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JP2013011374A - Air separation method and device - Google Patents

Air separation method and device Download PDF

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JP2013011374A
JP2013011374A JP2011143159A JP2011143159A JP2013011374A JP 2013011374 A JP2013011374 A JP 2013011374A JP 2011143159 A JP2011143159 A JP 2011143159A JP 2011143159 A JP2011143159 A JP 2011143159A JP 2013011374 A JP2013011374 A JP 2013011374A
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pressure
oxygen
low
air
liquefied
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JP5878310B2 (en
JP2013011374A5 (en
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Hiroshi Tachibana
博志 橘
Takashi Tatsumi
高司 辰巳
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Nippon Sanso Holdings Corp
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Nippon Sanso Holdings Corp
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Priority to JP2011143159A priority Critical patent/JP5878310B2/en
Priority to PCT/JP2012/065071 priority patent/WO2013002025A1/en
Priority to EP12803534.2A priority patent/EP2728286A4/en
Priority to CN201280032710.1A priority patent/CN103620330B/en
Priority to US14/127,252 priority patent/US20140109614A1/en
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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
    • 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
    • F25J3/04436—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 at least a triple pressure main column system
    • F25J3/04448—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 at least a triple pressure main column system in a double column flowsheet with an intermediate 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
    • F25J3/04624—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 integrated mass and heat exchange, so-called non-adiabatic rectification, e.g. dephlegmator, reflux exchanger
    • F25J3/0463—Simultaneously between rectifying and stripping sections, i.e. double dephlegmator
    • 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
    • F25J2200/08—Processes or apparatus using separation by rectification in a triple pressure main column system
    • 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
    • F25J2200/52—Processes or apparatus using separation by rectification using multiple (re-)boiler-condensers at different heights of the column in the high pressure column of a double pressure main column system
    • 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
    • F25J2200/54—Processes or apparatus using separation by rectification using multiple (re-)boiler-condensers at different heights of the column in the low pressure column of a double pressure main column system

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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

PROBLEM TO BE SOLVED: To provide an air separation method which can reduce power consumption at the sampling of oxygen by a three-tower type process, and a device.SOLUTION: The air separation method includes: a first separation step of separating raw material air into a high-pressure nitrogen gas and high-pressure oxygen-riched liquefied air; a second separation step of separating the high-pressure oxygen-riched liquefied air into a middle-pressure nitrogen gas and middle-pressure oxygen-riched liquefied air; a first indirect heat exchange step of making the low-pressure oxygen-riched liquefied air which is obtained by pressure-reducing the middle-pressure oxygen-riched liquefied air as low-pressure oxygen-riched air, and also making the middle-pressure nitrogen gas as middle-pressure liquefied nitrogen; a third separation step of separating the low-pressure oxygen-riched air into a low-pressure nitrogen gas and low-pressure liquefied oxygen; a second indirect heat exchange step of making the high-pressure nitrogen gas as high-pressure liquefied nitrogen, and also making the low-pressure liquefied oxygen as low-pressure oxygen gas; a third indirect heat exchange step of making the high-pressure nitrogen-riched air in the first separation process as high-pressure nitrogen-riched liquefied air, and also making the middle-pressure oxygen-riched liquefied air as middle-pressure oxygen-riched air; and a product gas recovery step of sampling the low-pressure oxygen gas or the low-pressure liquefied oxygen as a product oxygen gas after heat-recovering it.

Description

本発明は、空気分離方法及び装置に関し、詳しくは、圧縮、精製、冷却した原料空気を低温蒸留することにより、酸素ガスを製品として採取する空気分離方法及び装置に関する。   The present invention relates to an air separation method and apparatus, and more particularly to an air separation method and apparatus for collecting oxygen gas as a product by low-temperature distillation of compressed, purified, and cooled raw material air.

空気を深冷分離して製品酸素ガスを製造する方法としては、従来から複式精留プロセスが最も一般的な方法として知られている。この複式精留プロセスは、圧縮、精製、冷却した原料空気を低温蒸留して高圧窒素ガスと高圧酸素富化液化空気とに分離する高圧塔と、前記高圧酸素富化液化空気を減圧後に低温蒸留して低圧窒素ガスと低圧液化酸素とに分離する低圧塔と、高圧塔頂部の高圧窒素ガスを凝縮液化すると同時に低圧塔底部の低圧液化酸素を蒸発ガス化する主凝縮器とを主な構成機器としている。また、製品酸素ガスに加えて製品窒素ガスを製造する際の消費動力を低減するためのプロセスとして、複式精留プロセスにおける高圧塔の運転圧力と低圧塔の運転圧力との中間の運転圧力で運転する中圧塔を付加した３塔式プロセスが各種提案されている（例えば、特許文献１，２参照。）。   As a method for producing product oxygen gas by cryogenic separation of air, a double rectification process has hitherto been known as the most common method. This double rectification process consists of a high-pressure column that separates compressed, refined, and cooled raw air into low-pressure distilled high-pressure nitrogen gas and high-pressure oxygen-enriched liquefied air, and low-pressure distillation after depressurizing the high-pressure oxygen-enriched liquefied air The main components are a low-pressure column that separates into low-pressure nitrogen gas and low-pressure liquefied oxygen, and a main condenser that condenses and liquefies high-pressure nitrogen gas at the top of the high-pressure column and at the same time evaporates and gasifies low-pressure liquefied oxygen at the bottom of the low-pressure column It is said. In addition, as a process to reduce the power consumed when producing product nitrogen gas in addition to product oxygen gas, operation is performed at an intermediate operating pressure between the high pressure column operating pressure and the low pressure column operating pressure in the double rectification process. Various three-column processes with an intermediate pressure tower added have been proposed (see, for example, Patent Documents 1 and 2).

特開平８−２３３４５７号公報JP-A-8-233457 特開２００１−２６３９３５号公報JP 2001-263935 A

特許文献１に記載されたプロセスでは、低圧塔に供給される流体の酸素濃度が高くなるため、低圧塔の精留条件を改善でき、高圧塔の塔頂から複式精留プロセスに比べて多くの高圧製品窒素ガスを採取できる。また、特許文献２に記載されたプロセスでは、中圧塔の運転圧力を下げることによって中圧塔の塔底から導出される中圧酸素富化液化空気の酸素濃度を特許文献１のプロセスより高くすることができるが、中圧塔の塔頂から製品として採取する中圧窒素ガスの圧力が低くなってしまうため、中圧窒素ガスを圧縮する動力が必要になり、結果的に消費動力の低減は不十分なものとなっていた。   In the process described in Patent Document 1, since the oxygen concentration of the fluid supplied to the low-pressure column becomes high, the rectification conditions of the low-pressure column can be improved, and more than the double rectification process from the top of the high-pressure column. High-pressure product nitrogen gas can be collected. In the process described in Patent Document 2, the oxygen concentration of the medium-pressure oxygen-enriched liquefied air derived from the bottom of the medium-pressure tower is lowered by lowering the operation pressure of the medium-pressure tower than the process of Patent Document 1. However, since the pressure of the medium-pressure nitrogen gas collected as a product from the top of the medium-pressure tower becomes low, power to compress the medium-pressure nitrogen gas is required, resulting in a reduction in power consumption. Was inadequate.

そこで本発明は、３塔式プロセスにおける低圧塔に供給する流体の酸素濃度をより高くすることにより、高圧塔の塔頂や中圧塔の塔頂から導出する窒素ガスの採取量を増やすとともに、消費動力を削減することができる空気分離方法及び装置を提供することを目的としている。   Therefore, the present invention increases the amount of nitrogen gas extracted from the top of the high pressure tower and the top of the intermediate pressure tower by increasing the oxygen concentration of the fluid supplied to the low pressure tower in the three-column process, An object of the present invention is to provide an air separation method and apparatus capable of reducing power consumption.

上記目的を達成するため、本発明の空気分離方法における第１の構成は、原料空気を深冷液化分離して製品酸素を採取する空気分離方法において、圧縮、精製、冷却した原料空気を低温蒸留して高圧窒素ガスと高圧酸素富化液化空気とに分離する第１分離工程と、前記高圧酸素富化液化空気を減圧後に低温蒸留して中圧窒素ガスと中圧酸素富化液化空気とに分離する第２分離工程と、前記中圧酸素富化液化空気を減圧した低圧酸素富化液化空気と前記中圧窒素ガスとを間接熱交換させて中圧窒素ガスを凝縮液化して中圧液化窒素を得ると同時に前記低圧酸素富化液化空気を蒸発ガス化して低圧酸素富化空気を得る第１間接熱交換工程と、前記低圧酸素富化空気を低温蒸留して低圧窒素ガスと低圧液化酸素とに分離する第３分離工程と、前記高圧窒素ガスと前記低圧液化酸素とを間接熱交換させて前記高圧窒素ガスを凝縮液化して高圧液化窒素を得ると同時に前記低圧液化酸素を蒸発ガス化して低圧酸素ガスを得る第２間接熱交換工程と、前記第１分離工程の中間段階で生成した高圧窒素富化空気と前記中圧酸素富化液化空気とを間接熱交換させて前記高圧窒素富化空気を凝縮液化して高圧窒素富化液化空気を得ると同時に前記中圧酸素富化液化空気を蒸発ガス化して中圧酸素富化空気を得る第３間接熱交換工程と、前記低圧酸素ガス又は前記低圧液化酸素を熱回収後に製品酸素ガスとして採取する製品ガス回収工程とを含むことを特徴としている。   In order to achieve the above object, the first configuration of the air separation method of the present invention is a low-temperature distillation of compressed, refined, and cooled raw material air in an air separation method of collecting product oxygen by cryogenic liquefaction separation of raw material air. The high pressure nitrogen gas and the high pressure oxygen enriched liquefied air are separated into a first separation step, and the high pressure oxygen enriched liquefied air is subjected to low-temperature distillation after decompression to obtain medium pressure nitrogen gas and medium pressure oxygen enriched liquefied air. A second separation step for separating, and the low pressure oxygen-enriched liquefied air obtained by reducing the pressure of the intermediate-pressure oxygen-enriched liquefied air and the intermediate-pressure nitrogen gas are indirectly heat exchanged to condense and liquefy the intermediate-pressure nitrogen gas, thereby liquefying the medium-pressure A first indirect heat exchange step for obtaining low-pressure oxygen-enriched air by evaporating and gasifying the low-pressure oxygen-enriched liquefied air simultaneously with obtaining nitrogen; low-pressure nitrogen gas and low-pressure liquefied oxygen by low-temperature distillation of the low-pressure oxygen-enriched air; A third separation step for separating the A second indirect heat exchange step in which nitrogen gas and the low-pressure liquefied oxygen are indirectly heat-exchanged to condense and liquefy the high-pressure nitrogen gas to obtain high-pressure liquefied nitrogen, and at the same time evaporate and gasify the low-pressure liquefied oxygen to obtain low-pressure oxygen gas. And high-pressure nitrogen-enriched liquefied gas by condensing and liquefying the high-pressure nitrogen-enriched air through indirect heat exchange between the high-pressure nitrogen-enriched air generated in the intermediate stage of the first separation step and the intermediate-pressure oxygen-enriched liquefied air A third indirect heat exchange step to obtain air and vaporize the intermediate-pressure oxygen-enriched liquefied air to obtain intermediate-pressure oxygen-enriched air; and product oxygen gas after recovering the low-pressure oxygen gas or the low-pressure liquefied oxygen And a product gas recovery step to be collected as a feature.

また、本発明の空気分離方法における第２の構成は、原料空気を深冷液化分離して製品酸素を採取する空気分離方法において、圧縮、精製、冷却した原料空気を低温蒸留して高圧窒素ガスと高圧酸素富化液化空気とに分離する第１分離工程と、前記高圧酸素富化液化空気を減圧後に低温蒸留して中圧窒素ガスと中圧酸素富化液化空気とに分離する第２分離工程と、前記中圧酸素富化液化空気を減圧した低圧酸素富化液化空気を低温蒸留して低圧窒素ガスと低圧液化酸素とに分離する第３分離工程と、前記中圧窒素ガスと前記第３分離工程の中間段階の低圧酸素富化還流液化空気とを間接熱交換させて中圧窒素ガスを凝縮液化して中圧液化窒素を得ると同時に前記低圧酸素富化還流液化空気を蒸発ガス化して低圧酸素富化蒸発空気を得る第１間接熱交換工程と、前記高圧窒素ガスと前記低圧液化酸素とを間接熱交換させて前記高圧窒素ガスを凝縮液化して高圧液化窒素を得ると同時に前記低圧液化酸素を蒸発ガス化して低圧酸素ガスを得る第２間接熱交換工程と、前記第１分離工程の中間段階の高圧窒素富化空気と前記中圧酸素富化液化空気とを間接熱交換させて前記高圧窒素富化空気を凝縮液化して高圧窒素富化液化空気を得ると同時に前記中圧酸素富化液化空気を蒸発ガス化して中圧酸素富化空気を得る第３間接熱交換工程と、前記低圧酸素ガス又は前記低圧液化酸素を熱回収後に製品酸素ガスとして採取する製品ガス回収工程とを含むことを特徴としている。   The second configuration of the air separation method of the present invention is the air separation method in which the raw material air is subjected to cryogenic liquefaction separation to collect product oxygen. And a second separation for separating the high-pressure oxygen-enriched liquefied air into medium-pressure nitrogen gas and medium-pressure oxygen-enriched liquefied air by performing low-temperature distillation after depressurizing the high-pressure oxygen-enriched liquefied air. A step, a third separation step of low-temperature distillation of the low-pressure oxygen-enriched liquefied air obtained by depressurizing the intermediate-pressure oxygen-enriched liquefied air, and separating it into low-pressure nitrogen gas and low-pressure liquefied oxygen; 3. Indirect heat exchange with the low-pressure oxygen-enriched reflux liquefied air in the intermediate stage of the 3 separation process to condense and liquefy the medium-pressure nitrogen gas to obtain medium-pressure liquefied nitrogen, and at the same time evaporate and gasify the low-pressure oxygen-enriched reflux liquefied air First to obtain low-pressure oxygen-enriched evaporative air Indirect heat exchange between the high-pressure nitrogen gas and the low-pressure liquefied oxygen to condense and liquefy the high-pressure nitrogen gas to obtain high-pressure liquefied nitrogen, and at the same time evaporate and gasify the low-pressure liquefied oxygen and A second indirect heat exchange step to be obtained, and a high-pressure nitrogen-enriched air in the intermediate stage of the first separation step and the intermediate-pressure oxygen-enriched liquefied air are indirectly heat-exchanged to condense and liquefy the high-pressure nitrogen-enriched air. A third indirect heat exchange step for obtaining high-pressure nitrogen-enriched liquefied air and simultaneously evaporating and gasifying the medium-pressure oxygen-enriched liquefied air to obtain medium-pressure oxygen-enriched air; and heating the low-pressure oxygen gas or the low-pressure liquefied oxygen And a product gas recovery step of collecting as product oxygen gas after recovery.

さらに、本発明の空気分離方法において、前記第３間接熱交換工程が、熱交換型蒸留器の一方の通路に前記高圧窒素富化空気を上方向に流しながら凝縮液化して得られた液体を下方向に流す低温蒸留を行うことによって前記高圧窒素富化液化空気に加えてより窒素が濃縮した高圧低純窒素ガスを得ると同時に、前記熱交換型蒸留器の他方の通路に前記中圧酸素富化液化空気を下方向に流しながら蒸発ガス化して得られたガスを上方向に流す低温蒸留を行うことによって前記中圧酸素富化空気に加えてより酸素が濃縮した中圧低純液化酸素を得るように構成することもでき、前記第３間接熱交換工程では、前記高圧窒素富化空気に代えて前記原料空気の一部を使用することもできる。加えて、前記第１分離工程で得られた高圧窒素ガスを熱回収後に採取する高圧窒素ガス回収工程、前記第２分離工程で得られた中圧窒素ガスを熱回収後に採取する中圧窒素ガス回収工程、前記第３分離工程で得られた低圧窒素ガスを熱回収後に採取する低圧窒素ガス回収工程、前記第２間接熱交換工程で凝縮液化した前記高圧液化窒素を採取する高圧液化窒素回収工程、前記第１間接熱交換工程で凝縮液化した前記中圧液化窒素を採取する中圧液化窒素回収工程、及び、前記第３分離工程で得られた前記低圧液化酸素を回収する低圧液化酸素回収工程のうち少なくとも１つの工程を行うことができる。   Furthermore, in the air separation method of the present invention, the third indirect heat exchanging step is a step in which a liquid obtained by condensing and liquefying the high-pressure nitrogen-enriched air while flowing upward in one passage of the heat exchange type distiller is used. In addition to the high-pressure nitrogen-enriched liquefied air, high-pressure low-pure nitrogen gas enriched with nitrogen is obtained by performing low-temperature distillation flowing downward, and at the same time, the medium-pressure oxygen is supplied to the other passage of the heat-exchange distiller Medium-pressure low-pure liquefied oxygen in which oxygen is concentrated in addition to the above-mentioned medium-pressure oxygen-enriched air by performing low-temperature distillation in which the gas obtained by evaporating gas is flowed upward while flowing enriched liquefied air downward In the third indirect heat exchange step, part of the raw material air can be used instead of the high-pressure nitrogen-enriched air. In addition, a high-pressure nitrogen gas recovery step for collecting high-pressure nitrogen gas obtained in the first separation step after heat recovery, and a medium-pressure nitrogen gas for collecting medium-pressure nitrogen gas obtained in the second separation step after heat recovery A recovery step, a low-pressure nitrogen gas recovery step for collecting the low-pressure nitrogen gas obtained in the third separation step after heat recovery, and a high-pressure liquefied nitrogen recovery step for collecting the high-pressure liquefied nitrogen condensed and liquefied in the second indirect heat exchange step. An intermediate-pressure liquefied nitrogen recovery step for collecting the intermediate-pressure liquefied nitrogen condensed and liquefied in the first indirect heat exchange step; and a low-pressure liquefied oxygen recovery step for recovering the low-pressure liquefied oxygen obtained in the third separation step At least one of the steps can be performed.

また、本発明の空気分離装置における第１の構成は、原料空気を深冷液化分離して製品酸素を採取する空気分離装置において、圧縮、精製、冷却した原料空気を低温蒸留して高圧窒素ガスと高圧酸素富化液化空気とに分離する高圧塔と、前記高圧酸素富化液化空気を減圧後に低温蒸留して中圧窒素ガスと中圧酸素富化液化空気とに分離する中圧塔と、前記中圧酸素富化液化空気を減圧した低圧酸素富化液化空気と前記中圧窒素ガスとを間接熱交換させて中圧窒素ガスを凝縮液化して中圧液化窒素を得ると同時に前記低圧酸素富化液化空気を蒸発ガス化して低圧酸素富化空気を得る中圧塔凝縮器と、前記低圧酸素富化空気を低温蒸留して低圧窒素ガスと低圧液化酸素とに分離する低圧塔と、前記高圧窒素ガスと前記低圧液化酸素とを間接熱交換させて前記高圧窒素ガスを凝縮液化して高圧液化窒素を得ると同時に前記低圧液化酸素を蒸発ガス化して低圧酸素ガスを得る主凝縮蒸発器と、前記高圧塔の中間部から抜き出した高圧窒素富化空気と前記中圧酸素富化液化空気とを間接熱交換させて前記高圧窒素富化空気を凝縮液化して高圧窒素富化液化空気を得ると同時に前記中圧酸素富化液化空気を蒸発ガス化して中圧酸素富化空気を得る中圧塔蒸化器と、前記低圧酸素ガス又は前記低圧液化酸素を熱回収後に製品酸素ガスとして採取する製品酸素ガス回収経路とを備えていることを特徴としている。   The first configuration of the air separation device of the present invention is a high pressure nitrogen gas obtained by subjecting the compressed, purified, and cooled raw material air to low-temperature distillation in an air separation device that collects product oxygen by cryogenic liquefaction separation. A high-pressure column that separates the high-pressure oxygen-enriched liquefied air; a medium-pressure column that separates the high-pressure oxygen-enriched liquefied air into medium-pressure nitrogen gas and medium-pressure oxygen-enriched liquefied air by low-temperature distillation after decompression; The low-pressure oxygen-enriched liquefied air obtained by depressurizing the intermediate-pressure oxygen-enriched liquefied air and the intermediate-pressure nitrogen gas are indirectly heat exchanged to condense and liquefy the intermediate-pressure nitrogen gas to obtain the intermediate-pressure liquefied nitrogen and at the same time the low-pressure oxygen A medium pressure column condenser for evaporating and enriching liquefied air to obtain low pressure oxygen enriched air; a low pressure column for separating the low pressure oxygen enriched air into low pressure nitrogen gas and low pressure liquefied oxygen by low temperature distillation; and Indirect heat exchange between high-pressure nitrogen gas and the low-pressure liquefied oxygen A main condensing evaporator that condenses and liquefies the high-pressure nitrogen gas to obtain high-pressure liquefied nitrogen and at the same time evaporates and gasifies the low-pressure liquefied oxygen to obtain low-pressure oxygen gas; Indirect heat exchange between the liquefied air and the medium-pressure oxygen-enriched liquefied air to condense and liquefy the high-pressure nitrogen-enriched air to obtain high-pressure nitrogen-enriched liquefied air, and at the same time evaporate the medium-pressure oxygen-enriched liquefied air A medium-pressure tower evaporator for obtaining medium-pressure oxygen-enriched air, and a product oxygen gas recovery path for collecting the low-pressure oxygen gas or the low-pressure liquefied oxygen as product oxygen gas after heat recovery It is said.

さらに、本発明の空気分離装置における第２の構成は、原料空気を深冷液化分離して製品酸素を採取する空気分離装置において、圧縮、精製、冷却した原料空気を低温蒸留して高圧窒素ガスと高圧酸素富化液化空気とに分離する高圧塔と、前記高圧酸素富化液化空気を減圧後に低温蒸留して中圧窒素ガスと中圧酸素富化液化空気とに分離する中圧塔と、前記中圧酸素富化液化空気を減圧した低圧酸素富化液化空気を低温蒸留して低圧窒素ガスと低圧液化酸素とに分離する低圧塔と、前記中圧窒素ガスと前記低圧塔の中間部を下降する低圧酸素富化還流液化空気とを間接熱交換させて中圧窒素ガスを凝縮液化して中圧液化窒素を得ると同時に前記低圧酸素富化還流液化空気を蒸発ガス化して低圧酸素富化蒸発空気を得る中圧窒素凝縮器と、前記高圧窒素ガスと前記低圧液化酸素とを間接熱交換させて前記高圧窒素ガスを凝縮液化して高圧液化窒素を得ると同時に前記低圧液化酸素を蒸発ガス化して低圧酸素ガスを得る主凝縮蒸発器と、前記高圧塔の中間部から抜き出した高圧窒素富化空気と前記中圧酸素富化液化空気とを間接熱交換させて前記高圧窒素富化空気を凝縮液化して高圧窒素富化液化空気を得ると同時に前記中圧酸素富化液化空気を蒸発ガス化して中圧酸素富化空気を得る中圧塔蒸化器と、前記低圧酸素ガス又は前記低圧液化酸素を熱回収後に製品酸素ガスとして採取する製品ガス回収経路とを備えていることを特徴としている。   Furthermore, the second configuration of the air separation apparatus of the present invention is a high-pressure nitrogen gas obtained by subjecting the compressed, purified, and cooled raw material air to low-temperature distillation in an air separation device that collects product oxygen by cryogenic liquefaction separation. A high-pressure column that separates the high-pressure oxygen-enriched liquefied air; a medium-pressure column that separates the high-pressure oxygen-enriched liquefied air into medium-pressure nitrogen gas and medium-pressure oxygen-enriched liquefied air by low-temperature distillation after decompression; A low-pressure column for separating low-pressure nitrogen gas and low-pressure liquefied oxygen by low-temperature distillation of the low-pressure oxygen-enriched liquefied air obtained by depressurizing the intermediate-pressure oxygen-enriched liquefied air, and an intermediate portion between the intermediate-pressure nitrogen gas and the low-pressure column. Indirect heat exchange with the descending low-pressure oxygen-enriched reflux liquefied air to condense and liquefy medium-pressure nitrogen gas to obtain medium-pressure liquefied nitrogen, and at the same time evaporate and gasify the low-pressure oxygen-enriched reflux liquefied air to enrich low-pressure oxygen A medium pressure nitrogen condenser to obtain evaporated air; A main condensing evaporator that indirectly heat-exchanges the pressurized nitrogen gas and the low-pressure liquefied oxygen to liquefy the high-pressure nitrogen gas to obtain high-pressure liquefied nitrogen and at the same time evaporate and gasify the low-pressure liquefied oxygen to obtain low-pressure oxygen gas; The high-pressure nitrogen-enriched air extracted from the middle part of the high-pressure column and the intermediate-pressure oxygen-enriched liquefied air are indirectly heat exchanged to condense and liquefy the high-pressure nitrogen-enriched air to obtain high-pressure nitrogen-enriched liquefied air At the same time, an intermediate-pressure tower evaporator that obtains intermediate-pressure oxygen-enriched air by evaporating and gasifying the intermediate-pressure oxygen-enriched liquefied air, and collecting the low-pressure oxygen gas or the low-pressure liquefied oxygen as product oxygen gas after heat recovery And a product gas recovery path.

また、本発明の空気分離装置は、前記中圧塔蒸化器に代えて、一方の通路に前記高圧窒素富化空気の一部を上方向に流しながら凝縮液化して得られた液体を下方向に流す低温蒸留を行うことによって前記高圧窒素富化液化空気に加えてより窒素が濃縮した高圧低純窒素ガスを得ると同時に、他方の通路に前記中圧酸素富化液化空気を下方向に流しながら蒸発ガス化して得られたガスを上方向に流す低温蒸留を行うことによって前記中圧酸素富化空気に加えてより酸素が濃縮した中圧低純液化酸素を得る熱交換型蒸留器を用いることができ、前記高圧窒素富化空気に代えて、前記原料空気の一部を使用することもできる。さらに、前記高圧塔で得られた高圧窒素ガスを熱回収後に採取する高圧窒素ガス回収経路、前記中圧塔で得られた中圧窒素ガスを熱回収後に採取する中圧窒素ガス回収経路、前記低圧塔で得られた低圧窒素ガスを熱回収後に採取する低圧窒素ガス回収経路、前記主凝縮蒸発器で凝縮液化した前記高圧液化窒素を採取する高圧液化窒素回収経路、前記中圧塔凝縮器で凝縮液化した前記中圧液化窒素を採取する中圧液化窒素回収経路、前記低圧塔で得られた前記低圧液化酸素を回収する低圧液化酸素回収経路のうち少なくとも１つの経路を設けることができる。   Further, the air separation device of the present invention, instead of the intermediate pressure tower evaporator, lowers the liquid obtained by condensing and liquefying a part of the high-pressure nitrogen-enriched air flowing upward in one passage. In addition to the high-pressure nitrogen-enriched liquefied air, high-pressure low-pure nitrogen gas enriched with nitrogen is obtained by performing low-temperature distillation flowing in the direction, and at the same time, the medium-pressure oxygen-enriched liquefied air is directed downward in the other passage. A heat exchange type distiller that obtains medium-pressure low-pure liquefied oxygen in which oxygen is further concentrated in addition to the medium-pressure oxygen-enriched air by performing low-temperature distillation in which the gas obtained by evaporating gas while flowing is flowed upward. A part of the raw material air can be used instead of the high-pressure nitrogen-enriched air. Further, a high-pressure nitrogen gas recovery path for collecting the high-pressure nitrogen gas obtained in the high-pressure tower after heat recovery, a medium-pressure nitrogen gas recovery path for collecting the medium-pressure nitrogen gas obtained in the medium-pressure tower after heat recovery, A low-pressure nitrogen gas recovery path for collecting the low-pressure nitrogen gas obtained in the low-pressure column after heat recovery, a high-pressure liquefied nitrogen recovery path for sampling the high-pressure liquefied nitrogen condensed and liquefied by the main condensing evaporator, and the intermediate-pressure tower condenser At least one of a medium pressure liquefied nitrogen recovery path for collecting the condensed liquid liquefied nitrogen and a low pressure liquefied oxygen recovery path for recovering the low pressure liquefied oxygen obtained in the low pressure column can be provided.

本発明によれば、第３分離工程を行う低圧塔に供給する低圧酸素富化空気、低圧酸素富化液化空気あるいは低圧塔内部で蒸発する低圧酸素富化蒸発空気の酸素濃度を高くすることができるので、低圧塔の精留条件を改善することができ、第２間接熱交換工程を行う主凝縮蒸発器の交換熱量を小さく抑えることができる。これにより、第１分離工程を行う高圧塔で分離した高圧窒素ガスや、第２分離工程を行う中圧塔で分離した中圧窒素ガスの抜き出し量を多くすることができる。したがって、製品酸素ガスのみを採取する場合は、高圧窒素ガスや中圧窒素ガスを膨張させて動力を回収することにより、装置全体の消費動力を低減することができる。また、高圧窒素ガスや中圧窒素ガスを製品窒素ガスとして採取する場合は、圧力の高い窒素ガスを多く採取できるので、窒素ガス送出用窒素圧縮機の小型化による設備費用の削減や動力費の削減を図ることができる。   According to the present invention, it is possible to increase the oxygen concentration of low-pressure oxygen-enriched air, low-pressure oxygen-enriched liquefied air, or low-pressure oxygen-enriched evaporated air that evaporates inside the low-pressure column supplied to the low-pressure column that performs the third separation step. Therefore, the rectification conditions of the low-pressure column can be improved, and the exchange heat amount of the main condensing evaporator that performs the second indirect heat exchange step can be suppressed to be small. Thereby, the extraction amount of the high-pressure nitrogen gas separated by the high-pressure tower performing the first separation step and the medium-pressure nitrogen gas separated by the medium-pressure tower performing the second separation step can be increased. Therefore, when collecting only product oxygen gas, the power consumption of the entire apparatus can be reduced by recovering power by expanding high-pressure nitrogen gas or medium-pressure nitrogen gas. In addition, when high-pressure nitrogen gas or medium-pressure nitrogen gas is collected as product nitrogen gas, a large amount of high-pressure nitrogen gas can be collected, which reduces equipment costs and power costs by downsizing the nitrogen compressor for sending nitrogen gas. Reduction can be achieved.

本発明の空気分離方法を適用した空気分離装置の第１形態例を示す系統図である。It is a systematic diagram which shows the 1st example of an air separation apparatus to which the air separation method of this invention is applied. 本発明の空気分離方法を適用した空気分離装置の第２形態例を示す系統図である。It is a systematic diagram which shows the 2nd example of an air separation apparatus to which the air separation method of this invention is applied. 本発明の空気分離方法を適用した空気分離装置の第３形態例を示す系統図である。It is a systematic diagram which shows the 3rd example of an air separation apparatus to which the air separation method of this invention is applied. 本発明の空気分離方法を適用した空気分離装置の第４形態例を示す系統図である。It is a systematic diagram which shows the 4th example of an air separation apparatus to which the air separation method of this invention is applied.

まず、図１は、本発明の第１形態例を示すもので、本形態例に示す空気分離装置１０は、３塔式プロセスを採用したものであって、主要機器として、高圧塔１１，中圧塔１２，低圧塔１３，主凝縮蒸発器１４，中圧塔凝縮器１５，中圧塔蒸化器１６，主熱交換器１７，膨張タービン１８及び該膨張タービン１８により駆動されるブロワ１９，過冷器２０を備えており、主凝縮蒸発器１４は高圧塔１１と低圧塔１３との間に、中圧塔凝縮器１５は中圧塔１２の上方に、中圧塔蒸化器１６は中圧塔１２の底部に、それぞれ設けられている。   First, FIG. 1 shows a first embodiment of the present invention, and an air separation device 10 shown in this embodiment adopts a three-column process, and has a high-pressure column 11 as a main equipment. A pressure tower 12, a low pressure tower 13, a main condensation evaporator 14, an intermediate pressure tower condenser 15, an intermediate pressure tower evaporator 16, a main heat exchanger 17, an expansion turbine 18, and a blower 19 driven by the expansion turbine 18, The main condenser evaporator 14 is provided between the high-pressure column 11 and the low-pressure column 13, the intermediate-pressure column condenser 15 is located above the intermediate-pressure column 12, and the intermediate-pressure column evaporator 16 is provided with the supercooler 20. Each is provided at the bottom of the intermediate pressure tower 12.

この空気分離装置は、運転条件を適宜設定して以下に示す各工程を実施することにより、製品として、酸素ガス（ＧＯ２），高圧窒素ガス（ＨＰＧＮ２），中圧窒素ガス（ＭＰＧＮ２），低圧窒素ガス（ＬＰＧＮ２），液化酸素（ＬＯ２），高圧液化窒素（ＨＰＬＮ２），中圧液化窒素（ＭＰＬＮ２），低圧液化酸素（ＬＰＬＯ２）をそれぞれ採取することができる。   In this air separation device, the operating conditions are set as appropriate, and the following steps are carried out. As a product, oxygen gas (GO2), high-pressure nitrogen gas (HPGN2), medium-pressure nitrogen gas (MPGN2), low-pressure nitrogen Gas (LPGN2), liquefied oxygen (LO2), high-pressure liquefied nitrogen (HPLN2), medium-pressure liquefied nitrogen (MPLN2), and low-pressure liquefied oxygen (LPLO2) can be collected.

まず、原料空気（ＡＩＲ）は、空気圧縮機２１であらかじめ設定された高い圧力に圧縮され、空気予冷器２１ａで圧縮熱を除去された後、空気精製器２２で空気中の不純物が除去されて精製される。空気精製器２２から経路Ｌ１に導出された原料空気は、該原料空気の一部が経路Ｌ２に分流して前記ブロワ１９で昇圧された後、ブロワアフタークーラ１９ａで冷却されてから保冷外槽１０ａ内に入って主熱交換器１７に導入される。原料空気の大部分は、そのまま経路Ｌ１を流れて保冷外槽１０ａ内に入り、主熱交換器１７であらかじめ設定された温度に冷却された後、経路Ｌ３を通って高圧塔１１に導入される。   First, the raw material air (AIR) is compressed to a high pressure set in advance by the air compressor 21, the compression heat is removed by the air precooler 21 a, and then impurities in the air are removed by the air purifier 22. Purified. The raw material air led out to the path L1 from the air purifier 22 is partly divided into the path L2 and pressurized by the blower 19 and then cooled by the blower after cooler 19a, and then the cold insulation outer tank 10a. It enters into the main heat exchanger 17. Most of the raw material air flows through the path L1 as it is, enters the cold insulation outer tank 10a, is cooled to a preset temperature by the main heat exchanger 17, and is then introduced into the high pressure column 11 through the path L3. .

高圧塔１１では、原料空気を低温蒸留して塔頂部の高圧窒素ガスと塔底部の高圧酸素富化液化空気とに分離する第１分離工程が行われる。高圧塔１１の底部から経路Ｌ４に抜き出された高圧酸素富化液化空気は、経路Ｌ５と経路Ｌ６とに分流し、経路Ｌ５の高圧酸素富化液化空気は、減圧弁２３であらかじめ設定された中間圧力に減圧された後、前記中圧塔１２に導入される。また、経路Ｌ６の高圧酸素富化液化空気は、過冷器２０で冷却された後、減圧弁２４であらかじめ設定された低い圧力に減圧されてから前記低圧塔１３に導入される。   In the high pressure column 11, a first separation step is performed in which the raw air is distilled at low temperature and separated into high pressure nitrogen gas at the top of the column and high pressure oxygen-enriched liquefied air at the bottom of the column. The high-pressure oxygen-enriched liquefied air extracted from the bottom of the high-pressure column 11 to the path L4 is divided into the path L5 and the path L6, and the high-pressure oxygen-enriched liquefied air in the path L5 is preset by the pressure reducing valve 23. After being reduced to an intermediate pressure, it is introduced into the intermediate pressure tower 12. The high-pressure oxygen-enriched liquefied air in the path L6 is cooled by the supercooler 20 and then reduced to a low pressure set in advance by the pressure reducing valve 24 before being introduced into the low-pressure column 13.

前記中圧塔１２では、中間圧力に減圧されて導入された高圧酸素富化液化空気を低温蒸留して塔頂部の中圧窒素ガスと塔底部の中圧酸素富化液化空気とに分離する第２分離工程が行われる。中圧塔１２の上方に設けられた中圧塔凝縮器１５には、中圧塔１２の頂部から経路Ｌ７に抜き出された中圧窒素ガスと、中圧塔１２の底部から経路Ｌ８に抜き出した中圧酸素富化液化空気の一部を減圧弁２５で減圧した後の低圧酸素富化液化空気とが導入される。   In the intermediate pressure tower 12, the high pressure oxygen-enriched liquefied air introduced after being depressurized to an intermediate pressure is subjected to low-temperature distillation to separate into medium-pressure nitrogen gas at the top of the tower and medium-pressure oxygen-enriched liquefied air at the bottom of the tower. Two separation steps are performed. The intermediate pressure tower condenser 15 provided above the intermediate pressure tower 12 is extracted with medium pressure nitrogen gas extracted from the top of the intermediate pressure tower 12 into the path L7 and extracted from the bottom of the intermediate pressure tower 12 into the path L8. In addition, low-pressure oxygen-enriched liquefied air that has been partially depressurized by the pressure reducing valve 25 is introduced.

中圧塔凝縮器１５では、前記低圧酸素富化液化空気と前記中圧窒素ガスとが間接熱交換を行い、中圧窒素ガスを凝縮液化して中圧液化窒素を得ると同時に低圧酸素富化液化空気を蒸発ガス化して低圧酸素富化空気を得る第１間接熱交換工程が行われる。中圧塔凝縮器１５で凝縮液化した中圧液化窒素は、経路Ｌ９を通って中圧塔１２に戻され、中圧塔１２の下降液となる。また、中圧液化窒素の一部は、経路Ｌ１０に抜き出され、過冷器２０で冷却された後、減圧弁２６で減圧されてから前記低圧塔１３に導入される。中圧塔凝縮器１５で蒸発ガス化した低圧酸素富化空気は、経路Ｌ１１を通って前記低圧塔１３に導入される。また、中圧塔凝縮器１５で蒸発ガス化する前の低圧酸素富化液化空気の一部が経路Ｌ１２に抜き出されて低圧塔１３に導入される。   In the intermediate-pressure tower condenser 15, the low-pressure oxygen-enriched liquefied air and the intermediate-pressure nitrogen gas perform indirect heat exchange to condense and liquefy the intermediate-pressure nitrogen gas to obtain intermediate-pressure liquefied nitrogen and at the same time low-pressure oxygen enrichment. A first indirect heat exchange step is performed in which liquefied air is vaporized to obtain low-pressure oxygen-enriched air. The intermediate-pressure liquefied nitrogen condensed and liquefied by the intermediate-pressure tower condenser 15 is returned to the intermediate-pressure tower 12 through the path L9 and becomes the descending liquid of the intermediate-pressure tower 12. A part of the medium-pressure liquefied nitrogen is extracted to the path L10, cooled by the supercooler 20, and then reduced in pressure by the pressure reducing valve 26 before being introduced into the low pressure column 13. The low-pressure oxygen-enriched air evaporated and gasified in the intermediate-pressure tower condenser 15 is introduced into the low-pressure tower 13 through the path L11. A part of the low-pressure oxygen-enriched liquefied air before evaporating and gasifying in the intermediate-pressure tower condenser 15 is extracted into the path L12 and introduced into the low-pressure tower 13.

低圧塔１３には、前記経路Ｌ６，Ｌ１０，Ｌ１１，Ｌ１２からの各種流体の他、前記ブロワ１９で昇圧し、主熱交換器１７で冷却された後に前記膨張タービン１８で断熱膨張した原料空気が経路Ｌ１３から、前記高圧塔１１の下降液の一部を中間部から抜き出して過冷器２０で冷却し、減圧弁２７で減圧された液流体が経路Ｌ１４からそれぞれ導入され、低圧塔１３では、前記低圧酸素富化空気を主とするこれらの流体を低温蒸留して塔頂部の低圧窒素ガスと塔底部の低圧液化酸素とに分離する第３分離工程が行われる。   In addition to the various fluids from the paths L6, L10, L11, and L12, the low-pressure tower 13 includes raw material air that has been pressurized by the blower 19 and cooled by the main heat exchanger 17 and then adiabatically expanded by the expansion turbine 18. From the path L13, a part of the descending liquid of the high-pressure column 11 is extracted from the intermediate part, cooled by the supercooler 20, and the liquid fluid decompressed by the pressure reducing valve 27 is introduced from the path L14. A third separation step is performed in which these fluids mainly composed of the low-pressure oxygen-enriched air are subjected to low-temperature distillation to separate low-pressure nitrogen gas at the top of the column and low-pressure liquefied oxygen at the bottom of the column.

低圧塔１３の底部の低圧液化酸素と、前記高圧塔１１の頂部から経路Ｌ１５に抜き出された前記高圧窒素ガスとは、前記主凝縮蒸発器１４で間接熱交換を行い、前記高圧窒素ガスを凝縮液化して高圧液化窒素を得ると同時に前記低圧液化酸素を蒸発ガス化して低圧酸素ガスを得る第２間接熱交換工程が行われる。主凝縮蒸発器１４で凝縮液化した高圧液化窒素は、経路Ｌ１６を通って高圧塔１１に戻され、高圧塔１１の下降液となる。   The low-pressure liquefied oxygen at the bottom of the low-pressure column 13 and the high-pressure nitrogen gas extracted from the top of the high-pressure column 11 to the path L15 are subjected to indirect heat exchange by the main condensing evaporator 14, and the high-pressure nitrogen gas is A second indirect heat exchange step is performed in which high pressure liquefied nitrogen is obtained by condensing and liquefying, and at the same time the low pressure liquefied oxygen is vaporized to obtain low pressure oxygen gas. The high-pressure liquefied nitrogen condensed and liquefied by the main condensing evaporator 14 is returned to the high-pressure column 11 through the path L16 and becomes the descending liquid of the high-pressure column 11.

一方、前記中圧塔１２の底部に分離した前記中圧酸素富化液化空気の残部と、前記高圧塔１１における第１分離工程の中間段階で高圧塔１１の下部から経路１７に抜き出した高圧窒素富化空気の一部とは、前記中圧塔蒸化器１６で間接熱交換を行い、前記高圧窒素富化空気を凝縮液化して高圧窒素富化液化空気を得ると同時に前記中圧酸素富化液化空気を蒸発ガス化して中圧酸素富化空気を得る第３間接熱交換工程が行われる。中圧塔蒸化器１６で蒸発ガス化した中圧酸素富化空気は中圧塔１２の上昇ガスとなり、中圧塔蒸化器１６で凝縮液化した高圧窒素富化液化空気は、経路Ｌ１８を通って高圧塔１１に戻され、高圧塔１１の下降液となる。   On the other hand, the remainder of the medium-pressure oxygen-enriched liquefied air separated at the bottom of the medium-pressure column 12 and high-pressure nitrogen extracted from the lower part of the high-pressure column 11 into the path 17 in the intermediate stage of the first separation step in the high-pressure column 11 The part of the enriched air is indirectly heat exchanged by the intermediate pressure tower evaporator 16 to condense and liquefy the high pressure nitrogen enriched air to obtain the high pressure nitrogen enriched liquefied air, and at the same time the medium pressure oxygen enriched A third indirect heat exchange step is performed in which the liquefied liquefied air is vaporized to obtain medium pressure oxygen-enriched air. The medium-pressure oxygen-enriched air evaporated and gasified in the medium-pressure tower evaporator 16 becomes the rising gas of the medium-pressure tower 12, and the high-pressure nitrogen-enriched liquefied air condensed and liquefied in the medium-pressure tower evaporator 16 passes through the path L18. It returns to the high pressure column 11 and becomes a descending liquid of the high pressure column 11.

また、高圧塔１１の頂部から主凝縮蒸発器１４に導入されて凝縮液化した高圧液化窒素の一部を経路Ｌ１９に抜き出し、過冷器２０で冷却して減圧弁２８で減圧後に低圧塔１３に導入したり、前記経路Ｌ８を流れる中圧酸素富化液化空気の一部を経路Ｌ２０に分流し、減圧弁２９で減圧してから低圧塔１３に導入したり、経路Ｌ１８を流れる高圧窒素富化液化空気の一部を経路Ｌ２１に分流し、過冷器２０で冷却して減圧弁３０で減圧してから低圧塔１３に導入したりすることもできる。   Further, a part of the high-pressure liquefied nitrogen introduced into the main condensing evaporator 14 from the top of the high-pressure column 11 and extracted into the path L19 is cooled by the supercooler 20 and reduced in pressure by the pressure reducing valve 28. Or a part of the medium-pressure oxygen-enriched liquefied air flowing through the path L8 is divided into the path L20 and decompressed by the pressure reducing valve 29 and then introduced into the low-pressure column 13, or the high-pressure nitrogen-enriched flowing through the path L18. A part of the liquefied air can be divided into the path L21, cooled by the supercooler 20, reduced in pressure by the pressure reducing valve 30, and then introduced into the low pressure column 13.

前記主凝縮蒸発器１４で蒸発ガス化した低圧酸素ガスは、一部が製品酸素ガス回収経路Ｌ２２に抜き出されて主熱交換器１７で熱回収された後、製品酸素ガス（ＧＯ２）として採取され、残部の低圧酸素ガスは低圧塔１３の上昇ガスとなる。また、低圧塔１３の頂部からは、低圧窒素ガスが低圧窒素ガス回収経路Ｌ２３に抜き出されて過冷器２０及び主熱交換器１７で熱回収された後、製品低圧窒素ガス（ＬＰＧＮ２）として採取される。さらに、高圧塔１１の頂部からは、高圧窒素ガスの一部が高圧窒素ガス回収経路Ｌ２４に抜き出されて主熱交換器１７で熱回収された後、製品高圧窒素ガス（ＨＰＧＮ２）として採取される。   A part of the low-pressure oxygen gas evaporated and gasified by the main condenser evaporator 14 is extracted into the product oxygen gas recovery path L22 and recovered by the main heat exchanger 17, and then collected as product oxygen gas (GO2). The remaining low-pressure oxygen gas becomes the rising gas of the low-pressure column 13. Further, from the top of the low-pressure column 13, low-pressure nitrogen gas is extracted to the low-pressure nitrogen gas recovery path L23 and is recovered by the supercooler 20 and the main heat exchanger 17, and then as product low-pressure nitrogen gas (LPGN2). Collected. Further, a part of the high-pressure nitrogen gas is extracted from the top of the high-pressure tower 11 to the high-pressure nitrogen gas recovery path L24 and recovered by the main heat exchanger 17, and then collected as product high-pressure nitrogen gas (HPGN2). The

また、必要に応じて、前記中圧塔１２で得られた中圧窒素ガスの一部を熱回収後に製品中圧窒素ガス（ＭＰＧＮ２）として採取する中圧窒素ガス回収経路Ｌ２５、前記主凝縮蒸発器１４で凝縮液化した高圧液化窒素の一部を製品高圧液化窒素（ＨＰＬＮ２）として採取する高圧液化窒素回収経路Ｌ２６、前記中圧塔凝縮器１５で凝縮液化した中圧液化窒素の一部を製品中圧液化窒素（ＭＰＬＮ２）として採取する中圧液化窒素回収経路Ｌ２７、前記低圧塔１１で得られた低圧液化酸素の一部を製品低圧液化酸素（ＬＰＬＯ２）として回収する低圧液化酸素回収経路Ｌ２８を設け、中圧窒素ガス回収工程、高圧液化窒素回収工程、中圧液化窒素回収工程、低圧液化酸素回収工程をそれぞれ行うこともできる。さらに、低圧塔１３の上部から経路Ｌ２９に廃ガス（ＷＧ）を抜き出すこともできる。   Further, if necessary, an intermediate pressure nitrogen gas recovery path L25 for collecting a part of the intermediate pressure nitrogen gas obtained in the intermediate pressure tower 12 as a product intermediate pressure nitrogen gas (MPGN2) after heat recovery, the main condensation evaporation High pressure liquefied nitrogen recovery path L26 for collecting a part of the high pressure liquefied nitrogen condensed and liquefied in the vessel 14 as product high pressure liquefied nitrogen (HPLN2), a part of the medium pressure liquefied nitrogen condensed and liquefied by the medium pressure tower condenser 15 An intermediate pressure liquefied nitrogen recovery path L27 for collecting as medium pressure liquefied nitrogen (MPLN2), and a low pressure liquefied oxygen recovery path L28 for recovering a part of the low pressure liquefied oxygen obtained in the low pressure column 11 as product low pressure liquefied oxygen (LPLO2). An intermediate pressure nitrogen gas recovery step, a high pressure liquefied nitrogen recovery step, an intermediate pressure liquefied nitrogen recovery step, and a low pressure liquefied oxygen recovery step can also be performed. Furthermore, waste gas (WG) can be extracted from the upper part of the low-pressure column 13 to the path L29.

このように構成した空気分離装置１０において、特に、中圧塔１２の底部に分離した中圧酸素富化液化空気を蒸発ガス化させるための温流体として、高圧塔１１の高圧窒素ガスよりも酸素濃度が高く、温度が高い高圧窒素富化空気、好ましくは酸素濃度が８モル％以上、さらに好ましくは１１モル％以上の高圧窒素富化空気を高圧塔１１の中間部から抜き出して使用し、中圧酸素富化液化空気の温度を、低圧塔１３底部の低圧液化酸素の温度よりも高くすることにより、中圧塔１２の底部から経路Ｌ８に抜き出される中圧酸素富化液化空気の酸素濃度、及び、中圧酸素富化液化空気を減圧後に中圧塔凝縮器１５で蒸発ガス化した低圧酸素富化空気の酸素濃度を高くすることができる。   In the air separation apparatus 10 configured as described above, in particular, oxygen as a warm fluid for evaporating and gasifying the medium-pressure oxygen-enriched liquefied air separated at the bottom of the medium-pressure tower 12 is higher than the high-pressure nitrogen gas in the high-pressure tower 11. High-pressure nitrogen-enriched air having a high concentration and high temperature, preferably high-pressure nitrogen-enriched air having an oxygen concentration of 8 mol% or more, more preferably 11 mol% or more, is extracted from the intermediate portion of the high-pressure column 11 and used. The oxygen concentration of the medium-pressure oxygen-enriched liquefied air extracted from the bottom of the medium-pressure tower 12 to the path L8 by making the temperature of the pressure-enriched liquefied air higher than the temperature of the low-pressure liquefied oxygen at the bottom of the low-pressure column 13 The oxygen concentration of the low-pressure oxygen-enriched air obtained by evaporating and gasifying the intermediate-pressure oxygen-enriched liquefied air after evaporating in the intermediate-pressure tower condenser 15 can be increased.

したがって、前述の各工程を実施することにより、低圧塔１３に経路Ｌ１１を介して供給する低圧酸素富化空気の酸素濃度を高くすることができるので、低圧塔１３の精留条件を改善することができ、消費動力を削減しながら主凝縮蒸発器１４の交換熱量を小さく抑えることができる。これにより、高圧塔１１の頂部から導出可能な高圧窒素ガスや中圧塔１２の頂部から導出可能な中圧窒素ガスの採取量を増加させることができ、これらの高圧又は中圧窒素ガスを膨張させて動力を回収することにより、例えば窒素ガスを膨張させた動力を原料空気の圧縮に用いたりすることにより、空気圧縮機２１の消費動力の削減を図ることができる。また、これらの高圧又は中圧窒素ガスを製品として圧送する場合には、窒素圧縮機の消費動力の削減や小型化を図ることができる。   Therefore, the oxygen concentration of the low-pressure oxygen-enriched air supplied to the low-pressure column 13 via the path L11 can be increased by performing the above-described steps, so that the rectification conditions of the low-pressure column 13 are improved. The amount of exchange heat of the main condensing evaporator 14 can be kept small while reducing power consumption. As a result, the amount of high-pressure nitrogen gas that can be derived from the top of the high-pressure column 11 and medium-pressure nitrogen gas that can be derived from the top of the intermediate-pressure column 12 can be increased, and the high-pressure or medium-pressure nitrogen gas can be expanded. Thus, by recovering the power, for example, by using the power obtained by expanding the nitrogen gas for compressing the raw material air, the power consumption of the air compressor 21 can be reduced. Moreover, when these high-pressure or medium-pressure nitrogen gas is pumped as a product, the power consumption of the nitrogen compressor can be reduced and the size can be reduced.

図２は、本発明の第２形態例を示している。なお、以下の説明において、前記第１形態例に示した空気分離装置の構成要素と同一の構成要素には同一の符号を付して詳細な説明は省略する。   FIG. 2 shows a second embodiment of the present invention. In the following description, the same components as those of the air separation device shown in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

本形態例に示す空気分離装置は、前記第１形態例における中圧塔蒸化器１６に導入する温流体を、高圧塔１１の中間部から経路Ｌ１７に抜き出した前記高圧窒素富化空気に代えて、主熱交換器１７で冷却された後の原料空気の一部を使用した例を示している。   In the air separation device shown in the present embodiment, the hot fluid introduced into the intermediate pressure tower evaporator 16 in the first embodiment is replaced with the high-pressure nitrogen-enriched air extracted from the intermediate portion of the high-pressure tower 11 to the path L17. In this example, a part of the raw material air after being cooled by the main heat exchanger 17 is used.

主熱交換器１７で冷却された原料空気の一部は、前記経路Ｌ３から経路Ｌ３１に分流して中圧塔蒸化器１６に導入され、残部の原料空気の大部分は、そのまま経路Ｌ３を進んで高圧塔１１に導入される。中圧塔蒸化器１６では、経路Ｌ３１からの原料空気と中圧塔１２で塔底部に分離した前記中圧酸素富化液化空気とが間接熱交換を行い、前記中圧酸素富化液化空気を蒸発ガス化して中圧酸素富化空気を得ると同時に原料空気を凝縮液化して原料液化空気を得る前記第３間接熱交換工程と同様の工程が行われる。中圧塔蒸化器１６で蒸発ガス化した中圧酸素富化空気は、前記同様に中圧塔１２の上昇ガスとなり、中圧塔蒸化器１６で凝縮液化した原料液化空気は、経路Ｌ３２を通って高圧塔１１に下降液として導入される。   Part of the raw material air cooled by the main heat exchanger 17 is branched from the path L3 to the path L31 and introduced into the intermediate pressure tower evaporator 16, and most of the remaining raw material air passes through the path L3 as it is. It proceeds and is introduced into the high pressure column 11. In the intermediate pressure tower evaporator 16, the raw air from the path L31 and the intermediate pressure oxygen-enriched liquefied air separated at the bottom of the intermediate pressure tower 12 perform indirect heat exchange, and the intermediate pressure oxygen-enriched liquefied air is obtained. Is vaporized to obtain medium-pressure oxygen-enriched air, and at the same time, the same step as the third indirect heat exchange step in which raw material air is condensed and liquefied to obtain raw material liquefied air is performed. The medium-pressure oxygen-enriched air evaporated and gasified in the intermediate-pressure tower evaporator 16 becomes the rising gas of the intermediate-pressure tower 12 as described above, and the raw material liquefied air condensed and liquefied in the intermediate-pressure tower evaporator 16 is route L32. And is introduced into the high pressure column 11 as a descending liquid.

本形態例においても、製品酸素ガス回収経路Ｌ２２から製品酸素ガスが、低圧窒素ガス回収経路Ｌ２３から製品低圧窒素ガスが、高圧窒素ガス回収経路Ｌ２４から製品窒素ガスがそれぞれ採取される。また、図示は省略するが、前記同様に、製品中圧窒素ガス、製品高圧液化窒素、製品中圧液化窒素、製品低圧液化酸素を採取することや廃ガスを抜き出すことも可能である。   Also in this embodiment, the product oxygen gas is collected from the product oxygen gas recovery path L22, the product low-pressure nitrogen gas is collected from the low-pressure nitrogen gas recovery path L23, and the product nitrogen gas is collected from the high-pressure nitrogen gas recovery path L24. Moreover, although illustration is abbreviate | omitted, it is also possible to extract | collect product intermediate pressure nitrogen gas, product high pressure liquefied nitrogen, product intermediate pressure liquefied nitrogen, product low pressure liquefied oxygen, and to extract waste gas like the above.

本形態例に示すように、中圧塔蒸化器１６で中圧酸素富化液化空気と間接熱交換を行う温流体に原料空気の一部を用いることにより、中圧塔蒸化器１６における温流体の組成を一定にして温流体の温度を安定したものとすることができるので、中圧塔蒸化器１６の負荷変動が抑えられ、中圧塔１２の操作性を改善することができる。したがって、外乱によって高圧塔１１の濃度分布が変動するようなことがあっても、中圧塔１２を安定した運転状態に保持することができる。   As shown in the present embodiment, by using a part of the raw material air as a warm fluid that performs indirect heat exchange with the medium-pressure oxygen-enriched liquefied air in the medium-pressure tower evaporator 16, Since the temperature of the warm fluid can be stabilized by making the composition of the warm fluid constant, the load fluctuation of the intermediate pressure tower evaporator 16 can be suppressed, and the operability of the intermediate pressure tower 12 can be improved. . Therefore, even if the concentration distribution of the high pressure column 11 fluctuates due to disturbance, the intermediate pressure column 12 can be maintained in a stable operation state.

図３は、本発明の第３形態例を示すもので、前記中圧塔蒸化器１６に代えて熱交換型蒸留器３１を使用した例を示している。熱交換型蒸留器３１は、ガス状の温流体が上向流で流れる第１通路３２と液状の冷流体が下降流で流れる第２通路３３とを備えるもので、本形態例では、第１通路３２に原料空気を、第２通路３２に中圧酸素富化液化空気をそれぞれ導入している。   FIG. 3 shows a third embodiment of the present invention, and shows an example in which a heat exchange type distiller 31 is used in place of the intermediate pressure tower evaporator 16. The heat exchange-type distiller 31 includes a first passage 32 in which a gaseous warm fluid flows in an upward flow and a second passage 33 in which a liquid cold fluid flows in a downward flow. Source air is introduced into the passage 32 and medium-pressure oxygen-enriched liquefied air is introduced into the second passage 32, respectively.

すなわち、高圧塔１１に向かう前記経路Ｌ３から経路Ｌ３１に分流した原料空気の一部は、熱交換型蒸留器３１の下部から第１通路３２に上向流として導入され、該第１通路３２を上向きに流れる間に第２通路３３を流れる中圧酸素富化液化空気と間接熱交換を行う。この間接熱交換で原料空気の一部が凝縮液化し、第１通路３２を下向きに流れることによって第１通路３２内で低温蒸留が行われ、第１通路３２を上昇するガス中に窒素が濃縮し、第１通路３２を流下する液中に酸素が濃縮する。第１通路３２を上昇する窒素が濃縮したガス（高圧低純窒素ガス）は経路Ｌ３４に抜き出され、弁３４を通って高圧塔１１に導入される。また、第１通路３２を流下する酸素が濃縮した液は経路Ｌ３５に抜き出され、高圧塔１１の底部から抜き出されて経路Ｌ４を流れる高圧酸素富化液化空気と合流する。なお、弁３４は、熱交換型蒸留器３１の第１通路３２の一次側に設けてもよい。   That is, a part of the raw material air diverted from the path L3 toward the high-pressure tower 11 to the path L31 is introduced as an upward flow into the first passage 32 from the lower part of the heat-exchange distiller 31, and passes through the first passage 32. While flowing upward, indirect heat exchange with the medium pressure oxygen-enriched liquefied air flowing through the second passage 33 is performed. By this indirect heat exchange, part of the raw material air is condensed and liquefied, and flows downward through the first passage 32, whereby low-temperature distillation is performed in the first passage 32, and nitrogen is concentrated in the gas rising in the first passage 32. Then, oxygen is concentrated in the liquid flowing down the first passage 32. A gas (high-pressure low-pure nitrogen gas) enriched with nitrogen rising through the first passage 32 is extracted into the path L34 and introduced into the high-pressure column 11 through the valve 34. Also, the oxygen-concentrated liquid flowing down the first passage 32 is extracted to the path L35, and extracted from the bottom of the high-pressure tower 11 and merged with the high-pressure oxygen-enriched liquefied air flowing through the path L4. The valve 34 may be provided on the primary side of the first passage 32 of the heat exchange type still 31.

一方、中圧塔１２の底部から経路Ｌ３６に抜き出された中圧酸素富化液化空気は、熱交換型蒸留器３１の上部から第２通路３３に下向流として導入され、該第２通路３３を下向きに流れる間に第１通路３２を流れる原料空気と間接熱交換を行う。この間接熱交換で中圧酸素富化液化空気の一部が蒸発ガス化し、第２通路３３を上向きに流れることによって第２通路３３内で低温蒸留が行われ、第２通路３３を上昇するガス中に窒素が濃縮し、第２通路３３を流下する液中に酸素が濃縮する。第２通路３３を上昇する窒素が濃縮したガスは経路Ｌ３７に抜き出され、中圧塔１２に上昇ガスとして導入される。また、第２通路３３を流下する酸素が濃縮した液（中圧低純液化酸素）は経路Ｌ３８に抜き出され、減圧弁３５で低圧に減圧されて中圧塔凝縮器１５に導入される。さらに、酸素が濃縮した液は、必要に応じて経路Ｌ３８から経路Ｌ３９に分流させ、減圧弁３６で低圧に減圧されて低圧塔１３に導入することができる。   On the other hand, the medium-pressure oxygen-enriched liquefied air extracted from the bottom of the intermediate-pressure tower 12 to the path L36 is introduced as a downward flow into the second passage 33 from the upper part of the heat exchange-type distiller 31, and the second passage Indirect heat exchange with the raw material air flowing through the first passage 32 is performed while flowing downward through 33. A gas that evaporates part of the medium-pressure oxygen-enriched liquefied air by this indirect heat exchange and flows upward in the second passage 33, thereby performing low temperature distillation in the second passage 33 and raising the second passage 33. Nitrogen is concentrated therein, and oxygen is concentrated in the liquid flowing down the second passage 33. A gas enriched with nitrogen rising through the second passage 33 is extracted into the path L37 and introduced into the intermediate pressure tower 12 as a rising gas. Further, a liquid (medium-pressure low-pure liquefied oxygen) in which oxygen flowing down the second passage 33 is concentrated is extracted into a path L38, and is reduced to a low pressure by the pressure-reducing valve 35 and introduced into the intermediate-pressure tower condenser 15. Furthermore, the oxygen-enriched liquid can be diverted from the path L38 to the path L39 as necessary, and the pressure can be reduced to a low pressure by the pressure reducing valve 36 and introduced into the low pressure column 13.

このように、中圧塔蒸化器１６に代えて熱交換型蒸留器３１を使用することにより、第１通路３２で窒素が濃縮したガスを高圧塔１１に供給できるので、高圧塔１１の精留条件を改善できるとともに、第２通路３３で酸素が濃縮した液を中圧塔凝縮器１５に導入して蒸発ガス化したガスを低圧塔１３に供給できるので、低圧塔１３の精留条件も改善できる。また、原料空気に代えて、前記第１形態例と同様に、高圧塔１１の中間部から抜き出した高圧窒素富化空気を温流体として使用することもできる。この場合も、第１通路３２で窒素が濃縮したガス及び凝縮液化した液を高圧塔１１に戻したり、凝縮液化した液の一部を分流して過冷器２０で冷却後、減圧してから低圧塔１３に導入してもよい。また、本形態例においても、前記第１形態例と同様に、各種ガス製品や液製品を採取することが可能である。   In this way, by using the heat exchange type distiller 31 in place of the intermediate pressure tower evaporator 16, the gas enriched with nitrogen in the first passage 32 can be supplied to the high pressure tower 11. The distillation conditions can be improved, and the gas concentrated in the second passage 33 can be introduced into the intermediate pressure tower condenser 15 to supply the vaporized gas to the low pressure tower 13. Can improve. Moreover, it can replace with raw material air and can use the high pressure nitrogen enriched air extracted from the intermediate part of the high pressure column 11 as a warm fluid like the said 1st example. Also in this case, the nitrogen-concentrated gas and condensed liquid in the first passage 32 are returned to the high-pressure tower 11, or a part of the condensed liquid is diverted and cooled by the subcooler 20 and then decompressed. It may be introduced into the low pressure column 13. Also in this embodiment, various gas products and liquid products can be collected as in the first embodiment.

図４は、本発明の第４形態例を示すもので、中圧塔１２の頂部に生成した中圧窒素ガスを凝縮させるための冷流体として低圧塔１３の中間部を流下する低圧酸素富化還流液化空気を使用した例を示している。   FIG. 4 shows a fourth embodiment of the present invention, in which low-pressure oxygen enrichment flows down the intermediate portion of the low-pressure column 13 as a cold fluid for condensing the medium-pressure nitrogen gas generated at the top of the medium-pressure column 12. An example using reflux liquefied air is shown.

低圧塔１３の中間部で、低圧塔１３内に各種流体が流入する位置より下方には、中圧窒素凝縮器４１が設けられており、中圧塔１２の頂部から経路Ｌ４１に抜き出された中圧窒素ガスが中圧窒素凝縮器４１に導入され、低圧塔１３内を流下する低圧酸素富化還流液化空気の一部と間接熱交換を行うことにより凝縮液化して中圧液化窒素になるとともに、低圧酸素富化還流液化空気を蒸発ガス化して低圧酸素富化蒸発空気とする。凝縮液化した中圧液化窒素は、経路Ｌ４２を通って中圧塔１２の上部に下降液として導入され、一部の中圧液化窒素は、経路Ｌ４３に分流して過冷器２０を通り、減圧弁４２で減圧された後に低圧塔１３に導入される。さらに、過冷器２０で過冷却状態となった中圧液化窒素の一部を、経路Ｌ４４に分流して製品中圧液化窒素として採取することもできる。また、蒸発ガス化した低圧酸素富化蒸発空気は、低圧塔１３内の上昇ガスとなる。一方、中圧塔１２の底部から経路Ｌ４５に抜き出された中圧酸素富化液化空気は、減圧弁４３で減圧されてから低圧塔１３に導入される。   An intermediate-pressure nitrogen condenser 41 is provided at an intermediate portion of the low-pressure column 13 and below a position where various fluids flow into the low-pressure column 13, and is extracted from the top of the intermediate-pressure column 12 to the path L41. Medium-pressure nitrogen gas is introduced into the medium-pressure nitrogen condenser 41, and condensed and liquefied by indirect heat exchange with a part of the low-pressure oxygen-enriched reflux liquefied air flowing down in the low-pressure column 13 to become medium-pressure liquefied nitrogen. At the same time, the low-pressure oxygen-enriched reflux liquefied air is vaporized into low-pressure oxygen-enriched evaporated air. The condensed and liquefied intermediate pressure liquefied nitrogen is introduced as a descending liquid into the upper part of the intermediate pressure tower 12 through the path L42, and a part of the intermediate pressure liquefied nitrogen is diverted to the path L43 and passes through the subcooler 20 to be decompressed. The pressure is reduced by the valve 42 and then introduced into the low pressure column 13. Furthermore, a part of the medium-pressure liquefied nitrogen that has been supercooled by the subcooler 20 can be divided into the path L44 and collected as product medium-pressure liquefied nitrogen. Further, the vaporized low-pressure oxygen-enriched evaporated air becomes a rising gas in the low-pressure column 13. On the other hand, the intermediate-pressure oxygen-enriched liquefied air extracted from the bottom of the intermediate-pressure tower 12 to the path L45 is decompressed by the decompression valve 43 and then introduced into the low-pressure tower 13.

このように、中圧塔１２頂部の中圧窒素ガスを凝縮させる冷流体として低圧塔１３の中間部を流下する低圧酸素富化還流液化空気を用いることにより、低圧塔１３に対する中圧窒素凝縮器４１の位置を調整することによって低圧酸素富化還流液化空気の組成を任意に選択することが可能となり、運転条件や設計条件の設定幅を広げることができ、空気分離効率の向上を図ることができる。   Thus, by using the low-pressure oxygen-enriched reflux liquefied air flowing down the middle part of the low-pressure column 13 as the cold fluid for condensing the medium-pressure nitrogen gas at the top of the intermediate-pressure column 12, the medium-pressure nitrogen condenser for the low-pressure column 13 is used. By adjusting the position 41, the composition of the low-pressure oxygen-enriched reflux liquefied air can be arbitrarily selected, the setting range of operating conditions and design conditions can be expanded, and the air separation efficiency can be improved. it can.

なお、各形態例において、高圧の製品酸素ガスを必要とする場合は、主凝縮蒸発器１４で蒸発ガス化した低圧酸素ガスを採取することに代えて、低圧塔１３の底部から低圧液化酸素を抜き出し、液化酸素ポンプによって低圧液化酸素を所望の圧力に昇圧して高圧液化酸素とした後、主熱交換器１７で蒸発ガス化させることにより、製品高圧酸素ガスとして採取することができる。これにより、高価な酸素圧縮機を設置する必要がなくなり、設備コストの上昇を抑えることができる。また、各種流体を間接熱交換させる主凝縮蒸発器、中圧塔凝縮器、中圧塔蒸化器などに使用する熱交換器の形式は任意であり、各種様式の熱交換器を使用することができる。   In each embodiment, when high-pressure product oxygen gas is required, instead of collecting the low-pressure oxygen gas evaporated by the main condenser evaporator 14, low-pressure liquefied oxygen is supplied from the bottom of the low-pressure column 13. After extracting and raising the low-pressure liquefied oxygen to a desired pressure by a liquefied oxygen pump to form high-pressure liquefied oxygen, the main heat exchanger 17 can evaporate and gasify it to obtain a product high-pressure oxygen gas. Thereby, it is not necessary to install an expensive oxygen compressor, and an increase in equipment cost can be suppressed. In addition, the type of heat exchanger used for the main condensing evaporator, medium pressure tower condenser, medium pressure tower evaporator, etc. for indirect heat exchange of various fluids is arbitrary, and various types of heat exchangers should be used. Can do.

１０…空気分離装置、１０ａ…保冷外槽、１１…高圧塔、１２…中圧塔、１３…低圧塔、１４…主凝縮蒸発器、１５…中圧塔凝縮器、１６…中圧塔蒸化器、１７…主熱交換器、１８…膨張タービン、１９…ブロワ、１９ａ…ブロワアフタークーラ、２０…過冷器、２１…空気圧縮機、２１ａ…空気予冷器、２２…空気精製器、２３，２４，２５，２６，２７，２８，２９，３０…減圧弁、３１…熱交換型蒸留器、３２…第１通路、３３…第２通路、３４…弁、３５，３６，３７…減圧弁、４１…中圧窒素凝縮器、４２，４３…減圧弁   DESCRIPTION OF SYMBOLS 10 ... Air separation apparatus, 10a ... Cold storage outer tank, 11 ... High pressure tower, 12 ... Medium pressure tower, 13 ... Low pressure tower, 14 ... Main condensation evaporator, 15 ... Medium pressure tower condenser, 16 ... Medium pressure tower evaporation 17 ... Main heat exchanger, 18 ... Expansion turbine, 19 ... Blower, 19a ... Blower after cooler, 20 ... Subcooler, 21 ... Air compressor, 21a ... Air precooler, 22 ... Air purifier, 23, 24, 25, 26, 27, 28, 29, 30 ... pressure reducing valve, 31 ... heat exchange type distiller, 32 ... first passage, 33 ... second passage, 34 ... valve, 35, 36, 37 ... pressure reducing valve, 41 ... Medium pressure nitrogen condenser, 42, 43 ... Pressure reducing valve

Claims (10)

原料空気を深冷液化分離して製品酸素を採取する空気分離方法において、
圧縮、精製、冷却した原料空気を低温蒸留して高圧窒素ガスと高圧酸素富化液化空気とに分離する第１分離工程と、
前記高圧酸素富化液化空気を減圧後に低温蒸留して中圧窒素ガスと中圧酸素富化液化空気とに分離する第２分離工程と、
前記中圧酸素富化液化空気を減圧した低圧酸素富化液化空気と前記中圧窒素ガスとを間接熱交換させて中圧窒素ガスを凝縮液化して中圧液化窒素を得ると同時に前記低圧酸素富化液化空気を蒸発ガス化して低圧酸素富化空気を得る第１間接熱交換工程と、
前記低圧酸素富化空気を低温蒸留して低圧窒素ガスと低圧液化酸素とに分離する第３分離工程と、
前記高圧窒素ガスと前記低圧液化酸素とを間接熱交換させて前記高圧窒素ガスを凝縮液化して高圧液化窒素を得ると同時に前記低圧液化酸素を蒸発ガス化して低圧酸素ガスを得る第２間接熱交換工程と、
前記第１分離工程の中間段階で生成した高圧窒素富化空気と前記中圧酸素富化液化空気とを間接熱交換させて前記高圧窒素富化空気を凝縮液化して高圧窒素富化液化空気を得ると同時に前記中圧酸素富化液化空気を蒸発ガス化して中圧酸素富化空気を得る第３間接熱交換工程と、
前記低圧酸素ガス又は前記低圧液化酸素を熱回収後に製品酸素ガスとして採取する製品ガス回収工程とを含む空気分離方法。 In the air separation method of collecting product oxygen by cryogenic liquefaction separation of raw material air,
A first separation step in which the compressed, purified and cooled raw material air is subjected to low-temperature distillation and separated into high-pressure nitrogen gas and high-pressure oxygen-enriched liquefied air;
A second separation step in which the high-pressure oxygen-enriched liquefied air is subjected to low-temperature distillation after decompression and separated into medium-pressure nitrogen gas and medium-pressure oxygen-enriched liquefied air;
The low-pressure oxygen-enriched liquefied air obtained by depressurizing the intermediate-pressure oxygen-enriched liquefied air and the intermediate-pressure nitrogen gas are indirectly heat exchanged to condense and liquefy the intermediate-pressure nitrogen gas to obtain the intermediate-pressure liquefied nitrogen and at the same time the low-pressure oxygen A first indirect heat exchange step of evaporating the enriched liquefied air to obtain low pressure oxygen enriched air;
A third separation step of low-temperature distillation of the low-pressure oxygen-enriched air to separate low-pressure nitrogen gas and low-pressure liquefied oxygen;
Second indirect heat to obtain low-pressure oxygen gas by evaporating and gasifying the low-pressure liquefied oxygen at the same time by condensing and liquefying the high-pressure nitrogen gas by indirect heat exchange between the high-pressure nitrogen gas and the low-pressure liquefied oxygen An exchange process;
The high-pressure nitrogen-enriched air produced in the intermediate stage of the first separation step and the intermediate-pressure oxygen-enriched liquefied air are indirectly heat-exchanged to condense and liquefy the high-pressure nitrogen-enriched air to obtain high-pressure nitrogen-enriched liquefied air. A third indirect heat exchange step of obtaining the intermediate pressure oxygen-enriched air by evaporating and gasifying the intermediate pressure oxygen-enriched liquefied air at the same time,
A product gas recovery step including collecting the low-pressure oxygen gas or the low-pressure liquefied oxygen as product oxygen gas after heat recovery. 原料空気を深冷液化分離して製品酸素を採取する空気分離方法において、
圧縮、精製、冷却した原料空気を低温蒸留して高圧窒素ガスと高圧酸素富化液化空気とに分離する第１分離工程と、
前記高圧酸素富化液化空気を減圧後に低温蒸留して中圧窒素ガスと中圧酸素富化液化空気とに分離する第２分離工程と、
前記中圧酸素富化液化空気を減圧した低圧酸素富化液化空気を低温蒸留して低圧窒素ガスと低圧液化酸素とに分離する第３分離工程と、
前記中圧窒素ガスと前記第３分離工程の中間段階の低圧酸素富化還流液化空気とを間接熱交換させて中圧窒素ガスを凝縮液化して中圧液化窒素を得ると同時に前記低圧酸素富化還流液化空気を蒸発ガス化して低圧酸素富化蒸発空気を得る第１間接熱交換工程と、
前記高圧窒素ガスと前記低圧液化酸素とを間接熱交換させて前記高圧窒素ガスを凝縮液化して高圧液化窒素を得ると同時に前記低圧液化酸素を蒸発ガス化して低圧酸素ガスを得る第２間接熱交換工程と、
前記第１分離工程の中間段階の高圧窒素富化空気と前記中圧酸素富化液化空気とを間接熱交換させて前記高圧窒素富化空気を凝縮液化して高圧窒素富化液化空気を得ると同時に前記中圧酸素富化液化空気を蒸発ガス化して中圧酸素富化空気を得る第３間接熱交換工程と、
前記低圧酸素ガス又は前記低圧液化酸素を熱回収後に製品酸素ガスとして採取する製品ガス回収工程とを含む空気分離方法。 In the air separation method of collecting product oxygen by cryogenic liquefaction separation of raw material air,
A first separation step in which the compressed, purified and cooled raw material air is subjected to low-temperature distillation and separated into high-pressure nitrogen gas and high-pressure oxygen-enriched liquefied air;
A second separation step in which the high-pressure oxygen-enriched liquefied air is subjected to low-temperature distillation after decompression and separated into medium-pressure nitrogen gas and medium-pressure oxygen-enriched liquefied air;
A third separation step in which the low-pressure oxygen-enriched liquefied air obtained by depressurizing the intermediate-pressure oxygen-enriched liquefied air is subjected to low-temperature distillation and separated into low-pressure nitrogen gas and low-pressure liquefied oxygen;
The intermediate-pressure nitrogen gas and the low-pressure oxygen-enriched reflux liquefied air in the intermediate stage of the third separation step are indirectly heat-exchanged to condense and liquefy the intermediate-pressure nitrogen gas to obtain intermediate-pressure liquefied nitrogen, and at the same time, the low-pressure oxygen-enriched A first indirect heat exchange step for evaporating gasified reflux liquefied air to obtain low-pressure oxygen-enriched evaporated air;
Second indirect heat to obtain low-pressure oxygen gas by evaporating and gasifying the low-pressure liquefied oxygen at the same time by condensing and liquefying the high-pressure nitrogen gas by indirect heat exchange between the high-pressure nitrogen gas and the low-pressure liquefied oxygen An exchange process;
When high-pressure nitrogen-enriched air in the intermediate stage of the first separation step and the intermediate-pressure oxygen-enriched liquefied air are indirectly heat exchanged to condense and liquefy the high-pressure nitrogen-enriched air to obtain high-pressure nitrogen-enriched liquefied air And a third indirect heat exchange step for simultaneously evaporating and gasifying the medium-pressure oxygen-enriched liquefied air to obtain medium-pressure oxygen-enriched air;
A product gas recovery step including collecting the low-pressure oxygen gas or the low-pressure liquefied oxygen as product oxygen gas after heat recovery. 前記第３間接熱交換工程は、熱交換型蒸留器の一方の通路に前記高圧窒素富化空気を上方向に流しながら凝縮液化して得られた液体を下方向に流す低温蒸留を行うことによって前記高圧窒素富化液化空気に加えてより窒素が濃縮した高圧低純窒素ガスを得ると同時に、前記熱交換型蒸留器の他方の通路に前記中圧酸素富化液化空気を下方向に流しながら蒸発ガス化して得られたガスを上方向に流す低温蒸留を行うことによって前記中圧酸素富化空気に加えてより酸素が濃縮した中圧低純液化酸素を得る請求項１又は２記載の空気分離方法。   The third indirect heat exchange step is performed by performing low-temperature distillation in which the liquid obtained by condensing and liquefying the high-pressure nitrogen-enriched air flows upward in one passage of the heat-exchange distiller. While obtaining high-pressure low-pure nitrogen gas in which nitrogen is further concentrated in addition to the high-pressure nitrogen-enriched liquefied air, the medium-pressure oxygen-enriched liquefied air is allowed to flow downward in the other passage of the heat exchange distiller. The air according to claim 1 or 2, wherein medium-pressure low-pure liquefied oxygen in which oxygen is further concentrated is obtained in addition to the medium-pressure oxygen-enriched air by performing low-temperature distillation in which a gas obtained by evaporative gasification flows upward. Separation method. 前記第３間接熱交換工程は、前記高圧窒素富化空気に代えて前記原料空気の一部を使用する請求項１乃至３のいずれか１項記載の空気分離方法。   The air separation method according to any one of claims 1 to 3, wherein the third indirect heat exchange step uses part of the raw material air instead of the high-pressure nitrogen-enriched air. 前記第１分離工程で得られた高圧窒素ガスを熱回収後に採取する高圧窒素ガス回収工程、前記第２分離工程で得られた中圧窒素ガスを熱回収後に採取する中圧窒素ガス回収工程、前記第３分離工程で得られた低圧窒素ガスを熱回収後に採取する低圧窒素ガス回収工程、前記第２間接熱交換工程で凝縮液化した前記高圧液化窒素を採取する高圧液化窒素回収工程、前記第１間接熱交換工程で凝縮液化した前記中圧液化窒素を採取する中圧液化窒素回収工程、及び、前記第３分離工程で得られた前記低圧液化酸素を回収する低圧液化酸素回収工程のうち少なくとも１つの工程を含む請求項１乃至４のいずれか１項記載の空気分離方法。   A high-pressure nitrogen gas recovery step for collecting the high-pressure nitrogen gas obtained in the first separation step after heat recovery, a medium-pressure nitrogen gas recovery step for collecting the medium-pressure nitrogen gas obtained in the second separation step after heat recovery, A low-pressure nitrogen gas recovery step in which the low-pressure nitrogen gas obtained in the third separation step is collected after heat recovery, a high-pressure liquefied nitrogen recovery step in which the high-pressure liquefied nitrogen condensed and liquefied in the second indirect heat exchange step is collected, At least one of the intermediate pressure liquefied nitrogen recovery step for collecting the intermediate pressure liquefied nitrogen condensed and liquefied in the indirect heat exchange step, and the low pressure liquefied oxygen recovery step for recovering the low pressure liquefied oxygen obtained in the third separation step. The air separation method according to any one of claims 1 to 4, comprising one step. 原料空気を深冷液化分離して製品酸素を採取する空気分離装置において、
圧縮、精製、冷却した原料空気を低温蒸留して高圧窒素ガスと高圧酸素富化液化空気とに分離する高圧塔と、
前記高圧酸素富化液化空気を減圧後に低温蒸留して中圧窒素ガスと中圧酸素富化液化空気とに分離する中圧塔と、
前記中圧酸素富化液化空気を減圧した低圧酸素富化液化空気と前記中圧窒素ガスとを間接熱交換させて中圧窒素ガスを凝縮液化して中圧液化窒素を得ると同時に前記低圧酸素富化液化空気を蒸発ガス化して低圧酸素富化空気を得る中圧塔凝縮器と、
前記低圧酸素富化空気を低温蒸留して低圧窒素ガスと低圧液化酸素とに分離する低圧塔と、
前記高圧窒素ガスと前記低圧液化酸素とを間接熱交換させて前記高圧窒素ガスを凝縮液化して高圧液化窒素を得ると同時に前記低圧液化酸素を蒸発ガス化して低圧酸素ガスを得る主凝縮蒸発器と、
前記高圧塔の中間部から抜き出した高圧窒素富化空気と前記中圧酸素富化液化空気とを間接熱交換させて前記高圧窒素富化空気を凝縮液化して高圧窒素富化液化空気を得ると同時に前記中圧酸素富化液化空気を蒸発ガス化して中圧酸素富化空気を得る中圧塔蒸化器と、前記低圧酸素ガス又は前記低圧液化酸素を熱回収後に製品酸素ガスとして採取する製品酸素ガス回収経路とを備えている空気分離装置。 In an air separation device that collects product oxygen by cryogenic liquefaction separation of raw material air,
A high-pressure column that separates the compressed, purified, and cooled raw material air into low-pressure distilled high-pressure nitrogen gas and high-pressure oxygen-enriched liquefied air;
An intermediate pressure tower for separating the high pressure oxygen-enriched liquefied air into an intermediate-pressure nitrogen gas and an intermediate-pressure oxygen-enriched liquefied air by low-temperature distillation after decompression;
The low-pressure oxygen-enriched liquefied air obtained by depressurizing the intermediate-pressure oxygen-enriched liquefied air and the intermediate-pressure nitrogen gas are indirectly heat exchanged to condense and liquefy the intermediate-pressure nitrogen gas to obtain the intermediate-pressure liquefied nitrogen and at the same time the low-pressure oxygen An intermediate pressure tower condenser for evaporating the enriched liquefied air to obtain low pressure oxygen enriched air;
A low-pressure column for separating the low-pressure oxygen-enriched air into low-pressure nitrogen gas and low-pressure liquefied oxygen by low-temperature distillation;
A main condensing evaporator that indirectly heat exchanges the high-pressure nitrogen gas and the low-pressure liquefied oxygen to condense and liquefy the high-pressure nitrogen gas to obtain high-pressure liquefied nitrogen, and at the same time evaporate and gasify the low-pressure liquefied oxygen to obtain low-pressure oxygen gas. When,
When high-pressure nitrogen-enriched air extracted from the middle part of the high-pressure column and the intermediate-pressure oxygen-enriched liquefied air are indirectly heat exchanged to condense and liquefy the high-pressure nitrogen-enriched air to obtain high-pressure nitrogen-enriched liquefied air At the same time, an intermediate pressure tower evaporator that evaporates and gasifies the medium pressure oxygen-enriched liquefied air, and a product that collects the low-pressure oxygen gas or the low-pressure liquefied oxygen as product oxygen gas after heat recovery An air separation device comprising an oxygen gas recovery path. 原料空気を深冷液化分離して製品酸素を採取する空気分離装置において、
圧縮、精製、冷却した原料空気を低温蒸留して高圧窒素ガスと高圧酸素富化液化空気とに分離する高圧塔と、
前記高圧酸素富化液化空気を減圧後に低温蒸留して中圧窒素ガスと中圧酸素富化液化空気とに分離する中圧塔と、
前記中圧酸素富化液化空気を減圧した低圧酸素富化液化空気を低温蒸留して低圧窒素ガスと低圧液化酸素とに分離する低圧塔と、
前記中圧窒素ガスと前記低圧塔の中間部を下降する低圧酸素富化還流液化空気とを間接熱交換させて中圧窒素ガスを凝縮液化して中圧液化窒素を得ると同時に前記低圧酸素富化還流液化空気を蒸発ガス化して低圧酸素富化蒸発空気を得る中圧窒素凝縮器と、
前記高圧窒素ガスと前記低圧液化酸素とを間接熱交換させて前記高圧窒素ガスを凝縮液化して高圧液化窒素を得ると同時に前記低圧液化酸素を蒸発ガス化して低圧酸素ガスを得る主凝縮蒸発器と、
前記高圧塔の中間部から抜き出した高圧窒素富化空気と前記中圧酸素富化液化空気とを間接熱交換させて前記高圧窒素富化空気を凝縮液化して高圧窒素富化液化空気を得ると同時に前記中圧酸素富化液化空気を蒸発ガス化して中圧酸素富化空気を得る中圧塔蒸化器と、前記低圧酸素ガス又は前記低圧液化酸素を熱回収後に製品酸素ガスとして採取する製品ガス回収経路とを備えている空気分離装置。 In an air separation device that collects product oxygen by cryogenic liquefaction separation of raw material air,
A high-pressure column that separates the compressed, purified, and cooled raw material air into low-pressure distilled high-pressure nitrogen gas and high-pressure oxygen-enriched liquefied air;
An intermediate pressure tower for separating the high pressure oxygen-enriched liquefied air into an intermediate-pressure nitrogen gas and an intermediate-pressure oxygen-enriched liquefied air by low-temperature distillation after decompression;
A low-pressure column for separating low-pressure nitrogen gas and low-pressure liquefied oxygen by low-temperature distillation of the low-pressure oxygen-enriched liquefied air obtained by depressurizing the medium-pressure oxygen-enriched liquefied air;
The intermediate-pressure nitrogen gas and the low-pressure oxygen-enriched reflux liquefied air descending the middle part of the low-pressure column are indirectly heat-exchanged to condense and liquefy the intermediate-pressure nitrogen gas to obtain intermediate-pressure liquefied nitrogen, and at the same time the low-pressure oxygen-enriched A medium-pressure nitrogen condenser that vaporizes the liquefied reflux liquefied air to obtain low-pressure oxygen-enriched evaporated air;
A main condensing evaporator that indirectly heat exchanges the high-pressure nitrogen gas and the low-pressure liquefied oxygen to condense and liquefy the high-pressure nitrogen gas to obtain high-pressure liquefied nitrogen, and at the same time evaporate and gasify the low-pressure liquefied oxygen to obtain low-pressure oxygen gas. When,
When high-pressure nitrogen-enriched air extracted from the middle part of the high-pressure column and the intermediate-pressure oxygen-enriched liquefied air are indirectly heat exchanged to condense and liquefy the high-pressure nitrogen-enriched air to obtain high-pressure nitrogen-enriched liquefied air At the same time, an intermediate pressure tower evaporator that evaporates and gasifies the medium pressure oxygen-enriched liquefied air, and a product that collects the low-pressure oxygen gas or the low-pressure liquefied oxygen as product oxygen gas after heat recovery An air separation device comprising a gas recovery path. 前記中圧塔蒸化器に代えて、一方の通路に前記高圧窒素富化空気の一部を上方向に流しながら凝縮液化して得られた液体を下方向に流す低温蒸留を行うことによって前記高圧窒素富化液化空気に加えてより窒素が濃縮した高圧低純窒素ガスを得ると同時に、他方の通路に前記中圧酸素富化液化空気を下方向に流しながら蒸発ガス化して得られたガスを上方向に流す低温蒸留を行うことによって前記中圧酸素富化空気に加えてより酸素が濃縮した中圧低純液化酸素を得る熱交換型蒸留器を用いる請求項６又は７記載の空気分離装置。   Instead of the intermediate-pressure tower evaporator, the low-temperature distillation is performed by flowing a liquid obtained by condensing and liquefying while flowing a part of the high-pressure nitrogen-enriched air upward in one passage. Gas obtained by evaporating gas while flowing the medium-pressure oxygen-enriched liquefied air downward in the other passage at the same time as obtaining high-pressure low-pure nitrogen gas enriched with nitrogen in addition to high-pressure nitrogen-enriched liquefied air The air separation according to claim 6 or 7, wherein a heat exchange type distiller is used to obtain medium-pressure low-pure liquefied oxygen in which oxygen is further concentrated in addition to the medium-pressure oxygen-enriched air by performing low-temperature distillation in which the gas flows upward. apparatus. 前記高圧窒素富化空気に代えて、前記原料空気の一部を使用する請求項６乃至８のいずれか１項記載の空気分離装置。   The air separation device according to any one of claims 6 to 8, wherein a part of the raw material air is used instead of the high-pressure nitrogen-enriched air. 前記高圧塔で得られた高圧窒素ガスを熱回収後に採取する高圧窒素ガス回収経路、前記中圧塔で得られた中圧窒素ガスを熱回収後に採取する中圧窒素ガス回収経路、前記低圧塔で得られた低圧窒素ガスを熱回収後に採取する低圧窒素ガス回収経路、前記主凝縮蒸発器で凝縮液化した前記高圧液化窒素を採取する高圧液化窒素回収経路、前記中圧塔凝縮器で凝縮液化した前記中圧液化窒素を採取する中圧液化窒素回収経路、前記低圧塔で得られた前記低圧液化酸素を回収する低圧液化酸素回収経路のうち少なくとも１つの経路を含む請求項６乃至９のいずれか１項記載の空気分離装置。   High-pressure nitrogen gas recovery path for collecting high-pressure nitrogen gas obtained in the high-pressure tower after heat recovery, Medium-pressure nitrogen gas recovery path for collecting medium-pressure nitrogen gas obtained in the medium-pressure tower after heat recovery, and the low-pressure tower Low-pressure nitrogen gas recovery path for collecting the low-pressure nitrogen gas obtained in step 1 after heat recovery, high-pressure liquefied nitrogen recovery path for collecting the high-pressure liquefied nitrogen condensed and liquefied by the main condensing evaporator, and condensing and liquefying by the medium-pressure tower condenser The medium pressure liquefied nitrogen recovery path for collecting the medium pressure liquefied nitrogen and the low pressure liquefied oxygen recovery path for recovering the low pressure liquefied oxygen obtained in the low pressure column are included. The air separation device according to claim 1.
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