JP5098121B2 - Method for desulfurization of hydrogen sulfide-containing gas - Google Patents
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Description
【０００１】
【発明の属する技術分野】
本発明は硫化水素含有ガスの脱硫方法に係り、特に、下水、し尿、産業排水、汚泥、ゴミ等の有機性物質の嫌気性微生物消化により発生する硫化水素を含有する消化ガスから、硫化水素を効率的に除去するための方法に関する。
【０００２】
【従来の技術】
従来、下水、し尿、産業排水等の排水、又は汚泥、ゴミ等の固形廃棄物などの有機性物質の処理法として、嫌気性微生物消化（嫌気性消化）法がある。嫌気性消化法においてメタン発酵により発生するメタンを含む消化ガス（バイオガス）は、通常、エネルギー回収の目的で、ボイラや焼却炉の燃料などとして有効利用されている。
【０００３】
しかし、消化ガス中には、メタンの他、二酸化炭素、硫化水素等が含まれていることから、ボイラや焼却炉の燃料等として有効利用するに当っては、設備機器の腐食や大気汚染を防止する目的で含有される硫化水素を除去（脱硫）する必要がある。
【０００４】
従来、消化ガスの脱硫方法として、水酸化ナトリウム等のアルカリに硫化水素を吸収させるアルカリ吸収法が提案されているが、アルカリ吸収法は薬品使用量が多く、ランニングコストが高いという欠点がある。
【０００５】
これに対して、硫化水素を微生物により酸化分解して除去する生物脱硫法であれば、比較的低コストにて処理を行うことができる。従来、生物脱硫法による消化ガスの脱硫装置として、硫化物を微生物によって酸化分解する生物脱硫塔と、該生物脱硫塔内に散水する散水手段と、被処理ガスを該生物脱硫塔に導入する手段と、処理ガスを該生物脱硫塔から排出する手段と、該生物脱硫塔から排水する排水手段と、前記排水手段から排出された生物脱硫塔排水を曝気処理する曝気槽と、該曝気槽の曝気処理液を膜濾過する膜濾過装置と、該膜濾過装置の濃縮水を前記散水手段に送給する手段とを備えてなるものが提案されている（特開平９−２６２４２９号公報）。
【０００６】
この硫化物含有ガスの脱硫装置において、生物脱硫塔における硫化物の生物脱硫、例えば、硫化水素を酸化分解する微生物が担持された充填材層を有する生物脱硫塔における硫化水素の生物脱硫は、次のようにして行われる。
【０００７】
即ち、生物脱硫塔内に導入された被処理ガス中の硫化水素が充填材の表面の水に吸収される。そして、微生物が塔内に散水された水中の溶存酸素を利用してこの硫化水素の大部分を硫酸にまで完全に酸化分解する。硫化水素の酸化分解で生成した硫酸及び未分解の硫化水素は生物脱硫塔排水中に含有されて排出されるが、この生物脱硫塔排水中には、硫酸及び硫化水素と共に、充填材層で増殖し、散水により流出した微生物が含有されている。
【０００８】
この生物脱硫塔排水は曝気槽で曝気されることにより空気（酸素）が吹き込まれ、排水中の未分解の硫化水素がこの曝気槽内で酸化分解され、また、水中の酸素が飽和する。そして、この溶存酸素を十分に含む曝気処理液は、膜濾過装置で膜濾過され、硫酸、その他の溶解成分を含む膜濾過水が系外へ排出される。一方、生物脱硫塔から流出した微生物が濃縮され、また、曝気による溶存酸素を多量に含む濃縮水は返送されて生物脱硫塔に散水される。
【０００９】
このように、膜濾過で生物脱硫塔から流出した微生物が濃縮されると共に、曝気により多量の溶存酸素が吹き込まれた水を散水するため、酸素を含まない消化ガスであっても完全に酸化分解して、効率的に生物脱硫処理することができる。
【００１０】
なお、この脱硫装置では、生物脱硫塔の散水中の溶存酸素を生物脱硫の酸素源としており、十分な脱硫を行うために散水量を比較的多くする必要がある。このためには例えば、充填材層を設けた生物脱硫塔において、充填材として比較的大きさの大きいものを用いる必要がある。このように粗大な充填材を用い、多量の散水を行うと、微生物は特に充填材から剥離し易くなり、生物脱硫塔からの微生物の流出量が多くなるが、この流出した微生物は膜濾過装置で濃縮されて循環されるため、微生物の流失を防止して効率的な生物脱硫を行うことができる。
【００１１】
【発明が解決しようとする課題】
しかしながら、上記生物脱硫法では、消化ガス等の硫化水素含有ガス中の硫化水素を除去して硫化水素濃度５００ｐｐｍ以下の処理ガスを得るためには、大容量の設備が必要となり、工業的に不利である。
【００１２】
一方、アルカリ吸収法では、前述の如く、アルカリ使用量が多いことから、特に、この方法で高濃度の硫化水素含有ガスを処理すると、大量のアルカリが必要となり、経済的に不利である。
【００１３】
本発明は上記従来の問題点を解決し、硫化水素含有ガスを大容量の設備を必要とすることなく、また多量のアルカリを使用することなく、低コストで効率的に処理して、硫化水素濃度の低い処理ガスを得ることができる硫化水素含有ガスの脱硫方法を提供することを目的とする。
【００１４】
【課題を解決するための手段】
本発明の硫化水素含有ガスの脱硫方法は、硫化水素を含む原ガスを活性汚泥処理水と接触させて、原ガス中の硫化水素を粗取りする一次脱硫工程と、該一次脱硫工程の処理ガスを湿式又は乾式でアルカリと接触させてガス中に残留する硫化水素を除去する二次脱硫工程とを有し、前記一次脱硫工程において、前記原ガス中の硫化水素の８０〜９５％を除去し、硫化水素濃度１００〜５００ｐｐｍの一次脱硫処理ガスを得、これを前記二次脱硫工程に送給して二次脱硫処理する硫化水素含有ガスの脱硫方法であって、前記一次脱硫工程において、硫化水素を酸化分解する微生物が担持された充填材層が内部に設けられており、また、この充填材層に活性汚泥処理水を散水する散水ノズルが充填材層の上方に取り付けられている生物脱硫塔の下部に前記原ガスを導入し、該生物脱硫塔の上部からの一次脱硫処理ガスを前記二次脱硫工程に送給し、前記生物脱硫塔の原ガスの通ガス速度がＳＶ１０〜２０ｈｒ −１ で、散水量が液ガス比として０．４〜０．８であり、前記二次脱硫工程において、内部に充填材層が設けられており、また、この充填材層に散水するアルカリ吸収液の散水ノズルが設けられているアルカリ吸収塔に前記一次脱硫処理ガスを導入してアルカリ吸収液と向流接触させ、前記アルカリ吸収液が、ｐＨ８〜１３の苛性ソーダ水溶液又は苛性カリ水溶液であり、前記アルカリ吸収塔の通ガス速度がＳＶ５０〜２００ｈｒ −１ で、液ガス比が０．０１〜０．２であり、前記二次脱硫工程から排出される処理ガスの硫化水素濃度が５０ｐｐｍ以下であることを特徴とする。
【００１５】
本発明においては、一次脱硫工程で生物脱硫法により原ガス中の硫化水素を粗取りした後、二次脱硫工程でアルカリ吸収法により残留する硫化水素を除去するため、一次脱硫工程においては、硫化水素を高度に除去するための大容量な設備を必要とすることなく、また、二次脱硫工程では、残留する少量の硫化水素を除去するのみで良いことから、少量のアルカリ使用量で高度な脱硫を行って、低硫化水素濃度の処理ガスを得ることができる。
【００１６】
【発明の実施の形態】
以下に図面を参照して実施の形態を詳細に説明する。
【００１７】
図１は本発明の硫化水素含有ガスの脱硫方法の実施の形態を示す系統図である。
【００１８】
図１において、１は生物脱硫塔であり、硫化水素を酸化分解する微生物が担持された充填材層２が内部に設けられており、また、この充填材層２に散水する散水ノズル３が充填材層２の上方に取り付けられている。
【００１９】
４はアルカリ吸収塔であり、内部に気液接触効率の向上のための充填材層５が設けられており、また、この充填材層５に散水する散水ノズル６が設けられている。
【００２０】
消化ガス等の硫化水素を含有する原ガスは、配管１１より、まず、この生物脱硫塔１の下部に導入され、原ガス中の硫化水素は充填材の表面の水に吸収され、充填材に担持された微生物が、配管１２より塔内に導入され、散水ノズル３より散水された生物吸収液中の溶存酸素を利用してこの硫化水素の大部分を硫酸にまで完全に酸化分解し、処理ガスは生物脱硫塔１の上部の配管１４より後段のアルカリ吸収塔４に送給される。硫化水素の酸化分解で生成した硫酸及び未分解の硫化水素を吸収した吸収排液は配管１３より排出され、曝気槽（図示せず）に導入されて生物処理される。
【００２１】
生物脱硫塔１の充填材としては、特に制限はないが、多孔性焼結物、プラスチック、コークス、スポンジなど、微生物が担持されやすく、表面積が大きく、通気性、排水性が良いものが適当である。なお、本発明においては、前述の如く、散水量を比較的多くするために、この充填材は比較的大きさの大きいものであることが好ましく、一般的には直径５〜６０ｍｍ，高さ１０〜６０ｍｍの円柱又は円筒形、或いは２０〜５０ｍｍ×２０〜５０ｍｍ×２０〜５０ｍｍの塊状であることが好ましい。また、その充填量は生物脱硫塔１の有効容積の５０〜８０％程度とするのが好ましい。
【００２２】
生物脱硫塔１に供給する生物吸収液としては、生物処理水を使用する。特に活性汚泥処理水であれば、そのアルカリ度（通常ｐＨ６〜８程度）にてアルカリを補給し、かつＳＳ濃度が数ｍｇ／Ｌ〜３０ｍｇ／Ｌと低いので充填材２の目詰まりを防ぎ、吸収液のｐＨ低下に対する緩衝作用もある上に、硫黄酸化細菌への最小限の栄養源（窒素、リン、ミネラル等）の供給を補完できることから好ましい。
【００２３】
散水により生物脱硫に必要とされる酸素を十分に供給するための散水量、即ち、散水ノズル３に送給される水量は、装置の規模や原ガスの硫化水素濃度及び処理量等によっても異なるが、一般的には、原ガスの通ガス速度がＳＶ１０〜２０ｈｒ−１ で、液ガス比０．４〜０．８とする。
【００２４】
本発明では、このような生物脱硫処理により、原ガス中の硫化水素の８０〜９５％を除去し、硫化水素濃度１００〜５００ｐｐｍ程度の一次脱硫処理ガスを得、これを後段のアルカリ吸収塔４に送給して二次脱硫処理を行うのが好ましい。
【００２５】
アルカリ吸収塔４では、配管１４より塔下部に導入された生物脱硫塔１からの一次脱硫処理ガスが、配管１５から導入され、散水ノズル６より散水されるアルカリ吸収液と塔内で向流接触し、ガス中になお残留する硫化水素がアルカリ吸収液に吸収除去され、処理ガスは塔上部の配管１７より系外へ排出され、ボイラ、燃焼炉等の使用場所へ送給される。
【００２６】
一方、硫化水素を吸収した吸収排液は塔下部の配管１６より系外へ排出される。この吸収排液は、一次脱硫工程のｐＨ調整剤として利用可能である。
【００２７】
この処理ガスは予め原ガス中の硫化水素の大部分を生物脱硫塔１で除去した後、アルカリ吸収により硫化水素を高度に除去して得られるものであり、硫化水素濃度が５０ｐｐｍ以下と著しく低い。しかも、このように硫化水素を高度に除去するためのアルカリ使用量も少量で足りる。
【００２８】
このアルカリ吸収塔４の充填材としては、生物脱硫塔１の充填材と同様なものを用いることができる。
【００２９】
このアルカリ吸収塔４のアルカリ吸収液としては、ｐＨが高い程硫化水素の吸収効率に優れるが、取り扱い性等を考慮した場合、ｐＨ８〜１３の苛性ソーダ水溶液又は苛性カリ水溶液を用いる。
【００３０】
このアルカリ吸収塔４の通ガス速度はＳＶ５０〜２００ｈｒ−１、液ガス比は０．０１〜０．２とするのが硫化水素の吸収効率の面で好ましい。
【００３１】
本発明において、アルカリ吸収塔４で吸収除去する硫化水素量は、生物脱硫塔１で除去する硫化水素量に比べて著しく少なく吸収効率が大きいことから、通常の場合、このアルカリ吸収塔４の容積は、生物脱硫塔１の容積の１／１０〜１／２０程度とすることができる。
【００３２】
本発明で処理対象とする硫化水素を含有する原ガスは、例えば、下水、し尿、産業排水等の排水及び汚泥、ゴミ等の固形廃棄物などの有機性物質を嫌気性消化する際、メタン発酵により発生する消化ガス、その他、ゴミ処分地、堆肥化施設等から発生する悪臭ガス等が挙げられる。
【００３３】
【実施例】
以下に実施例及び比較例を挙げて本発明をより具体的に説明する。
【００３４】
実施例１
硫化水素濃度２０００ｐｐｍ、二酸化炭素濃度２０体積％で、メタンガスが残部約８０体積％の消化ガスを図１に示す２段脱硫法にて処理した。
【００３５】
生物脱硫塔１の生物吸収液としてはｐＨ７．５の活性汚泥処理水を使用した。この生物脱硫塔１は容積４００Ｌの塔内に充填材としてポリプロピレン製のネットリング（大日本プラスチック（株）登録商標）（寸法内径４５ｍｍ×外径５２ｍｍ×長さ５２ｍｍの円筒形）を２５０Ｌ充填したものであり、通ガス速度ＳＶ２０ｈｒ−１、液ガス比０．６で脱硫処理を行った。
【００３６】
アルカリ吸収塔４のアルカリ吸収液としては工水に苛性ソーダを添加してｐＨ１２に調整したものを用いた。このアルカリ吸収塔４は、容積５０Ｌの塔内に充填材として上記ネットリングを４０Ｌ充填したものであり、通ガス速度ＳＶ２０ｈｒ−１、液ガス比０．０１で脱硫処理を行った。
【００３７】
このときの生物脱硫塔１の入口ガス及び出口ガスの硫化水素濃度及びアルカリ吸収塔４の出口ガスの硫化水素濃度は表１に示す通りであり、硫化水素が低濃度にまで除去された処理ガスを得ることができた。
【００３８】
【表１】
比較例１
実施例１において、アルカリ吸収塔を用いず、生物脱硫塔のみで同組成の消化ガスの生物脱硫処理を行い、得られた処理ガスの硫化水素濃度を表２に示した。なお、用いる生物脱硫塔の容積は表２に示す通り種々変えて処理を行った。
【００４０】
【表２】
表２より明らかなように、生物脱硫とアルカリ吸収の二段処理を行った実施例１で得られた処理ガス濃度と同じ硫化水素濃度を得るためには、実施例１の二段脱硫処理３５０Ｌ（生物脱硫塔３００Ｌ＋アルカリ吸収塔５０Ｌ）の容積規模に対し、生物脱硫のみでは二段脱硫処理の約２倍である７００Ｌの容積規模で吸収操作を行う必要があった。
【００４２】
比較例２
実施例１において、生物脱硫塔を用いず、アルカリ吸収塔のみで同組成の消化ガスのアルカリ脱硫を行い、得られた処理ガスの硫化水素濃度を表３に示した。なお、用いるアルカリ吸収塔の容積は表３に示す通り種々変えて処理を行った。
【００４３】
【表３】
表３より明らかなように、アルカリ吸収塔容積１００Ｌの場合において、実施例１の場合と同程度の処理ガスが得られた。この容積１００Ｌのアルカリ吸収塔を使用して５０ｍ３のガスを処理するために必要な苛性ソーダの使用量を測定し、１ｋｇのイオウを処理するのに必要な２５％苛性ソーダの量を実施例１の場合と比較したところ、表４に示す通りであり、アルカリ吸収のみで同じ量のガスを処理する場合の苛性ソーダ使用量は、実施例１の二段脱硫処理を実施した場合と比較して３．６倍もの量になることが確認された。
【００４５】
【表４】
以上の実施例１及び比較例１，２の結果から、同じガス量を処理するにあたって、生物脱硫とアルカリ吸収の二段脱硫処理を実施した場合、生物脱硫のみで処理した場合と比較して設備規模を２分の１にすることができ、また、アルカリ吸収のみで処理した場合に比較して必要な苛性ソーダ使用量は約３．６分の１程度に削減できることが確認された。
【００４７】
【発明の効果】
以上詳述した通り、本発明の硫化水素含有ガスの脱硫方法によれば、硫化水素含有ガスを大容量の設備を必要とすることなく、また多量のアルカリを使用することなく、低コストで効率的に処理して、硫化水素濃度の低い処理ガスを得ることができる。
【図面の簡単な説明】
【図１】 本発明の硫化水素含有ガスの脱硫方法の実施の形態を示す系統図である。
【符号の説明】
１ 生物脱硫塔
２，５ 充填材層
３，６ 散水ノズル
４ アルカリ吸収塔[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for desulfurizing a hydrogen sulfide-containing gas, and in particular, hydrogen sulfide from a digestion gas containing hydrogen sulfide generated by anaerobic microbial digestion of organic substances such as sewage, human waste, industrial wastewater, sludge, and garbage. It relates to a method for efficient removal.
[0002]
[Prior art]
Conventionally, there is an anaerobic microbial digestion (anaerobic digestion) method as a method for treating organic substances such as sewage, human waste, wastewater such as industrial wastewater, or solid waste such as sludge and garbage. Digestion gas (biogas) containing methane generated by methane fermentation in an anaerobic digestion method is usually effectively used as fuel for boilers and incinerators for the purpose of energy recovery.
[0003]
However, digestion gas contains carbon dioxide, hydrogen sulfide, etc. in addition to methane. Therefore, when used effectively as fuel for boilers and incinerators, etc., corrosion and air pollution of equipment and equipment will be avoided. It is necessary to remove (desulfurize) hydrogen sulfide contained for the purpose of prevention.
[0004]
Conventionally, as a digestion gas desulfurization method, an alkali absorption method in which hydrogen sulfide is absorbed by an alkali such as sodium hydroxide has been proposed. However, the alkali absorption method has a disadvantage that a large amount of chemicals is used and a running cost is high.
[0005]
In contrast, a biological desulfurization method in which hydrogen sulfide is removed by oxidative decomposition using microorganisms can be processed at a relatively low cost. Conventionally, as a desulfurization apparatus for digestion gas by a biological desulfurization method, a biological desulfurization tower that oxidatively decomposes sulfides with microorganisms, a watering means for sprinkling water into the biological desulfurization tower, and a means for introducing a gas to be treated into the biological desulfurization tower A means for discharging the treatment gas from the biological desulfurization tower, a drain means for draining from the biological desulfurization tower, an aeration tank for aeration treatment of the biological desulfurization tower drain discharged from the drain means, and an aeration of the aeration tank A device comprising a membrane filtration device for membrane-treating the treatment liquid and a means for feeding the concentrated water of the membrane filtration device to the watering means has been proposed (Japanese Patent Laid-Open No. 9-262429).
[0006]
In this sulfide-containing gas desulfurization apparatus, the biological desulfurization of sulfide in the biological desulfurization tower, for example, the biological desulfurization of hydrogen sulfide in the biological desulfurization tower having a filler layer loaded with microorganisms that oxidatively decompose hydrogen sulfide is as follows. It is done like this.
[0007]
That is, hydrogen sulfide in the gas to be treated introduced into the biological desulfurization tower is absorbed by the water on the surface of the filler. Microorganisms completely oxidize and decompose most of the hydrogen sulfide into sulfuric acid using dissolved oxygen in the water sprinkled in the tower. Sulfuric acid produced by oxidative decomposition of hydrogen sulfide and undecomposed hydrogen sulfide are contained and discharged in the biological desulfurization tower effluent. In this biological desulfurization tower effluent, sulfuric acid and hydrogen sulfide are propagated in the filler layer. However, it contains microorganisms that have flowed out due to watering.
[0008]
Air (oxygen) is blown into the biological desulfurization tower waste water by being aerated in an aeration tank, undecomposed hydrogen sulfide in the waste water is oxidized and decomposed in the aeration tank, and oxygen in water is saturated. Then, the aeration treatment liquid sufficiently containing dissolved oxygen is subjected to membrane filtration by a membrane filtration device, and membrane filtrate containing sulfuric acid and other dissolved components is discharged out of the system. On the other hand, the microorganisms flowing out from the biological desulfurization tower are concentrated, and the concentrated water containing a large amount of dissolved oxygen by aeration is returned and sprinkled on the biological desulfurization tower.
[0009]
In this way, the microorganisms flowing out from the biological desulfurization tower are concentrated by membrane filtration, and the water in which a large amount of dissolved oxygen is blown by aeration is sprinkled, so even digestion gas that does not contain oxygen is completely oxidatively decomposed Thus, the biological desulfurization treatment can be efficiently performed.
[0010]
In this desulfurization apparatus, dissolved oxygen in the sprinkling water of the biological desulfurization tower is used as an oxygen source for biological desulfurization, and the amount of sprinkling needs to be relatively large in order to perform sufficient desulfurization. For this purpose, for example, in a biological desulfurization tower provided with a filler layer, it is necessary to use a relatively large filler. When such a coarse filler is used and a large amount of water is sprayed, microorganisms are particularly easily detached from the filler, and the amount of microorganisms flowing out from the biological desulfurization tower increases. Since the water is concentrated and circulated, it is possible to prevent the loss of microorganisms and perform efficient biological desulfurization.
[0011]
[Problems to be solved by the invention]
However, in the above biological desulfurization method, in order to remove hydrogen sulfide in a hydrogen sulfide-containing gas such as digestion gas to obtain a treatment gas having a hydrogen sulfide concentration of 500 ppm or less, a large capacity facility is required, which is industrially disadvantageous. It is.
[0012]
On the other hand, in the alkali absorption method, as described above, since the amount of alkali used is large, particularly when a high concentration hydrogen sulfide-containing gas is treated by this method, a large amount of alkali is required, which is economically disadvantageous.
[0013]
The present invention solves the above-mentioned conventional problems and efficiently treats hydrogen sulfide-containing gas at low cost without requiring a large capacity facility and without using a large amount of alkali. It is an object of the present invention to provide a method for desulfurizing a hydrogen sulfide-containing gas that can obtain a treatment gas having a low concentration.
[0014]
[Means for Solving the Problems]
The desulfurization method for a hydrogen sulfide-containing gas according to the present invention includes a primary desulfurization step in which a raw gas containing hydrogen sulfide is brought into contact with activated sludge treated water to roughly remove hydrogen sulfide in the raw gas, and a treatment gas in the primary desulfurization step And a secondary desulfurization step for removing hydrogen sulfide remaining in the gas by contacting with alkali in a wet or dry manner, and in the primary desulfurization step, 80 to 95% of the hydrogen sulfide in the raw gas is removed. A hydrogen sulfide-containing gas desulfurization method comprising obtaining a primary desulfurization treatment gas having a hydrogen sulfide concentration of 100 to 500 ppm and supplying the gas to the secondary desulfurization step to perform a secondary desulfurization treatment. Biodesulfurization in which a filler layer carrying microorganisms that oxidatively decompose hydrogen is provided, and a water spray nozzle for spraying activated sludge treated water is attached to the filler layer above the filler layer Bottom of tower Introducing the raw gas, a primary desulfurization process gas from the top of the organism desulfurizer is fed to the secondary desulfurization step, passing the gas velocity of the raw gas in the biological desulfurization tower in SV10～20hr -1, dispersion The amount of water is 0.4 to 0.8 as a liquid gas ratio, and in the secondary desulfurization step, a filler layer is provided inside, and a water spray nozzle for alkaline absorbing liquid that sprinkles the filler layer is provided. The primary desulfurization treatment gas is introduced into an alkali absorption tower provided and brought into countercurrent contact with the alkali absorption liquid. The alkali absorption liquid is a caustic soda aqueous solution or a caustic potassium aqueous solution having a pH of 8 to 13, and the alkali absorption liquid is passed through the alkali absorption liquid. in gas velocity SV50～200hr -1, liquid-to-gas ratio is 0.01 to 0.2, hydrogen sulfide concentration in the treated gas discharged from the secondary desulfurization process is characterized in der Rukoto below 50ppm .
[0015]
In the present invention, hydrogen sulfide in the raw gas is roughly removed by the biological desulfurization process in the primary desulfurization process, and then the remaining hydrogen sulfide is removed by the alkali absorption process in the secondary desulfurization process. The secondary desulfurization process only requires removal of a small amount of residual hydrogen sulfide without the need for a large-capacity facility for removing hydrogen to a high degree. By performing desulfurization, a treatment gas having a low hydrogen sulfide concentration can be obtained.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments will be described in detail with reference to the drawings.
[0017]
FIG. 1 is a system diagram showing an embodiment of the method for desulfurizing a hydrogen sulfide-containing gas according to the present invention.
[0018]
In FIG. 1, reference numeral 1 denotes a biological desulfurization tower, in which a filler layer 2 carrying microorganisms that oxidatively decompose hydrogen sulfide is provided, and a filler nozzle 3 for spraying water is filled in the filler layer 2. It is attached above the material layer 2.
[0019]
Reference numeral 4 denotes an alkali absorption tower, in which a filler layer 5 for improving the gas-liquid contact efficiency is provided, and a watering nozzle 6 for sprinkling water to the filler layer 5 is provided.
[0020]
The raw gas containing hydrogen sulfide such as digestion gas is first introduced into the lower part of the biological desulfurization tower 1 from the pipe 11, and the hydrogen sulfide in the raw gas is absorbed by the water on the surface of the filler and becomes the filler. The supported microorganisms are introduced into the tower through the
[0021]
The filler for the biological desulfurization tower 1 is not particularly limited, but a porous sintered material, plastic, coke, sponge, etc., which are easy to carry microorganisms, have a large surface area, and have good air permeability and drainage are suitable. is there. In the present invention, as described above, in order to relatively increase the amount of water sprayed, it is preferable that the filler is relatively large, and generally has a diameter of 5 to 60 mm and a height of 10 It is preferable that it is a cylindrical or cylindrical shape of ˜60 mm, or a lump shape of 20-50 mm × 20-50 mm × 20-50 mm. The filling amount is preferably about 50 to 80% of the effective volume of the biological desulfurization tower 1.
[0022]
Biologically treated water is used as the biological absorbent supplied to the biological desulfurization tower 1. Especially if it is activated sludge treated water, alkali is replenished with its alkalinity (usually about pH 6 to 8), and the SS concentration is as low as several mg / L to 30 mg / L, so clogging of the filler 2 is prevented, In addition to having a buffering effect on the pH reduction of the absorbing solution, it is preferable because supply of a minimum amount of nutrients (nitrogen, phosphorus, minerals, etc.) to the sulfur-oxidizing bacteria can be complemented.
[0023]
The amount of water sprayed to sufficiently supply oxygen necessary for biological desulfurization by watering, that is, the amount of water fed to the watering nozzle 3 varies depending on the scale of the apparatus, the concentration of hydrogen sulfide in the raw gas, the amount of treatment, and the like. However, in general, the feed rate of the raw gas is SV10 to 20 hr −1 , and the liquid gas ratio is 0.4 to 0.00. 8 and you.
[0024]
In the present invention, 80 to 95% of the hydrogen sulfide in the raw gas is removed by such a biological desulfurization treatment to obtain a primary desulfurization treatment gas having a hydrogen sulfide concentration of about 100 to 500 ppm. The secondary desulfurization treatment is preferably performed by feeding to
[0025]
In the alkali absorption tower 4, the primary desulfurization treatment gas from the biological desulfurization tower 1 introduced from the
[0026]
On the other hand, the absorbed effluent that has absorbed hydrogen sulfide is discharged out of the system through the
[0027]
This treatment gas is obtained by removing most of the hydrogen sulfide in the raw gas in advance with the biological desulfurization tower 1 and then highly removing hydrogen sulfide by alkali absorption, and the hydrogen sulfide concentration is as low as 50 ppm or less. . In addition, the amount of alkali used for removing hydrogen sulfide to a high degree is sufficient.
[0028]
As the filler for the alkali absorption tower 4, the same filler as that for the biological desulfurization tower 1 can be used .
[0029]
As the alkali absorbing solution of the alkali absorption column 4, is excellent in absorption efficiency of the hydrogen sulphide as the pH is higher, in consideration of handling properties, etc., Ru with caustic soda solution or caustic potash solution of pH8~1 3.
[0030]
The alkali absorption tower 4 has a gas passing speed of SV50 to 200 hr −1 and a liquid gas ratio of 0.01 to 0.00. 2 is preferable in terms of absorption efficiency of hydrogen sulfide.
[0031]
In the present invention, the amount of hydrogen sulfide absorbed and removed by the alkali absorption tower 4 is significantly smaller than the amount of hydrogen sulfide removed by the biological desulfurization tower 1 and the absorption efficiency is large. Can be about 1/10 to 1/20 of the volume of the biological desulfurization tower 1 .
[0032]
The raw gas containing hydrogen sulfide to be treated in the present invention is, for example, methane fermentation when anaerobic digestion of sewage, human waste, industrial wastewater and other organic substances such as sludge and solid waste such as garbage. Digestive gas generated by the above, other malodorous gases generated from garbage disposal sites, composting facilities, and the like.
[0033]
【Example】
Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.
[0034]
Example 1
Digestion gas having a hydrogen sulfide concentration of 2000 ppm and a carbon dioxide concentration of 20% by volume and a balance of about 80% by volume of methane gas was treated by the two-stage desulfurization method shown in FIG.
[0035]
As the biological absorbent of the biological desulfurization tower 1, activated sludge treated water having a pH of 7.5 was used. This biological desulfurization tower 1 is packed with 250 L of polypropylene net ring (Dainippon Plastic Co., Ltd. registered trademark) (a cylinder with dimensions of inner diameter 45 mm × outer diameter 52 mm × length 52 mm) as a filler in a 400 L capacity column. The desulfurization treatment was performed at a gas flow rate of SV20 hr −1 and a liquid gas ratio of 0.6.
[0036]
As the alkali absorbing liquid of the alkali absorbing tower 4, a solution adjusted to
[0037]
The hydrogen sulfide concentrations of the inlet gas and outlet gas of the biological desulfurization tower 1 and the hydrogen sulfide concentration of the outlet gas of the alkali absorption tower 4 at this time are as shown in Table 1, and the processing gas from which hydrogen sulfide has been removed to a low concentration Could get.
[0038]
[Table 1]
Comparative Example 1
In Example 1, the digestion gas having the same composition was subjected to the biological desulfurization treatment using only the biological desulfurization tower without using the alkali absorption tower, and the hydrogen sulfide concentration of the obtained treatment gas is shown in Table 2. In addition, the volume of the biological desulfurization tower to be used was changed as shown in Table 2 for the treatment.
[0040]
[Table 2]
As is clear from Table 2, in order to obtain the same hydrogen sulfide concentration as the treatment gas concentration obtained in Example 1 in which the two-stage treatment of biological desulfurization and alkali absorption was performed, the two-stage desulfurization treatment 350L of Example 1 was performed. In comparison with the volume scale of (biodesulfurization tower 300L + alkali absorption tower 50L), it was necessary to carry out the absorption operation on a volume scale of 700L, which is about twice that of the two-stage desulfurization process with biodesulfurization alone.
[0042]
Comparative Example 2
In Example 1, alkali desulfurization of digestion gas having the same composition was carried out using only an alkali absorption tower without using a biological desulfurization tower, and the hydrogen sulfide concentration of the obtained treatment gas is shown in Table 3. In addition, the volume of the alkali absorption tower to be used was variously changed as shown in Table 3.
[0043]
[Table 3]
As is clear from Table 3, in the case of an alkali absorption tower volume of 100 L, a processing gas of the same level as in Example 1 was obtained. Using this 100 L alkaline absorption tower, the amount of caustic soda required to treat 50 m 3 gas was measured, and the amount of 25% caustic soda required to treat 1 kg of sulfur was determined as in Example 1. As compared with the case, it is as shown in Table 4. The amount of caustic soda used in the case of treating the same amount of gas with only alkali absorption is 3. Compared with the case of carrying out the two-stage desulfurization treatment of Example 1. It was confirmed that the amount was 6 times.
[0045]
[Table 4]
From the results of Example 1 and Comparative Examples 1 and 2 above, when treating the same amount of gas, when performing two-stage desulfurization treatment of biodesulfurization and alkali absorption, compared with the case of treatment only with biodesulfurization It was confirmed that the scale could be halved and that the required amount of caustic soda used could be reduced to about one-third compared to the case of treatment with only alkali absorption.
[0047]
【Effect of the invention】
As described above in detail, according to the method for desulfurizing a hydrogen sulfide-containing gas of the present invention, the hydrogen sulfide-containing gas is efficient at a low cost without requiring a large capacity facility and without using a large amount of alkali. Can be processed to obtain a processing gas having a low hydrogen sulfide concentration.
[Brief description of the drawings]
FIG. 1 is a system diagram showing an embodiment of a method for desulfurizing a hydrogen sulfide-containing gas according to the present invention.
[Explanation of symbols]
1 Biological desulfurization tower 2,5 Packing material layer 3,6 Sprinkling nozzle 4 Alkali absorption tower
Claims (2)
該一次脱硫工程の処理ガスを湿式又は乾式でアルカリと接触させてガス中に残留する硫化水素を除去する二次脱硫工程とを有し、
前記一次脱硫工程において、前記原ガス中の硫化水素の８０〜９５％を除去し、硫化水素濃度１００〜５００ｐｐｍの一次脱硫処理ガスを得、これを前記二次脱硫工程に送給して二次脱硫処理する硫化水素含有ガスの脱硫方法であって、
前記一次脱硫工程において、硫化水素を酸化分解する微生物が担持された充填材層が内部に設けられており、また、この充填材層に活性汚泥処理水を散水する散水ノズルが充填材層の上方に取り付けられている生物脱硫塔の下部に前記原ガスを導入し、該生物脱硫塔の上部からの一次脱硫処理ガスを前記二次脱硫工程に送給し、
前記生物脱硫塔の原ガスの通ガス速度がＳＶ１０〜２０ｈｒ −１ で、散水量が液ガス比として０．４〜０．８であり、
前記二次脱硫工程において、内部に充填材層が設けられており、また、この充填材層に散水するアルカリ吸収液の散水ノズルが設けられているアルカリ吸収塔に前記一次脱硫処理ガスを導入してアルカリ吸収液と向流接触させ、
前記アルカリ吸収液が、ｐＨ８〜１３の苛性ソーダ水溶液又は苛性カリ水溶液であり、前記アルカリ吸収塔の通ガス速度がＳＶ５０〜２００ｈｒ −１ で、液ガス比が０．０１〜０．２であり、
前記二次脱硫工程から排出される処理ガスの硫化水素濃度が５０ｐｐｍ以下であることを特徴とする硫化水素含有ガスの脱硫方法。A primary desulfurization step in which raw gas containing hydrogen sulfide is brought into contact with activated sludge treated water to roughly remove hydrogen sulfide in the raw gas;
A secondary desulfurization step of removing hydrogen sulfide remaining in the gas by contacting the treatment gas of the primary desulfurization step with an alkali in a wet or dry manner,
In the primary desulfurization step, 80 to 95% of the hydrogen sulfide in the raw gas is removed to obtain a primary desulfurization treatment gas having a hydrogen sulfide concentration of 100 to 500 ppm, which is supplied to the secondary desulfurization step to obtain a secondary A method for desulfurizing a hydrogen sulfide-containing gas to be desulfurized,
In the primary desulfurization step, a filler layer carrying microorganisms that oxidatively decompose hydrogen sulfide is provided inside, and a water spray nozzle for sprinkling activated sludge treated water is provided above the filler layer. the raw gas is introduced, to deliver primary desulfurized gas from the top of the organism desulfurization tower to the secondary desulfurization step in the lower part of the biological desulfurization tower attached to,
The gas flow rate of the raw gas in the biological desulfurization tower is SV10 to 20 hr −1 , and the amount of water spray is 0.4 to 0.8 as the liquid gas ratio.
In the secondary desulfurization step, the primary desulfurization treatment gas is introduced into an alkali absorption tower in which a filler layer is provided, and in which a water spray nozzle of an alkali absorbent that sprays the filler layer is provided. In countercurrent contact with the alkali absorbent,
The alkali absorbing solution is a caustic soda aqueous solution or a caustic potash aqueous solution having a pH of 8 to 13, the gas passing speed of the alkali absorbing tower is SV50 to 200 hr −1 , and the liquid gas ratio is 0.01 to 0.2,
A method for desulfurizing a hydrogen sulfide-containing gas hydrogen sulfide concentration in the treated gas discharged from the secondary desulfurization process is characterized in der Rukoto below 50 ppm.
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| KR100864426B1 (en) * | 2002-09-03 | 2008-10-20 | 주식회사 포스코 | Method of removing H2S from Coke Oven Gas |
| JP2006116381A (en) * | 2004-10-19 | 2006-05-11 | Kazuaki Tamatsubo | Method and apparatus for methane-fermenting organic waste water |
| JP4862314B2 (en) * | 2005-08-05 | 2012-01-25 | 栗田工業株式会社 | Method and apparatus for desulfurization of gas containing hydrogen sulfide |
| JP5352079B2 (en) * | 2007-11-27 | 2013-11-27 | Ｊｆｅエンジニアリング株式会社 | Biodesulfurization apparatus and method for digestion gas |
| JP2011235234A (en) * | 2010-05-10 | 2011-11-24 | Ihi Corp | Desulfurizer and desulfurization method |
| US8846381B2 (en) * | 2011-04-21 | 2014-09-30 | Beijing Helee Bio-Energy Technology Co., Ltd. | Biogas desulfurization device |
| CN102350203A (en) * | 2011-09-20 | 2012-02-15 | 中国石油化工集团公司 | Process for removing hydrogen-sulfide-containing gas by using rotary power equipment |
| CN104031709A (en) * | 2014-05-26 | 2014-09-10 | 沈阳航空航天大学 | Methane micro-aerobic wet-type ammonia desulphurization device |
| KR101566643B1 (en) | 2014-12-24 | 2015-11-10 | 에이티이 주식회사 | Foul odor eliminating device |
| CN108636065B (en) * | 2018-06-28 | 2023-11-14 | 珠海恒基达鑫国际化工仓储股份有限公司 | Exhaust gas desulfurization and deodorization device |
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| JPH05115742A (en) * | 1991-09-18 | 1993-05-14 | Nippon Gesuidou Jigyodan | Biological deodorizing apparatus |
| JPH0929214A (en) * | 1995-07-21 | 1997-02-04 | Nitto Boseki Co Ltd | Garbage treatment apparatus |
| JPH1099641A (en) * | 1996-09-25 | 1998-04-21 | Fuso Unitec Kk | Desulfurization of digestion gas and desulfurizing device |
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