constituée du compresseur froid d'azote 15 couplé à la 15 turbine d'azote 27A. Au moins une des deux machines ne comprend pas de moteur électrique. Au moins une des turbines 13, 27, 27A peut être remplacée par une turbine Claude. L'appareil peut également produire de l'argon et/ou au moins un produit 20 liquide. En fonctionnement normal l'appareil produit de l'oxygène impur (95 mol. % d'oxygène) et peut produire dans une marche de secours de l'oxygène pur (99.5 mol. % d'oxygène) en réduisant fortement (ou en arrêtant) le soutirage d'azote.The inlet temperature of the compressor 15 is less than -20 ° C., preferably less than -100 ° C. The remainder of the medium pressure nitrogen 43 is expanded in a turbine 27A and returned to the exchange line where it is heated to hot end temperature after mixing with the low pressure nitrogen to form a flow rate 47. The inlet temperature of the turbine 27A is less than -20 C, preferably less than -100 C. The inlet temperature of the compressor 15 is equal to the inlet temperature of the turbine 27A and the outlet temperature of the compressor 15 is greater than the inlet temperature of the turbine 27A. The apparatus also comprises in this case also two machines, each comprising a compressor coupled to a turbine. A machine is constituted by the air compressor 7 coupled to the turbine 13 which relaxes the same air flow. The other machine is the cold nitrogen compressor 15 coupled to the nitrogen turbine 27A. At least one of the two machines does not include an electric motor. At least one of the turbines 13, 27, 27A may be replaced by a turbine Claude. The apparatus may also produce argon and / or at least one liquid product. In normal operation the apparatus produces impure oxygen (95 mol% oxygen) and can produce pure oxygen (99.5 mol% oxygen) in a backup step by strongly reducing (or stopping ) the nitrogen withdrawal.
25 Dans tous les cas, la double colonne peut être remplacée par une triple colonne, l'azote destiné au compresseur étant soutiré de la colonne haute pression ou la colonne à pression intermédiaire. 15 30 7In all cases, the double column can be replaced by a triple column, the nitrogen for the compressor being withdrawn from the high pressure column or the intermediate pressure column. 15 30 7
Claims (17)
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FR0754631A FR2915271A1 (en) | 2007-04-23 | 2007-04-23 | Air separating method, involves operating extracted nitrogen gas from high pressure column at pressure higher than pressure of systems operating at low pressure, and compressing gas till pressure is higher than high pressure of systems |
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FR0754631A FR2915271A1 (en) | 2007-04-23 | 2007-04-23 | Air separating method, involves operating extracted nitrogen gas from high pressure column at pressure higher than pressure of systems operating at low pressure, and compressing gas till pressure is higher than high pressure of systems |
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FR0754631A Withdrawn FR2915271A1 (en) | 2007-04-23 | 2007-04-23 | Air separating method, involves operating extracted nitrogen gas from high pressure column at pressure higher than pressure of systems operating at low pressure, and compressing gas till pressure is higher than high pressure of systems |
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CN109387031A (en) * | 2017-08-03 | 2019-02-26 | 乔治洛德方法研究和开发液化空气有限公司 | Device and method for separating air by low temperature distillation |
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