JP2004085300A

JP2004085300A - Gas sample gathering method and gathering apparatus

Info

Publication number: JP2004085300A
Application number: JP2002245019A
Authority: JP
Inventors: Toshio Tsukamoto; 塚本　敏男; Akihiro Arikawa; 有川　彰浩
Original assignee: Ebara Corp
Current assignee: Ebara Corp
Priority date: 2002-08-26
Filing date: 2002-08-26
Publication date: 2004-03-18
Anticipated expiration: 2022-08-26
Also published as: JP3778442B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sample gas gathering method and a sample gas gathering apparatus for accurately and easily capturing constituents to be analyzed contained in gas without any loss even in the case of a wet gas where the gas sample contains much moisture. <P>SOLUTION: In the sample gathering method of gas for analyzing constituents contained in the wet gas, the wet gas is cooled to a temperature below a freezing point in a wide passage for coagulating the moisture in gas. A first absorption means for capturing the target constituent in gas, and a second absorption means for capturing the target constituent that is not captured by the first absorption means under temperature conditions below the freezing point are used, thus completely capturing the target constituent in the wet gas. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、ガス試料採取方法及び採取装置に関し、さらに詳しくは、湿りガス中の水分の影響を受けることなく、分析対象成分を、損失なく、正確に捕集できるガス試料採取方法及び採取装置に関する。
【０００２】
【従来の技術】
煙道、煙突、ダクトに排出される排ガス中の特定ガス状成分を分析する場合、吸収液を入れた吸収瓶に試料ガスを導入して、特定ガス状成分を吸収液中に捕集し、分析用試料溶液とすることが行なわれている（日本工業規格Ｋ００９５−１９９９「排ガス試料採取方法」）。
図３に示すように、吸収瓶１には、吸収液３を入れ、ガス導入管２より吸収液３に試料ガスを導入する構造となっており、吸収瓶の出口の先には、流量調整器７、吸引ポンプ８、ガスメーター９等が順次接続されている。なお、図３において、吸収瓶が２段に設けられている形式で、４は後段吸収瓶、５は後段吸収瓶のガス導入管、６はガス試料である。
【０００３】
このような従来の装置において、分析対象成分を損失なく、正確に捕集するために次のような対策がとられている。
（１）吸収瓶を直列多段に接続する。
（２）吸収瓶を冷却槽又は冷却室に入れて冷却する。
【０００４】
【発明が解決しようとする課題】
上述の対策は、分析対象成分の捕集性能を上げるのに有効であり、直列に接続する吸収瓶の数を増やすほど、また、吸収液の温度を下げるほど捕集効率は高くなる。しかしながら、捕集性能を上げるために吸収瓶の数を増やせば、装置が過大になるばかりでなく、大量の吸収液が必要になること、採取作業や分析作業が複雑になることなど問題点が多い。一方、吸収液の温度を下げることで、少ない吸収瓶の数で高い捕集性能を発揮することが可能であるものの、実際には、氷浴程度の冷却温度では捕集が不十分な場合が多く、ドライアイスなどを用いてより低温まで冷却することが望ましい。ドライアイスによる冷却は、ガス試料が乾燥ガスの場合は、従来の捕集方法及び捕集装置で問題なく実施できるものの、ガス試料が多量のミストや水蒸気を含んだ湿りガスの場合は、吸収瓶内、特にガス導入配管内等の狭い流路において水分が凝固して閉塞し、ガスの導入が不可能になってしまうという致命的な問題があった。
【０００５】
従来、このような問題がある場合は、吸収瓶の前段に、塩化カルシウムや過塩素酸マグネシウム等の除湿剤を用いた除湿手段を設けて対応するのが一般的であるが、この方法は、対象成分の吸収手段の他に別途除湿手段が必要なため、試料採取装置及び採取方法を複雑にする間題があった。また、対象成分の中には、水分とともに除湿剤に捕捉されてしまうものも多く、除湿剤に捕捉された成分の回収は容易でないため、定量分析におけるマイナス誤差要因になるという大きな間題があった。一方、除湿剤に捕捉されにくい成分の場合も、捕捉されないことを確認するための予備的な検証が不可欠であり、手間のかかる方法であった。
【０００６】
本発明は、上記の事情に鑑みてなされたもので、ガス試料が湿りガスであっても、ガス中に含まれる分析対象成分を損失無く正確に、しかも簡便に捕集できる試料ガス採取方法及び装置を提供することを課題とする。
【０００７】
【課題を解決するための手段】
本発明は、下記の手段により上記課題を解決することができた。
（１）湿りガス中に含まれる成分を分析するための前記ガスの試料採取方法において、湿りガスを広い通路で氷点以下に冷却しながらガス中の水分を凝固させると共にガス中の対象成分を捕集する第１の吸収手段と、該第１の吸収手段で捕集しきれなかった対象成分を氷点以下の温度条件で捕集する第２の吸収手段を使用して湿りガス中の対象成分を完全に捕集することを特徴とするガス試料の採取方法。
【０００８】
（２）湿りガス中に含まれる成分を分析するための前記ガスの試料採取装置において、ガスの吸引手段と、ガスを広い通路で氷点以下に冷却し、ガス中の水分を凝固させると共にガス中の対象成分を捕集する第１の吸収部と、該第１の吸収部からのガスを導入し、氷点以下の温度条件として、第１の吸収部で捕集しきれなかった対象成分を捕集する第２の吸収部から構成されることを特徴とするガス試料の採取装置。
【０００９】
（３）前記第１の吸収部は、ガス流路が、ガスを氷点以下に冷却しても凝固した水分によるガス流路の閉塞が生じないように構成されており、かつ、前記第２の吸収部は、ガス及び吸収媒体を氷点以下に冷却しながら、ガスと吸収媒体とが接触できるように構成されていることを特徴とする前記（２）記載のガス試料の採取装置。
（４）前記第１及び第２の吸収部として共に吸収瓶を用い、第１の吸収部で用いる吸収瓶の試料ガス導入部の管径が、第２の吸収部で用いる吸収瓶の試料ガス導入部の管径よりも大きいことを特徴とする前記（３）記載のガス試料の採取装置。
（５）前記第１及び第２の吸収部として共に吸収瓶を用い、ガスの流れ方向に対して、第１の吸収部で用いる吸収瓶を逆方向に、かつ、第２の吸収部で用いる吸収瓶を順方向に接続して構成されていることを特徴とする前記（３）記載のガス試料の採取装置。
【００１０】
さらに、本発明の装置において、好ましい態様は以下のとおりである。
（６）前記第１の吸収部の導入管の径は１０ミリ以上であり、第２の吸収部が汎用されている吸収性能の高い吸収瓶であることを特徴とする前記（２）記載のガス試料の採取装置。
【００１１】
このように、吸収瓶のような吸収装置の構造を、湿りガス中の水分が凝固・付着してもガス流路が閉塞しないように工夫することによって、低温の冷浴を用いて対象成分の捕集効率を上げることができ、その結果、吸収瓶の数を削減することができるため、極めて簡便な装置で容易にガス試料の採取が高い効率で行うことができる。
【００１２】
次に、本発明の内容について、詳細に説明する。
吸収瓶などのガス導入管径（内径）は、小さすぎると通気抵抗が増えるとともに、ガス中に含まれる固型分などにより閉塞する危険性がある。逆に、管径が大きすぎると、吸収液と吸収液中に導入されるガスの接触が悪くなり、対象成分の捕集効率が低下する懸念があるため、一般的には、管径が数ミリから１０数ミリの管が用いられる。しかしながら、このような管径の場合、氷点以下の温度条件で、多量のミストや水蒸気を含んだ湿りガスを長時間にわたって導入すると、管内に凝固した水分が蓄積して閉塞する。したがって、ガスの水蒸気量やガスの導入時間にもよるが、本発明の第１の吸収手段における吸収瓶（以下、前段吸収瓶と称する）では、ガス導入管の径は１０ミリ以上であることが好ましく、２０ミリ以上であることがさらに好ましい。このように管径を大きくすると、凝固した水分が蓄積しても閉塞する危険性は減る反面、前述のとおり、試料ガスと吸収液との接触効率が悪くなる。
【００１３】
しかし、本発明者等のこれまでの実際の経験から、試料ガスと吸収液との接触効率を多少犠牲にしても、氷点以下の低温条件に維持することで、高い捕集性能を発揮できる場合が多いことが分かった。仮に、前段吸収瓶において高い捕集性能が得られない場合でも、本発明における前段吸収瓶の最も重要な役割は、ガス中の水分を凝固させて除去することであるため、対象成分の捕集効率はさして大きな問題とはならない。前段吸収瓶において捕集しきれなかった対象成分は第２の吸収手段（以下、後段吸収瓶と称する）に導入されるのであるが、ガス中に含まれていた水分の殆どは前段吸収瓶において既に除去されているため、後段吸収瓶では、水分の凝固による流路閉塞の懸念がない。したがって、一般的に汎用されている吸収性能の高い吸収瓶を用いて、氷点以下の低温に冷却しながら、ガス試料採取を行うことができる。
【００１４】
前段吸収瓶と後段吸収瓶が１本づつの計２本直列方式で満足な試料採取ができない場合は、前段吸収瓶又は／及び後段吸収瓶を必要に応じて追加して多段に接続すれば良い。前段吸収瓶の接続本数は、ガス中の水分の除去性能をもとに決めれば良いし、後段吸収瓶の接続本数は、対象成分の捕集性能をもとに決めれば良い。
【００１５】
本発明では必ずしも吸収媒体中にガスを導入する必要はない。例えば、何も入れない吸収瓶を単に低温冷却してガス試料を導入し、対象成分を一旦吸収瓶の内壁等に付着させ、ガス試料の導入終了とともに少量の吸収液などで瓶内液を洗浄することによって対象成分の試料溶液とすることもできる。また、吸収媒体を用いる場合は、媒体の種類に特に制限はなく、液体であっても、又は、例えばビーズ状の固体のようなものでも良い。このため、本発明でいう「吸収媒体」は狭義の吸収のみを行なうものに限られず、吸着を行なう固体の媒体も含むものである。液体の場合は、ガスの通気を妨げないものであれば冷浴によって試料採取中に凝固してしまうものでも良いが、凝固しないものの方が好ましい。
【００１６】
本発明は、水の凝固によるガス流路の閉塞が生じないようになされたものであるから、冷却温度の制限がないため、種々の冷媒を使用することができる。凝固点降下させた水やドライアイス等はもちろんのこと、吸収装置が冷却温度に耐えられるものであれば、液体酸素、液体アルゴン、液体窒素などを用いることも可能である。ただ、ガス中の対象成分及び共存成分が液化あるいは凝固するような温度とすると、ガス流路の閉塞が生じたり、捕集がかたよって不十分となるので、好ましくない。
【００１７】
本発明の方法を最も簡単に実施するには、前段吸収瓶と後段吸収瓶のどちらも汎用されている吸収瓶を用い、ガスの流れ方向に対して前段吸収瓶は逆方向に、後段吸収瓶は順方向に接続してガス試料採取装置を構成すれば良い。前段吸収瓶を逆方向に接続することにより、ガスは吸収瓶底面近くの冷却された細い導入配管を経由せずに直接吸収瓶本体内に導入される。すなわち、ガスが最初に冷却される流路はガス導入管内ではなく、ガス導入管外若しくは吸収瓶本体内の広い流路であり、ガス中の水分は、吸収瓶本体の内壁やガス導入管の外壁面に付着する。その後、ガスはもともとガス導入部であった細い配管内を逆向きに流れて前段吸収瓶から排出されるのであるが、この時点では、既にガスは除湿されているため、導入管内が凝固した水分の蓄積によって閉塞することはない。この方法では、前段吸収瓶において吸収液中に試料ガスを吹き込むことは難しいものの（細い配管の下端が吸収液中に浸かっていると、細い配管から流出する試料ガスにより吸収液が細い配管を通って後吸収瓶へ流出してしまうため）、前述のとおり、極めて低い温度条件であるため吸収液を用いなくても、水分と共に対象成分の殆どが吸収瓶内に捕集される。このような形で水分と共に捕集された成分は、ガス採取終了後、低温条件のまま、後段吸収瓶の吸収液と同じ種類の吸収液で前段吸収瓶内を洗浄し、この洗浄液を後段吸収瓶中の吸収液と併せて試料溶液として分析に供せばよい。
【００１８】
【発明の実施の形態】
以下に、本発明を図面を参照して詳細に説明する。図３で示した構成要素と同一構成要素は同一符号を用いて示す。
図１は、本発明のガス試料採取装置の一例を示す模式図である。
ガス試料採取装置は前段吸収瓶１、後段吸収瓶４、流量調整計７、吸引ポンプ８、ガスメーター９が直列に接続された構成である。前段吸収瓶１、後段吸収瓶４中は冷却槽１１で冷却され、各吸収瓶中には吸収液３が入っている。前段吸収瓶１のガス導入管２は、ガス中の水分の凝固による流路の閉塞を防止するため、径の大きいものを用いている。ガス試料６は、吸引ポンプ８によって、まず前段吸収瓶１に導入され、瓶中もしくは吸収液３中でガス中の水分と分析対象成分が吸収される。ついで、後段吸収瓶４に導入され、前段吸収瓶１で捕集しきれなかった分析対象成分が後段吸収瓶４の吸収液３に捕集される。なお、図１において、１０は冷媒である。
【００１９】
図２は、本発明のガス試料採取装置の別の一例を示す模式図である。
ガス試料採取装置は前段吸収瓶１、後段吸収瓶４、流量調整計７、吸引ポンプ８、ガスメーター９が直列に接続された構成である。前段吸収瓶１、後段吸収瓶４中は冷却槽１１で冷却され、吸収液３は後段吸収瓶４にのみ入っている。前段吸収瓶１は、ガス中の水分の凝固による流路の閉塞を防止するため、ガスの流れ方向に対して逆向きに設置されている。このため、前段吸収瓶１におけるガス導入管２Ａは細くて短く、吸収瓶１内には吸収液３が入っていないこともあって、ガス試料が吸収液３内に吹き込まれることはない。湿りガスのガス試料６は、吸引ポンプ８によって、まず前段吸収瓶１に導入され、瓶１中でガス試料６中の水分と分析対象成分が吸収される。ついで、後段吸収瓶４に導入され、前段吸収瓶１で捕集しきれなかった分析対象成分が後段吸収瓶４の吸収液３に捕集される。
【００２０】
【実施例】
以下、本発明を実施例により具体的に説明するが、本発明はこれらの実施例に限定されない。
【００２１】
実施例１
図１に示すガス試料採取装置を用いて、嫌気性消化ガス中に含まれる微量成分（シロキサン類）を捕集し、ガスクロマトグラフ質量分析計を用いて定量分析した。ガスの性状、ガス採取条件は次のとおりである。
【００２２】

【００２３】
消化ガス中のシロキサン濃度を第１表に示す。
【００２４】
実施例２
図２に示すガス試料採取装置を用いたこと以外は、実施例１と同じ条件で嫌気性消化ガス中に含まれるシロキサン類を捕集し、定量分析した。吸収瓶のガス導入管径（内径）は６ｍｍ（２Ａ、５共に）である。（比較例１も同じ）
消化ガス中のシロキサン濃度を第１表に示す。
【００２５】
比較例１
冷媒として氷を用いた他は、実施例１と同じ条件で嫌気性消化ガス中に含まれるシロキサン類を捕集し、定量分析した。
消化ガス中のシロキサン濃度を第１表に示す。シロキサン濃度は実施例１及び実施例２に比べて低かった。
【００２６】
比較例２
前段吸収瓶に後段吸収瓶と同じものを用いた以外は、実施例１と同じ条件で嫌気性消化ガス中に含まれるシロキサン類を捕集し、定量分析した。
消化ガスの試料採取開始直後から、前段吸収瓶のガス試料導入管内に水分が凝固・付着した。３０分程度経過時点で前段吸収瓶の通気抵抗が上昇し始め、１時間経過時点で完全に流路が閉塞し、ガス採取が不可能になった。
【００２７】
【表１】

【００２８】
【発明の効果】
本発明に係るガス試料採取方法及び装置によれば、ガス試料中に大量の水分が含まれている場合でも吸収瓶の構造を、水分の凝固によってガス導入管内が閉塞しないように工夫しているため、氷点以下の低温の冷浴を用いて分析対象成分の捕集効率を上げることができ、その結果、吸収瓶の数を削減することができるため、極めて簡便な装置で、容易に試料ガス中に含まれる成分を、損失なく、正確に捕集できる。
【図面の簡単な説明】
【図１】本発明のガス試料採取装置の一例を示す模式図。
【図２】本発明のガス試料採取装置の別の例を示す模式図。
【図３】従来のガス試料採取装置の例を示す模式図。
【符号の説明】
１　　前段吸収瓶
２　　ガス導入管
２Ａ　ガス導入管
３　　吸収液
４　　後段吸収瓶
５　　ガス導入管
６　　試料ガス
７　　流量調整器
８　　吸引ポンプ
９　　ガスメーター
１０　　冷媒
１１　　冷却槽[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a gas sampling method and a gas sampling apparatus, and more particularly, to a gas sampling method and a gas sampling apparatus capable of accurately collecting a component to be analyzed without being affected by moisture in a humid gas, without loss. .
[0002]
[Prior art]
When analyzing specific gaseous components in flue gas discharged from stacks, chimneys, and ducts, sample gas is introduced into the absorption bottle containing the absorption liquid, and the specific gaseous components are collected in the absorption liquid. It is used as a sample solution for analysis (Japanese Industrial Standard K0095-1999 "Exhaust gas sampling method").
As shown in FIG. 3, the absorption bottle 1 is filled with the absorption liquid 3, and the sample gas is introduced into the absorption liquid 3 from the gas introduction pipe 2. The flow rate is adjusted at the end of the outlet of the absorption bottle. The device 7, the suction pump 8, the gas meter 9, etc. are connected in order. In FIG. 3, the absorption bottle is provided in two stages, 4 is the latter absorption bottle, 5 is the gas introduction pipe of the latter absorption bottle, and 6 is the gas sample.
[0003]
In such a conventional apparatus, the following countermeasures are taken to accurately collect the components to be analyzed without loss.
(1) Connect the absorption bottles in series and multiple stages.
(2) Put the absorption bottle in a cooling tank or a cooling chamber and cool it.
[0004]
[Problems to be solved by the invention]
The above countermeasures are effective in improving the collection performance of the components to be analyzed. The more the number of absorption bottles connected in series and the lower the temperature of the absorption liquid, the higher the collection efficiency. However, if the number of absorption bottles is increased to improve the collection performance, not only will the device become excessively large, but also a large amount of absorbing liquid will be required, and the collection and analysis operations will be complicated. Many. On the other hand, by lowering the temperature of the absorbing solution, it is possible to exhibit high collecting performance with a small number of absorbing bottles, but in reality, collecting may be insufficient at a cooling temperature similar to an ice bath. It is often desirable to cool to lower temperatures using dry ice or the like. Cooling with dry ice can be carried out without problems using conventional collection methods and devices when the gas sample is a dry gas.However, when the gas sample is a wet gas containing a large amount of mist or water vapor, use an absorption bottle. In particular, there is a fatal problem that water is solidified and blocked in a narrow flow path such as in a gas introduction pipe, so that gas cannot be introduced.
[0005]
Conventionally, when there is such a problem, it is common to provide a dehumidifying means using a dehumidifying agent such as calcium chloride or magnesium perchlorate in a stage preceding the absorption bottle, but this method is generally used. Since a separate dehumidifying means is required in addition to the means for absorbing the target component, there is a problem that the sampling device and the sampling method are complicated. In addition, many of the target components are trapped by the dehumidifier together with moisture, and it is not easy to recover the components trapped by the dehumidifier, which poses a major problem that it becomes a negative error factor in quantitative analysis. Was. On the other hand, in the case of a component that is difficult to be trapped by the dehumidifier, preliminary verification for confirming that the component is not trapped is indispensable, which is a time-consuming method.
[0006]
The present invention has been made in view of the above circumstances, and even if the gas sample is a wet gas, the analyte component contained in the gas can be accurately collected without loss, and can be easily collected. It is an object to provide a device.
[0007]
[Means for Solving the Problems]
The present invention has solved the above problems by the following means.
(1) In the gas sampling method for analyzing components contained in a wet gas, the wet gas is cooled to a freezing point or below a free passage in a wide passage to solidify moisture in the gas and to capture a target component in the gas. A first absorbing means for collecting, and a second absorbing means for collecting, at a temperature below the freezing point, target components that cannot be completely collected by the first absorbing means. A method for collecting a gas sample, wherein the gas sample is completely collected.
[0008]
(2) In the gas sampling apparatus for analyzing components contained in the wet gas, the gas suction means and the gas are cooled to below freezing in a wide passage to solidify the moisture in the gas and to remove the gas from the gas. A first absorption section for collecting the target component, and a gas from the first absorption section, and the target component that could not be completely collected by the first absorption section is collected under a temperature condition of not more than the freezing point. An apparatus for collecting a gas sample, comprising: a second absorption unit for collecting gas.
[0009]
(3) The first absorption section is configured such that the gas flow path does not block the gas flow path due to solidified moisture even when the gas is cooled to a temperature below the freezing point. The gas sample collecting apparatus according to (2), wherein the absorbing unit is configured to allow the gas and the absorbing medium to come into contact with each other while cooling the gas and the absorbing medium to a temperature below the freezing point.
(4) An absorption bottle is used as both the first and second absorption sections, and the diameter of the sample gas introduction section of the absorption bottle used in the first absorption section is equal to the sample gas of the absorption bottle used in the second absorption section. The gas sample collecting device according to the above (3), wherein the gas sample is larger than the pipe diameter of the introduction part.
(5) An absorption bottle is used as both the first and second absorbers, and the absorption bottle used in the first absorber is used in the direction opposite to the gas flow direction and used in the second absorber. The gas sample collecting apparatus according to the above (3), wherein the gas sampling apparatus is configured by connecting an absorption bottle in a forward direction.
[0010]
Further, in the apparatus of the present invention, preferred embodiments are as follows.
(6) The diameter of the introduction pipe of the first absorption section is 10 mm or more, and the second absorption section is a general-purpose absorption bottle having high absorption performance, which is described in (2). Gas sampling device.
[0011]
In this way, by devising the structure of an absorption device such as an absorption bottle so that the gas flow path does not become blocked even when the moisture in the wet gas solidifies or adheres, the target component can be cooled using a low-temperature cold bath. Since the collection efficiency can be increased, and as a result, the number of absorption bottles can be reduced, a gas sample can be easily collected with a very simple device at a high efficiency.
[0012]
Next, the contents of the present invention will be described in detail.
If the gas introduction pipe diameter (inner diameter) of the absorption bottle or the like is too small, the gas flow resistance increases, and there is a risk of clogging due to solid components contained in the gas. Conversely, if the pipe diameter is too large, contact between the absorbing solution and the gas introduced into the absorbing solution becomes poor, and there is a concern that the collection efficiency of the target component may be reduced. Millimeters to several dozen millimeter tubes are used. However, in the case of such a pipe diameter, when a humid gas containing a large amount of mist or water vapor is introduced over a long period of time at a temperature below the freezing point, solidified moisture accumulates in the pipe and the pipe is blocked. Therefore, depending on the amount of gaseous water vapor and the gas introduction time, the diameter of the gas introduction pipe should be 10 mm or more in the absorption bottle (hereinafter referred to as the pre-stage absorption bottle) in the first absorption means of the present invention. Is more preferable, and more preferably 20 mm or more. Increasing the pipe diameter in this way reduces the risk of blockage even if solidified water accumulates, but decreases the contact efficiency between the sample gas and the absorbing liquid as described above.
[0013]
However, from the actual experience of the present inventors, it has been found that, even if the efficiency of contact between the sample gas and the absorbing solution is somewhat sacrificed, high collection performance can be exhibited by maintaining the temperature at a low temperature below the freezing point. It turned out that there were many. Even if a high absorption performance cannot be obtained in the first-stage absorption bottle, the most important role of the first-stage absorption bottle in the present invention is to coagulate and remove the moisture in the gas, so that the collection of the target component is performed. Efficiency is not a major issue. The target components that could not be collected in the first-stage absorption bottle are introduced into the second absorption means (hereinafter, referred to as the second-stage absorption bottle), but most of the water contained in the gas is removed by the first-stage absorption bottle. Since it has already been removed, there is no fear of blockage of the flow path due to coagulation of moisture in the latter absorption bottle. Therefore, gas sampling can be performed while cooling to a low temperature below the freezing point using an absorption bottle that is generally used and has high absorption performance.
[0014]
If it is not possible to obtain a satisfactory sample in a two-series system with one front-stage absorption bottle and one rear-stage absorption bottle, a front-stage absorption bottle and / or a rear-stage absorption bottle may be added and connected in multiple stages as necessary. . The number of connected front-stage absorption bottles may be determined based on the performance of removing moisture in the gas, and the number of connected rear-stage absorption bottles may be determined based on the performance of collecting the target component.
[0015]
In the present invention, it is not always necessary to introduce a gas into the absorbing medium. For example, an absorption bottle in which nothing is put is simply cooled at a low temperature to introduce a gas sample, and the target component is once adhered to the inner wall of the absorption bottle, and the bottle solution is washed with a small amount of the absorption solution when the introduction of the gas sample is completed. By doing so, a sample solution of the target component can be obtained. When an absorbing medium is used, the type of the medium is not particularly limited, and may be a liquid or a solid such as a bead. For this reason, the "absorbing medium" in the present invention is not limited to a medium that only performs absorption in a narrow sense, but also includes a solid medium that performs adsorption. In the case of a liquid, as long as it does not hinder gas ventilation, it may be solidified during the sampling by a cold bath, but is preferably non-coagulated.
[0016]
In the present invention, since the gas flow path is not blocked by solidification of water, there is no limitation on the cooling temperature, so that various refrigerants can be used. Liquid oxygen, liquid argon, liquid nitrogen, and the like can be used as long as the absorption device can withstand the cooling temperature, as well as water or dry ice whose freezing point has been lowered. However, it is not preferable that the temperature is such that the target component and the coexisting component in the gas are liquefied or coagulated, because the gas flow path is blocked or the trapping becomes insufficient.
[0017]
In order to carry out the method of the present invention in the simplest manner, both the first-stage absorption bottle and the second-stage absorption bottle use a commonly used absorption bottle, and the first-stage absorption bottle is in the opposite direction to the gas flow direction, and the second-stage absorption bottle is used. May be connected in the forward direction to form a gas sampling device. By connecting the pre-stage absorption bottle in the reverse direction, the gas is directly introduced into the absorption bottle main body without passing through the cooled thin introduction pipe near the bottom surface of the absorption bottle. That is, the flow path where the gas is cooled first is not inside the gas introduction pipe, but a wide flow path outside the gas introduction pipe or inside the absorption bottle main body, and the moisture in the gas is caused by the inner wall of the absorption bottle main body and the gas introduction pipe. Attaches to outer wall. After that, the gas flows in the narrow pipe, which was originally the gas inlet, in the opposite direction and is discharged from the pre-absorption bottle, but at this point, the gas has already been dehumidified, and the water inside the inlet pipe has solidified. Will not be blocked by the accumulation of In this method, it is difficult to inject the sample gas into the absorbing solution in the pre-absorption bottle. As described above, since the temperature is extremely low, most of the target components are collected in the absorption bottle together with the moisture without using an absorbing liquid. After the gas is collected, the components collected together with the water are washed in the former absorption bottle with the same type of absorption liquid as the absorption liquid in the latter absorption bottle after the end of gas sampling and kept in a low temperature condition. What is necessary is just to provide it for analysis as a sample solution together with the absorption liquid in a bottle.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings. The same components as those shown in FIG. 3 are denoted by the same reference numerals.
FIG. 1 is a schematic diagram showing an example of the gas sampling device of the present invention.
The gas sampling apparatus has a configuration in which a front-stage absorption bottle 1, a rear-stage absorption bottle 4, a flow controller 7, a suction pump 8, and a gas meter 9 are connected in series. The inside of the first absorption bottle 1 and the second absorption bottle 4 is cooled by the cooling tank 11, and the absorption liquid 3 is contained in each absorption bottle. The gas inlet pipe 2 of the first-stage absorption bottle 1 has a large diameter in order to prevent the flow path from being blocked by coagulation of moisture in the gas. The gas sample 6 is first introduced into the pre-stage absorption bottle 1 by the suction pump 8, and the water and the analysis target component in the gas are absorbed in the bottle or the absorption liquid 3. Next, the components to be analyzed that have been introduced into the second-stage absorption bottle 4 and have not been collected in the first-stage absorption bottle 1 are collected in the absorption liquid 3 of the second-stage absorption bottle 4. In FIG. 1, reference numeral 10 denotes a refrigerant.
[0019]
FIG. 2 is a schematic diagram showing another example of the gas sampling device of the present invention.
The gas sampling apparatus has a configuration in which a front-stage absorption bottle 1, a rear-stage absorption bottle 4, a flow controller 7, a suction pump 8, and a gas meter 9 are connected in series. The inside of the first-stage absorption bottle 1 and the second-stage absorption bottle 4 is cooled by the cooling tank 11, and the absorption liquid 3 is contained only in the second-stage absorption bottle 4. The pre-stage absorption bottle 1 is installed in a direction opposite to the gas flow direction in order to prevent the flow path from being blocked by coagulation of moisture in the gas. For this reason, the gas introduction pipe 2A in the former absorption bottle 1 is thin and short, and the absorption liquid 3 is not contained in the absorption bottle 1, so that the gas sample is not blown into the absorption liquid 3. The gas sample 6 of the wet gas is first introduced into the pre-absorption bottle 1 by the suction pump 8, and the water and the analysis target component in the gas sample 6 are absorbed in the bottle 1. Next, the components to be analyzed that have been introduced into the second-stage absorption bottle 4 and have not been collected in the first-stage absorption bottle 1 are collected in the absorption liquid 3 of the second-stage absorption bottle 4.
[0020]
【Example】
Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited to these Examples.
[0021]
Example 1
Trace components (siloxanes) contained in the anaerobic digestion gas were collected using the gas sampling device shown in FIG. 1 and quantitatively analyzed using a gas chromatograph mass spectrometer. Gas properties and gas sampling conditions are as follows.
[0022]

[0023]
Table 1 shows the siloxane concentration in the digested gas.
[0024]
Example 2
The siloxanes contained in the anaerobic digestion gas were collected and quantitatively analyzed under the same conditions as in Example 1 except that the gas sampling device shown in FIG. 2 was used. The gas inlet tube diameter (inner diameter) of the absorption bottle is 6 mm (2A, 5 both). (The same applies to Comparative Example 1)
Table 1 shows the siloxane concentration in the digested gas.
[0025]
Comparative Example 1
Siloxane contained in the anaerobic digestion gas was collected and quantitatively analyzed under the same conditions as in Example 1 except that ice was used as the refrigerant.
Table 1 shows the siloxane concentration in the digested gas. The siloxane concentration was lower than in Examples 1 and 2.
[0026]
Comparative Example 2
Siloxane contained in the anaerobic digestion gas was collected and quantitatively analyzed under the same conditions as in Example 1 except that the same absorbent bottle as the former absorbent bottle was used.
Immediately after the start of digestion gas sampling, moisture solidified and adhered to the gas sample introduction pipe of the pre-absorption bottle. About 30 minutes later, the ventilation resistance of the pre-absorption bottle began to increase, and after one hour, the flow path was completely blocked, and gas sampling became impossible.
[0027]
[Table 1]

[0028]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to the gas sampling method and apparatus which concerns on this invention, even if a gas sample contains a large amount of water, the structure of an absorption bottle is devised so that the inside of a gas introduction pipe may not be blocked by solidification of water. Therefore, it is possible to increase the collection efficiency of the component to be analyzed by using a low-temperature cold bath having a temperature below the freezing point, and as a result, it is possible to reduce the number of absorption bottles. The components contained therein can be accurately collected without loss.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an example of a gas sampling device according to the present invention.
FIG. 2 is a schematic view showing another example of the gas sampling apparatus of the present invention.
FIG. 3 is a schematic view showing an example of a conventional gas sampling device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 First-stage absorption bottle 2 Gas introduction pipe 2A Gas introduction pipe 3 Absorbent 4 Rear-stage absorption bottle 5 Gas introduction pipe 6 Sample gas 7 Flow controller 8 Suction pump 9 Gas meter 10 Refrigerant 11 Cooling tank

Claims

The gas sampling method for analyzing a component contained in a wet gas, wherein the wet gas is cooled to a freezing point or below a wide passage while solidifying water in the gas and collecting a target component in the gas. The target component in the humid gas is completely captured by using the first absorption unit and the second absorption unit that collects the target component that cannot be completely collected by the first absorption unit at a temperature below the freezing point. A method for collecting a gas sample, comprising collecting the sample.

In the gas sampling apparatus for analyzing the components contained in the wet gas, the gas sampling means and the gas are cooled to below freezing in a wide passage to solidify the moisture in the gas and to remove the target component in the gas. A first absorbing section for collecting gas, and a gas for introducing the gas from the first absorbing section and setting a temperature condition below the freezing point to collect target components that cannot be completely collected by the first absorbing section. An apparatus for collecting a gas sample, comprising: two absorption units.

The first absorption section is configured such that the gas flow path does not block the gas flow path due to solidified moisture even if the gas is cooled to a temperature below the freezing point, and the second absorption section 3. The gas sample collecting apparatus according to claim 2, wherein the gas and the absorbing medium are brought into contact with each other while cooling the gas and the absorbing medium to below the freezing point.

An absorption bottle is used as both the first and second absorption sections, and the diameter of the sample gas introduction section of the absorption bottle used in the first absorption section is the same as that of the sample gas introduction section of the absorption bottle used in the second absorption section. 4. The gas sample collecting device according to claim 3, wherein the gas sample is larger than the pipe diameter.

An absorption bottle is used as the first and second absorption units, and the absorption bottle used in the first absorption unit is reversed in the direction of gas flow, and the absorption bottle used in the second absorption unit is used. The gas sample collection device according to claim 3, wherein the gas sample collection device is configured to be connected in a forward direction.