JP3793256B2 - Oxygen concentrator - Google Patents
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【０００１】
【発明の属する技術分野】
本発明は、大気から酸素濃縮気体を分離して使用するための酸素濃縮装置に関する。更に詳細には圧力変動吸着型酸素濃縮装置に関するものであって、少量の供給ガス量で酸素濃縮気体を使用者に供給できるようにした、改善された運転シーケンスを有する酸素濃縮装置に関する。
【０００２】
【従来技術】
近年、ぜんそく、肺気腫症、慢性気管支炎等の呼吸器系器官の疾患に苦しむ患者が増加する傾向にあり、その治療法として最も効果的なものの１つに酸素吸入療法がある。かかる酸素吸入療法とは、酸素ガスあるいは酸素富化空気を患者に吸入させるものである。その酸素ガスや酸素富化空気の供給源として酸素ガスボンベが従来より用いられていたが、近年、空気中から酸素濃縮気体を分離する酸素濃縮装置が開発され、使用時の便利さや保守管理の容易さから次第に普及するようになってきている。
【０００３】
現在、酸素濃縮装置として酸素選択透過膜を用いた膜式酸素濃縮装置と窒素を優先的に吸着し得る吸着剤を用いた圧力変動吸着型酸素濃縮装置があるが、本発明は圧力変動吸着型酸素濃縮装置について改善を加えようとするものである。
【０００４】
これまでの圧力変動吸着型酸素濃縮装置の主なものとしては、コンプレッサーを用いた圧力変動吸着型酸素濃縮装置がある。かかる装置は通常、窒素を優先的に吸着し得る吸着剤を充填した吸着床にコンプレッサーで加圧した圧縮空気を導入し、加圧状態で窒素を吸着することにより酸素濃縮気体を得る吸着工程と、吸着床内の圧力を減じて吸着床の再生を行う脱着工程を交互に行うことにり酸素濃縮気体を得るものである。この場合に、吸着床からの酸素濃縮気体を一時的に貯留しておくためのサージタンクが使用され、サージタンク内に貯留された酸素濃縮気体を患者に供給するとともに、その一部を吸着床に逆流させて吸着床の再加圧や吸着床再生のためのパージに用いられることが多い。
【０００５】
一般に使用されている圧力変動吸着型酸素濃縮装置の吸着床には、窒素、酸素の２成分系吸着平衡に基づく分離係数が２．０〜３．０程度の値を示すモレキュラーシーブゼオライト５Ａ、あるいは１３Ｘを充填したものが広く用いられている。また近年米国にて特公平５−２５５２７号公報に示されるような分離係数が６．０以上の高い分離性能を示すリチウムイオンを有するゼオライトが開発された。
【０００６】
これらゼオライトは高い窒素吸着量を示す反面、吸着工程と脱着工程の切替えの早い装置においては吸着速度が十分でないという問題点を持つ。ゼオライト吸着剤が吸着平衡に達するまでの時間は、ゼオライトの種類、窒素濃度や圧力によって左右されるが、一般に５〜１００分程度の時間を要する。しかし、医療用などの小型の酸素濃縮装置においては、製品ガス流量を確保するために数十秒位の短時間で吸脱着を繰返す方法を採用しており、実際の装置においては吸着剤の平衡吸着量の４０〜７０％の能力しか発揮していない。従ってかかる酸素濃縮装置においては、吸着剤の窒素吸着速度の支配率が大きくなり、吸着剤の性能を示す単位重量当りの吸着量や選択性が向上した高性能窒素吸着剤が開発されてきている現状においても、酸素濃縮効率の改善には限界がある。
【０００７】
上記の様な問題点を有するため、これまでは該酸素濃縮装置で精製する酸素濃縮気体中の酸素濃度が希望の濃度域に達しない場合、吸着剤充填量を増量して吸着床の吸着容量を増加させたり、または空気供給手段の供給能力を上げる、もしくは流動抵抗を低下させることにより吸着床への単位時間当りの供給空気量を増加させるなど、酸素濃縮装置の機械的な改良を行うことにより製品ガス濃度を確保していた。しかし、かかる方法では装置の大型化、消費電力量、生産コストの上昇といった問題が避けられない。
【０００８】
更に、特開平１−２８８３１３号公報、特開平２−１１５０１６号公報では吸着床中でのガス流速を制御することにより、製品ガス中の酸素濃度を向上させる方法を開示している。即ち、吸着床に導入する原料空気及びパージのために吸着床へ導入する製品ガスを間欠的に導入する、即ちパルス流にすることにより、吸着床内でのガス流速が平滑化され、製品ガス濃度を向上させることを明らかにしている。しかしかかる方法においては時間当たりの製品ガス量が十分に確保出来ないという欠点を有し、特開平２−１１５０１６号公報の実施例２に記載の生産性：23.7L・O2/kg・hrでは、医療用途などの小型酸素濃縮装置においてもその酸素ガス生成量は十分とはいえない。
【０００９】
【発明が解決しようとする課題】
本願発明の課題は、圧力変動吸着型酸素濃縮装置の機械的変更を伴うことなく吸着床内での酸素濃縮効率を改善し製品ガスの酸素濃度を向上させ、それにより供給空気量を減じ、空気供給手段の小型化、装置の消費電力の低減を実現することにある。
【００１０】
【課題を解決するための手段】
本願発明者は、かかる問題点を解決することを目的として鋭意検討した結果、吸着剤を充填した吸着床と該吸着床で濃縮した酸素濃縮気体を貯留しておくためのサージタンク手段を有し、吸着床と該サージタンク手段を自動開閉弁手段を配した導管手段によって連結した圧力変動吸着型酸素濃縮装置において、吸着工程の間に該自動開閉弁手段を間欠的に開くことにより、吸着床に導入した空気の吸着床内での滞留時間を延長し、窒素吸着量を平衡に近づけることにより酸素濃縮効率が向上することを見いだし本願発明に到達した。 即ち、本願発明は、酸素よりも窒素を優先的に吸着し得る吸着剤を充填した少なくとも１個の吸着床と、該吸着床に空気を供給するための空気供給手段と、該吸着床で濃縮された酸素濃縮気体を貯留しておくためのサージタンク手段とを有し、該吸着床と該サージタンク手段を自動開閉弁手段を配した導管手段によって連結した圧力変動吸着型酸素濃縮装置において、該吸着床の吸着工程の間に該自動開閉弁手段を間欠的に開くことを特徴とする酸素濃縮装置を提案するものである。
【００１１】
かかる発明には、該圧力変動吸着型酸素濃縮装置において、該自動開閉弁手段が、吸着工程開始と共に開き、該吸着床の内圧が該サージタンク手段の内圧以下の時点で閉じ、運転圧力範囲における最大圧力以下で再度開き、吸着工程終了と共に閉じる、という２回の開閉を行う酸素濃縮装置が含まれる。
【００１２】
更にかかる発明には、該圧力変動吸着型酸素濃縮装置において、該自動開閉弁手段が、吸着工程開始時よりも早く開き、該吸着床の内圧が該サージタンク手段の内圧以下の時点で閉じ、運転圧力範囲における最大圧力以下で再度開き、吸着工程終了と共に閉じる、という２回の開閉を行う酸素濃縮装置が含まれる。
【００１３】
これらの該自動開閉弁手段が運転圧力範囲の最大圧力以下で再度開く時点は、該最大圧力の７０〜１００％の時点が好ましい。
【００１４】
また、かかる発明には、該圧力変動吸着型酸素濃縮装置において、該自動開閉弁手段が、吸着工程開始と共に開き、該吸着床の内圧が該サージタンク手段の内圧以下の時点で閉じ、運転圧力範囲における最大圧力以下の時点で開いた後、更に該吸着床の内圧が該サージタンク手段の内圧以上の時点で閉じ、該最大圧力以下で開く操作を１回又はそれ以上繰り返し実施し、最後に吸着工程終了と共に閉じる、酸素濃縮装置が含まれる。
【００１５】
更にまた、かかる発明には、該自動開閉弁手段が、吸着工程開始時よりも早く開き、該吸着床の内圧が該サージタンク手段の内圧以下の時点で閉じ、運転圧力範囲における最大圧力以下の時点で開いた後、更に該吸着床の内圧が該サージタンク手段の内圧以上で閉じ、該最大圧力以下で開く操作を１回又はそれ以上実施し、最後に吸着工程終了と共に閉じる、酸素濃縮装置が含まれる。
【００１６】
これらの自動開閉弁手段が該吸着床の内圧が該サージタンク手段の内圧以上で閉じる時点は、運転圧力範囲の最大圧力の７０〜９４％の時点が好ましく、更に好ましくは８５〜９０％がよい。また、該自動開閉弁手段が運転圧力範囲の最大圧力以下で開く時点は、該最大圧力の９５〜１００％の時点が好ましい。
【００１７】
圧力変動吸着型酸素濃縮装置の吸着床の内圧は、通常−1.0〜10.0kgｆ/cm2Ｇ（ゲージ圧）の運転圧力範囲において用いられ、本願装置においてもかかる範囲内で使用し、特に最大圧力は0.5〜4kgｆ/cm2Ｇの範囲で使用し、好ましくは１〜３kgｆ/cm2Ｇの範囲で使用する。
【００１８】
本発明の酸素濃縮装置の吸着床に用いられる吸着剤は、酸素よりも窒素を優先的に吸着し得るものであれば特に限定されないが、モレキュラーシーブゼオライト５Ａ、１３Ｘや、またSiO2/Al2O3比が２.０〜３.０であり且つそのAlO4四面体単位の少なくとも88％以上がリチウムイオンと会合しているＸ型ゼオライトが好ましい。更にこれら３種類の吸着剤を２種或いは全部を組合わせて用いることが出来る。
【００１９】
本発明の酸素濃縮装置においては、これら吸着剤を充填した吸着床の数は１基或いは２基以上の何れであってもよいが、医療用の小型酸素濃縮装置の場合は２基以下が好ましく、特に１基の場合には装置全体を小型化出来る点で優れている。
【００２０】
本発明には、該空気供給手段が、吸着工程においては吸着床に原料空気を供給するためのコンプレッサー手段として機能し、脱着工程においては吸着床中の気体を排出するための真空ポンプ手段として機能する酸素濃縮装置が含まれる。
【００２１】
更に本発明には該吸着床の内圧が大気圧以上で吸着工程を行い、また該内圧が大気圧以下で脱着工程を行う酸素濃縮装置が含まれる。
【００２２】
本発明の装置には濃縮した酸素を一時貯留しておくためのサージタンクを有しており、吸着床の数にかかわらず該タンクを介して使用者に酸素濃縮気体を連続、かつ安定して供給することができる。また本願装置の自動開閉弁手段を吸着工程開始よりも早く開くことにより、該サージタンク手段に貯留された酸素濃縮気体が吸着床に逆流し、吸着床の再加圧、脱着工程でのパージを起こし、又、該吸着床に戻された酸素が吸着剤に吸着されることにより、窒素の吸着が進行する際置換吸着がおこり、窒素吸着帯の進行速度が低下し、本願発明の効果を発揮する上で好ましい。
【００２３】
本願発明の酸素濃縮装置における該自動開閉弁手段の制御方法としては、吸着床及びサージタンクに圧力検知手段を設置し、圧力経時変化を測定しながら自動開閉弁手段の制御を行う方法が用いられる。また実験により得られた圧力経時変化の繰り返しデータを基にタイマー手段により制御する方法を用いることも可能である。
【００２４】
本発明の酸素濃縮装置を使用する場合において、希望の酸素濃度が得られている場合には、全体の吸着圧力を下げる、或いは該自動開閉弁手段の閉鎖時間を短くすることにより部分的吸着圧を下げるなどして該酸素濃縮装置の消費電力量を低減することが出来る。
【００２５】
尚、本発明の酸素濃縮装置の用途としては、特に限定されるものではなく、例えば在宅での医療用途に適している。
【００２６】
【実施例】
以下に本発明の酸素濃縮装置の具体的実施例について必要に応じて図面を用いながら説明する。但し、本発明はこれらの実施例に限定されるものではない。
【００２７】
［実施例１］
SiO2/Al2O3比が２．０〜３．０、且つそのAlO4四面体単位の８８％以上がリチウムカチオンと会合しているＸ型ゼオライトを充填した70mmΦx365mmの大きさの吸着床と、吸着工程においては該吸着床に空気を供給し、脱着工程においてはバルブの切替えにより真空ポンプとして働くコンプレッサー、該吸着床で濃縮された酸素濃縮気体を貯留しておくためのサージタンクとを有し、該吸着床と該サージタンクを自動開閉弁を配した導管によって連結した圧力変動吸着型酸素濃縮装置を製造した。運転範囲における最大圧力を 1.6kgｆ/cm2Ｇに設定した。
【００２８】
かかる装置において、吸脱着の１サイクルを吸着工程１５秒、脱着工程１７秒に設定し、図１及び２に示すように、該自動開閉弁が、吸着工程開始と共に開き、３秒後、該吸着床の内圧と該サージタンクの内圧が等しくなった時点で閉じ、８秒後、吸着床の内圧が最大圧力に達した時点で該自動開閉弁を開き、吸着工程終了と同時に該自動開閉弁を閉じる、一連の開閉パターンを示すように該自動開閉弁をシーケンス制御する酸素濃縮装置を製造した。
【００２９】
［実施例２］
実施例１記載の酸素濃縮装置において、吸脱着の１サイクルを吸着工程１５秒、脱着工程１７秒に設定し、図１及び３に示すように、該自動開閉弁が、吸着工程開始よりも１秒早く開き、吸着工程開始２．５秒後、該吸着床の内圧と該サージタンクの内圧が等しくなった時点で閉じ、７．５秒後、吸着床の内圧が最大圧力に達した時点で該自動開閉弁を開き、吸着工程終了と同時に該自動開閉弁を閉じる、一連の開閉パターンを示すように該自動開閉弁をシーケンス制御する酸素濃縮装置を製造した。
【００３０】
［実施例３］
実施例１記載の酸素濃縮装置において、吸脱着の１サイクルを吸着工程１５秒、脱着工程１７秒に設定し、該自動開閉弁が、吸着工程開始よりも１秒早く開き、吸着工程開始２秒後、該吸着床の内圧と該サージタンクの内圧が等しくなった時点で閉じ、５秒後に該自動開閉弁を開き、吸着工程終了と同時に該自動開閉弁を閉じる、一連の開閉パターンを示すように該自動開閉弁をシーケンス制御する酸素濃縮装置を製造した。
【００３１】
［実施例４］
実施例１記載の酸素濃縮装置において、吸脱着の１サイクルを吸着工程１７秒、脱着工程１８秒に設定し、図１に示すように、該自動開閉弁が、吸着工程開始と共に開き、２．５秒後、該吸着床の内圧と該サージタンクの内圧よりも低い、運転圧力範囲における最高圧の47.5％の時点で閉じ、８．５秒後、吸着床の内圧が最大圧力に達した時点で該自動開閉弁を開き、吸着工程終了と同時に該自動開閉弁を閉じる、一連の開閉パターンを示すように該自動開閉弁をシーケンス制御する酸素濃縮装置を製造した。
【００３２】
［実施例５］
実施例１記載の酸素濃縮装置において、吸脱着の１サイクルを吸着工程１６秒、脱着工程１７秒に設定し、図１に示すように、該自動開閉弁が、吸着工程開始よりも１秒早く開き、吸着工程開始２秒後、該吸着床の内圧と該サージタンクの内圧よりも低い、運転圧力範囲の最高圧の48.7％の時点閉じ、８秒後、吸着床の内圧が最大圧力に達した時点で該自動開閉弁を開き、吸着工程終了と同時に該自動開閉弁を閉じる、一連の開閉パターンを示すように該自動開閉弁をシーケンス制御する酸素濃縮装置を製造した。
【００３３】
［実施例６］
実施例１記載の酸素濃縮装置において、吸脱着の１サイクルを吸着工程１５秒、脱着工程１７秒に設定し、図１に示すように、該自動開閉弁が、吸着工程開始と共に開き、３秒後、該吸着床の内圧と該サージタンクの内圧が等しくなった時点閉じ、６秒後、吸着床の内圧が最大圧力に達した時点で該自動開閉弁を開き、８秒後、最大圧力の90.3％に達した時点で閉じ、１１秒後、99.0％に達した時点で再度開き、吸着工程終了と同時に該自動開閉弁を閉じる、一連の開閉パターンを示すように該自動開閉弁をシーケンス制御する酸素濃縮装置を製造した。
【００３４】
［実施例７］
実施例１記載の酸素濃縮装置において、吸脱着の１サイクルを吸着工程１６秒、脱着工程１７秒に設定し、該自動開閉弁が、吸着工程開始よりも１秒早く開き、吸着工程開始２秒後、該吸着床の内圧と該サージタンクの内圧よりも低い、運転圧力範囲における最大圧力の48.6％の時点で閉じ、８秒後、吸着床の内圧が最大圧力に達した時点で該自動開閉弁を開き、 9.5秒後、最大圧力の87.8％に達した時点で閉じ、１１秒後、最大圧に達した時点で再度開き、吸着工程終了と同時に該自動開閉弁を閉じる、一連の開閉パターンを示すように該自動開閉弁をシーケンス制御する酸素濃縮装置を製造した。
【００３５】
［比較例１］
実施例１記載の酸素濃縮装置において、吸脱着の１サイクルを吸着工程１５秒、脱着工程１７秒に設定し、図１及び４に示すように、該自動開閉弁手段が吸着工程開始と共に開き、吸着工程終了と同時に該自動開閉弁手段を閉じる、一連の開閉パターンを示すように該自動開閉弁手段をシーケンス制御する酸素濃縮装置を製造した。
【００３６】
［比較例２］
実施例１記載の酸素濃縮装置において、吸脱着の１サイクルを吸着工程１５秒、脱着工程１７秒に設定し、図１に示すように、該自動開閉弁手段が吸着工程開始よりも１秒早く開き、吸着工程終了と同時に該自動開閉弁手段を閉じる、一連の開閉パターンを示すように該自動開閉弁手段をシーケンス制御する酸素濃縮装置を製造した。
【００３７】
実施例１の吸着床の内圧は、吸着工程開始により空気供給手段から吸着床へ原料空気が供給され、同時に自動開閉弁手段２が開きサージタンクから吸着床へ酸素濃縮気体が逆流することにより昇圧する第１昇圧過程、吸着床とサージタンクの内圧が同じになった時点で自動開閉弁手段２が閉じ原料空気の供給により昇圧する第２昇圧過程、再度自動開閉弁手段が開き、吸着床への空気供給は継続のままで加圧された吸着床からサージタンク側へ酸素濃縮気体が取出されることによる一過性の減圧を示す酸素濃縮気体取出工程、吸着工程の終了と共に自動開閉弁手段２が閉じ、同時に脱着工程開始による真空ポンプ機能により減圧する、一連の経時変化を繰返した。
【００３８】
実施例２の吸着床の内圧は、吸着工程開始直前に自動開閉弁手段２が開きサージタンクから吸着床へ酸素濃縮気体が逆流することにより昇圧する第１昇圧過程、吸着工程開始による空気供給手段から吸着床へ原料空気の供給とサージタンクから吸着床への逆流の双方による第２昇圧工程、吸着床とサージタンクの内圧が同じになった時点で自動開閉弁手段２が閉じ原料空気の供給により更に昇圧する第３昇圧過程、再度自動開閉弁手段が開き、吸着床への空気供給は継続のままで加圧された吸着床からサージタンク側へ酸素濃縮気体が取出されることによる一過性の減圧を伴う酸素濃縮気体取出工程、吸着工程の終了と共に自動開閉弁手段２が閉じ、同時に脱着工程開始による真空ポンプ機能により減圧する、一連の経時変化を繰返した。
【００３９】
実施例１〜７及び比較例１、２の酸素濃縮装置によって精製した酸素濃縮空気中の酸素濃度、吸着剤の純酸素ガス生産性及び操作圧力範囲におけるバルブ開閉タイミングを表１に示す
【００４０】
【表１】
従来の吸着工程と同時に自動開閉弁手段を開き、吸着工程終了と共に該自動開閉弁手段を閉じる酸素濃縮装置では８８．７％（比較例１）、吸着工程直前に該自動開閉弁手段を開くことによる酸素富化空気の逆流効果により９０．３％（比較例２）の製品酸素濃縮気体が得られていたが、該自動開閉弁手段を間欠的に開くことにより９３〜９４％の酸素濃縮気体を得ることが可能となった。２回に分けて該自動開閉弁手段を間欠的に開く（実施例１）ことにより９３．３％、３回に分けて該自動開閉弁手段を間欠的に開く（実施例６）ことにより９４．３％の製品酸素濃縮気体を得た。また本発明においても吸着工程直前に自動開閉弁手段を開くことにより（実施例２、３、５、７）９３〜９４％の製品酸素濃縮気体を得ることが出来た。
【００４２】
【発明の効果】
本発明の酸素濃縮装置では自動開閉弁手段の開閉パターンを制御し、吸着床の吸着工程の間に該自動開閉弁手段を間欠的に開くことにより、吸着工程における窒素と吸着剤の接触時間が長くなり、窒素の吸着効率が高まり、吸着剤の基本性能である吸着平衡により近づく。それに伴い気相中に残存する酸素量を増加させることにより酸素濃縮気体の回収量を高めるように改善したものである。
【００４３】
この改善がもたらす回収率向上により、酸素濃縮装置の機械的変更に伴う装置の大型化、消費電力量、生産コスト等が上昇することなく、製品ガス中の酸素濃度を高めることが可能となった。また、製品ガス中の酸素濃度を低下させることなく供給空気量を削減することが可能となり、空気供給手段の小型化、動力費の軽減にも効果を奏するものである。
【図面の簡単な説明】
【図１】実施例１〜７、比較例１、２記載の自動開閉弁手段の開閉パターンを示した概略図。
【図２】実施例１の自動開閉弁手段の開閉パターンと吸着床の圧力変動パターンを示した図。
【図３】実施例２の自動開閉弁手段の開閉パターンと吸着床の圧力変動パターンを示した図。
【図４】比較例１の自動開閉弁手段の開閉パターンと吸着床の圧力変動パターンを示した図。
【図５】本発明の酸素濃縮装置における好ましい実施態様例を模式的に示した概略図。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an oxygen concentrator for separating and using an oxygen-enriched gas from the atmosphere. More particularly, the present invention relates to a pressure fluctuation adsorption type oxygen concentrator, and more particularly, to an oxygen concentrator having an improved operation sequence that can supply a user with oxygen-concentrated gas with a small amount of supply gas.
[0002]
[Prior art]
In recent years, the number of patients suffering from respiratory organ diseases such as asthma, emphysema, and chronic bronchitis has been increasing, and one of the most effective treatment methods is oxygen inhalation therapy. Such oxygen inhalation therapy is to allow a patient to inhale oxygen gas or oxygen-enriched air. Oxygen gas cylinders have been used as a supply source of oxygen gas and oxygen-enriched air, but recently, an oxygen concentrator that separates oxygen-enriched gas from the air has been developed, making it convenient and easy to maintain. That's why it has become increasingly popular.
[0003]
Currently, there are a membrane type oxygen concentrator using an oxygen selective permeable membrane and a pressure fluctuation adsorption type oxygen concentrator using an adsorbent capable of preferentially adsorbing nitrogen as an oxygen concentrator, but the present invention is a pressure fluctuation adsorption type. It is intended to improve the oxygen concentrator.
[0004]
The main pressure fluctuation adsorption oxygen concentrators so far include a pressure fluctuation adsorption oxygen concentrator using a compressor. Such an apparatus usually includes an adsorption step for obtaining oxygen-enriched gas by introducing compressed air compressed by a compressor into an adsorption bed filled with an adsorbent capable of preferentially adsorbing nitrogen, and adsorbing nitrogen in a pressurized state. The oxygen-enriched gas is obtained by alternately performing a desorption step of regenerating the adsorption bed by reducing the pressure in the adsorption bed. In this case, a surge tank for temporarily storing the oxygen-enriched gas from the adsorption bed is used, and the oxygen-enriched gas stored in the surge tank is supplied to the patient, and a part of the oxygen is supplied to the adsorption bed. It is often used for purging for re-pressurization of the adsorption bed and regeneration of the adsorption bed.
[0005]
In an adsorption bed of a pressure fluctuation adsorption type oxygen concentrator generally used, molecular sieve zeolite 5A having a separation factor based on a binary adsorption equilibrium of nitrogen and oxygen of about 2.0 to 3.0, or Those filled with 13X are widely used. Recently, in the United States, a zeolite having lithium ions exhibiting a high separation performance having a separation coefficient of 6.0 or more as disclosed in Japanese Patent Publication No. 5-25527 has been developed.
[0006]
These zeolites exhibit a high nitrogen adsorption amount, but have a problem that the adsorption rate is not sufficient in an apparatus in which the adsorption process and the desorption process are quickly switched. The time until the zeolite adsorbent reaches the adsorption equilibrium depends on the type of zeolite, nitrogen concentration and pressure, but generally requires about 5 to 100 minutes. However, small oxygen concentrators for medical use employ a method of repeating adsorption and desorption in a short time of about several tens of seconds in order to secure the product gas flow rate. Only 40-70% of the adsorption capacity is exhibited. Therefore, in such an oxygen concentrator, the control rate of the nitrogen adsorption rate of the adsorbent is increased, and a high-performance nitrogen adsorbent with improved adsorption amount per unit weight and selectivity indicating the performance of the adsorbent has been developed. Even in the present situation, there is a limit to improving the oxygen concentration efficiency.
[0007]
Due to the above problems, when the oxygen concentration in the oxygen-concentrated gas purified by the oxygen concentrator does not reach the desired concentration range, the adsorbent filling amount is increased to increase the adsorption capacity of the adsorption bed. To improve the oxygen concentrator mechanically, for example, increase the air supply capacity per unit time by increasing the supply capacity of the air supply means or decreasing the flow resistance. As a result, the product gas concentration was secured. However, such a method cannot avoid problems such as an increase in the size of the apparatus, power consumption, and an increase in production cost.
[0008]
Further, JP-A-1-288313 and JP-A-2-11016 disclose a method for improving the oxygen concentration in the product gas by controlling the gas flow rate in the adsorption bed. That is, by introducing the raw material air introduced into the adsorption bed and the product gas introduced into the adsorption bed for purging intermittently, that is, by using a pulse flow, the gas flow velocity in the adsorption bed is smoothed, and the product gas It is revealed that the concentration is improved. However, this method has a drawback that a sufficient amount of product gas per hour cannot be secured, and the productivity described in Example 2 of Japanese Patent Laid-Open No. 2-115016: 23.7 L · O 2 / kg · hr Even in a small oxygen concentrator for medical use, the amount of oxygen gas produced is not sufficient.
[0009]
[Problems to be solved by the invention]
The object of the present invention is to improve the oxygen concentration efficiency in the adsorption bed and improve the oxygen concentration of the product gas without mechanical change of the pressure fluctuation adsorption type oxygen concentrator, thereby reducing the amount of supply air, It is to realize a reduction in the size of the supply means and a reduction in power consumption of the apparatus.
[0010]
[Means for Solving the Problems]
As a result of intensive studies aimed at solving such problems, the inventor of the present application has an adsorbent bed filled with an adsorbent and surge tank means for storing oxygen-enriched gas concentrated in the adsorbent bed. In the pressure fluctuation adsorption type oxygen concentrating apparatus in which the adsorption bed and the surge tank means are connected by a conduit means having an automatic opening / closing valve means, the automatic opening / closing valve means is intermittently opened during the adsorption process, It has been found that the oxygen concentration efficiency is improved by extending the residence time of the air introduced into the adsorption bed in the adsorption bed and bringing the nitrogen adsorption amount close to equilibrium. That is, the present invention comprises at least one adsorption bed filled with an adsorbent capable of preferentially adsorbing nitrogen over oxygen, air supply means for supplying air to the adsorption bed, and concentration in the adsorption bed. In the pressure fluctuation adsorption type oxygen concentrating apparatus having a surge tank means for storing the oxygen enriched gas, and connecting the adsorption bed and the surge tank means by a conduit means having an automatic opening / closing valve means, The present invention proposes an oxygen concentrator characterized by intermittently opening the automatic opening / closing valve means during the adsorption step of the adsorption bed.
[0011]
In this invention, in the pressure fluctuation adsorption type oxygen concentrator, the automatic opening / closing valve means opens at the start of the adsorption process, and closes when the internal pressure of the adsorption bed is equal to or lower than the internal pressure of the surge tank means, and in the operating pressure range. It includes an oxygen concentrator that opens and closes twice, opening again below the maximum pressure and closing with the end of the adsorption process.
[0012]
Further, in the present invention, in the pressure fluctuation adsorption type oxygen concentrator, the automatic opening / closing valve means opens earlier than at the start of the adsorption process, and closes when the internal pressure of the adsorption bed is equal to or lower than the internal pressure of the surge tank means, It includes an oxygen concentrator that opens and closes twice, opening again below the maximum pressure in the operating pressure range and closing with the end of the adsorption process.
[0013]
The point in time when the automatic opening / closing valve means opens again below the maximum pressure in the operating pressure range is preferably 70 to 100% of the maximum pressure.
[0014]
Further, according to the invention, in the pressure fluctuation adsorption type oxygen concentrator, the automatic opening / closing valve means is opened at the start of the adsorption process, and is closed when the internal pressure of the adsorption bed is equal to or lower than the internal pressure of the surge tank means. After opening at a time below the maximum pressure in the range, the operation of closing the internal pressure of the adsorption bed when the internal pressure of the surge tank means is higher than the internal pressure of the surge tank means and opening it below the maximum pressure is repeated once or more, and finally An oxygen concentrator is included that closes with the end of the adsorption process.
[0015]
Furthermore, in this invention, the automatic opening / closing valve means opens earlier than at the start of the adsorption process, and closes when the internal pressure of the adsorption bed is less than or equal to the internal pressure of the surge tank means, and less than the maximum pressure in the operating pressure range. An oxygen concentrating device that is opened at the time, and further closes when the internal pressure of the adsorption bed is equal to or higher than the internal pressure of the surge tank means, and opens one or more times below the maximum pressure, and finally closes at the end of the adsorption step. Is included.
[0016]
The point in time when these automatic opening / closing valve means closes when the internal pressure of the adsorption bed exceeds the internal pressure of the surge tank means is preferably 70 to 94% of the maximum pressure in the operating pressure range, more preferably 85 to 90%. . The time when the automatic opening / closing valve means opens below the maximum pressure in the operating pressure range is preferably 95 to 100% of the maximum pressure.
[0017]
The internal pressure of the adsorption bed of the pressure fluctuation adsorption-type oxygen concentrator is normally used in the operating pressure range of -1.0 to 10.0 kgf / cm 2 G (gauge pressure), and is also used within this range in the device of the present application. Is used in the range of 0.5 to 4 kgf / cm 2 G, preferably in the range of 1 to 3 kgf / cm 2 G.
[0018]
The adsorbent used in the adsorption bed of the oxygen concentrator of the present invention is not particularly limited as long as it can preferentially adsorb nitrogen over oxygen, but molecular sieve zeolite 5A, 13X, or SiO 2 / Al 2 X-type zeolite having an O 3 ratio of 2.0 to 3.0 and at least 88% of the AlO 4 tetrahedral units associated with lithium ions is preferred. Furthermore, these three kinds of adsorbents can be used in combination of two or all of them.
[0019]
In the oxygen concentrator of the present invention, the number of adsorbent beds filled with these adsorbents may be one or two or more, but in the case of a small medical oxygen concentrator, two or less are preferable. In particular, in the case of a single unit, the entire apparatus can be reduced in size.
[0020]
In the present invention, the air supply means functions as a compressor means for supplying the raw material air to the adsorption bed in the adsorption process, and functions as a vacuum pump means for discharging the gas in the adsorption bed in the desorption process. An oxygen concentrator is included.
[0021]
Furthermore, the present invention includes an oxygen concentrator that performs the adsorption step when the internal pressure of the adsorbent bed is equal to or higher than atmospheric pressure, and performs the desorption step when the internal pressure is equal to or lower than atmospheric pressure.
[0022]
The apparatus of the present invention has a surge tank for temporarily storing concentrated oxygen, and continuously and stably supplies oxygen-enriched gas to the user through the tank regardless of the number of adsorption beds. Can be supplied. In addition, by opening the automatic open / close valve means of the apparatus of the present application earlier than the start of the adsorption process, the oxygen-enriched gas stored in the surge tank means flows back to the adsorption bed, and the adsorption bed is re-pressurized and purged in the desorption process. The oxygen adsorbed to the adsorbent bed is adsorbed by the adsorbent, so that substitution adsorption occurs when the adsorption of nitrogen proceeds, and the progress rate of the nitrogen adsorption zone decreases, and the effect of the present invention is exhibited. This is preferable.
[0023]
As a method for controlling the automatic opening / closing valve means in the oxygen concentrator of the present invention, a method is used in which pressure detection means is installed in the adsorption bed and the surge tank, and the automatic opening / closing valve means is controlled while measuring changes with time in pressure. . It is also possible to use a method of controlling by timer means based on repeated data of pressure change with time obtained by experiments.
[0024]
In the case of using the oxygen concentrator of the present invention, when the desired oxygen concentration is obtained, the partial adsorption pressure is reduced by lowering the entire adsorption pressure or shortening the closing time of the automatic opening / closing valve means. For example, the power consumption of the oxygen concentrator can be reduced.
[0025]
The use of the oxygen concentrator of the present invention is not particularly limited and is suitable for medical use at home, for example.
[0026]
【Example】
Specific examples of the oxygen concentrator of the present invention will be described below with reference to the drawings as necessary. However, the present invention is not limited to these examples.
[0027]
[Example 1]
An adsorbent bed having a size of 70 mmΦx365 mm packed with X-type zeolite having a SiO 2 / Al 2 O 3 ratio of 2.0 to 3.0 and 88% or more of the AlO 4 tetrahedral units associated with lithium cations; In the adsorption process, air is supplied to the adsorption bed, and in the desorption process, a compressor that works as a vacuum pump by switching a valve, and a surge tank for storing the oxygen-enriched gas concentrated in the adsorption bed are provided. Thus, a pressure fluctuation adsorption type oxygen concentrator was produced in which the adsorption bed and the surge tank were connected by a conduit having an automatic opening / closing valve. The maximum pressure in the operating range was set to 1.6 kgf / cm 2 G.
[0028]
In such an apparatus, one cycle of adsorption / desorption is set to 15 seconds for the adsorption process and 17 seconds for the desorption process, and as shown in FIGS. 1 and 2, the automatic open / close valve opens with the start of the adsorption process, and after 3 seconds, It closes when the internal pressure of the floor and the internal pressure of the surge tank become equal. After 8 seconds, the automatic open / close valve is opened when the internal pressure of the adsorption bed reaches the maximum pressure. An oxygen concentrator for controlling the automatic open / close valve in sequence so as to show a series of open / close patterns was manufactured.
[0029]
[Example 2]
In the oxygen concentrator described in Example 1, one cycle of adsorption / desorption is set to 15 seconds for the adsorption process and 17 seconds for the desorption process. As shown in FIGS. Opens 2.5 seconds later and closes when the internal pressure of the adsorption bed and the internal pressure of the surge tank become equal 2.5 seconds after the start of the adsorption process, and 7.5 seconds later when the internal pressure of the adsorption bed reaches the maximum pressure An oxygen concentrator was produced in which the automatic open / close valve was opened and the automatic open / close valve was closed at the same time as the adsorption process was completed.
[0030]
[Example 3]
In the oxygen concentrator described in Example 1, one cycle of adsorption / desorption is set to 15 seconds for the adsorption process and 17 seconds for the desorption process, and the automatic opening / closing valve opens 1 second earlier than the start of the adsorption process, and 2 seconds from the start of the adsorption process. After that, when the internal pressure of the adsorption bed and the internal pressure of the surge tank become equal, the automatic open / close valve is opened after 5 seconds, and the automatic open / close valve is closed simultaneously with the end of the adsorption process. In addition, an oxygen concentrator for controlling the automatic open / close valve in sequence was manufactured.
[0031]
[Example 4]
1. In the oxygen concentrator described in Example 1, one cycle of adsorption / desorption is set to 17 seconds for the adsorption process and 18 seconds for the desorption process, and as shown in FIG. After 5 seconds, it is closed at 47.5% of the maximum pressure in the operating pressure range, which is lower than the internal pressure of the adsorption bed and the surge tank, and after 8.5 seconds, the internal pressure of the adsorption bed reaches the maximum pressure. The oxygen concentrator for controlling the automatic open / close valve in sequence so as to show a series of open / close valves is manufactured.
[0032]
[Example 5]
In the oxygen concentrator described in Example 1, one cycle of adsorption / desorption is set to 16 seconds for the adsorption process and 17 seconds for the desorption process, and as shown in FIG. 1, the automatic open / close valve is 1 second earlier than the start of the adsorption process. 2 seconds after the start of the adsorption process, it closes at 48.7% of the maximum pressure in the operating pressure range, which is lower than the internal pressure of the adsorption bed and the surge tank. After 8 seconds, the internal pressure of the adsorption bed reaches the maximum pressure. At that time, the automatic open / close valve was opened, and the automatic open / close valve was closed simultaneously with the end of the adsorption process. Thus, an oxygen concentrator was produced that controlled the automatic open / close valve in sequence so as to show a series of open / close patterns.
[0033]
[Example 6]
In the oxygen concentrator described in Example 1, one cycle of adsorption / desorption is set to 15 seconds for the adsorption process and 17 seconds for the desorption process, and as shown in FIG. After that, when the internal pressure of the adsorption bed and the internal pressure of the surge tank become equal, it is closed, and after 6 seconds, the automatic open / close valve is opened when the internal pressure of the adsorption bed reaches the maximum pressure. Closes when it reaches 90.3%, reopens after 11 seconds and when it reaches 99.0%, and closes the automatic open / close valve simultaneously with the end of the adsorption process. Sequence control of the automatic open / close valve to show a series of open / close patterns An oxygen concentrator was produced.
[0034]
[Example 7]
In the oxygen concentrator described in Example 1, one cycle of adsorption / desorption is set to 16 seconds for the adsorption process and 17 seconds for the desorption process, and the automatic opening / closing valve opens 1 second earlier than the start of the adsorption process, and 2 seconds from the start of the adsorption process. After that, it closes at 48.6% of the maximum pressure in the operating pressure range, which is lower than the internal pressure of the adsorption bed and the surge tank, and after 8 seconds the automatic opening and closing when the internal pressure of the adsorption bed reaches the maximum pressure A series of open / close patterns that open the valve, close when it reaches 87.8% of the maximum pressure after 9.5 seconds, open again when the maximum pressure is reached after 11 seconds, and close the automatic open / close valve at the end of the adsorption process Thus, an oxygen concentrator for controlling the automatic open / close valve in sequence was manufactured.
[0035]
[Comparative Example 1]
In the oxygen concentrator described in Example 1, one cycle of adsorption / desorption is set to 15 seconds for the adsorption process and 17 seconds for the desorption process, and as shown in FIGS. 1 and 4, the automatic opening / closing valve means opens with the start of the adsorption process, An oxygen concentrator was produced in which the automatic open / close valve means was closed at the same time as the adsorption process was completed, and the automatic open / close valve means was sequence-controlled so as to show a series of open / close patterns.
[0036]
[Comparative Example 2]
In the oxygen concentrator described in Example 1, one cycle of adsorption / desorption is set to 15 seconds for the adsorption process and 17 seconds for the desorption process, and as shown in FIG. 1, the automatic opening / closing valve means is 1 second earlier than the start of the adsorption process. An oxygen concentrator that opens and closes the automatic open / close valve means simultaneously with the end of the adsorption process and controls the automatic open / close valve means in sequence so as to show a series of open / close patterns was manufactured.
[0037]
The internal pressure of the adsorption bed of Example 1 is increased by supplying raw material air from the air supply means to the adsorption bed at the start of the adsorption process, and simultaneously opening the automatic opening / closing valve means 2 and causing the oxygen-enriched gas to flow backward from the surge tank to the adsorption bed. In the first pressurizing process, when the internal pressure of the adsorption bed and the surge tank becomes the same, the automatic open / close valve means 2 is closed and the pressure is increased by supplying the raw material air. Oxygen-enriched gas extraction process showing temporary depressurization by extracting oxygen-enriched gas from the pressurized adsorbent bed to the surge tank while the air supply continues, and automatic opening / closing valve means at the end of the adsorption process 2 was closed, and at the same time, a series of changes over time was repeated in which the pressure was reduced by the vacuum pump function by starting the desorption process.
[0038]
The internal pressure of the adsorption bed of Example 2 is the first pressure increasing process in which the automatic open / close valve means 2 is opened immediately before the adsorption process starts and the oxygen-enriched gas flows backward from the surge tank to the adsorption bed, and the air supply means by the start of the adsorption process. The second pressurization step by both the supply of raw material air to the adsorption bed and the backflow from the surge tank to the adsorption bed, the automatic open / close valve means 2 is closed when the internal pressures of the adsorption bed and the surge tank become the same, and the supply of raw material air In the third pressurizing process in which the pressure is further increased, the automatic opening / closing valve means is opened again, and the oxygen concentration gas is taken out from the pressurized adsorbing bed to the surge tank side while the air supply to the adsorbing bed is continued. The automatic on-off valve means 2 was closed at the end of the oxygen-concentrated gas extraction process and the adsorption process with a characteristic pressure reduction, and at the same time, a series of changes over time was repeated by the vacuum pump function by the start of the desorption process.
[0039]
Table 1 shows the oxygen concentration in the oxygen-enriched air purified by the oxygen concentrators of Examples 1 to 7 and Comparative Examples 1 and 2, the pure oxygen gas productivity of the adsorbent, and the valve opening / closing timing in the operating pressure range.
[Table 1]
In the oxygen concentrator that opens the automatic open / close valve means simultaneously with the conventional adsorption process and closes the automatic open / close valve means at the end of the adsorption process, 88.7% (Comparative Example 1) opens the automatic open / close valve means immediately before the adsorption process. 90.3% (comparative example 2) of product oxygen-enriched gas was obtained by the reverse flow effect of oxygen-enriched air produced by the above. It became possible to get. 93.3% by intermittently opening the automatic opening / closing valve means in two steps (Example 1) 94 by opening the automatic opening / closing valve means intermittently in three times (Example 6) A 3% product oxygen enriched gas was obtained. Also in the present invention, 93 to 94% product oxygen-enriched gas could be obtained by opening the automatic opening / closing valve means immediately before the adsorption step (Examples 2, 3, 5, 7).
[0042]
【The invention's effect】
In the oxygen concentrator of the present invention, the contact time between the nitrogen and the adsorbent in the adsorption process is controlled by controlling the open / close pattern of the automatic open / close valve means and intermittently opening the automatic open / close valve means during the adsorption process of the adsorption bed. The adsorption efficiency of nitrogen increases, and the adsorption equilibrium, which is the basic performance of the adsorbent, approaches. Accordingly, the amount of oxygen remaining in the gas phase is increased to improve the recovery amount of the oxygen-enriched gas.
[0043]
The improvement in the recovery rate brought about by this improvement makes it possible to increase the oxygen concentration in the product gas without increasing the size of the device, power consumption, production costs, etc. associated with the mechanical change of the oxygen concentrator. . In addition, the amount of supplied air can be reduced without lowering the oxygen concentration in the product gas, and the air supply means can be reduced in size and the power cost can be reduced.
[Brief description of the drawings]
FIG. 1 is a schematic view showing opening / closing patterns of automatic opening / closing valve means described in Examples 1 to 7 and Comparative Examples 1 and 2;
FIG. 2 is a diagram showing an opening / closing pattern of an automatic opening / closing valve means and a pressure fluctuation pattern of an adsorbent bed according to the first embodiment.
FIG. 3 is a diagram showing an opening / closing pattern of an automatic opening / closing valve means and a pressure fluctuation pattern of an adsorbent bed according to a second embodiment.
4 is a diagram showing an opening / closing pattern of an automatic opening / closing valve means and a pressure fluctuation pattern of an adsorbent bed in Comparative Example 1. FIG.
FIG. 5 is a schematic view schematically showing a preferred embodiment example in the oxygen concentrator of the present invention.
Claims (6)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23252595A JP3793256B2 (en) | 1995-09-11 | 1995-09-11 | Oxygen concentrator |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23252595A JP3793256B2 (en) | 1995-09-11 | 1995-09-11 | Oxygen concentrator |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0977502A JPH0977502A (en) | 1997-03-25 |
| JP3793256B2 true JP3793256B2 (en) | 2006-07-05 |
Family
ID=16940707
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP23252595A Expired - Fee Related JP3793256B2 (en) | 1995-09-11 | 1995-09-11 | Oxygen concentrator |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3793256B2 (en) |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6146447A (en) * | 1998-11-25 | 2000-11-14 | Air Products And Chemicals, Inc. | Oxygen generation process and system using single adsorber and single blower |
| EP1018359A3 (en) * | 1998-11-25 | 2002-09-04 | Air Products And Chemicals, Inc. | Pressure swing adsorption process and system with product storage tank(s) |
| US6096115A (en) * | 1998-11-25 | 2000-08-01 | Air Products And Chemicals, Inc. | Pressure swing adsorption process and system utilizing two product storage tanks |
| US6102985A (en) * | 1998-11-25 | 2000-08-15 | Air Products And Chemicals, Inc. | Pressure swing adsorption process and system with dual product storage tanks |
| US6156101A (en) * | 1999-02-09 | 2000-12-05 | Air Products And Chemicals, Inc. | Single bed pressure swing adsorption process and system |
| US6183538B1 (en) | 1999-02-09 | 2001-02-06 | Air Products And Chemicals, Inc. | Pressure swing adsorption gas flow control method and system |
| US6425938B1 (en) * | 2000-11-01 | 2002-07-30 | Air Products And Chemicals, Inc. | Single bed pressure swing adsorption process |
| JP5139657B2 (en) * | 2006-09-11 | 2013-02-06 | 帝人ファーマ株式会社 | Pressure fluctuation adsorption type oxygen concentrator |
-
1995
- 1995-09-11 JP JP23252595A patent/JP3793256B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0977502A (en) | 1997-03-25 |
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