JP2007255802A - Cryogenic gas separation system - Google Patents

Cryogenic gas separation system Download PDF

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Publication number
JP2007255802A
JP2007255802A JP2006081849A JP2006081849A JP2007255802A JP 2007255802 A JP2007255802 A JP 2007255802A JP 2006081849 A JP2006081849 A JP 2006081849A JP 2006081849 A JP2006081849 A JP 2006081849A JP 2007255802 A JP2007255802 A JP 2007255802A
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heat exchanger
raw material
total heat
air
separation system
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Taku Nasu
卓 那須
Hitoshi Ishizuka
仁司 石塚
Kanetoshi Hayashi
謙年 林
Kenjiro Hamada
謙二郎 浜田
Toshihiko Kukutsu
寿彦 久々津
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JFE Steel Corp
JFE Engineering Corp
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JFE Steel Corp
JFE Engineering 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
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
    • F25J3/04006—Providing pressurised feed air or process streams within or from the air fractionation unit
    • F25J3/04012—Providing pressurised feed air or process streams within or from the air fractionation unit by compression of warm gaseous streams; details of intake or interstage cooling
    • F25J3/04018—Providing pressurised feed air or process streams within or from the air fractionation unit by compression of warm gaseous streams; details of intake or interstage cooling of main feed 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
    • F25J3/04406—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air using a dual pressure main column system
    • F25J3/04412—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air using a dual pressure main column system in a classical double column flowsheet, i.e. with thermal coupling by a main reboiler-condenser in the bottom of low pressure respectively top of high pressure column
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2245/00—Processes or apparatus involving steps for recycling of process streams
    • F25J2245/42—Processes or apparatus involving steps for recycling of process streams the recycled stream being nitrogen

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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

<P>PROBLEM TO BE SOLVED: To provide a cryogenic gas separation system capable of efficiently recovering low-temperature exhaust heat from excess waste nitrogen to further reduce power of a compressor compressing a raw material gas, in the cryogenic gas separation system for compressing, refining and cooling the air, and introducing the air into a rectifying tower, to manufacture oxygen or nitrogen by performing liquefaction, rectification and separation. <P>SOLUTION: A rotary total heat exchanger 21 for exchanging heat between the raw material gas and waste nitrogen, is disposed on an inlet of the raw material air compressor 12. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

本発明は、空気を圧縮、精製、冷却して精留塔に導入し、液化精留分離を行って酸素または窒素を製造する深冷ガス分離システムに関するものである。   The present invention relates to a cryogenic gas separation system in which air is compressed, purified, cooled, introduced into a rectification column, and liquefied rectification separation is performed to produce oxygen or nitrogen.

従来、空気の液化分離技術（深冷ガス分離システム）では、フィルタを通過した原料空気を圧縮機により圧縮した後、予冷器を通過させ、液化分離装置（精留塔）に供して、酸素と窒素を製造している。   Conventionally, in the air liquefaction separation technology (deep cold gas separation system), after the raw material air that has passed through the filter is compressed by a compressor, it is passed through a precooler and is supplied to a liquefaction separation device (rectification tower), where oxygen and Nitrogen is produced.

その際に、製鉄所における酸素製造プラントで用いられる深冷ガス分離システムでは、製鉄所の酸素ニーズに即して運転しているため、併産される窒素については、予冷器の冷熱源として利用する量と製鉄所内の需要を賄う量を合わせた量を超えた部分については放散され、その保有していた冷熱・除湿能は利用されていなかった。   At that time, since the cryogenic gas separation system used in the oxygen production plant at the steel works operates in accordance with the oxygen needs of the steel works, the co-produced nitrogen is used as a cold heat source for the precooler. The portion exceeding the combined amount to meet the demand in the steelworks was dissipated, and the cold heat and dehumidification capacity that was held was not used.

そこで、特許文献１に記載された技術では、圧縮機の前段において、積層式の全熱交換器を配置し、廃窒素の冷熱および除湿能により原料空気を予冷することで、圧縮機の動力を低減するようにしている。   Therefore, in the technique described in Patent Document 1, a stacked total heat exchanger is disposed in the front stage of the compressor, and the raw material air is pre-cooled by the cooling and dehumidifying ability of the waste nitrogen, so that the power of the compressor is increased. I try to reduce it.

すなわち、図３を用いて詳しく説明すると、原料空気は、フィルタ１１を通過して吸い込まれ、原料空気圧縮機（コンプレッサ）１２で約０．５ＭＰａまで昇圧された後、水洗塔１３で冷却され、分子篩吸着器（モレキュラー・シーブ吸着器、以下ＭＳ吸着器）１４で二酸化炭素と水分を除去される。そして、熱交換器１５で製品酸素および製品窒素と熱交換され、その一部は膨張タービン１６で温度を下げてから精留塔１７の低圧部１７ａに送られ、他の部分は直接精留塔１７の高圧部１７ｂに送られる。そして、精留塔低圧部１７ａの上部から製品窒素が、下部から製品酸素がそれぞれ抽出され、熱交換器１５での原料空気との熱交換を経て製鉄所へ供給される。   That is, when described in detail with reference to FIG. 3, the raw air is sucked through the filter 11, boosted to about 0.5 MPa by the raw air compressor (compressor) 12, cooled by the washing tower 13, Carbon dioxide and moisture are removed by a molecular sieve adsorber (molecular sieve adsorber, hereinafter referred to as MS adsorber) 14. Then, heat is exchanged with product oxygen and product nitrogen in the heat exchanger 15, a part of which is sent to the low pressure part 17 a of the rectification column 17 after the temperature is lowered by the expansion turbine 16, and the other part is directly in the rectification column. 17 to the high-pressure part 17b. And product nitrogen is extracted from the upper part of the rectification tower low-pressure part 17a, and product oxygen is extracted from the lower part, respectively, and is supplied to the ironworks through heat exchange with the raw material air in the heat exchanger 15.

その際に、酸素製造プラントから生産される窒素は、熱交換器１５での原料空気との熱交換後に概略１０℃程度の温度となるが、その一部は、ＭＳ吸着器１４に吸着した二酸化炭素や水分を取り外してＭＳ吸着器１４を再生する際に必要な再生用ガスや、水洗塔１３への冷却水の冷却用ガスとして用いられる。また、他の部分は、製鉄所内の需要に応じて、流量調整装置１８で流量を調整されて製鉄所内へ供給されるとともに、余った窒素（廃窒素）は放散される。   At that time, the nitrogen produced from the oxygen production plant has a temperature of about 10 ° C. after heat exchange with the raw air in the heat exchanger 15, and a part of the nitrogen dioxide adsorbed on the MS adsorber 14. It is used as a regeneration gas necessary for regenerating the MS adsorber 14 by removing carbon or moisture, or as a cooling gas for cooling water to the washing tower 13. In addition, the flow rate of the other part is adjusted by the flow rate adjusting device 18 according to the demand in the steelworks, and the remaining nitrogen (waste nitrogen) is released.

そして、特許文献１に記載の技術では、圧縮機１２の前段に積層式の全熱交換器１９を配置し、廃窒素の放散ラインから分岐をとって、廃窒素（低温乾燥窒素ガス）を積層式全熱交換器１９に導き、廃窒素の冷熱と除湿能により原料空気を予冷・除湿するようにしており、このような窒素からの低温排熱回収を行うことにより、圧縮機１２の動力の低減を図るようにしている。   In the technique described in Patent Document 1, a laminated total heat exchanger 19 is arranged in front of the compressor 12, and a waste nitrogen (low temperature dry nitrogen gas) is laminated by branching from a waste nitrogen diffusion line. The raw air is precooled and dehumidified by the cooling and dehumidifying ability of the waste nitrogen, and is led to the total heat exchanger 19, and by recovering the low-temperature exhaust heat from the nitrogen, the power of the compressor 12 can be reduced. We try to reduce it.

図４は、上記の技術で用いられる積層式全熱交換器１９を示すものである。クラフト紙等からなる波板１９ａが交互に直交して積層され、それぞれの層間にアスベスト紙等の透湿性の材料からなる隔壁１９ｂが配置されている。そして、高温高湿の原料空気と低温低湿の廃窒素が各層を交互に流れ、隔壁１９ｂを隔てて、原料空気と廃窒素の間で熱交換と湿分移動が行われる。
特開平１０−２６７５２７号公報 FIG. 4 shows a laminated total heat exchanger 19 used in the above technique. Corrugated sheets 19a made of kraft paper or the like are alternately stacked at right angles, and a partition wall 19b made of a moisture-permeable material such as asbestos paper is disposed between the layers. Then, high-temperature, high-humidity raw air and low-temperature, low-humidity waste nitrogen flow alternately in each layer, and heat exchange and moisture transfer are performed between the raw air and waste nitrogen across the partition wall 19b.
JP-A-10-267527

しかし、本発明者らが検討したところ、前記特許文献１に記載の技術では、必ずしも廃窒素からの低温排熱回収が効率良く行われているとはいえないことが分かった。   However, as a result of investigations by the present inventors, it has been found that the technique described in Patent Document 1 cannot always efficiently recover low-temperature exhaust heat from waste nitrogen.

本発明は、上記のような事情に鑑みてなされたものであり、空気を圧縮、精製、冷却して精留塔に導入し、液化精留分離を行って酸素または窒素を製造する深冷ガス分離システムにおいて、余剰の廃窒素からの低温排熱回収を効率良く行うことができ、それによって、原料空気を圧縮する圧縮機の動力を一層低減することができる深冷ガス分離システムを提供することを目的とするものである。   The present invention has been made in view of the above circumstances, and is a cryogenic gas for producing oxygen or nitrogen by compressing, purifying and cooling air, introducing it into a rectifying column, and performing liquefaction rectification separation. To provide a cryogenic gas separation system capable of efficiently recovering low-temperature exhaust heat from excess waste nitrogen in a separation system, thereby further reducing the power of a compressor for compressing raw material air. It is intended.

上記課題を解決するために、本発明は以下の特徴を有する。   In order to solve the above problems, the present invention has the following features.

［１］空気を圧縮、精製、冷却して精留塔に導入し、液化精留分離を行って酸素または窒素を製造する深冷ガス分離システムにおいて、原料空気圧縮機の入口に原料空気と精留分離で発生した低温乾燥窒素ガスとを熱交換させる回転式全熱交換器を設けたことを特徴とする深冷ガス分離システム。   [1] In a cryogenic gas separation system in which air is compressed, purified, cooled, introduced into a rectification column, and liquefied rectification separation is performed to produce oxygen or nitrogen. A cryogenic gas separation system comprising a rotary total heat exchanger for exchanging heat with low-temperature dry nitrogen gas generated by distillation separation.

［２］回転式全熱交換器の窒素ガス出口に送風機を設けたことを特徴とする前記［１］記載の深冷ガス分離システム。   [2] The cryogenic gas separation system according to [1], wherein a blower is provided at a nitrogen gas outlet of the rotary total heat exchanger.

［３］原料空気の一部が回転式全熱交換器を迂回するようにするためのバイパス回路と、該バイパス回路の起点または回路上に設けられた流量調整弁と、回転式全熱交換器を通過する原料空気の流量を測定するための原料空気流量計と、回転式全熱交換器を通過する低温乾燥窒素ガスの流量を測定するための窒素ガス流量計と、前記原料空気流量計と前記窒素ガス流量計の測定値に基づいて、回転式全熱交換器を通過する原料空気と低温乾燥窒素ガスとの流量比が所定の値になるように、前記流量調整弁の開度を制御する制御手段とを備えていることを特徴とする前記［１］または［２］に記載の深冷ガス分離システム。   [3] A bypass circuit for allowing a part of the raw material air to bypass the rotary total heat exchanger, a flow rate adjusting valve provided on the starting point of the bypass circuit or on the circuit, and the rotary total heat exchanger A raw material air flow meter for measuring the flow rate of the raw material air passing through, a nitrogen gas flow meter for measuring the flow rate of the low-temperature dry nitrogen gas passing through the rotary total heat exchanger, and the raw material air flow meter, Based on the measured value of the nitrogen gas flow meter, the opening degree of the flow rate adjusting valve is controlled so that the flow rate ratio between the raw air passing through the rotary total heat exchanger and the low temperature dry nitrogen gas becomes a predetermined value. The cryogenic gas separation system according to [1] or [2], further comprising:

本発明においては、空気を圧縮、精製、冷却して精留塔に導入し、液化精留分離を行って酸素または窒素を製造する深冷ガス分離システムにおいて、余剰の廃窒素からの低温排熱回収を効率良く行うことができ、それにより、原料空気を圧縮する圧縮機の動力を一層低減することができる。   In the present invention, in a cryogenic gas separation system in which air is compressed, purified, cooled, introduced into a rectification column, and liquefied rectification separation is performed to produce oxygen or nitrogen, low-temperature exhaust heat from excess waste nitrogen The recovery can be performed efficiently, whereby the power of the compressor that compresses the raw material air can be further reduced.

本発明の一実施形態を図面に基づいて述べる。   An embodiment of the present invention will be described with reference to the drawings.

図１は、本発明の一実施形態に係る深冷ガス分離システムの説明図である。この実施形態に係る深冷ガス分離システムは、酸素製造プラントで用いられるものであり、前述の図３に示した深冷ガス分離システムとほぼ同様の構成であるが、図３に示した深冷ガス分離システムにおける積層式全熱交換器１９に替えて、回転式全熱交換器２１を用いている点と、その回転式全熱交換器２１の廃窒素出口に送風機（混合防止用ファン）２２を設置している点が特徴である。   FIG. 1 is an explanatory diagram of a cryogenic gas separation system according to an embodiment of the present invention. The cryogenic gas separation system according to this embodiment is used in an oxygen production plant and has substantially the same configuration as the above-described cryogenic gas separation system shown in FIG. 3, but the cryogenic gas separation system shown in FIG. A rotary total heat exchanger 21 is used instead of the laminated total heat exchanger 19 in the gas separation system, and a blower (mixing prevention fan) 22 is provided at the waste nitrogen outlet of the rotary total heat exchanger 21. The feature is that it is installed.

すなわち、図１に示すように、原料空気は、フィルタ１１を通過して吸い込まれ、原料空気圧縮機（コンプレッサ）１２で約０．５ＭＰａまで昇圧された後、水洗塔１３で冷却され、分子篩吸着器（ＭＳ吸着器）１４で二酸化炭素と水分を除去される。そして、熱交換器１５で製品酸素および製品窒素と熱交換され、その一部は膨張タービン１６で温度を下げてから精留塔１７の低圧部１７ａに送られ、他の部分は直接精留塔１７の高圧部１７ｂに送られる。そして、精留塔低圧部１７ａの上部から製品窒素が、下部から製品酸素がそれぞれ抽出され、熱交換器１５での原料空気との熱交換を経て製鉄所へ供給される。   That is, as shown in FIG. 1, the raw air is sucked through the filter 11, boosted to about 0.5 MPa by the raw air compressor (compressor) 12, cooled by the washing tower 13, and adsorbed by the molecular sieve. Carbon dioxide and moisture are removed by a vessel (MS adsorber) 14. Then, heat is exchanged with product oxygen and product nitrogen in the heat exchanger 15, a part of which is sent to the low pressure part 17 a of the rectification column 17 after the temperature is lowered by the expansion turbine 16, and the other part is directly in the rectification column. 17 to the high-pressure part 17b. And product nitrogen is extracted from the upper part of the rectification tower low-pressure part 17a, and product oxygen is extracted from the lower part, respectively, and is supplied to the ironworks through heat exchange with the raw material air in the heat exchanger 15.

その際に、酸素製造プラントから生産される窒素は、熱交換器１５での原料空気との熱交換後に概略１０℃程度の温度となるが、その一部は、ＭＳ吸着器１４に吸着した二酸化炭素や水分を取り外してＭＳ吸着器１４を再生する際に必要な再生用ガスや、水洗塔１３への冷却水の冷却用ガスとして用いられる。そして、他の部分は、製鉄所内の需要に応じて、流量調整装置１８で流量を調整されて製鉄所内へ供給されるとともに、余った窒素（廃窒素）は、圧縮機１２の前段に配置された回転式全熱交換器２１に導かれて、廃窒素（低温乾燥窒素ガス）の冷熱と除湿能により原料空気の予冷・除湿を行う。なお、ここでは、深冷ガス分離システムの点検時や緊急停止時に廃窒素を放散するために、廃窒素放散用回路が設けられている。   At that time, the nitrogen produced from the oxygen production plant has a temperature of about 10 ° C. after heat exchange with the raw air in the heat exchanger 15, and a part of the nitrogen dioxide adsorbed on the MS adsorber 14. It is used as a regeneration gas necessary for regenerating the MS adsorber 14 by removing carbon or moisture, or as a cooling gas for cooling water to the washing tower 13. The other part is supplied to the steelworks after the flow rate is adjusted by the flow rate adjusting device 18 according to the demand in the steelworks, and the surplus nitrogen (waste nitrogen) is disposed in the front stage of the compressor 12. Then, the raw air is precooled and dehumidified by cooling and dehumidifying ability of waste nitrogen (low temperature dry nitrogen gas). Here, in order to dissipate waste nitrogen at the time of inspection of the cryogenic gas separation system or at an emergency stop, a circuit for disposing of waste nitrogen is provided.

図２は、この実施形態で用いる回転式全熱交換器２１を示すものである。回転式全熱交換器２１は、円板状の熱交換素子（ローター）２１ａと、ローター２１ａを回転させる駆動装置（図示せず）と、ケーシング２１ｂと、仕切り板２１ｃを備えている。ローター２１ａは、特殊セルロースを段ボール状に成形したものを所定の直径にまで螺旋状に巻き、接着したものである。また、天然やし繊維、無機質系難燃性紙等を使用したものや、アルミニューム、ステンレス鋼製の繊維または板にシリカ系の吸湿剤を塗布したものでもよい。そして、ローター２１ａはケーシング２１ｂに納められ、仕切り板２１ｃにより上部と下部に仕切られて、それぞれダクト（図示せず）に接続されている。   FIG. 2 shows a rotary total heat exchanger 21 used in this embodiment. The rotary total heat exchanger 21 includes a disk-shaped heat exchange element (rotor) 21a, a driving device (not shown) that rotates the rotor 21a, a casing 21b, and a partition plate 21c. The rotor 21a is obtained by spirally winding a special cellulose molded into a corrugated cardboard shape to a predetermined diameter. Further, natural palm fiber, inorganic flame-retardant paper or the like may be used, or aluminum or stainless steel fiber or plate coated with a silica-based moisture absorbent. The rotor 21a is housed in a casing 21b, divided into an upper part and a lower part by a partition plate 21c, and connected to ducts (not shown).

このような回転式全熱交換器２１では、まず、低温の廃窒素が通過したローター部分が廃窒素により冷却される。次に、ローター２１ａの回転により、この冷却されたローター部分を高温の原料空気が通過し、原料空気と当該ローター部分との間での熱交換により原料空気の温度は低下し、当該ローター部分の温度は上昇する。温度の上昇した当該ローター部分は回転して再び廃窒素が通過し、廃窒素により冷却される。このようにして、ローター２１ａの回転によって高温の原料空気から低温の廃窒素へ熱が移動し、原料空気が冷却される。同様にして、高湿の原料空気から低湿の廃窒素（絶対湿度０ｍｍｇ）へ湿分が移動し、原料空気が除湿される。   In such a rotary total heat exchanger 21, first, the rotor portion through which the low temperature waste nitrogen has passed is cooled by the waste nitrogen. Next, due to the rotation of the rotor 21a, the high-temperature raw material air passes through the cooled rotor portion, and the temperature of the raw material air decreases due to the heat exchange between the raw material air and the rotor portion. The temperature rises. The rotor portion where the temperature has risen rotates and waste nitrogen passes again, and is cooled by the waste nitrogen. In this manner, heat is transferred from the high temperature raw material air to the low temperature waste nitrogen by the rotation of the rotor 21a, and the raw material air is cooled. Similarly, moisture moves from high-humidity raw air to low-humidity waste nitrogen (absolute humidity 0 mmg), and the raw air is dehumidified.

このようにして、回転式全熱交換器２１では、原料空気と廃窒素との全熱交換がローター２１ａを介して連続的に行われ、特に、湿分の移動は、前述の積層式全熱交換器１９のような隔壁１９ｂを透過する必要が無いため高効率である。また、廃窒素と原料空気が交互に逆方向に通過するため、隔壁１９ｂの目詰まり防止等のメンテナンスも不要である。   Thus, in the rotary total heat exchanger 21, the total heat exchange between the raw air and the waste nitrogen is continuously performed via the rotor 21a. In particular, the movement of moisture is performed by the above-described stacked total heat. Since it is not necessary to permeate the partition wall 19b like the exchanger 19, it is highly efficient. Further, since waste nitrogen and raw material air alternately pass in the opposite direction, maintenance such as prevention of clogging of the partition walls 19b is unnecessary.

なお、回転式全熱交換器２１では、ローター２１ａの回転により若干量の排窒素が原料空気側へ移動することが見込まれるが、廃窒素が原料空気側へ混入すると酸素製造プラント全体の酸素生産量が低下するため、回転式全熱交換器２１の廃窒素出口に設置した混合防止用ファン２２によって廃窒素側の静圧を原料空気側の静圧より低くすることで、リーク方向を空気側から廃窒素側とし、廃窒素の原料空気側への混入を防止するようにしている。   In the rotary total heat exchanger 21, it is expected that a small amount of exhaust nitrogen moves to the raw material air side due to the rotation of the rotor 21 a, but if waste nitrogen enters the raw material air side, oxygen production of the entire oxygen production plant Since the amount decreases, the static pressure on the waste nitrogen side is made lower than the static pressure on the raw material air side by the mixing prevention fan 22 installed at the waste nitrogen outlet of the rotary total heat exchanger 21, so that the leakage direction is set to the air side. In order to prevent the waste nitrogen from entering the raw material air side.

ここで、通常、回転式全熱交換器２１に供給できる廃窒素の量は、製鉄所内の需要量の変動に伴って変動する。一方、回転式全熱交換器２１の全熱交換効率は、通過する原料空気と廃窒素の流量比（原料空気流量／廃窒素流量）によって変化する。そこで、この実施形態においては、廃窒素の供給量の変動に応じて、回転式全熱交換器２１を通過させる原料空気の量を調整することによって、回転式全熱交換器２１における原料空気と廃窒素の流量比を適切な値に保つことで、良好な全熱交換効率が得られるようにし、廃窒素からの低温排熱を可及的に回収できるようにしている。   Here, usually, the amount of waste nitrogen that can be supplied to the rotary total heat exchanger 21 varies as the demand in the steel works varies. On the other hand, the total heat exchange efficiency of the rotary total heat exchanger 21 varies depending on the flow rate ratio of the raw material air and waste nitrogen that passes therethrough (raw material air flow rate / waste nitrogen flow rate). Therefore, in this embodiment, by adjusting the amount of raw material air that passes through the rotary total heat exchanger 21 according to the fluctuation of the supply amount of waste nitrogen, the raw material air in the rotary total heat exchanger 21 and By maintaining the flow rate ratio of waste nitrogen at an appropriate value, good total heat exchange efficiency can be obtained, and low-temperature exhaust heat from waste nitrogen can be recovered as much as possible.

すなわち、この実施形態においては、図１に示すように、原料空気の一部が回転式全熱交換器２１を迂回するようにするためのバイパス回路と、そのバイパス回路上に設けられた流量調整弁（二方弁）３１と、回転式全熱交換器２１を通過する原料空気の流量を測定するために回転式全熱交換器２１の原料空気出口に設けられた原料空気流量計３２と、回転式全熱交換器２１を通過する廃窒素の流量を測定するために回転式全熱交換器２１の廃窒素入口に設けられた廃窒素流量計３３と、流量調整弁３１の開度を制御する制御装置（図示せず）とを備えている。そして、制御装置は、原料空気流量計３２と廃窒素流量計３３の測定値に基づいて、回転式全熱交換器２１を通過する原料空気と廃窒素の流量比が、予め実験的に求めておいた良好な全熱交換効率が得られる適切な流量比となるように、流量調整弁３１の開度を制御する。   That is, in this embodiment, as shown in FIG. 1, a bypass circuit for allowing a part of the raw air to bypass the rotary total heat exchanger 21, and a flow rate adjustment provided on the bypass circuit A valve (two-way valve) 31, a raw material air flow meter 32 provided at the raw air outlet of the rotary total heat exchanger 21 to measure the flow rate of the raw air passing through the rotary total heat exchanger 21, In order to measure the flow rate of waste nitrogen passing through the rotary total heat exchanger 21, the opening degree of the waste nitrogen flow meter 33 provided at the waste nitrogen inlet of the rotary total heat exchanger 21 and the flow rate adjustment valve 31 is controlled. And a control device (not shown). Then, based on the measured values of the raw material air flow meter 32 and the waste nitrogen flow meter 33, the control device experimentally obtains in advance a flow rate ratio between the raw air passing through the rotary total heat exchanger 21 and the waste nitrogen. The opening degree of the flow rate adjusting valve 31 is controlled so as to obtain an appropriate flow rate ratio at which good total heat exchange efficiency is obtained.

なお、ここでは、バイパス回路上に流量調整弁（二方弁）３１を設けているが、バイパス回路の起点に流量調整弁（三方弁）を設けるようにしてもよい。また、原料空気流量計３２を回転式全熱交換器２１の原料空気入口に設けるようにしてもよいし、廃窒素流量計３３を回転式全熱交換器２１の廃窒素出口に設けるようにしてもよい。   Here, the flow rate adjustment valve (two-way valve) 31 is provided on the bypass circuit, but a flow rate adjustment valve (three-way valve) may be provided at the starting point of the bypass circuit. Further, the raw material air flow meter 32 may be provided at the raw material air inlet of the rotary total heat exchanger 21, or the waste nitrogen flow meter 33 may be provided at the waste nitrogen outlet of the rotary total heat exchanger 21. Also good.

上記のようにして、この実施形態に係る深冷ガス分離システムにおいては、全熱交換効率の優れた回転式全熱交換器２１を用いて原料空気と廃窒素の全熱交換を行うようにしているので、廃窒素からの低温排熱回収を効率良く行うことができる。また、廃窒素出口に送風機２２を設けたことにより、廃窒素の原料空気側への混入を防止できる。さらに、回転式全熱交換器２１における原料空気と廃窒素の流量比を適切な値となるように、回転式全熱交換器２１を通過させる原料空気の量を調整しているので、より良好な全熱交換効率が得られる。その結果、原料空気圧縮機１２の動力を大幅に低減することができる。   As described above, in the cryogenic gas separation system according to this embodiment, total heat exchange between the raw air and waste nitrogen is performed using the rotary total heat exchanger 21 having excellent total heat exchange efficiency. Therefore, low-temperature exhaust heat recovery from waste nitrogen can be performed efficiently. Moreover, by providing the blower 22 at the waste nitrogen outlet, it is possible to prevent waste nitrogen from being mixed into the raw material air side. Furthermore, since the amount of the raw material air that passes through the rotary total heat exchanger 21 is adjusted so that the flow rate ratio between the raw air and the waste nitrogen in the rotary total heat exchanger 21 becomes an appropriate value, it is better. High total heat exchange efficiency. As a result, the power of the raw material air compressor 12 can be significantly reduced.

例えば、この実施形態に係る深冷ガス分離システムにおいては、廃窒素流量５００００Ｎｍ３／ｈ程度の場合、１２℃の廃窒素により原料空気を予冷・除湿することで、廃窒素による原料空気の予冷・除湿を行わない場合に対する圧縮機動力の低減割合を、図３に示した従来の深冷ガス分離システムに比べて、約３０％向上させることができる。 For example, in the cryogenic gas separation system according to this embodiment, when the waste nitrogen flow rate is about 50,000 Nm 3 / h, the raw air is precooled and dehumidified with waste nitrogen at 12 ° C. Compared with the conventional cryogenic gas separation system shown in FIG. 3, the reduction rate of the compressor power with respect to the case where dehumidification is not performed can be improved by about 30%.

本発明の一実施形態の説明図である。It is explanatory drawing of one Embodiment of this invention. 本発明の一実施形態において用いる回転式全熱交換器の説明図である。It is explanatory drawing of the rotary total heat exchanger used in one Embodiment of this invention. 従来技術の説明図である。It is explanatory drawing of a prior art. 従来技術において用いられる積層式全熱交換器の説明図である。It is explanatory drawing of the laminated | stacked total heat exchanger used in a prior art.

符号の説明Explanation of symbols

１１ フィルタ
１２ 原料空気圧縮機
１３ 水洗塔
１４ 分子篩吸着器（ＭＳ吸着器）
１５ 熱交換器
１６ 膨張タービン
１７ 精留塔
１７ａ 精留塔の低圧部
１７ｂ 精留塔の高圧部
１８ 流量調整装置
１９ 積層式全熱交換器
１９ａ 波板
１９ｂ 隔壁
２１ 回転式全熱交換器
２１ａ ローター
２１ｃ ケーシング
２１ｂ 仕切り板
２２ 送風機（混合防止ファン）
３１ 流量調整弁
３２ 原料空気流量計
３３ 廃窒素流量計 11 Filter 12 Raw material air compressor 13 Flushing tower 14 Molecular sieve adsorber (MS adsorber)
DESCRIPTION OF SYMBOLS 15 Heat exchanger 16 Expansion turbine 17 Rectification tower 17a Low pressure part of a rectification tower 17b High pressure part of a rectification tower 18 Flow control device 19 Laminated total heat exchanger 19a Corrugated plate 19b Bulkhead 21 Rotary total heat exchanger 21a Rotor 21c Casing 21b Partition plate 22 Blower (mixing prevention fan)
31 Flow control valve 32 Raw material air flow meter 33 Waste nitrogen flow meter

Claims (3)

空気を圧縮、精製、冷却して精留塔に導入し、液化精留分離を行って酸素または窒素を製造する深冷ガス分離システムにおいて、原料空気圧縮機の入口に原料空気と精留分離で発生した低温乾燥窒素ガスとを熱交換させる回転式全熱交換器を設けたことを特徴とする深冷ガス分離システム。   In a cryogenic gas separation system that compresses, purifies and cools air, introduces it into the rectification column, and produces oxygen or nitrogen by performing liquefied rectification separation, the raw air and rectification separation at the inlet of the raw material air compressor A cryogenic gas separation system comprising a rotary total heat exchanger for exchanging heat with generated low-temperature dry nitrogen gas. 回転式全熱交換器の窒素ガス出口に送風機を設けたことを特徴とする請求項１記載の深冷ガス分離システム。   The cryogenic gas separation system according to claim 1, wherein a blower is provided at a nitrogen gas outlet of the rotary total heat exchanger. 原料空気の一部が回転式全熱交換器を迂回するようにするためのバイパス回路と、該バイパス回路の起点または回路上に設けられた流量調整弁と、回転式全熱交換器を通過する原料空気の流量を測定するための原料空気流量計と、回転式全熱交換器を通過する低温乾燥窒素ガスの流量を測定するための窒素ガス流量計と、前記原料空気流量計と前記窒素ガス流量計の測定値に基づいて、回転式全熱交換器を通過する原料空気と低温乾燥窒素ガスとの流量比が所定の値になるように、前記流量調整弁の開度を制御する制御手段とを備えていることを特徴とする請求項１または２に記載の深冷ガス分離システム。   A bypass circuit for allowing a part of the raw air to bypass the rotary total heat exchanger, a flow regulating valve provided on the bypass circuit or on the circuit, and the rotary total heat exchanger. A raw material air flow meter for measuring the flow rate of raw material air, a nitrogen gas flow meter for measuring the flow rate of low-temperature dry nitrogen gas passing through the rotary total heat exchanger, the raw material air flow meter and the nitrogen gas Control means for controlling the opening degree of the flow rate adjusting valve so that the flow rate ratio of the raw material air passing through the rotary total heat exchanger and the low-temperature dry nitrogen gas becomes a predetermined value based on the measured value of the flow meter The cryogenic gas separation system according to claim 1 or 2, characterized by comprising:
JP2006081849A 2006-03-24 2006-03-24 Cryogenic gas separation system Pending JP2007255802A (en)

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Publication number Priority date Publication date Assignee Title
CN103123203A (en) * 2013-02-22 2013-05-29 河南开元空分集团有限公司 Method of preparing pure nitrogen by using exhaust gas with nitrogen to carry out once-more cryogenic distillation
CN103123203B (en) * 2013-02-22 2015-03-04 河南开元空分集团有限公司 Method of preparing pure nitrogen by using exhaust gas with nitrogen to carry out once-more cryogenic distillation

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