JP4142559B2 - Gas liquefaction apparatus and gas liquefaction method - Google Patents
Gas liquefaction apparatus and gas liquefaction method Download PDFInfo
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- 238000000034 method Methods 0.000 title claims description 30
- 239000007789 gas Substances 0.000 claims description 140
- 239000007788 liquid Substances 0.000 claims description 89
- 239000003949 liquefied natural gas Substances 0.000 claims description 67
- 238000001816 cooling Methods 0.000 claims description 10
- 239000012530 fluid Substances 0.000 claims description 7
- 238000010438 heat treatment Methods 0.000 claims description 6
- 238000000926 separation method Methods 0.000 claims description 5
- 238000007599 discharging Methods 0.000 claims description 3
- 238000010792 warming Methods 0.000 claims description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 22
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 20
- 230000006835 compression Effects 0.000 description 13
- 238000007906 compression Methods 0.000 description 13
- 239000003345 natural gas Substances 0.000 description 11
- 229910001873 dinitrogen Inorganic materials 0.000 description 10
- 238000010248 power generation Methods 0.000 description 9
- 238000004880 explosion Methods 0.000 description 7
- 229910052757 nitrogen Inorganic materials 0.000 description 5
- 230000007423 decrease Effects 0.000 description 3
- 230000003247 decreasing effect Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000001704 evaporation Methods 0.000 description 2
- 229910052786 argon Inorganic materials 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 239000011555 saturated liquid Substances 0.000 description 1
- 230000008961 swelling Effects 0.000 description 1
- 238000011144 upstream manufacturing Methods 0.000 description 1
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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
- F25J1/003—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
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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
- F25J1/0015—Nitrogen
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- 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
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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
- F25J1/02—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
- F25J1/0221—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 the cold stored in an external cryogenic component in an open refrigeration loop
- F25J1/0224—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 the cold stored in an external cryogenic component in an open refrigeration loop in combination with an internal quasi-closed refrigeration loop
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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
- F25J1/02—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
- F25J1/0257—Construction and layout of liquefaction equipments, e.g. valves, machines
- F25J1/0262—Details of the cold heat exchange system
- F25J1/0264—Arrangement of heat exchanger cores in parallel with different functions, e.g. different cooling streams
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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
- F25J2210/00—Processes characterised by the type or other details of the feed stream
- F25J2210/06—Splitting of the feed stream, e.g. for treating or cooling in different ways
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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
- F25J2210/00—Processes characterised by the type or other details of the feed stream
- F25J2210/62—Liquefied natural gas [LNG]; Natural gas liquids [NGL]; Liquefied petroleum gas [LPG]
Description
本発明は、液化天然ガス（ＬＮＧ）の寒冷を利用したガスの液化方法およびガスの液化装置に関し、特に空気分離装置などによって製造される窒素ガスの液化技術として有用である。 The present invention relates to a gas liquefaction method and gas liquefaction apparatus using liquefied natural gas (LNG) cooling, and is particularly useful as a liquefaction technique for nitrogen gas produced by an air separation apparatus or the like.
天然ガス（ＮＧ）は、輸送や貯蔵の利便性などのため、液化天然ガス（ＬＮＧ）として貯蔵され、これを気化した後に、主として火力発電用や都市ガス用として用いられる。このため、ＬＮＧの寒冷を有効利用する技術が開発されている。 Natural gas (NG) is stored as liquefied natural gas (LNG) for convenience of transportation and storage, and after being vaporized, it is mainly used for thermal power generation and city gas. For this reason, a technique for effectively utilizing the coldness of LNG has been developed.
ＬＮＧの寒冷を利用して窒素ガス等を液化する設備としては、一般に、窒素ガスを圧縮機でＬＮＧとの熱交換で液化可能な圧力まで圧縮し、次いで熱交換器でＬＮＧと熱交換させてＬＮＧを昇温気化させるとともに、窒素ガスを液化するプロセスが用いられている。 As equipment for liquefying nitrogen gas etc. using the coldness of LNG, in general, nitrogen gas is compressed to a pressure that can be liquefied by heat exchange with LNG with a compressor, and then heat exchanged with LNG with a heat exchanger. A process of evaporating LNG at a temperature and liquefying nitrogen gas is used.
しかしながら、火力発電や都市ガスは、１日のうち、昼に需要が多く、夜に需要が少ないという需要の変動がある。従って、上記のガス液化プロセスに供給されるＬＮＧ量も、上記需要変動によって変動するため、利用できる寒冷量も変動してしまう。このため、供給されるＬＮＧ量が多いときは上記ガス液化プロセスで得られる液化ガス量を増大できるが、ＬＮＧ量が減少すれば液化ガス量も減少することになる。 However, there is a fluctuation in demand for thermal power generation and city gas, where demand is high during the day and demand is low at night. Therefore, since the amount of LNG supplied to the gas liquefaction process also fluctuates due to the fluctuation in demand, the amount of cold that can be used also fluctuates. For this reason, when the amount of LNG supplied is large, the amount of liquefied gas obtained by the gas liquefaction process can be increased. However, when the amount of LNG decreases, the amount of liquefied gas also decreases.
一方、圧縮機を駆動するための電力は、昼間の料金に比べて夜間が安く設定されているため、上記ＬＮＧの供給量の変動と電力料金の差を勘案して、効率よくガスを液化するためのガス液化プロセスが提案されている。例えば、１台以上のガス用圧縮機と、１台以上のガス用膨張タービンと、ガスと液化天然ガスとを熱交換させる熱交換器とを備えた液化プロセスにより、前記液化天然ガスの寒冷を利用して前記ガスを液化する方法において、供給される液化天然ガスの増量時には前記膨張タービンを停止又は減量運転し、供給される液化天然ガスの減量時には前記膨張タービンを稼働又は増量運転することを特徴とする液化天然ガスの寒冷を利用したガスの液化方法が知られている（例えば、特許文献１参照）。 On the other hand, the electric power for driving the compressor is set to be cheaper at night than the charge during the daytime, so the gas is efficiently liquefied taking into consideration the fluctuation in the supply amount of the LNG and the difference in the power charge. A gas liquefaction process has been proposed. For example, the liquefied natural gas is cooled by a liquefaction process including one or more gas compressors, one or more gas expansion turbines, and a heat exchanger that exchanges heat between the gas and liquefied natural gas. In the method of liquefying the gas, the expansion turbine is stopped or reduced when the supplied liquefied natural gas is increased, and the expansion turbine is operated or increased when the supplied liquefied natural gas is reduced. A gas liquefaction method using the chilling of liquefied natural gas, which is a feature, is known (see, for example, Patent Document 1).
しかしながら、上記の液化方法では、膨張タービンで発生した寒冷を有する低温ガスが熱交換器に導入される際に、低温ガスが別に導入される液化天然ガス（一般に１ＭＰａ以上である）より低圧になる。このため、もし熱交換器にリークが発生した場合、天然ガスが液化するガスのラインに混入し、爆発の危険性があった。なお、ガス用圧縮機で圧縮後に熱交換器と減圧弁とを経たガス成分も、液化天然ガスより低圧にて熱交換器に導入される。 However, in the above liquefaction method, when the low-temperature gas having cold generated in the expansion turbine is introduced into the heat exchanger, the pressure becomes lower than that of liquefied natural gas (generally 1 MPa or more) into which the low-temperature gas is separately introduced. . For this reason, if a leak occurs in the heat exchanger, natural gas is mixed into the liquefied gas line and there is a risk of explosion. In addition, the gas component which passed through the heat exchanger and the pressure-reducing valve after being compressed by the gas compressor is also introduced into the heat exchanger at a lower pressure than liquefied natural gas.
一方、窒素ガスを液化する際に、多段階に圧縮しつつ複数の熱交換器でＬＮＧで冷却するガスの液化方法が知られている（例えば、特許文献２参照）。しかし、この液化方法でも、熱交換器に導入するＬＮＧの圧力が、導入するガスの圧力より高くなり、上述した爆発の危険性が残る。また、熱交換器で冷却後の低温ガスを圧縮するため、低温圧縮機が必要となり、断続的な運転には適さないので、昼夜で変動するＬＮＧ量に対応して、液化プロセスを断続的に行うことは困難であった。つまり、低温圧縮機を使用する場合、その冷却のための準備工程や電力費用が必要となり、断続的な運転を行うと工程時間や費用のロスが大きくなる。 On the other hand, there is known a gas liquefaction method in which nitrogen gas is liquefied and cooled by LNG with a plurality of heat exchangers while being compressed in multiple stages (see, for example, Patent Document 2). However, even in this liquefaction method, the pressure of LNG introduced into the heat exchanger becomes higher than the pressure of the introduced gas, and the above-described explosion risk remains. In addition, since the low temperature gas after cooling is compressed by the heat exchanger, a low temperature compressor is necessary and is not suitable for intermittent operation. Therefore, the liquefaction process is intermittently adapted to the amount of LNG that fluctuates day and night. It was difficult to do. That is, when a low-temperature compressor is used, a preparation process for cooling and power costs are necessary, and intermittent operation increases process time and cost loss.
更に、特許文献２に記載のガスの液化方法では、低温ガスの一段の膨張後、気液分離器で気化成分のみをＬＮＧ熱交換器に戻す方式が取られており、後ほど議論する如く、効率的な運転ができない。
そこで、本発明の目的は、天然ガスのリークによる爆発の危険性を回避することができ、また、昼夜で変動するＬＮＧ量に対応して断続的な運転が好適に行え、更に多段階の圧縮・膨張によって効率的なガスの液化を行うことができるガスの液化方法及びガスの液化装置を提供することにある。 Accordingly, the object of the present invention is to avoid the danger of explosion due to natural gas leaks, and to perform intermittent operation suitably in response to the amount of LNG varying between day and night, and further to multistage compression. An object of the present invention is to provide a gas liquefaction method and a gas liquefaction apparatus capable of performing efficient gas liquefaction by expansion.
上記目的は、下記の如き本発明により達成できる。 The above object can be achieved by the present invention as described below.
即ち、本発明のガスの液化方法は、複数段からなる圧縮機で圧縮されたガスの主要部を第１熱交換器に導入して液化天然ガスと熱交換させながら低温ガスとし、導出した低温ガスの一部を前記液化天然ガスより高い圧力の範囲で膨張させた後に、再び前記第１熱交換器に戻して熱交換により自身を加温した後、前記圧縮機の適切な圧力の中間段に合流させると共に、前記第１熱交換器から導出した低温ガスの残部を膨張させて更に低温に冷却して第１気液分離器に導入し、前記圧縮機で圧縮されたガスの残部を第２熱交換器に導入して熱交換により自身を冷却してから膨張させて更に低温に冷却して前記第１気液分離器に導入し、その第１気液分離器で集合された気体は再び前記第２熱交換器に戻して熱交換により自身を加温した後、前記圧縮機の適切な圧力の中間段又は吸入段に合流させながら、前記第１気液分離器で集合された液体を取り出す工程を含み、かつ前記第１熱交換器に導入された液化天然ガスの一部を、前記第１熱交換器の中間部から液化天然ガスの状態で分岐・排出し、残部を第１熱交換器から気体状態で導出することを特徴とする。 That is, in the gas liquefaction method of the present invention, the main part of the gas compressed by the multi-stage compressor is introduced into the first heat exchanger to make a low temperature gas while exchanging heat with the liquefied natural gas. After expanding a part of the gas in a range of pressure higher than that of the liquefied natural gas, it is returned to the first heat exchanger and heated by heat exchange, and then an intermediate stage of an appropriate pressure of the compressor. And the remaining portion of the low-temperature gas derived from the first heat exchanger is expanded and further cooled to a low temperature and introduced into the first gas-liquid separator. The remaining portion of the gas compressed by the compressor is 2 It introduces into the heat exchanger, cools itself by heat exchange, expands, cools to a lower temperature, introduces it into the first gas-liquid separator, and the gas collected in the first gas-liquid separator is After returning to the second heat exchanger again and heating itself by heat exchange, While merging the suitable pressure intermediate stage or inhalation stage of the machine, said step of removing a is set liquid in the first gas-liquid separator seen including, and the liquefied natural gas introduced into the first heat exchanger A part is branched and discharged from the intermediate part of the first heat exchanger in the form of liquefied natural gas, and the remaining part is led out from the first heat exchanger in a gaseous state .
本発明のガスの液化方法によると、熱交換により自身を加温したガスを圧縮機の入口側に合流させているため、圧縮機として低温圧縮機を使用する必要がなく、断続的な運転が可能となる。また、第１熱交換器から導出したガスを分岐して、その一部を液化天然ガスより高い圧力の範囲で膨張させた後に、再び第１熱交換器に導入するため、第１熱交換器にリークが生じても、窒素等の圧力の方が高いため、天然ガスが漏れ込むことなく爆発の危険性を回避することができる。更に、多段階の圧縮・膨張によって効率的なガスの液化を行うことができるのは、次の理由による。 According to the gas liquefaction method of the present invention, since the gas heated by heat exchange is joined to the inlet side of the compressor, there is no need to use a low-temperature compressor as the compressor, and intermittent operation is possible. It becomes possible. In addition, since the gas derived from the first heat exchanger is branched and a part thereof is expanded in a range of pressure higher than that of the liquefied natural gas, the first heat exchanger is introduced again into the first heat exchanger. Even if a leak occurs, the pressure of nitrogen or the like is higher, so that the danger of an explosion can be avoided without the natural gas leaking. Furthermore, the reason why gas can be efficiently liquefied by multi-stage compression / expansion is as follows.
窒素ガスなどの液化にＬＮＧの寒冷を利用するとき、ＬＮＧの温度は−１５５℃前後であり、一方窒素の大気圧沸点は−１９６℃であるので、この間の温度レベルの差を埋める必要がある。そのため、窒素ガスを通常臨界圧力以上（好ましくは５〜６ＭＰａ）に昇圧してから、ＬＮＧの寒冷を利用して約−１５３℃まで冷却し、これを自由膨張し、低温を得る方法が知られている。膨張後の圧力を低くすればするほど低温が得られるが、膨張により生じる気体成分の割合は増え、正味液化量は減少する。またその気体成分を再利用するために、再度圧縮する必要があり、その圧縮比の増加つれ所要動力も増加する。そのため、膨張の圧力を如何に選定するか、また何段階で膨張するかによって液化に要する圧縮動力が変化する。 When using LNG cold for liquefaction of nitrogen gas etc., the temperature of LNG is around −155 ° C., while the atmospheric pressure boiling point of nitrogen is −196 ° C., so it is necessary to fill in the temperature level difference between them. . For this reason, a method is known in which the nitrogen gas is usually boosted to a critical pressure or higher (preferably 5 to 6 MPa) and then cooled to about −153 ° C. using the coldness of LNG, which is freely expanded to obtain a low temperature. ing. The lower the pressure after expansion, the lower the temperature is obtained, but the proportion of the gas component generated by expansion increases and the net liquefaction amount decreases. Further, in order to reuse the gaseous component, it is necessary to compress again, and the required power increases as the compression ratio increases. Therefore, the compression power required for liquefaction varies depending on how the expansion pressure is selected and in what stage the expansion is performed.
また、利用できるＬＮＧ量に対して液化量要求量が多いと窒素の低温域の液化のための寒冷が特に不足してくる。これを解消するために、ＬＮＧで冷却した低温ガスの一部を膨張して戻すことが有効である。この場合には、再度圧縮の圧縮比が小さく、僅かな動力の増加に限定でき、有効である。このため本発明では、多段の膨張を組み合わせることにより、効率的な運転が可能となる。ここで、第１熱交換器の中間段から分岐・排出した液化天然ガスは、液化するガスの量に応じて増減量することができるとともに、蒸発させてから、発電等に使用することができる。また、第１熱交換器から気体状態で導出された天然ガスは、発電等に使用することができる。従って、こうした液化天然ガスを寒冷として利用したガスの液化操作は、発電や都市ガスの需要に応じて実施することができ、昼夜で変動するＬＮＧ量に対応して断続的な運転が好適に行うことができる。 In addition, when the required amount of liquefaction is larger than the amount of LNG that can be used, cooling for liquefaction of nitrogen in a low temperature region is particularly insufficient. In order to solve this problem, it is effective to expand and return part of the low-temperature gas cooled by LNG. In this case, the compression ratio of compression is small again, and it can be limited to a slight increase in power, which is effective. For this reason, in this invention, efficient driving | operation is attained by combining multistage expansion | swelling. Here, the liquefied natural gas branched and discharged from the intermediate stage of the first heat exchanger can be increased or decreased according to the amount of the gas to be liquefied, and can be used for power generation after being evaporated. . Moreover, the natural gas derived | led-out in the gaseous state from the 1st heat exchanger can be used for an electric power generation. Therefore, the gas liquefaction operation using such liquefied natural gas as a cold can be performed according to the demand for power generation and city gas, and intermittent operation is suitably performed corresponding to the amount of LNG changing day and night. be able to.
上記の結果、天然ガスのリークによる爆発の危険性を回避することができ、また、昼夜で変動するＬＮＧ量に対応して断続的な運転が好適に行え、更に多段階の圧縮・膨張によって効率的なガスの液化を行うことができるガスの液化方法を提供できる。 As a result of the above, the risk of explosion due to natural gas leaks can be avoided, and intermittent operation can be suitably performed in response to the amount of LNG changing day and night, and more efficient by multistage compression and expansion. It is possible to provide a gas liquefaction method capable of performing gas liquefaction.
上記において、前記第１気液分離器から取り出された液体を更に少なくとも１段膨張させて更に低温にして第２気液分離器に導入し、膨張で生成した気体分を再び第２熱交換器に戻して熱交換により自身を加温した後、前記圧縮機の適切な圧力の中間段又は吸入段に合流させながら、前記第２気液分離器の液体を取り出す工程を更に含むことが好ましい。 In the above, the liquid taken out from the first gas-liquid separator is further expanded at least one stage, further cooled to be introduced into the second gas-liquid separator, and the gas generated by the expansion is again supplied to the second heat exchanger. It is preferable that the method further includes a step of taking out the liquid of the second gas-liquid separator while joining itself to an intermediate stage or a suction stage of an appropriate pressure of the compressor after heating itself by heat exchange.
この場合、第１気液分離器から取り出した液体を膨張させて一部を気化することによって、その膨張時の冷却効果によって、より低温で大気圧に近い液化ガスを得ることができる。また、第２気液分離器からガス分を導出して第２熱交換器に導入して自身を加温した後に前記圧縮機の適切な圧力の中間段又は吸入段に合流させることで、低温のガス分によって、第２熱交換器に導入されるガスを更に冷却することができる。 In this case, the liquid taken out from the first gas-liquid separator is expanded and partially vaporized, whereby a liquefied gas close to atmospheric pressure can be obtained at a lower temperature due to the cooling effect during the expansion. In addition, the gas component is derived from the second gas-liquid separator, introduced into the second heat exchanger and heated, and then joined to the intermediate stage or the suction stage of an appropriate pressure of the compressor. By this gas component, the gas introduced into the second heat exchanger can be further cooled.
一方、本発明のガスの液化装置は、複数段からなる圧縮機と、その圧縮機で圧縮されたガスの主要部を導入して液化天然ガスと熱交換させる第１熱交換器と、その第１熱交換器から導出したガスの一部を前記液化天然ガスより高い圧力の範囲で膨張させる第１膨張弁と、その第１膨張弁を経たガスを前記第１熱交換器に導入して熱交換後に前記圧縮機の適切な圧力の中間段に合流させる経路と、前記第１熱交換器から導出したガスの残部を膨張させて更に低温に冷却する第２膨張弁と、その第２膨張弁を経た流体を導入する第１気液分離器と、その第１気液分離器から導出したガス分と前記圧縮機で圧縮されたガスの残部とを熱交換する第２熱交換器と、前記第１気液分離器から導出したガス分を前記第２熱交換器に導入した後に前記圧縮機の適切な圧力の中間段又は吸入段に合流させる経路と、前記圧縮機で圧縮されたガスの残部を第２熱交換器に導入した後に第３膨張弁を経て前記第１気液分離器に導入する経路と、前記第１気液分離器から液化した液体を取り出す経路とを備え、かつ前記第１熱交換器に導入された液化天然ガスの一部を前記第１熱交換器の中間部から液化天然ガスの状態で分岐・排出する経路と、残部を第１熱交換器から気体状態で導出する経路とを備えることを特徴とする。 On the other hand, the gas liquefaction apparatus of the present invention includes a multi-stage compressor, a first heat exchanger that introduces a main part of the gas compressed by the compressor and exchanges heat with liquefied natural gas, and a first heat exchanger thereof. A first expansion valve that expands a part of the gas derived from one heat exchanger in a range of pressure higher than that of the liquefied natural gas, and a gas that has passed through the first expansion valve are introduced into the first heat exchanger to generate heat. A path for joining the intermediate stage of the compressor with an appropriate pressure after the exchange, a second expansion valve for expanding the remaining gas derived from the first heat exchanger and cooling it to a lower temperature, and the second expansion valve A first gas-liquid separator that introduces the fluid having passed through the second gas exchanger, a second heat exchanger that exchanges heat between the gas component derived from the first gas-liquid separator and the remainder of the gas compressed by the compressor, After the gas component derived from the first gas-liquid separator is introduced into the second heat exchanger, the compressor A path for joining an intermediate stage or a suction stage having an appropriate pressure, and the remainder of the gas compressed by the compressor are introduced into the second heat exchanger and then introduced into the first gas-liquid separator through a third expansion valve. And a path for taking out the liquefied liquid from the first gas-liquid separator , and a part of the liquefied natural gas introduced into the first heat exchanger from an intermediate part of the first heat exchanger It comprises a path for branching and discharging in the state of liquefied natural gas and a path for deriving the remainder from the first heat exchanger in a gaseous state .
本発明のガスの液化装置によると、熱交換により自身を加温したガスを圧縮機の入口側に合流させているため、圧縮機として低温圧縮機を使用する必要がなく、断続的な運転が可能となる。また、第１熱交換器から導出したガスを分岐して、第１膨張弁によってその一部を液化天然ガスより高い圧力の範囲で膨張させた後に、再び第１熱交換器に導入するため、第１熱交換器にリークが生じても、窒素等の圧力の方が高いため、天然ガスが漏れ込むことなく爆発の危険性を回避することができる。さらに、第１熱交換器の中間段から分岐・排出した液化天然ガスは、液化するガスの量に応じて増減量することができるとともに、蒸発させてから、発電等に使用することができる。また、第１熱交換器から気体状態で導出された天然ガスは、発電等に使用することができる。また、更に、上述した理由から、多段階の圧縮・膨張によって効率的なガスの液化を行うことができる。その結果、天然ガスのリークによる爆発の危険性を回避することができ、また、昼夜で変動するＬＮＧ量に対応して断続的な運転が好適に行え、更に多段階の圧縮・膨張によって効率的なガスの液化を行うことができるガスの液化装置を提供できる。 According to the gas liquefaction apparatus of the present invention, since the gas heated by heat exchange is joined to the inlet side of the compressor, there is no need to use a low-temperature compressor as the compressor, and intermittent operation is possible. It becomes possible. In addition, in order to branch the gas derived from the first heat exchanger and expand a part thereof in a range of pressure higher than that of liquefied natural gas by the first expansion valve, the gas is again introduced into the first heat exchanger. Even if a leak occurs in the first heat exchanger, since the pressure of nitrogen or the like is higher, the risk of explosion can be avoided without the natural gas leaking. Furthermore, the liquefied natural gas branched and discharged from the intermediate stage of the first heat exchanger can be increased or decreased according to the amount of gas to be liquefied, and can be used for power generation or the like after being evaporated. Moreover, the natural gas derived | led-out in the gaseous state from the 1st heat exchanger can be used for an electric power generation. Furthermore, for the reasons described above, efficient gas liquefaction can be performed by multistage compression / expansion. As a result, the risk of explosion due to natural gas leaks can be avoided, and intermittent operation can be suitably performed corresponding to the amount of LNG changing day and night, and more efficient by multi-stage compression and expansion. It is possible to provide a gas liquefying apparatus capable of liquefying various gases.
上記において、前記第１気液分離器から取り出した液体を更に少なくとも１段膨張させて更に低温に冷却する第４膨張弁と、その第４膨張弁を経た流体を導入する第２気液分離器と、その第２気液分離器からガス分を導出して第２熱交換器に導入して自身を加温した後に前記圧縮機の適切な圧力の中間段又は吸入段に合流させる経路と、前記第２気液分離器の液体を取り出す経路とを更に備えることが好ましい。 In the above, the fourth expansion valve that further expands the liquid taken out from the first gas-liquid separator at least one stage and cools it to a lower temperature, and the second gas-liquid separator that introduces the fluid that has passed through the fourth expansion valve And a path for deriving a gas component from the second gas-liquid separator, introducing it into the second heat exchanger and warming itself, and then joining the intermediate stage or the suction stage with an appropriate pressure of the compressor; It is preferable to further include a path for taking out the liquid of the second gas-liquid separator.
この場合、第１気液分離器から取り出した液体を、第４膨張弁で膨張させて一部を気化することによって、その膨張時の冷却効果によって、より低温で大気圧に近い液化ガスを得ることができる。また、第２気液分離器からガス分を導出して第２熱交換器に導入して自身を加温した後に前記圧縮機の適切な圧力の中間段又は吸入段に合流させることで、低温のガス分によって、第２熱交換器に導入されるガスを更に冷却することができる。 In this case, the liquid taken out from the first gas-liquid separator is expanded by the fourth expansion valve to partially vaporize, thereby obtaining a liquefied gas at a lower temperature and close to atmospheric pressure due to the cooling effect during the expansion. be able to. In addition, the gas component is derived from the second gas-liquid separator, introduced into the second heat exchanger and heated, and then joined to the intermediate stage or the suction stage of an appropriate pressure of the compressor. By this gas component, the gas introduced into the second heat exchanger can be further cooled.
以下、本発明の実施の形態について、図面を参照しながら説明する。図１は、本発明のガスの液化装置の一例を示す概略構成図である。なお、本実施形態では、液化するガスとして窒素ガスの場合を例示するが、本発明は、他のガス、例えば空気やアルゴン等の液化にも同様にして適用することができる。また、各部の温度、圧力、流量などの条件は、ガスの種類や流量等、その他の条件に応じて適宜変更することができる。 Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an example of a gas liquefying apparatus according to the present invention. In the present embodiment, the case of nitrogen gas is exemplified as the gas to be liquefied, but the present invention can be similarly applied to liquefaction of other gases such as air and argon. Moreover, conditions, such as temperature of each part, a pressure, and a flow volume, can be suitably changed according to other conditions, such as a kind and flow volume of gas.
本発明のガスの液化装置は、複数段からなる圧縮機を備える。本実施形態では、図１に示すように、上流側より低圧段の圧縮機Ｃ１、中圧段の圧縮機Ｃ２、及び高圧段の圧縮機Ｃ３の３個の圧縮機を備える例を示す。 The gas liquefying apparatus of the present invention includes a compressor composed of a plurality of stages. In the present embodiment, as shown in FIG. 1, an example in which three compressors, that is, a low-pressure stage compressor C1, an intermediate-pressure stage compressor C2, and a high-pressure stage compressor C3 are provided from the upstream side.
本発明では、低圧段の圧縮機Ｃ１に、液化の対象となるガス（例えば窒素ガス（ＧＮ2 ））が導入される。このガスは常温（２５℃）より低温でもよいが、常温付近の方が低温圧縮機の使用を避けられるため好ましい。また、本発明では、圧縮機Ｃ１〜Ｃ３の入口側に、熱交換で加温されたガスが合流するため、何れの圧縮機Ｃ１〜Ｃ３も低温圧縮機の使用を避けることができる。本実施形態では、例えば、常温で大気圧付近の窒素ガスを圧縮機Ｃ１に導入（３４０００Ｎｍ3 ／ｈ）して約０．４ＭＰａ（ゲージ圧、以下同じ）まで圧縮し、次いで圧縮機Ｃ２により約３ＭＰａまで圧縮し、次いで圧縮機Ｃ３により約５ＭＰａまで圧縮する。本発明では、最終的に圧縮機Ｃ３により５〜６ＭＰａまで圧縮するのが好ましい。 In the present invention, a gas to be liquefied (for example, nitrogen gas (GN 2 )) is introduced into the low-pressure stage compressor C1. This gas may be at a temperature lower than room temperature (25 ° C.), but a temperature near room temperature is preferable because the use of a low-temperature compressor can be avoided. Moreover, in this invention, since the gas heated by heat exchange joins to the inlet side of compressor C1-C3, any compressor C1-C3 can avoid use of a low-temperature compressor. In the present embodiment, for example, nitrogen gas at normal temperature and near atmospheric pressure is introduced into the compressor C1 (34000 Nm 3 / h) and compressed to about 0.4 MPa (gauge pressure, the same applies hereinafter), and then the compressor C2 performs about Compress to 3 MPa, then compress to about 5 MPa with compressor C3. In this invention, it is preferable to finally compress to 5-6 MPa with the compressor C3.
この圧縮ガスの主要部は、第１熱交換器Ｅ１に導入され、向流に導入される液化天然ガス（ＬＮＧ）と熱交換して冷却される。本実施形態では、第１熱交換器Ｅ１が、２つの熱交換器Ｅ１ａと熱交換器Ｅ１ｂとで構成される例を示す。液化天然ガスは熱交換器Ｅ１ｂに、例えば約１．９ＭＰａ、−１５５℃、４５トン／ｈで導入され、熱交換器Ｅ１ｂから導出された後、一部が余剰寒冷として液化天然ガスの状態で分岐・排出され、残部が熱交換器Ｅ１ａに導入される。 The main part of this compressed gas is introduced into the first heat exchanger E1, and is cooled by exchanging heat with liquefied natural gas (LNG) introduced into the counterflow. In this embodiment, the 1st heat exchanger E1 shows the example comprised by two heat exchanger E1a and heat exchanger E1b. The liquefied natural gas is introduced into the heat exchanger E1b at, for example, about 1.9 MPa, −155 ° C. and 45 ton / h, and after being led out from the heat exchanger E1b, a part thereof is in the state of liquefied natural gas as excessive cold. It is branched and discharged, and the remainder is introduced into the heat exchanger E1a.
熱交換器Ｅ１ａで気体状態で導出された天然ガスは、約１．９ＭＰａで常温付近であり、発電等に使用することができる。また、分岐・排出した液化天然ガスも、蒸発させてから、同様に利用することができる。一般に、火力発電や都市ガスは、１日のうち、昼に需要が多く、夜に需要が少ないため、本発明では、昼間時間帯のみガスの液化方法を実施して、断続的な運転を行うことができる。なお、液化天然ガスの分岐・排出は、液化するガスの量に応じて、増減量することができる。 Natural gas derived in a gas state by the heat exchanger E1a is about 1.9 MPa and is near room temperature, and can be used for power generation and the like. Further, the liquefied natural gas branched and discharged can be used in the same manner after evaporating. In general, thermal power generation and city gas have a high demand at daytime during the day and a low demand at night. Therefore, in the present invention, the gas liquefaction method is performed only during the daytime period to perform intermittent operation. be able to. The branching / exhaust of liquefied natural gas can be increased or decreased according to the amount of gas to be liquefied.
圧縮ガスは、第１熱交換器Ｅ１で液化天然ガス（ＬＮＧ）と熱交換されて、約−１５３℃まで冷却される。第１熱交換器Ｅ１（熱交換器Ｅ１ｂ）から導出した低温ガスの一部（約８０００Ｎｍ3 ／ｈ）は第１膨張弁Ｖ１に導入され、熱交換器Ｅ１ｂに導入される液化天然ガスより高い圧力の範囲（例えば約３ＭＰａ）に膨張させる。この膨張は自由膨張に相当し、寒冷を発生させる。 The compressed gas is heat-exchanged with liquefied natural gas (LNG) in the first heat exchanger E1 and cooled to about −153 ° C. Part of the low temperature gas (about 8000 Nm 3 / h) derived from the first heat exchanger E1 (heat exchanger E1b) is introduced into the first expansion valve V1, and is higher than the liquefied natural gas introduced into the heat exchanger E1b. The pressure is expanded to a range (for example, about 3 MPa). This expansion corresponds to free expansion and generates cold.
第１膨張弁Ｖ１を経たガスは、第１熱交換器Ｅ１に導入して熱交換した後に、複数段の圧縮機の適切な圧力の中間段に合流させる。本実施形態では、高圧段の圧縮機Ｃ３の入口側に合流させる例を示す。このとき、第１熱交換器Ｅ１に導入されたガスは、自身が常温付記まで加温されると共に、圧縮機Ｃ３からのガスを冷却する。 The gas that has passed through the first expansion valve V1 is introduced into the first heat exchanger E1 for heat exchange, and then merged with an intermediate stage having an appropriate pressure in a plurality of stages of compressors. In the present embodiment, an example is shown in which the high-pressure stage compressor C3 is joined to the inlet side. At this time, the gas introduced into the first heat exchanger E1 is heated to the normal temperature addition and cools the gas from the compressor C3.
一方、第１熱交換器Ｅ１から導出したガスの残部は第２膨張弁Ｖ２に導入（約２６０００Ｎｍ3 ／ｈ）され、これを膨張させて更に低温に冷却する、この膨張は自由膨張に相当し、寒冷を発生させると共に、ガスの一部を液化することができる。膨張後の圧力は、本例では０．４ＭＰａである。 On the other hand, the remainder of the gas derived from the first heat exchanger E1 is introduced into the second expansion valve V2 (about 26000 Nm 3 / h), and is expanded to cool to a lower temperature. This expansion corresponds to free expansion. In addition to generating cold, part of the gas can be liquefied. The pressure after expansion is 0.4 MPa in this example.
膨張後の流体は、第１気液分離器Ｂ１に導入され、気液分離される。液化した液体は第１気液分離器Ｂ１の底部に連結した経路から取り出される。この液分は、約１７４００Ｎｍ3 ／ｈである。 The fluid after expansion is introduced into the first gas-liquid separator B1, and gas-liquid separation is performed. The liquefied liquid is taken out from the path connected to the bottom of the first gas-liquid separator B1. This liquid content is about 17400 Nm 3 / h.
また、第１気液分離器Ｂ１から導出したガス分は、第２熱交換器Ｅ２に導入（約８６００Ｎｍ3 ／ｈ）され、高圧段の圧縮機Ｃ３の出口側から分岐し向流にて導入（約４４００Ｎｍ3 ／ｈ）される残部ガスと熱交換される。これによって、圧縮機Ｃ３からの残部ガスは、−１７５℃まで冷却される。 The gas component derived from the first gas-liquid separator B1 is introduced into the second heat exchanger E2 (approximately 8600 Nm 3 / h), branched from the outlet side of the high-pressure stage compressor C3, and introduced in a countercurrent manner. Heat exchange with the remaining gas (about 4400 Nm 3 / h). As a result, the remaining gas from the compressor C3 is cooled to -175 ° C.
第１気液分離器Ｂ１から導出したガス分は、第２熱交換器Ｅ２に導入した後、複数段の圧縮機の適切な圧力の中間段又は吸入段に合流させる。本実施形態では、中圧段の圧縮機Ｃ２の入口側に合流させる例を示す。また、高圧段の圧縮機Ｃ３の出口側から分岐したガスは第２熱交換器Ｅ２に導入した後、第３膨張弁Ｖ３を経て第１気液分離器Ｂ１に導入される。 The gas component derived from the first gas-liquid separator B1 is introduced into the second heat exchanger E2, and then merged into an intermediate stage or an intake stage having an appropriate pressure of a plurality of compressors. In the present embodiment, an example is shown in which the medium is joined to the inlet side of the compressor C2 in the intermediate pressure stage. Further, the gas branched from the outlet side of the high-pressure stage compressor C3 is introduced into the second heat exchanger E2, and then introduced into the first gas-liquid separator B1 through the third expansion valve V3.
第３膨張弁Ｖ３では、約５ＭＰａで導入されたガスが、約０．４ＭＰａまで膨張（自由膨張）され、更に低温に冷却され、これによって飽和状態で一部が液化される。ガス分（２００Ｎｍ3 ／ｈ）と液分（４２００Ｎｍ3 ／ｈ）は、第２膨張弁Ｖ２を経た流体と混合され、混合物として第１気液分離器Ｂ１から、各々導出される。 In the third expansion valve V3, the gas introduced at about 5 MPa is expanded (free expansion) to about 0.4 MPa, further cooled to a low temperature, and thereby partially liquefied in a saturated state. The gas component (200 Nm 3 / h) and the liquid component (4200 Nm 3 / h) are mixed with the fluid that has passed through the second expansion valve V2, and are respectively derived from the first gas-liquid separator B1 as a mixture.
本実施形態では、図２に示すように、第１気液分離器Ｂ１から取り出した液体を更に膨張させて更に低温に冷却する例を示す。つまり、第１気液分離器Ｂ１から取り出した液体は、第４膨張弁Ｖ４に導入され、０．０３ＭＰａまで膨張（自由膨張）されて一部が気化される。このとき、液分１８０００Ｎｍ3 ／ｈとガス分３６００Ｎｍ3 ／ｈとが生じ、これらが第２気液分離器Ｂ２に導入される。 In this embodiment, as shown in FIG. 2, the liquid taken out from 1st gas-liquid separator B1 is expanded further, and the example cooled further to low temperature is shown. That is, the liquid taken out from the first gas-liquid separator B1 is introduced into the fourth expansion valve V4 and expanded (free expansion) to 0.03 MPa, and a part thereof is vaporized. At this time, a liquid content of 18000 Nm 3 / h and a gas content of 3600 Nm 3 / h are generated, and these are introduced into the second gas-liquid separator B2.
第２気液分離器Ｂ２からは、ガス分が導出されて、第２熱交換器Ｅ２に導入される。このとき、導入されたガス分は、高圧段の圧縮機Ｃ３の出口側からのガスを冷却して自身は加温される。第２熱交換器Ｅ２から導出されたガス分は、複数段の圧縮機の適切な圧力の中間段又は吸入段に合流させるが、本例では低圧段の圧縮機Ｃ１の入口側に合流される。 A gas component is derived from the second gas-liquid separator B2 and introduced into the second heat exchanger E2. At this time, the introduced gas is heated by cooling the gas from the outlet side of the high-pressure compressor C3. The gas components derived from the second heat exchanger E2 are joined to the intermediate stage or the suction stage having an appropriate pressure of a plurality of stages of compressors. In this example, they are joined to the inlet side of the low-pressure stage compressor C1. .
第２気液分離器Ｂ２の底部からは、液化した液体（ＬＮ2 ）が１８０００Ｎｍ3 ／ｈ、約０．０３ＭＰａ、約−１９４℃にて取り出される。 From the bottom of the second gas-liquid separator B2, liquefied liquid (LN 2 ) is taken out at 18000 Nm 3 / h, about 0.03 MPa, and about −194 ° C.
本発明のガスの液化方法は、以上のように、複数段からなる圧縮機Ｃ１〜Ｃ３で圧縮されたガスの主要部を第１熱交換器Ｅ１に導入して液化天然ガスと熱交換させながら低温ガスとし、導出した低温ガスの一部を前記液化天然ガスより高い圧力の範囲で膨張させた後に、再び前記第１熱交換器Ｅ１に戻して熱交換により自身を加温した後、前記圧縮機Ｃ１〜Ｃ３の適切な圧力の中間段に合流させると共に、前記第１熱交換器Ｅ１から導出した低温ガスの残部を膨張させて更に低温に冷却して第１気液分離器Ｂ１に導入し、前記圧縮機Ｃ１〜Ｃ３で圧縮されたガスの残部を第２熱交換器Ｅ２に導入して熱交換により自身を冷却してから膨張させて更に低温に冷却して前記第１気液分離器Ｂ１に導入し、その第１気液分離器Ｂ１で集合された気体は再び前記第２熱交換器Ｅ２に戻して熱交換により自身を加温した後、前記圧縮機Ｃ１〜Ｃ３の適切な圧力の中間段又は吸入段に合流させながら、前記第１気液分離器Ｂ１で集合された液体を取り出す工程を含むものである。 In the gas liquefaction method of the present invention, as described above, the main part of the gas compressed by the multistage compressors C1 to C3 is introduced into the first heat exchanger E1 to exchange heat with the liquefied natural gas. After a part of the derived low-temperature gas is expanded in a range of pressure higher than that of the liquefied natural gas, it is returned to the first heat exchanger E1 and heated by heat exchange, and then compressed. And the remaining low-temperature gas derived from the first heat exchanger E1 is expanded and cooled to a lower temperature and introduced into the first gas-liquid separator B1. The remaining part of the gas compressed by the compressors C1 to C3 is introduced into the second heat exchanger E2, cooled by itself through heat exchange, expanded and then cooled to a lower temperature, and then the first gas-liquid separator. Gas introduced into B1 and collected in the first gas-liquid separator B1 After returning to the second heat exchanger E2 and heating itself by heat exchange, the first gas-liquid separator B1 is joined to the intermediate stage or the suction stage of the compressors C1 to C3 at an appropriate pressure. And a step of taking out the liquid collected in step (b).
本実施形態では、前記第１気液分離器Ｂ１から取り出された液体を更に少なくとも１段膨張させて更に低温にして第２気液分離器Ｂ２に導入し、膨張で生成した気体分を再び第２熱交換器Ｅ２に戻して熱交換により自身を加温した後、前記圧縮機Ｃ１〜Ｃ３の適切な圧力の中間段又は吸入段に合流させながら、前記第２気液分離器Ｂ２の液体を取り出す工程を更に含む例を示した。 In the present embodiment, the liquid taken out from the first gas-liquid separator B1 is further expanded at least one stage to be further cooled to be introduced into the second gas-liquid separator B2, and the gas component generated by the expansion is again supplied to the first gas-liquid separator B1. 2 After returning to the heat exchanger E2 and heating itself by heat exchange, the liquid in the second gas-liquid separator B2 is added to the intermediate stage or the suction stage at an appropriate pressure of the compressors C1 to C3. The example further including the process of taking out was shown.
本例で示した運転条件によると、約０．０３ＭＰａの飽和液体窒素を得るための液化原単位は０．２８３ｋＷｈ／Ｎｍ3 となる。この値は、膨張タービンを用いた（ＬＮＧ不使用）従来の液化方法の液化原単位０．６〜０．７ｋＷｈ／Ｎｍ3 と比較して、大幅な動力の低減となる。 According to the operating conditions shown in this example, the liquefaction unit for obtaining saturated liquid nitrogen of about 0.03 MPa is 0.283 kWh / Nm 3 . This value is a significant reduction in power as compared with the liquefaction unit 0.6 to 0.7 kWh / Nm 3 of the conventional liquefaction method using an expansion turbine (without LNG).
［他の実施形態］
（１）前述の実施形態では、３段の圧縮機を設けて、３種の膨張圧に応じた、圧縮・熱交換・膨張からなる循環経路を設ける例を示したが、本発明では、更に多段の圧縮機を設けて、更に多段の膨張圧に応じた、圧縮・熱交換・膨張からなる循環経路を設けるようにしてもよい。
[Other Embodiments]
(1) In the above-described embodiment, an example in which a three-stage compressor is provided and a circulation path including compression, heat exchange, and expansion according to three types of expansion pressures is provided. A multistage compressor may be provided, and a circulation path composed of compression, heat exchange, and expansion may be provided according to the multistage expansion pressure.
その場合、第２気液分離器から取り出した液体を膨張させて一部を気化する第５膨張弁と、その第５膨張弁を経た流体を導入する第３気液分離器と、その第３気液分離器からガス分を導出して第３熱交換器に導入して自身を加温した後に第ｎ−３段目の圧縮機の入口側に合流させる経路と、前記第３気液分離器から液化した液体を取り出す経路とを備えるガスの液化装置となる。 In that case, a fifth expansion valve that expands the liquid taken out from the second gas-liquid separator to partially vaporize, a third gas-liquid separator that introduces the fluid that has passed through the fifth expansion valve, and a third thereof A gas component derived from the gas-liquid separator, introduced into the third heat exchanger and heated, and then joined to the inlet side of the n-3rd stage compressor; and the third gas-liquid separation The gas liquefying apparatus includes a path for taking out the liquefied liquid from the vessel.
（２）前述の実施形態では、３段の圧縮機を各々設ける例を示したが、１台の圧縮装置で複数段に圧縮を行うようにしてもよく、更に多段の圧縮を行ってもよい。また、３段の圧縮機のそれぞれの中間に戻りガスを合流させているが、戻りガスの合流は、圧縮機の適切な圧力の中間段に対して行えばよい。 (2) In the above-described embodiment, an example in which each of the three-stage compressors is provided has been described. However, the compression may be performed in a plurality of stages by a single compression device, or may be further performed in multiple stages. . In addition, the return gas is joined to the middle of each of the three-stage compressors, but the return gas may be joined to the intermediate stage having an appropriate pressure of the compressor.
Ｅ１ 第１熱交換器
Ｅ２ 第２熱交換器
Ｃ１ 圧縮機（低圧段）
Ｃ２ 圧縮機（中圧段）
Ｃ３ 圧縮機（高圧段）
Ｖ１ 第１膨張弁
Ｖ２ 第２膨張弁
Ｖ３ 第３膨張弁
Ｖ４ 第４膨張弁
Ｂ１ 第１気液分離器
Ｂ２ 第２気液分離器
E1 1st heat exchanger E2 2nd heat exchanger C1 Compressor (low pressure stage)
C2 compressor (medium pressure stage)
C3 compressor (high pressure stage)
V1 1st expansion valve V2 2nd expansion valve V3 3rd expansion valve V4 4th expansion valve B1 1st gas-liquid separator B2 2nd gas-liquid separator
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| KR20150106868A (en) * | 2015-09-04 | 2015-09-22 | 현대중공업 주식회사 | Treatment system of liquefied gas |
| KR101643038B1 (en) * | 2013-11-29 | 2016-07-26 | 현대중공업 주식회사 | A Treatment System of Liquefied Gas |
| KR20210036826A (en) | 2019-09-26 | 2021-04-05 | 레르 리키드 쏘시에떼 아노님 뿌르 레뜌드 에렉스뿔라따시옹 데 프로세데 조르즈 클로드 | Gas liquefaction apparatus |
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| KR101278587B1 (en) | 2012-05-22 | 2013-06-25 | 연세대학교 산학협력단 | Liquefaction method of natural gas for energy reduction |
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| KR101643038B1 (en) * | 2013-11-29 | 2016-07-26 | 현대중공업 주식회사 | A Treatment System of Liquefied Gas |
| KR20150106868A (en) * | 2015-09-04 | 2015-09-22 | 현대중공업 주식회사 | Treatment system of liquefied gas |
| KR102053479B1 (en) * | 2015-09-04 | 2019-12-10 | 현대중공업 주식회사 | Treatment system of liquefied gas |
| KR20210036826A (en) | 2019-09-26 | 2021-04-05 | 레르 리키드 쏘시에떼 아노님 뿌르 레뜌드 에렉스뿔라따시옹 데 프로세데 조르즈 클로드 | Gas liquefaction apparatus |
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