JP4283521B2 - Gas liquefaction apparatus and method - Google Patents

Gas liquefaction apparatus and method Download PDF

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Publication number
JP4283521B2
JP4283521B2 JP2002296990A JP2002296990A JP4283521B2 JP 4283521 B2 JP4283521 B2 JP 4283521B2 JP 2002296990 A JP2002296990 A JP 2002296990A JP 2002296990 A JP2002296990 A JP 2002296990A JP 4283521 B2 JP4283521 B2 JP 4283521B2
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gas
liquid
phase
air
liquefied
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JP2004132602A (en
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俊幸 野島
哲史 須永
泰治 岸田
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Taiyo Nippon Sanso Corp
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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
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/0002—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the fluid to be liquefied
    • F25J1/0012—Primary atmospheric gases, e.g. 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
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/003—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production
    • F25J1/0032—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using the feed stream itself or separated fractions from it, i.e. "internal refrigeration"
    • F25J1/0035—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using the feed stream itself or separated fractions from it, i.e. "internal refrigeration" by gas expansion with extraction of work
    • F25J1/0037—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using the feed stream itself or separated fractions from it, i.e. "internal refrigeration" by gas expansion with extraction of work of a return stream
    • 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
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/003—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production
    • F25J1/0032—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using the feed stream itself or separated fractions from it, i.e. "internal refrigeration"
    • F25J1/004—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using the feed stream itself or separated fractions from it, i.e. "internal refrigeration" by flash gas recovery
    • 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
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/003—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production
    • F25J1/0032—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using the feed stream itself or separated fractions from it, i.e. "internal refrigeration"
    • F25J1/0045—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using the feed stream itself or separated fractions from it, i.e. "internal refrigeration" by vaporising a liquid return stream
    • 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
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/02—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process
    • F25J1/0201—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process using only internal refrigeration means, i.e. without external refrigeration
    • 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
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/02—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process
    • F25J1/0243—Start-up or control of the process; Details of the apparatus used; Details of the refrigerant compression system used
    • F25J1/0244—Operation; Control and regulation; Instrumentation
    • F25J1/0254—Operation; Control and regulation; Instrumentation controlling particular process parameter, e.g. pressure, temperature
    • F25J1/0255—Operation; Control and regulation; Instrumentation controlling particular process parameter, e.g. pressure, temperature controlling the composition of the feed or liquefied gas, e.g. to achieve a particular heating value of natural gas
    • 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
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/02—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process
    • F25J1/0243—Start-up or control of the process; Details of the apparatus used; Details of the refrigerant compression system used
    • F25J1/0244—Operation; Control and regulation; Instrumentation
    • F25J1/0256—Safety aspects of operation
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2245/00—Processes or apparatus involving steps for recycling of process streams
    • F25J2245/40—Processes or apparatus involving steps for recycling of process streams the recycled stream being air

Description

【０００１】
【発明の属する技術分野】
本発明は、ガス液化装置及び方法に関し、酸素を含有するガス、特に、空気（大気）を原料として液体空気を製造するのに適したガス液化装置及び方法に関する。
【０００２】
【従来の技術】
液化ガス、特に液化窒素は、希釈ガスやパージガスのバックアップ用ガス、各種物品の冷却用や凍結用の低温ガスとして広く用いられている。しかし、液化窒素は、精留塔を用いた空気液化分離装置で製造されており、設備コストが嵩むだけでなく、様々な用途に用いられるため、純度管理も厳密に行う必要がある。
【０００３】
一方、液化ガスを冷却用や凍結用として用いる場合は、その組成はほとんど問題にならない場合が多く、純度管理を行った液化窒素を用いる必要はなく、複雑な構造の精留塔を使用しない単純な構成のガス液化装置で空気（大気）を液化した液体空気を用いることが可能である。一般的なガス液化装置で液体空気を製造する場合、通常は、圧縮、精製、冷却した原料空気を液化ノズルから液体タンク内に噴出させて膨張させることにより原料空気の一部を液化し、液体タンク内に発生した液相を液体空気として使用するとともに、液体タンク内の気相を原料空気の冷却用に使用している（例えば、特許文献１参照。）。
【０００４】
【特許文献１】
特開平１０−２６４６９号公報（段落番号００１８、第３図）
【０００５】
【発明が解決しようとする課題】
ところが、空気を液化する場合、空気成分である酸素や窒素の揮発度の違いにより、液体タンクにおける液相と気相とで酸素濃度が異なり、液相（液体空気）における酸素濃度は３０％近くまで上昇してしまう。したがって、大気に比べて酸素濃度の高い液体空気となるため、例えば、これを圧縮する際には、酸素圧縮仕様の圧縮機を用いなければならないなど、酸素濃度に応じた安全性を考慮する必要がある。
【０００６】
そこで本発明は、空気のような酸素含有ガスを液化する際に、製品となる液化ガス中の酸素濃度を低くして安全性の高い酸素含有液化ガス、例えば酸素濃度が低い液体空気を製造することができるガス液化装置及び方法を提供することを目的としている。
【０００７】
【課題を解決するための手段】
上記目的を達成するため、本発明のガス液化装置は、酸素含有ガスを原料ガスとして液化ガスを製造するための装置であって、前記原料ガスを昇圧する圧縮機と、昇圧後の原料ガスをその圧力に応じた液化点まで冷却し、その一部を液化する熱交換器と、一部が液化した原料ガスを液相と気相とに分離する気液分離器と、分離後に気液分離器から導出した液相を減圧する減圧弁と、減圧後の液相と気液分離器から導出した前記気相とを熱交換させることにより気相を液化して前記原料ガスより酸素濃度の低い製品液化ガスを発生させるとともに前記減圧した液相を気化させる凝縮器とを備えていることを特徴としている。
【０００８】
また、本発明のガス液化方法は、酸素含有原料ガスを圧縮する工程と、圧縮した原料ガスをその圧力に応じた液化点まで冷却して一部を液化する工程と、一部が液化した原料ガスを気液分離する工程と、分離した液相を減圧する工程と、分離したガス相と前記減圧した液相とを熱交換させることにより前記ガス相を液化して前記原料ガスより酸素濃度の低い製品液化ガスを発生させるとともに前記減圧した液相を気化させる工程とを含むことを特徴としている。
【０００９】
さらに、本発明においては、前記原料ガスが空気（大気）であり、前記液化ガスが液体空気であることを特徴としている。なお、工場の各種設備や装置から排出された酸素含有排ガス、空気分離装置からの酸素含有排ガスを原料ガスとして用いることもできる。
【００１０】
【発明の実施の形態】
図１は本発明のガス液化装置の一形態例を示す系統図である。このガス液化装置は、酸素を含有した原料ガスを昇圧する圧縮機１１と、低温での閉塞が問題となる水分や二酸化炭素のような不純物を除去するための精製器１２と、昇圧後の原料ガスを冷却する熱交換器１３と、冷却されることによって一部が液化した原料ガスを気液分離する気液分離器１４と、気液分離器１４から導出した液相を減圧する減圧弁１５と、減圧後の液相と気液分離器１４から導出した気相とを熱交換させる凝縮器１６と、原料ガスの一部を断熱膨張させる膨張タービン１７と、これらを接続する経路とで形成されている。
【００１１】
まず、圧縮機１１で、例えば約６７０ｋＰａに圧縮された原料ガス、例えば原料空気は、冷却時に固化する水分や二酸化炭素等の不純物を精製器１２で除去された後、経路２１から熱交換器１３に導入されて排ガス等の低温ガスと熱交換を行い、その圧力に応じた液化点、例えば約−１７３℃まで冷却され、これによって原料空気の一部が液化した状態となる。
【００１２】
気液混合状態となった原料空気は、経路２２を通って気液分離器１４に導入され、気相Ｇと液相Ｌとに分離する。ここで、原料空気の主要組成を、窒素７８．１１％、酸素２０．９６％、アルゴン０．９３％としたとき、気液分離器１４内の気相Ｇの組成は、窒素８４．９１％、酸素１４．４０％、アルゴン０．６９％となり、液相Ｌの組成は、窒素７０．０４％、酸素２８．７２％、アルゴン１．２４％となる。なお、気相Ｇと液相Ｌとの生成割合は、原料空気の圧力及び冷却温度により異なる。
【００１３】
酸素濃度が高い液相Ｌは、気液分離器１４の下部から経路２３に導出され、減圧弁１５で大気圧付近まで減圧した後、経路２４を通って凝縮器１６の蒸発経路１６ａに冷却源として導入される。また、酸素濃度の低い気相Ｇは、気液分離器１４の上部から経路２５に導出され、経路２６を通って凝縮器１６の凝縮経路１６ｂに導入される。
【００１４】
この凝縮器１６において、蒸発経路１６ａを流れる減圧した後の液相と、凝縮経路１６ｂを流れる気相とが熱交換を行うことにより、気相が液化して液化ガス（製品液体空気ＬＡ）となり、凝縮器１６から経路２７を通って使用先あるいは貯蔵先に送られる。したがって、得られた製品液体空気ＬＡの酸素濃度は、気液分離器１４における気相Ｇの酸素濃度となり、この場合の酸素濃度は１４．４０％となる。
【００１５】
一方、前記減圧後の液相は、蒸発経路１６ａで気化することによって低温低圧の排ガスＷＧとなり、経路２８、２９を通って前記熱交換器１３に導入され、原料空気を冷却することによって昇温し、経路３０から系外に放出される。この排ガスＷＧの酸素濃度は、気液分離器１４における液相Ｌの酸素濃度と同じ２８．７２％であるが、そのまま大気に放出する分には全く問題はない。
【００１６】
また、前記経路２１から熱交換器１３に導入された前記原料空気の一部は、中温部で経路３１に分岐し、前記膨張タービン１７に導入されて大気圧付近まで断熱膨張することにより、装置の運転に必要な寒冷を発生する。膨張後の低温空気は、経路３２を通って前記経路２８からの排ガスＷＧと合流し、熱交換器１３を通って経路３０から系外に放出される。
【００１７】
さらに、製品液体空気製造量の変動や寒冷バランスの調整を行うため、例えば、前記凝縮器１６から製品液体空気ＬＡを取出す経路２７には、製品液体空気使用量の増減に対応させて液体空気の一部を気液分離器１４に戻すための経路４０を設けることもできる。
【００１８】
また、前記気液分離器１４から気相Ｇを導出する経路２５には、気相Ｇの一部を分岐する経路４１が設けられている。この経路４１に分岐した気相Ｇは、そのまま熱交換器１３に導入して原料空気を冷却した後、経路４２から高圧の排ガスＷＨとして放出してもよく、図１に破線で示す経路４２を設けてタービン流体の一部として寒冷発生用に使用することもできる。
【００１９】
このようにして原料空気（原料ガス）に比べて酸素濃度の低い液体空気（液化ガス）を製造することができるため、大気よりも酸素濃度が高いガスを原料ガスとして使用しても、大気組成と同程度以下の酸素濃度を有する液化ガス（液体空気）を製造することが可能である。
【００２０】
例えば、窒素製造用の空気分離装置からは、酸素濃度が高い排ガス、例えば酸素濃度４０％程度の排ガスが排出されるが、この排ガスを原料ガスとして用いた場合でも、酸素圧縮仕様の圧縮機を用いるなどの考慮を必要としない酸素濃度、一般的には２５％以下の酸素濃度の液化ガス、特に酸素濃度が約２１％以下の安全な液体空気を得ることができる。
【００２１】
このような空気分離装置の排ガスを原料ガスとして用いる場合、通常は、空気分離装置が備えている吸着器等で水分や二酸化炭素等の不純物が除去されているため、原料ガス中の不純物を再度除去する必要がなくなるので、前述の精製器１２は省略することが可能である。また、原料ガスとして使用する排ガスの圧力が十分に高い場合、例えば、空気分離装置における運転圧力が高くて排ガスの圧力も高い場合は、前述の圧縮機１１を省略することも可能である。さらに、系外からの寒冷源を利用できるときは、前述の膨張タービン１７を省略することもできる。
【００２２】
このようなガス液化装置で、前述のような液体空気を製造する場合、装置構成が簡単で、安全な液体空気が得られるため、冷却や凍結を行う設備に隣接配置することが可能となり、運搬や貯蔵に対する考慮も軽減できる。
【００２３】
【発明の効果】
以上説明したように、本発明によれば、酸素濃度の低い安全な液体空気を簡単な機器構成の装置で安価に発生させることができる。したがって、従来は高価な液化窒素を使用していた冷却設備や凍結設備における運転コストの低減を図ることができる。
【図面の簡単な説明】
【図１】 本発明のガス液化装置の一形態例を示す系統図である。
【符号の説明】
１１…圧縮機、１２…精製器、１３…熱交換器、１４…気液分離器、１５…減圧弁、１６…凝縮器、１７…膨張タービン、ＬＡ…製品液体空気[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a gas liquefaction apparatus and method, and more particularly to a gas liquefaction apparatus and method suitable for producing liquid air using oxygen-containing gas, in particular, air (atmosphere) as a raw material.
[0002]
[Prior art]
A liquefied gas, particularly liquefied nitrogen, is widely used as a backup gas for a dilution gas and a purge gas, and as a low-temperature gas for cooling and freezing various articles. However, liquefied nitrogen is produced by an air liquefaction separation apparatus using a rectifying column, which not only increases the equipment cost, but also is used for various applications, so that it is necessary to strictly manage the purity.
[0003]
On the other hand, when the liquefied gas is used for cooling or freezing, its composition is hardly a problem, and it is not necessary to use liquefied nitrogen whose purity is controlled, and it is not necessary to use a rectifying column having a complicated structure. It is possible to use liquid air obtained by liquefying air (atmosphere) with a gas liquefying apparatus having such a structure. When liquid air is produced by a general gas liquefaction device, normally, a portion of the raw material air is liquefied by injecting the compressed, purified, and cooled raw material air into a liquid tank from a liquefying nozzle and expanding the liquid air. The liquid phase generated in the tank is used as liquid air, and the gas phase in the liquid tank is used for cooling the raw material air (see, for example, Patent Document 1).
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 10-26469 (paragraph number 0018, FIG. 3)
[0005]
[Problems to be solved by the invention]
However, when air is liquefied, the oxygen concentration differs between the liquid phase and the gas phase in the liquid tank due to the volatility of oxygen and nitrogen, which are air components, and the oxygen concentration in the liquid phase (liquid air) is close to 30%. Will rise to. Therefore, since it becomes liquid air with a higher oxygen concentration than the atmosphere, for example, when compressing this, it is necessary to consider safety according to the oxygen concentration, such as using a compressor with an oxygen compression specification. There is.
[0006]
Therefore, the present invention produces a highly safe oxygen-containing liquefied gas, for example, liquid air having a low oxygen concentration, by reducing the oxygen concentration in the liquefied gas as a product when liquefying an oxygen-containing gas such as air. It is an object of the present invention to provide a gas liquefaction apparatus and method that can be used.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, a gas liquefaction apparatus according to the present invention is an apparatus for producing a liquefied gas using an oxygen-containing gas as a source gas, the compressor for boosting the source gas, and a source gas after being boosted. cooled to liquefaction point corresponding to its pressure, a heat exchanger to liquefy a part of the gas-liquid separator for separating a feed gas part is liquefied into a liquid phase and a gas phase, gas-liquid separation after separation A pressure reducing valve for depressurizing the liquid phase derived from the vessel, and the liquid phase after depressurization and the gas phase derived from the gas-liquid separator are heat-exchanged to liquefy the gas phase and have a lower oxygen concentration than the source gas And a condenser that generates a product liquefied gas and vaporizes the reduced liquid phase.
[0008]
The gas liquefaction method of the present invention includes a step of compressing an oxygen-containing source gas, a step of cooling the compressed source gas to a liquefaction point corresponding to the pressure, and a part of the liquefaction source, and a partially liquefied source material A step of gas-liquid separation of the gas, a step of depressurizing the separated liquid phase, and heat-exchanging the separated gas phase and the decompressed liquid phase to liquefy the gas phase and to reduce oxygen concentration from the source gas. And a step of generating a low product liquefied gas and vaporizing the reduced liquid phase.
[0009]
Further, the present invention is characterized in that the source gas is air (atmosphere) and the liquefied gas is liquid air. In addition, the oxygen-containing exhaust gas discharged | emitted from the various facilities and apparatuses of a factory, and the oxygen-containing exhaust gas from an air separation apparatus can also be used as raw material gas.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a system diagram showing an embodiment of the gas liquefying apparatus of the present invention. This gas liquefaction apparatus includes a compressor 11 that pressurizes a raw material gas containing oxygen, a purifier 12 that removes impurities such as moisture and carbon dioxide that are obstructed at a low temperature, and a raw material after pressurization. A heat exchanger 13 that cools the gas, a gas-liquid separator 14 that gas-liquid separates the source gas partially liquefied by cooling, and a pressure-reducing valve 15 that decompresses the liquid phase derived from the gas-liquid separator 14 And a condenser 16 for exchanging heat between the liquid phase after decompression and the gas phase derived from the gas-liquid separator 14, an expansion turbine 17 for adiabatically expanding a part of the raw material gas, and a path connecting them. Has been.
[0011]
First, the raw material gas, for example, raw material air, compressed by the compressor 11 to about 670 kPa, for example, is removed from the purifier 12 by impurities such as moisture and carbon dioxide that are solidified at the time of cooling. And is exchanged with a low-temperature gas such as exhaust gas, and cooled to a liquefaction point corresponding to the pressure, for example, about −173 ° C., whereby a part of the raw material air is liquefied.
[0012]
The raw material air in a gas-liquid mixed state is introduced into the gas-liquid separator 14 through the path 22 and separated into a gas phase G and a liquid phase L. Here, when the main composition of the raw material air is 78.11% nitrogen, 20.96% oxygen, and 0.93% argon, the composition of the gas phase G in the gas-liquid separator 14 is 84.91% nitrogen. 14.40% oxygen and 0.69% argon, and the composition of the liquid phase L is 70.04% nitrogen, 28.72% oxygen, and 1.24% argon. In addition, the production | generation ratio of the gaseous phase G and the liquid phase L changes with the pressure and cooling temperature of raw material air.
[0013]
The liquid phase L having a high oxygen concentration is led out from the lower part of the gas-liquid separator 14 to the path 23, and is decompressed to near atmospheric pressure by the pressure reducing valve 15, and then passes through the path 24 to the evaporation path 16 a of the condenser 16. As introduced. Further, the gas phase G having a low oxygen concentration is led out from the upper part of the gas-liquid separator 14 to the path 25, and is introduced into the condensation path 16 b of the condenser 16 through the path 26.
[0014]
In this condenser 16, the liquid phase after depressurization flowing through the evaporation path 16a and the gas phase flowing through the condensation path 16b exchange heat, whereby the gas phase is liquefied to become liquefied gas (product liquid air LA). , And sent from the condenser 16 through the path 27 to a use place or a storage place. Therefore, the oxygen concentration of the product liquid air LA obtained is the oxygen concentration of the gas phase G in the gas-liquid separator 14, and the oxygen concentration in this case is 14.40%.
[0015]
On the other hand, the liquid phase after depressurization becomes low-temperature and low-pressure exhaust gas WG by being vaporized in the evaporation path 16a, and is introduced into the heat exchanger 13 through the paths 28 and 29, and the temperature is raised by cooling the raw air. Then, it is discharged out of the system from the route 30. The oxygen concentration of the exhaust gas WG is 28.72%, which is the same as the oxygen concentration of the liquid phase L in the gas-liquid separator 14, but there is no problem with the amount released to the atmosphere as it is.
[0016]
In addition, a part of the raw air introduced from the path 21 to the heat exchanger 13 branches into the path 31 at the intermediate temperature part, and is introduced into the expansion turbine 17 and adiabatically expanded to near atmospheric pressure, thereby the apparatus. Generates the cold necessary for driving. The expanded low-temperature air merges with the exhaust gas WG from the path 28 through the path 32 and is discharged from the path 30 through the heat exchanger 13 to the outside of the system.
[0017]
Furthermore, in order to adjust the fluctuation of the product liquid air production amount and the cold balance, for example, in the path 27 for taking out the product liquid air LA from the condenser 16, the liquid air flow is adjusted in accordance with the increase or decrease in the amount of product liquid air used. A path 40 for returning a part to the gas-liquid separator 14 can also be provided.
[0018]
A path 41 for branching a part of the gas phase G is provided in the path 25 for deriving the gas phase G from the gas-liquid separator 14. The gas phase G branched into the path 41 may be introduced into the heat exchanger 13 as it is to cool the raw air, and then discharged from the path 42 as high-pressure exhaust gas WH. The path 42 indicated by a broken line in FIG. It can also be used for generating cold as part of the turbine fluid.
[0019]
Since liquid air (liquefied gas) having a lower oxygen concentration than raw material air (raw material gas) can be produced in this way, even if a gas having a higher oxygen concentration than the atmosphere is used as the raw material gas, the atmospheric composition It is possible to produce a liquefied gas (liquid air) having an oxygen concentration equal to or less than the above.
[0020]
For example, an air separation device for producing nitrogen emits exhaust gas with a high oxygen concentration, for example, exhaust gas with an oxygen concentration of about 40%. Even when this exhaust gas is used as a raw material gas, a compressor with oxygen compression specifications is used. It is possible to obtain a liquefied gas having an oxygen concentration that does not require consideration such as use, generally 25% or less, particularly safe liquid air having an oxygen concentration of about 21% or less.
[0021]
When using the exhaust gas of such an air separation device as a raw material gas, since impurities such as moisture and carbon dioxide are usually removed by an adsorber provided in the air separation device, the impurities in the raw material gas are removed again. The purifier 12 described above can be omitted because it is not necessary to remove it. Further, when the pressure of the exhaust gas used as the raw material gas is sufficiently high, for example, when the operating pressure in the air separation device is high and the pressure of the exhaust gas is high, the above-described compressor 11 can be omitted. Furthermore, when a cold source from outside the system can be used, the aforementioned expansion turbine 17 can be omitted.
[0022]
When liquid air as described above is produced with such a gas liquefaction device, the device configuration is simple and safe liquid air can be obtained, so that it can be placed adjacent to a facility for cooling and freezing and transported. And storage considerations can be reduced.
[0023]
【The invention's effect】
As described above, according to the present invention, safe liquid air having a low oxygen concentration can be generated at low cost with an apparatus having a simple device configuration. Therefore, it is possible to reduce the operating cost in the cooling facility and the freezing facility that conventionally used expensive liquefied nitrogen.
[Brief description of the drawings]
FIG. 1 is a system diagram showing an embodiment of a gas liquefying apparatus according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Compressor, 12 ... Purifier, 13 ... Heat exchanger, 14 ... Gas-liquid separator, 15 ... Pressure reducing valve, 16 ... Condenser, 17 ... Expansion turbine, LA ... Product liquid air

Claims (4)

酸素含有ガスを原料ガスとして液化ガスを製造するための装置であって、前記原料ガスを昇圧する圧縮機と、昇圧後の原料ガスをその圧力に応じた液化点まで冷却し、その一部を液化する熱交換器と、一部が液化した原料ガスを液相と気相とに分離する気液分離器と、分離後に気液分離器から導出した液相を減圧する減圧弁と、減圧後の液相と気液分離器から導出した前記気相とを熱交換させることにより気相を液化して前記原料ガスより酸素濃度の低い製品液化ガスを発生させるとともに前記減圧した液相を気化させる凝縮器とを備えていることを特徴とするガス液化装置。An apparatus for producing a liquefied gas using an oxygen-containing gas as a source gas, the compressor for boosting the source gas, and cooling the source gas after the pressurization to a liquefaction point corresponding to the pressure, and a part thereof a heat exchanger to liquefy a gas-liquid separator for separating a feed gas part is liquefied into a liquid phase and a gas phase, a pressure reducing valve for reducing the pressure of the liquid phase derived from gas-liquid separator after the separation, after depressurization The liquid phase and the gas phase derived from the gas-liquid separator are heat-exchanged to liquefy the gas phase to generate a product liquefied gas having a lower oxygen concentration than the source gas, and to vaporize the reduced liquid phase A gas liquefying apparatus comprising a condenser. 前記原料ガスが空気であり、前記液化ガスが液体空気であることを特徴とする請求項１記載のガス液化装置。  The gas liquefying apparatus according to claim 1, wherein the source gas is air and the liquefied gas is liquid air. 酸素含有原料ガスを圧縮する工程と、圧縮した原料ガスをその圧力に応じた液化点まで冷却して一部を液化する工程と、一部が液化した原料ガスを気液分離する工程と、分離した液相を減圧する工程と、分離したガス相と前記減圧した液相とを熱交換させることにより前記ガス相を液化して前記原料ガスより酸素濃度の低い製品液化ガスを発生させるとともに前記減圧した液相を気化させる工程とを含むことを特徴とするガス液化方法。A step of compressing the oxygen-containing source gas, a step of cooling the compressed source gas to a liquefaction point corresponding to the pressure, partially liquefying, a step of gas-liquid separation of the partially liquefied source gas, and a separation Reducing the pressure of the liquid phase, and heat-exchanging the separated gas phase and the pressure-reduced liquid phase to liquefy the gas phase to generate a product liquefied gas having a lower oxygen concentration than the source gas, and to reduce the pressure And a step of vaporizing the liquid phase. 前記原料ガスが空気であり、前記液化ガスが液体空気であることを特徴とする請求項３記載のガス液化方法。  4. The gas liquefaction method according to claim 3, wherein the source gas is air and the liquefied gas is liquid air.
JP2002296990A 2002-10-10 2002-10-10 Gas liquefaction apparatus and method Expired - Fee Related JP4283521B2 (en)

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