JP3654477B2 - Bulk separation of gases by parametric gas chromatography. - Google Patents

Description

【００３１】
【発明の実施の形態】
本発明の方法は吸着剤カラム一の端から他端へ原料混合ガスを通じ、出口端部から一定周期毎に例えば酸素と窒素が交互に出てくる点では常用ガスクロマトグラフィー操作に似ているが、次の点で異なる。
▲１▼キャリヤーガスとして第３のガス［成分（Ａ）、成分（Ｂ）以外のガス］を使用していない。ガスクロマトグラフィーで酸素−窒素分離を行うときは、非吸着性のＨｅガスなどを使用している。
▲２▼本発明の方法においてはキャリヤーガスに相当するガスは成分（Ａ）、成分（Ｂ）またはこれらの混合ガスである。また一定流速で供給するものでない。
▲３▼上記▲２▼に示す本発明の方法におけるキャリヤーガスの組成・圧力・温度・流量等は一定のパターンで周期的に変動し、パラメーター変動的である。
また、本発明の方法は圧力変動による吸脱着効果を利用する循環操作であって常用ＰＳＡ（圧力変動吸着法）と似ているが、全操作を通じ、ガスの流れは一方向（並流）のみであるので、並流と向流の２つの操作が結合した常用ＰＳＡとは異なる。
【００３２】
以下に常用ＰＳＡよりパラメトリックガスクロマトグラフィーへ到る経過を簡単に記す。空気より酸素製造を例にとって説明する。
常用ＰＳＡの基本プロセスは次の４つの個別操作より成る。一つの塔に着目して、▲１▼原料空気加圧→▲２▼製品酸素取出→▲３▼向流減圧→▲４▼パージそして▲１▼へ戻る。
常用ＰＳＡには約２０００件の特許があるが、その殆どは上記４工程プロセスの変形態様である。
次に代表的なプロセスを説明する。
1) ▲４▼のパージ工程の後で製品酸素の一部を向流方向（還流）に流し、塔内圧力を操作の中間圧以上まで復圧させる。
2) 減圧を例えば並流２〜３段と向流１段とに分けて行い、並流減圧ガスは別の塔へ回収し、向流減圧ガスは大気へ放出する。
3) ▲２▼と▲３▼の工程の間および▲４▼と▲１▼の工程の間に均圧操作を入れて塔を減圧または昇圧する。
4) 上記▲３▼の向流減圧をポンプを用いて促進する（真空法と称す）。操作の最低圧が真空になる。
【００３３】
上記常用ＰＳＡにおける非効率の主因（収率低下）は主として前記▲３▼と▲４▼の“向流”操作にあり、“向流”減圧操作で有効成分の酸素が系外へ放出される。
この酸素ロスをできるだけ減らすため、長年に亘り、幾多の改良が加えられ、今日迄多数のＰＳＡ特許が提案されることになった。
【００３４】
そこで本発明者はパルス流制御法の手法の一部を応用して前記▲３▼と▲４▼の向流操作におけるガスの量と純度の時々刻々の変化を詳細に追跡した結果、上記▲３▼の向流減圧ロスは上記▲４▼のパージロスに比較して格段に大きいこと、向流減圧を初期、中期、後期の３ステップに分けたとき、初期ロスが大きいこと、パージ効果は大きく、かつパージロスは少ないので、この効果を積極的に活用すべきであることなどが判明した。
【００３５】
減圧ロスの回収のため、減圧を並流と向流のいくつかの個別操作に分割して“多段化”し、有効成分に富んだ減圧ガスをシステム内に回収することは先行技術で確立しているが、この場合塔数が３〜４個必要となり、構成が複雑化する。
そこで本発明においては、減圧はすべて並流方向とし、有効成分は原則としてすべて回収すること、吸着塔の再生には“パージ”を積極的に活用すること、パージ損失を防止するため、塔内濃度勾配は個別操作間を通じて一定に保持し、混合によるエントロピーロスを最小にすること、また特に大容量機においては圧力エネルギーをできるだけ回収すること、また、構成材料が鉄と石（ゼオライト）で、深冷法のごとき高級材料（銅、アルミ）は全く使用しないことなどにより、省エネ、省資材性に優れ、かつ酸素−窒素が併産できるという、従来ＰＳＡにない特長が得られ、将来の廃棄処分費等のすべてを含めた総合効率は従来の空気分離方法（深冷法、常用ＰＳＡ）に比較して格段に向上する。
【００３６】
空気分離を例にとって、本発明の方法を具体的に説明する。
図１は本発明の方法を実施するための基本システムを示す。
この基本システムは、ポンプ（１）、前処理装置（３）、分離装置（またはシステム）（５）の３部分と接続配管（２，４，６）、製品取出弁（２７，２８）から成る。
1) 原料空気はポンプ（１）により加圧され、管路（２）を経て前処理装置（３）へ送られる。
2) 原料空気中の水分、炭酸ガス等は前処理装置（３）にて除かれ、乾燥空気（ＤＡ）として管路（４）へ送出される。前処理方法は、吸着式、冷媒式、膜式またはこれらの併用式の何れであってもよいが、総括効率の低下を来さないよう、低価格、省エネで製品ロスの少ないものを選択することが好ましい。
3) 乾燥空気（ＤＡ）は分離装置（またはシステム）（５）へ送られる。ＤＡはこの装置（５）で酸素と窒素に分離され、一定時間毎、交互に管路（６）に送出される。
4) 管路（６）に接続する自動弁（２７）と（２８）を一定時間毎に交互に開閉することにより製品酸素（Ｏ₂ ）、製品窒素または排窒素（Ｎ₂ ）として捕集され、製品ガスは各弁の下流に接続される製品貯槽（記載せず）に貯蔵され、そこから消費端へ送られる。
そして分離態様としては、下記１〜３の場合がある。
１．酸素のみ製品とし、排窒素は大気へ放出する。
２．窒素のみ製品とし、排酸素は大気へ放出する。
３．酸素−窒素併産製品とする。
但し、窒素純度が９０％以上のときと、９９％以上のときの２通りがある。
【００３７】
本発明の方法の主旨は、図１に示す分離装置または吸着分離システム（５）における次に示す操作手順にある。
なお吸着分離システム（５）には、図４〜６に示す吸着分離システム内に前処理装置を含まないもの（大型機対象）、図７〜８に示す吸着分離システム内に前処理装置を含むもの（中および小型機対象）、その他分離仕様により異なるものなどいくつかの基本態様があるが、基本操作（本発明の方法）は同じである。
図７に示す吸着分離システムは酸素のみ製品とするシステム例であり、図８に示す吸着分離システムは酸素と低純度窒素（９０％以上）を製品とするシステム例であり、図９に示す吸着分離システムは酸素と高純度窒素（９９％以上）を製品とするシステム例である。
【００３８】
本発明の気体のバルク分離方法を、図４（Ａ）に示す２塔構成の吸着分離システム（装置）を用いて空気より酸素と窒素を分離する例により説明する。
図４（Ｂ）は、後に詳述するが、圧力エネルギー回収手段（ＥＸ）を用いて降圧過程の圧力エネルギーを膨張機関または発電機で回収する場合のシステム例を示す。
図２（Ａ）は、［吸着塔（Ａ）および吸着塔（Ｂ）内の圧力〜時間］関係を示す圧力シーケンスであり、図２（Ｂ）は各工程▲１▼〜▲６▼の終期における吸着塔（Ａ）および吸着塔（Ｂ）内の気相酸素濃度を模型的に示す説明図である。なお、図２（Ｂ）中の記号１〜４は酸素濃度を示し、１は酸素濃度２１％以下、２は酸素濃度２１％、３は酸素濃度２１〜９０％、４は酸素濃度９０％以上を示す。この記号１〜４と酸素濃度の関係をまとめて表１に示す。
【００３９】
【表１】

【００４０】
本発明においては、吸着塔（Ａ）、吸着塔（Ｂ）において次の工程▲１▼〜▲６▼の個別操作を順次繰返すことにより、吸着塔出口端部から酸素と窒素が一定時間間隔をおいて交互に取出される。
なお、吸着分離システムの供給空気は予め前処理装置で水分、炭酸ガス等を除去した“乾燥”空気とする。
【００４１】
次に工程▲１▼〜▲６▼順序を示す。
▲１▼ 原料加圧
原料空気はポンプにて加圧され、吸着塔（Ａ）へ入口端より送入される。そして吸着塔（Ａ）の圧力を中間圧（Ｐ_M ）から上昇さす。
出口端部からは酸素リッチガスが取出され、最低操作圧（Ｐ_L ）下にある吸着塔（Ｂ）へ、パージガスとして並流供給される。
▲２▼ 製品送出
吸着塔（Ａ）内圧力が最高操作圧（Ｐ_H ）に到達したら、原料空気の送入を停止する。最高操作圧（Ｐ_H ）近傍で製品取出弁が開放され、製品酸素が取出され、図示しない製品貯槽へ送られる。
また、製品酸素の一部は吸着塔（Ｂ）のパージガスまたは再加圧用のガスとして並流供給される。
▲３▼ 並流減圧（１）
吸着塔（Ａ）の均圧弁を開放して、吸着塔（Ａ）と吸着塔（Ｂ）を並流接続する。この操作により吸着塔（Ａ）内圧力は降下し、吸着塔（Ｂ）内圧力は上昇する。
この操作は通常、２つの塔の圧力が平衡化するまで行うが、（均圧）、平衡化の途中で停止する場合もある（部分均圧）。
▲４▼ 並流減圧（２）
上記工程終了後、吸着塔（Ａ）の出口端を大気へ開放し、塔内残留ガスを大気へ並流放出し、またさらに真空ポンプにより吸引し大気圧以下にし、最低操作圧（Ｐ_L ）にする。
▲５▼ パージ
最低の操作圧下にある吸着塔（Ａ）に対して、吸着塔（Ｂ）出口端部から酸素リッチガスを並流送入し、吸着塔（Ａ）内に残留した窒素を並流パージする。
▲６▼ 再加圧
【００４２】
上記工程▲１▼〜▲６▼を終了後、工程▲３▼と同様、吸着塔（Ａ）と吸着塔（Ｂ）を並流接続し、吸着塔（Ａ）は中間圧（Ｐ_M ）迄復圧するとともに吸着塔（Ｂ）は降圧する。
以上の工程▲１▼−▲６▼の操作を１サイクル操作（１サイクル時間、Ｔ秒）と云う。２塔構成のときは、吸着塔（Ａ）と吸着塔（Ｂ）はＴ／２時間遅れて同一の操作を繰返す。
３塔構成のときは、吸着塔（Ａ）、吸着塔（Ｂ）、吸着塔（Ｃ）はＴ／３時間遅れて同一の操作を繰返す。
【００４３】
図２（Ｂ）により吸着塔（Ａ）および吸着塔（Ｂ）内の酸素濃度の変化を説明する。
工程▲１▼、工程▲２▼において、
吸着塔（Ａ）に、原料空気を送入する（矢印で示す）ことにより吸着塔（Ａ）内ガス濃度分布は入口−出口側に向かって図２（Ｂ）に示したように２−３−４となる。以下同様の記載方法とする。
出口端部の製品酸素は製品として捕集される。一部は吸着塔（Ｂ）へパージガスとして供給される（矢印で示す）。
【００４４】
工程▲３▼、工程▲４▼の並流減圧工程により窒素の脱着が始まり、吸着塔（Ａ）内ガスの濃度分布は図２（Ｂ）に示したように１−２−３から１−１−２のごとく変化する。
空気濃度（Ｏ₂ ＝２１％）以下のガスは排窒素として、大気中へ放出する（粗窒素として回収してもよい）。
【００４５】
工程▲５▼（パージ）において、
吸着塔（Ａ）入口端部から酸素が並流方向に導入されることにより、入口端部に吸着されている窒素から順次脱着が始まり、出口端部方向へ押しやられる。
吸着塔（Ａ）内気相濃度は図２（Ｂ）に示したように１−１−２から４−１−１のごとく変化する。
２塔構成システムでは、この工程で濃度段差が生じるので、入口端部より乾燥空気（ＤＡ）をリークさせて、１−１−２→２−１−１→４−２−１のごとくしてもよい。
【００４６】
工程▲６▼（再加圧または復圧）
吸着塔（Ｂ）を減圧しつつ、吸着塔（Ａ）へ並流供給することにより吸着塔（Ａ）内の酸素濃度は図２（Ｂ）に示したように４−１−１から３−４−１のごとく変化する。次第に出口端へ酸素リッチガスが移動する。
工程▲６▼に引続き工程▲１▼（原料空気供給）が始まり図２（Ｂ）に示したように、３−４−１から２−３−４のごとく圧力上昇とともに、出口端部は酸素リッチになる。
吸着塔（Ａ）の昇圧工程においては、出口端部へ向かって次第に酸素リッチになるよう、また降圧工程においては、出口端部へ向かって次第に窒素リッチになるよう配慮して、吸着塔（Ａ）、吸着塔（Ｂ）間の気体移動量を制御する。
また吸着塔（Ａ）と吸着塔（Ｂ）、吸着塔（Ｂ）と吸着塔（Ａ）を並流接続するとき、接続部で濃度段差がおきないよう（濃度差による混合がおきないよう）操作する。
【００４７】
本発明の気体のバルク分離方法を、図５に示す３塔構成の吸着分離システム（装置）を用いて空気より酸素と窒素を分離する例により説明する。
図３（Ａ）は、［吸着塔（Ａ）、吸着塔（Ｂ）および吸着塔（Ｃ）内の圧力〜時間］関係を示す圧力シーケンスであり、図３（Ｂ）は各工程▲１▼〜▲６▼の終期における吸着塔（Ａ）、吸着塔（Ｂ）および吸着塔（Ｃ）内の気相酸素濃度を模型的に示す説明図である。なお、図３（Ｂ）中の記号１〜４は酸素濃度を示し、１は酸素濃度２１％以下、２は酸素濃度２１％、３は酸素濃度２１〜９０％、４は酸素濃度９０％以上を示す。この記号１〜４と酸素濃度の関係をまとめて前記表１に示す。
【００４８】
この場合においても原料ガスは前処理すみの乾燥空気である。前記の２塔構成システムにおけると同様、吸着塔（Ａ）、吸着塔（Ｂ）、吸着塔（Ｃ）の各塔はＴ／３時間おくれて次の▲１▼〜▲６▼の６工程操作を順次繰返す。
▲１▼原料ガス加圧→製品酸素送出
▲２▼並流減圧（１）
▲３▼並流減圧（２）
▲４▼パージ
▲５▼再加圧（１）
▲６▼再加圧（２）
【００４９】
３塔構成システムにおける操作と２塔構成システムにおける操作の対比を表２に示す。
【００５０】
【表２】

【００５１】
即ち、２塔構成システムにおける▲１▼、▲２▼の操作が３塔構成システムにおいては１つの個別操作▲１▼になり、２塔構成システムにおける▲６▼の操作が３塔構成システムでは▲５▼と▲６▼の２つの個別操作になる。
【００５２】
次に、前記２塔構成システムの説明と重複しないよう３塔構成システムの個別操作を説明する。
吸着塔（Ａ）に着目して、
工程▲１▼では原料空気を吸着塔（Ａ）へ加圧送入し、吸着塔（Ａ）内圧力を上昇させつつ、製品酸素を取出す。残部は吸着塔（Ｂ）内圧力をＰ_L →Ｐ_M1（中間圧（１））へ加圧する。
工程▲２▼では原料空気の送入を続行しつつ出口端部より酸素リッチガスを吸着塔（Ｂ）入口端部へ並流方向送入し、吸着塔（Ａ）を減圧しつつ、吸着塔（Ｂ）の圧力を中間圧Ｐ_M1→中間圧Ｐ_M2（中間圧（２））へ昇圧する。さらに吸着塔（Ｂ）と吸着塔（Ｃ）とを並流接続することにより吸着塔（Ａ）→吸着塔（Ｂ）→吸着塔（Ｃ）とガスを流し、吸着塔（Ｃ）をパージする。このとき各塔気相濃度は図３（Ｂ）の工程▲２▼に示したように次のごとくなり
吸着塔（Ａ）［２−２−３］→吸着塔（Ｂ）［３−４−３］→吸着塔（Ｃ）［３−２−１］
各塔接続部で酸素濃度の段差がおきないよう、塔間流れを制御する。
【００５３】
工程▲３▼では中間圧Ｐ_M2から操作の最低圧Ｐ_L 迄減圧する。減圧放出ガスは大気へ放出するか、粗窒素として回収する。またはポンプ（１０）を介して、減圧流出ガス中の有効成分を、図５中に点線で示した経路を通じて、同一システム内の他塔へリサイクル回収してもよい。この際、製品として酸素を目的とする場合は主として減圧初期と後期の流出分を回収し、窒素を目的とする場合は、減圧中間期の流出分をリサイクル回収する。
工程▲４▼では吸着塔（Ｂ）出口端の酸素リッチガスが吸着塔（Ｂ）→吸着塔（Ｃ）→吸着塔（Ａ）と並流方向に流れ、吸着塔（Ａ）内残留窒素をパージする。このときの各塔気相濃度は図３（Ｂ）の工程▲４▼に示したように次のごとくなり
吸着塔（Ｂ）［２−２−３］→吸着塔（Ｃ）［３−４−３］→吸着塔（Ａ）［３−２−１］
各塔接続部で酸素濃度の段差が生じないよう、塔間ガス流れを制御する。
【００５４】
工程▲５▼では吸着塔（Ｃ）からの製品酸素の一部が最低操作圧（Ｐ_L ）下にある吸着塔（Ａ）へリークし、吸着塔（Ａ）内圧力をＰ_L →Ｐ_M1へ再加圧する。
工程▲６▼では、吸着塔（Ｃ）→吸着塔（Ａ）→吸着塔（Ｂ）の接続により、吸着塔（Ａ）は中間圧Ｐ_M1→Ｐ_M2迄昇圧する。同時にまた少しおくれて、吸着塔（Ａ）よりの酸素リッチガスにより、吸着塔（Ｂ）がパージされる。このときの各塔気相濃度は図３（Ｂ）の工程▲６▼に示したように次のごとくなり
吸着塔（Ｃ）［２−２−３］→吸着塔（Ａ）［３−４−３］→吸着塔（Ｂ）［３−２−１］
各塔接続部で酸素濃度の段差が生じないよう塔間流れを制御する。
以上で３塔構成システムにおける分離操作を説明した。
【００５５】
３塔構成システムにおける分離操作は２塔構成システムにおける分離操作に比較して、吸着塔間で著しい酸素濃度の段差が生じない点、ポンプの空運転期間がない点で有利である。
４塔式以上になると３塔構成システムより一層酸素濃度の段差が生じにくいが塔数が増えるとシステムが複雑化し、装置価格の上昇につながる。従って、２〜４塔構成システムが適当である。
【００５６】
本発明の気体のバルク分離方法を前記説明の２塔構成システムと３塔構成システムについて一般化して述べると、（１）２塔間操作は全て並流流れ操作とする、（２）２塔間接続は圧力近似であって、一つの塔の昇圧過程と、他の塔の降圧過程を組合わせて行うこと、（３）２つの塔の接続にあたり、気体濃度の段差がおきないよう、各塔間の流れを制御することなどを特徴とする。
【００５７】
本発明においては常温操作を基準とするので、エンタルピー損失は最小にすることができる。但し、季節間における酸素生産量変動を平滑化するため、原料空気温度を例えば１５〜２５℃の一定温度に保つことは差支えない。また、常温より１０〜１５℃高めの温度にて操作することも差支えない。操作温度を少し高くすることは物質移動速度を早め、多くの場合操作上好ましい影響がある。
本発明における操作圧力範囲は、一般には、ポンプに過大な負荷がかからない大気圧近傍であるが下記の２通りに分類される。
（１）最低圧Ｐ_L が大気圧かそれ以上の場合“加圧法”と称す。この場合は、加圧用ポンプのみでよい。
（２）最低圧Ｐ_L が真空圧である場合“真空法”と称す。この場合は、加圧用と真空用と２種のポンプが必要となる。
【００５８】
本発明における作動圧力範囲（中・小型機対象の場合）の例としては次の例を挙げることができる。
（１）０〜７ｋｇ／ｃｍ² Ｇ（ゲージ圧）、標準的には０〜４．５ｋｇ／ｃｍ² Ｇ（ゲージ圧）
（２）０．１〜４ｋｇ／ｃｍ² abｓ（絶対圧）、標準的には０．２〜３．５ｋｇ／ｃｍ² abs （絶対圧）。
【００５９】
本発明の気体のバルク分離方法の実施に適した吸着分離システム（ハード）例を図４〜図９を用いてさらに詳細に説明する。
図４（Ａ）に示した２塔構成システムや、図５に示した３塔構成システムによる気体分離操作は上記の通りである。
本発明の方法では、各塔から酸素リッチガスと窒素リッチガスが交互にでてくる。この際、次の（１）〜（３）の３つのケースがある。
（１）酸素のみ製品とし、窒素は大気へ放出する場合の吸着分離システム例を図７に示す。
（２）酸素と低純度窒素を製品とする場合の吸着分離システム例を図８に示す。
（３）酸素と高純度窒素を製品とする場合の吸着分離システム例を図９に示す。
窒素を製品とする上記（２）および（３）のケースでは、一般に真空法が好ましい。中、小規模の生産システムでは、一般に前処理装置と分離装置を別置せずに、前処理装置（乾燥塔）を後者の分離装置（吸着分離システム）内に含めて１つのシステムとすることが好ましい。
【００６０】
このような例を図７、図８に示す。この場合一般に循環操作毎に乾燥塔の再生を行う。多くの例は酸素のみを製品とするので、残りの排窒素分を乾燥塔に対して向流方向に流し乾燥剤をパージ再生する。
大型・超大型装置では最高操作圧を高めて（Ｐ_H を高くすると装置がコンパクト化できるメリットがある）、降圧過程の圧力エネルギーを膨張機関または発電機で回収することが望ましい。
実際には、図４（Ｂ）に示すごとく、吸着塔から他の吸着塔へガスを降圧しつつ移送する際、高い圧力から両塔間に設けたＥｘ（圧力エネルギー回収手段）を介して低い圧力へと膨張する。また、減圧最終段のガスの圧力エネルギーを回収するときは、弁１４ａ（１４ｂ）−Ｅｘ−１４ｃのごとく流れる。Ｅｘは膨張機関または発電機で、圧力エネルギーはＥｘにより、機械的エネルギーまたは電気エネルギーとして回収され、システム内に保存され、システムの省エネ化に役立てられる。図４（Ｂ）のＶはバイパス弁を示す。
【００６１】
前処理装置が吸着分離システム内に含まれる例について２つのケースを説明する（空気分離例）。
１）図７は酸素の生産のみを目的とする２塔構成システムの例を示す。
図７に示した吸着分離システムの操作のための“弁シーケンス”を図１３に示す。
図７の各部記号は図４（Ａ）に示したものと同一の動作を示すものは同一の記号とした。図７において、Ｄ_A 、Ｄ_B は乾燥塔（シリカゲル、アルミナゲル、活性アルミナ等の乾燥剤が充填される）、ＡＲは原料空気、Ｏ₂ ：製品酸素、ＷＮは排棄窒素、ＷＡは排棄空気を示す。
図７には乾燥塔操作のため弁１５ａ、１５ｂ、１６ａ、１６ｂ、１７ａ、１７ｂが付加される。また弁１８は図４（Ａ）の弁１５と同一の動作（管路（４）内異常圧力上昇の開放）を行う弁である。
図７による分離操作は基本的には図４（Ａ）、図１０（Ａ）に示す分離操作と同一である。
図７の吸着分離システムにおける各弁の１サイクルにおける開閉操作（弁シーケンス）を図１３に示す。
並流減圧２段▲４▼及びパージ工程▲５▼の不用ガスが、弁１５ａ→Ｄ_A →弁１６ａとＤ_A 内を向流方向に流れ、Ｄ_A 内の乾燥剤に吸着されている水分、炭酸ガス等の脱着を促進し、パージガス（ＷＮ）として大気へ放出される。
パージに必要なガスの量は、操作圧Ｐ_H とＰ_L などに関係するが吸着塔（Ａ）に供給される乾燥空気の５〜３０％である。
【００６２】
２）図８は酸素と粗製（低純度）窒素を目的とする２塔構成システムの例を示す。
図８の吸着分離システムの操作のための“弁シーケンス”例を図１４に示す。
図８の吸着分離システムと図７の吸着分離システムの相違点は、真空ポンプ（１０）がつき、真空ポンプ（１０）の作動の円滑化のため、真空ポンプ（１０）廻りに弁１９、２０、２１がつく点、および弁１４ａ、１４ｂがつく点である。
図８による分離操作は、図４（Ａ）、図１０（Ａ）及び図７、図１３で説明した通り基本的には同じである。
吸着塔（Ａ）について、並流減圧操作を弁１５ａ−Ｄ_A −弁１６ａ→真空ポンプ（１０）→弁２１→大気と通じる再生操作と、その後、真空圧迄引く操作とを分けて実施する。後段のガスは窒素成分に富むのでこれを弁１４ａ−真空ポンプ（１０）−弁２０を介して図示しない窒素貯留槽へ回収する。
【００６３】
本発明の気体のバルク分離方法を実施する好適態様としては次のような態様を挙げることができる。
１．空気を原料として酸素（酸素濃度９０％以上）を製品とする。
２．空気を原料として酸素（酸素濃度９０％以上）および／または窒素（窒素濃度９９％以上）を製品とする。
３．分離のためのシステムは２〜４塔構成とする。
４．吸着分離システムを操作する自動弁は電気力および／または空気圧で作動する、オン−オフ弁とする。
５．小容量機では原料混合ガスの前処理装置と分離装置を一体化したシステムとして構成し、一体化、循環操作を行う。
６．気体分離操作温度は常温近傍（２５±１０℃）とすること。
７．気体分離操作圧力は加圧法にあっては、０〜４．５ｋｇ／ｃｍ² Ｇ、真空法にあっては−０．８〜＋３．５ｋｇ／ｃｍ² とすること（但し、中・小容量機対象）。
８．成分（Ａ）を目的製品とするときは、塔内への原料気体送入において、成分（Ｂ）の吸着帯域前縁が塔の末端に到達する直前で、原料気体送入を停止するのが好ましい。また、成分（Ｂ）を目的製品とするときは、塔末端よりの流出ガス中の成分（Ａ）の濃度が次第に減少し、入口濃度と出口濃度が等しくなる直前で原料気体送入を停止するのが好ましい。
【００６４】
【作用】
１．本発明においては、ＰＳＡロス原因である向流減圧操作を並流減圧操作とし有用成分は原則として全てシステム内に回収したこと、システム内に形成された濃度勾配は各個別操作を通じて、維持することによりエントロピーロスを極小化したこと、システム内で発生する温熱および冷熱エネルギーは、全てシステム内での有効活用をはかりエンタルピーロスを極小化したこと、圧力エネルギーは他の吸着塔もしくは膨張機関などの圧力エネルギー回収手段で回収したことにより、省エネ性が著しく向上した。
２．本発明においては、簡単な構成を用い、かつ安い構成材料（主とて鉄と吸着剤）を用い、オン−オフ弁とパルス流制御法（ＰＦ）の採用による高負荷運転により、吸着剤生産性が向上し、コンパクト化が達成されたことにより、省資材性が著しく向上した。
３．省エネ性および省資材性の向上をひっくるめた総合効率が、従来の深冷法や従来のＰＳＡに比して著しく改善され、例えば原料空気から大量、安価な酸素、窒素の供給が可能になった。
４．本発明の方法により、深冷法では達成できない、小容量機のための超コンパクトユニットも可能となった。
５．本発明の方法により、従来のＰＳＡでは著しく困難な酸素、窒素の併産が可能となった。
【００６５】
【実施例】
次に実施例により本発明をさらに詳細に説明するが、本発明の主旨を逸脱しない限り実施例に限定されるものでない。
（実施例１）
本発明の気体のバルク分離方法を、図４（Ａ）に示す２塔構成の吸着分離システム（装置）、図２（Ａ）の［吸着塔（Ａ）および吸着塔（Ｂ）内の圧力〜時間］関係を示す圧力シーケンス、および図１０（Ａ）、（Ｂ）に示す弁シーケンスを用いて空気より酸素（有用ガス）と窒素（不用ガス）を分離する例により説明する。
吸着塔（Ａ）、吸着塔（Ｂ）にはそれぞれ、不用ガスを選択的に吸着する吸着剤ａ、ｂを収納している。吸着塔（Ａ）、吸着塔（Ｂ）はそれぞれ、同一仕様のものである。
【００６６】
図４（Ａ）の下方側から混合気体（乾燥空気）（ＤＡ）を送入し、不用気体（窒素）を吸着させ上方側に送出する。
ポンプ（１）は、原料空気（ＡＲ）を吸引、加圧して管路（２）に送出し、前処理装置（３）にて、空気中の水分、炭酸ガス、微量不純成分等を除去し、加圧乾燥空気（ＤＡ）として管路（４）に送出し、管路（５ａ）、管路（５ｂ）を経て吸着塔（Ａ）、吸着塔（Ｂ）の下方の入口端部から送入する。
吸着塔（Ａ）、吸着塔（Ｂ）の上方側（出口端部）から得られる有用気体（酸素）は管路（６ａ）、管路（６ｂ）から管路（７）を経て製品貯槽（記載せず）に貯留される。
管路（６ａ）、管路（６ｂ）には有用気体（酸素）と不用気体（窒素）が一定時間間隔をおいて交互に送出される。管路（８）は不用気体を放出するための経路である。なお、管路（８）に真空ポンプ（１０）を設けて、不用気体の脱着を促進してもよい。
各開閉弁、１１ａ、１１ｂ、１２ａ、１２ｂ、１３ａ、１３ｂ、１４ａ、１４ｂはそれぞれが配置された管路の気体の通過を開閉するための弁であって、制御部（図示せず）によって所要の工程を成し遂げるよう開閉動作するものである。
【００６７】
・開閉弁１１ａ、１１ｂは上記の送入操作に寄与し、
・開閉弁１２ａ、１２ｂは所要気体（酸素）の採取操作に寄与し、
・開閉弁１３ａ、１３ｂは吸着塔（Ａ）と吸着塔（Ｂ）、または吸着塔（Ｂ）と吸着塔（Ａ）の並流接続操作のための弁で、「均圧操作」と「パージ操作」に寄与する。
・開閉弁１４ａ、１４ｂは不用気体（窒素）の大気放出に寄与する。
・開閉弁（１５）は上記各弁切換操作時における管路（４）の過度的圧力上昇の緩和ないし、開放に寄与する。
・圧力計（Ｐ_A ）、（Ｐ_B ）はそれぞれ吸着塔（Ａ）、吸着塔（Ｂ）の内部の圧力を監視する。
【００６８】
本実施例１では各開閉弁は１サイクルの工程中、弁シーケンスでみると図１０（Ａ）、（Ｂ）のように制御しており、また圧力計（Ｐ_A ）、（Ｐ_B ）でみた圧力変化は図２（Ａ）に示したようになっている。
図１０（Ａ）、（Ｂ）において各開閉弁はハッチングを施した期間だけ開通し、他の期間は停止している。
図２（Ａ）の圧力変化は模型的線図を示したもので、実際には各開閉弁の開閉による各管路内や各吸着塔内の過渡的な変動を伴った変形曲線になる。
【００６９】
１サイクル工程における各操作の順序を説明する。
基本的には各吸着塔（Ａ）、吸着塔（Ｂ）の各圧力変化を１サイクル期間（Ｔ秒）の例えば、Ｔ＝６０秒の１／２、即ち３０秒の位相差による２相の変化曲線をもって、運転操作しているものであり、具体的には、吸着塔（Ａ）内の圧力変化は図２（Ａ）の上部の折れ線で示す変化をもった第１相の圧力変化を行うように、吸着塔（Ｂ）の圧力変化は図２（Ａ）の下部の折れ線で示す変化をもった第２相の圧力変化を行うように運転操作している。
また各圧力変化は最高圧Ｐ_H と最低圧Ｐ_L と、これらの間をほぼ２等分した中間の圧力Ｐ_M の３つの圧力点を経移するように動作している。
【００７０】
そしてまず、動作を開始すると、数サイクルの間は各吸着塔（Ａ）、吸着塔（Ｂ）内の各圧力は種々の過渡的経過をたどるが、やがて、図２（Ａ）の１サイクルの開始点（Ｔ_S ）において吸着塔（Ａ）の圧力は上昇途中でＰ_M に、吸着塔（Ｂ）の圧力は下降途中でＰ_M もしくはその近傍にある。
始点Ｔ_S からの動作を、吸着塔（Ａ）に対する操作、つまり図２（Ａ）の上部に示す圧力変化を主体にして、以下工程順に説明する。
【００７１】
工程▲１▼ 原料加圧操作 ０（＝Ｔ_S ）〜２５秒
開閉弁１１ａを始点Ｔ_S より２５秒間、開放する。
乾燥空気つまり原料気体を吸着塔（Ａ）に加圧送入する操作を行い、吸着塔（Ａ）の圧力を中間圧Ｐ_M から最高操作圧Ｐ_H に移行し、不用気体（窒素）を吸着剤（ａ）で吸着して、有用気体（酸素）を吸着塔（Ａ）の上方側（出口端部）に送出する。また、これと同時に開閉弁１４ｂを２０秒開通して吸着塔（Ｂ）の圧力を管路（８）に排出しうる状態にすることにより、吸着塔（Ｂ）の圧力を中間圧Ｐ_M から最低操作圧Ｐ_L に移行する。この際、真空ポンプ（１０）にて吸引し、最低操作圧Ｐ_L を大気圧以下にすることもできる。
なお本操作期間中においても、始点（Ｔ_S ）から、１５秒後、開閉弁（１３ａ）を５秒間開通して、吸着塔（Ａ）出口端部の酸素リッチガスを最低操作圧Ｐ_L にある吸着塔（Ｂ）に対して、その入口端部から並流方向に流し、吸着塔（Ｂ）内のパージを行う。この操作により吸着塔（Ｂ）内残留不用ガス（窒素）の脱着が促進され、弁（１４ｂ）、管路（８）を経て大気へ放出される。
なおパージ操作終了後も開閉弁１３ａを短時間開放しておき、吸着塔（Ｂ）内圧力を大気圧より高めに保持する［図１０（Ａ）、（Ｂ）の５ａで示す］。
【００７２】
工程▲２▼ 製品取出操作（２０〜２５秒）
工程▲１▼の操作により、吸着塔（Ａ）の圧力が上昇し、最高操作圧近傍に達したら、開閉弁（１２ａ）を開通し、有用成分（酸素）の採取を行う。
即ち、開始時点（Ｔ_S ）から２０秒後、開閉弁（１２ａ）を５秒間開通し、吸着塔（Ａ）出口端部から有用成分（酸素）を取出す。
【００７３】
工程▲３▼ 並流減圧（１）操作（２５〜３０秒（Ｔ_M ））
始点Ｔ_S から２５秒経過したら、開閉弁１１ａを閉止し、弁１３ａを開放、吸着塔（Ａ）と吸着塔（Ｂ）を並流接続する。この操作により吸着塔（Ａ）の圧力は最高操作圧（Ｐ_H ）から中間圧（Ｐ_M ）へ降下し、吸着塔（Ｂ）の圧力は最低操作圧（Ｐ_L ）から中間圧（Ｐ_M ）迄上昇する。
即ち、吸着塔（Ａ）と吸着塔（Ｂ）の圧力が平衡化することで吸着塔（Ａ）→吸着塔（Ｂ）のガスの移行が停止する（均圧という）。
なお、均圧操作期間は開閉弁（１５）を５秒間開放し、管路（４）内の圧力の異常上昇回避する。
【００７４】
工程▲４▼ 並流減圧（２）操作（３０（Ｔ_M ）−４５秒）
始点（Ｔ_S ）から３０秒で、中間点（Ｔ_M ）に達する。Ｔ_S 〜Ｔ_M （３０秒）で工程▲１▼〜▲３▼の操作が終わる。工程▲３▼の操作終了後、弁（１４ａ）を２０秒間開放する。吸着塔（Ａ）の圧力は１５秒後に中間圧（Ｐ_M ）から最低操作圧（Ｐ_L ）へ降下する。
【００７５】
工程▲５▼ パージ操作（４５−５０秒）
工程▲３▼の操作に続いて行われる工程▲４▼の操作は１５秒で停止するが、なお弁（１４ａ）は開放しておく。即ち吸着塔（Ａ）は２０秒間最低操作圧（Ｐ_L ）に保持される。
１サイクルの中間点（Ｔ_M ）より１５秒後、弁（１３ｂ）が５秒間開放され吸着塔（Ｂ）出口端部の酸素リッチガスが吸着塔（Ａ）入口端部から並流方向に導入され、吸着塔（Ａ）内残留不用成分の脱着を促進する。
脱着された不用ガス（排窒素）は弁（１４ａ）を介して管路（８）へ送出され大気に放出される。
【００７６】
工程▲６▼ 再加圧操作［５５−６０秒（Ｔ_E ）］
Ｔ_M で開放された弁１４ａは２０秒後閉止される。
再加圧操作に入る迄の５秒間、弁１３ｂを短時間開放し、内部を正圧（大気圧以上）に保つ［図１１（Ｂ）の５ａで示す］。
Ｔ_M から２５秒後、弁１３ｂを５秒間開放し、再加圧操作が行われる。
この操作の間、吸着塔（Ａ）、吸着塔（Ｂ）の入口〜出口端部の弁は弁１３ｂを除き全て閉止される。弁１３ｂの開放により、吸着塔（Ｂ）出口−吸着塔（Ａ）入口の並流方向に２つの塔が接続され、吸着塔（Ｂ）はＰ_H →Ｐ_M へ降圧し、吸着塔（Ａ）はＰ_L →Ｐ_M まで復圧し、原料送入のための準備が整う。
工程▲６▼操作終了後、再び弁１１ａが開放され、第２周期が始まる。始点Ｔ_S から５５秒−６０秒間、弁１５を開放し、管路（４）の異常圧力上昇を回避する。
【００７７】
以上主として吸着塔（Ａ）に着目して１サイクルにおける各弁の開閉操作を示したが、吸着塔（Ｂ）についても同様な操作が３０秒遅れて行われる。
吸着塔（Ａ）、吸着塔（Ｂ）間の関連操作等は図１０（Ａ）、（Ｂ）に示す通りである。
上記並流減圧（１）操作で並流接続された２つの塔の圧力が平衡する途中で、操作を止め工程▲４▼の操作に入る別の例もある（部分均圧法）。
また、高い圧力の塔への加圧を続行しつつ、または低い圧力の塔の減圧を続行しつつ、２つの塔を接続する別の例もある。
【００７８】
本発明の方法における操作では、総合効率向上のためには、吸着塔に流出入するガス量を迅速精密に制御する必要がある。
一般に、上記の自動開閉弁近傍の管路にオリフィス等の絞り機構、ダイヤフラム調節弁等を付設し、弁の開閉時に該管路を流れるガス流量を連続運転に入る前に調整しておくが、運転開始作業が複雑になったり、自動開閉弁の他に調節手段を付加することは装置の構成を複雑化して装置価格の上昇となったり、流路抵抗によるエネルギー損失につながる恐れがあるので、本発明においては、使用する弁をすべてオン−オフ弁に統一し、前記６つの工程▲１▼〜▲６▼の個別操作のための最適のガス量をオン−オフ弁の精密シーケンスに基づく断続的開閉操作により制御することが好ましい。
【００７９】
図１０（Ａ）において、パージ供与弁１３ａまたは１３ｂを図１０（Ｂ）に示すごとく断続的に開閉する。実施例１においては弁１３ａを１５．０−１５．５、１７．５−１８．０、２０．０−２０．５のごとく開閉操作し、酸素リッチガスを最低操作圧Ｐ_L にある吸着塔（Ｂ）に３つの継続する圧力波として送り込んでいる。そして第１パルスと第２パルスの２波の合計流量が「パージ操作」に必要なガス量になるよう制御している。第３パルス（５ａで示す）は吸着塔内圧力を大気圧より高く保持するための操作である。以上の迅速精密な流量制御法を“パルス流制御法”（Pulsed Flow Control Method）という（ＰＦ）。
【００８０】
このＰＦを図１６および図１７により詳細に説明する。
図１６は本発明の個別操作のための小型シミュレーターの模型図である。
図１６においてＡは吸着塔、Ｖ₁ ，Ｖ₂ はオン−オフ弁、ａは吸着剤、Ｐ₁ ，Ｐ₂ は圧力センサー、Ｒはリザーバー、△Ｐは差圧を示す。
実験操作例を次に示す。
吸着剤ａは活性化後、窒素を充填し、大気圧下もしくは真空圧下におき初期条件をそろえる。初期圧力Ｐ₂ とする。
リザーバ（Ｒ）の中に酸素を入れ、一定圧力（Ｐ₁ ）にしておく（Ｐ₁ ＞Ｐ₂ ）。
オン−オフ弁Ｖ₁ を０．１秒あけ、吸着塔（Ａ）の差圧△Ｐの時間的変化を図形記録する。結果を図１７のＡに示す。
オン−オフ弁Ｖ₁ を０．２、０．３秒・・・等とあけ、吸着塔（Ａ）の△Ｐの時間的変化を図形記録する。０．２秒あけたときの結果を図１７のＢに示す。
【００８１】
図１７のＡとＢの山形、波形を比較する。
図１７のＡに示されているように、△ｔ＝０．１のときは山形頂部がくずれた鋭角状となる。
図１７のＢに示されているように、△ｔ＝０．２のときは山形頂部がほぼ対称的で正弦波に近似する。後者の場合、一定量のガス塊がカラム内を圧力波として円滑に伝播していることを示す。このときのガス塊またはガス波の量は、最小最適なガス量を示す。
図１７のＢの波形図のＨ_B はガス伝播速度に関係し、Ｔ_B は第１波と第２波の待ち時間（ポーズ）を示す。
実施例１の工程▲５▼のパルス操作におけるパルス流制御は、０．５パルス−２．０ポーズ（第１パルス）の操作を第２、第３と３操作行っている。
このときの１パルスの流量は下記式（１）（実験式）で示される。
【００８２】
【数３】

【００８３】
（実施例２）
本発明の気体のバルク分離方法を、図５に示す３塔構成の吸着分離システム（装置）、図３（Ａ）に示す［吸着塔（Ａ）、吸着塔（Ｂ）および吸着塔（Ｃ）内の圧力〜時間］関係を示す圧力シーケンス、および図１１に示す弁シーケンスを用いて空気より酸素と粗窒素を分離製造する例により説明する。
吸着塔（Ａ）、吸着塔（Ｂ）、吸着塔（Ｃ）はそれぞれ、同一仕様のものである。吸着塔（Ａ）、吸着塔（Ｂ）および吸着塔（Ｃ）の内部には窒素ガスを選択的に吸着する吸着剤（ＭＳ−５Ａ）がカラム状に充填されている。
図５の記号の中、実施例１（図４（Ａ））で説明したのと同一記号は同様の機能を示す。ＤＡは加圧乾燥空気を示す。
・開閉弁２１ａ、２１ｂ、２１ｃは加圧乾燥空気の送入操作に寄与し、
・開閉弁２２ａ、２２ｂ、２２ｃは製品酸素の採取操作に寄与し、
・開閉弁２３ａ、２３ｂ、２３ｃは２塔間の並流接続操作に寄与し、
・開閉弁２４ａ、２４ｂ、２４ｃは粗製窒素の採取操作に寄与する。
・開閉弁２６ａ、２６ｂ、２６ｃは有効成分の回収操作に寄与する。
・管路９ａ、９ｂ、９ｃは２塔間を並流接続さすための管路である。
・Ｐ_A 、Ｐ_B 、Ｐ_C はそれぞれ吸着塔（Ａ）、吸着塔（Ｂ）、吸着塔（Ｃ）の内部の圧力を監視する圧力計である。
【００８４】
各開閉弁は１サイクルの工程中、弁シーケンスでみると図１１のように制御しており、また圧力計Ｐ_A 、Ｐ_B 、Ｐ_C でみた圧力変化は図３（Ａ）に示したようにしてある。図１１において、各開閉弁はハッチングを施した期間だけ開通し、他の期間は停止している。図１１において、ハッチング部内の数字は吸着塔（Ａ）に着目した工程▲１▼〜▲６▼順を示す。
図３（Ａ）の圧力変化は模型的線図を示したもので、実際には各開閉弁の開閉による各管路や、各吸着塔内の過渡的変動を伴った変形曲線になる。
１サイクル工程における各操作順に従って説明する。
始点Ｔ_S からの動作を吸着塔（Ａ）に対する操作、即ち図３（Ａ）の上部に示す圧力変化を主体にして説明する。
【００８５】
工程▲１▼ 原料加圧 ０（＝Ｔ_S ）〜２０秒
乾燥空気を吸着塔（Ａ）に加圧送入し、吸着塔（Ａ）内の圧力（Ｐ_A にて示す）を中間圧Ｐ_M2から最高操作圧Ｐ_H に迄上げる。空気中の窒素を吸着剤カラムで吸着し、酸素を吸着塔（Ａ）の出口端部に送出する。またこの操作期間中で、吸着塔（Ａ）内圧力がＰ_H 近傍に達したら酸素送出弁２２ａを５秒間あけて所定量の酸素を管路（７）へ送出する。管路（７）には製品酸素の貯留槽（記載せず）が接続されており、そこから消費端へ送られる。
また、弁２３ａを１．０秒間開放し、最低操作圧Ｐ_L 下にある吸着塔（Ｂ）の再加圧（１）を行う（図１１中５ａで示す）。
【００８６】
工程▲２▼ 並流減圧（１） １０〜２０秒
吸着塔（Ａ）に対して乾燥空気の送入を続行しつつ、弁２３ａを１０秒間開放し、吸着塔（Ａ）と吸着塔（Ｂ）を並流接続し、吸着塔（Ａ）出口端部の酸素リッチガスを吸着塔（Ｂ）に回収する、少しおくれて弁２３ｂが開放される、吸着塔（Ｂ）を中間圧Ｐ_M1からＰ_M2迄、再加圧を行う。同時に、吸着塔（Ａ）は最高操作圧Ｐ_H からＰ_M2迄降圧する。
【００８７】
工程▲３▼ 並流減圧（２） ２０〜３０秒
弁２４ａを１０秒間開放する。吸着塔（Ａ）に残留する窒素リッチガスは、管路（８）へ送出される。そこから窒素貯留槽（記載せず）へ送られる。酸素生産が目的のときは管路（８）を経て大気中へ放出される。吸着塔（Ａ）内圧力は最低操作圧Ｐ_L に降下する。減圧流出ガス中の酸素分を回収する場合は、弁２０ｂ−ポンプ（１０）−弁２６ｂと点線で示す経路を通じて吸着塔（Ｂ）へリサイクル回収する。
【００８８】
工程▲４▼パージ ３０〜４０秒
この操作期間中、吸着塔（Ａ）は最低操作圧Ｐ_L 下にある。
図３（Ａ）に示すごとく、パージ用の酸素リッチガスが吸着塔（Ｂ）→吸着塔（Ｃ）→吸着塔（Ａ）と並流方向に流れ、吸着塔（Ａ）内に残留する窒素リッチガスを吸着塔（Ａ）へ出口端部へ押し出し、弁２４ａを介して管路（８）へ送出される。
この操作で重要なことは、２塔間接続部で濃度勾配の段差がおきないよう、各塔内の圧力変化が圧力シーケンス図［図３（Ａ）］に沿うよう流量調節しなければならないことである。
【００８９】
工程5) 再加圧（１） ４１〜４２．０秒
弁２３ｃを１．０秒間開放し、吸着塔（Ａ）の再加圧（１）を行う。図１１中の工程5)で示す。吸着塔（Ａ）内の圧力は約０．２５ｋｇ／ｃｍ² Ｇへ上昇する。
【００９０】
工程▲６▼ 再加圧（２） ５０．０〜６０．０秒
弁２３ｃを１０秒間開放し、吸着塔（Ｃ）と吸着塔（Ａ）を並流接続し、吸着塔（Ｃ）を減圧しつつ、吸着塔（Ａ）の再加圧（２）を行う。少しおくれて吸着塔（Ａ）と吸着塔（Ｂ）を並流接続し、吸着塔（Ａ）→吸着塔（Ｂ）へパージガスを供給する。吸着塔（Ａ）内圧力は０．２５ｋｇ／ｃｍ² →２．５ｋｇ／ｃｍ² 迄昇圧する。
【００９１】
以上、主として吸着塔（Ａ）に着目して１サイクル時間６０秒における各弁の開閉操作を示したが、吸着塔（Ｂ）、吸着塔（Ｃ）についても各々６０／３＝２０秒遅れて同様な操作が行われる。吸着塔（Ａ）、吸着塔（Ｂ）、吸着塔（Ｃ）間の関連操作等は図１１に示す通りである。
【００９２】
３塔構成以上のシステムの動作においては、３つの塔が並流接続してガスが流れるので、流量調節は大切である。２塔式に常用される減圧操作は２つの塔を並流接続して圧力が平衡化したら操作を停止する。このときには、ガスの移送量（全量）の制御については、考慮する必要がない。但し、圧力の降下（上昇）が圧力シーケンス図上で直線的で、かつ所定時間で丁度終わるようにするための流速の調節は必要である。
３塔構成のシステムの場合は、移動さすガスの量（全量）および移動速度（圧力シーケンス間に沿うように）の双方が最適値であるよう、配慮しなければならない。
【００９３】
４塔構成のシステムと分離操作も３塔構成のシステムの場合と同様の考え方で実行できる。
図６に示す４塔構成の吸着分離システム（装置）および図１２に示す弁シーケンスを用いて空気より酸素と粗窒素を分離製造する例により説明する。４塔構成のシステムの場合も３塔構成のシステムの場合と同様▲１▼〜▲６▼の６工程を行う。４塔構成のシステムの場合の▲１▼〜▲６▼の６工程と３塔構成のシステムの場合の▲１▼〜▲６▼の６工程を比較した結果を表３に示す。
【００９４】
【表３】

【００９５】
“並流減圧と再加圧が３段階に分かれる”ところが３塔構成のシステムと異なる。但し考え方の基本は同一である。
【００９６】
（実施例３）
図９に示す２塔構成の吸着分離システム（装置）および図１５に示す弁シーケンスを用いて空気より酸素と高純度窒素を製造する例を説明する。
吸着塔：内径５３ｍ／ｍ×長さ２３０ｍ／ｍ×２塔
吸着剤：ＭＳ−５Ａ（吸着塔（Ａ）への充填量；２９８ｇ、吸着塔（Ｂ）への充填量；３０５ｇ）
図９に示す２塔構成の吸着分離システム（装置）と図４に示す２塔構成の基本吸着分離システムとは、図９の場合は高純度窒素製造のため、弁と窒素リザーバー（窒素貯留槽）がつく以外は同じであり、記号説明で図４の記号と重複する箇所は省く。
ＤＡ：加圧乾燥空気
Ｏ₂ ：製品酸素（純度９３％以上）
ＨＮ₂ ：高純度窒素（純度９９．５％以上）
ＷＡ：排気空気
Ｒ_O ：製品酸素貯留槽
Ｒ_N ：製品窒素貯留槽
１０：真空ポンプ
各弁はすべて開閉弁である。
実施例３では各弁は１サイクル工程中、弁シーケンスでみると図１５のように制御しており、ハッチングを施した期間だけ開通している。
ハッチング部の番号は吸着塔（Ａ）に関しての工程順を示す。
【００９７】
１サイクル操作は次の▲１▼〜▲８▼の８つの工程から成る。
実施例１で示した２塔構成の基本シーケンスとの相違点は、基本シーケンスの工程▲３▼並流減圧（２）と工程▲４▼パージ操作の間に、高純度窒素製造のための「窒素置換操作」と「窒素回収操作」が入るのみである。
説明の重複をさけ以下に吸着塔（Ａ）に着目して本例の分離操作を説明する。

【００９８】
工程▲１▼、▲２▼、▲３▼、▲４▼、▲７▼、▲８▼については実施例１で説明した通りである。工程▲５▼、▲６▼について説明する。
工程▲５▼ 窒素置換 ３０．０〜３７．５秒
１サイクルの開始時点Ｔ_S から３０．０秒後、弁２０ａ、２０ｂ、１７ａ、１８ａの４つの弁を開け、窒素貯留槽Ｒ_N 内の高純度窒素を吸着塔（Ａ）入口端から並流方向に送入し、吸着塔（Ａ）内気相部に残留する酸素分を出口端部へ押しやり、弁１８ａを経て、空気中へ放出される。この操作は高純度窒素が吸着塔（Ａ）出口端へ到達した時点で停止する。
【００９９】
工程▲６▼ 窒素回収 ３７．５〜５０．０秒
工程▲５▼の操作が終了したら、弁１４ａ、２０ｃを開放し、吸着塔（Ａ）を真空ポンプ（１０）により真空吸引する。この操作により吸着塔（Ａ）内気相と吸着層に存在する窒素は吸引され窒素貯留槽（Ｒ_N ）へ送られる。そこから加圧され高純度窒素（ＨＮ₂ ）として、消費端に送られる。なお、窒素貯留槽は可撓性構造であることが好ましい。
工程▲５▼、▲６▼の操作終了後の真空下の吸着塔（Ａ）に対して、弁１３ｂの断続的開放操作（ＰＦ制御法）により、酸素がパージ供給される。
本例では、０．５秒のパルスを２パルス操作している。
以上の１サイクル操作における、吸着塔（Ａ）、吸着塔（Ｂ）へのガスの流出入及びポンプの作動状況は図１５に示した弁シーケンスで明らかである。
かくして３０秒毎に吸着塔（Ａ）、吸着塔（Ｂ）から交互に９０％以上の酸素と９９．５％以上の窒素が生産された。
【０１００】
実施例３の分離操作は２塔システムのみに限定されるものでなく、３塔構成以上のシステムでも実施することができる。３塔以上のシステムでは、ポンプ（１）、真空ポンプ（１０）の空転期間をなくすことが容易となる。
【０１０１】
上記の実施例１〜実施例３、図１０〜図１５に示す弁シーケンスは代表例を示すものであり、他にも種々の変形態様での実施が可能であるが、本発明の主旨を逸脱しない限り、全て本発明の範囲に属するものである。
【０１０２】
【発明の効果】
本発明の気体のバルク分離方法は、構成が簡単な吸着分離システム（装置）を用い、安価な材料を使用を用い、吸着分離システム（装置）がコンパクトであるので、従来の深冷法に比し、装置価格が著しく安くなり、構成材料は環境に無害な鉄と石（吸着剤）であるので、廃棄処分費を考慮すると格段に経済的である。本発明の気体のバルク分離方法は、気体が一定周期の圧力変動しつつ、一定方向に流れ、この流れ過程を通じ、濃度勾配を一定に維持すること（等エントロピー過程）、吸着分離システム内で発生する吸着熱及び脱着熱（冷熱）をシステム内で有効活用すること（等エンタルピー過程）、圧力エネルギーを他の吸着塔の昇圧に使用するか、または膨張機関などにより機械的および／または電気エネルギーとして回収することにより熱力学的省エネプロセスとなる。
以上のように本発明の気体のバルク分離方法は、省エネ、省資材的プロセスであるので、総合効率が著しく向上し、原料混合ガスから大量、安価な酸素や窒素あるいは水素等を分離して供給することが可能になった。
【０１０３】
近年エネルギー、環境問題の高まりとともに、酸素高炉法、溶融還元製鉄法、石炭ガス化複合発電、高温燃料電池等の新製鉄法、新発電システムの大規模開発プロジェクトが進行中であるが、これら次世代型技術は大量の酸素・窒素等のガスを消費する。
本発明の気体のバルク分離方法は、上記次世代型技術のための大量・安価なガス供給手段として、その経済的成立に大きく寄与するものである。
【０１０４】
また、本発明の気体のバルク分離方法は、自動車に搭載可能な小型コンパクトなガス分離器を可能にした。
即ち、ディーゼル車に搭載して、パティキュレートバーンアウトのための酸素炎として、あるいは燃料電池電気自動車の酸素、窒素源、水素分離器等として電池のコンパクト化、省エネ化に役立つ効果も期待される。
【０１０５】
本発明の気体のバルク分離方法は、空気より酸素と窒素の分離のみならず、他の混合ガス（例えばＨ₂ −ＣＯ₂ 、Ｈ₂ −Ｎ₂ 、Ｎ₂ −ＣＯ等）の分離にも適用可能である。
以上により本発明の気体のバルク分離方法は産業上の利用価値が甚だ大きい。
【図面の簡単な説明】
【図１】 本発明の方法を実施するための基本システムを示す説明図である。
【図２】 （Ａ）は本発明に係わる２塔構成システムの各塔の圧力シーケンスを示し、（Ｂ）は各吸着塔内の気相濃度分布の変化を示す説明図である。
【図３】 （Ａ）は本発明に係わる３塔構成システムの各塔の圧力シーケンスを示し、（Ｂ）は各吸着塔内の気相濃度分布の変化を示す説明図である。
【図４】 （Ａ）は、本発明に係わる基本システム例（２塔構成）を示す説明図であり、（Ｂ）は、圧力エネルギー回収手段（ＥＸ）を用いて降圧過程の圧力エネルギーを膨張機関または発電機で回収する場合の（Ａ）に示した基本システム例（２塔構成）の変形態様を示す説明図である。
【図５】 本発明に係わる３塔構成の基本システム例を示す説明図である。
【図６】 本発明に係わる４塔構成の基本システム例を示す説明図である。
【図７】 本発明に係わる２塔構成で乾燥塔を備えた基本システム例を示す説明図である。
【図８】 本発明に係わる２塔構成で乾燥塔および真空ポンプを備えた基本システム例を示す説明図である。
【図９】 本発明に係わる２塔構成で、真空ポンプ、製品酸素貯留槽および製品窒素貯留槽を備えた基本システム例を示す説明図である。
【図１０】 図４に示した基本システム操作のための弁シーケンス例を示す説明図である。
【図１１】 図５に示した基本システム操作のための弁シーケンス例を示す説明図である。
【図１２】 図６に示した基本システム操作のための弁シーケンス例を示す説明図である。
【図１３】 図７に示した基本システム操作のための弁シーケンス例を示す説明図である。
【図１４】 図８に示した基本システム操作のための弁シーケンス例を示す説明図である。
【図１５】 図９に示した基本システム操作のための弁シーケンス例を示す説明図である。
【図１６】 “パルス流制御法”（ＰＦ）による自動弁のパルス的開閉操作試験を行うための小型シミュレーターの模型図である。
【図１７】 図１６に示した小型シミュレーターを用いて試験した時の吸着塔内差圧（△Ｐ）の時間的変化を示すグラフである。
【符号の説明】
ＤＡ 乾燥空気
Ａ、Ｂ、Ｃ、Ｄ 吸着塔
ａ、ｂ 吸着剤
ＡＲ 原料空気（加圧乾燥空気）
Ｄ_A 、Ｄ_B 乾燥塔
Ｅｘ 圧力エネルギー回収手段
Ｖ バイパス弁
Ｏ₂ 製品酸素
Ｎ₂ 製品窒素
ＨＮ₂ 高純度窒素
ＷＡ 排気空気
ＷＮ 排気窒素
１ ポンプ
２、４、５ａ、５ｂ、５ｃ、６、６ａ、６ｂ、６ｃ、７、７ａ、７ｂ、８、９ａ、９ｂ、９ｃ 管路
３ 前処理装置
５ 分離装置（またはシステム）
２７、２８ 製品取出自動弁
１０ 真空ポプ
１１ａ〜１７ａ、１１ｂ〜１７ｂ、１４ｃ、１５、１８、１８ａ、１８ｂ、２０ａ〜２０ｅ、１９〜２１、２１ａ〜２５ａ、２１ｂ〜２５ｂ、２１ｃ〜２５ｃ、２６ａ〜２６ｄ、３１ａ〜３４ａ、３１ｂ〜３４ｂ、３１ｃ〜３４ｃ、３１ｄ〜３４ｄ、３５ａ、３５ｂ、３６ａ、３６ｂ 自動（開閉）弁[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a gas bulk separation method by parametric gas chromatography, and more specifically, a raw material containing a hardly adsorbable component (A) and an easily adsorbable component (B), for example, separating and producing oxygen and nitrogen from air. The mixed gas was passed from the inlet end to the outlet end of the adsorbent column, and the hard-adsorbing component (A) and the easy-adsorbing component (B) were separated from each other at regular intervals from the outlet end, and alternately come out. The present invention relates to a gas bulk separation method capable of separating and producing a hardly adsorbable component (A) and an easily adsorbable component (B) with low power consumption and high overall efficiency.
[0002]
[Prior art]
Currently, industrial production of oxygen and nitrogen is mainly performed by air liquefaction separation method (abbreviated as deep cooling method). By means such as pipeline or liquid acid transport, oxygen is mainly used for steel and metallurgy, and nitrogen is used for LSI manufacturing. It is supplied to and used by the electronics industry as atmospheric gas.
Further, in some small and medium-sized applications, oxygen and nitrogen are separated from air using a well-known on-site pressure swing adsorption method (hereinafter referred to as PSA) and supplied by pipeline.
[0003]
The deep cooling method is the only method that can produce a large amount of high-purity oxygen and high-purity nitrogen at the same time. However, the apparatus configuration is complicated and high-grade materials are used. This deep cooling method was invented around 1900, and by 1955, the basics of industrial equipment had reached the level of completion. Even now, the efficiency of component parts and machinery is improved, the price is reduced, Although partial improvements such as improvement of the rectification column have been continued, it is not possible to expect a fundamental increase in efficiency.
[0004]
PSA, on the other hand, is a method of producing 90-95% oxygen by simple equipment and room temperature operation, and is used in small and medium-scale applications where the cryogenic method is not economically attractive, such as electric furnaces, wastewater treatment, It is used as pulp bleaching and ozonizer addition equipment.
This PSA is a technology that was invented around 1957. From the beginning until recently, efforts have been made to improve energy saving, and numerous patents have been filed. In particular, as a recent trend, adsorbent productivity [liter (oxygen) / kg- (adsorbent) (H)] (which is an index for saving materials in PSA) has been greatly improved.
Recently, a new PSA with a higher overall efficiency has been proposed by adopting LiX type zeolite, which has better adsorption performance than conventional adsorbent MS-5A zeolite and / or speeding up the process (for example, JP-A-2-68111, JP-A-7-185247, JP-A-3-52615, JP-A-6-55027, etc.).
[0005]
In recent years, with the increasing energy and environmental problems, various development projects are underway with the aim of industrialization of new power generation systems and new iron manufacturing methods that pursue energy and material savings. Examples of these development projects include, for example, coal gasification combined power generation, high temperature fuel cells, oxygen blast furnace method, smelting reduction iron making method, and a large amount of oxygen and nitrogen is consumed in a practical system.
Therefore, there is a great expectation for an oxygen / nitrogen production apparatus and an oxygen / nitrogen production method with high overall efficiency that combine energy saving and material saving (or simple configuration, low cost equipment, etc.).
[0006]
[Problems to be solved by the invention]
The evaluation scale of the adsorption separation system (apparatus) is described.
The smaller the two index values (1) and (2) below, the better the adsorption separation system. The same applies to other mixed gases, but oxygen production will be described as an example.
(1) Oxygen intensity = KWH / m ^Three (NTP) (oxygen) → energy saving scale
(2) Equipment price per oxygen production capacity
Equipment price / m ^Three (NTP) (oxygen) / H → Material saving scale
After all, the oxygen production cost including the above (1) and (2) [yen / m ^Three The smaller the (oxygen)], the better. When the above (1) and (2) are both small, it is defined that the total efficiency is high and used below.
[0007]
The deep cooling method that represents the current “air separation method” is mainly an ultra-low temperature process near −200 ° C., and energy saving has been pursued for many years, and improvements in equipment parts and machinery have almost reached their limits. Therefore, it is difficult to expect a significant improvement in overall efficiency.
The other PSA has improved yield (energy saving) in the early stages of development, recently "adsorbent productivity" [liter (90% oxygen) / kg (adsorbent) H] (material saving) [1 kg of adsorbent for 1 hour. The larger the value of how many liters can be produced, the more compact the production (material saving). Used exclusively as a material-saving measure of PSA. ] Was pursued, and energy saving and material saving progressed. Although PSA has almost reached completion in nearly 40 years of development, it still has the following issues.
(1) The purity of oxygen is 99.5% or higher in the cryogenic method, whereas PSA is as low as 90 to 95%. 5KWH / m ^Three (NTP) oxygen], there is room for improvement, and this value is 0.069 (KWH / m) of the semipermeable membrane work (theoretical value) of complete separation of air ^Three Compared to (oxygen), the value is considerably larger, and the oxygen intensity must be made smaller.
(2) The initial PSA adsorbent productivity is about 10 to 15 [liter (90% oxygen) / kg- (adsorbent) (H)], and the latest PSA adsorbent productivity is about 40 to It should be about 60 [liter (90% oxygen) / kg- (adsorbent) (H)], and the adsorbent productivity value should be further increased.
(3) Oxygen-nitrogen can be co-produced.
The current PSA is a single-capacity machine that produces only oxygen or nitrogen. Although current PSA can co-produce oxygen-nitrogen, the system becomes complicated and the advantages of PSA are impaired.
[0008]
The object of the present invention is to reduce the energy requirement, reduce the oxygen intensity, improve the adsorbent productivity, and improve the overall efficiency by a simple structure, for example, from the raw air at low cost. It is to provide a method for bulk separation of gases so that nitrogen and nitrogen can be produced together.
[0009]
[Means for Solving the Problems]
The present inventor pursued the miniaturization limit of small oxygen-PSA, and as a result of many experiments and evaluations, found "pulse flow control type PSA" (abbreviated as PF-PSA) and filed 16 patent applications first. It was. That is, in order to increase the oxygen production amount with a constant adsorbent amount, it is necessary to change to a larger pump and increase the air load on the adsorbent. As a result, the fluctuation of the gas flow entering and exiting the adsorption tower becomes severe. Therefore, the PF-PSA converts the gas flow into a pressure wave by opening and closing the high-speed on-off valve intermittently based on a certain sequence, thereby enabling rapid and precise control of the gas flow entering and exiting the adsorption tower. Succeeded and achieved an adsorbent productivity of 400 [liter (90% oxygen) / kg- (adsorbent) (H)] (the world's highest value) with the simplest system with two towers.
[0010]
This PF-PSA control method was applied to large PSA, and high adsorbent productivity was achieved even in large machines. However, in order to further improve the yield compared to regular PSA, experiments and evaluations were repeated. Here, unlike the conventional PSA, the present inventors have reached the “new adsorption separation method for all the co-current regions” of the present invention in which all the individual operations constituting the PSA are performed in parallel.
[0011]
The “new adsorptive separation method in the entire co-current region” of the present invention is similar to gas chromatography in that it is a co-current adsorptive separation operation, but does not use a non-adsorbing gas (such as He) as a carrier gas. Normal gas chromatography in that all conditions of the carrier gas (pressure, temperature, composition, flow rate, etc.) vary from moment to moment (parametric, parameter-variable), while all conditions are usually constant. Therefore, the present invention is hereinafter referred to as “parametric gas chromatography” (abbreviated as PGC).
[0012]
The invention of claim 1 of the present invention adsorbs the raw material mixed gas containing the hardly adsorbing component (A) and the easily adsorbing component (B) in a small amount as compared with the component (A) and component (B) therein. At least an adsorption tower packed in a column or layer with an adsorbent capable of selectively adsorbing the component (B) after preliminarily removing moisture, carbon dioxide gas, and other easily condensable gases, which have extremely high properties A gas bulk separation method for obtaining component (A) and / or component (B) from one end (inlet end) to the other end (outlet end) of the adsorption tower of an adsorption separation system comprising two, Each adsorption tower is subjected to the following sequence of steps (1) to (6) in a cyclic manner, and from the other end (exit end), it is alternately turned into products at regular intervals with low power consumption and high overall efficiency. Obtaining component (A) and / or component (B) A bulk separation process of gases by La metric gas chromatography.
(1) The raw material mixed gas is passed to the inlet end of the adsorption tower, the pressure in the tower is increased from the intermediate pressure to the maximum operating pressure, and the component (B) in the raw material mixed gas is selectively adsorbed, And the gas rich in component (A) and / or component (A) is taken out from the other end (outlet end).
(2) While continuing the raw material supply, the gas rich in component (A) and / or component (A) is taken out from the outlet end near the maximum operating pressure.
{Circle around (3)} The raw material supply is stopped, the adsorption tower is depressurized in the parallel flow direction, and the reduced pressure gas does not pass to the inlet end of another adsorption tower that is in the same circulation operation and whose pressure rises.
(4) Continue depressurization and set the atmospheric pressure or the atmospheric pressure to a vacuum pressure. The gas released and / or sucked from this adsorption tower is released to the atmosphere, recovered to another adsorption tower, or the component ( B) Take the product out of the system.
(5) A gas rich in component (A) and / or component (A) is introduced as a purge gas in the co-current direction from the other adsorption towers in the same circulation operation to the adsorption tower under the lowest operating pressure. The component (B) is replaced with the component (A), and the gas rich in the component (B) and / or the component (B) is taken out from the outlet end of the adsorption tower.
(6) After the above operation is completed, the gas from the other adsorption tower whose pressure is approximately the same during the circulation operation and the pressure is decreasing is passed to the inlet end to increase the pressure to the intermediate pressure of the operation.
[0013]
According to a second aspect of the present invention, in the method according to the first aspect, the step (3) is performed while the supply of the raw material mixed gas is continued.
[0014]
The invention according to claim 3 of the present invention is characterized in that, in the method according to claim 1, the pressure reducing operation in step (3) and step (4) and the pressure increasing operation in step (6) are performed stepwise.
[0015]
The invention of claim 4 of the present invention is characterized in that, in the method of claim 1, the raw material mixed gas is air, and the product gas is 90% or more of oxygen and / or 90% or more of nitrogen.
[0016]
According to a fifth aspect of the present invention, in the method according to the first aspect, the adsorbent is a nitrogen-selective adsorptive zeolite-based molecular sieve material.
[0017]
The invention of claim 6 of the present invention is characterized in that, in the method of claim 1, the adsorption separation system comprises two adsorption towers.
[0018]
A seventh aspect of the present invention is the method according to the first aspect, characterized in that the adsorption separation system comprises three or more adsorption towers.
[0019]
The invention according to claim 8 of the present invention is the method according to claim 1, wherein the effluent gas of step (1) is supplied to another adsorption tower as the purge gas of step (5), and component (A) of step (2) is provided. Is a product.
[0020]
According to the ninth aspect of the present invention, in the method according to the first aspect, the effluent gas of step (2) is supplied to another adsorption tower as a purge gas of step (5), and component (A) of step (1) is provided. Is a product.
[0021]
A tenth aspect of the present invention is characterized in that, in the method according to the first aspect, the cocurrent reduced pressure gas in step (4) and / or the component (B) sucked by a pump is used as a product.
[0022]
According to an eleventh aspect of the present invention, in the method according to the first aspect, a pretreatment tower filled with a pretreatment adsorbent selected from silica gel, activated carbon, alumina gel, activated alumina, and zeolite is provided in the adsorption separation system. In the steps (4) and (5), a part of the reduced pressure and / or purge discharge gas is supplied as a regeneration purge gas for the pretreatment tower.
[0023]
The invention according to claim 12 of the present invention is the method according to claim 1, wherein the active ingredient in the gas discharged from the adsorption tower in step (4) and step (5) [the component (if the target product is component (A)] A) When the target product is the component (B), the component (B)] is recycled and recovered to another adsorption tower in the same system via a pump.
[0024]
According to a thirteenth aspect of the present invention, in the method according to the seventh aspect, in the adsorption separation system comprising three or more towers, the individual operation for connecting the two adsorption towers is for a two-adsorption tower having an approximate operating pressure. Using a pressure difference from one adsorption tower to the other adsorption tower, gas flows in the cocurrent direction, the pressure drop of one adsorption tower and the pressure rise of the other adsorption tower, and the adsorption tower under the minimum operating pressure On the other hand, a purge operation is performed.
[0025]
The invention according to claim 14 of the present invention is the method according to claim 1, wherein when the two adsorption towers are connected by an adsorption separation system comprising two or more towers, the gas pressure in the adsorption tower is in the process of increasing the pressure in the adsorption tower. The concentration distribution is such that the component (A) becomes rich toward the outlet end, and the gas phase concentration distribution in the adsorption tower in which the pressure in the adsorption tower is decreasing, the component (B) becomes rich toward the outlet end. The gas transfer amount is controlled so that there is no step between the outlet concentration of one adsorption tower and the inlet concentration of another adsorption tower.
[0026]
According to a fifteenth aspect of the present invention, in the method according to the tenth aspect, the component (B) in the step (4) is once recovered in an intermediate tank, and the component (B) in the intermediate tank ( B) is recirculated to the inlet end of the adsorption tower through a pump to replace the inside of the tower with the component (B). Thereafter, the gas in the adsorption tower and the component (B) in the adsorbent are sucked by the pump. The component (B) is recovered as a high-purity product.
[0027]
According to a sixteenth aspect of the present invention, in the method according to the sixth aspect, in the adsorption separation system having a two-column configuration, the two adsorption towers are connected in the parallel flow direction to perform pressure equalization or partial pressure equalization.
[0028]
According to a seventeenth aspect of the present invention, in the method according to the first aspect, the step (3) and (4) are stepped down through pressure energy recovery means such as an expansion engine, and the pressure energy is supplied to an electric and / or mechanical machine. It is recovered as energy.
[0029]
The invention according to claim 18 of the present invention is the method according to claim 1, wherein in a simulator test for moving gas by connecting two adsorption towers having a pressure difference through an automatic on / off valve. Using the automatic on-off valve opening time (Δti) as a parameter, the time (t) change in differential pressure (ΔP) between the inlet end and outlet end of the adsorption tower on the downstream side is measured and graphed ( Vertical axis: ΔP, horizontal axis: t), when this figure is a sine wave or sine wave approximate wave type, Δti is the pulse time, the value obtained by subtracting Δti from the half-wave width is ΔZi, and the above automatic on -When the amount of gas (Vi) passing through the off valve is determined by the following equation (1)
△ t ₁ (Open)-△ Z ₁ (Closed)-△ t ₂ (Open)-△ Z ₂ Gas necessary and sufficient for the individual operations of steps (1) to (6) described above by the valve opening / closing sequence (valve opening time-time relationship) of (closed) ... -Δti (open)-ΔZi (closed) The movement amount (ΣVi) and the gas movement speed [ΣVi / (Σti + ΣZi)] are controlled.
[0030]
[Expression 2]

[0031]
DETAILED DESCRIPTION OF THE INVENTION
The method of the present invention is similar to a conventional gas chromatography operation in that the raw material mixed gas is passed from one end of the adsorbent column to the other end, and oxygen and nitrogen, for example, alternately come out from the outlet end at regular intervals. Differ in the following points.
(1) A third gas [a gas other than component (A) or component (B)] is not used as a carrier gas. When performing oxygen-nitrogen separation by gas chromatography, non-adsorbing He gas or the like is used.
(2) In the method of the present invention, the gas corresponding to the carrier gas is component (A), component (B) or a mixed gas thereof. Also, it is not supplied at a constant flow rate.
(3) The composition, pressure, temperature, flow rate, etc. of the carrier gas in the method of the present invention shown in (2) above are periodically changed in a constant pattern and are parameter-variable.
In addition, the method of the present invention is a circulation operation that utilizes the adsorption / desorption effect due to pressure fluctuation, and is similar to regular PSA (pressure fluctuation adsorption method), but the gas flow is only in one direction (cocurrent flow) throughout the whole operation. Therefore, it is different from the common use PSA in which two operations of the parallel flow and the counter flow are combined.
[0032]
The process from regular PSA to parametric gas chromatography is briefly described below. An explanation will be given by taking oxygen production from air as an example.
The basic process of regular PSA consists of the following four individual operations. Focusing on one column, (1) feed air pressurization, (2) product oxygen removal, (3) counter-current pressure reduction, (4) purge and return to (1).
There are about 2000 patents for regular PSA, most of which are variations of the above four-step process.
Next, a typical process will be described.
1) After the purging step (4), a part of product oxygen is allowed to flow in the counter-current direction (reflux), and the pressure in the column is restored to the intermediate pressure or higher.
2) Depressurization is performed, for example, in two or three stages of cocurrent flow and one stage of countercurrent, and the cocurrent depressurization gas is collected in another tower and the countercurrent depressurization gas is released to the atmosphere.
3) A pressure equalization operation is performed between steps (2) and (3) and between steps (4) and (1) to depressurize or pressurize the column.
4) Promote the counter-current pressure reduction of (3) above using a pump (referred to as vacuum method). The minimum pressure for operation is vacuum.
[0033]
The main cause of inefficiency (decrease in yield) in the above-mentioned regular PSA is mainly due to the “countercurrent” operation of (3) and (4) above, and the active component oxygen is released out of the system by the “countercurrent” decompression operation. .
In order to reduce this oxygen loss as much as possible, many improvements have been made over the years and many PSA patents have been proposed to date.
[0034]
Therefore, the present inventor applied a part of the method of the pulse flow control method to trace the changes in the amount and purity of the gas in the countercurrent operations (3) and (4) in detail. The counter-current decompression loss in 3) is much larger than the purge loss in (4) above, and when the counter-current decompression is divided into the initial, middle and late steps, the initial loss is large and the purge effect is large. Also, since the purge loss is small, it has been found that this effect should be actively utilized.
[0035]
It is established in the prior art to recover the pressure loss in the system by dividing the pressure reduction into several separate operations, cocurrent and countercurrent, and “multi-stage” to recover the pressure loss. In this case, however, the number of towers is 3 to 4 and the configuration is complicated.
Therefore, in the present invention, all the decompressions are in the co-current direction, and all active components are collected in principle. In order to prevent the purge loss, the “purge” is actively used for regeneration of the adsorption tower. Concentration gradient is kept constant throughout the individual operations, minimizing entropy loss due to mixing, and recovering pressure energy as much as possible, especially in large capacity machines, and the constituent materials are iron and stone (zeolite), By not using high-grade materials (copper, aluminum) such as the deep cooling method, it has excellent energy saving and material saving properties, and oxygen-nitrogen can be produced at the same time. The overall efficiency including all disposal costs is much improved compared to conventional air separation methods (deep cooling method, regular PSA).
[0036]
The method of the present invention will be specifically described with air separation as an example.
FIG. 1 shows a basic system for carrying out the method of the invention.
This basic system is composed of three parts: a pump (1), a pretreatment device (3), a separation device (or system) (5), connection pipes (2, 4, 6), and product take-off valves (27, 28). .
1) The raw material air is pressurized by the pump (1) and sent to the pretreatment device (3) through the pipe line (2).
2) Moisture, carbon dioxide, etc. in the raw material air are removed by the pretreatment device (3) and sent to the pipe (4) as dry air (DA). The pretreatment method may be any of adsorption type, refrigerant type, membrane type, or a combination of these, but select a low cost, energy saving and low product loss so as not to reduce the overall efficiency. It is preferable.
3) Dry air (DA) is sent to the separator (or system) (5). DA is separated into oxygen and nitrogen by this device (5) and is alternately sent to the pipe (6) at regular intervals.
4) Product oxygen (O) by opening and closing the automatic valves (27) and (28) connected to the pipe (6) alternately at regular intervals. ₂ ), Product nitrogen or exhausted nitrogen (N ₂ The product gas is stored in a product storage tank (not shown) connected downstream of each valve and sent from there to the consumption end.
And as a separation aspect, there are cases of the following 1-3.
1. Only oxygen is the product, and exhausted nitrogen is released to the atmosphere.
2. Only nitrogen is the product, and exhausted oxygen is released to the atmosphere.
3. Use oxygen-nitrogen products.
However, there are two types when the nitrogen purity is 90% or more and when the nitrogen purity is 99% or more.
[0037]
The gist of the method of the present invention resides in the following operation procedure in the separation apparatus or the adsorption separation system (5) shown in FIG.
The adsorption separation system (5) does not include a pretreatment device in the adsorption separation system shown in FIGS. 4 to 6 (targeting a large machine), and includes a pretreatment device in the adsorption separation system shown in FIGS. Although there are some basic aspects such as things (medium and small machine target) and others that differ depending on the separation specifications, the basic operation (the method of the present invention) is the same.
The adsorption separation system shown in FIG. 7 is an example of a system that uses only oxygen as a product, and the adsorption separation system shown in FIG. 8 is an example of a system that uses oxygen and low-purity nitrogen (90% or more) as a product. The separation system is an example of a system that uses oxygen and high-purity nitrogen (99% or more) as products.
[0038]
The gas bulk separation method of the present invention will be described with reference to an example in which oxygen and nitrogen are separated from air using an adsorption separation system (apparatus) having a two-column structure shown in FIG.
FIG. 4B shows an example of a system in the case where pressure energy in the step-down process is recovered by the expansion engine or the generator using the pressure energy recovery means (EX), which will be described in detail later.
FIG. 2 (A) is a pressure sequence showing the relationship [pressure to time in adsorption tower (A) and adsorption tower (B) to time], and FIG. 2 (B) is the final stage of each step (1) to (6). It is explanatory drawing which shows typically the gaseous-phase oxygen concentration in the adsorption tower (A) in and an adsorption tower (B). In FIG. 2B, symbols 1 to 4 indicate the oxygen concentration, 1 is an oxygen concentration of 21% or less, 2 is an oxygen concentration of 21%, 3 is an oxygen concentration of 21 to 90%, and 4 is an oxygen concentration of 90% or more. Indicates. Table 1 summarizes the relationship between these symbols 1 to 4 and the oxygen concentration.
[0039]
[Table 1]

[0040]
In the present invention, the individual steps of the following steps (1) to (6) are sequentially repeated in the adsorption tower (A) and the adsorption tower (B), so that oxygen and nitrogen are separated from the end of the adsorption tower at regular intervals. Are taken out alternately.
Note that the supply air of the adsorption separation system is “dry” air from which moisture, carbon dioxide, etc. have been removed in advance by a pretreatment device.
[0041]
Next, steps (1) to (6) will be described.
(1) Raw material pressurization
The raw material air is pressurized by a pump and sent to the adsorption tower (A) from the inlet end. And the pressure in the adsorption tower (A) is changed to the intermediate pressure (P _M ).
Oxygen rich gas is taken out from the outlet end, and the minimum operating pressure (P _L ) A cocurrent flow is supplied as purge gas to the adsorption tower (B) below.
▲ 2 ▼ Product delivery
The pressure in the adsorption tower (A) is the maximum operating pressure (P _H ), The feed of raw material air is stopped. Maximum operating pressure (P _H ) In the vicinity, the product take-off valve is opened, and product oxygen is taken out and sent to a product storage tank (not shown).
A part of product oxygen is supplied in parallel as a purge gas or repressurizing gas for the adsorption tower (B).
(3) Cocurrent flow decompression (1)
The pressure equalizing valve of the adsorption tower (A) is opened, and the adsorption tower (A) and the adsorption tower (B) are connected in parallel. By this operation, the pressure in the adsorption tower (A) decreases and the pressure in the adsorption tower (B) increases.
This operation is usually performed until the pressures of the two towers are equilibrated (equal pressure), but may be stopped in the middle of equilibration (partial pressure equalization).
(4) Cocurrent flow decompression (2)
After completion of the above steps, the outlet end of the adsorption tower (A) is opened to the atmosphere, and the residual gas in the tower is discharged into the atmosphere in parallel flow, and further sucked by a vacuum pump to below atmospheric pressure, and the minimum operating pressure (P _L ).
▲ 5 ▼ Purge
An oxygen-rich gas is fed into the adsorption tower (A) under the lowest operating pressure from the outlet end of the adsorption tower (B), and the nitrogen remaining in the adsorption tower (A) is purged in parallel flow.
▲ 6 ▼ Re-pressurization
[0042]
After the above steps (1) to (6) are completed, the adsorption tower (A) and the adsorption tower (B) are connected in parallel as in the step (3), and the adsorption tower (A) has an intermediate pressure (P _M ) And the pressure in the adsorption tower (B) is reduced.
The above operations (1) to (6) are referred to as one cycle operation (one cycle time, T seconds). In the case of a two-column configuration, the adsorption tower (A) and the adsorption tower (B) repeat the same operation with a delay of T / 2 hours.
In the case of the three-column configuration, the adsorption tower (A), the adsorption tower (B), and the adsorption tower (C) repeat the same operation with a delay of T / 3 time.
[0043]
Changes in the oxygen concentration in the adsorption tower (A) and the adsorption tower (B) will be described with reference to FIG.
In process (1) and process (2),
By feeding the raw material air into the adsorption tower (A) (indicated by arrows), the gas concentration distribution in the adsorption tower (A) is 2-3 as shown in FIG. 2B toward the inlet-outlet side. -4. Hereinafter, the same description method is used.
Product oxygen at the outlet end is collected as product. A part is supplied to the adsorption tower (B) as a purge gas (indicated by an arrow).
[0044]
The desorption of nitrogen begins by the cocurrent depressurization step of step (3) and step (4), and the concentration distribution of the gas in the adsorption tower (A) is changed from 1-2-3 to 1- 1 as shown in FIG. It changes as 1-2.
Air concentration (O ₂ = 21%) The following gas is discharged into the atmosphere as exhausted nitrogen (may be recovered as crude nitrogen).
[0045]
In step (5) (purge),
As oxygen is introduced from the inlet end of the adsorption tower (A) in the cocurrent direction, desorption starts sequentially from the nitrogen adsorbed at the inlet end and is pushed toward the outlet end.
The gas phase concentration in the adsorption tower (A) changes from 1-1-2 to 4-1-1 as shown in FIG. 2 (B).
In the two-column configuration system, a concentration step is generated in this step. Therefore, dry air (DA) is leaked from the end of the inlet so that 1-1-2 → 2-1-1 → 4-2-1. Also good.
[0046]
Process (6) (re-pressurization or re-pressure)
By reducing the pressure of the adsorption tower (B) and supplying it to the adsorption tower (A) in parallel, the oxygen concentration in the adsorption tower (A) is changed from 4-1-1 to 3-, as shown in FIG. It changes like 4-1. The oxygen-rich gas gradually moves to the outlet end.
Subsequent to the step (6), the step (1) (feeding of raw material air) starts, and as shown in FIG. 2 (B), as the pressure increases from 3-4-1 to 2-3-4, the outlet end portion becomes oxygen. Become rich.
In the pressurization step of the adsorption tower (A), the adsorption tower (A) is designed so that it gradually becomes rich in oxygen toward the outlet end, and in the pressure reduction process, it gradually becomes rich in nitrogen toward the outlet end. ), Controlling the amount of gas movement between the adsorption towers (B).
Also, when the adsorption tower (A) and the adsorption tower (B), or the adsorption tower (B) and the adsorption tower (A) are connected in parallel, there is no concentration step at the connection (so that mixing due to the concentration difference does not occur). Manipulate.
[0047]
The gas bulk separation method of the present invention will be described with reference to an example in which oxygen and nitrogen are separated from air using an adsorption separation system (apparatus) having a three-column structure shown in FIG.
FIG. 3A is a pressure sequence showing the relationship [pressure to time in the adsorption tower (A), adsorption tower (B) and adsorption tower (C)], and FIG. 3 (B) shows each step (1). It is explanatory drawing which shows typically the gaseous-phase oxygen concentration in an adsorption tower (A), an adsorption tower (B), and an adsorption tower (C) in the last stage of (6)-(6). Note that symbols 1 to 4 in FIG. 3B indicate the oxygen concentration, 1 is an oxygen concentration of 21% or less, 2 is an oxygen concentration of 21%, 3 is an oxygen concentration of 21 to 90%, and 4 is an oxygen concentration of 90% or more. Indicates. The relationship between the symbols 1 to 4 and the oxygen concentration is summarized in Table 1 above.
[0048]
Also in this case, the raw material gas is dry air of pretreated corners. As in the two-column configuration system, the adsorption tower (A), the adsorption tower (B), and the adsorption tower (C) are placed in T / 3 hours, and the following six-step operations (1) to (6) are performed. Are sequentially repeated.
(1) Raw material gas pressurization → product oxygen delivery
(2) Cocurrent decompression (1)
(3) Cocurrent flow decompression (2)
▲ 4 ▼ Purge
(5) Repressurization (1)
(6) Repressurization (2)
[0049]
Table 2 shows a comparison between the operation in the three-column configuration system and the operation in the two-column configuration system.
[0050]
[Table 2]

[0051]
That is, the operations (1) and (2) in the two-column configuration system are one individual operation (1) in the three-column configuration system, and the operation (6) in the two-column configuration system is ▲ in the three-column configuration system. There are two individual operations, 5 ▼ and (6).
[0052]
Next, individual operations of the three-column configuration system will be described so as not to overlap with the description of the two-column configuration system.
Focusing on the adsorption tower (A),
In step {circle around (1)}, raw material air is pressurized and fed into the adsorption tower (A), and product oxygen is taken out while increasing the pressure in the adsorption tower (A). The remainder is the pressure in the adsorption tower (B) P _L → P _M1 Pressurize to (intermediate pressure (1)).
In step {circle around (2)}, oxygen-rich gas is fed from the outlet end to the inlet end of the adsorption tower (B) while continuing the feed of raw material air, and the adsorption tower (A) is decompressed while the adsorption tower (A) is decompressed. B) pressure is intermediate pressure P _M1 → Intermediate pressure P _M2 The pressure is increased to (intermediate pressure (2)). Further, the adsorption tower (B) and the adsorption tower (C) are connected in parallel to flow the adsorption tower (A) → the adsorption tower (B) → the adsorption tower (C) and the gas, thereby purging the adsorption tower (C). . At this time, the gas phase concentration of each column is as follows as shown in step (2) of FIG.
Adsorption tower (A) [2-2-3] → Adsorption tower (B) [3-4-3] → Adsorption tower (C) [3-2-1]
The flow between the towers is controlled so that there is no level difference in oxygen concentration at each tower connection.
[0053]
In process (3), intermediate pressure P _M2 From operation minimum pressure P _L Depressurize until. The decompressed gas is released into the atmosphere or recovered as crude nitrogen. Alternatively, the active component in the decompressed effluent gas may be recycled and recovered to other towers in the same system through the path indicated by the dotted line in FIG. 5 via the pump (10). At this time, when oxygen is used as a product, the effluent in the early and late stages of pressure reduction is mainly collected, and when nitrogen is aimed at, the effluent in the middle stage of reduced pressure is recycled and recovered.
In step (4), the oxygen-rich gas at the outlet end of the adsorption tower (B) flows in the cocurrent direction of the adsorption tower (B) → the adsorption tower (C) → the adsorption tower (A), and purges the residual nitrogen in the adsorption tower (A). To do. At this time, the gas phase concentration in each column is as follows as shown in step (4) of FIG.
Adsorption tower (B) [2-2-3] → Adsorption tower (C) [3-4-3] → Adsorption tower (A) [3-2-1]
The inter-tower gas flow is controlled so that there is no difference in oxygen concentration at each tower connection.
[0054]
In step (5), part of the product oxygen from the adsorption tower (C) is reduced to the minimum operating pressure (P _L ) Leak to the lower adsorption tower (A), the pressure in the adsorption tower (A) is P _L → P _M1 Pressurize again.
In step {circle around (6)}, the adsorption tower (A) is connected to the intermediate pressure P by connecting the adsorption tower (C) → the adsorption tower (A) → the adsorption tower (B). _M1 → P _M2 Boost up to At the same time, the adsorption tower (B) is purged with oxygen-rich gas from the adsorption tower (A). At this time, the gas phase concentration of each column is as follows as shown in step (6) of FIG.
Adsorption tower (C) [2-2-3] → Adsorption tower (A) [3-4-3] → Adsorption tower (B) [3-2-1]
The inter-column flow is controlled so that there is no difference in oxygen concentration at each column connection.
The separation operation in the three-column configuration system has been described above.
[0055]
The separation operation in the three-column configuration system is advantageous compared to the separation operation in the two-column configuration system in that there is no significant oxygen concentration step between the adsorption towers and there is no idle operation period of the pump.
When the number of towers is four or more, the difference in oxygen concentration is less likely to occur than in a three-column system, but as the number of towers increases, the system becomes complicated and equipment costs increase. Therefore, a 2-4 tower configuration system is appropriate.
[0056]
The gas bulk separation method of the present invention will be described in general terms for the two-column configuration system and the three-column configuration system described above. (1) All the operations between the two columns are cocurrent flow operations. (2) Between the two columns The connection is a pressure approximation, and the pressure increase process of one tower is combined with the pressure decrease process of the other tower. It is characterized by controlling the flow between them.
[0057]
In the present invention, the enthalpy loss can be minimized because the normal temperature operation is used as a reference. However, the raw material air temperature may be kept at a constant temperature of, for example, 15 to 25 ° C. in order to smooth the oxygen production fluctuations during the season. It is also possible to operate at a temperature 10 to 15 ° C. higher than normal temperature. Increasing the operating temperature slightly increases the mass transfer rate and often has a favorable effect on the operation.
The operating pressure range in the present invention is generally in the vicinity of atmospheric pressure where an excessive load is not applied to the pump, but is classified into the following two types.
(1) Minimum pressure P _L When is at or above atmospheric pressure, it is called “pressurization method”. In this case, only a pressurizing pump is required.
(2) Minimum pressure P _L When is a vacuum pressure, it is called “vacuum method”. In this case, two types of pumps are required for pressurization and vacuum.
[0058]
The following examples can be given as examples of the working pressure range in the present invention (in the case of medium / small-sized aircraft).
(1) 0-7kg / cm ² G (gauge pressure), typically 0 to 4.5 kg / cm ² G (gauge pressure)
(2) 0.1-4 kg / cm ² abs (absolute pressure), typically 0.2 to 3.5 kg / cm ² abs (absolute pressure).
[0059]
An example of an adsorption separation system (hardware) suitable for carrying out the gas bulk separation method of the present invention will be described in more detail with reference to FIGS.
The gas separation operation by the two-column configuration system shown in FIG. 4A and the three-column configuration system shown in FIG. 5 is as described above.
In the method of the present invention, oxygen-rich gas and nitrogen-rich gas come out alternately from each column. At this time, there are the following three cases (1) to (3).
(1) FIG. 7 shows an example of an adsorptive separation system when only oxygen is used as a product and nitrogen is released to the atmosphere.
(2) FIG. 8 shows an example of an adsorption separation system when oxygen and low-purity nitrogen are used as products.
(3) FIG. 9 shows an example of an adsorption separation system when oxygen and high-purity nitrogen are used as products.
In the above cases (2) and (3) where nitrogen is the product, the vacuum method is generally preferred. In medium- and small-scale production systems, the pretreatment device (drying tower) is generally included in the latter separation device (adsorption separation system) without separating the pretreatment device and the separation device from each other. Is preferred.
[0060]
Such an example 7 The figure 8 Shown in In this case, the drying tower is generally regenerated for each circulation operation. In many cases, only oxygen is used as a product, so that the remaining waste nitrogen is flowed in a counter-current direction with respect to the drying tower to purge and regenerate the desiccant.
Increase the maximum operating pressure for large / ultra-large equipment (P _H It is desirable to recover the pressure energy in the step-down process with an expansion engine or a generator.
Actually, as shown in FIG. 4 (B), when the gas is transferred from the adsorption tower to the other adsorption tower while reducing the pressure, the pressure is lowered from high pressure through Ex (pressure energy recovery means) provided between the two towers. Expands to pressure. Further, when recovering the pressure energy of the gas at the final stage of decompression, it flows like the valve 14a (14b) -Ex-14c. Ex is an expansion engine or a generator, and pressure energy is recovered as mechanical energy or electric energy by Ex and stored in the system, which is used for energy saving of the system. V in FIG. 4B indicates a bypass valve.
[0061]
Two cases will be described for an example in which the pretreatment device is included in the adsorption separation system (example of air separation).
1) FIG. 7 shows an example of a two-column system intended solely for oxygen production.
A “valve sequence” for the operation of the adsorption separation system shown in FIG. 7 is shown in FIG.
7 denote the same parts as those shown in FIG. 4 (A). In FIG. 7, D _A , D _B Is a drying tower (filled with a desiccant such as silica gel, alumina gel, activated alumina, etc.), AR is raw material air, O ₂ : Product oxygen, WN represents exhausted nitrogen, and WA represents exhausted air.
In FIG. 7, valves 15a, 15b, 16a, 16b, 17a and 17b are added for the operation of the drying tower. The valve 18 is a valve that performs the same operation as the valve 15 in FIG. 4A (opening of the abnormal pressure rise in the pipe line (4)).
The separation operation according to FIG. 7 is basically the same as the separation operation shown in FIGS. 4 (A) and 10 (A).
FIG. 13 shows the opening / closing operation (valve sequence) of each valve in one cycle in the adsorption separation system of FIG.
Unnecessary gas in two stages of cocurrent decompression (4) and purge process (5) is generated by valve 15a → D _A → Valve 16a and D _A Flows in the counter-current direction, D _A The desorption of moisture, carbon dioxide, and the like adsorbed by the desiccant inside is promoted and released as a purge gas (WN) to the atmosphere.
The amount of gas required for purging is the operating pressure P _H And P _L Is 5 to 30% of the dry air supplied to the adsorption tower (A).
[0062]
2) FIG. 8 shows an example of a two-column configuration system for oxygen and crude (low purity) nitrogen.
An example of a “valve sequence” for operation of the adsorption separation system of FIG. 8 is shown in FIG.
The difference between the adsorptive separation system of FIG. 8 and the adsorptive separation system of FIG. 7 is that a vacuum pump (10) is provided, and valves 19 and 20 are provided around the vacuum pump (10) for smooth operation of the vacuum pump (10). , 21 and the points 14a, 14b.
The separation operation according to FIG. 8 is basically the same as described with reference to FIGS. 4 (A), 10 (A), 7 and 13.
For the adsorption tower (A), the cocurrent depressurization operation is performed using the valves 15a-D. _A The valve 16a → the vacuum pump (10) → the valve 21 → the regeneration operation leading to the atmosphere and the operation of pulling up to the vacuum pressure are performed separately. Since the gas at the rear stage is rich in nitrogen component, it is recovered into a nitrogen storage tank (not shown) via the valve 14a-vacuum pump (10) -valve 20.
[0063]
Preferred embodiments for carrying out the gas bulk separation method of the present invention include the following embodiments.
1. Using air as a raw material, oxygen (oxygen concentration 90% or more) is used as a product.
2. Using air as a raw material, oxygen (oxygen concentration of 90% or more) and / or nitrogen (nitrogen concentration of 99% or more) is used as a product.
3. The system for separation has 2 to 4 towers.
4). The automatic valve operating the adsorptive separation system is an on-off valve that operates with electric force and / or air pressure.
5. The small capacity machine is configured as a system in which the raw material mixed gas pretreatment device and the separation device are integrated, and performs integration and circulation operations.
6). The gas separation operation temperature should be around room temperature (25 ± 10 ° C).
7. The gas separation operating pressure is 0 to 4.5 kg / cm in the pressurization method. ² G, -0.8 to + 3.5kg / cm for vacuum method ² (However, for medium and small capacity machines).
8). When the component (A) is the target product, the feed of the raw material gas is stopped immediately before the leading edge of the adsorption zone of the component (B) reaches the end of the tower in the feed of the raw material gas into the tower. preferable. When the component (B) is the target product, the concentration of the component (A) in the effluent gas from the column end gradually decreases, and the feed of the raw material gas is stopped immediately before the inlet concentration and the outlet concentration become equal. Is preferred.
[0064]
[Action]
1. In the present invention, the countercurrent depressurization operation causing PSA loss is assumed to be a cocurrent depressurization operation, and in principle, all useful components are collected in the system, and the concentration gradient formed in the system is maintained through each individual operation. The entropy loss has been minimized, the thermal and cold energy generated in the system is all effectively utilized in the system, the enthalpy loss has been minimized, and the pressure energy is the pressure of other adsorption towers or expansion engines. By collecting with the energy recovery means, energy saving performance has been remarkably improved.
2. In the present invention, adsorbent production is achieved by using a simple configuration, using inexpensive components (mainly iron and adsorbent), and operating at high load by adopting an on-off valve and a pulse flow control method (PF). As a result, the material saving performance has been significantly improved.
3. The overall efficiency including the improvement of energy saving and material saving has been remarkably improved compared with the conventional deep cooling method and the conventional PSA, and for example, it has become possible to supply a large amount of inexpensive oxygen and nitrogen from the raw material air. .
4). The method of the present invention also enables an ultra-compact unit for small capacity machines that cannot be achieved by the deep cooling method.
5. According to the method of the present invention, oxygen and nitrogen can be produced together, which is extremely difficult with the conventional PSA.
[0065]
【Example】
EXAMPLES Next, although an Example demonstrates this invention further in detail, unless it deviates from the main point of this invention, it is not limited to an Example.
(Example 1)
The gas bulk separation method of the present invention is divided into a two-column adsorption separation system (apparatus) shown in FIG. 4 (A), the pressure in the adsorption tower (A) and the adsorption tower (B) in FIG. An example in which oxygen (useful gas) and nitrogen (unnecessary gas) are separated from air using a pressure sequence indicating the time] relationship and a valve sequence shown in FIGS. 10 (A) and 10 (B) will be described.
The adsorption tower (A) and the adsorption tower (B) contain adsorbents a and b that selectively adsorb unnecessary gas, respectively. The adsorption tower (A) and the adsorption tower (B) have the same specifications.
[0066]
A mixed gas (dry air) (DA) is fed from the lower side of FIG. 4A, and an unnecessary gas (nitrogen) is adsorbed and sent to the upper side.
The pump (1) sucks and pressurizes the raw air (AR), sends it to the pipe (2), and removes moisture, carbon dioxide, trace impurities, etc. in the air in the pretreatment device (3). , And sent to the pipe (4) as pressurized dry air (DA), and sent from the inlet end below the adsorption tower (A) and the adsorption tower (B) via the pipe (5a) and the pipe (5b). Enter.
The useful gas (oxygen) obtained from the upper side (exit end) of the adsorption tower (A) and the adsorption tower (B) passes through the pipe (6a) and the pipe (6b) to the product storage tank (7). (Not listed).
Useful gas (oxygen) and waste gas (nitrogen) are alternately sent to the pipe line (6a) and the pipe line (6b) at regular time intervals. The pipe line (8) is a path for releasing unnecessary gas. In addition, a vacuum pump (10) may be provided in the pipe line (8) to promote desorption of unnecessary gas.
Each on-off valve, 11a, 11b, 12a, 12b, 13a, 13b, 14a, 14b is a valve for opening and closing the passage of gas in the pipe line in which each is provided, and is required by a control unit (not shown). It opens and closes to accomplish the process.
[0067]
The on-off valves 11a and 11b contribute to the above feeding operation,
The on-off valves 12a and 12b contribute to the required gas (oxygen) sampling operation,
The on-off valves 13a and 13b are valves for connecting the adsorbing tower (A) and the adsorbing tower (B) or the adsorbing tower (B) and the adsorbing tower (A) in parallel flow. Contributes to "operation".
The on-off valves 14a and 14b contribute to the release of unnecessary gas (nitrogen) to the atmosphere.
The on-off valve (15) contributes to alleviating or opening the excessive pressure rise in the pipe line (4) during the valve switching operation.
・ Pressure gauge (P _A ), (P _B ) Monitors the pressure inside the adsorption tower (A) and the adsorption tower (B), respectively.
[0068]
In the first embodiment, each on-off valve is controlled as shown in FIGS. 10A and 10B in the valve sequence during the process of one cycle, and the pressure gauge (P _A ), (P _B The pressure change seen in FIG. 2 is as shown in FIG.
In FIGS. 10A and 10B, each on-off valve is opened only during the hatched period and is stopped during the other periods.
The pressure change in FIG. 2 (A) shows a schematic diagram, and in reality, it becomes a deformation curve accompanied by transient fluctuations in each pipe line and each adsorption tower by opening and closing of each on-off valve.
[0069]
The order of each operation in one cycle process will be described.
Basically, each pressure change in each adsorption tower (A) and adsorption tower (B) is changed to two phases by one phase period (T seconds), for example, T = 60 seconds 1/2, that is, a phase difference of 30 seconds. Specifically, the operation is performed with a change curve. Specifically, the pressure change in the adsorption tower (A) is the pressure change of the first phase having the change shown by the broken line in the upper part of FIG. 2 (A). As is done, the operation of the adsorption tower (B) is performed so that the pressure change in the second phase has the change indicated by the broken line in the lower part of FIG. 2 (A).
Each pressure change is the maximum pressure P _H And minimum pressure P _L And an intermediate pressure P obtained by dividing the distance between them into two equal parts. _M The three pressure points are operated to pass through.
[0070]
First, when the operation is started, each pressure in the adsorption tower (A) and the adsorption tower (B) follows various transitional courses for several cycles, but eventually, one cycle of FIG. Starting point (T _S ), The pressure in the adsorption tower (A) _M In addition, the pressure in the adsorption tower (B) _M Or in the vicinity.
Starting point T _S Will be described below in the order of steps based on the operation on the adsorption tower (A), that is, the pressure change shown in the upper part of FIG. 2 (A).
[0071]
Process (1) Raw material pressurization operation 0 (= T _S ) ~ 25 seconds
Opening and closing valve 11a is the starting point T _S Open for more 25 seconds.
An operation of pressurizing and feeding dry air, that is, a raw material gas, into the adsorption tower (A) is performed, and the pressure of the adsorption tower (A) is changed to an intermediate pressure P. _M To maximum operating pressure P _H The waste gas (nitrogen) is adsorbed by the adsorbent (a), and the useful gas (oxygen) is sent to the upper side (exit end) of the adsorption tower (A). At the same time, the on-off valve 14b is opened for 20 seconds so that the pressure in the adsorption tower (B) can be discharged to the pipe (8), whereby the pressure in the adsorption tower (B) is reduced to the intermediate pressure P. _M To minimum operating pressure P _L Migrate to At this time, the vacuum pump (10) is used for suction and the minimum operating pressure P _L Can be reduced to atmospheric pressure or lower.
Note that the start point (T _S 15 seconds later, the on-off valve (13a) is opened for 5 seconds, and the oxygen rich gas at the outlet end of the adsorption tower (A) is reduced to the minimum operating pressure P. _L The adsorption tower (B) is flowed in the co-current direction from the inlet end to purge the adsorption tower (B). By this operation, desorption of the residual unnecessary gas (nitrogen) in the adsorption tower (B) is promoted and released to the atmosphere through the valve (14b) and the pipe line (8).
After the purge operation is completed, the on-off valve 13a is opened for a short time, and the pressure in the adsorption tower (B) is kept higher than the atmospheric pressure [shown by 5a in FIGS. 10A and 10B].
[0072]
Process (2) Product removal operation (20-25 seconds)
When the pressure in the adsorption tower (A) increases due to the operation of the step (1) and reaches the vicinity of the maximum operating pressure, the on-off valve (12a) is opened, and useful components (oxygen) are collected.
That is, the starting point (T _S 20 seconds later, the on-off valve (12a) is opened for 5 seconds, and the useful component (oxygen) is taken out from the outlet end of the adsorption tower (A).
[0073]
Process (3) Cocurrent flow decompression (1) operation (25-30 seconds (T _M ))
Starting point T _S When 25 seconds have elapsed, the on-off valve 11a is closed, the valve 13a is opened, and the adsorption tower (A) and the adsorption tower (B) are connected in parallel. By this operation, the pressure in the adsorption tower (A) is increased to the maximum operating pressure (P _H ) To intermediate pressure (P _M ) And the pressure in the adsorption tower (B) is the minimum operating pressure (P _L ) To intermediate pressure (P _M ).
That is, when the pressures in the adsorption tower (A) and the adsorption tower (B) are equilibrated, the gas transition from the adsorption tower (A) to the adsorption tower (B) stops (referred to as pressure equalization).
During the pressure equalization operation period, the on-off valve (15) is opened for 5 seconds to avoid an abnormal increase in pressure in the pipe (4).
[0074]
Process (4) Cocurrent decompression (2) operation (30 (T _M ) -45 seconds)
Starting point (T _S ) 30 seconds from the middle point (T _M ). T _S ~ T _M The operations of steps (1) to (3) are completed in (30 seconds). After completion of the operation in step (3), the valve (14a) is opened for 20 seconds. The pressure in the adsorption tower (A) is intermediate pressure (P _M ) To minimum operating pressure (P _L ).
[0075]
Process (5) Purge operation (45-50 seconds)
The operation of the step (4) performed following the operation of the step (3) is stopped in 15 seconds, but the valve (14a) is kept open. That is, the adsorption tower (A) has a minimum operating pressure (P _L ).
The midpoint of one cycle (T _M 15 seconds later, the valve (13b) is opened for 5 seconds, and the oxygen-rich gas at the outlet end of the adsorption tower (B) is introduced in the cocurrent direction from the inlet end of the adsorption tower (A), and remains in the adsorption tower (A). Promotes desorption of unnecessary components.
The desorbed unnecessary gas (exhaust nitrogen) is sent to the pipe line (8) through the valve (14a) and released to the atmosphere.
[0076]
Process (6) Repressurization operation [55-60 seconds (T _E ]]
T _M The valve 14a opened in step S5 is closed after 20 seconds.
The valve 13b is opened for a short time for 5 seconds until the repressurization operation is started, and the inside is kept at a positive pressure (above atmospheric pressure) [indicated by 5a in FIG. 11 (B)].
T _M 25 seconds later, the valve 13b is opened for 5 seconds, and a repressurization operation is performed.
During this operation, the valves at the inlet to outlet ends of the adsorption tower (A) and adsorption tower (B) are all closed except for the valve 13b. By opening the valve 13b, two towers are connected in the parallel flow direction of the adsorption tower (B) outlet-adsorption tower (A) inlet, and the adsorption tower (B) is P _H → P _M The adsorption tower (A) is P _L → P _M The pressure is restored until the material is ready.
Step (6) After the operation is completed, the valve 11a is opened again, and the second cycle starts. Starting point T _S Then, the valve 15 is opened for 55 to 60 seconds to avoid an abnormal pressure increase in the pipe line (4).
[0077]
Although the opening / closing operation of each valve in one cycle has been shown mainly focusing on the adsorption tower (A), the same operation is performed with a delay of 30 seconds for the adsorption tower (B).
Related operations between the adsorption tower (A) and the adsorption tower (B) are as shown in FIGS. 10 (A) and 10 (B).
There is another example in which the operation is stopped and the operation of the step (4) is started while the pressures of the two towers connected in parallel flow by the operation of cocurrent decompression (1) are balanced (partial pressure equalization method).
There are also other examples of connecting two towers while continuing to pressurize the high pressure tower or continue to depressurize the low pressure tower.
[0078]
In the operation of the method of the present invention, in order to improve the overall efficiency, it is necessary to quickly and accurately control the amount of gas flowing into and out of the adsorption tower.
Generally, a throttle mechanism such as an orifice, a diaphragm control valve, etc. are attached to the pipe line near the automatic open / close valve, and the flow rate of gas flowing through the pipe line when the valve is opened / closed is adjusted before entering continuous operation. Since the start-up operation becomes complicated, or adding an adjusting means in addition to the automatic on-off valve may complicate the configuration of the device and increase the price of the device, or lead to energy loss due to flow path resistance. In the present invention, all the valves to be used are unified on-off valves, and the optimum gas amount for the individual operations of the above six steps (1) to (6) is intermittently based on the precise sequence of the on-off valves. It is preferable to control by a manual opening / closing operation.
[0079]
In FIG. 10A, the purge donating valve 13a or 13b is intermittently opened and closed as shown in FIG. 10B. In the first embodiment, the valve 13a is opened and closed as 15.0-15.5, 17.5-18.0, 20.0-20.5, and the oxygen-rich gas is supplied to the minimum operating pressure P. _L Are sent as three continuous pressure waves to the adsorption tower (B). The total flow rate of the two pulses of the first pulse and the second pulse is controlled to be a gas amount necessary for the “purge operation”. The third pulse (indicated by 5a) is an operation for maintaining the pressure in the adsorption tower higher than the atmospheric pressure. The above rapid and precise flow control method is called “Pulsed Flow Control Method” (PF).
[0080]
This PF will be described in detail with reference to FIGS.
FIG. 16 is a model diagram of a small simulator for individual operation of the present invention.
In FIG. 16, A is an adsorption tower, V ₁ , V ₂ Is an on-off valve, a is an adsorbent, P ₁ , P ₂ Is a pressure sensor, R is a reservoir, and ΔP is a differential pressure.
An example of experimental operation is shown below.
After being activated, the adsorbent a is filled with nitrogen, and is placed under atmospheric pressure or vacuum pressure so that the initial conditions are met. Initial pressure P ₂ And
Oxygen is put into the reservoir (R) and a constant pressure (P ₁ ) (P ₁ > P ₂ ).
On-off valve V ₁ For 0.1 second, and the temporal change of the pressure difference ΔP in the adsorption tower (A) is recorded in a graphic form. The results are shown in FIG.
On-off valve V ₁ Is set to 0.2, 0.3 seconds, etc., and the temporal change of ΔP of the adsorption tower (A) is graphically recorded. The result obtained after 0.2 seconds is shown in FIG.
[0081]
The chevron and waveforms of A and B in FIG. 17 are compared.
As shown in FIG. 17A, when Δt = 0.1, an acute angle shape in which the peak portion of the chevron is broken.
As shown in FIG. 17B, when Δt = 0.2, the crests are almost symmetrical and approximate to a sine wave. In the latter case, it shows that a certain amount of gas mass is smoothly propagating in the column as a pressure wave. The amount of gas mass or gas wave at this time indicates the minimum optimum gas amount.
H in the waveform diagram of B of FIG. _B Is related to gas propagation velocity and T _B Indicates the waiting time (pause) of the first wave and the second wave.
In the pulse flow control in the pulse operation of the step (5) in the first embodiment, the operation of 0.5 pulse-2.0 pause (first pulse) is performed in the second, third and third operations.
The flow rate of one pulse at this time is represented by the following formula (1) (empirical formula).
[0082]
[Equation 3]

[0083]
(Example 2)
The gas separation method of the present invention is a three-column adsorption separation system (apparatus) shown in FIG. 5, [Adsorption tower (A), adsorption tower (B) and adsorption tower (C) shown in FIG. An example in which oxygen and crude nitrogen are separated from air by using a pressure sequence indicating the relationship between the pressure and time] and a valve sequence shown in FIG. 11 will be described.
Each of the adsorption tower (A), the adsorption tower (B), and the adsorption tower (C) has the same specifications. Inside the adsorption tower (A), adsorption tower (B) and adsorption tower (C), an adsorbent (MS-5A) that selectively adsorbs nitrogen gas is packed in a column.
Among the symbols in FIG. 5, the same symbols as those described in the first embodiment (FIG. 4A) indicate similar functions. DA indicates pressurized dry air.
The on-off valves 21a, 21b, and 21c contribute to the operation of feeding pressurized dry air,
The on-off valves 22a, 22b, 22c contribute to the product oxygen collection operation,
The on-off valves 23a, 23b, 23c contribute to the parallel flow connection operation between the two towers,
The on-off valves 24a, 24b, and 24c contribute to the crude nitrogen collection operation.
The on-off valves 26a, 26b, and 26c contribute to the active component recovery operation.
-Pipe line 9a, 9b, 9c is a pipe line for connecting two towers in parallel flow.
・ P _A , P _B , P _C Are pressure gauges for monitoring the pressure inside the adsorption tower (A), the adsorption tower (B), and the adsorption tower (C), respectively.
[0084]
Each on-off valve is controlled as shown in FIG. 11 in the valve sequence during the process of one cycle. _A , P _B , P _C The change in pressure is as shown in FIG. In FIG. 11, each on-off valve is opened only during the hatched period and is stopped during the other periods. In FIG. 11, the numbers in the hatched portions indicate the order of steps (1) to (6) focusing on the adsorption tower (A).
The pressure change in FIG. 3 (A) shows a schematic diagram, and in reality, it becomes a deformation curve with transient fluctuations in each pipe line and each adsorption tower by opening and closing of each on-off valve.
The operation will be described in the order of each operation in one cycle process.
Starting point T _S Will be described mainly with respect to the operation on the adsorption tower (A), that is, the pressure change shown in the upper part of FIG.
[0085]
Process (1) Raw material pressurization 0 (= T _S ) ~ 20 seconds
Pressurize and feed dry air into the adsorption tower (A), and the pressure in the adsorption tower (A) (P _A Intermediate pressure P) _M2 To maximum operating pressure P _H Raise to Nitrogen in the air is adsorbed by the adsorbent column, and oxygen is sent to the outlet end of the adsorption tower (A). During this operation period, the pressure in the adsorption tower (A) is P _H When the vicinity is reached, the oxygen delivery valve 22a is opened for 5 seconds to deliver a predetermined amount of oxygen to the conduit (7). A product oxygen storage tank (not shown) is connected to the pipe line (7), and is sent from there to the consumption end.
Also, the valve 23a is opened for 1.0 second, and the minimum operating pressure P _L Re-pressurization (1) of the lower adsorption tower (B) is performed (indicated by 5a in FIG. 11).
[0086]
Process (2) Cocurrent flow decompression (1) 10-20 seconds
While continuing to feed dry air to the adsorption tower (A), the valve 23a is opened for 10 seconds, the adsorption tower (A) and the adsorption tower (B) are connected in parallel, and the outlet end of the adsorption tower (A) The oxygen-rich gas in the part is recovered in the adsorption tower (B), the valve 23b is opened after a while, and the adsorption tower (B) is set to the intermediate pressure P _M1 To P _M2 Until re-pressurization is performed. At the same time, the adsorption tower (A) has a maximum operating pressure P _H To P _M2 Step down the pressure.
[0087]
Process (3) Cocurrent flow decompression (2) 20-30 seconds
The valve 24a is opened for 10 seconds. The nitrogen rich gas remaining in the adsorption tower (A) is sent to the pipe line (8). From there, it is sent to a nitrogen storage tank (not shown). When oxygen production is aimed, it is released into the atmosphere via the pipe (8). The pressure in the adsorption tower (A) is the minimum operating pressure P _L To descend. When recovering the oxygen content in the decompressed effluent gas, it is recycled and recovered to the adsorption tower (B) through the path indicated by the dotted line with the valve 20b-pump (10) -valve 26b.
[0088]
Process (4) Purge 30-40 seconds
During this operation period, the adsorption tower (A) has a minimum operating pressure P _L Below.
As shown in FIG. 3A, the oxygen-rich gas for purging flows in the cocurrent flow direction from the adsorption tower (B) → the adsorption tower (C) → the adsorption tower (A), and the nitrogen-rich gas remaining in the adsorption tower (A). Is extruded to the adsorption tower (A) to the outlet end, and is sent to the pipe line (8) through the valve 24a.
What is important in this operation is that the flow rate must be adjusted so that the pressure change in each column follows the pressure sequence diagram [Fig. 3 (A)] so that there is no step in the concentration gradient at the connection between the two columns. It is.
[0089]
Process 5) Re-pressurization (1) 41-42.0 seconds
The valve 23c is opened for 1.0 second, and the adsorption tower (A) is repressurized (1). Figure 11 It is shown in the middle step 5). The pressure in the adsorption tower (A) is about 0.25 kg / cm. ² Go up to G.
[0090]
Process (6) Repressurization (2) 50.0-60.0 seconds
The valve 23c is opened for 10 seconds, the adsorption tower (C) and the adsorption tower (A) are connected in parallel, and the adsorption tower (A) is repressurized (2) while reducing the pressure in the adsorption tower (C). After a while, the adsorption tower (A) and the adsorption tower (B) are connected in parallel, and the purge gas is supplied from the adsorption tower (A) to the adsorption tower (B). The pressure in the adsorption tower (A) is 0.25 kg / cm ² → 2.5kg / cm ² Boost up to
[0091]
As mentioned above, the opening / closing operation of each valve in one cycle time 60 seconds was shown mainly focusing on the adsorption tower (A), but the adsorption tower (B) and the adsorption tower (C) are also delayed by 60/3 = 20 seconds respectively. Similar operations are performed. The related operations between the adsorption tower (A), the adsorption tower (B), and the adsorption tower (C) are as shown in FIG.
[0092]
In the operation of a system with three or more towers, the flow adjustment is important because the three towers are connected in parallel and the gas flows. The decompression operation commonly used in the two-column system is stopped when the two towers are connected in parallel and the pressure is equilibrated. At this time, it is not necessary to consider the control of the gas transfer amount (total amount). However, it is necessary to adjust the flow rate so that the pressure drop (rise) is linear on the pressure sequence diagram and just ends in a predetermined time.
In the case of a three-column system, care must be taken that both the amount of gas transferred (total) and the speed of movement (as along the pressure sequence) are optimal values.
[0093]
The four-column system and the separation operation can be executed in the same way as in the case of the three-column system.
A description will be given of an example in which oxygen and crude nitrogen are separated from air using the four-column adsorption separation system (apparatus) shown in FIG. 6 and the valve sequence shown in FIG. In the case of a four-column system, six steps (1) to (6) are performed as in the case of a three-column system. Table 3 shows the results of comparing the six steps (1) to (6) in the case of the four-column system and the six steps (1) to (6) in the case of the three-column system.
[0094]
[Table 3]

[0095]
It differs from a three-column system in that “cocurrent decompression and repressurization are divided into three stages”. However, the basic idea is the same.
[0096]
(Example 3)
An example of producing oxygen and high-purity nitrogen from air using the two-column adsorption separation system (apparatus) shown in FIG. 9 and the valve sequence shown in FIG. 15 will be described.
Adsorption tower: inner diameter 53m / m x length 230m / m x 2 towers
Adsorbent: MS-5A (filling amount in adsorption tower (A); 298 g, filling amount in adsorption tower (B); 305 g)
The two-column adsorption / separation system (apparatus) shown in FIG. 9 and the two-column basic adsorption / separation system shown in FIG. 4 are used to produce high-purity nitrogen in the case of FIG. ) Are the same except for the symbols in FIG.
DA: Pressurized dry air
O ₂ : Product oxygen (purity 93% or more)
HN ₂ : High purity nitrogen (purity 99.5% or more)
WA: Exhaust air
R _O : Product oxygen storage tank
R _N : Product nitrogen storage tank
10: Vacuum pump
Each valve is an on-off valve.
In Example 3, each valve is controlled as shown in FIG. 15 in the valve sequence during one cycle process, and is opened only during the hatched period.
The hatched part numbers indicate the order of steps with respect to the adsorption tower (A).
[0097]
One cycle operation consists of the following eight steps (1) to (8).
The difference from the basic sequence of the two-column configuration shown in Example 1 is that the “(3) cocurrent depressurization (2)” and “(4) purge operations” in the basic sequence are for “high purity nitrogen production”. Only “nitrogen replacement operation” and “nitrogen recovery operation” are entered.
The separation operation of this example will be described below with a focus on the adsorption tower (A).

[0098]
Steps (1), (2), (3), (4), (7), and (8) are as described in the first embodiment. Steps (5) and (6) will be described.
Process (5) Nitrogen replacement 30.0-37.5 seconds
Start point T of one cycle _S 30.0 seconds later, the four valves 20a, 20b, 17a, 18a are opened and the nitrogen storage tank R _N The high-purity nitrogen inside is fed in the cocurrent direction from the inlet end of the adsorption tower (A), the oxygen content remaining in the gas phase part in the adsorption tower (A) is pushed to the outlet end, passes through the valve 18a, and into the air Is released. This operation is stopped when high purity nitrogen reaches the outlet end of the adsorption tower (A).
[0099]
Process (6) Nitrogen recovery 37.5-50.0 seconds
When the operation of step (5) is completed, the valves 14a and 20c are opened, and the adsorption tower (A) is vacuumed by the vacuum pump (10). By this operation, nitrogen existing in the gas phase in the adsorption tower (A) and the adsorption layer is sucked and the nitrogen storage tank (R _N ). Pressurized from there, high purity nitrogen (HN ₂ ) And sent to the consumer end. The nitrogen storage tank preferably has a flexible structure.
Oxygen is purged and supplied to the adsorption tower (A) under vacuum after the operation of steps (5) and (6) is performed by intermittently opening the valve 13b (PF control method).
In this example, two pulses of 0.5 seconds are operated.
The flow of gas into and out of the adsorption tower (A) and the adsorption tower (B) and the operating state of the pump in the above one-cycle operation are apparent from the valve sequence shown in FIG.
Thus, 90% or more of oxygen and 99.5% or more of nitrogen were alternately produced every 30 seconds from the adsorption tower (A) and the adsorption tower (B).
[0100]
The separation operation of Example 3 is not limited to a two-column system, and can be performed in a system having a three-column configuration or more. In a system with three or more towers, it becomes easy to eliminate the idling period of the pump (1) and the vacuum pump (10).
[0101]
The valve seats shown in Examples 1 to 3 and FIGS. Ke The examples show typical examples and can be implemented in other various modifications, but all fall within the scope of the present invention without departing from the gist of the present invention.
[0102]
【The invention's effect】
The gas bulk separation method of the present invention uses an adsorption separation system (apparatus) with a simple configuration, uses inexpensive materials, and is compact in the adsorption separation system (apparatus). However, the price of the apparatus is remarkably reduced, and the constituent materials are iron and stone (adsorbent) that are harmless to the environment, so that it is much more economical considering the disposal cost. In the gas bulk separation method of the present invention, the gas flows in a certain direction while changing the pressure in a certain period, and through this flow process, the concentration gradient is maintained constant (isentropic process), and is generated in the adsorption separation system. Effective use of adsorption heat and desorption heat (cold heat) in the system (isoenthalpy process), pressure energy is used for boosting other adsorption towers, or mechanical and / or electrical energy by expansion engines, etc. By collecting, it becomes a thermodynamic energy saving process.
As described above, since the gas bulk separation method of the present invention is an energy saving and material saving process, the overall efficiency is remarkably improved, and a large amount of inexpensive oxygen, nitrogen or hydrogen is separated and supplied from the raw material mixed gas. It became possible to do.
[0103]
In recent years, with the growing energy and environmental problems, large-scale development projects for oxygen blast furnace method, smelting reduction iron method, coal gasification combined power generation, new iron production method such as high temperature fuel cell, and new power generation system are in progress. Generation technology consumes a large amount of gas such as oxygen and nitrogen.
The gas bulk separation method of the present invention greatly contributes to the economic establishment as a mass and inexpensive gas supply means for the next generation technology.
[0104]
In addition, the gas bulk separation method of the present invention enables a small and compact gas separator that can be mounted on an automobile.
In other words, it is expected to have an effect that can be mounted on a diesel vehicle and used as an oxygen flame for particulate burnout, or as an oxygen, nitrogen source, hydrogen separator, etc. .
[0105]
The gas bulk separation method of the present invention not only separates oxygen and nitrogen from air, but also other mixed gases (for example, H ₂ -CO ₂ , H ₂ -N ₂ , N ₂ -CO etc.) can also be applied.
As described above, the gas bulk separation method of the present invention has a great industrial utility value.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a basic system for carrying out the method of the present invention.
FIG. 2 (A) shows the pressure sequence of each tower of the two-column configuration system according to the present invention, and (B) is an explanatory diagram showing the change in the gas phase concentration distribution in each adsorption tower.
FIG. 3 (A) shows a pressure sequence of each tower of a three-column configuration system according to the present invention, and (B) is an explanatory diagram showing a change in gas phase concentration distribution in each adsorption tower.
FIG. 4A is an explanatory diagram showing a basic system example (two-column configuration) according to the present invention, and FIG. 4B is a pressure energy recovery means (EX) that expands pressure energy in the pressure reduction process. It is explanatory drawing which shows the deformation | transformation aspect of the basic system example (2 tower structure) shown to (A) in the case of collect | recovering with an engine or a generator.
FIG. 5 is an explanatory diagram showing an example of a basic system having a three-column structure according to the present invention.
FIG. 6 is an explanatory diagram showing an example of a basic system with a 4-tower configuration according to the present invention.
FIG. 7 is an explanatory diagram showing an example of a basic system having a two-column configuration and a drying tower according to the present invention.
FIG. 8 is an explanatory diagram showing an example of a basic system including a drying tower and a vacuum pump in a two-column configuration according to the present invention.
FIG. 9 is an explanatory diagram showing an example of a basic system including a vacuum pump, a product oxygen storage tank, and a product nitrogen storage tank in a two-column configuration according to the present invention.
FIG. 10 is an explanatory diagram showing an example of a valve sequence for operating the basic system shown in FIG. 4;
11 is an explanatory diagram showing an example of a valve sequence for operating the basic system shown in FIG. 5. FIG.
12 is an explanatory diagram showing an example of a valve sequence for operating the basic system shown in FIG. 6. FIG.
FIG. 13 is an explanatory diagram showing an example of a valve sequence for operating the basic system shown in FIG. 7;
14 is an explanatory diagram showing an example of a valve sequence for operating the basic system shown in FIG. 8. FIG.
15 is an explanatory diagram showing an example of a valve sequence for operating the basic system shown in FIG. 9. FIG.
FIG. 16 is a model diagram of a small simulator for performing a pulsed opening / closing operation test of an automatic valve by the “pulse flow control method” (PF).
17 is a graph showing temporal changes in the pressure difference (ΔP) in the adsorption tower when tested using the small simulator shown in FIG.
[Explanation of symbols]
DA Dry air
A, B, C, D Adsorption tower
a, b Adsorbent
AR Raw material air (Pressurized dry air)
D _A , D _B Drying tower
Ex Pressure energy recovery means
V Bypass valve
O ₂ Product oxygen
N ₂ Product nitrogen
HN ₂ High purity nitrogen
WA exhaust air
WN Exhaust nitrogen
1 pump
2, 4, 5a, 5b, 5c, 6, 6a, 6b, 6c, 7, 7a, 7b, 8, 9a, 9b, 9c
3 Pretreatment device
5 Separation device (or system)
27, 28 Product removal automatic valve
10 Vacuum pop
11a-17a, 11b-17b, 14c, 15, 18, 18a, 18b, 20a-20e, 19-21, 21a-25a, 21b-25b, 21c-25c, 26a-26d, 31a-34a, 31b-34b, 31c-34c, 31d-34d, 35a, 35b, 36a, 36b Automatic (open / close) valve

Claims (18)

Moisture, carbon dioxide gas, etc. with a small amount of the raw material mixed gas containing the hard-to-adsorb component (A) and the easy-to-adsorb component (B) as compared with the component (A) and component (B) in the raw material mixed gas The adsorption tower of the adsorption separation system comprising at least two adsorption towers filled with an adsorbent capable of selectively adsorbing the component (B) in a column or a layer after removing the easily condensable gas in the pretreatment device Is a gas bulk separation method for obtaining component (A) and / or component (B) from one end (inlet end) to the other end (outlet end). By repeating the sequence operation of (6) through the other end (exit end), component (A) and / or component (B) are alternately produced as products from the other end (exit end) at a constant time with low power consumption and high overall efficiency. Parametric gas chromatograph characterized by The method of bulk separation gas by Rafi.
(1) The raw material mixed gas is passed to the inlet end of the adsorption tower, the pressure in the tower is increased from the intermediate pressure to the maximum operating pressure, and the component (B) in the raw material mixed gas is selectively adsorbed, And the gas rich in component (A) and / or component (A) is taken out from the other end (outlet end).
(2) While continuing the raw material supply, the gas rich in component (A) and / or component (A) is taken out from the outlet end near the maximum operating pressure.
{Circle around (3)} The raw material supply is stopped, the adsorption tower is depressurized in the parallel flow direction, and the reduced pressure gas does not pass to the inlet end of another adsorption tower that is in the same circulation operation and whose pressure rises.
(4) Continue depressurization and set the atmospheric pressure or the atmospheric pressure to a vacuum pressure. The gas released and / or sucked from this adsorption tower is released to the atmosphere, recovered to another adsorption tower, or the component ( B) Take the product out of the system.
(5) A gas rich in component (A) and / or component (A) is introduced as a purge gas in the co-current direction from the other adsorption towers in the same circulation operation to the adsorption tower under the lowest operating pressure. The component (B) is replaced with the component (A), and the gas rich in the component (B) and / or the component (B) is taken out from the outlet end of the adsorption tower.
(6) After the above operation is completed, the gas from the other adsorption tower whose pressure is approximately the same during the circulation operation and the pressure is decreasing is passed to the inlet end to increase the pressure to the intermediate pressure of the operation. 2. The method according to claim 1, wherein the step (3) is performed while the supply of the raw material mixed gas is continued. 2. The method according to claim 1, wherein the pressure reducing operation in step (3) and step (4) and the pressure increasing operation in step (6) are performed stepwise. 2. The method according to claim 1, wherein the raw material mixed gas is air and the product gas is 90% or more of oxygen and / or 90% or more of nitrogen. 2. The method of claim 1, wherein the adsorbent is a nitrogen-selective adsorptive zeolitic molecular sieve material. The method of claim 1, wherein the adsorption separation system comprises two adsorption towers. The method of claim 1, wherein the adsorption separation system comprises three or more adsorption towers. The method according to claim 1, wherein the effluent gas of step (1) is supplied to another adsorption tower as a purge gas of step (5), and component (A) of step (2) is used as a product. The method according to claim 1, wherein the effluent gas of step (2) is supplied to another adsorption tower as a purge gas of step (5), and the component (A) of step (1) is used as a product. The method according to claim 1, wherein the component (B) sucked by the cocurrent reduced pressure gas and / or pump in step (4) is used as a product. A pretreatment tower filled with a pretreatment adsorbent selected from silica gel, activated carbon, alumina gel, activated alumina, and zeolite is provided in the adsorption separation system, and the reduced pressure and / or purge discharge gas in step (4) and step (5) is provided. 2. A method according to claim 1, characterized in that a part of is supplied as a regeneration purge gas for the pretreatment tower. Effective component in gas adsorbed from column (4) and step (5) [component (A) when target product is component (A), component (B) when target product is component (B)] 2. The method according to claim 1, wherein the process is recycled to another adsorption tower in the same system through a pump. In the adsorption separation system composed of three or more towers, the individual operation of connecting two adsorption towers targets two adsorption towers of approximate operating pressure, using the pressure difference from one adsorption tower to another adsorption tower, 8. The gas according to claim 7, wherein a gas is allowed to flow in a co-current direction, a pressure drop in one adsorption tower and a pressure rise in another adsorption tower are performed, and a purge operation is performed on the adsorption tower under a minimum operating pressure. Method. When two adsorption towers are connected in an adsorption separation system composed of two or more towers, the gas phase concentration distribution in the adsorption tower in which the pressure in the adsorption tower is in the process of rising is such that the component (A) becomes rich toward the outlet end. The gas phase concentration distribution in the adsorption tower in which the pressure in the adsorption tower is decreasing is such that the component (B) becomes rich toward the outlet end, and between the outlet concentration of one adsorption tower and the inlet concentration of another adsorption tower. The method according to claim 1, wherein the amount of gas transferred is controlled so that there is no step. The component (B) in step (4) is once recovered in the intermediate tank, and prior to step (5), the component (B) in the intermediate tank is recirculated to the inlet end of the adsorption tower via a pump. The inside is replaced with the component (B), and then the gas in the adsorption tower and the component (B) in the adsorbent are sucked with a pump, and the component (B) is recovered as a high-purity product. Item 11. The method according to Item 10. The method according to claim 6, wherein two adsorption towers are connected in a parallel flow direction to perform pressure equalization or partial pressure equalization in a two-column adsorption separation system. 2. The method according to claim 1, wherein the pressure in step (3) and (4) is reduced through pressure energy recovery means such as an expansion engine, and pressure energy is recovered as electric and / or mechanical energy. In a simulator test for moving gas by connecting two adsorption towers with a pressure difference via an automatic on-off valve, the open time (Δti) of this automatic on-off valve is used as a parameter. Measure the time (t) change in the differential pressure (ΔP) between the inlet end and the outlet end of the adsorption tower and plot it into a figure (vertical axis: ΔP, horizontal axis: t). Δti for a sine wave approximate wave type is a pulse time, a value obtained by subtracting Δti from a half-wave width is ΔZi, and a gas amount (Vi) passing through the automatic on-off valve is expressed by the following equation (1). When set △ t ₁ (open)-△ Z ₁ (closed)-△ t ₂ (open)-△ Z ₂ (closed) ...-△ ti (open)-△ Zi (closed) valve opening / closing sequence (Valve opening time-time relationship) Necessary and sufficient gas transfer amount (ΣVi) and gas for the individual operations of steps 1) to 6) above The method according to claim 1, further comprising: controlling a moving speed of [ΣVi / (Σti + ΣZi)].

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