JP2000018813A - Method and device for producing nitrogen - Google Patents
Method and device for producing nitrogenInfo
- Publication number
- JP2000018813A JP2000018813A JP10175985A JP17598598A JP2000018813A JP 2000018813 A JP2000018813 A JP 2000018813A JP 10175985 A JP10175985 A JP 10175985A JP 17598598 A JP17598598 A JP 17598598A JP 2000018813 A JP2000018813 A JP 2000018813A
- Authority
- JP
- Japan
- Prior art keywords
- nitrogen
- enriched
- distillation column
- oxygen
- gas
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 title claims abstract description 218
- 229910052757 nitrogen Inorganic materials 0.000 title claims abstract description 88
- 238000000034 method Methods 0.000 title claims abstract description 20
- 239000001301 oxygen Substances 0.000 claims abstract description 102
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 102
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 101
- 239000007789 gas Substances 0.000 claims abstract description 86
- 239000007788 liquid Substances 0.000 claims abstract description 51
- 229910001873 dinitrogen Inorganic materials 0.000 claims abstract description 42
- 230000008016 vaporization Effects 0.000 claims abstract description 15
- 238000010992 reflux Methods 0.000 claims abstract description 14
- 238000011084 recovery Methods 0.000 claims abstract description 12
- 238000009834 vaporization Methods 0.000 claims abstract description 10
- 230000001174 ascending effect Effects 0.000 claims abstract description 6
- 238000004821 distillation Methods 0.000 claims description 120
- 238000004519 manufacturing process Methods 0.000 claims description 36
- 239000002994 raw material Substances 0.000 claims description 24
- 238000005292 vacuum distillation Methods 0.000 claims description 11
- 238000001816 cooling Methods 0.000 claims description 9
- 230000006837 decompression Effects 0.000 claims description 4
- 239000000463 material Substances 0.000 abstract 1
- 239000012530 fluid Substances 0.000 description 14
- 230000000630 rising effect Effects 0.000 description 8
- 230000007423 decrease Effects 0.000 description 5
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 4
- 230000006835 compression Effects 0.000 description 4
- 238000007906 compression Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 238000007654 immersion Methods 0.000 description 4
- 239000002912 waste gas Substances 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 229910002092 carbon dioxide Inorganic materials 0.000 description 2
- 239000001569 carbon dioxide Substances 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 230000008929 regeneration Effects 0.000 description 2
- 238000011069 regeneration method Methods 0.000 description 2
- 239000002808 molecular sieve Substances 0.000 description 1
- 150000002926 oxygen Chemical class 0.000 description 1
- 238000012856 packing Methods 0.000 description 1
- 238000005057 refrigeration Methods 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- 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
- F25J3/0443—A main column system not otherwise provided, e.g. a modified double column flowsheet
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
- F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
- F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
- F25J3/04006—Providing pressurised feed air or process streams within or from the air fractionation unit
- F25J3/04048—Providing pressurised feed air or process streams within or from the air fractionation unit by compression of cold gaseous streams, e.g. intermediate or oxygen enriched (waste) streams
- F25J3/0406—Providing pressurised feed air or process streams within or from the air fractionation unit by compression of cold gaseous streams, e.g. intermediate or oxygen enriched (waste) streams of nitrogen
-
- 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
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
- F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
- F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
- F25J3/04248—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion
- F25J3/04375—Details relating to the work expansion, e.g. process parameter etc.
- F25J3/04393—Details relating to the work expansion, e.g. process parameter etc. using multiple or multistage gas work expansion
-
- 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
- F25J2240/00—Processes or apparatus involving steps for expanding of process streams
- F25J2240/02—Expansion of a process fluid in a work-extracting turbine (i.e. isentropic expansion), e.g. of the feed stream
- F25J2240/04—Multiple expansion turbines in parallel
-
- 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
-
- 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
- F25J2250/00—Details related to the use of reboiler-condensers
- F25J2250/02—Bath type boiler-condenser using thermo-siphon effect, e.g. with natural or forced circulation or pool boiling, i.e. core-in-kettle heat exchanger
-
- 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
- F25J2250/00—Details related to the use of reboiler-condensers
- F25J2250/20—Boiler-condenser with multiple exchanger cores in parallel or with multiple re-boiling or condensing streams
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Mechanical Engineering (AREA)
- Thermal Sciences (AREA)
- General Engineering & Computer Science (AREA)
- Separation By Low-Temperature Treatments (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、窒素製造方法及び
装置に関し、詳しくは、圧縮，精製，冷却した原料空気
を主蒸留塔に導入して低温蒸留することにより窒素ガス
を分離し、製品として採取する窒素製造方法及び装置に
関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for producing nitrogen. More specifically, the present invention relates to a method for separating nitrogen gas by introducing compressed, purified and cooled raw material air into a main distillation column and performing low-temperature distillation on the air. The present invention relates to a method and apparatus for producing nitrogen.
【０００２】[0002]
【従来の技術及び発明が解決しようとする課題】原料空
気を低温蒸留して窒素ガスを採取する窒素製造装置にお
いて、設備の増加を抑えながら、窒素の製造原単位を低
減することは、重要な技術的課題であり、従来から様々
な方式が提案されている。この技術的課題を解決するた
めの一つのプロセスとして、特開平３−１３７４８４公
報に記載された窒素製造プロセスが知られている。図２
は、該公報に記載された窒素製造プロセスの系統図を示
すものである。以下、図２を参照しながら、前記プロセ
スにより窒素を製造する手順を説明する。2. Description of the Related Art In a nitrogen production apparatus for extracting nitrogen gas by low-temperature distillation of raw material air, it is important to reduce the unit production of nitrogen while suppressing an increase in equipment. This is a technical problem, and various methods have been conventionally proposed. As one process for solving this technical problem, a nitrogen production process described in Japanese Patent Application Laid-Open No. 3-137484 is known. FIG.
1 shows a system diagram of the nitrogen production process described in the publication. Hereinafter, the procedure for producing nitrogen by the above process will be described with reference to FIG.
【０００３】経路１１から導入された原料空気は、原料
空気圧縮機１で１０ｋｇ／ｃｍ２ａｂｓ．程度に圧縮さ
れた後、アフタークーラー１ａで冷却される。この原料
空気は、モレキュラシーブ等を充填した前処理設備２に
導入され、二酸化炭素，水分等の不純物が吸着・除去さ
れて精製される。精製後の原料空気は、経路１２を通
り、主熱交換器３で、後述する製品窒素ガス及び酸素富
化空気と熱交換し、露点温度付近まで冷却された後、経
路１３を通って蒸留塔４の下部に導入される。[0003] The raw material air introduced from the passage 11 is supplied to the raw material air compressor 1 at 10 kg / cm 2 abs. After being compressed to the extent, it is cooled by the aftercooler 1a. This raw material air is introduced into a pretreatment facility 2 filled with molecular sieves and the like, and is purified by absorbing and removing impurities such as carbon dioxide and moisture. The purified raw material air passes through the path 12 and exchanges heat with the product nitrogen gas and oxygen-enriched air described later in the main heat exchanger 3 and is cooled to a temperature near the dew point. 4 is introduced at the bottom.
【０００４】蒸留塔４では、塔内を上昇するガスと頂部
のリボイラー／コンデンサー５で凝縮・液化されて塔内
を下降する液との気液接触により低温蒸留が行われ、頂
部から窒素ガスが、底部から酸素富化液化空気がそれぞ
れ抜き出される。[0004] In the distillation column 4, low-temperature distillation is performed by gas-liquid contact between a gas rising in the column and a liquid condensed and liquefied in the top reboiler / condenser 5 and descending in the column, and nitrogen gas is discharged from the top. , Oxygen-enriched liquefied air is withdrawn from the bottom.
【０００５】塔頂部から経路１４に抜き出された窒素ガ
スの一部は、経路１６，過冷器６、経路１７，主熱交換
器３を通って昇温され、経路１８から製品窒素ガスＧＮ
として回収される。残りの窒素ガスは、リボイラー／コ
ンデンサー５で凝縮液化されて経路１５を通り、還流液
として蒸留塔４に戻される。A part of the nitrogen gas extracted from the top of the tower to the passage 14 is heated through the passage 16, the subcooler 6, the passage 17, and the main heat exchanger 3, and the product nitrogen gas GN is passed through the passage 18.
Will be collected as The remaining nitrogen gas is condensed and liquefied by the reboiler / condenser 5, passes through the path 15, and is returned to the distillation column 4 as a reflux liquid.
【０００６】また、蒸留塔４の底部から経路１９に抜き
出された酸素富化液化空気は、過冷器６で冷却された
後、経路２０を通って減圧弁２０ａで減圧された後、経
路２１を通ってリボイラー／コンデンサー５に導入さ
れ、前記窒素ガスとの熱交換により気化されて酸素富化
空気となる。このときの気化圧力は、リボイラー／コン
デンサー５における窒素ガスとの温度差が適当となるよ
うに前記減圧弁２０ａで調節される。リボイラー／コン
デンサー５において生成した酸素富化空気は、経路２２
を通り、過冷器６で昇温された後、経路２３を通って２
つに分岐される。一方の経路２４に分岐した酸素富化空
気は、主熱交換器３で昇温された後、経路２５を通って
膨張タービン８に導入され、膨張して寒冷を発生し、経
路２６を通って主熱交換器３で寒冷が回収され、常温と
なって経路２７から廃ガスＷＧとして抜き出される。こ
の廃ガスの少なくとも一部は、経路２８を通って前処理
設備２の再生ガスとして使用される。[0006] The oxygen-enriched liquefied air extracted from the bottom of the distillation column 4 to the path 19 is cooled by the subcooler 6, passes through the path 20, is depressurized by the pressure reducing valve 20a, and then passes through the path. The gas is introduced into the reboiler / condenser 5 through 21 and is vaporized by heat exchange with the nitrogen gas to become oxygen-enriched air. The vaporization pressure at this time is adjusted by the pressure reducing valve 20a so that the temperature difference from the nitrogen gas in the reboiler / condenser 5 becomes appropriate. The oxygen-enriched air produced in reboiler / condenser 5
Through the subcooler 6 and then through the path 23 to 2
Branches into two. The oxygen-enriched air branched to one path 24 is heated in the main heat exchanger 3, then introduced into the expansion turbine 8 through the path 25, expanded to generate cold, and passed through the path 26. The cold is recovered in the main heat exchanger 3, reaches room temperature, and is extracted from the path 27 as waste gas WG. At least a part of the waste gas is used as a regeneration gas of the pretreatment facility 2 through the path 28.
【０００７】前記経路２３から経路２９に分岐した酸素
富化空気は、低温圧縮機９で圧縮され、経路３０を通
り、主熱交換器３で冷却された後、経路３１を通って蒸
留塔４の下部に塔内の上昇ガスとして循環導入される。The oxygen-enriched air branched from the path 23 to the path 29 is compressed by the low-temperature compressor 9, passes through the path 30, is cooled by the main heat exchanger 3, passes through the path 31, and then passes through the path 31. Is circulated into the lower part of the tower as rising gas.
【０００８】このように、酸素富化空気の一部を膨張タ
ービン８の動力の一部によって圧縮し、蒸留塔４に循環
導入することにより、窒素の回収率を向上させるように
している。また、膨張タービン８の動力の一部を動力回
収装置１０によって回収し、これをコールドボックス外
に放出することによって寒冷を発生させている。As described above, a part of the oxygen-enriched air is compressed by a part of the power of the expansion turbine 8 and circulated into the distillation column 4 to improve the nitrogen recovery rate. Further, part of the power of the expansion turbine 8 is recovered by the power recovery device 10 and is discharged outside the cold box to generate cold.
【０００９】このようなプロセスによれば、蒸留塔４の
塔底から抜き出した酸素富化液化空気を気化させ、酸素
富化空気として再び蒸留塔４の下部に循環導入させてい
るため、この流体の酸素濃度は、原料空気中の酸素濃度
よりも高くなっている。このような酸素富化液化空気を
コンデンサー・リボイラー５で窒素ガスとの熱交換によ
り気化させるためには、前述のように、温度差が適当に
なるような圧力まで減圧弁２０ａで減圧させなければな
らない。この気化圧力は、液中の酸素濃度に関係し、酸
素濃度が高くなるのに伴って低い圧力となる。したがっ
て、低温圧縮機９の吸入圧力が低下するので、酸素富化
空気の循環量の減少につながり、窒素の製造原単位の低
減効果を十分に達成しているとはいえない。According to such a process, the oxygen-enriched liquefied air extracted from the bottom of the distillation column 4 is vaporized and circulated again as oxygen-enriched air to the lower portion of the distillation column 4. Is higher than the oxygen concentration in the raw material air. In order to vaporize such oxygen-enriched liquefied air by heat exchange with nitrogen gas in the condenser / reboiler 5, as described above, the pressure must be reduced by the pressure reducing valve 20a to a pressure at which the temperature difference becomes appropriate. No. This vaporization pressure is related to the oxygen concentration in the liquid, and becomes lower as the oxygen concentration increases. Therefore, the suction pressure of the low-temperature compressor 9 decreases, which leads to a decrease in the amount of circulating oxygen-enriched air, and it cannot be said that the effect of reducing the unit production of nitrogen is sufficiently achieved.
【００１０】また、窒素回収率を向上させて原単位を改
善する他の方法として、米国特許第４８４８９９６号明
細書に記載されている方法が知られている。この方法で
は、主蒸留塔の塔底から抜き出した酸素富化液化空気を
補助蒸留塔の頂部に導入している。この補助蒸留塔の底
部は、主蒸留塔の頂部とコンデンサー・リボイラーによ
って熱的にリンクしており、主蒸留塔の頂部窒素ガスと
補助蒸留塔底部の酸素富化液とが熱交換する。これによ
り、窒素ガスは凝縮し、還流として主蒸留塔に供給され
るとともに、酸素富化液は気化し、補助蒸留塔内を上昇
して蒸留される。補助蒸留塔の頂部からは、大気圧より
高い圧力の空気成分に近いガスが抜き出され、寒冷を回
収した後、循環ガスとして原料空気圧縮機の中間段に導
入され、外部から導入された原料空気と共に圧縮され、
再び主蒸留塔に循環導入される。As another method for improving the basic unit by improving the nitrogen recovery rate, a method described in US Pat. No. 4,848,996 is known. In this method, oxygen-enriched liquefied air extracted from the bottom of the main distillation column is introduced into the top of the auxiliary distillation column. The bottom of the auxiliary distillation column is thermally linked to the top of the main distillation column by a condenser reboiler, and heat exchange occurs between nitrogen gas at the top of the main distillation column and the oxygen-enriched liquid at the bottom of the auxiliary distillation column. Thereby, the nitrogen gas is condensed and supplied as reflux to the main distillation column, and the oxygen-enriched liquid is vaporized and ascends in the auxiliary distillation column to be distilled. From the top of the auxiliary distillation column, a gas close to the air component with a pressure higher than atmospheric pressure is extracted, and after recovering the cold, it is introduced into the intermediate stage of the raw material air compressor as circulating gas, and the raw material introduced from the outside Compressed with air,
It is circulated again into the main distillation column.
【００１１】このように、大気圧よりも圧力が高く、空
気に近い成分のガスを原料の一部とし、再圧縮して循環
させることにより、空気分離に必要な原料空気の全てを
大気圧から圧縮する場合と比較し、窒素の製造原単位を
低減させるようにしている。しかし、主蒸留塔の底部か
ら抜き出された酸素富化液化空気は、補助蒸留塔の底部
のコンデンサー・リボイラーにおいて、より酸素濃度の
高い酸素富化液と窒素ガスとの温度差が適当になるよう
に減圧されて導入されるため、補助蒸留塔の頂部から抜
き出す循環ガスの圧力も低くなり、原料空気圧縮機に循
環させるガスの圧力が低下してしまうとともに、補助蒸
留塔から抜き出した循環ガスを常温まで加熱した後に原
料空気圧縮機に導入するため、熱交換器や配管による圧
力損失が大きくなり、その分循環量が減少するから、窒
素の製造原単位の低減効果は十分とはいえない。As described above, by making a gas having a pressure higher than the atmospheric pressure and a component close to the air as a part of the raw material, recompressing and circulating the raw material, all of the raw material air required for air separation is removed from the atmospheric pressure. Compared to the case of compression, the production unit of nitrogen is reduced. However, the oxygen-enriched liquefied air extracted from the bottom of the main distillation column has a suitable temperature difference between the oxygen-enriched liquid with higher oxygen concentration and nitrogen gas in the condenser reboiler at the bottom of the auxiliary distillation column. As a result, the pressure of the circulating gas extracted from the top of the auxiliary distillation column also decreases, and the pressure of the gas circulated to the raw material air compressor decreases. Is introduced into the raw material air compressor after it has been heated to room temperature, the pressure loss due to the heat exchanger and piping increases, and the amount of circulation decreases accordingly, so the effect of reducing the unit production of nitrogen cannot be said to be sufficient. .
【００１２】そこで本発明は、従来よりもプロセス全体
の動力の増加を極力抑え、設備を極力追加しない条件に
おいて、窒素回収率を向上させて窒素の製造原単位を低
減できる窒素製造方法及び装置を提供することを目的と
している。Accordingly, the present invention provides a nitrogen production method and apparatus capable of improving the nitrogen recovery rate and reducing the nitrogen production unit under the condition that the increase in the power of the whole process is suppressed as much as possible and the equipment is not added as much as possible. It is intended to provide.
【００１３】[0013]
【課題を解決するための手段】上記目的を達成するた
め、本発明の窒素製造方法は、圧縮，精製，冷却した原
料空気を主蒸留塔に導入して低温蒸留し、酸素富化液化
空気と窒素ガスとに分離して分離した窒素ガスを製品と
して採取する窒素製造方法において、前記酸素富化液化
空気の一部を減圧後に前記窒素ガスと熱交換させて気化
し、補助蒸留塔に導入するとともに、前記酸素富化液化
空気の残部を減圧して前記補助蒸留塔に導入し、該補助
蒸留塔での蒸留により酸素富化液と窒素富化ガスとに分
離し、前記酸素富化液を減圧後に前記窒素ガスと熱交換
させて気化することにより酸素富化ガスを生成し、生成
した酸素富化ガスを膨張させるとともに、前記窒素富化
ガスを圧縮して前記主蒸留塔に循環導入することを特徴
としている。In order to achieve the above object, a method for producing nitrogen according to the present invention comprises introducing a compressed, purified, and cooled raw material air into a main distillation column to perform low-temperature distillation to obtain oxygen-enriched liquefied air. In the method for producing nitrogen, in which nitrogen gas separated and separated as nitrogen gas is collected as a product, a part of the oxygen-enriched liquefied air is vaporized by heat exchange with the nitrogen gas after decompression and introduced into an auxiliary distillation column. At the same time, the remaining portion of the oxygen-enriched liquefied air is decompressed and introduced into the auxiliary distillation column, and is separated into an oxygen-enriched solution and a nitrogen-enriched gas by distillation in the auxiliary distillation column. Oxygen-enriched gas is generated by heat exchange with the nitrogen gas and vaporized after decompression, and the generated oxygen-enriched gas is expanded, and the nitrogen-enriched gas is compressed and circulated and introduced into the main distillation column. It is characterized by:
【００１４】さらに、本発明の窒素製造方法は、前記圧
縮した窒素富化ガスを、前記主蒸留塔に導入する原料空
気の導入位置より少なくとも１理論段上から主蒸留塔に
導入すること、あるいは、該窒素富化ガスを、前記主蒸
留塔に導入する前の原料空気に混合することを特徴とし
ている。また、窒素富化ガスを圧縮する前の温度が、蒸
留温度レベルから常温までの範囲であること、前記主蒸
留塔から導出して減圧する前の酸素富化液化空気を、前
記窒素ガス及び前記窒素富化ガス及び前記酸素富化ガス
のいずれか少なくとも一つで冷却することを特徴として
いる。Further, in the method for producing nitrogen according to the present invention, the compressed nitrogen-enriched gas is introduced into the main distillation column from at least one theoretical stage above a position where the feed air introduced into the main distillation column is introduced, or The method is characterized in that the nitrogen-enriched gas is mixed with the raw material air before being introduced into the main distillation column. Further, the temperature before compressing the nitrogen-enriched gas is in the range from the distillation temperature level to room temperature, and the oxygen-enriched liquefied air before being decompressed by being derived from the main distillation column is subjected to the nitrogen gas and the It is characterized by cooling with at least one of a nitrogen-enriched gas and the oxygen-enriched gas.
【００１５】本発明の窒素製造装置は、原料空気を圧
縮，精製、冷却して低温蒸留することにより窒素を採取
する窒素製造装置において、圧縮，精製した原料空気を
低温蒸留で得られた低温戻りガスとの熱交換により冷却
する主熱交換器と、冷却した原料空気を低温蒸留して窒
素ガスと酸素富化液化空気とに分離する主蒸留塔と、前
記主蒸留塔で得られた酸素富化液化空気の一部を減圧・
気化した後に上昇ガスとして導入するとともに、前記主
蒸留塔で得られた酸素富化液化空気の残部を還流液とし
て導入し、低温蒸留して酸素富化液と窒素富化ガスとに
分離する補助蒸留塔と、前記窒素ガスと前記酸素富化液
化空気及び前記酸素富化液とを熱交換させ、窒素ガスを
液化して前記主蒸留塔の還流液を生成するとともに、酸
素富化液化空気及び酸素富化液を気化するコンデンサー
・リボイラーと、該コンデンサー・リボイラーで酸素富
化液を気化して生成した酸素富化ガスを膨張させて寒冷
を発生する寒冷タービン及び動力を発生する駆動タービ
ンと、前記窒素富化ガスを圧縮する循環圧縮機とを備え
たことを特徴としている。The nitrogen production apparatus according to the present invention is a nitrogen production apparatus for compressing, purifying, cooling, and cryogenically distilling raw air to collect nitrogen, wherein the compressed and purified raw air is cooled to a low temperature by cryogenic distillation. A main heat exchanger for cooling by heat exchange with gas, a main distillation column for low-temperature distillation of the cooled raw material air to separate it into nitrogen gas and oxygen-enriched liquefied air, and an oxygen-rich gas obtained in the main distillation column. Decompress part of the liquefied air
After being introduced as a rising gas after vaporization, the remainder of the oxygen-enriched liquefied air obtained in the main distillation column is introduced as a reflux liquid, which is subjected to low-temperature distillation to separate it into an oxygen-enriched liquid and a nitrogen-enriched gas. Distillation tower, heat exchange between the nitrogen gas and the oxygen-enriched liquefied air and the oxygen-enriched liquid, liquefying the nitrogen gas to produce the reflux liquid of the main distillation column, oxygen-enriched liquefied air and A condenser reboiler for vaporizing the oxygen-enriched liquid, a cold turbine for generating cold by expanding the oxygen-enriched gas generated by vaporizing the oxygen-enriched liquid with the condenser reboiler, and a drive turbine for generating power, A circulating compressor for compressing the nitrogen-enriched gas.
【００１６】さらに、本発明の窒素製造装置は、前記主
蒸留塔及び前記補助蒸留塔の少なくとも一つが充填式蒸
留塔であること、前記コンデンサー・リボイラーが、ド
ライタイプであること、前記コンデンサー・リボイラー
が、前記酸素富化液化空気を気化させるものと、前記酸
素富化液を気化させるものとに分割して別々に構成され
ていることを特徴としている。また、前記循環圧縮機が
低温仕様のものであり、前記寒冷タービン又は駆動ター
ビンと同軸上に連結して構成されていることを特徴とし
ている。Further, in the nitrogen production apparatus of the present invention, it is preferable that at least one of the main distillation column and the auxiliary distillation column is a packed distillation column, the condenser reboiler is a dry type, However, it is characterized in that the oxygen-enriched liquefied air is vaporized and the oxygen-enriched liquid is vaporized separately. Further, the circulating compressor is of a low temperature specification, and is configured so as to be coaxially connected to the cold turbine or the drive turbine.
【００１７】加えて、本発明の窒素製造装置は、圧縮，
精製した原料空気を前記主熱交換器を経て前記主蒸留塔
に導く原料空気導入経路と、前記主蒸留塔の下部から減
圧弁及び前記コンデンサー・リボイラーを経て前記補助
蒸留塔の下部に接続された上昇ガス生成経路と、前記主
蒸留塔の下部から減圧弁を経て前記補助蒸留塔の上部に
接続された還流液導入経路と、前記補助蒸留塔の下部か
ら減圧弁を経て前記コンデンサー・リボイラーを通り、
前記主熱交換器を経て前記寒冷タービン及び前記駆動タ
ービンに接続された酸素富化ガス導出経路と、前記寒冷
タービン及び前記駆動タービンから熱交換器を経て導出
する寒冷回収経路と、前記補助蒸留塔の上部から前記循
環圧縮機を通り、前記主熱交換器を経て前記主蒸留塔の
下部に接続された窒素富化ガス循環導入経路とを備えて
いることを特徴とし、前記窒素富化ガス循環導入経路が
前記原料空気導入経路に合流して前記主蒸留塔の下部に
接続されていることを特徴としている。In addition, the nitrogen production apparatus of the present invention
A raw material air introduction path for guiding the purified raw air to the main distillation column through the main heat exchanger, and a lower part of the main distillation column connected to a lower part of the auxiliary distillation column through a pressure reducing valve and the condenser / reboiler. Ascending gas generation path, reflux liquid introduction path connected to the upper part of the auxiliary distillation column from the lower part of the main distillation column via a pressure reducing valve, and passing through the condenser reboiler via the pressure reducing valve from the lower part of the auxiliary distillation column. ,
An oxygen-enriched gas outlet path connected to the cold turbine and the drive turbine via the main heat exchanger, a cold recovery path led out of the cold turbine and the drive turbine via a heat exchanger, and the auxiliary distillation column And a nitrogen-enriched gas circulation introduction path connected to the lower part of the main distillation column through the circulating compressor from the upper part through the main heat exchanger. An introduction path joins the raw air introduction path and is connected to a lower portion of the main distillation column.
【００１８】[0018]
【発明の実施の形態】図１は本発明の一形態例を示す系
統図である。以下、この窒素製造装置により窒素を製造
するプロセスに基づいて本発明をさらに詳細に説明す
る。FIG. 1 is a system diagram showing one embodiment of the present invention. Hereinafter, the present invention will be described in more detail based on a process for producing nitrogen by the nitrogen producing apparatus.
【００１９】まず、５６９２Ｎｍ３／ｈの原料空気は、
経路６１を通り、原料空気圧縮機５１で７．７ｋｇ／ｃ
ｍ２ａｂｓ．に圧縮され、アフタークーラー５１ａで４
０℃に冷却された後、前処理設備５２で二酸化炭素及び
水分等の不純物が吸着・除去されて精製される。この精
製原料空気は、経路６２を通り、主熱交換器５３で露点
温度付近まで冷却された後、原料空気導入経路を構成す
る経路６３を通って主蒸留塔５４の下部に導入される。First, the raw material air of 5,692 Nm 3 / h is
Passing the path 61, 7.7 kg / c by the raw material air compressor 51
m 2 abs. Compressed by the after cooler 51a
After cooling to 0 ° C., impurities such as carbon dioxide and moisture are adsorbed and removed in the pretreatment facility 52 and purified. This purified raw air passes through a path 62 and is cooled to a temperature near the dew point in a main heat exchanger 53, and then is introduced into a lower portion of a main distillation column 54 through a path 63 constituting a raw air introduction path.
【００２０】主蒸留塔５４では、塔内を上昇するガスと
頂部のリボイラー／コンデンサー５５で凝縮して塔内を
下降する液との気液接触によって蒸留が行われ、頂部か
ら窒素ガス、底部から酸素濃度３６％の酸素富化液化空
気が抜き出される。In the main distillation column 54, distillation is performed by gas-liquid contact between the gas rising in the column and the liquid condensing in the reboiler / condenser 55 at the top and descending in the column, and nitrogen gas from the top and nitrogen gas from the bottom. An oxygen-enriched liquefied air with an oxygen concentration of 36% is withdrawn.
【００２１】塔頂部の経路６４に抜き出された窒素ガス
のうち、３０００Ｎｍ３／ｈが経路６６に分岐し、過冷
器５６，経路６７，主熱交換器５３を通って昇温され
る。この窒素ガスは、経路６８を通り，７．３ｋｇ／ｃ
ｍ２ａｂｓ．、３６℃で抜き出され、酸素濃度０．１ｐ
ｐｂ以下の製品窒素ガスＧＮとして回収される。3000 Nm 3 / h of the nitrogen gas extracted to the passage 64 at the top of the tower branches to the passage 66, and is heated through the subcooler 56, the passage 67, and the main heat exchanger 53. This nitrogen gas passes through path 68 and is 7.3 kg / c
m 2 abs. Extracted at 36 ° C, oxygen concentration 0.1p
It is recovered as a product nitrogen gas GN of pb or less.
【００２２】経路６４の残りの窒素ガスは、リボイラー
／コンデンサー５５に導入され、主蒸留塔５４から抜き
出された酸素富化液化空気及び後述の補助蒸留塔５７か
ら抜き出された酸素富化液と熱交換することによって凝
縮液化し、経路６５から主蒸留塔５４の頂部に還流液と
して戻される。The remaining nitrogen gas in the passage 64 is introduced into the reboiler / condenser 55, where the oxygen-enriched liquefied air extracted from the main distillation column 54 and the oxygen-enriched liquid extracted from the auxiliary distillation column 57 to be described later. The liquid is condensed and liquefied by heat exchange with the liquid, and is returned to the top of the main distillation column 54 from the passage 65 as a reflux liquid.
【００２３】主蒸留塔５４の底部から抜き出された３８
４４Ｎｍ３／ｈの酸素富化液化空気は、経路６９を通っ
て過冷器５６で冷却された後、経路７０から２つの経路
に分岐する。上昇ガス生成経路を構成する経路７１に分
岐した９１５Ｎｍ３／ｈの酸素富化液化空気は、リボイ
ラー／コンデンサー５５を通る窒素ガスと適当な温度差
が得られるような圧力（３．６ｋｇ／ｃｍ２ａｂｓ．）
に減圧弁７１ａで減圧された後、経路７２を通ってリボ
イラー／コンデンサー５５に導入されて気化する。この
ガスは、上昇ガス生成経路を構成する経路７３を通り、
補助蒸留塔５７の下部に上昇ガスとして導入される。一
方、前記過冷器５６を導出後に還流液導入経路を構成す
る経路７４に分岐した２９２９Ｎｍ３／ｈの酸素富化液
化空気は、減圧弁７４ａで補助蒸留塔５７の圧力に減圧
され、経路７５から補助蒸留塔５７の塔頂部に還流液と
して供給される。38 extracted from the bottom of the main distillation column 54
The 44-Nm 3 / h oxygen-enriched liquefied air passes through the passage 69 and is cooled by the subcooler 56, and then branches off from the passage 70 into two passages. The 915 Nm 3 / h oxygen-enriched liquefied air branched to the path 71 constituting the ascending gas generation path has a pressure (3.6 kg / cm 2) such that an appropriate temperature difference is obtained with the nitrogen gas passing through the reboiler / condenser 55. abs.)
After the pressure is reduced by the pressure reducing valve 71a, the gas is introduced into the reboiler / condenser 55 through the path 72 and vaporized. This gas passes through a path 73 constituting a rising gas generation path,
The gas is introduced into the lower part of the auxiliary distillation column 57 as a rising gas. On the other hand, the oxygen-enriched liquefied air of 2929 Nm 3 / h branched off to the path 74 constituting the reflux liquid introduction path after the supercooler 56 is drawn out is reduced to the pressure of the auxiliary distillation column 57 by the pressure reducing valve 74 a, and the path 75 Is supplied to the top of the auxiliary distillation column 57 as a reflux liquid.
【００２４】補助蒸留塔５７では、上記上昇ガス及び還
流液による蒸留が行われ、塔頂部からは、１１５２Ｎｍ
３／ｈの空気に近い組成の窒素富化ガスが窒素富化ガス
循環導入経路を構成する経路７６に循環流体として抜き
出され、塔底からは酸素を４４％含む酸素富化液が抜き
出される。補助蒸留塔５７の塔底から抜き出された２６
９２Ｎｍ３／ｈの酸素富化液は、経路８０を通り、リボ
イラー／コンデンサー５５を通る窒素ガスと適当な温度
差が得られる圧力（３．３ｋｇ／ｃｍ２ａｂｓ．）に減
圧弁８０ａで減圧された後、経路８１を通ってリボイラ
ー／コンデンサー５５に導入され、気化して酸素富化ガ
スとなる。In the auxiliary distillation column 57, the above-described distillation using the rising gas and the reflux liquid is performed, and 1152 Nm
3 / h nitrogen-enriched gas having a composition close to air is withdrawn as a circulating fluid through a path 76 constituting a nitrogen-enriched gas circulation introduction path, and an oxygen-enriched liquid containing 44% oxygen is extracted from the bottom of the tower. It is. 26 extracted from the bottom of the auxiliary distillation column 57
The oxygen-enriched liquid of 92 Nm 3 / h passes through the path 80 and is depressurized by the pressure reducing valve 80 a to a pressure (3.3 kg / cm 2 abs.) At which an appropriate temperature difference is obtained with the nitrogen gas passing through the reboiler / condenser 55. After that, the gas is introduced into the reboiler / condenser 55 through a path 81 and is vaporized to become an oxygen-enriched gas.
【００２５】この酸素富化ガスは、酸素富化ガス導出経
路を構成する経路８２を通り、過冷器５６で昇温した
後、経路８３を通って主熱交換器５３で−１４３℃に昇
温した時点で経路８４に流出し、ここで２つの経路に分
岐する。一方の経路８５を通る１００８Ｎｍ３／ｈの酸
素富化ガスは、プロセスに寒冷を供給するため、寒冷タ
ービン５８で１．３ｋｇ／ｃｍ２ａｂｓ．に減圧されて
経路８６に導出される。一方、経路８７に分岐した残部
の酸素富化ガスは、後述する循環圧縮機６０と連結した
駆動タービン５９で１．３ｋｇ／ｃｍ２ａｂｓ．に減圧
され、動力を発生して経路８８に導出される。経路８６
及び経路８８の酸素富化ガスは、寒冷回収経路を構成す
る経路８９に合流し、主熱交換器５３で原料空気と熱交
換することにより寒冷が回収されて３６℃に昇温し、経
路９０を通って廃ガスＷＧとして抜き出され、その一部
が前処理設備５３の再生に利用される。This oxygen-enriched gas passes through a route 82 constituting an oxygen-enriched gas outlet route, is heated in a subcooler 56, and then passes through a route 83 to a temperature of -143 ° C. in a main heat exchanger 53. When heated, it flows out to the path 84, where it branches into two paths. 1008 Nm 3 / h of oxygen-enriched gas passing through one path 85 is supplied to the refrigeration turbine 58 at 1.3 kg / cm 2 abs. , And is led out to the path 86. On the other hand, the remaining oxygen-enriched gas branched to the path 87 is supplied to a driving turbine 59 connected to a circulating compressor 60 described later at 1.3 kg / cm 2 abs. , Generating power and being led out to the path 88. Route 86
And the oxygen-enriched gas in the path 88 joins the path 89 constituting the cold recovery path, and exchanges heat with the raw material air in the main heat exchanger 53 to recover the cold and raise the temperature to 36 ° C. The waste gas WG is extracted as waste gas WG, and a part thereof is used for regeneration of the pretreatment equipment 53.
【００２６】前記寒冷タービン５８及び駆動タービン５
９の導入側の酸素富化ガス導出経路を構成する経路８３
と、寒冷タービン５８及び駆動タービン５９の導出側の
寒冷回収経路を構成する経路８９とを接続する経路９１
及び弁９１ａは、両タービン５８，５９に導入する酸素
富化ガスの全部又は一部を両タービン５８，５９をバイ
パスして流すもので、両タービン５８，５９の少なくと
も１つが停止したときや，必要により両タービン５８，
５９の少なくとも１つの流量を調節するときに使用され
る。The cold turbine 58 and the drive turbine 5
Route 83 that constitutes the oxygen-enriched gas outlet route on the introduction side of No. 9
A path 91 that connects the cold turbine 58 and a path 89 that forms a cold recovery path on the outlet side of the drive turbine 59.
And a valve 91a for flowing all or a part of the oxygen-enriched gas introduced into both turbines 58, 59 by bypassing both turbines 58, 59, and when at least one of both turbines 58, 59 is stopped, If necessary, both turbines 58,
It is used when adjusting at least one of the 59 flow rates.
【００２７】補助蒸留塔５７の頂部から窒素富化ガス循
環導入経路を構成する経路７６に抜き出された循環流体
としての窒素富化ガスは、過冷器５６で昇温して経路７
７を通り、循環圧縮機６０で圧縮される。圧縮された窒
素富化ガスは、窒素富化ガス循環導入経路を構成する経
路７８を通り、主熱交換器５３で冷却された後、経路７
９を通って主蒸留塔５４の下部に循環導入される。The nitrogen-enriched gas as a circulating fluid extracted from the top of the auxiliary distillation column 57 to a path 76 constituting a nitrogen-enriched gas circulation introduction path is heated by a subcooler 56 to a path 7.
7 and compressed by the circulation compressor 60. The compressed nitrogen-enriched gas passes through a path 78 constituting a nitrogen-enriched gas circulation introduction path, and is cooled by the main heat exchanger 53.
9 and is circulated into the lower portion of the main distillation column 54.
【００２８】低温圧縮機６０は、前述した駆動タービン
５９と同軸上に接続されており、駆動タービン５９によ
って発生した動力を利用して駆動されている。The low-temperature compressor 60 is coaxially connected to the drive turbine 59 described above, and is driven by using the power generated by the drive turbine 59.
【００２９】このように、本形態例によれば、前記図２
に示した従来プロセスに比べて酸素含有量の少ない窒素
富化ガスを主蒸留塔５４に循環導入するから、主蒸留塔
５４から経路６９に抜き出す酸素富化液化空気中の酸素
含有量も少なくなる。したがって、リボイラー／コンデ
ンサー５５で酸素富化液化空気を気化させるとき、酸素
含有量が少ない分、気化圧力を約０．３ｋｇ／ｃｍ２高
くすることができる。これにより、酸素富化ガス導出経
路を構成する経路８２を通る酸素富化ガスの圧力よりも
循環流体の圧力を高くすることができ、低温圧縮機６０
に導入する窒素富化ガスの吸入圧力も高くできるため、
循環圧縮機６０の圧縮比が小さくとれ、主蒸留塔５４に
循環導入する循環流体の流量を増加させることができ、
窒素の製造原単位を低減することができる。As described above, according to the present embodiment, FIG.
Since the nitrogen-enriched gas having a low oxygen content is circulated and introduced into the main distillation column 54 as compared with the conventional process shown in (1), the oxygen content in the oxygen-enriched liquefied air extracted from the main distillation column 54 to the path 69 is also reduced. . Therefore, when the oxygen-enriched liquefied air is vaporized by the reboiler / condenser 55, the vaporization pressure can be increased by about 0.3 kg / cm 2 due to the small oxygen content. Thereby, the pressure of the circulating fluid can be made higher than the pressure of the oxygen-enriched gas passing through the path 82 constituting the oxygen-enriched gas deriving path, and the low-temperature compressor 60
To increase the suction pressure of the nitrogen-enriched gas introduced into the
The compression ratio of the circulating compressor 60 can be reduced, and the flow rate of the circulating fluid circulated into the main distillation column 54 can be increased.
Nitrogen production intensity can be reduced.
【００３０】すなわち、循環圧縮機６０の入口圧力は、
これに導入する流体のリボイラー／コンデンサー５５に
おける気化圧力に依存する。この圧力は、リボイラー／
コンデンサー５５を通る窒素ガスとの温度差が適当にな
るように決定され、この流体の組成に依存する。つま
り、主蒸留塔５４の底部から抜き出した酸素富化液化空
気は、補助蒸留塔５７の底部から抜き出した酸素富化液
と比較して酸素濃度が低いため、リボイラー／コンデン
サー５５で気化させる際の圧力を高くすることができ
る。さらに、この気化ガスは、補助蒸留塔５７に導入さ
れるため、補助蒸留塔５７の頂部から抜き出す循環流体
の圧力を高くすることができる。しかも、循環圧縮機６
０は、駆動タービン５９によって駆動されているので、
入口圧力が高くなれば吸入量が増加する。これは、循環
量の増加につながり、主蒸留塔５４における上昇ガス量
及び下降液量が増加し、結果として製品窒素の回収率が
増加し、窒素の製造原単位を低減することができる。That is, the inlet pressure of the circulating compressor 60 is
It depends on the vaporization pressure of the fluid introduced in the reboiler / condenser 55. This pressure is equal to the reboiler /
The temperature difference with the nitrogen gas passing through the condenser 55 is determined to be appropriate and depends on the composition of this fluid. That is, since the oxygen-enriched liquefied air extracted from the bottom of the main distillation column 54 has a lower oxygen concentration than the oxygen-enriched liquid extracted from the bottom of the auxiliary distillation column 57, the oxygen-enriched liquefied air is vaporized by the reboiler / condenser 55. Pressure can be increased. Further, since the vaporized gas is introduced into the auxiliary distillation column 57, the pressure of the circulating fluid extracted from the top of the auxiliary distillation column 57 can be increased. Moreover, the circulation compressor 6
0 is driven by the drive turbine 59,
As the inlet pressure increases, the suction volume increases. This leads to an increase in the amount of circulation, and an increase in the amount of rising gas and the amount of descending liquid in the main distillation column 54. As a result, the recovery rate of product nitrogen increases, and the unit production of nitrogen can be reduced.
【００３１】本形態例におけるコンデンサー・リボイラ
ー５５には、液浸漬型ではなく、ドライタイプを使用し
ている。本形態例のように、冷流体が２流体ある場合に
浸漬型のコンデンサー・リボイラーを使用すると、冷流
体の液中にコンデンサー・リボイラーを浸す必要がある
ため、２つのコンデンサー・リボイラーを設置すること
が必須となる。しかし、ドライタイプの場合には、液中
に浸す必要がないため、冷流体の流路を２流路に構成す
ることによって、容易に一体化ができる。但し、コンデ
ンサー・リボイラー５５は、主蒸留塔５４からの酸素富
化液化空気を気化させるものと、補助蒸留塔５７からの
酸素富化液を気化させるものと、別々に構成してもよ
い。さらに、液浸漬型の場合は、気化側の液体が液ヘッ
ドにより過冷却となり、この分、気化圧力を低くしなけ
ればならないが、ドライタイプの場合は、このようなこ
とがないので、気化圧力を高めることができる。さらに
また、液浸漬型に比べて保有液量が少ないので、装置の
起動時間を短縮する効果もある。As the condenser / reboiler 55 in this embodiment, a dry type is used instead of a liquid immersion type. As in this embodiment, when using a immersion type condenser / reboiler when there are two cold fluids, it is necessary to immerse the condenser / reboiler in the liquid of the cold fluid. Is required. However, in the case of the dry type, since it is not necessary to immerse the liquid in the liquid, it is possible to easily integrate the cold fluid by forming the flow path of the cold fluid into two flow paths. However, the condenser / reboiler 55 may be configured separately from one that vaporizes the oxygen-enriched liquefied air from the main distillation column 54 and one that vaporizes the oxygen-enriched liquid from the auxiliary distillation column 57. Furthermore, in the case of the liquid immersion type, the liquid on the vaporization side is supercooled by the liquid head, and the vaporization pressure must be reduced accordingly.However, in the case of the dry type, the vaporization pressure does not occur. Can be increased. Furthermore, since the amount of the retained liquid is smaller than that of the liquid immersion type, there is also an effect of shortening the startup time of the apparatus.
【００３２】また、本形態例では、補助蒸留塔５７にお
ける蒸留により、その塔頂から抜き出す窒素富化ガス中
の窒素濃度を空気中の窒素濃度より高くできるため、こ
れを圧縮して主蒸留塔５４に循環導入するに際し、この
循環流体と同じ組成の塔内上昇ガスの精留段の位置、す
なわち、原料空気の供給段より少なくとも１平衡段上
に、好ましくは４平衡段上に供給することが望ましい
が、循環圧縮機６０から経路７８に導出する循環流体
を、主熱交換器５３の原料空気導入通路の原料空気と合
流させるようにしてもよい。これにより、循環流体の流
路や主熱交換器５３の流路を減らすことができるため、
設備費を削減することができる。In the present embodiment, the nitrogen concentration in the nitrogen-enriched gas extracted from the top of the auxiliary distillation column 57 can be made higher than the nitrogen concentration in the air by distillation in the auxiliary distillation column 57. When the gas is circulated into the column 54, it is supplied to the position of the rectification stage of the ascending gas in the column having the same composition as that of the circulating fluid, that is, at least one equilibrium stage, preferably four equilibrium stages, from the feed stage of the raw air. However, the circulating fluid derived from the circulating compressor 60 to the passage 78 may be combined with the raw air in the raw air introduction passage of the main heat exchanger 53. Thereby, the flow path of the circulating fluid and the flow path of the main heat exchanger 53 can be reduced,
Equipment costs can be reduced.
【００３３】また、主蒸留塔５４から抜き出す酸素富化
液化空気を減圧する前に、過冷器５６において、主蒸留
塔５４からの窒素ガス，補助蒸留塔５７からの窒素富化
ガス及びコンデンサー・リボイラー５５からの酸素富化
ガスで過冷却することにより、コンデンサー・リボイラ
ー５５での冷却源としての温度を低めることができると
ともに、経路７５から補助蒸留塔５７に導入する還流液
の減圧によるフラッシュロスを低減でき、補助蒸留塔５
７における精留効率を高めることができる。Before the oxygen-enriched liquefied air extracted from the main distillation column 54 is decompressed, the nitrogen gas from the main distillation column 54, the nitrogen-enriched gas from the auxiliary distillation column 57 and the condenser By subcooling with the oxygen-enriched gas from the reboiler 55, the temperature as a cooling source in the condenser reboiler 55 can be lowered, and the flash loss due to the reduced pressure of the reflux liquid introduced into the auxiliary distillation column 57 from the passage 75 is reduced. And the auxiliary distillation column 5
7, the rectification efficiency can be increased.
【００３４】さらに、循環圧縮機６０での循環ガスの圧
縮は、本形態例で示したように、低温蒸留温度で行って
もよいし、主熱交換器５３で適当な温度まで昇温した後
に圧縮することもでき、設計条件により、蒸留低温レベ
ルから常温までの間の温度を任意に選択することができ
る。Further, the compression of the circulating gas in the circulating compressor 60 may be performed at a low-temperature distillation temperature as shown in the present embodiment, or after the temperature is raised to an appropriate temperature in the main heat exchanger 53. Compression can also be performed, and the temperature between the low-temperature distillation level and room temperature can be arbitrarily selected depending on design conditions.
【００３５】また、主蒸留塔５４と補助蒸留塔５７の少
なくとも１つに充填物を使用することにより、蒸留塔の
圧力損失を少なくすることができるので、さらに窒素製
造原単位を低下させることができる。Further, by using a packing for at least one of the main distillation column 54 and the auxiliary distillation column 57, the pressure loss of the distillation column can be reduced, so that the nitrogen production unit can be further reduced. it can.
【００３６】本形態例によれば、窒素回収率を約５３
％、窒素動力原単位（製品窒素流量に対する全動力の
比）を０．２４７ｋＷｈ／Ｎｍ３にできる。同条件で計
算を行った前記図２の従来プロセスと比較し、動力原単
位を０．０２ｋＷｈ／Ｎｍ３減少することが可能とな
る。According to this embodiment, the nitrogen recovery rate is about 53
%, The nitrogen power consumption unit (the ratio of the total power to the product nitrogen flow rate) can be set to 0.247 kWh / Nm 3 . As compared with the conventional process of FIG. 2 calculated under the same conditions, the power consumption can be reduced by 0.02 kWh / Nm 3 .
【００３７】[0037]
【発明の効果】以上説明したように、本発明によれば、
補助蒸留塔での蒸留によって循環ガスの窒素濃度を上げ
ることができるとともに、各気液の組成の改善によって
主蒸留塔に循環させるガスを増量できるので、動力の増
加を極力抑えながら窒素回収率を向上させて窒素の製造
原単位を低減することができる。As described above, according to the present invention,
The nitrogen concentration of the circulating gas can be increased by distillation in the auxiliary distillation column, and the amount of gas circulated to the main distillation column can be increased by improving the composition of each gas and liquid, so that the nitrogen recovery rate can be reduced while minimizing the increase in power. It is possible to reduce the production unit of nitrogen by improving.
【図１】 本発明の一形態例を示す窒素製造装置の系統
図である。FIG. 1 is a system diagram of a nitrogen production apparatus showing one embodiment of the present invention.
【図２】 従来プロセスの一例を示す系統図である。FIG. 2 is a system diagram showing an example of a conventional process.
５１…原料空気圧縮機、５２…前処理設備、５３…主熱
交換器、５４…主蒸留塔、５５…リボイラー／コンデン
サー、５６…過冷器、５７…補助蒸留塔、５８…寒冷タ
ービン、５９…駆動タービン、６０…循環圧縮機51: Raw material air compressor, 52: Pretreatment equipment, 53: Main heat exchanger, 54: Main distillation column, 55: Reboiler / condenser, 56: Subcooler, 57: Auxiliary distillation column, 58: Cold turbine, 59 ... Drive turbine, 60 ... Circulation compressor
Claims (13)
塔に導入して低温蒸留し、酸素富化液化空気と窒素ガス
とに分離して分離した窒素ガスを製品として採取する窒
素製造方法において、前記酸素富化液化空気の一部を減
圧後に前記窒素ガスと熱交換させて気化し、補助蒸留塔
に導入するとともに、前記酸素富化液化空気の残部を減
圧して前記補助蒸留塔に導入し、該補助蒸留塔での蒸留
により酸素富化液と窒素富化ガスとに分離し、前記酸素
富化液を減圧後に前記窒素ガスと熱交換させて気化する
ことにより酸素富化ガスを生成し、生成した酸素富化ガ
スを膨張させるとともに、前記窒素富化ガスを圧縮して
前記主蒸留塔に循環導入することを特徴とする窒素製造
方法。1. A nitrogen production method wherein compressed, purified, and cooled raw material air is introduced into a main distillation column, subjected to low-temperature distillation, separated into oxygen-enriched liquefied air and nitrogen gas, and the separated nitrogen gas is collected as a product. In the above, a part of the oxygen-enriched liquefied air is vaporized by heat exchange with the nitrogen gas after decompression, and introduced into the auxiliary distillation column, and the remaining oxygen-enriched liquefied air is decompressed to the auxiliary distillation column. Introduced, separated into an oxygen-enriched liquid and a nitrogen-enriched gas by distillation in the auxiliary distillation column, and the oxygen-enriched liquid is decompressed and then heat-exchanged with the nitrogen gas to vaporize the oxygen-enriched gas. A method for producing nitrogen, wherein the produced and enriched oxygen-enriched gas is expanded, and the nitrogen-enriched gas is compressed and circulated into the main distillation column.
留塔に導入する原料空気の導入位置より少なくとも１理
論段上から主蒸留塔に導入することを特徴とする請求項
１記載の窒素製造方法。2. The nitrogen according to claim 1, wherein the compressed nitrogen-enriched gas is introduced into the main distillation column from at least one theoretical stage above a position where the feed air introduced into the main distillation column is introduced. Production method.
留塔に導入する前の原料空気に混合することを特徴とす
る請求項１記載の窒素製造方法。3. The method for producing nitrogen according to claim 1, wherein the compressed nitrogen-enriched gas is mixed with raw air before being introduced into the main distillation column.
が、蒸留温度レベルから常温までの範囲であることを特
徴とする請求項１記載の窒素製造方法。4. The method for producing nitrogen according to claim 1, wherein the temperature before compressing the nitrogen-enriched gas ranges from a distillation temperature level to a normal temperature.
酸素富化液化空気を、前記窒素ガス及び前記窒素富化ガ
ス及び前記酸素富化ガスのいずれか少なくとも一つで冷
却することを特徴とする請求項１記載の窒素製造方法。5. The method according to claim 1, wherein the oxygen-enriched liquefied air before being decompressed and taken out from the main distillation column is cooled by at least one of the nitrogen gas, the nitrogen-enriched gas and the oxygen-enriched gas. The method for producing nitrogen according to claim 1, wherein:
留することにより窒素を採取する窒素製造装置におい
て、圧縮，精製した原料空気を低温蒸留で得られた低温
戻りガスとの熱交換により冷却する主熱交換器と、冷却
した原料空気を低温蒸留して窒素ガスと酸素富化液化空
気とに分離する主蒸留塔と、前記主蒸留塔で得られた酸
素富化液化空気の一部を減圧・気化した後に上昇ガスと
して導入するとともに、前記主蒸留塔で得られた酸素富
化液化空気の残部を還流液として導入し、低温蒸留して
酸素富化液と窒素富化ガスとに分離する補助蒸留塔と、
前記窒素ガスと前記酸素富化液化空気及び前記酸素富化
液とを熱交換させ、窒素ガスを液化して前記主蒸留塔の
還流液を生成するとともに、酸素富化液化空気及び酸素
富化液を気化するコンデンサー・リボイラーと、該コン
デンサー・リボイラーで酸素富化液を気化して生成した
酸素富化ガスを膨張させて寒冷を発生する寒冷タービン
及び動力を発生する駆動タービンと、前記窒素富化ガス
を圧縮する循環圧縮機とを備えたことを特徴とする窒素
製造装置。6. A nitrogen production apparatus for collecting nitrogen by compressing, purifying, cooling and cryogenic distillation of raw air, wherein the compressed and purified raw air is subjected to heat exchange with a low-temperature return gas obtained by cryogenic distillation. A main heat exchanger for cooling, a main distillation column for low-temperature distillation of the cooled raw material air to separate it into nitrogen gas and oxygen-enriched liquefied air, and a part of the oxygen-enriched liquefied air obtained in the main distillation column Is introduced as an ascending gas after decompression and vaporization, and the remainder of the oxygen-enriched liquefied air obtained in the main distillation column is introduced as a reflux liquid, and is subjected to low-temperature distillation into an oxygen-enriched liquid and a nitrogen-enriched gas. An auxiliary distillation column to separate,
The nitrogen gas is subjected to heat exchange with the oxygen-enriched liquefied air and the oxygen-enriched liquid to liquefy the nitrogen gas to generate a reflux liquid of the main distillation column, and the oxygen-enriched liquefied air and the oxygen-enriched liquid A condenser reboiler, a cooling turbine for generating cold by expanding an oxygen-enriched gas generated by vaporizing an oxygen-enriched liquid with the condenser reboiler, and a drive turbine for generating power, and the nitrogen enrichment. A nitrogen production device comprising: a circulation compressor for compressing gas.
くとも一つが充填式蒸留塔であることを特徴とする請求
項６記載の窒素製造装置。7. The nitrogen production apparatus according to claim 6, wherein at least one of said main distillation column and said auxiliary distillation column is a packed distillation column.
イタイプであることを特徴とする請求項６記載の窒素製
造装置。8. The nitrogen production apparatus according to claim 6, wherein said condenser / reboiler is of a dry type.
酸素富化液化空気を気化させるものと、前記酸素富化液
を気化させるものとに分割して別々に構成されているこ
とを特徴とする請求項６記載の窒素製造装置。9. The condenser reboiler according to claim 1, wherein the condenser reboiler is divided into a part for vaporizing the oxygen-enriched liquefied air and a part for vaporizing the oxygen-enriched liquid. 7. The nitrogen production apparatus according to 6.
あることを特徴とする請求項６記載の窒素製造装置。10. The nitrogen production apparatus according to claim 6, wherein said circulating compressor is of a low temperature specification.
又は駆動タービンと同軸上に連結して構成されているこ
とを特徴とする請求項６記載の窒素製造装置。11. The nitrogen production apparatus according to claim 6, wherein the circulating compressor is configured to be coaxially connected to the cooling turbine or the driving turbine.
換器を経て前記主蒸留塔に導く原料空気導入経路と、前
記主蒸留塔の下部から減圧弁及び前記コンデンサー・リ
ボイラーを経て前記補助蒸留塔の下部に接続された上昇
ガス生成経路と、前記主蒸留塔の下部から減圧弁を経て
前記補助蒸留塔の上部に接続された還流液導入経路と、
前記補助蒸留塔の下部から減圧弁を経て前記コンデンサ
ー・リボイラーを通り、前記主熱交換器を経て前記寒冷
タービン及び前記駆動タービンに接続された酸素富化ガ
ス導出経路と、前記寒冷タービン及び前記駆動タービン
から熱交換器を経て導出する寒冷回収経路と、前記補助
蒸留塔の上部から前記循環圧縮機を通り、前記主熱交換
器を経て前記主蒸留塔の下部に接続された窒素富化ガス
循環導入経路とを備えていることを特徴とする請求項６
記載の窒素製造装置。12. A feed air introduction path for leading compressed and purified feed air to the main distillation column through the main heat exchanger, and the auxiliary distillation from a lower portion of the main distillation column through a pressure reducing valve and the condenser reboiler. An ascending gas generation path connected to the lower part of the column, and a reflux liquid introduction path connected to the upper part of the auxiliary distillation column via a pressure reducing valve from the lower part of the main distillation column,
An oxygen-enriched gas lead-out path connected from the lower part of the auxiliary distillation column to the cold turbine and the drive turbine through the condenser reboiler through the pressure reducing valve, the main heat exchanger, and the cold turbine and the drive A cold recovery path derived from a turbine via a heat exchanger, and a nitrogen-enriched gas circulation connected to the lower part of the main distillation column through the main heat exchanger, through the circulating compressor from the upper part of the auxiliary distillation column. 7. An introduction path.
The nitrogen production apparatus as described in the above.
記原料空気導入経路に合流して前記主蒸留塔の下部に接
続されていることを特徴とする請求項１２記載の窒素製
造装置。13. The nitrogen production apparatus according to claim 12, wherein the nitrogen-enriched gas circulation introduction path joins the feed air introduction path and is connected to a lower portion of the main distillation column.
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|---|---|---|---|
| JP17598598A JP4150107B2 (en) | 1998-06-23 | 1998-06-23 | Nitrogen production method and apparatus |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP17598598A JP4150107B2 (en) | 1998-06-23 | 1998-06-23 | Nitrogen production method and apparatus |
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| JP4150107B2 JP4150107B2 (en) | 2008-09-17 |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2008112556A2 (en) * | 2007-03-09 | 2008-09-18 | Praxair Technology, Inc. | Nitrogen production method and apparatus |
| CN105222525A (en) * | 2015-10-29 | 2016-01-06 | 西亚特工业气体科技（杭州）有限公司 | The preparation facilities of oxygen-enriched air product and method |
| WO2020083525A1 (en) * | 2018-10-23 | 2020-04-30 | Linde Aktiengesellschaft | Method and unit for low-temperature air separation |
| CN115451610A (en) * | 2022-09-07 | 2022-12-09 | 安徽正刚新能源科技有限公司 | Heat recovery water medium multistage compression ultrahigh-temperature heat pump system |
-
1998
- 1998-06-23 JP JP17598598A patent/JP4150107B2/en not_active Expired - Fee Related
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2008112556A2 (en) * | 2007-03-09 | 2008-09-18 | Praxair Technology, Inc. | Nitrogen production method and apparatus |
| WO2008112556A3 (en) * | 2007-03-09 | 2008-12-24 | Praxair Technology Inc | Nitrogen production method and apparatus |
| CN101285640B (en) * | 2007-03-09 | 2012-07-11 | 普莱克斯技术有限公司 | Nitrogen production method and apparatus |
| CN105222525A (en) * | 2015-10-29 | 2016-01-06 | 西亚特工业气体科技（杭州）有限公司 | The preparation facilities of oxygen-enriched air product and method |
| WO2020083525A1 (en) * | 2018-10-23 | 2020-04-30 | Linde Aktiengesellschaft | Method and unit for low-temperature air separation |
| CN115451610A (en) * | 2022-09-07 | 2022-12-09 | 安徽正刚新能源科技有限公司 | Heat recovery water medium multistage compression ultrahigh-temperature heat pump system |
| CN115451610B (en) * | 2022-09-07 | 2024-02-27 | 安徽正刚新能源科技有限公司 | Heat recovery water medium multistage compression ultra-high temperature heat pump system |
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| JP4150107B2 (en) | 2008-09-17 |
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