JPS6410443B2 - - Google Patents
Info
- Publication number
- JPS6410443B2 JPS6410443B2 JP59012586A JP1258684A JPS6410443B2 JP S6410443 B2 JPS6410443 B2 JP S6410443B2 JP 59012586 A JP59012586 A JP 59012586A JP 1258684 A JP1258684 A JP 1258684A JP S6410443 B2 JPS6410443 B2 JP S6410443B2
- Authority
- JP
- Japan
- Prior art keywords
- adsorption
- gas
- adsorption tower
- stage
- purge
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 239000007789 gas Substances 0.000 claims description 209
- 238000001179 sorption measurement Methods 0.000 claims description 206
- 238000000034 method Methods 0.000 claims description 103
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 88
- 230000008569 process Effects 0.000 claims description 60
- 238000010926 purge Methods 0.000 claims description 59
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 44
- 239000001569 carbon dioxide Substances 0.000 claims description 44
- 239000003463 adsorbent Substances 0.000 claims description 39
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 37
- 239000002994 raw material Substances 0.000 claims description 31
- 229910002091 carbon monoxide Inorganic materials 0.000 claims description 26
- 238000011282 treatment Methods 0.000 claims description 23
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims description 19
- 229910052757 nitrogen Inorganic materials 0.000 claims description 17
- 238000011084 recovery Methods 0.000 claims description 17
- 239000002912 waste gas Substances 0.000 claims description 14
- 230000006837 decompression Effects 0.000 claims description 10
- 238000003795 desorption Methods 0.000 claims description 7
- 238000000926 separation method Methods 0.000 claims description 7
- 229910001873 dinitrogen Inorganic materials 0.000 claims description 4
- 239000000463 material Substances 0.000 claims description 4
- 239000000203 mixture Substances 0.000 description 7
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 5
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 4
- 229910021536 Zeolite Inorganic materials 0.000 description 4
- 239000001257 hydrogen Substances 0.000 description 4
- 229910052739 hydrogen Inorganic materials 0.000 description 4
- 238000009991 scouring Methods 0.000 description 4
- 239000010457 zeolite Substances 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 238000011017 operating method Methods 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 241000196324 Embryophyta Species 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 239000011819 refractory material Substances 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 241000007534 Acacia tetragonophylla Species 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 238000003723 Smelting Methods 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 239000012159 carrier gas Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000004817 gas chromatography Methods 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000011946 reduction process Methods 0.000 description 1
- 230000008929 regeneration Effects 0.000 description 1
- 238000011069 regeneration method Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02C—CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]
- Y02C20/00—Capture or disposal of greenhouse gases
- Y02C20/40—Capture or disposal of greenhouse gases of CO2
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/151—Reduction of greenhouse gas [GHG] emissions, e.g. CO2
Landscapes
- Industrial Gases (AREA)
- Separation Of Gases By Adsorption (AREA)
- Carbon And Carbon Compounds (AREA)
Description
本発明は圧力変動式吸着分離法（PSA法）に
よつて、少なくとも一酸化炭素、二酸化炭素、及
び窒素を含む原料ガス、例えば転炉又は高炉の排
ガスから高純度の一酸化炭素を安定して得る方法
に関する。製鉄所において精練容器から発生する
排ガスは比較的多量のCOガスを含有している。
その組成は転炉排ガス、高炉排ガスについては、
以下に示す範囲内にある。
The present invention uses a pressure swing adsorption separation method (PSA method) to stably extract high-purity carbon monoxide from a raw material gas containing at least carbon monoxide, carbon dioxide, and nitrogen, such as exhaust gas from a converter or blast furnace. Regarding how to get it. The exhaust gas generated from smelting vessels in steel plants contains a relatively large amount of CO gas.
The composition of converter exhaust gas and blast furnace exhaust gas are as follows:
Within the range shown below.
【表】
もし、これらの排ガスから高純度のCOガスを
安価に回収できれば、合成化学原料、精練容器内
溶融金属中への吸込みガスとしての用途が拓け
る。合成化学原料としてのCOガスを考える際に
は、合成反応が高温・高圧条件下に行なわれるの
が通例であることから、反応容器を損なわさせる
酸化性ガスの除去が必須であり、CO2濃度を出来
る限り低下させる必要がある。また反応効率を上
げるためには通常反応に関与しないN2も出来る
だけ除去するのが望ましい。一方、溶融金属の精
練の効率化を目的とする精練容器内へのガス吸込
み操作は広く用いられているが、溶融金属中の不
純ガス成分（窒素、水素など）の濃度上昇を嫌う
観点から高価なArガスが使用されるのが通例で
ある。製鉄所内で発生する転炉ガス、高炉ガスか
ら高純度COガスを安価に回収できれば、これを
Arに代替して吸込みガスとして使用することは
ほぼ可能である。この際、高純度COガス中の
N2、H2濃度は溶鉄の窒素濃度、水素濃度上昇を
防止するために低いのが望ましく、またCO2濃度
も精練容器内張り耐火物として汎用されている炭
素系耐火物の酸化損傷防止、或いは溶鉄中の酸素
濃度上昇防止の観点から低いのが望ましい。
従来、上記排ガスを原料に高純度COガスを回
収するプロセスとしては、深冷分離法によりN2、
H2、CO2を分離する方法、或いは、銅液法、
Cosorb用といつた、COを選択的に溶液に吸収さ
せた上で回収する方法が考えられてきた。しかし
ながら、前者においては低温と高圧を必要とし、
後者においては高温と高圧を必要とし、両者共に
設備が複雑かつ高価になる欠点がある。また深冷
分離法では、N2とCOの沸点が接近しているた
め、N2とCO2の分離を完全に行なうことも困難
である。
先に本出願人は、少なくともCO、CO2、N2を
含む原料ガス中からCOガスを安価な設備費と操
業費のもとに濃縮、分離する方法として圧力変動
式吸着分離法（PSA法）に関する発明を出願し
た。即ち、先願発明（特願昭58−110616号参照）
においては少なくともCO、CO2、N2を含む混合
ガス中からPSA法によりCOを回収するに際して
第１段階の吸着操作によりCO2を吸着除去し、第
２段階の吸着操作によりN2を除去することによ
り、高純度COガスを製品ガスとして回収する方
法を示したのであるが、この方法に基くシステム
を最適な条件のもとに操業する方法についての解
明は不十分なものであつた。即ち、本システムの
原料ガスとなる例えば転炉排ガスはその組成を
刻々と変化させているものであり、高純度COガ
スを回収する際に転炉ガスから除去すべき、N2、
CO2といつた不純ガス成分の量は変動している。
この前提下で回収する高純度COガスの純度を一
定レベル以上に保ちつつ、最も経済的に本システ
ムを操業する方法は全く未解明であつた。この点
について本発明者らは鋭意研究を重ねた結果、本
システムの最適な操業方法を解明するに至つたも
のである。本発明は二段階吸着操作により、少な
くとも一酸化炭素、二酸化炭素及び窒素を含有す
る原料ガス中の一酸化炭素を濃縮分離する方法に
おいて
(a) その第１段階の吸着操作は原料ガス中の二酸
化炭素に対して、選択吸着性を有する吸着物質
を収納した２つ以上の吸着塔を使用し、その方
法は各吸着塔で少なくとも吸着工程及びパージ
操作を含む脱着工程を繰り返す圧力変動式吸着
分離によつてその原料ガスから二酸化炭素を除
去することからなり、そして、
(b) 第２段階の吸着操作は、第１段階の吸着工程
から排出される二酸化炭素の除去されたガス
（以後第１段階製品ガスという）中の一酸化炭
素に対して選択性を有する吸着物質を充填した
２つ以上の吸着塔を使用し、その方法は、
() 第１段階製品ガスによる吸着塔の吸着工
程
() その吸着塔のパージ
() 製品ガスの脱着回収
から成る少なくとも３工程を繰り返すことから
なり、第２段階処理の吸着工程から排出される
廃棄ガスを第１段階処理における吸着塔再生の
パージ工程に使用し、そして、
(c) 原料ガス中の少なくとも二酸化炭素と窒素ガ
ス濃度を計測して、或いは、製品ガス中の少な
くとも二酸化炭素と窒素ガス濃度を計測して、
その結果に基づいて、次の三つの方法
() 第１段階処理のパージ工程で使用する減
圧排気機器の排気能力の制御
() 第２段階処理、吸着工程の廃棄ガス量の
制御
() 第２段階処理、パージ工程に使用するパ
ージガス量の制御
のうち、少なくとも一つの操作を行なうことによ
り、一酸化炭素の濃縮分離を行なうことを特徴と
した方法に関する。
以下に本発明の細部を説明する。
本発明は第１段階における、少なくとも一酸化
炭素、二酸化炭素、窒素を含む原料ガスから、圧
力変動式吸着分離法により二酸化炭素を除去する
工程は通常のPSA法、すなわち吸着、減圧、製
品ガスによるパージおよび製品ガスによる加圧の
繰返しにより実施しても良く、又少なくとも吸着
工程及びパージ操作を含む脱着工程を含む他の方
法であつても良い。該原料ガスから二酸化炭素を
除去する好ましい方法は次の通りである。
二酸化炭素に対して選択性を有する吸着物質を
充填した２つ以上の吸着塔を使用し、その方法は
() 第１段階製品ガスにより吸着塔を加圧する
加圧工程、好ましくは0.2〜3.0Kg/cm2Gまで加圧
する
() 原料ガスを吸着塔に流して主として二酸化
炭素を吸着させ、二酸化炭素の除去された第１
段階製品ガスを回収する吸着工程
() 次いで、吸着塔を大気圧附近まで減圧する
減圧工程
() 次いで、吸着塔を減圧排気機器により排気
する排気工程（好ましくは、破棄は300Torr〜
30Torrまで行なわれる）、そして、
() 第２段階吸着()工程からの廃棄ガスを排
気工程の終つた吸着塔に導入しつつ減圧排気機
器による排気を行なうパージ工程から成り、定
期的に吸着塔間のガスの流れを変えて上記操作
を繰返すことからなる方法である。
本発明の第１段階処理の目的は二酸化炭素の吸
着除去であるが、二酸化炭素の吸着剤に対する吸
着能が大きいので、二酸化炭素を吸着除去した製
品ガスを回収する吸着工程に困難は少ない。しか
し、逆に吸着塔を減圧させ、次いで排気する工程
で吸着剤に吸着している二酸化炭素を脱着させ、
吸着塔外に排出させる工程をスムーズに行なう際
に困難が伴う。即ち、吸着剤から脱着した二酸化
炭素が再吸着して容易には吸着塔外に排出されぬ
事態が生じやすい。脱着した二酸化炭素の吸着塔
外への排出を助けるために搬送ガスとしてパージ
ガスの導入を行なう方法は、通常のPSA法でも
採用されているものであるが、本発明の方法にお
いては、パージガスの導入を減圧排気条件下に行
ないパージガス容積を大としたところに特徴を有
すると共に、通常のPSA法では製品ガスをパー
ジガスとして使用し、その結果として、製品ガス
回収率の低下を余儀なくされていたものを、本発
明では、二段階吸着法の特徴を生かして、後述す
る第２段階処理の吸着工程から排出される不用の
廃棄ガスをパージガスに利用する合理性も併せ持
つている。この特徴を有するパージ工程の採用に
より、吸着剤からの二酸化炭素の脱着をスムーズ
に行なうことが可能となり、その結果として次の
吸着工程における二酸化炭素の吸着除去が支障な
く行なえるようになつた。このパージ工程の操業
方法と、二酸化炭素の吸着除去効率との関係を詳
細に検討したところ、第１図に示す関係が求めら
れ、これが、二酸化炭素の吸着除去をスムーズに
行なうための操業指針たり得ることを本発明者ら
は確認したわけである。第１図は吸着塔内に充填
されている吸着剤単位重量当りに１サイクルの吸
着工程で吸着し得る二酸化炭素の量が、パージ工
程のパージガス容積と共に増大している関係を示
す。即ち、パージガス容積の増大と共に、二酸化
炭素の吸着剤からの脱着効率が上昇し、従つて次
の吸着工程における二酸化炭素の吸着が可能とな
る吸着サイトが増す関係を発見したものである。
従つて、原料ガス流量、原料ガス中の二酸化炭素
ガス濃度の計測値から求まる吸着させるべき二酸
化炭素に対応するパージガス容積を図１により定
めれば安定した二酸化炭素吸着除去が可能とな
る。パージガス容積の制御は第２段階処理から廃
棄されるガスの導入量制御によつて行なつても良
いが、減圧排気機器に排気能力の制御によつても
良い。即ち、排気能力を上げればガス容積を上昇
させることが可能である。減圧排気機器に要する
動力の削減は本システムの操業に要求される重要
なポイントであり、図１の関係を基にこの動力を
必要最小限に制御する方法は極めて重要な技術と
いえる。
本発明の第２段階の吸着操作は、第１段階の吸
着工程から排出された第１段階製品ガス中の一酸
化炭素に対して選択性を有する吸着物質、例えば
天然ゼオライト、改質ゼオライト又は合成ゼオラ
イト等を充填した２つ以上の吸着塔を使用し、そ
の好ましい方法は
() 第１段階製品ガスにより吸着塔を加圧する
加圧工程
() さらに第１段階製品ガスを吸着塔に流し
て、吸着塔出口におけるガス中の易吸着成分
（一酸化炭素）の濃度が、吸着塔入口における
ガス中の易吸着成分の濃度に達するまで、或い
は達した後適当な量又は時間の間、第１段階製
品ガスと流し続けるか、もしくは両者の濃度が
等しくなる点の少し前まで第１段階製品ガスを
流して、吸着剤に易吸着成分を吸着させる吸着
（）工程。この工程で吸着塔から排出されるガ
スは、前記第１段階()のパージ工程のパージ
ガスとして使用される。
() 吸着()工程終了後、その吸着塔を吸着圧
力と大気圧との間の任意圧力まで減圧する工
程、
() 減圧工程終了後、その吸着塔と排気脱着が
終つた吸着塔を連結し、前者の吸着塔から後者
の吸着塔に前者のガスを導入し、前者の吸着塔
の圧力を大気圧又は大気圧近くまで降下させる
減圧放圧工程。この際、両者の吸着塔の圧力を
ほぼ均圧させても良い。また、前者の吸着塔の
圧力を降下させる際に放出されるガスを系外に
放出してしまい、後者の吸着塔に導入しない方
法を取つても良い。
() 次いで、減圧した吸着塔に製品ガスを導入
して難吸着成分をパージするパージ工程。本工
程で吸着塔から排出されるガスを後記する吸着
（）工程を終つた吸着塔に導入する工程は任意
である。
() パージ工程を終つた吸着塔を大気圧以下に
排気して、吸着剤に吸着されている易吸着成分
を脱着させ、製品ガスとして回収する回収工
程。
() 製品ガス回収が終つた吸着塔と吸着()工
程を終つた吸着塔を連結し、後者の吸着塔から
の減圧放圧ガスを前者の吸着塔に導入し、吸着
剤に易吸着成分を吸着させる吸着()工程。
() 次いで、吸着()工程を終つた吸着塔と減
圧放圧工程の終つた吸着塔を連結し、後者の吸
着塔のパージ工程から排出されるガスを前者の
吸着塔に導入し、吸着剤に易吸着成分を吸着さ
せる吸着()工程、
から成り、定期的に吸着塔間のガスの流れを変え
て、上記の操作を繰返すことを特徴とした方法で
ある。尚、工程()、()はそれぞれ工程()、
（）の方法に従つて定まるものであり、その実施
は任意となる。
本発明の第２段階工程()は吸着塔に第１段階
製品ガスを導入する吸着塔の加圧工程である。本
段階で回収すべきガスは易吸着成分であるので高
い吸着圧は必要でなく、３Kg/cm2G程度の吸着圧
で十分であり、それより低い吸着圧であつても良
い。
工程()は吸着()工程であり、第１段階製品
ガス中の易吸着成分を吸着剤に吸着させる工程で
ある。吸着塔出口におけるガス中の易吸着成分の
濃度が吸着塔入口におけるガス中のそれに等しく
なつた点というのは、吸着剤の破過の終了を意味
する。回収すべき成分が易吸着成分であり、所定
の吸着剤量のもとで十分に多くの製品ガス量を回
収したり、純度の良い製品ガスを回収するために
は、破過終了或いは破過終了後においてもなおか
つ吸着剤に残存する吸着サイトに易吸着成分を吸
着させることが必要であり、破過終了後も一定量
の第１段階製品ガスを流すか、又は一定時間の間
第１段階製品ガスを流すことを要する。或いは、
破過終了に達する少し前まで吸着を行なうにとど
めても製品ガス純度の点から問題の少ない場合も
ある。
この吸着()工程を吸着剤の破過の前後のどの
水準迄継続するには製品ガスの純度を定める上で
重要であるので、この点の検討を詳細に行なつ
た。本発明の第１段階製品ガス中の易吸着成分は
一酸化炭素であり、難吸着成分は窒素である。破
過終了以前においては難吸着成分である窒素も吸
着剤に共吸着しており、このまま脱着させ製品ガ
スとして回収した場合には製品純度の低下は避け
難い。但し、難吸着成分の共吸着の度合は、第１
段階製品ガスの組成に依存するものであり、難吸
着成分の少ないガスを吸着()工程に導入する場
合に於いては、破過終了前に吸着()工程を終つ
ても良いことになる。吸着()工程を破過終了後
も過大に継続することは易吸着成分を多量に廃棄
することになり、望ましいことではない。従つ
て、製品ガス純度を一定に維持しつつ、かつ、易
吸着成分の廃棄量を最少限にとどめる吸着()工
程の制御が望まれる。検討すると吸着()工程を
破過終了以前あるいは破過終了後のどの水準で終
らせるかを決定する指針が望まれるわけである。
この点の検討結果が図２に示すものである。図
２は、第２段階処理の前後でガス中の難吸着成分
濃度の比率が、吸着()工程で１サイクル当り単
位吸着剤重量当りの廃棄ガス量によつて変化をす
る関係を示す。第１段階製品ガス中の難吸着成分
濃度が増した場合には廃棄ガス量を増加させるこ
とにより製品ガス中の難吸着成分濃度の絶対値を
一定に維持するのが可能となる。従つて第１段階
製品ガス中の難吸着成分濃度を計測しつつ、一定
の製品ガス純度を維持するのは必要最低限の吸着
（）工程廃棄ガス量を図２より求めて、易吸着成
分の回収を最大にもつて行く操業が可能といえる
わけであり、これも重要な技術である。
工程()は、吸着工程終了後、吸着圧と大気圧
との間の任意の圧力ほぼ大気圧まで好ましくは並
流方向に減圧して吸着塔の出口附近に残留してい
る難吸着成分を廃棄する。この工程は必ずしも行
なわなくても良い。
工程()は吸着()工程が終つた吸着塔内の圧
力を減少させ、吸着剤と吸着剤の空隙に存在する
難吸着成分に富んだガスを該吸着塔外に放出する
ために行なうものである。この操作は該吸着塔圧
力を大気圧まで減少させるか、または大気圧以上
の適当な圧力で中止するか、もしくは大気圧以下
で製品ガス回収を終つ他の吸着塔に均圧させるま
で低下させても良い。尚、製品ガス回収の終つた
吸着塔への減圧ガスの導入は任意である。
工程()は減圧した吸着塔に製品ガスを導入し
て、吸着剤間の空隙になお残存している難吸着成
分をパージする。この場合の製品ガスの導入圧は
吸着圧より低く、大気圧より高い方が望ましい。
この工程に使用するパージガスの量はこの工程に
引き続く製品ガス回収工程で回収される製品ガス
純度に大きな変化を与えるので、適切に制御しな
ければならない。即ち、パージガス量が過少であ
れば吸着剤間空隙にある難吸着成分の吸着塔外へ
の放出が不十分であり、引き続いて回収される製
品ガス中に難吸着成分が共在することになり、製
品ガス純度の向上は望めない。但し、製品ガスを
余りに多量にパージガスとして還流させてしまう
と、製品ガス純度の向上はあるものの、製品とし
て使用し得る製品ガス量が低下してしまう不利益
が伴う。従つて、パージガス量を場合に応じて最
適に制御し、製品ガス純度と製品ガス量の確保を
はかる方法の確立が望まれる。この点について詳
細な検討を行なつたところ、図３に示す関係が得
られた。
即ち、難吸着成分の第２段階処理における除去
率はパージ工程に使用するパージガス量と共に向
上する関係である。従つて、第２段階処理に供さ
れる第１段階製品ガス中の難吸着成分濃度が低い
場合には、難吸着成分除去率の低いパージ操作、
即ちパージガス量を低下させても、一定の製品ガ
ス純度を確保確保でることが、図３の関係からい
える。従つて、第２段階処理に供する原料ガスで
ある第１段階製品ガス中の難吸着成分濃度を実測
するか、或いは原料ガス中のその濃度と、第１段
階処理の二酸化炭素除去の効率から予測される第
１段階製品ガス中難吸着成分濃度の推定値に基
き、所要の製品ガス純度を参照して、難吸着成分
除去率を決定し、それに必要なパージガス量を決
定し、制御する方法を採用することにより、製品
ガス純度の確保と、製品ガス回収量の最大値の確
保を同時に達成できることになる。
尚、本パージ工程において、吸着塔から排出さ
れるガスは、製品ガスに吸着剤間空隙の難吸着成
分に富むガスが加わつたものであり、十分に易吸
着成分に富む組成のガスであり、製品ガス回収、
あるいは減圧ガスの回収である吸着()工程を終
つた他の吸着塔に導入して、易吸着成分の吸着回
収をはかるのが望ましいが、系外に廃棄してもか
まわない。
工程()はパージ工程が終つた吸着塔を減圧排
気装置を用いて、300Torr以下、好ましくは300
〜30Torrまで減圧し、吸着剤に吸着されていた
成分を脱着させ製品ガスとして回収する。
工程()は製品ガス回収が終つた吸着塔と吸着
（）工程を終つた吸着塔を連結し、後者の吸着塔
からの減圧方圧ガスを前者の吸着塔に導入し、吸
着剤に易吸着成分を吸着させる吸着()工程。
工程()は、吸着()工程を終つた吸着塔と減
圧放圧工程の終つた吸着塔とを連結し、後者の吸
着塔のパージ工程から排出されるガスを前者の吸
着塔に導入し、吸着剤に易吸着成分を吸着させる
吸着()工程である。この工程()は任意である。
以下、本発明の代表的な具体例である転炉排ガ
ス中の二酸化炭素をまず除去し、次いで、窒素、
水素を除去して一酸化炭素を分離回収する方法に
基いて本発明を詳しく説明するが、本発明の方法
はこれらの具体例に限定されるものではない。
第４図は、吸着サイクルにより連続的に転炉排
ガスから一酸化炭素を分離回収するシステムのフ
ローシートであり、第５図は第４図のシステムの
制御系の概念を示すフローシートである。第５図
で、G.Hはそれぞれ第１段階、第２段階処理装置
を代表する。
まず、第４図に基いて、吸着操作を説明する。
吸着塔Ａ，Ｂには二酸化炭素を選択的に吸着する
吸着剤が収納されている。吸着塔Ａはパージ工程
を終りバルブ１〜６は閉の状態にありかつ、吸着
塔圧力は300Torr以下、好ましくは30Torr迄減
圧されている。一方吸着塔Ｂは吸着工程を終り、
減圧工程に採るべく、バルブ４〜１２が全て閉の
状態からバルブ９のみ開の状態に移る。この状態
を基準に吸着塔Ａに着目して、吸着のサイクルを
例示すると次のようになる。まず、吸着塔Ａに第
１段階製品ガスを導入するためにバルブ６を開
く。吸着塔Ａの圧力が、0.01〜3.0Kg/cm2G、好ま
しくは、0.2Kg〜1.0Kg/cm2Gの吸着圧力に達した
ら、バルブ６を閉じ、バルブ１，２を開にして前
記吸着圧力を維持するように原料ガスを吸着塔Ａ
に流す。一定時間、一定原料ガス量の吸着工程終
了後バルブ１，２は閉じ、次いでバルブ３を開い
て、吸着塔の塔内圧力を大気圧附近まで減圧方圧
させる。吸着塔Ａの圧力が大気圧附近に達すると
バルブ３を閉じ、次いでバルブ４を開にして、真
空ポンプ４０を用いて、減圧排気を行ない、吸着
剤に吸着している二酸化炭素を脱着させる。この
際の排気圧力が300Torr以下、好ましくは
30Torrになる迄排気を行ない、次いでバルブ５
を開いて、第２段階処理装置からの廃棄ガスを減
圧下に導入するパージ工程を行なう。パージ工程
が終了するとバルブ４，５は閉となる。次の工程
は最初にもどり、バルブ６を開くことになる。
上記操作を吸着塔Ａ，Ｂのそれぞれにおいて順
次繰返すことによつて連続的に吸着剤に二酸化炭
素を吸着させ除去しようとするものである。第１
段階処理において、吸着塔Ａ，Ｂの塔上から流出
する二酸化炭素が除去された第１段階製品ガスは
第２段階処理装置に導入され、ここで水素、窒素
が除去され、高濃度に濃縮された一酸化炭素ガス
として回収される。吸着塔Ｃ，Ｄ，Ｅ，Ｆには易
吸着成分（一酸化炭素）を選択的に吸着する吸着
剤が収納されている。吸着塔ＣとＤに着目して、
吸着工程を説明する。吸着塔Ｃが吸着()工程、
吸着塔Ｄが製品ガス回収工程に有る状況を基準に
とる。このとき、バルブ１８，１７が閉となり第
１段階製品ガスが吸着塔Ｃに流れており、一方、
バルブ２７は開となつて吸着塔Ｄの吸着剤に吸着
している易吸着成分の脱着・製品ガスとしての回
収が行なわれている。吸着塔Ｃの吸着圧力は、第
１段階製品ガスの圧力によりおのずから定まる
が、0.01〜3.0Kg/cm2G、好ましくは0.2〜1.0Kg/cm2
Ｇが適当である。一方吸着塔Ｄの製品ガス回収工
程は吸着塔圧力300Torr以下、好ましくは
30Torrまで維持するのが望ましい。
一定時間、或いは一定ガス量を吸着塔Ｃに流
し、一酸化炭素を吸着剤に吸着させる吸着()工
程終了後、バルブ１８，１７を閉じ、同時にバル
ブ２７を閉じて吸着塔Ｄの製品ガス回収工程を終
る。次いで、吸着塔ＣとＤの連結パイプにあるバ
ルブ１９を開き、吸着塔Ｃの塔内圧力を大気圧附
近まで減圧する。このとき放出されたガスは、吸
着塔Ｄに導入され、易吸着成分を吸着剤に吸着さ
せる（吸着()工程）。吸着塔Ｃの塔内圧力が大
気圧附近になるとバルブ２０を開いて製品ガスタ
ンク４２より製品ガスを吸着塔Ｃに導入し、吸着
剤間の空隙に存在する難吸着成分ガスを追い出す
パージ工程を行なう。この際吸着塔Ｃの塔上から
流出するガスはバルブ１９を介して吸着塔Ｄに導
入され、易吸着成分が吸着剤に吸着される（吸着
（）工程）。パージ工程が終了すると、バルブ１
９，２０は閉じられ、バルブ２１及びバルブ２２
を開とする。この操作により吸着塔Ｃは減圧排気
機器４１を用いて減圧下の製品ガス回収工程に移
り、一方吸着塔Ｄは吸着()工程、吸着()工程
に引き続く、第１段階製品ガスによる加圧工程に
入る。加圧工程により吸着塔Ｄの塔内圧力が吸着
圧力に達したならば、バルブ２３を開き、吸着塔
Ｄは吸着()工程に移る。以上の操作が、吸着塔
ＣとＤが役割りを変えてはいるが基準の状況に帰
る迄の工程である。この操作を順次繰り返すこと
によつて連続的に吸着剤に易吸着成分である一酸
化炭素ガスを吸着させて、分離精製することが出
来る。尚、吸着塔Ｅ，ＦもＣ，Ｄと同様の工程を
繰り返すものである。
次に、第５図に基き、本システムの最適な操業
方法を示す。原料ガス中の二酸化炭素、窒素濃度
は分析計４５、第１段階製品ガス中のそれは分析
計４６、製品ガス中のそれは分析計４７によりそ
れぞれ連続的に測定されている。分析計はガスク
ロマトグラフイー、赤外線吸収計などを使用出来
る。これらの分析信号は流量計（図示せず）信号
と共に計算機４４に伝送される。第１段階処理に
おける二酸化炭素除去を最も効率的に行なう為の
制御は次のように行なう。分析計４５の二酸化炭
素濃度信号と原料ガス流量信号に基き、吸着させ
るべき、二酸化炭素量を計算機４４で演算し、第
１図の関係より所要のパージガス容積を求める。
次いで、パージに供しうる第２段階廃棄ガス量を
流量信号に基いて定め、所要のパージガス容積と
するに必要な、減圧排気機器４０の排気能力を算
出する。減圧排気機器４０が、例えば電圧、周波
数可変電動機によるものであれば、所要の排気能
力に見合う計算機信号の伝送制御は極めて容易で
あり、また減圧排気機器を複数個直列ないしは量
列に設置しておいて、必要に応じて個々の機器の
駆動、停止を支持するシステムでも良い。これら
の操作により、原料ガス中の二酸化炭素濃度が高
くなつた際でも排気能力を上げることにより二酸
化炭素除去を確実に行なうことを可能とし、逆に
原料ガス中の二酸化炭素濃度が低下した際には排
気能力を低下を計ることによりシステムの操業動
力コストの削減を達成するのが可能となる。
次に第２段階処理における難吸着成分、特に窒
素の一酸化炭素からの分離を効率的に行なう方法
を説明する。分析計４６により第１段階製品ガス
中窒素濃度（分析計４５による原料ガス中窒素濃
度を基に、計算機４４で推算した濃度でも良い）
と、所定の製品ガス純度から定まる難吸着成分除
去率を計算し、図２、あるいは図３の関係から、
所要の吸着()工程廃棄ガス量あるいはパージ工
程に使用する製品ガス量を決定する操作を計算機
４４で行なう。これに基き、吸着()工程の廃棄
ガス量を調整する流量調節弁１４の開度制御、あ
るいは、パージガス量を調整する流量調節弁４３
の開度制御を行なうものである。以上の操作の一
つ、あるいは二つを同時に行なうことにより、原
料ガス中の窒素濃度が高い場合でも流量制御弁１
４、あるいは／及び４３の開度を上げることによ
り窒素除去率を向上させることで製品ガス純度を
一定に保ち得、また逆に原料ガス中の窒素濃度が
低い場合には、廃棄ガス量の低減、パージガス量
の低減のアクシヨンにより当システムの製品ガス
回収率及び回収量を向上を達成できることにな
る。
以上の説明では原料ガス濃度信号に基く、フイ
ードフオワード制御の例を示したが、分析計４７
の製品ガス濃度信号に基き、図１〜図３の関係よ
りフイードバツク制御するシステムも同様に有効
である。
尚、第１段階、第２段階処理の吸着塔に使用す
る吸着剤としては活性炭、活性アルミナ、合成ま
たは天然（改質したものも含む）ゼオライトなど
が適合する。
実施例
本発明の効果を説明するために、実施例を説明
する。第６図は、第４図、第５図のフローシート
に示した機能を有するシステムにより転炉排ガス
を原料に、製品ガス回収を行なつた際の原料ガス
及び製品ガス中のN2、CO2濃度を連続測定した
結果である。実施例（）は、第５図に示す動的
な制御系を使用せず、最初の原料ガス組成に対し
て適当な第１段階減圧排気機器能力の設定、及び
第２段階処理の吸着工程廃棄ガス量、パージ工程
パージガス量設定を行なつたまま連続操業した結
果である。所要の99％CO純度の製品ガス回収は
ほぼ達成されているものの、原料ガス組成によつ
ては純度が悪化し、98％CO程度になつている場
合もある。
一方、実施例（）は、原料ガス組成に応じ
て、第５図の制御ループに従う制御を行なつた結
果であり、安定して99％COの製品ガスの回収が
行なわれている。[Table] If high-purity CO gas could be recovered at low cost from these exhaust gases, it could be used as a raw material for synthetic chemicals or as a suction gas into the molten metal in the scouring vessel. When considering CO gas as a raw material for synthetic chemicals, since synthesis reactions are usually carried out under high temperature and high pressure conditions, it is essential to remove oxidizing gases that would damage the reaction vessel, and the CO 2 concentration need to be reduced as much as possible. Furthermore, in order to increase reaction efficiency, it is desirable to remove as much N2 as possible, which normally does not participate in the reaction. On the other hand, the gas suction operation into the scouring vessel is widely used to improve the efficiency of scouring molten metal, but it is expensive due to the risk of increasing the concentration of impure gas components (nitrogen, hydrogen, etc.) in the molten metal. Usually, Ar gas is used. If high-purity CO gas could be recovered at low cost from converter gas and blast furnace gas generated in steel plants, it would be possible to recover
It is almost possible to use it as a suction gas in place of Ar. At this time, in high purity CO gas
It is desirable that the N 2 and H 2 concentrations are low in order to prevent an increase in the nitrogen and hydrogen concentrations of molten iron, and the CO 2 concentration is also desirable to prevent oxidation damage to carbon-based refractories, which are commonly used as scouring container lining refractories. A low value is desirable from the viewpoint of preventing an increase in oxygen concentration in molten iron. Conventionally, the process of recovering high-purity CO gas using the above-mentioned exhaust gas as raw material has been to collect N 2 ,
A method of separating H 2 and CO 2 , or a copper liquid method,
Methods such as those for Cosorb have been considered in which CO is selectively absorbed into a solution and then recovered. However, the former requires low temperature and high pressure;
The latter requires high temperature and pressure, and both have the disadvantage of making the equipment complex and expensive. Furthermore, in the cryogenic separation method, it is difficult to completely separate N 2 and CO 2 because the boiling points of N 2 and CO are close to each other. The applicant previously proposed a pressure swing adsorption separation method (PSA method) as a method for concentrating and separating CO gas from a raw material gas containing at least CO, CO 2 and N 2 at low equipment and operating costs. ) has been filed for an invention. In other words, the prior invention (see Japanese Patent Application No. 110616/1983)
When recovering CO from a mixed gas containing at least CO, CO 2 and N 2 by the PSA method, CO 2 is adsorbed and removed in the first stage adsorption operation, and N 2 is removed in the second stage adsorption operation. This demonstrated a method for recovering high-purity CO gas as a product gas, but the method for operating a system based on this method under optimal conditions was not fully understood. In other words, the composition of the converter exhaust gas, which is the raw material gas for this system, is constantly changing, and when recovering high-purity CO gas, N 2 ,
The amount of impure gas components such as CO 2 fluctuates.
Under this premise, it was completely unclear how to operate this system most economically while maintaining the purity of the high-purity CO gas recovered above a certain level. As a result of extensive research into this point, the present inventors have come to discover the optimal operating method for this system. The present invention provides a method for concentrating and separating carbon monoxide in a raw material gas containing at least carbon monoxide, carbon dioxide, and nitrogen by a two-stage adsorption operation. The method uses two or more adsorption towers containing adsorbent substances that have selective adsorption properties for carbon, and the method is a pressure fluctuation type adsorption separation in which at least an adsorption step and a desorption step including a purge operation are repeated in each adsorption tower. (b) The second stage adsorption operation consists of the removal of carbon dioxide from the first stage adsorption process (hereinafter referred to as the first stage adsorption process). The method uses two or more adsorption towers filled with an adsorption material that is selective for carbon monoxide in the product gas (referred to as product gas), and the method includes () an adsorption step of the adsorption tower with the first stage product gas () Purging of the adsorption tower () It consists of repeating at least three steps consisting of desorption and recovery of product gas, and the waste gas discharged from the adsorption step of the second stage treatment is used in the purge step of the adsorption tower regeneration in the first stage treatment. and (c) measuring at least the carbon dioxide and nitrogen gas concentrations in the raw material gas, or measuring at least the carbon dioxide and nitrogen gas concentrations in the product gas,
Based on the results, the following three methods () Control the exhaust capacity of the decompression exhaust equipment used in the purge process of the first stage treatment () Control the amount of waste gas in the second stage treatment and adsorption process () Second The present invention relates to a method characterized in that carbon monoxide is concentrated and separated by performing at least one of stepwise treatment and control of the amount of purge gas used in a purge step. The details of the invention will be explained below. The present invention is characterized in that the first step of removing carbon dioxide from a raw material gas containing at least carbon monoxide, carbon dioxide, and nitrogen by a pressure fluctuation adsorption separation method is performed using the normal PSA method, that is, adsorption, depressurization, and product gas. It may be carried out by repeating purge and pressurization with product gas, or other methods including at least an adsorption step and a desorption step including a purge operation may be used. A preferred method for removing carbon dioxide from the raw material gas is as follows. Two or more adsorption towers filled with adsorption material having selectivity for carbon dioxide are used, and the method includes () a pressurization step of pressurizing the adsorption tower with the first stage product gas, preferably 0.2 to 3.0 Kg; Pressurize to /cm 2 G () The raw material gas is passed through an adsorption tower to mainly adsorb carbon dioxide, and the first
An adsorption step () to recover the staged product gas, then a depressurization step () to reduce the pressure in the adsorption tower to near atmospheric pressure, and an exhaust step (2) to exhaust the adsorption tower with a vacuum evacuation device (preferably, the disposal temperature is 300 Torr or more).
30 Torr), and () consists of a purge process in which the waste gas from the second stage adsorption () process is introduced into the adsorption tower after the evacuation process and is evacuated using a decompression exhaust equipment, and the adsorption tower is periodically This method consists of repeating the above operation by changing the flow of gas between the two. The purpose of the first stage treatment of the present invention is to adsorb and remove carbon dioxide, and since the adsorption capacity of carbon dioxide to the adsorbent is large, there are few difficulties in the adsorption step of recovering the product gas from which carbon dioxide has been adsorbed and removed. However, in the process of reducing the pressure in the adsorption tower and then exhausting it, the carbon dioxide adsorbed on the adsorbent is desorbed.
Difficulties arise in smoothly carrying out the process of discharging the adsorbent to the outside of the adsorption tower. That is, the carbon dioxide desorbed from the adsorbent is likely to be re-adsorbed and not easily discharged outside the adsorption tower. The method of introducing purge gas as a carrier gas to help discharge the desorbed carbon dioxide to the outside of the adsorption tower is also adopted in the normal PSA method, but in the method of the present invention, the introduction of purge gas is It is characterized by the fact that it is carried out under reduced pressure exhaust conditions and the purge gas volume is increased, and the product gas is used as the purge gas in the normal PSA method, which results in a reduction in the product gas recovery rate. In the present invention, by taking advantage of the characteristics of the two-stage adsorption method, it also has the rationality of utilizing the unnecessary waste gas discharged from the adsorption step of the second stage treatment, which will be described later, as the purge gas. By adopting a purge step having this feature, it has become possible to smoothly desorb carbon dioxide from the adsorbent, and as a result, it has become possible to adsorb and remove carbon dioxide in the next adsorption step without any problems. After a detailed study of the relationship between the operating method of this purge process and the adsorption and removal efficiency of carbon dioxide, the relationship shown in Figure 1 was obtained, and this can be used as an operational guideline for smooth adsorption and removal of carbon dioxide. The present inventors have confirmed that it can be obtained. FIG. 1 shows a relationship in which the amount of carbon dioxide that can be adsorbed in one cycle of adsorption process per unit weight of adsorbent packed in the adsorption tower increases with the purge gas volume in the purge process. That is, we discovered a relationship in which as the purge gas volume increases, the desorption efficiency of carbon dioxide from the adsorbent increases, and therefore the number of adsorption sites that can adsorb carbon dioxide in the next adsorption step increases.
Therefore, if the purge gas volume corresponding to the carbon dioxide to be adsorbed, which is determined from the raw material gas flow rate and the measured value of the carbon dioxide gas concentration in the raw material gas, is determined from FIG. 1, stable carbon dioxide adsorption and removal becomes possible. The purge gas volume may be controlled by controlling the amount of gas discarded from the second stage treatment, but may also be controlled by controlling the exhaust capacity of the decompression exhaust equipment. That is, by increasing the exhaust capacity, it is possible to increase the gas volume. Reducing the power required for the decompression exhaust equipment is an important point required for the operation of this system, and the method of controlling this power to the necessary minimum based on the relationship shown in Figure 1 can be said to be an extremely important technology. The second stage adsorption operation of the present invention is performed using an adsorbent material that is selective for carbon monoxide in the first stage product gas discharged from the first stage adsorption process, such as natural zeolite, modified zeolite or synthetic zeolite. A preferred method for using two or more adsorption towers filled with zeolite etc. is () pressurizing the adsorption tower with the first stage product gas () further flowing the first stage product gas into the adsorption tower, The first step is continued until the concentration of the easily adsorbed component (carbon monoxide) in the gas at the outlet of the adsorption tower reaches the concentration of the easily adsorbed component in the gas at the inlet of the adsorption tower, or for an appropriate amount or time after reaching the concentration of the easily adsorbed component in the gas at the inlet of the adsorption tower. An adsorption () step in which the first stage product gas is allowed to continue to flow with the product gas, or is allowed to flow until just before the concentration of both becomes equal, allowing the adsorbent to adsorb easily adsorbable components. The gas discharged from the adsorption tower in this step is used as a purge gas in the purge step of the first stage (). () After the adsorption () process is completed, the adsorption tower is depressurized to an arbitrary pressure between the adsorption pressure and atmospheric pressure. () After the depressurization process is completed, the adsorption tower is connected to the adsorption tower that has completed exhaust desorption. , a depressurization and release step in which the former gas is introduced from the former adsorption tower to the latter adsorption tower, and the pressure of the former adsorption tower is lowered to atmospheric pressure or near atmospheric pressure. At this time, the pressures of both adsorption towers may be approximately equalized. Alternatively, a method may be adopted in which the gas released when the pressure of the former adsorption tower is lowered is released outside the system and is not introduced into the latter adsorption tower. () Next, a purge step in which the product gas is introduced into the depressurized adsorption tower to purge difficult-to-adsorb components. The step of introducing the gas discharged from the adsorption tower in this step into the adsorption tower that has completed the adsorption () step described later is optional. () A recovery process in which the adsorption tower that has completed the purge process is evacuated to below atmospheric pressure, the easily adsorbed components adsorbed by the adsorbent are desorbed, and the gas is recovered as a product gas. () The adsorption tower that has completed the product gas recovery and the adsorption tower that has completed the adsorption () process are connected, and the depressurized and released gas from the latter adsorption tower is introduced into the former adsorption tower to add easily adsorbable components to the adsorbent. Adsorption () process to adsorb. () Next, the adsorption tower that has completed the adsorption () process and the adsorption tower that has completed the depressurization and release process are connected, and the gas discharged from the purge process of the latter adsorption tower is introduced into the former adsorption tower, and the adsorption tower is This method is characterized by repeating the above operation by periodically changing the gas flow between the adsorption towers. In addition, processes () and () are respectively processes () and
It is determined according to the method in (), and its implementation is optional. The second stage process () of the present invention is an adsorption tower pressurization process in which the first stage product gas is introduced into the adsorption tower. Since the gas to be recovered at this stage is a component that is easily adsorbed, a high adsorption pressure is not necessary, and an adsorption pressure of about 3 kg/cm 2 G is sufficient, and a lower adsorption pressure may be used. Step () is an adsorption () step, which is a step in which easily adsorbable components in the first stage product gas are adsorbed onto an adsorbent. The point at which the concentration of easily adsorbable components in the gas at the outlet of the adsorption tower becomes equal to that in the gas at the inlet of the adsorption tower means the end of breakthrough of the adsorbent. The components to be recovered are easily adsorbed components, and in order to recover a sufficiently large amount of product gas or to recover product gas with good purity under a predetermined amount of adsorbent, it is necessary to It is necessary to adsorb easily adsorbable components to the adsorption sites remaining in the adsorbent even after the completion of breakthrough. Requires flow of product gas. Or,
Even if adsorption is performed until just before reaching the end of breakthrough, there may be little problem in terms of product gas purity. Since it is important to determine the purity of the product gas that this adsorption process is continued to any level before or after the adsorbent breakthrough, this point was studied in detail. The easily adsorbed component in the first stage product gas of the present invention is carbon monoxide, and the poorly adsorbed component is nitrogen. Before the completion of breakthrough, nitrogen, which is a difficult-to-adsorb component, is also co-adsorbed on the adsorbent, and if it is desorbed and recovered as a product gas, a decrease in product purity is unavoidable. However, the degree of co-adsorption of difficult-to-adsorb components is
This depends on the composition of the staged product gas, and if a gas containing few difficult-to-adsorb components is introduced into the adsorption () step, the adsorption () step may be completed before the breakthrough is completed. Continuing the adsorption () step for an excessively long time after the breakthrough is undesirable because a large amount of easily adsorbable components will be discarded. Therefore, it is desired to control the adsorption process in a way that maintains the product gas purity constant and minimizes the amount of easily adsorbed components that are discarded. Considering this, it is desirable to have a guideline for determining at what level the adsorption process should be completed before or after the breakthrough. The results of this study are shown in Figure 2. FIG. 2 shows the relationship in which the ratio of the concentration of poorly adsorbed components in the gas before and after the second stage treatment changes depending on the amount of waste gas per unit adsorbent weight per cycle in the adsorption ( ) process. When the concentration of the poorly adsorbed component in the first stage product gas increases, the absolute value of the concentration of the poorly adsorbed component in the product gas can be maintained constant by increasing the amount of waste gas. Therefore, in order to maintain a constant product gas purity while measuring the concentration of poorly adsorbed components in the first stage product gas, the minimum amount of adsorption () process waste gas is determined from Figure 2, and the amount of easily adsorbed components is determined. It can be said that operations that maximize recovery are possible, and this is also an important technology. In step (), after the adsorption step is completed, the pressure is reduced to an arbitrary pressure between the adsorption pressure and atmospheric pressure, preferably in the parallel flow direction, and the difficult-to-adsorb components remaining near the outlet of the adsorption tower are discarded. do. This step does not necessarily have to be performed. Step () is carried out to reduce the pressure inside the adsorption tower after the adsorption () step and release gas rich in difficult-to-adsorb components existing in the gap between the adsorbent and the adsorbent to the outside of the adsorption tower. be. This operation is performed by reducing the adsorption tower pressure to atmospheric pressure, or stopping at a suitable pressure above atmospheric pressure, or reducing the pressure to equalization in another adsorption tower terminating product gas recovery below atmospheric pressure. It's okay. Note that the introduction of reduced pressure gas into the adsorption tower after product gas recovery is optional. In step (), the product gas is introduced into the adsorption tower under reduced pressure to purge difficult-to-adsorb components still remaining in the voids between the adsorbents. In this case, the introduction pressure of the product gas is preferably lower than the adsorption pressure and higher than atmospheric pressure.
The amount of purge gas used in this step has to be appropriately controlled because it greatly changes the purity of the product gas recovered in the product gas recovery step that follows this step. In other words, if the amount of purge gas is too small, the poorly adsorbed components in the spaces between the adsorbents will not be sufficiently released to the outside of the adsorption tower, and the poorly adsorbed components will coexist in the product gas that is subsequently recovered. , no improvement in product gas purity can be expected. However, if too much product gas is refluxed as purge gas, although the purity of the product gas is improved, there is the disadvantage that the amount of product gas that can be used as a product is reduced. Therefore, it is desired to establish a method for optimally controlling the amount of purge gas depending on the situation and ensuring product gas purity and product gas amount. After conducting a detailed study on this point, the relationship shown in FIG. 3 was obtained. That is, the removal rate of poorly adsorbed components in the second stage treatment increases with the amount of purge gas used in the purge step. Therefore, when the concentration of poorly adsorbed components in the first stage product gas to be subjected to the second stage treatment is low, a purge operation with a low removal rate of the difficultly adsorbed components,
That is, it can be said from the relationship shown in FIG. 3 that even if the amount of purge gas is reduced, a constant product gas purity can be ensured. Therefore, it is necessary to actually measure the concentration of the difficult-to-adsorb component in the first-stage product gas, which is the raw material gas to be subjected to the second-stage treatment, or to predict it from the concentration in the raw material gas and the efficiency of carbon dioxide removal in the first-stage treatment. Based on the estimated concentration of the poorly adsorbed component in the first stage product gas, the removal rate of the poorly adsorbed component is determined by referring to the required product gas purity, and the amount of purge gas required for this is determined and a method for controlling it is determined. By adopting this method, it is possible to simultaneously ensure the purity of the product gas and the maximum amount of product gas recovered. In addition, in this purge step, the gas discharged from the adsorption tower is the product gas plus gas rich in poorly adsorbed components in the spaces between adsorbents, and the gas has a composition sufficiently rich in easily adsorbed components. product gas recovery,
Alternatively, it is preferable to introduce the gas into another adsorption tower that has completed the adsorption () step of recovering the reduced pressure gas to adsorb and recover easily adsorbable components, but it may also be disposed of outside the system. In step (), the adsorption tower after the purge step is heated to 300 Torr or less, preferably 300 Torr or less using a vacuum exhaust device.
The pressure is reduced to ~30 Torr, and the components adsorbed by the adsorbent are desorbed and recovered as product gas. In step (), the adsorption tower that has completed the product gas recovery and the adsorption tower that has completed the adsorption () process are connected, and the reduced pressure gas from the latter adsorption tower is introduced into the former adsorption tower, allowing it to be easily adsorbed by the adsorbent. Adsorption () process to adsorb components. Step () connects the adsorption tower that has completed the adsorption () process and the adsorption tower that has completed the depressurization and release process, and introduces the gas discharged from the purge process of the latter adsorption tower into the former adsorption tower, This is an adsorption () process in which easily adsorbable components are adsorbed onto an adsorbent. This step () is optional. Hereinafter, in a typical example of the present invention, carbon dioxide in the converter exhaust gas is first removed, and then nitrogen and nitrogen are removed.
The present invention will be explained in detail based on a method of removing hydrogen and separating and recovering carbon monoxide, but the method of the present invention is not limited to these specific examples. FIG. 4 is a flow sheet of a system for continuously separating and recovering carbon monoxide from converter exhaust gas by an adsorption cycle, and FIG. 5 is a flow sheet showing the concept of the control system of the system of FIG. In FIG. 5, GH represents the first and second stage processing devices, respectively. First, the adsorption operation will be explained based on FIG.
Adsorption towers A and B house adsorbents that selectively adsorb carbon dioxide. Adsorption tower A has completed the purge step, valves 1 to 6 are closed, and the adsorption tower pressure is reduced to 300 Torr or less, preferably 30 Torr. On the other hand, adsorption tower B has completed the adsorption process,
In order to start the pressure reduction process, all valves 4 to 12 are closed, and only valve 9 is open. Taking this state as a reference and focusing on the adsorption tower A, an example of the adsorption cycle is as follows. First, valve 6 is opened to introduce the first stage product gas into adsorption tower A. When the pressure in the adsorption tower A reaches an adsorption pressure of 0.01 to 3.0 Kg/cm 2 G, preferably 0.2 Kg to 1.0 Kg/cm 2 G, valve 6 is closed and valves 1 and 2 are opened to complete the adsorption process. The raw material gas is transferred to adsorption tower A while maintaining the pressure.
flow to. After completion of the adsorption process for a certain amount of raw material gas for a certain period of time, valves 1 and 2 are closed, and then valve 3 is opened to reduce the internal pressure of the adsorption tower to near atmospheric pressure. When the pressure in the adsorption tower A reaches near atmospheric pressure, the valve 3 is closed, then the valve 4 is opened, and the vacuum pump 40 is used to carry out depressurization and exhaust to desorb the carbon dioxide adsorbed on the adsorbent. The exhaust pressure at this time is 300 Torr or less, preferably
Exhaust until the temperature reaches 30Torr, then turn valve 5
A purge process is performed in which the waste gas from the second stage treatment equipment is introduced under reduced pressure. When the purge process is completed, valves 4 and 5 are closed. The next step is to return to the beginning and open valve 6. By sequentially repeating the above operations in each of the adsorption towers A and B, carbon dioxide is continuously adsorbed onto the adsorbent and removed. 1st
In the stage treatment, the first stage product gas from which carbon dioxide has been removed flowing out from the tops of adsorption towers A and B is introduced into the second stage treatment equipment, where hydrogen and nitrogen are removed and the gas is concentrated to a high concentration. It is recovered as carbon monoxide gas. Adsorption towers C, D, E, and F house adsorbents that selectively adsorb easily adsorbed components (carbon monoxide). Focusing on adsorption towers C and D,
The adsorption process will be explained. Adsorption tower C performs the adsorption () process,
This is based on the situation where adsorption tower D is in the product gas recovery process. At this time, the valves 18 and 17 are closed and the first stage product gas is flowing into the adsorption tower C.
The valve 27 is opened to allow the easily adsorbed components adsorbed on the adsorbent of the adsorption tower D to be desorbed and recovered as a product gas. The adsorption pressure of adsorption tower C is naturally determined by the pressure of the first stage product gas, but is 0.01 to 3.0 Kg/cm 2 G, preferably 0.2 to 1.0 Kg/cm 2
G is appropriate. On the other hand, in the product gas recovery process of adsorption tower D, the adsorption tower pressure is 300 Torr or less, preferably
It is desirable to maintain up to 30Torr. After the adsorption () process in which a certain amount of gas is passed through adsorption tower C for a certain period of time or a certain amount of gas is adsorbed onto the adsorbent, valves 18 and 17 are closed, and at the same time valve 27 is closed to recover the product gas from adsorption tower D. Finish the process. Next, valve 19 in the connecting pipe between adsorption towers C and D is opened to reduce the internal pressure of adsorption tower C to near atmospheric pressure. The gas released at this time is introduced into the adsorption tower D, and the easily adsorbable components are adsorbed onto the adsorbent (adsorption () step). When the internal pressure of the adsorption tower C approaches atmospheric pressure, the valve 20 is opened to introduce the product gas from the product gas tank 42 into the adsorption tower C, and a purge process is performed to expel the gas of the difficult-to-adsorb components present in the gaps between the adsorbents. . At this time, the gas flowing out from the top of the adsorption tower C is introduced into the adsorption tower D via the valve 19, and easily adsorbed components are adsorbed by the adsorbent (adsorption () step). When the purge process is finished, valve 1
9 and 20 are closed, valve 21 and valve 22
Let's open. With this operation, the adsorption tower C moves to the product gas recovery process under reduced pressure using the decompression exhaust equipment 41, while the adsorption tower D moves to the adsorption () process and the pressurization process using the first stage product gas following the adsorption () process. to go into. When the internal pressure of the adsorption tower D reaches the adsorption pressure due to the pressurization step, the valve 23 is opened and the adsorption tower D moves to the adsorption ( ) step. The above operations are the steps until the adsorption towers C and D return to the standard situation, although their roles have changed. By sequentially repeating this operation, carbon monoxide gas, which is an easily adsorbed component, can be continuously adsorbed onto the adsorbent for separation and purification. Incidentally, the adsorption towers E and F also repeat the same steps as those for C and D. Next, based on FIG. 5, the optimal operating method of this system will be described. The carbon dioxide and nitrogen concentrations in the raw material gas are continuously measured by an analyzer 45, those in the first stage product gas by an analyzer 46, and those in the product gas by an analyzer 47, respectively. Gas chromatography, infrared absorption meter, etc. can be used as the analyzer. These analysis signals are transmitted to computer 44 along with flowmeter (not shown) signals. Control for most efficient carbon dioxide removal in the first stage treatment is performed as follows. Based on the carbon dioxide concentration signal of the analyzer 45 and the raw material gas flow rate signal, the amount of carbon dioxide to be adsorbed is calculated by the computer 44, and the required purge gas volume is determined from the relationship shown in FIG.
Next, the amount of second-stage waste gas that can be used for purging is determined based on the flow rate signal, and the exhaust capacity of the decompression exhaust device 40 required to obtain the required purge gas volume is calculated. If the decompression exhaust device 40 is a variable voltage/frequency electric motor, for example, it is extremely easy to control the transmission of computer signals that match the required exhaust capacity, and it is also possible to install a plurality of decompression exhaust devices in series or in series. In this case, a system that supports driving and stopping of individual devices as necessary may be used. These operations make it possible to reliably remove carbon dioxide by increasing the exhaust capacity even when the carbon dioxide concentration in the raw material gas increases, and conversely, when the carbon dioxide concentration in the raw material gas decreases. By reducing the exhaust capacity, it is possible to reduce the operating power cost of the system. Next, a method for efficiently separating difficult-to-adsorb components, particularly nitrogen from carbon monoxide, in the second stage treatment will be explained. The nitrogen concentration in the first stage product gas is determined by the analyzer 46 (the concentration estimated by the computer 44 based on the nitrogen concentration in the raw material gas by the analyzer 45 may be used)
Then, calculate the removal rate of the difficult-to-adsorb components determined from the predetermined product gas purity, and from the relationship in Figure 2 or Figure 3,
The computer 44 performs an operation to determine the required amount of adsorption () process waste gas or the amount of product gas used in the purge process. Based on this, the opening degree of the flow rate control valve 14 that adjusts the amount of waste gas in the adsorption () process or the flow rate control valve 43 that adjusts the amount of purge gas is controlled.
This controls the opening of the valve. By performing one or both of the above operations at the same time, the flow control valve 1 can be
By increasing the opening degree of 4 and/or 43, the product gas purity can be kept constant by improving the nitrogen removal rate, and conversely, when the nitrogen concentration in the raw material gas is low, the amount of waste gas can be reduced. , the action of reducing the amount of purge gas can improve the product gas recovery rate and recovery amount of the system. In the above explanation, an example of feed forward control based on the raw material gas concentration signal was shown, but the analyzer 47
A system that performs feedback control based on the product gas concentration signal based on the relationships shown in FIGS. 1 to 3 is similarly effective. Note that activated carbon, activated alumina, synthetic or natural (including modified ones) zeolite, etc. are suitable as the adsorbent used in the adsorption tower for the first and second stage treatments. Examples Examples will be described to explain the effects of the present invention. Figure 6 shows the amount of N 2 and CO in the raw material gas and product gas when product gas is recovered using converter exhaust gas as the raw material using a system having the functions shown in the flow sheets of Figures 4 and 5. This is the result of continuous measurement of two concentrations. Example () does not use the dynamic control system shown in Fig. 5, but sets the capacity of the first stage decompression exhaust equipment appropriate for the initial raw material gas composition, and discards the adsorption process in the second stage treatment. This is the result of continuous operation with the gas amount and purge gas amount set in the purge process. Although product gas recovery with the required 99% CO purity has almost been achieved, depending on the raw material gas composition, the purity may deteriorate and reach around 98% CO in some cases. On the other hand, Example () is the result of performing control according to the control loop shown in FIG. 5 depending on the raw material gas composition, and a product gas containing 99% CO is stably recovered.
第１図はパージガス容積とCO2吸着量との関係
を示すグラフである；第２図及び第３図は吸着
（）工程廃棄ガス量と難吸着成分除去率との関係
を示すグラフである；第４図は本発明を実施する
好ましい装置のフローシートである；第５図は本
発明の操業システムのフローシートである；そし
て第６図は本発明を実施した際のN2、CO2連続
測定した結果を示すグラフである。
FIG. 1 is a graph showing the relationship between purge gas volume and CO 2 adsorption amount; FIGS. 2 and 3 are graphs showing the relationship between adsorption () process waste gas amount and hard-to-adsorb component removal rate; FIG. 4 is a flow sheet of a preferred apparatus for carrying out the present invention; FIG. 5 is a flow sheet for the operating system of the present invention; and FIG . It is a graph showing the measured results.
Claims (1)
素、二酸化炭素及び窒素を含有する原料ガス中の
一酸化炭素を濃縮分離する方法において (a) その第１段階の吸着操作は原料ガス中の二酸
化炭素に対して、選択吸着法を有する吸着物質
を収納した２つ以上の吸着塔を使用し、その方
法は各吸着塔で少なくとも吸着工程及びパージ
操作を含む脱着工程を繰り返す圧力変動式吸着
分離によつてその原料ガスから二酸化炭素を除
去することからなり、そして、 (b) 第２段階の吸着操作は、第１段階の吸着工程
から排出される二酸化炭素の除去されたガス
（以後第１段階製品ガスという）中の一酸化炭
素に対して選択性を有する吸着物質を充填した
２つ以上の吸着塔を使用し、その方法は、 () 第１段階製品ガスによる吸着塔の吸着工
程 () その吸着塔のパージ () 製品ガスの脱着回収 から成る少なくとも３工程を繰り返すことから
なり、第２段階処理の吸着工程から排出される
廃棄ガスを第１段階処理における吸着塔再生の
パージ工程に使用し、そして、 (c) 原料ガス中の少なくとも二酸化炭素と窒素ガ
ス濃度を計測して、或いは、製品ガス中の少な
くとも二酸化炭素と窒素ガス濃度を計測して、
その結果に基いて、次の三つの方法 () 第１段階処理のパージ工程で使用する減
圧排気機器の排気能力の制御 () 第２段階の処理の吸着工程の廃棄ガス量
の制御 () 第２段階処理のパージ工程に使用するパ
ージガス量の制御 のうち、少なくとも１つの操作を行なうことによ
り、一酸化炭素の濃縮分離を行なうことを特徴と
した方法。[Claims] 1. In a method for concentrating and separating carbon monoxide in a raw material gas containing at least carbon monoxide, carbon dioxide, and nitrogen by a two-stage adsorption operation, (a) the first stage adsorption operation For carbon dioxide in gas, two or more adsorption towers containing an adsorbent material that has a selective adsorption method are used, and each adsorption tower repeats at least an adsorption step and a desorption step including a purge operation. (b) The second stage adsorption operation consists of removing carbon dioxide from the feed gas by adsorption separation; (hereinafter referred to as the first stage product gas), the method comprises: The adsorption process consists of repeating at least three steps consisting of () purging of the adsorption tower, and () desorption and recovery of the product gas. (c) measuring at least the carbon dioxide and nitrogen gas concentrations in the raw material gas, or measuring at least the carbon dioxide and nitrogen gas concentrations in the product gas;
Based on the results, the following three methods () Control the exhaust capacity of the decompression exhaust equipment used in the purge process of the first stage treatment () Control the amount of waste gas in the adsorption process of the second stage treatment () A method characterized in that carbon monoxide is concentrated and separated by performing at least one operation of controlling the amount of purge gas used in a purge step of a two-stage treatment.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59012586A JPS60155521A (en) | 1984-01-26 | 1984-01-26 | Process for purifying carbon monoxide from mixed gas containing carbon monoxide using adsorption process |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59012586A JPS60155521A (en) | 1984-01-26 | 1984-01-26 | Process for purifying carbon monoxide from mixed gas containing carbon monoxide using adsorption process |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS60155521A JPS60155521A (en) | 1985-08-15 |
| JPS6410443B2 true JPS6410443B2 (en) | 1989-02-21 |
Family
ID=11809455
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP59012586A Granted JPS60155521A (en) | 1984-01-26 | 1984-01-26 | Process for purifying carbon monoxide from mixed gas containing carbon monoxide using adsorption process |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS60155521A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2021140151A1 (en) | 2020-01-08 | 2021-07-15 | Arnold Jäger Holding GmbH | Strip aerator and aerator assembly |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP5061482B2 (en) * | 2006-03-27 | 2012-10-31 | Ｊｆｅスチール株式会社 | Method for separating and recovering carbon monoxide in source gas |
| WO2020067181A1 (en) * | 2018-09-25 | 2020-04-02 | 積水化学工業株式会社 | Gas treatment method and gas treatment device |
| JP7787227B2 (en) * | 2024-05-08 | 2025-12-16 | 大陽日酸株式会社 | Gas separation method and gas separation device |
-
1984
- 1984-01-26 JP JP59012586A patent/JPS60155521A/en active Granted
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2021140151A1 (en) | 2020-01-08 | 2021-07-15 | Arnold Jäger Holding GmbH | Strip aerator and aerator assembly |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS60155521A (en) | 1985-08-15 |
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