JP3694343B2 - PSA for low concentration oxygen - Google Patents
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- JP3694343B2 JP3694343B2 JP13267995A JP13267995A JP3694343B2 JP 3694343 B2 JP3694343 B2 JP 3694343B2 JP 13267995 A JP13267995 A JP 13267995A JP 13267995 A JP13267995 A JP 13267995A JP 3694343 B2 JP3694343 B2 JP 3694343B2
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- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 title claims description 165
- 239000001301 oxygen Substances 0.000 title claims description 159
- 229910052760 oxygen Inorganic materials 0.000 title claims description 159
- 238000001179 sorption measurement Methods 0.000 claims description 157
- 238000000034 method Methods 0.000 claims description 150
- 230000008569 process Effects 0.000 claims description 132
- 238000010926 purge Methods 0.000 claims description 71
- 239000007789 gas Substances 0.000 claims description 62
- 239000003463 adsorbent Substances 0.000 claims description 27
- 238000004519 manufacturing process Methods 0.000 claims description 16
- 238000003795 desorption Methods 0.000 claims description 14
- 239000002994 raw material Substances 0.000 claims description 11
- 238000004140 cleaning Methods 0.000 claims description 10
- 238000005406 washing Methods 0.000 claims description 8
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 10
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 10
- 230000000052 comparative effect Effects 0.000 description 9
- 229910001882 dioxygen Inorganic materials 0.000 description 9
- 238000002485 combustion reaction Methods 0.000 description 8
- 238000000926 separation method Methods 0.000 description 6
- 229910021536 Zeolite Inorganic materials 0.000 description 5
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 5
- 229910052757 nitrogen Inorganic materials 0.000 description 5
- 239000010457 zeolite Substances 0.000 description 5
- 239000012528 membrane Substances 0.000 description 4
- 239000002808 molecular sieve Substances 0.000 description 4
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 description 4
- 230000006837 decompression Effects 0.000 description 3
- 238000007865 diluting Methods 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- 229910000831 Steel Inorganic materials 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 238000003915 air pollution Methods 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 238000010790 dilution Methods 0.000 description 2
- 239000012895 dilution Substances 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 238000007670 refining Methods 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 238000004056 waste incineration Methods 0.000 description 2
- 208000019901 Anxiety disease Diseases 0.000 description 1
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 239000002250 absorbent Substances 0.000 description 1
- 230000002745 absorbent Effects 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000036506 anxiety Effects 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000000567 combustion gas Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000000855 fermentation Methods 0.000 description 1
- 230000004151 fermentation Effects 0.000 description 1
- 239000002440 industrial waste Substances 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000008929 regeneration Effects 0.000 description 1
- 238000011069 regeneration method Methods 0.000 description 1
- 239000000741 silica gel Substances 0.000 description 1
- 229910002027 silica gel Inorganic materials 0.000 description 1
- -1 steel refining Chemical compound 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/10—Process efficiency
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- Separation Of Gases By Adsorption (AREA)
- Oxygen, Ozone, And Oxides In General (AREA)
- Solid-Sorbent Or Filter-Aiding Compositions (AREA)
Description
【０００１】
【産業上の利用分野】
本発明は、モレキュラーシーブなどの吸着剤を使用して、空気から圧力変動吸着法（ＰＳＡ）により低濃度の酸素富化空気を効率的に製造するための操業方法及びそのための装置に関する。
【０００２】
【従来の技術】
従来工業的設備での酸素富化空気を製造する最も経済的な方法は、オンサイトの低温液化空気分離装置で製造した酸素を空気で希釈して用いる方法といわれてきたが、それにもかかわらずこの方法は極めて大型のプラントに限られるだけでなく、総合的な費用は比較的高く、酸素富化空気を使用して燃焼炉の効率を増大したり、大気汚染の低減を図るために採用するにはコスト的に高価になり採用に大きな影響を与えている。
【０００３】
これに対し、１９７０年代にＰＳＡ法が開発され、比較的小型の装置においても酸素の製造が容易にできるようになり、小型の酸素発生装置により酸素富化空気の供給が可能となって酸素富化空気の利用分野が大幅に拡張された。特に最近に至りＰＳＡによる酸素製造方法は技術的に目覚ましい発達を遂げ、低温液化分離装置の領域といわれてきた規模の大型の分野への進出が可能となって来ている。特にその安い建設コスト及びランニングコスト、立ち上がり時間が極めて短いこと、保守管理の容易さなどの点から低温液化酸素分離装置の代替さえ行われつつあるのが現状である。これらのＰＳＡの開発の経緯を観察してみると、高純度酸素発生におけるエネルギー効率の向上を目的としたものに限られ、酸素濃度のより高純度のものが目的とされた方法が主であって、製造された酸素富化空気（通常は酸素濃度９０〜９３％位）は必要以上に高純度であるときは、使用分野によっては製造された高純度の酸素富化空気を空気により薄めて使用している場合さえあった。
【０００４】
さらに酸素富化空気の製造のための他の方法として透過膜の利用方法がある。この膜利用システムは簡単でかつ３０〜４０％の低濃度の酸素が製造できる。装置自体も簡単で比較的少量の需要分野には極めて優れた方法と思われる。このようないくつかの方法があるが大規模の酸素需要分野には主に空気液化分離法が採用されてきた。
現在の使用状況を見てみると、例えば大型の燃焼炉において、酸素富化した空気を燃焼に使用することによって燃焼温度を高め、燃焼効率を増大させ、あるいは大気汚染の低減に寄与させようとしている産業は多い。このような目的においては、一般には９９．５％以上の液体酸素を現場の貯蔵タンクに輸送し、燃焼温度の調整や燃焼炉壁耐火物のライフの延長を図るため、空気を混合して所望の低濃度の酸素富化空気を製造したり、あるいは空気で燃焼している燃焼炉に高純度酸素を追加的に吹く込むなどの方法が取られている。特に酸素の需要量が多い大型の装置の場合にはコストの低減のために液体空気の輸送に変えて現場に低温空気分離装置を設置し高純度の酸素の製造をすることが行われていた。
【０００５】
しかしエネルギー効率からは、いったん高純度の酸素を製造し、使用に際しこれを空気で希釈して使用することは意味がないことであり、初めから希望する酸素濃度の酸素富化空気を製造されることが望ましいことは言うまでもない。この目的からすれば酸素濃度が５０ｖｏｌ％未満の低濃度の酸素富化空気の場合には製造される酸素富化空気の酸素濃度的には透過膜法が好適であるが、現在のところ該方法の設備コストは非常に高く、また透過膜のライフに不安があるなどの理由から有利な方法とは言えない状態にある。また空気液化分離法は、液体空気の製造を経て行う関係から、希望する５０ｖｏｌ％未満のごとき低濃度の酸素富化空気の製造をすることは意味のないものであって、このようなものを直接製造してもエネルギー効率の向上は望めないものである。さらにＰＳＡ法においてもいまだに低濃度の酸素富化空気のためのエネルギー効率の高い操業プロセスあるいはそのための装置についての開発は行われていなかった。
【０００６】
【発明が解決しようとする課題】
本発明は、低濃度の酸素富化空気、特に大型の装置においても利用可能である５０ｖｏｌ％以下の酸素濃度を有する酸素富化空気を製造酸素あたりのエネルギー効率を極めて良く製造できるＰＳＡシステムの操業方法及びそのための製造装置の開発を目的とする。
【０００７】
【課題を解決するための手段】
本発明は、
［１］ 吸着塔が３塔からなる低濃度の酸素富化空気を製造する圧力変動吸着法（ＰＳＡ）において、脱着工程の終了した吸着塔の塔内洗浄のためのパージ用ガス及び／または昇圧用のガスとして空気を使用する低濃度酸素用ＰＳＡ、
［２］ 吸着塔が３塔からなる低濃度の酸素富化空気を製造するＰＳＡにおいて、パージ工程の終了した吸着塔の向流による昇圧工程に使用するガスとして空気を使用する低濃度酸素用ＰＳＡ、
［３］ 吸着塔が３塔からなる低濃度の酸素富化空気を製造するＰＳＡにおいて、吸着工程の終了した吸着塔の洗浄のための並流によるパージ工程に使用するガスとして、空気を使用する低濃度酸素用ＰＳＡ、
［４］ 吸着塔が３塔からなる低濃度の酸素富化空気を製造するＰＳＡにおいて、
ａ．第１の塔が吸着操作をしている間にその前段のステップですでに吸着工程を終了した第３の塔の出口端とパージ工程を終えた第２の塔の入口端を連結して均圧操作を行うと同時にパージを終えた第２の塔の出口端から昇圧空気を導入する工程と、
ｂ．引き続き第１の吸着塔が吸着工程にあり、均圧工程を終えた第３の塔入り口端から塔内に残留するガスを放出して減圧を行い、また第２塔の出口端から空気を導入して昇圧を続け、さらに
ｃ．引き続き第１の塔が吸着を行い、第２の塔は引き続き吸着圧に到達するように昇圧を行い、第３の塔は塔入口端より塔出口端に向かって空気を導入して塔内を並流方向に洗浄するパージ工程
からなる工程を第２吸着塔、第３吸着塔に移し順次繰り返し行うことからなる低濃度酸素の製造方法、
［５］ 吸着塔が３塔からなる低濃度の酸素富化空気を製造するＰＳＡにおいて、
ａ．第１の塔が吸着操作をしている間にその前段のステップですでに吸着工程を終了した第３の塔の出口端とパージ工程を終えた第２の塔の出口端を連結して均圧操作を行うと同時にパージを終えた第２の塔の入口端から昇圧空気を導入する工程と、ｂ．引き続き第１の吸着塔が吸着工程にあり、均圧工程を終えた第３の塔入り口端から塔内に残留するガスを放出して減圧を行い、また第２塔の入口端から空気を導入して昇圧を続け、さらに
ｂ．引き続き第１の塔が吸着を行い、第２の塔は引き続き吸着圧に到達するように昇圧を行い、第３の塔は塔出口端より塔入口端に向かって空気を導入して塔内を向流方向に洗浄するパージ工程
からなる工程を第２吸着塔、第３吸着塔に移し順次繰り返し行うことからなる低濃度酸素の製造方法、
［６］ 低濃度の酸素富化空気の酸素濃度が２３〜５０ｖｏｌ％である上記［１］〜［５］の低濃度酸素の製造方法、
［７］ 吸着塔が３塔からなる低濃度の酸素富化空気を製造するＰＳＡ装置において、吸着工程用の原料空気圧縮機、パージ工程後の均圧工程及び昇圧工程のための昇圧空気圧縮機及び塔内洗浄のパージ工程に使用するパージ空気ブロワーを設けてなるＰＳＡ装置、及び
［８］ 吸着工程の終了した吸着塔の塔内洗浄のためのパージ用ガス及び／または昇圧用のガスとして空気を使用し、吸着塔に向流に供給する低濃度酸素用富化空気を製造するＰＳＡ装置において、水分吸着剤を各吸着塔の入口端及び出口端に充填するかまたは水分吸着剤を充填した２塔以上の水分吸着装置を別途設け、パージ工程に使用する空気及び／または昇圧工程に使用する空気を処理できるように配管した低濃度酸素用ＰＳＡ装置、を開発することにより上記の目的を達成した。
【０００８】
本発明で生産する低濃度の酸素富化空気の酸素濃度は、原則的に２３ｖｏｌ％〜５０ｖｏｌ％の酸素富化空気であり、そのためのＰＳＡ装置の基本的な構成は従来使用されているＰＳＡ装置をそのまま使用するかあるいは若干手を加えるだけで使用可能である。また酸素分離のために使用する吸収剤は従来使用されてきたモレキュラーシーブ（ゼオライト）のような窒素あるいは酸素を選択的に吸収できるものであれば使用可能である。
従来のＰＳＡにおいては図５及び図６の例に示すように、脱着工程の終了した吸着塔のパージ工程、その終了後の均圧工程、さらに均圧したのちの昇圧工程のいずれにおいても製品ガス純度を維持する必要性から吸着工程ガス（製品酸素ガス）あるいは吸着工程直後の高純度酸素ガスを用いている。このため吸着塔内の酸素濃度は高く維持でき、そのため製品酸素ガス濃度を高く維持できるがサイクルあたりの製造ガス量は小さくなり、エネルギー効率は低くならざるを得なかった。
【０００９】
本発明の第１の発明は吸着塔が３塔からなるＰＳＡであって、従来のＰＳＡとは異なり、低濃度の酸素富化空気、特に５０ｖｏｌ％以下のような低濃度の酸素富化空気を製造することを目的としており、製造酸素あたりのエネルギー効率を高めるため従来のＰＳＡが製品酸素ガスを使用してきた脱着工程の終了した吸着塔の塔内洗浄のためのパージ用ガス及び／またはパージ工程の後の吸着塔の昇圧用のガスとして空気を使用するところにある。
本発明の第２の発明は、吸着塔は同じく３塔のＰＳＡであってパージ工程の終了した吸着塔の昇圧工程に使用するガスとして空気を使用するものであるが、この空気は吸着塔に対して向流方向から供給するものである。この結果吸着塔出口端に設けられる水分吸着剤あるいは出口側に設けられた水分吸着装置により空気中の水分が吸着され、酸素用の吸着剤の吸水を防止できる。
本発明の第３の発明は、吸着塔が３塔からなる低濃度の酸素富化空気を製造するＰＳＡにおいて、吸着工程の終了した吸着塔の洗浄のためパージ工程に使用するガスとして空気を使用するものであり、この空気は吸着塔に対し並流方向から供給するものである。
【００１０】
本発明のＰＳＡ装置には、空気の供給のために、原料空気圧縮機Ａ、昇圧空気圧縮機Ｂ、パージ空気ブロワーＣを並列的に設け、これらを効率的に働かせることによりエネルギー効率を高く維持しているものであり、特にパージ空気ブロワーＣを設けることによるエネルギー効率の向上は顕著なものがある。
また吸着塔は従来のＰＳＡにおいては一般的に吸着塔に空気を向流方向から供給することはほとんどないが、本発明のステップにおいてはこのような空気の供給方法が可能であるため水分吸着剤を吸着塔の入口端及び出口端に充填するか、または水分吸着剤を充填した水分吸着装置を別途設け、パージ用空気、昇圧用空気を処理できるようにした装置にする。
さらに本発明においては、極めて大型の装置、例えば発電用ボイラー、大型ごみ焼却場、熔解炉など大量の低濃度の酸素富化空気を必要とするような場合においてＰＳＡユニットを複数基設けるような場合には、同一のサイクルで、かつ位相を変えて操業することによりパージ空気ブロワーを共同で複数基例えば３ユニットで１基のパージ空気ブロワーＣを共同で使用する方式を採ることにより設備費を大きく削減可能になる。
【００１１】
以下図面を参照して本発明を詳細に説明する。なおこの図に示すステップは本発明を実施するための単なる例示であってこれに限定されるものではない。
図１のプロセスにおいては、吸着工程の空気は原料空気圧縮機Ａから、均圧工程、パージ工程、昇圧工程のいずれの工程においても使用するガスは空気であり、均圧工程の空気は昇圧空気圧縮機Ｂから供給され、パージ工程の空気はパージ空気ブロワーＣから、昇圧工程の空気は昇圧空気圧縮機Ｂからそれぞれ供給される。
このステップにおいては吸着塔が３塔からなるＰＳＡであり、
ａ．第１の塔が吸着操作をしている間にその前段のステップですでに吸着工程を終了した第３の塔の出口端とパージ工程を終えた第２の塔の入口端を連結して均圧操作を行うと同時にパージを終えた第２の塔の出口端から昇圧空気を導入する工程、
ｂ．引き続き第１の吸着塔が吸着工程にあり、均圧工程を終えた第３の塔入り口端から塔内に残留するガスを放出して減圧を行い、また第２塔の出口端から空気を導入して昇圧を続け、さらに
ｃ．引き続き第１の塔が吸着を行い、第２の塔は引き続き吸着圧に到達するように昇圧を行い、第３の塔は塔入口端より塔出口端に向かって空気を導入して塔内を並流方向に洗浄する工程
からなり、続いてステップ４においてａ．工程の第１吸着塔は第２吸着塔と読み替え、第２吸着塔を第３吸着塔と読み替え、さらに第３吸着塔を第１吸着塔と読み替えることによる次々同様な操作をする工程を順次第２吸着塔、第３吸着塔に繰り返し行うことにより低濃度酸素を製造することからなる。
【００１２】
図２のプロセスにおいては、吸着工程の空気は原料空気圧縮機Ａから、均圧工程、パージ工程、昇圧工程のいずれの工程においても使用するガスは空気であり、均圧工程の空気は昇圧空気圧縮機Ｂから供給され、パージ工程の空気はパージ空気ブロワーＣから、昇圧工程の空気は昇圧空気圧縮機Ｂからそれぞれ供給される。
このステップにおいては吸着塔が３塔からなるＰＳＡであり、
ａ．第１の塔が吸着操作をしている間にその前段のステップですでに吸着工程を終了した第３の塔の出口端とパージ工程を終えた第２の塔の出口端を連結して均圧操作を行うと同時にパージを終えた第２の塔の入口端から昇圧空気を導入する工程と、
ｂ．引き続き第１の吸着塔が吸着工程にあり、均圧工程を終えた第３の塔入り口端から塔内に残留するガスを放出して減圧を行い、また第２塔の入口端から空気を導入して昇圧を続け、さらに
ｃ．引き続き第１の塔が吸着を行い、第２の塔は引き続き吸着圧に到達するように昇圧を行い、第３の塔は塔出口端より塔入口端に向かって空気を導入して塔内を向流方向に洗浄するパージ工程
からなり、続いてステップ４においてａ．工程の第１吸着塔は第２吸着塔と読み替えて次々同様な操作をする工程を順次第２吸着塔、第３吸着塔に繰り返し行うことにより低濃度酸素を製造することからなる。
【００１３】
図３のプロセスにおいては、吸着工程の空気は原料空気圧縮機Ａから、均圧工程、昇圧工程のいずれの工程においても使用するガスは空気であり、パージ工程のガスは吸着工程終了後の減圧ガスを使用している。均圧工程の空気は昇圧空気圧縮機Ｂから供給され、昇圧工程の空気は昇圧空気圧縮機Ｂからそれぞれ供給される。この装置においてはパージ工程にパージ空気ブロワーＣは使用していないので不要となっている。
このステップにおいては吸着塔が３塔からなるＰＳＡであり、
ａ．第１の塔が吸着操作をしている間にその前段のステップですでに吸着工程を終了した第３の塔の出口端と脱着工程を終えた第２の塔の出口端を連結してパージ工程を行う工程と、
ｂ．引き続き第１の吸着塔が吸着工程にあり、パージ工程を終えた第２の塔入り口端から第３の塔からの均圧用ガスを導入（同時に第３の塔から塔内の残留ガスを向流に放出してもよい。）すると共に昇圧空気圧縮機Ｂから昇圧用の空気を導入する均圧を行う工程と、さらに
ｃ．引き続き第１の塔が吸着を行い、第２の塔は引き続き第２の塔出口から昇圧空気圧縮機Ｂからの昇圧用空気を導入し、第３の塔は塔入口端より塔内のガスを完全に脱着する工程
からなり、続いてステップ４においてａ．工程の第１吸着塔は第２吸着塔と読み替えて次々同様な操作をする工程を順次第２吸着塔、第３吸着塔に繰り返し行うことにより低濃度酸素を製造することからなる。
【００１４】
さらに図４のプロセスにおいては、吸着工程及びパージ工程の両者の工程において使用するガスは空気であり、均圧工程及び昇圧用のガスとしては製品酸素ガスを使用する。吸着工程の空気は原料空気圧縮機Ａからの空気を、パージ工程の空気はパージ空気ブロワーＣからの空気を使用する。
このステップにおいては吸着塔が３塔からなるＰＳＡであり、
ａ．第１の塔が吸着操作をしている間にその前段のステップですでに吸着工程を終了した第３の塔の出口端とパージ工程を終えた第２の塔の出口端を連結して均圧操作を行うと同時にパージを終えた第２の塔の出口端から製品酸素ガスを導入する工程、
ｂ．引き続き第１の吸着塔が吸着工程にあり、均圧工程を終えた第３の塔入り口端から塔内に残留するガスを放出して減圧を行い（同時に第２の塔の入口端にさらに昇圧ガスを供給してもよい。）、また第２塔の出口端から第１塔からの製品酸素ガスを導入して昇圧を続け、さらに
ｃ．引き続き第１の塔が吸着を行い、第２の塔は引き続き第１の塔からの製品ガスの一部を導入して吸着圧に到達するように昇圧を行い、第３の塔は塔出口端より塔内に残留するガスを放出する脱着工程さらに
ｄ．引き続き第１の塔の吸着塔は吸着工程にあり、第２の塔は同じく第１の塔からの製品ガスの一部を導入して吸着圧に到達するように昇圧を行い、第３の塔は塔入口から空気を導入してパージ工程を行う工程
からなり、続いてステップ５においてａ．工程の第１吸着塔は第２吸着塔と読み替え、第２吸着塔を第３吸着塔と読み替え、さらに第３吸着塔を第１吸着塔と読み替えることによる次々同様な操作をする工程を順次第２吸着塔、第３吸着塔に繰り返し行うことにより低濃度酸素を製造することからなる。
【００１５】
なお各図面において減圧ポンプＤが記載されているがこれは設置しなくとも問題はないが、脱着工程の際に残留ガスの追い出しに併用することは製造効率が向上するので設置することもできる。
以上の説明からも明らかなように本発明においては、パージ用ガス及び昇圧用のガスのいずれかに空気を使用するものであり、好ましくはその双方に空気を使用するものである。その際昇圧用の空気は吸着塔に対し向流に供給することが好ましく、またパージ用の空気は並流に供給することが好ましい。特に好ましくはパージ工程においては並流に、昇圧工程においては向流に空気を供給する組み合わせあるいはその逆にパージ工程においては向流に、昇圧工程においては並流の組み合わせにある空気の供給方法が好ましい。
【００１６】
３塔式ＰＳＡに限らないが、このような空気の供給法を取るに際しては、吸着塔の入口端と出口端の双方に活性アルミナ、シリカゲルなどの吸着剤を充填した水分吸着層を設けた吸着塔とすることによりＰＳＡ用の吸着剤の吸湿を防ぐことが可能である。また水分吸着層を設けるため、吸着塔の内容積の減少を防ぎたい時には、水分吸着剤を充填した２塔以上の水分吸着装置を設け、昇圧空気圧縮機Ｂ及び／またはパージ空気ブロワーＣからの空気をあらかじめ脱湿処理して吸着塔に送入するようにしても構わない。できれば吸着塔の入口端及び出口端に水分吸着層を設けた吸着塔を使用することが好ましい。
【００１７】
本発明のＰＳＡは、３塔のうちいずれかのものが常時吸着工程にあって、吸着塔へ空気を連続的に供給する必要があり、またステップの組み合わせによっては常時いずれかの吸着塔が昇圧用空気を必要とする均圧工程あるいは昇圧工程もにある場合があって昇圧空気圧縮機Ｂは常時運転が必要となるプロセスもあり、一方パージ工程においてはさほど高い圧力を必要としないのでこの工程においては圧縮機に代えてエネルギー効率の高いブロワーを使用することも可能なプロセスとすることもできる。この結果本発明のＰＳＡ装置においては原料空気圧縮機Ａとともに昇圧空気圧縮機Ｂ及び／またはパージ空気ブロワーＣを併設することによって効率の高い酸素製造ができることになる。
【００１８】
またこのように工程を組むことにより、製品ガスの圧力は従来のＰＳＡが減圧〜最高３ｋｇ／ｃｍ2 位であるのに対し、容易に５ｋｇ／ｃｍ2 程度を確保できる利点もある。このような製品ガスの高い圧力は高圧操業をしている熔解炉や産業廃棄物のための特殊な焼却炉の助燃用ガスとして特に有利である。
本発明のＰＳＡは大型のものだけでなく通常ＰＳＡが使用されている小型の装置、あるいは中型の装置でも可能であるが、特に大規模のものの対応策としては大型のＰＳＡユニットを複数併設して同一のサイクルで位相を代えて操業することが好ましい。これは比較的低濃度の酸素富化空気を直接ＰＳＡで製造する場合、高濃度の酸素を空気と混合希釈して低濃度の酸素富化空気を供給する場合に比べ酸素濃度の変動幅は大きくなるのが普通である。このため需要先が許容できる変動幅になる程度の大きさのクッションタンクを置くことが望ましいが、複数のユニットを位相を代えて操業する時は、それぞれのＰＳＡステップの酸素濃度変化を干渉により打ち消すことになり酸素濃度の均一化にとっても有利であり、また間欠運転を必要とされるパージ空気ブロワーを複数のユニットで共有することが可能となり、イニシャルコストの節減にもなり有利である。
【００１９】
【作用】
ＰＳＡによる酸素製造の原理は、通常モレキュラーシーブゼオライトのような窒素吸着剤を充填した１基以上の吸着塔に比較的高い圧力で空気を導入して窒素を吸着させ、酸素富化ガスを製品として取り出す。そして吸着した窒素が吸着塔からブレークスルーする前に空気の導入を停止し、次にその塔を比較的低い圧力へ移すことによってモレキュラーシーブゼオライトに吸着されている窒素を脱着させ塔を再生させることにある。構成する吸着塔の数、再生圧力を大気圧または真空圧で行うか、圧力回収をどのように行うかで様々なシステムが組み立てられている。
ところでこれらのＰＳＡシステムは、基本的には酸素収率（％）、吸着剤要求量（＝ＢＳＦ；ｋｇ吸着剤／ｔｏｎ酸素発生量／日）及び電力原単位（Ｋｗｈ／Ｎｍ3 酸素）の３つの指針で評価される。
【００２０】
本発明は、２３〜５０ｖｏｌ％のような低濃度の酸素富化空気を効率的に製造するためのプロセス、その実施のための装置に関するものである。
従来のＰＳＡが、製品ガス中の酸素濃度の高いガスを目的として、パージ工程、昇圧工程に使用するガスを製品である高純度の酸素ガスを使用して製品ガスの酸素濃度を維持しようとしているのに対し、本発明では製品ガス中の酸素濃度を使用に適する低濃度の酸素富化空気を目的としているので、そのような効率の低下するステップを放擲し、パージ工程または昇圧工程のいずれかあるいはその双方のステップに使用するガスを空気にすることにより効率の向上が可能となり、このため単位エネルギーあたりの酸素製造量は大幅に向上できた。
さらに吸着塔の塔内洗浄のためのパージ用のガスを、空気に代えたこと及び操業を常圧に近い低圧での操業が可能なためパージ空気ブロワーの使用することによりエネルギー効率の向上を図っている。従来のＰＳＡでは製品ガスを使用しているため、ＰＳＡの操業圧力を維持する必要があるので原料空気圧縮機でなければならなかったのに対し、低圧のブロワーでこれを代えることによりエネルギーの効率の向上が達成できた。
【００２１】
吸着工程（製品ガスを製造する工程）は、原料空気圧縮機から連続的に空気を供給することにより行われるので、従来のものより操業圧力は高く維持することは可能であり、高圧力の製品ガスを製造できる。
特に大型の低濃度の酸素富化空気を必要とするような場合には複数のＰＳＡユニットを並列的に、同一のサイクルで位相を代えて操業するときは装置の一部の共有を可能となるだけでなく、操業切替などのための酸素濃度変動を抑え均一化にさらに有利に使用できるメリットがある。
【００２２】
【実施例】
［実施例１］
図１に示す装置で内径６００ｍｍ、直胴部の高さ２４００ｍｍの鋼鉄製の吸着塔第１〜第３の各々に対して、塔入口端側に直径２〜５ｍｍのビーズ状活性アルミナを高さ４００ｍｍに充填し、その上部に直径２〜３ｍｍ、嵩密度７００ｇ／ＬのＮａ−１３Ｘゼオライトを高さ２０００ｍｍに充填した。原料空気圧縮機Ａ及び昇圧空気圧縮機Ｂは２段レシプロ型空気圧縮機、パージ空気ブロワーＣは吐出圧力０．１ｋｇ／ｃｍ2 Ｇのターボ型空気送風機を使用した。
図１に示すサイクルステップにおいて、酸素富化空気の酸素濃度３０％、吸着圧力は５ｋｇ／ｃｍ2 Ｇ、脱着圧力は大気圧としてサイクルタイム１８０秒で運転した。この結果、下記のエネルギー効率が得られた。
酸素収率 ７１．２％
ＢＳＦ ２８７ｋｇ吸着剤／ｔｏｎ酸素／日
電力原単位 ０．３９６Ｋｗｈ／Ｎｍ3 酸素
【００２３】
［実施例２］
図４に示す装置で、実施例１と同じ吸着剤を同量使用し、図４に示すサイクルステップを、酸素富化空気の酸素濃度３０％、吸着圧力は５ｋｇ／ｃｍ2 Ｇ、脱着圧力は大気圧としてサイクルタイム１８０秒で運転した。この結果、下記のエネルギー効率が得られた。
酸素収率 ７０．４％
ＢＳＦ ３０４ｋｇ吸着剤／ｔｏｎ酸素／日
電力原単位 ０．４４８Ｋｗｈ／Ｎｍ3 酸素
【００２４】
［実施例３］
図３に示す装置を使用した。ただし、原料空気圧縮機Ａ及び昇圧空気圧縮機Ｂは吐出圧力０．１ｋｇ／ｃｍ2 Ｇのターボ型空気送風機、真空ポンプＤは２段水封ルーツブロワーを使用し、パージ空気ブロワーＣは使用しなかった。吸着剤は嵩密度６６０ｇ／ＬのＣａ−１３Ｘゼオライトを使用した。
図３に示すサイクルステップを、酸素富化空気の酸素濃度３０％、吸着圧力は０．１ｋｇ／ｃｍ2 Ｇとし脱着圧力は２６０ｔｏｒｒとして、サイクルタイム１５０秒で運転した。そしてＰＳＡで製造したほぼ大気圧の酸素富化空気を２段レシプロ型酸素圧縮機（記載していない。）によって４．５ｋｇ／ｃｍ2 Ｇまで圧縮した。この結果、下記のエネルギー効率が得られた。
酸素収率 ７８．５％
ＢＳＦ ５６１ｋｇ吸着剤／ｔｏｎ酸素／日
電力原単位 ０．３７５Ｋｗｈ／Ｎｍ3 酸素
【００２５】
［比較例１］
図５に示す装置で、実施例１と同じ吸着剤を同量使用し、図５に示すサイクルステップを、酸素富化空気の酸素濃度３０％、吸着圧力は５ｋｇ／ｃｍ2 Ｇ、脱着圧力は大気圧としてサイクルタイム１８０秒で運転した。図５は図４に対してパージガスを製品ガスで向流に行う点が異なっている。この結果、下記のエネルギー効率が得られた。
酸素収率 ６６．８％
ＢＳＦ ３３１ｋｇ吸着剤／ｔｏｎ酸素／日
電力原単位 ０．５３８Ｋｗｈ／Ｎｍ3 酸素
【００２６】
［比較例２］
比較例１と同じ装置及び吸着剤を使用し、図５に示すサイクルステップにおいて、酸素富化空気の酸素濃度９０％、吸着圧力は５ｋｇ／ｃｍ2 Ｇ、脱着圧力は大気圧としてサイクルタイム１８０秒で運転した。この結果、下記のエネルギー効率が得られた。
酸素収率 ４２．７％
ＢＳＦ ８６４ｋｇ吸着剤／ｔｏｎ酸素／日
電力原単位 ０．８３１Ｋｗｈ／Ｎｍ3 酸素
この結果に対して、得られた酸素濃度９０％の酸素富化空気を３０％まで空気で希釈すると下記のエネルギー効率が得られた。
総合酸素収率 ６５．６％
総合ＢＳＦ ３３８ｋｇ吸着剤／ｔｏｎ酸素／日
また希釈空気の圧力を実施例１と同じ性能の２段レシプロ型空気圧縮機によって４．５ｋｇ／ｃｍ2 Ｇまで昇圧した時の総合電力原単位は下の通りであった。
総合電力原単位 ０．５２８Ｋｗｈ／Ｎｍ3 酸素
【００２７】
［比較例３］
実施例３と同じ装置（ただし昇圧空機圧縮機Ｂは使用しなかった。）及び吸着剤を使用した。図６に示すサイクルステップにおいて、酸素富化空気の酸素濃度９０％、サイクルタイム１５０秒で運転した。本比較例は製品酸素で昇圧することが実施例３とは異なっている。この結果、下記のエネルギー効率が得られた。
酸素収率 ５２．０％
ＢＳＦ １６４６ｋｇ吸着剤／ｔｏｎ酸素／日
電力原単位 ０．３９６Ｋｗｈ／Ｎｍ3 酸素
この結果に対して、得られた酸素濃度９０％の酸素富化空気を３０％まで空気で希釈すると下記のエネルギー効率が得られた。
総合酸素収率 ７３．５％
総合ＢＳＦ ６４４ｋｇ吸着剤／ｔｏｎ酸素／日
また９０％酸素濃度の酸素富化空気及び希釈空気の圧力を実施例３と同じ性能の２段レシプロ型空気圧縮機によって４．５ｋｇ／ｃｍ2 Ｇまで昇圧した時の総合電力原単位は下の通りであった。
総合電力原単位 ０．３８９Ｋｗｈ／Ｎｍ3 酸素
【００２８】
以上の結果からも明らかなように、比較例１と比較例２に示すように同じサイクルステップで運転する場合、ＰＳＡによって９０％酸素濃度の酸素ガスを製造して、空気で３０％酸素濃度の酸素富化空気まで希釈するのと、ＰＳＡで直接３０％酸素濃度の酸素富化空気を製造するのとでは、酸素収率、ＢＳＦ及び電力原単位においてほとんど差がないが、実施例１と比較例１及び比較例２、さらに実施例３と比較例３とを比較すれば明らかなように、パージガス及び／または昇圧ガスを空気とした場合においては、酸素収率、ＢＳＦ及び電力原単位について格段の優位性が認められる。
【００２９】
【発明の効果】
本発明は、低濃度の酸素富化空気の製造を目的として、脱着工程の終了した吸着塔の塔内洗浄のためのパージ用ガス及び／または再生した塔の昇圧用のガスとして空気を用いるＰＳＡであり、このため、
▲１▼ 低濃度酸素製造のために、エネルギーあたりの生産酸素量が大きい。
▲２▼ パージ空気ブロワーを使用しているのでエネルギー消費が少なくて済む。
▲３▼ 吸着工程（製造工程）の操業圧力を高くできるので、製品ガスの圧力を高くできる。
▲４▼ 複数ユニットを併設するときは、パージ空気ブロワーを兼用させることにより設備費を小さくすることができる。
▲５▼ 複数のユニットを位相を変えて操業することにより、圧力変動を小さくできる。
等多くの利点を有するプロセスであり、必要な濃度の酸素を安価に得ることができる。
このため、例えば鉄鋼精練、非鉄金属精練、窯業、化学、発酵、ゴミ焼却、廃水処理など、低純度酸素を必要とする分野に安価な酸素を供給することが可能となった。
【図面の簡単な説明】
【図１】本発明を実施するためのＰＳＡ装置の一例のフローチャート及び該装置のための操作の一つのステップを示す。
【図２】本発明を実施するためのＰＳＡ装置の一例のフローチャート及び該装置のための操作の一つのステップを示す。
【図３】本発明を実施するためのＰＳＡ装置の一例のフローチャート及び該装置のための操作の一つのステップを示す。
【図４】本発明を実施するためのＰＳＡ装置の一例のフローチャート及び該装置のための操作の一つのステップを示す。
【図５】従来のＰＳＡ装置の一例を示すフローチャート及びその操作ための一つのステップを示す。
【図６】従来のＰＳＡ装置の一例を示すフローチャート及びその操作ための一つのステップを示す。
【符号の説明】
Ａ 原料空気圧縮機
Ｂ 昇圧空気圧縮機
Ｃ パージ空気ブロワー
Ｄ 減圧ポンプ
１Ａ，２Ａ，３Ａ，４Ａ，８Ａなど 自動切換バルブ
５，１０，１４，１６，１８など バルブ[0001]
[Industrial application fields]
The present invention relates to an operation method and an apparatus therefor for efficiently producing low-concentration oxygen-enriched air from air by pressure fluctuation adsorption (PSA) using an adsorbent such as molecular sieve.
[0002]
[Prior art]
Conventionally, the most economical method for producing oxygen-enriched air in industrial equipment has been said to be the method of diluting and using oxygen produced by an on-site low-temperature liquefied air separation device. This method is not only limited to very large plants, but the overall cost is relatively high and is used to increase the efficiency of the combustion furnace using oxygen-enriched air and reduce air pollution. However, it is expensive in terms of cost and has a great influence on adoption.
[0003]
On the other hand, the PSA method was developed in the 1970s, and it became possible to produce oxygen easily even in a relatively small apparatus, and oxygen-enriched air could be supplied by a small oxygen generator, and oxygen-enriched. The field of use of chemical air has been greatly expanded. In particular, recently, the oxygen production method using PSA has been remarkably developed technically, and it has become possible to enter a large-scale field that has been referred to as a low-temperature liquefaction separation apparatus. In particular, the low-temperature liquefied oxygen separator is being replaced in view of its low construction cost and running cost, extremely short rise time, and ease of maintenance. Observing the history of the development of these PSA, it was limited to those aimed at improving the energy efficiency in the generation of high-purity oxygen, and mainly the methods aimed at higher-purity oxygen concentrations. When the produced oxygen-enriched air (usually oxygen concentration of about 90 to 93%) is more pure than necessary, depending on the field of use, the produced oxygen-enriched air is diluted with air. There was even a case of using.
[0004]
Another method for producing oxygen-enriched air is to use a permeable membrane. This membrane utilization system is simple and can produce oxygen at a low concentration of 30-40%. The device itself is simple and seems to be an excellent method for a relatively small demand field. Although there are several such methods, the air liquefaction separation method has mainly been adopted in large-scale oxygen demand fields.
Looking at the current usage situation, for example, in a large-scale combustion furnace, the use of oxygen-enriched air for combustion increases the combustion temperature, increases the combustion efficiency, or contributes to the reduction of air pollution. There are many industries. For this purpose, in general, 99.5% or more of liquid oxygen is transported to an on-site storage tank and mixed with air to adjust the combustion temperature and extend the life of the combustion furnace wall refractory. A method of producing a low-concentration oxygen-enriched air, or additionally blowing high-purity oxygen into a combustion furnace that is burning with air is used. In particular, in the case of a large-sized device with a large demand for oxygen, it has been carried out to produce high-purity oxygen by installing a low-temperature air separation device on site instead of transporting liquid air in order to reduce costs. .
[0005]
However, in terms of energy efficiency, it is meaningless to once produce high-purity oxygen and dilute it with air before use, and oxygen-enriched air with the desired oxygen concentration can be produced from the beginning. It goes without saying that it is desirable. For this purpose, in the case of oxygen-enriched air having a low oxygen concentration of less than 50 vol%, the permeable membrane method is suitable for the oxygen concentration of the oxygen-enriched air produced. The equipment cost is extremely high, and it cannot be said that it is an advantageous method because there is anxiety about the life of the permeable membrane. In the air liquefaction separation method, it is meaningless to produce low concentration oxygen-enriched air, such as less than 50 vol%, because it is performed through the production of liquid air. Improving energy efficiency cannot be expected even by direct manufacturing. Further, in the PSA method, there has not yet been developed an energy-efficient operation process for low-concentration oxygen-enriched air or an apparatus therefor.
[0006]
[Problems to be solved by the invention]
The present invention is an operation of a PSA system capable of producing an oxygen-enriched air having a low concentration, particularly an oxygen-enriched air having an oxygen concentration of 50 vol% or less, which can be used even in a large apparatus, with extremely high energy efficiency per production oxygen. The object is to develop a method and a manufacturing apparatus therefor.
[0007]
[Means for Solving the Problems]
The present invention
[1] In a pressure fluctuation adsorption method (PSA) for producing low-concentration oxygen-enriched air consisting of three adsorption towers, purge gas and / or pressure increase for cleaning the inside of the adsorption tower after completion of the desorption process PSA for low-concentration oxygen that uses air as the gas for operation,
[2] A PSA for producing low-concentration oxygen-enriched air having three adsorption towers, wherein PSA for low-concentration oxygen uses air as the gas used in the pressurization process by counterflow of the adsorption tower after the purge process. ,
[3] In a PSA for producing low-concentration oxygen-enriched air having three adsorption towers, air is used as a gas used in a co-current purge process for washing the adsorption tower after completion of the adsorption process. PSA for low concentration oxygen,
[4] In a PSA for producing low-concentration oxygen-enriched air having three adsorption towers,
a. While the first tower is performing the adsorption operation, the outlet end of the third tower, which has already completed the adsorption process in the previous step, and the inlet end of the second tower, which has completed the purge process, are connected and leveled. A step of introducing pressurized air from the outlet end of the second tower which has been purged at the same time as the pressure operation;
b. Subsequently, the first adsorption tower is in the adsorption process, the gas remaining in the tower is discharged from the inlet end of the third tower after the pressure equalization process, and the pressure is reduced, and air is introduced from the outlet end of the second tower. And continue boosting,
c. The first tower continues to adsorb, the second tower continues to increase pressure to reach the adsorption pressure, and the third tower introduces air from the tower inlet end toward the tower outlet end. Purging process for washing in the parallel flow direction
A method for producing low-concentration oxygen, comprising transferring the steps comprising:
[5] In a PSA for producing low-concentration oxygen-enriched air having three adsorption towers,
a. While the first tower is performing the adsorption operation, the outlet end of the third tower, which has already completed the adsorption process in the previous step, is connected to the outlet end of the second tower, which has completed the purge process. Introducing pressurized air from the inlet end of the second tower that has been purged at the same time as the pressure operation; b. Subsequently, the first adsorption tower is in the adsorption process, the gas remaining in the tower is discharged from the third tower inlet end after the pressure equalization process, and the pressure is reduced, and air is introduced from the second tower inlet end. And continue boosting,
b. Subsequently, the first tower performs adsorption, the second tower continues to increase pressure so as to reach the adsorption pressure, and the third tower introduces air from the tower outlet end toward the tower inlet end. Purging process for washing in the counterflow direction
A method for producing low-concentration oxygen, comprising transferring the steps comprising:
[6] The method for producing low-concentration oxygen according to the above [1] to [5], wherein the oxygen concentration of the low-concentration oxygen-enriched air is 23 to 50 vol%.
[7] In a PSA apparatus for producing low-concentration oxygen-enriched air having three adsorption towers, a raw material air compressor for the adsorption process, a pressure equalizing process after the purge process, and a pressurized air compressor for the pressure increasing process And a PSA apparatus provided with a purge air blower used in a purge process for cleaning the inside of the tower, and
[8] Manufactures enriched air for low-concentration oxygen that is supplied as counter-flow to the adsorption tower using air as a purge gas and / or a pressure-increasing gas for cleaning the adsorption tower after the adsorption process. In the PSA apparatus, the water adsorbent is charged at the inlet end and the outlet end of each adsorption tower, or two or more water adsorbers filled with the moisture adsorbent are provided separately, and air and / or pressure increase used in the purge process The above object was achieved by developing a low-concentration oxygen PSA device that was piped so that the air used in the process could be processed.
[0008]
The oxygen concentration of the low-concentration oxygen-enriched air produced in the present invention is in principle 23 vol% to 50 vol% oxygen-enriched air, and the basic configuration of the PSA apparatus for that purpose is a PSA apparatus conventionally used. Can be used as is or with a slight modification. Moreover, the absorbent used for oxygen separation can be used as long as it can selectively absorb nitrogen or oxygen, such as a molecular sieve (zeolite) conventionally used.
In the conventional PSA, as shown in the examples of FIGS. 5 and 6, the product gas is used in any of the purge step of the adsorption tower after the desorption step, the pressure equalization step after the completion, and the pressure increase step after pressure equalization. Because of the necessity of maintaining purity, adsorption process gas (product oxygen gas) or high-purity oxygen gas immediately after the adsorption process is used. For this reason, the oxygen concentration in the adsorption tower can be kept high, so that the product oxygen gas concentration can be kept high, but the amount of produced gas per cycle becomes small and energy efficiency has to be lowered.
[0009]
The first invention of the present invention is a PSA having three adsorption towers, and unlike conventional PSA, low concentration oxygen-enriched air, particularly low concentration oxygen-enriched air such as 50 vol% or less. A purging gas and / or a purging process for cleaning an adsorption tower after a desorption process in which a conventional PSA uses a product oxygen gas to increase energy efficiency per manufactured oxygen. The air is used as a gas for pressurization of the later adsorption tower.
In the second invention of the present invention, the adsorption tower is also a PSA of three towers, and air is used as a gas used in the pressurization process of the adsorption tower after the purge process is completed. On the other hand, it supplies from a countercurrent direction. As a result, the moisture in the air is adsorbed by the moisture adsorbent provided at the outlet end of the adsorption tower or the moisture adsorbing device provided on the outlet side, and water absorption by the oxygen adsorbent can be prevented.
The third invention of the present invention uses air as a gas used in the purge process for cleaning the adsorption tower after completion of the adsorption process in a PSA producing low concentration oxygen-enriched air consisting of three adsorption towers. This air is supplied to the adsorption tower from the parallel flow direction.
[0010]
The PSA apparatus of the present invention is provided with a raw material air compressor A, a pressurized air compressor B, and a purge air blower C in parallel for supplying air, and these are efficiently operated to maintain high energy efficiency. In particular, the improvement in energy efficiency by providing the purge air blower C is remarkable.
In addition, in the conventional PSA, the adsorption tower generally hardly supplies air to the adsorption tower from the countercurrent direction. However, in the step of the present invention, such a method of supplying air is possible. Is installed in the inlet end and outlet end of the adsorption tower, or a moisture adsorption device filled with a moisture adsorbent is provided separately to make it possible to process purge air and pressurization air.
Further, in the present invention, a plurality of PSA units are provided in a case where a large amount of low-concentration oxygen-enriched air such as a power generation boiler, a large waste incineration plant, and a melting furnace is required. In the same cycle, the operation cost is increased by adopting a method of jointly using a plurality of purge air blowers, for example, one purge air blower C in 3 units, by operating with different phases. It becomes possible to reduce.
[0011]
Hereinafter, the present invention will be described in detail with reference to the drawings. The steps shown in this figure are merely examples for carrying out the present invention, and the present invention is not limited to these steps.
In the process of FIG. 1, the air used in the adsorption process is from the raw material air compressor A, and the gas used in any of the pressure equalizing process, purge process, and pressure increasing process is air, and the air in the pressure equalizing process is pressurized air. Supplied from the compressor B, the air in the purge process is supplied from the purge air blower C, and the air in the pressurization process is supplied from the pressurization air compressor B.
In this step, the adsorption tower is a PSA consisting of three towers,
a. While the first tower is performing the adsorption operation, the outlet end of the third tower, which has already completed the adsorption process in the previous step, and the inlet end of the second tower, which has completed the purge process, are connected and leveled. A step of introducing pressurized air from the outlet end of the second tower which has been purged at the same time as performing the pressure operation;
b. Subsequently, the first adsorption tower is in the adsorption process, the gas remaining in the tower is discharged from the inlet end of the third tower after the pressure equalization process, and the pressure is reduced, and air is introduced from the outlet end of the second tower. And continue boosting,
c. The first tower continues to adsorb, the second tower continues to increase pressure to reach the adsorption pressure, and the third tower introduces air from the tower inlet end toward the tower outlet end. Washing process in the parallel flow direction
And in step 4 a. In the process, the first adsorption tower is read as the second adsorption tower, the second adsorption tower is read as the third adsorption tower, and the third adsorption tower is read as the first adsorption tower and the same operation steps are sequentially performed. It consists of producing low concentration oxygen by repeating to 2 adsorption towers and the 3rd adsorption tower.
[0012]
In the process of FIG. 2, the air used in the adsorption process is from the raw material air compressor A, and the gas used in any of the pressure equalization process, the purge process, and the pressure increase process is air, and the air in the pressure equalization process is the pressurized air. Supplied from the compressor B, the air in the purge process is supplied from the purge air blower C, and the air in the pressurization process is supplied from the pressurization air compressor B.
In this step, the adsorption tower is a PSA consisting of three towers,
a. While the first tower is performing the adsorption operation, the outlet end of the third tower, which has already completed the adsorption process in the previous step, is connected to the outlet end of the second tower, which has completed the purge process. A step of introducing pressurized air from the inlet end of the second tower which has been purged at the same time as the pressure operation;
b. Subsequently, the first adsorption tower is in the adsorption process, the gas remaining in the tower is discharged from the third tower inlet end after the pressure equalization process, and the pressure is reduced, and air is introduced from the second tower inlet end. And continue boosting,
c. Subsequently, the first tower performs adsorption, the second tower continues to increase pressure so as to reach the adsorption pressure, and the third tower introduces air from the tower outlet end toward the tower inlet end. Purging process for washing in the counterflow direction
And in step 4 a. The first adsorption tower of the process consists of producing low-concentration oxygen by repeatedly performing the same operation one after another in the second adsorption tower and the third adsorption tower.
[0013]
In the process of FIG. 3, the air in the adsorption process is from the raw material air compressor A, the gas used in both the pressure equalization process and the pressure increase process is air, and the gas in the purge process is the decompression after completion of the adsorption process. Gas is used. Air in the pressure equalizing process is supplied from the pressurized air compressor B, and air in the pressure increasing process is supplied from the pressurized air compressor B. In this apparatus, the purge air blower C is not used in the purge process, and is therefore unnecessary.
In this step, the adsorption tower is a PSA consisting of three towers,
a. Purging by connecting the outlet end of the third tower that has already completed the adsorption process in the previous step and the outlet end of the second tower that has completed the desorption process while the first tower is performing the adsorption operation Performing the process;
b. Subsequently, the first adsorption tower is in the adsorption process, and the pressure equalizing gas from the third tower is introduced from the inlet end of the second tower after the purge process is completed (at the same time, the residual gas in the tower is counterflowed from the third tower. And a pressure equalizing process for introducing pressure-increasing air from the pressure-increasing air compressor B, and
c. The first tower continues to adsorb, the second tower continues to introduce pressurized air from the pressurized air compressor B from the second tower outlet, and the third tower draws the gas in the tower from the tower inlet end. Complete desorption process
And in step 4 a. The first adsorption tower of the process consists of producing low-concentration oxygen by repeatedly performing the same operation one after another in the second adsorption tower and the third adsorption tower.
[0014]
Further, in the process of FIG. 4, the gas used in both the adsorption process and the purge process is air, and the product oxygen gas is used as the pressure equalizing process and the pressure increasing gas. Air from the raw material air compressor A is used as the air in the adsorption process, and air from the purge air blower C is used as the air in the purge process.
In this step, the adsorption tower is a PSA consisting of three towers,
a. While the first tower is performing the adsorption operation, the outlet end of the third tower, which has already completed the adsorption process in the previous step, is connected to the outlet end of the second tower, which has completed the purge process. A step of introducing product oxygen gas from the outlet end of the second tower which has been purged at the same time as the pressure operation;
b. Subsequently, the first adsorption tower is in the adsorption process, and the gas remaining in the tower is discharged from the third tower inlet end after the pressure equalization process, and the pressure is reduced (at the same time, the pressure is further increased at the inlet end of the second tower). Gas may be supplied.) Further, the product oxygen gas from the first tower is introduced from the outlet end of the second tower and the pressure is continuously increased.
c. The first tower continues to adsorb, the second tower continues to introduce part of the product gas from the first tower and pressurizes to reach the adsorption pressure, and the third tower is at the tower outlet end. More desorption process for releasing the gas remaining in the tower
d. Subsequently, the adsorption tower of the first tower is in the adsorption process, and the second tower is also pressurized to reach the adsorption pressure by introducing a part of the product gas from the first tower, and the third tower. Is the process of purging by introducing air from the tower inlet
And in step 5 a. In the process, the first adsorption tower is read as the second adsorption tower, the second adsorption tower is read as the third adsorption tower, and the third adsorption tower is read as the first adsorption tower and the same operation steps are sequentially performed. It consists of producing low concentration oxygen by repeating to 2 adsorption towers and the 3rd adsorption tower.
[0015]
Although the decompression pump D is described in each drawing, there is no problem even if it is not installed. However, it is also possible to install the decompression pump D in combination with the removal of residual gas during the desorption process because the manufacturing efficiency is improved.
As is clear from the above description, in the present invention, air is used for either the purge gas or the pressure-increasing gas, and preferably air is used for both. At that time, it is preferable to supply the pressure-increasing air countercurrently to the adsorption tower, and it is preferable to supply the purge air in parallel flow. Particularly preferably, there is a method of supplying air in a combination of supplying the air in the purge process in a cocurrent flow, in the pressurization process in a countercurrent flow, or vice versa in the purge process in a countercurrent flow, and in the pressure increase process in a cocurrent flow combination. preferable.
[0016]
Although not limited to the three-column PSA, when such an air supply method is adopted, an adsorption layer provided with a moisture adsorption layer filled with an adsorbent such as activated alumina or silica gel is provided at both the inlet end and the outlet end of the adsorption tower. By using a tower, it is possible to prevent moisture absorption of the PSA adsorbent. In addition, in order to prevent a decrease in the internal volume of the adsorption tower due to the provision of a moisture adsorption layer, two or more moisture adsorption devices filled with a moisture adsorbent are provided, The air may be dehumidified in advance and sent to the adsorption tower. If possible, it is preferable to use an adsorption tower provided with a moisture adsorption layer at the inlet end and the outlet end of the adsorption tower.
[0017]
In the PSA of the present invention, any one of the three towers is always in the adsorption process, and it is necessary to continuously supply air to the adsorption tower. There is a case where there is a pressure equalization process or a pressure increasing process that requires working air, and there is a process in which the pressurized air compressor B needs to be operated at all times. On the other hand, a high pressure is not required in the purge process. In the present invention, a process that can use a blower with high energy efficiency instead of the compressor can be used. As a result, in the PSA apparatus according to the present invention, by providing the pressurized air compressor B and / or the purge air blower C together with the raw material air compressor A, oxygen can be produced with high efficiency.
[0018]
In addition, by assembling the process in this way, the pressure of the product gas is reduced from the conventional PSA to 3 kg / cm 2 5kg / cm 2 There is also an advantage that the degree can be secured. Such a high pressure of the product gas is particularly advantageous as an auxiliary combustion gas for melting furnaces operating at high pressure and special incinerators for industrial waste.
The PSA of the present invention is not limited to a large-sized one but can be a small-sized device or a medium-sized device in which a normal PSA is used. It is preferable to operate by changing the phase in the same cycle. This is because when oxygen-enriched air with a relatively low concentration is directly produced by PSA, the fluctuation range of oxygen concentration is larger than when oxygen-enriched air with low concentration is supplied by mixing and diluting high-concentration oxygen with air. It is normal to become. For this reason, it is desirable to place a cushion tank that is large enough to provide an acceptable fluctuation range for the customer. However, when operating multiple units with different phases, the change in oxygen concentration at each PSA step is canceled by interference. In other words, it is advantageous for uniforming the oxygen concentration, and a purge air blower requiring intermittent operation can be shared by a plurality of units, which is advantageous in terms of reducing initial costs.
[0019]
[Action]
The principle of oxygen production by PSA is that nitrogen is adsorbed by introducing air at a relatively high pressure into one or more adsorption towers usually filled with a nitrogen adsorbent such as molecular sieve zeolite, and oxygen-enriched gas is used as a product. Take out. And before the adsorbed nitrogen breaks through the adsorption tower, stop the introduction of air, and then move the tower to a relatively low pressure to desorb the nitrogen adsorbed on the molecular sieve zeolite and regenerate the tower. It is in. Various systems are assembled depending on the number of adsorbing towers to be constructed, the regeneration pressure is atmospheric pressure or vacuum pressure, and how pressure recovery is performed.
By the way, these PSA systems basically have an oxygen yield (%), an adsorbent requirement (= BSF; kg adsorbent / ton oxygen generation amount / day), and a power unit (Kwh / Nm). Three (Oxygen).
[0020]
The present invention relates to a process for efficiently producing low concentration oxygen-enriched air, such as 23 to 50 vol%, and an apparatus for its implementation.
Conventional PSA is trying to maintain the oxygen concentration of product gas by using high purity oxygen gas, which is the product used for purging process and boosting process, for the purpose of gas with high oxygen concentration in product gas On the other hand, the present invention aims at low-concentration oxygen-enriched air suitable for use with the oxygen concentration in the product gas. In addition, the efficiency can be improved by using air as the gas used for both of these steps, so that the amount of oxygen produced per unit energy can be greatly improved.
Furthermore, the purge gas for cleaning the adsorption tower is replaced with air, and the operation can be performed at a low pressure close to normal pressure, so the use of a purge air blower improves energy efficiency. ing. Since conventional PSA uses product gas, it was necessary to maintain the operating pressure of PSA, so it had to be a raw material air compressor. On the other hand, by replacing this with a low-pressure blower, energy efficiency Improvement was achieved.
[0021]
Since the adsorption process (process for producing product gas) is performed by continuously supplying air from the raw material air compressor, it is possible to keep the operating pressure higher than the conventional one, and the high pressure product Can produce gas.
Particularly when large, low-concentration oxygen-enriched air is required, when a plurality of PSA units are operated in parallel and with different phases in the same cycle, a part of the apparatus can be shared. In addition, there is a merit that it can be used more advantageously for uniformization by suppressing fluctuations in oxygen concentration due to operation switching.
[0022]
【Example】
[Example 1]
In the apparatus shown in FIG. 1, for each of the first to third steel adsorption towers having an inner diameter of 600 mm and a straight body height of 2400 mm, a bead-like activated alumina having a diameter of 2 to 5 mm is provided at the tower inlet end side. The upper portion was filled with Na-13X zeolite having a diameter of 2 to 3 mm and a bulk density of 700 g / L to a height of 2000 mm. The raw air compressor A and the pressurized air compressor B are a two-stage reciprocating type air compressor, and the purge air blower C is a discharge pressure of 0.1 kg / cm. 2 A G turbo-type air blower was used.
In the cycle step shown in FIG. 1, the oxygen concentration of oxygen-enriched air is 30% and the adsorption pressure is 5 kg / cm. 2 G, Desorption pressure was set to atmospheric pressure, and the cycle time was 180 seconds. As a result, the following energy efficiency was obtained.
Oxygen yield 71.2%
BSF 287kg adsorbent / ton oxygen / day
Electric power consumption 0.396Kwh / Nm Three oxygen
[0023]
[Example 2]
In the apparatus shown in FIG. 4, the same amount of the same adsorbent as that of Example 1 was used, and the cycle step shown in FIG. 2 G, Desorption pressure was set to atmospheric pressure, and the cycle time was 180 seconds. As a result, the following energy efficiency was obtained.
Oxygen yield 70.4%
BSF 304kg adsorbent / ton oxygen / day
Electric power consumption 0.448Kwh / Nm Three oxygen
[0024]
[Example 3]
The apparatus shown in FIG. 3 was used. However, the raw air compressor A and the pressurized air compressor B have a discharge pressure of 0.1 kg / cm. 2 The turbo air blower G and the vacuum pump D used a two-stage water-sealed roots blower, and the purge air blower C was not used. As the adsorbent, Ca-13X zeolite having a bulk density of 660 g / L was used.
The cycle steps shown in FIG. 3 are performed using an oxygen enriched air oxygen concentration of 30% and an adsorption pressure of 0.1 kg / cm. 2 G was operated at a cycle time of 150 seconds with a desorption pressure of 260 torr. Then, oxygen-enriched air produced by PSA at a pressure of approximately atmospheric pressure is 4.5 kg / cm by a two-stage reciprocating oxygen compressor (not shown). 2 Compressed to G. As a result, the following energy efficiency was obtained.
Oxygen yield 78.5%
BSF 561kg adsorbent / ton oxygen / day
Electric power consumption 0.375Kwh / Nm Three oxygen
[0025]
[Comparative Example 1]
In the apparatus shown in FIG. 5, the same amount of the same adsorbent as in Example 1 was used, and the cycle step shown in FIG. 5 was carried out using an oxygen concentration of oxygen-enriched air of 30% and an adsorption pressure of 5 kg / cm. 2 G, Desorption pressure was set to atmospheric pressure, and the cycle time was 180 seconds. FIG. 5 differs from FIG. 4 in that the purge gas is counterflowed with the product gas. As a result, the following energy efficiency was obtained.
Oxygen yield 66.8%
BSF 331kg adsorbent / ton oxygen / day
Electric power consumption 0.538Kwh / Nm Three oxygen
[0026]
[Comparative Example 2]
In the cycle step shown in FIG. 5 using the same apparatus and adsorbent as in Comparative Example 1, the oxygen concentration of oxygen-enriched air is 90%, and the adsorption pressure is 5 kg / cm. 2 G, Desorption pressure was set to atmospheric pressure, and the cycle time was 180 seconds. As a result, the following energy efficiency was obtained.
Oxygen yield 42.7%
BSF 864kg adsorbent / ton oxygen / day
Electric power consumption 0.831Kwh / Nm Three oxygen
In contrast to this result, when the obtained oxygen-enriched air having an oxygen concentration of 90% was diluted with air to 30%, the following energy efficiency was obtained.
Total oxygen yield 65.6%
Total BSF 338kg adsorbent / ton oxygen / day
The dilution air pressure was 4.5 kg / cm by a two-stage reciprocating type air compressor having the same performance as in Example 1. 2 The total power intensity when boosted to G was as follows.
Total power consumption 0.528Kwh / Nm Three oxygen
[0027]
[Comparative Example 3]
The same apparatus as in Example 3 (however, the pressurized air compressor B was not used) and the adsorbent were used. In the cycle step shown in FIG. 6, the operation was performed with an oxygen concentration of oxygen-enriched air of 90% and a cycle time of 150 seconds. This comparative example differs from Example 3 in that the pressure is increased with product oxygen. As a result, the following energy efficiency was obtained.
Oxygen yield 52.0%
BSF 1646kg adsorbent / ton oxygen / day
Electric power consumption 0.396Kwh / Nm Three oxygen
In contrast to this result, when the obtained oxygen-enriched air having an oxygen concentration of 90% was diluted with air to 30%, the following energy efficiency was obtained.
Total oxygen yield 73.5%
Total BSF 644kg adsorbent / ton oxygen / day
Further, the pressure of the oxygen-enriched air having a 90% oxygen concentration and the pressure of the dilution air was 4.5 kg / cm by a two-stage reciprocating type air compressor having the same performance as in Example 3. 2 The total power intensity when boosted to G was as follows.
Total power consumption 0.389Kwh / Nm Three oxygen
[0028]
As is clear from the above results, when operating in the same cycle step as shown in Comparative Example 1 and Comparative Example 2, 90% oxygen concentration oxygen gas is produced by PSA and 30% oxygen concentration is produced by air. There is almost no difference in oxygen yield, BSF, and power intensity in the case of diluting to oxygen-enriched air and directly producing 30% oxygen-concentrated air with PSA, but compared with Example 1. As is clear from the comparison between Example 1 and Comparative Example 2, and Example 3 and Comparative Example 3, when the purge gas and / or the pressurizing gas is air, the oxygen yield, BSF, and electric power consumption are remarkably increased. The superiority of is recognized.
[0029]
【The invention's effect】
The present invention aims at producing low-concentration oxygen-enriched air, and uses PSA that uses air as a purging gas for cleaning the adsorption tower after completion of the desorption process and / or as a pressure-boosting gas for the regenerated tower. And for this,
(1) The amount of oxygen produced per energy is large for producing low concentration oxygen.
(2) Since a purge air blower is used, less energy is consumed.
(3) Since the operation pressure in the adsorption process (manufacturing process) can be increased, the product gas pressure can be increased.
(4) When a plurality of units are installed, the equipment cost can be reduced by using a purge air blower as well.
(5) Pressure fluctuation can be reduced by operating a plurality of units with different phases.
It is a process having many advantages, and a necessary concentration of oxygen can be obtained at a low cost.
For this reason, it has become possible to supply inexpensive oxygen to fields that require low-purity oxygen, such as steel refining, non-ferrous metal refining, ceramics, chemistry, fermentation, waste incineration, and wastewater treatment.
[Brief description of the drawings]
FIG. 1 shows a flowchart of an example of a PSA apparatus for implementing the present invention and one step of operation for the apparatus.
FIG. 2 shows a flowchart of an example of a PSA apparatus for implementing the present invention and one step of operation for the apparatus.
FIG. 3 shows a flowchart of an example of a PSA apparatus for implementing the present invention and one step of operation for the apparatus.
FIG. 4 shows a flowchart of an example of a PSA apparatus for implementing the present invention and one step of operation for the apparatus.
FIG. 5 shows a flowchart showing an example of a conventional PSA apparatus and one step for operating the flowchart.
FIG. 6 shows a flowchart showing an example of a conventional PSA apparatus and one step for operating the same.
[Explanation of symbols]
A Raw material air compressor
B Pressurized air compressor
C purge air blower
D Pressure reducing pump
1A, 2A, 3A, 4A, 8A, etc. Automatic switching valve
5, 10, 14, 16, 18 etc. Valve
Claims (8)
ａ．第１の塔が吸着操作をしている間にその前段のステップですでに吸着工程を終了した第３の塔の出口端とパージ工程を終えた第２の塔の入口端を連結して均圧操作を行うと同時にパージを終えた第２の塔の出口端から昇圧空気を導入する工程と、
ｂ．引き続き第１の吸着塔が吸着工程にあり、均圧工程を終えた第３の塔入り口端から塔内に残留するガスを放出して減圧を行い、また第２塔の出口端から空気を導入して昇圧を続け、さらに
ｃ．引き続き第１の塔が吸着を行い、第２の塔は引き続き吸着圧に到達するように昇圧を行い、第３の塔は塔入口端より塔出口端に向かって空気を導入して塔内を向流方向に洗浄するパージ工程
からなる工程を第２吸着塔、第３吸着塔に移し順次繰り返し行うことからなる低濃度酸素の製造方法。In PSA producing low concentration oxygen-enriched air consisting of three adsorption towers,
a. While the first tower is performing the adsorption operation, the outlet end of the third tower, which has already completed the adsorption process in the previous step, and the inlet end of the second tower, which has completed the purge process, are connected and leveled. A step of introducing pressurized air from the outlet end of the second tower which has been purged at the same time as the pressure operation;
b. Subsequently, the first adsorption tower is in the adsorption process, the gas remaining in the tower is discharged from the inlet end of the third tower after the pressure equalization process, and the pressure is reduced, and air is introduced from the outlet end of the second tower. To continue the pressure increase, and c. The first tower continues to adsorb, the second tower continues to increase pressure to reach the adsorption pressure, and the third tower introduces air from the tower inlet end toward the tower outlet end. A method for producing low-concentration oxygen, comprising transferring a step comprising a purge step for washing in the countercurrent direction to the second adsorption tower and the third adsorption tower and successively repeating the steps.
ａ．第１の塔が吸着操作をしている間にその前段のステップですでに吸着工程を終了した第３の塔の出口端とパージ工程を終えた第２の塔の出口端を連結して均圧操作を行うと同時にパージを終えた第２の塔の入口端から昇圧空気を導入する工程と、
ｂ．引き続き第１の吸着塔が吸着工程にあり、均圧工程を終えた第３の塔入り口端から塔内に残留するガスを放出して減圧を行い、また第２塔の入口端から空気を導入して昇圧を続け、さらに
ｃ．引き続き第１の塔が吸着を行い、第２の塔は引き続き吸着圧に到達するように昇圧を行い、第３の塔は塔出口端より塔入口端に向かって空気を導入して塔内を向流方向に洗浄するパージ工程
からなる工程を第２吸着塔、第３吸着塔に移し順次繰り返し行うことからなる低濃度酸素の製造方法。In PSA producing low concentration oxygen-enriched air consisting of three adsorption towers,
a. While the first tower is performing the adsorption operation, the outlet end of the third tower, which has already completed the adsorption process in the previous step, is connected to the outlet end of the second tower, which has completed the purge process. A step of introducing pressurized air from the inlet end of the second tower which has been purged at the same time as the pressure operation;
b. Subsequently, the first adsorption tower is in the adsorption process, the gas remaining in the tower is discharged from the third tower inlet end after the pressure equalization process, and the pressure is reduced, and air is introduced from the second tower inlet end. To continue the pressure increase, and c. Subsequently, the first tower performs adsorption, the second tower continues to increase pressure so as to reach the adsorption pressure, and the third tower introduces air from the tower outlet end toward the tower inlet end. A method for producing low-concentration oxygen, comprising transferring a step comprising a purge step for washing in the countercurrent direction to the second adsorption tower and the third adsorption tower and successively repeating the steps.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13267995A JP3694343B2 (en) | 1995-05-01 | 1995-05-01 | PSA for low concentration oxygen |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13267995A JP3694343B2 (en) | 1995-05-01 | 1995-05-01 | PSA for low concentration oxygen |
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| JPH08301604A JPH08301604A (en) | 1996-11-19 |
| JP3694343B2 true JP3694343B2 (en) | 2005-09-14 |
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| JP4739662B2 (en) * | 2003-09-09 | 2011-08-03 | 帝人株式会社 | Oxygen concentrator |
| KR101659760B1 (en) * | 2015-04-02 | 2016-09-26 | 주식회사 케이디이엔에스 | Apparatus and method for producing nitrogen or oxygen gas using three towers |
| CN106698357A (en) * | 2016-12-28 | 2017-05-24 | 北京金大万翔环保科技有限公司 | Device and method for preparing oxygen through three-tower low pressure adsorption and vacuum desorption |
| US12508534B2 (en) * | 2020-04-14 | 2025-12-30 | Chengdu Yingchen Technology Co., Ltd | Method for mobile pressure swing adsorption oxygen production device |
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