JP3581754B2

JP3581754B2 - Method and apparatus for determining moisture in high-purity gas

Info

Publication number: JP3581754B2
Application number: JP06212296A
Authority: JP
Inventors: 正憲猪子; 健司林
Original assignee: Tsurumi Soda Co Ltd
Current assignee: Tsurumi Soda Co Ltd
Priority date: 1996-02-23
Filing date: 1996-02-23
Publication date: 2004-10-27
Anticipated expiration: 2016-02-23
Also published as: JPH09229885A

Description

【０００１】
【発明の属する技術分野】
本発明は高純度ガス中の水分の定量方法及びその装置に関する。
【０００２】
【従来の技術】
例えば無水塩化水素ガス等の高純度ガス中の水分の定量方法の１つに露点法が知られている。この方法は高純度ガスを露点計に通気してガスの露点温度を検出し、この露点温度に基づいて飽和蒸気圧を求め、これによりガス中の水分量を定量するものである。ここで高純度ガス中の水分量は極めて微量であるため、露点計自体や試料ガスのガス容器と露点計とを結ぶ試料ガスの通気路に水分が付着しているとガス中の水分量を正確に定量できない。
【０００３】
このため実際は、例えば図４に示すように、露点計１１と乾燥ガス供給源１２とを結ぶバルブＶａを備えた配管１３の途中にバルブＶｂを介して試料ガス容器１４を接続して測定経路を組み、高純度ガス中の水分量の定量が行われる。具体的には、前記測定経路では常時乾燥ガス供給源１２から乾燥ガスを配管１３、露点計１１に通気させ、配管１３や露点計１１の内部を乾燥させて内部に付着している水分を除去しており、水分量を定量するときにはバルブＶａを閉じ、バルブＶｂを開いて試料ガス容器１４から試料ガスを配管１３を介して露点計１１に通気して、試料ガス中の水分量を検出するようにしている。
【０００４】
ここで検出値の時間変化をプロットすると、図５に示すような定量曲線が得られ、試料ガス中の水分量は時間の経過と共に少なくなってくるが、これは配管１３や露点計１１内に強力に付着している水分の影響であると考えられる。即ち測定開始時には配管１３等に残存している水分量が多いが、この水分は試料ガスの通気により試料ガスと共に流されていくので、測定時間が経過するに連れて配管１３等に付着している水分量が少なくなるためと考えられる。従って測定開始時の水分量は配管１３等に残存する水分も含むものであるため、検出値の曲線が収束したときの値が試料ガスの水分量となる。
【０００５】
【発明が解決しようとする課題】
しかしながら上述のように、配管１３と露点計１１とに乾燥ガスを通気させただけでは、これらの内部に付着している水分の内容易に除去できるものしか除去できず、強力に付着している水分を完全に除去することができない。また配管１３に試料ガス容器１４を接続する際、容器弁の内部には大気が残っており、試料ガスを配管１３に通気する際、この大気が押し出されてしまうので、配管１３に大気中に存在する水分を供給してしまうこととなる。
【０００６】
このため試料ガス中の水分の定量を行なうと、測定開始時には配管１３等に残存している水分や試料ガス容器１４を接続する際に入り込む水分の量が多いため、例えば１０００ｐｐｍ程度とかなり多く、既述の収束値との差が大きくなるため、なかなか収束値に近付かず、収束するまでの測定時間が例えば６時間程度と非常に長くなってしまう。また配管１３等に残存する水分が多く収束値との差が大きいことから微量な水分量を正確に定量することが困難であるという問題もあった。さらに測定の間は試料ガスを通気し続けなければならないが、測定時間が長いことから、測定中に大量のガスが消費されてしまうという問題もあった。
【０００７】
本発明はこのような事情の下になされたものであり、その目的は、高純度ガス供給部と水分検出計との間を結ぶ高純度ガスの通気路内の水分を除去して、測定時間を短縮し、かつ正確に高純度ガス中の微量の水分の定量を行なうことができる高純度ガス中の水分の定量方法及びその装置を提供することにある。
【０００８】
【課題を解決するための手段】
本発明は、高純度ガス供給部と水分検出計とを結び、水分検出計の下流側まで至る通気路を備え、前記高純度ガス供給部からの高純度ガスを通気路を介して水分検出計に通気させ、高純度ガス中の微量の水分を定量する方法において、前記通気路を減圧してこの通気路内の水分を除去する減圧工程と、次いで前記減圧工程を停止し、前記通気路内に高純度ガスを通気して高純度ガス中の水分を水分検出計にて定量する水分定量工程と、を含むことを特徴とする。また本発明では、減圧工程を行う前に、通気路に乾燥ガスを通気する乾燥工程や通気路を加熱する加熱工程を行うようにしてもよく、このようにすればより一層通気路内の水分が除去できる。さらに本発明では、減圧工程時にも通気路を加熱するようにしてもよい。ここで前記水分定量工程は、水分検出計にて定量された水分濃度の経時変化のデータから水分減少係数を求める工程と、前記水分減少係数に基づいて高純度ガス中の水分量を予測する工程とを含むものであってもよい。
【０００９】
さらにまた本発明の高純度ガス中の水分の定量装置は、高純度ガス供給部と水分検出計とを結び、水分検出計の下流側まで至る通気路を備え、前記高純度ガス供給部からの高純度ガスを通気路を介して水分検出計に通気させ、高純度ガス中の微量の水分を定量する装置において、前記通気路に設けられ、この通気路に乾燥ガスを通気するための乾燥ガス供給手段と、前記通気路に接続され、この通気路内を減圧して通気路内の水分を除去する減圧手段と、前記通気路と乾燥ガス供給手段との間、及び通気路と減圧手段との間に夫々介装された第１のバルブ及び第２のバルブと、を備え、前記第１のバルブを開き、第２のバルブを閉じて前記乾燥ガス供給手段から前記通気路に乾燥ガスを通気し、次いで第１のバルブを閉じ、第２のバルブを開いて前記減圧手段により前記通気路内を減圧し、続いて第１のバルブ及び第２のバルブを閉じて、前記通気路内の減圧を停止し、前記通気路に高純度ガスを通気して高純度ガス中の水分を水分検出計にて定量することを特徴とする。さらにまた前記装置は、前記通気路に設けられ、この通気路を加熱するための加熱手段と、前記通気路に接続され、この通気路内を減圧して通気路内の水分を除去する減圧手段と、前記通気路と減圧手段との間に介装されたバルブと、を備え、前記通気路を加熱手段により加熱し、次いでバルブを開き前記減圧手段により前記通気路内を減圧し、続いてバルブを閉じて前記通記路内の減圧を停止し、前記通気路に高純度ガスを通気して高純度ガス中の水分を水分検出計にて定量するものであってもよい。
【００１０】
【発明の実施の形態】
次に本発明の実施の形態について説明する。本発明は通気路内を減圧することが通気路内の水分の除去に有効であることを見出だした結果成されたものであり、本実施の形態では、高純度ガス中の水分の定量を行う水分定量工程を実施する前に、通気路に乾燥ガスを通気して通気路内を乾燥させる乾燥工程、通気路を加熱して通気路内の水分を除去する加熱工程、通気路内を減圧して通気路内の水分を除去する減圧工程を実施して、通気路内の水分を徹底的に除去してから、通気路に測定しようとする高純度ガスを通気してガス中の水分を定量しようとするものである。
【００１１】
先ず本発明方法を実施するための高純度ガス中の水分の定量装置の構成例について図１に示す経路図により説明すると、図中２１は乾燥ガス例えば乾燥空気を経路内に供給するための乾燥ガス供給手段であり、この後段側には、配管Ｔ１を介してバルブＶ１、Ｖ２、水分検出計例えば露点計３、バルブＶ３、流量計２３、スクラバ２４がこの順番で配設されている。
【００１２】
配管Ｔ１のバルブＶ２の上流側からは、バルブＶ４、Ｖ５を備え、減圧手段をなす減圧ポンプ４に接続された配管Ｔ２が分岐しており、この配管Ｔ２のバルブＶ４の下流側からはバルブＶ９を備え、塩化水素吸収管６に接続された配管Ｔ２１が分岐している。また配管Ｔ１のバルブＶ１とバルブＶ２の間からはバルブＶ６を備えた配管Ｔ３が分岐しており、以上により測定系が構成されている。そして高純度ガス中の水分を定量する際は、この配管Ｔ３に高純度ガス供給部をなす例えば塩化水素ガスのガス容器５が接続される。ここでＶ７は流量調整弁であり、Ｖ８はガス容器５の容器弁である。このような配管やバルブの周囲には例えば図示しないリボンヒ−タからなる加熱手段が配設されている。
【００１３】
この経路図では、ガス容器５の容器弁Ｖ８の下流側から配管Ｔ３、Ｔ１を介して露点計３、バルブＶ３の上流側へ至るまでの図中太線で示す経路が高純度ガスの通気路Ｓを構成しており、バルブＶ１が第１のバルブ、バルブＶ４、Ｖ５が第２のバルブを夫々構成している。
【００１４】
次に高純度ガス中の水分の定量方法について説明する。前記測定系では、常時バルブＶ１、Ｖ２、Ｖ３を開いて、配管Ｔ１に乾燥ガス供給手段２１から乾燥ガス例えば乾燥空気を大気圧で通気している。乾燥ガスとしては窒素ガス等の不活性ガスを用いてもよい。そして高純度ガス中の水分を定量しようとする時には、先ず配管Ｔ３に予め流量調整弁Ｖ７を取り付けた測定しようとする高純度ガスのガス容器５を接続する。
【００１５】
次いで塩化水素ガスの通気路Ｓを減圧する。即ちバルブＶ３を閉じてからバルブＶ１を閉じ、バルブＶ６と流量調整弁Ｖ７とを開いた後、バルブＶ５を開いて減圧ポンプ４により配管Ｔ２のバルブＶ４までの経路を減圧し、次いでバルブＶ４を開いて、容器弁Ｖ８の下流側からバルブＶ３の上流側へ至る通気路Ｓを減圧する。ここでバルブを閉じる際は、露点計３に急激な圧力差を与えないように、最も下流側のバルブＶ３から閉じていくことが望ましい。
【００１６】
続いて乾燥工程と加熱工程とを実施する。即ちバルブＶ４を閉じ、バルブＶ１、Ｖ３を徐々に開き、例えばリボンヒ−タにより配管やバルブを加熱しながら乾燥空気を配管Ｔ１に導入する。このようにすると、通気路Ｓは外側から加熱されると共に、バルブＶ２、Ｖ３、Ｖ６、流量調整弁Ｖ７は開いているので、乾燥空気が容器弁Ｖ８の下流側から通気路Ｓを通り、露点計３、流量計２３を介してスクラバ２４へ通気していく。このため通気路Ｓの内部は、リボンヒ−タによる加熱と乾燥空気の通気により、乾燥されると共に加熱され、この通気路中の配管やバルブ等の内部に付着する水分が除去される。この実施の形態では乾燥工程と加熱工程とが同時に実施される。
【００１７】
次いで減圧工程を実施する。即ちバルブＶ３、Ｖ１を閉じ、バルブＶ４を開いて減圧ポンプ４により配管Ｔ２を介して減圧する。このようにすると、容器弁Ｖ８の下流側からバルブＶ３の上流側へ至る通気路Ｓが例えば１Ｔｏｒｒ程度まで減圧される。この減圧により通気路Ｓ内に付着する水分が吸引されて除去される。この減圧工程においては、リボンヒータにより通気路Ｓ内を加熱しておき、加熱工程も併せて行う。ここでバルブを閉じる際は、上述のように最も下流側のバルブＶ３から閉じていくことが望ましい。
【００１８】
この後通気路Ｓに測定対象である塩化水素ガスを通気させ、塩化水素ガス自身による通気路Ｓ内の水分の除去を行う。具体的には先ず通気路Ｓ内に乾燥空気を導入し、次いで通気路Ｓ内に塩化水素ガスを導入して乾燥空気を塩化水素ガスで置換した後、再び通気路Ｓ内を乾燥空気で置換する。即ちバルブＶ４、Ｖ５、流量調整弁Ｖ７を閉じて、バルブＶ３、Ｖ１を開き通気路Ｓの流量調整弁Ｖ７の下流側に乾燥空気を導入し、配管Ｔ１を介して乾燥空気をスクラバ２４へ通気させた後、容器弁Ｖ８を開き、流量調整弁Ｖ７を徐々に開いて、通気路Ｓ内に塩化水素ガスを導入する。この際流量調整弁Ｖ７を開くにつれてバルブＶ１を徐々に閉じていき、塩化水素ガスが通気路Ｓ内に導入されていることを確認してから乾燥空気の導入を遮断するようにして、露点計３へ急激な圧力差を与えないように、徐々に通気路Ｓ内を塩化水素ガスで置換することが望ましい。このようにして塩化水素ガスをスクラバ２４へ通気させる。
【００１９】
このようにして通気路Ｓを塩化水素ガスで置換した後、再び乾燥空気で置換する。即ち容器弁Ｖ８を閉じ、次いでバルブＶ１を開いて乾燥空気を配管Ｔ１に導入して、スクラバ２４へ通気させた後、バルブＶ３を閉じ、バルブＶ４、Ｖ９を開いて配管Ｔ２、Ｔ２１内に残存する塩化水素ガスを塩化水素吸収管４１に吸収させて除去し、バルブＶ９を閉じる。続いて通気路Ｓ内を減圧して通気路Ｓ内を乾燥させる。即ちバルブＶ１を閉じ、バルブＶ５を開いて減圧ポンプ３によりＴ２１、Ｔ２を介して通気路Ｓ内を例えば１Ｔｏｒｒ程度まで減圧する。このように水分定量前に一旦通気路Ｓ内に塩化水素ガスを通気させると、塩化水素ガスの吸湿性により、通気路Ｓ内に上述の乾燥・加熱・減圧工程を経てもなおかつ強固に付着している水分が塩化水素ガスに吸湿されて除去される。
【００２０】
以上のように乾燥・加熱工程、減圧工程、塩化水素ガス導入工程を実施して、通気路Ｓ内の水分を除去した後、水分定量工程を実施する。即ち上述の方法により一旦通気路Ｓ内に乾燥空気を導入した後、通気路Ｓに塩化水素ガスを導入して通気路Ｓ内を塩化水素ガスで置換する。そして塩化水素ガスを通気路Ｓにより露点計３を介してスクラバ２４へ通気させ、露点計３により塩化水素ガス中の水分を定量する。この定量は、既述のように、塩化水素ガス中の水分の検出値の時間変化をプロットして、例えば図２に示す水分量の定量曲線Ｌ１を作成し、この定量曲線Ｌ１が収束したときの値がガス中の水分量となる。
【００２１】
このような高純度ガス中の水分の定量方法によれば、通気路内の水分の除去を行なう際、通気路を減圧する工程を含めているので、従来の乾燥ガスの通気のみの場合に比べて、通気路内部に付着する水分をより一層除去することができる。即ち通気路に乾燥ガスを通気させた場合には、通気路内の水分は乾燥ガスと接触してガス中に吸収され、乾燥ガスの通気によりこのガスに持ち運ばれて除去される。このため通気路内の比較的に除去しやすい状態の水分のみしか除去できず、通気路の内表面に強力に結合している水分は除去できないが、通気路を減圧した場合には、通気路内に付着している水分が減圧ポンプによる吸引により、通気路の内表面から引き剥がされて除去されるため、通気路の内表面と強力に結合している水分も除去できるからである。
【００２２】
また本実施の形態では、乾燥工程、加熱工程、減圧工程、塩化水素ガス導入工程の４段階の水分除去工程を実施しているので、水分定量工程を実施する前に、通気路内の水分を徹底的に除去することができる。即ち乾燥工程における乾燥ガスによる水分の吸収による除去、加熱工程における水分の蒸発による除去、減圧工程における水分の吸引による除去、塩化水素ガス導入工程における塩化水素ガスへの吸収による除去という、方法の異なる４つの工程により通気路内の水分の除去を行っているので、夫々の工程を行うに連れて通気路の内表面も徐々に変化し、始めは通気路の内表面に強力に付着している水分が徐々に除去しやすい状態になって、確実に除去される。
【００２３】
さらに本実施の形態では、測定系にガス容器５の容器弁Ｖ８を接続して、減圧工程を実施しているので、従来の乾燥ガスの通気では除去が困難であった容器弁Ｖ８のガス流出口の内部に付着する水分を吸引により確実に除去することができ、減圧工程に続いて塩化水素ガス導入工程を実施すればより一層水分を除去することができる。さらにまた露点計３などの外側からの加熱が困難な場所であっても、減圧により水分を除去することができる。
【００２４】
このように本発明では、水分定量工程を実施する前に、通気路内の水分を徹底的に除去し、通気路内の水分量を極めて微量にしているため、高純度ガス中の水分の定量を開始した時の開始当初つまり定量曲線の始めの水分量が少なくなる。従って定量曲線の開始時の水分量と収束時の水分量との差が小さくなるため、収束するまでの時間つまり測定時間が短くなり、この結果高純度ガス中の水分の定量に要する時間を図２に示すように例えば１２５分程度と従来の定量時間（６時間）に比べて大幅に短縮することができる。また高純度ガス中の水分量以外の水分量が極めて微量であることから、誤差が生じにくく、高純度ガス中の水分量の定量を正確に行なうことができる。
【００２５】
なお本実施の形態では、加熱工程は予め乾燥空気を加熱してから、通気路Ｓに通気させることにより行なってもよいし、加熱手段としてはリボンヒ−タの代わりにヒ−トガン等を用いてもよい。また乾燥・加熱工程と減圧工程とを繰り返して行うようにしてもよい。このように繰り返して行うと、前記通気路内の表面が変化し、この表面に強固に付着している水分が除去しやすい状態になるので、より一層通気路Ｓ内の水分が除去される。さらに塩化水素ガス導入工程を数回行うようにしてもよく、これらの工程を繰り返し行うことにより、さらに一層通気路内の水分が除去される。なお塩化水素吸収管６の代わりにスクラバを用いてもよい。また前記高純度ガス供給部は高純度ガスのガス配管であってもよい。
【００２６】
続いて、測定系における水分濃度の経時変化に対して理論解析を十分行うことにより理論式が導かれ、それによって短時間で高純度ガス中の水分量を定量する方法と高純度ガス中の平均水分濃度の測定方法について説明する。これらの方法は、上述の方法により測定された塩化水素ガス中の水分の検出値について、Ｘ軸に測定時間、Ｙ軸に水分量の対数値をプロットすると、良好な直線性を示すことに着目してなされたものである。
【００２７】
先ず高純度ガス中の水分量の予想方法について説明する。図２に示す水分量の測定結果をもとに、Ｘ軸に測定時間、Ｙ軸に水分濃度の対数値をプロットすると、図３に示す水分の定量線Ｌ２が得られる。この直線の式は、
ｌｎＣ＝Ａ_０＋Ａ_１ｔ …（１）
となる。Ｃは水分濃度、ｔは時間である。またＡ_１は水分減少係数であって、直線の傾きから求めることができる。
【００２８】
ここで任意の時間ｔ_１における水分濃度の測定値をＣ_１とすると、式（１）は、
ｌｎＣ_１＝Ａ_０＋Ａ_１ｔ_１ …（２）
となり、この式（２）を、Ａ_０＝ｌｎＣ_１−Ａ_１ｔ_１と変形して、式（１）に代入すると、
ｌｎＣ＝ｌｎＣ_１−Ａ_１ｔ_１＋Ａ_１ｔ …（３）
となり、この式（３）から図２に示す水分の定量曲線Ｌ１の式（５）が次のように求められる。
ｌｎＣ／Ｃ_１＝Ａ_１（ｔ−ｔ_１） …（４）
Ｃ＝Ｃ_１ｅｘｐ｛Ａ_１（ｔ−ｔ_１）｝ …（５）
従って、任意の時間ｔ_１，ｔ_２におけるガス中の水分量を測定し、この測定値に基づいて、水分減少係数Ａ_１を求めれば、式（５）により、水分の定量曲線Ｌ１を得ることができて、収束値の予想が可能となる。これにより、任意の時間ｔ_１，ｔ_２の設定次第でガス中の水分量の測定時間が大幅に短縮する。また任意の時間ｔ_１，ｔ_２におけるガス中の水分量を測定すればよいので、測定に要する労力も大幅に減少する。
【００２９】
次に高純度ガス中の平均水分濃度の測定方法について説明する。ここで平均水分濃度とは、高純度ガスのガス容器から得られる放出ガス中の平均水分濃度をいい、高純度ガス中の水分量のみならず、ガスが通気する際に、ガスによってもたらされる通気路内の水分量を含めた水分量の総量の平均値である。この平均水分濃度は、測定系の通気路内に付着する水分量と高純度ガス中の水分量との和を高純度ガスの通流量で割ったものと定義される。
【００３０】
従って、平均水分濃度Ｃａを求める式（式（６））は、図２に示す水分の定量曲線Ｌ１の式（５）を積分してある時間内の水分量を求め、この水分量をその時間内に通流したガスの総量で割ることにより得られる。
【００３１】
【数１】

ｖは高純度ガスの流速、ｔは任意のガスの放出時間である。
【００３２】
このため、ガス流速一定の下で、ある任意の時間ｔ_１，ｔ_２の水分量を測定して、水分減少係数Ａ_１を求めれば、式（６）により、平均水分濃度Ｃａを求めることができる。これによりガスの放出時間を任意に設定して、この時間内のガスの平均水分濃度を測定することができ、しかも時間ｔ_１，ｔ_２の設定次第で平均水分濃度を短時間で測定することができる。
【００３３】
実際に本発明者らが、上述の方法によって、高純度ガス中の水分量を予測定量を複数回行なったところ、予測して求めた定量曲線Ｌ１は実際に測定した求めた定量曲線Ｌ１とよく一致することが確認され、この予測定量方法により高い精度で水分量を定量することができることが確認された。また平均水分濃度の測定を行なった結果も良好であった。このように予測による水分定量の測定結果の信頼性が高いのは、水分定量工程を行なう前に、徹底的に通気路内の水分除去を行なっているため、水分定量工程時の測定系内の状態をほぼ同じ状態にすることができるためと推察される。また上述の高純度ガス中の水分量の時間変化は、測定時間の代わりにガスの重量やガスの体積を測定して求めるようにしてもよい。
【００３４】
以上において本発明は、塩化水素ガスに限らず例えば塩素ガス等のガス中の水分の定量に適用でき、特に吸湿性の高いガス中の水分の定量に適している。また本発明では、水分定量工程を実施する前に必ずしも乾燥工程、加熱工程、減圧工程、塩化水素ガス導入工程を実施する必要はないし、塩化水素ガス導入工程は必ずしも実施する必要はなく、高純度ガス中の水分量に応じて通気路内の水分の除去を行なうようにすればよい。即ち減圧工程のみを行なうようにしてもよいし、乾燥工程を行ない次いで減圧工程を行なうようにしてもよい。また減圧工程時には、必ずしも加熱工程を実施しなくてもよい。
【００３５】
【実施例】
実施の形態の高純度ガス中の水分の定量装置を用いて、乾燥・加熱工程と減圧工程を３回ずつ繰り返して行ない、塩化水素ガス導入工程を３回行なって通気路内の水分を除去した後、塩化水素ガス中の水分定量工程を実施し、図２に示す定量曲線Ｌ１を得た。水分定量工程の開始時の水分量は約５０ｐｐｍであり、従来の乾燥ガスの通気により通気路内の水分を除去する場合には約１０００ｐｐｍであるため、開始時の水分量が大幅に少なくなった。また定量曲線Ｌ１が収束するまで時間は１２５分であり、従来の測定時間６時間に比べて大幅に短縮された。このようにして定量された塩化水素ガス中の水分量は０．８ｐｐｍであった。
【００３６】
また上記定量曲線Ｌ１の結果をもとに、Ｘ軸に測定時間、Ｙ軸に水分濃度を対数値を採って定量線Ｌ２（図３参照）を作成したところ、良好な直線性を示すことが確認された。そこでこの定量線Ｌ２の傾きから水分減少係数Ａ_１を求め、任意のガスの放出時間を３７７時間として、測定開始後０．５時間の時の水分濃度を測定し、式（６）により_高純度ガス中の水分の平均水分濃度の測定を行なった。ガスの流速は３７．３２リットル／時間に設定した。定量線Ｌ２から求めた水分減少係数Ａ_１は２．２０３、測定開始後０．５時間の時の水分濃度は１７ｐｐｍであり、これらを式（６）に代入して得られた、ガスの放出時間３７７時間中の平均水分濃度Ｃａは０．８４２７ｐｐｂであった。
【００３７】
【発明の効果】
本発明によれば、高純度ガス中の水分を定量を短時間でかつ正確に行なうことができる。
【図面の簡単な説明】
【図１】本発明の実施の形態の高純度ガス中の水分の定量装置の一例を示す経路図である。
【図２】本発明方法により塩化水素ガス中の水分を定量した場合の定量曲線Ｌ１である。
【図３】本発明方法により塩化水素ガス中の水分を定量した場合の定量線Ｌ２である。
【図４】従来の高純度ガス中の水分の定量の測定経路図である。
【図５】高純度ガス中の水分の定量曲線である。
【符号の説明】
２１乾燥ガス供給手段
２３流量計
３露点計
４減圧ポンプ
５ガス容器
６塩化水素吸収管
Ｖ８容器弁
Ｓ通気路[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method and an apparatus for determining water in a high-purity gas.
[0002]
[Prior art]
For example, the dew point method is known as one of the methods for quantifying water in a high-purity gas such as anhydrous hydrogen chloride gas. In this method, a high-purity gas is passed through a dew point meter to detect the dew point temperature of the gas, and a saturated vapor pressure is determined based on the dew point temperature, thereby quantifying the water content in the gas. Here, the moisture content in the high-purity gas is extremely small, so if moisture is attached to the dew point meter itself or the gas passage of the sample gas connecting the gas container for the sample gas and the dew point meter, the moisture content in the gas is reduced. Cannot be quantified accurately.
[0003]
Therefore, in practice, for example, as shown in FIG. 4, a sample gas container 14 is connected via a valve Vb in the middle of a pipe 13 provided with a valve Va connecting the dew point meter 11 and the dry gas supply source 12, and the measurement path is changed. The amount of water in the high-purity gas is determined. Specifically, in the measurement path, a dry gas is constantly passed from the dry gas supply source 12 to the pipe 13 and the dew point meter 11 to dry the inside of the pipe 13 and the dew point meter 11 to remove moisture adhering to the inside. When the amount of moisture is determined, the valve Va is closed, the valve Vb is opened, and the sample gas is passed from the sample gas container 14 to the dew point meter 11 via the pipe 13 to detect the amount of moisture in the sample gas. Like that.
[0004]
Here, when the time change of the detected value is plotted, a quantitative curve as shown in FIG. 5 is obtained, and the amount of water in the sample gas decreases with time. This is considered to be the effect of strongly attached moisture. That is, at the start of the measurement, the amount of water remaining in the pipe 13 and the like is large, but this water flows along with the sample gas by aeration of the sample gas, so that the water adheres to the pipe 13 and the like as the measurement time elapses. This is probably because the amount of water in the container decreases. Therefore, the amount of water at the start of measurement includes the amount of water remaining in the pipe 13 and the like, and the value when the curve of the detected value converges is the amount of water in the sample gas.
[0005]
[Problems to be solved by the invention]
However, as described above, by merely passing the dry gas through the pipe 13 and the dew point meter 11, only those which can easily be removed from the water adhering to the inside can be removed, and the water adheres strongly. Water cannot be completely removed. When the sample gas container 14 is connected to the pipe 13, air remains inside the container valve, and when the sample gas is passed through the pipe 13, this air is pushed out. It will supply existing moisture.
[0006]
Therefore, when the amount of water in the sample gas is determined, the amount of water remaining in the pipe 13 and the like and the amount of water entering when the sample gas container 14 is connected at the start of the measurement are large. Since the difference from the convergence value described above becomes large, the convergence value does not easily approach, and the measurement time until convergence becomes extremely long, for example, about 6 hours. In addition, there is also a problem that it is difficult to accurately determine a trace amount of water because the amount of water remaining in the pipe 13 and the like is large and the difference from the convergence value is large. Further, the sample gas must be kept ventilated during the measurement, but there is a problem that a large amount of gas is consumed during the measurement due to the long measurement time.
[0007]
The present invention has been made under such circumstances, and an object of the present invention is to remove moisture in a high-purity gas ventilation path connecting a high-purity gas supply unit and a moisture detector to measure a measurement time. It is an object of the present invention to provide a method and an apparatus for determining the amount of water in a high-purity gas, which can reduce the amount of water and accurately determine a trace amount of water in the high-purity gas.
[0008]
[Means for Solving the Problems]
The present invention provides a high-purity gas supply unit and a moisture detector, a ventilation path extending to the downstream side of the moisture detector, and a high-purity gas from the high-purity gas supply unit through the ventilation path. In the method for quantifying a trace amount of water in a high-purity gas, a pressure reducing step of removing the water in the ventilation path by reducing the pressure in the ventilation path, and then stopping the pressure reducing step, And a moisture quantifying step of quantifying the moisture in the high-purity gas with a moisture detector by passing a high-purity gas through the water. Further, in the present invention, before performing the depressurizing step, a drying step of passing a dry gas through the ventilation path or a heating step of heating the ventilation path may be performed, so that the moisture in the ventilation path can be further improved. Can be removed. Furthermore, in the present invention, the ventilation path may be heated even during the pressure reduction step. Here, the moisture determination step is a step of obtaining a moisture reduction coefficient from data of a temporal change of the moisture concentration determined by the moisture detector, and a step of predicting the moisture amount in the high-purity gas based on the moisture reduction coefficient. May be included.
[0009]
Furthermore, the apparatus for quantifying moisture in a high-purity gas of the present invention connects a high-purity gas supply unit and a moisture detector, has a ventilation path extending to the downstream side of the moisture detector, In a device for allowing a high-purity gas to pass through a moisture detector through a ventilation path and quantifying a trace amount of moisture in the high-purity gas, the drying gas is provided in the ventilation path, and the drying gas for passing the drying gas through the ventilation path. Supply means, connected to the ventilation path, decompression means for reducing the pressure in the ventilation path to remove moisture in the ventilation path, between the ventilation path and the dry gas supply means, and between the ventilation path and the decompression means, A first valve and a second valve interposed therebetween, wherein the first valve is opened, the second valve is closed, and the drying gas is supplied from the drying gas supply means to the ventilation path. Vent, then close the first valve and open the second valve Then, the inside of the ventilation path is depressurized by the decompression means, and then the first valve and the second valve are closed to stop the decompression in the ventilation path. It is characterized in that the moisture in the purity gas is quantified by a moisture detector. Furthermore, the apparatus is provided in the ventilation path, and heating means for heating the ventilation path, and decompression means connected to the ventilation path, for reducing the pressure in the ventilation path to remove moisture in the ventilation path. And a valve interposed between the ventilation path and the decompression means, wherein the ventilation path is heated by a heating means, and then the valve is opened to reduce the pressure in the ventilation path by the decompression means. The valve may be closed to stop the depressurization in the communication path, and high-purity gas may be passed through the ventilation path to determine the moisture in the high-purity gas with a moisture detector.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, an embodiment of the present invention will be described. The present invention has been made as a result of finding that reducing the pressure in the air passage is effective for removing moisture in the air passage.In the present embodiment, the quantitative determination of the water in the high-purity gas is performed. Before performing the moisture determination step, a drying step of drying the inside of the ventilation path by passing dry gas through the ventilation path, a heating step of heating the ventilation path to remove moisture in the ventilation path, and reducing the pressure in the ventilation path Perform a decompression step to remove moisture in the ventilation path, thoroughly remove the moisture in the ventilation path, and then vent the high-purity gas to be measured through the ventilation path to remove the moisture in the gas. It is to be quantified.
[0011]
First, an example of the configuration of a device for quantifying the moisture in a high-purity gas for carrying out the method of the present invention will be described with reference to the path diagram shown in FIG. 1. On the subsequent side, valves V1 and V2, a moisture detector, for example, a dew point meter 3, a valve V3, a flow meter 23, and a scrubber 24 are arranged in this order via a pipe T1.
[0012]
From the upstream side of the valve V2 of the pipe T1, a pipe T2 provided with valves V4 and V5 and connected to a decompression pump 4 serving as a decompression means branches off, and a valve V9 is provided from a downstream side of the valve V4 of the pipe T2. And a pipe T21 connected to the hydrogen chloride absorption pipe 6 is branched. Further, a pipe T3 provided with a valve V6 branches from between the valve V1 and the valve V2 of the pipe T1, and a measurement system is configured as described above. Then, when quantifying the moisture in the high-purity gas, a gas container 5 of, for example, hydrogen chloride gas, which forms a high-purity gas supply unit, is connected to the pipe T3. Here, V7 is a flow control valve, and V8 is a container valve of the gas container 5. A heating means such as a ribbon heater (not shown) is provided around such pipes and valves.
[0013]
In this path diagram, the path indicated by a thick line in the figure from the downstream side of the container valve V8 of the gas container 5 to the dew point meter 3 and the upstream side of the valve V3 via the pipes T3 and T1 is a high purity gas ventilation path S The valve V1 constitutes a first valve, and the valves V4 and V5 constitute a second valve.
[0014]
Next, a method for quantifying water in a high-purity gas will be described. In the measurement system, the valves V1, V2, and V3 are always opened, and a dry gas such as dry air is passed from the dry gas supply unit 21 to the pipe T1 at atmospheric pressure. An inert gas such as a nitrogen gas may be used as the drying gas. When the amount of moisture in the high-purity gas is to be determined, a gas container 5 for high-purity gas to be measured, to which a flow control valve V7 is attached in advance, is connected to the pipe T3.
[0015]
Next, the pressure of the gas passage S for hydrogen chloride gas is reduced. That is, after the valve V3 is closed, the valve V1 is closed, the valve V6 and the flow regulating valve V7 are opened, the valve V5 is opened, the pressure of the path to the valve V4 of the pipe T2 is reduced by the pressure reducing pump 4, and then the valve V4 is opened. When opened, the pressure in the air passage S from the downstream side of the container valve V8 to the upstream side of the valve V3 is reduced. Here, when closing the valve, it is desirable to close the valve from the most downstream valve V3 so as not to give a sudden pressure difference to the dew point meter 3.
[0016]
Subsequently, a drying step and a heating step are performed. That is, the valve V4 is closed, the valves V1 and V3 are gradually opened, and dry air is introduced into the pipe T1 while heating the pipes and valves by, for example, a ribbon heater. In this case, the ventilation path S is heated from the outside, and the valves V2, V3, V6 and the flow control valve V7 are open, so that the dry air passes through the ventilation path S from the downstream side of the container valve V8 and has a dew point. A total of 3 is ventilated to the scrubber 24 via the flow meter 23. For this reason, the inside of the ventilation path S is dried and heated by the heating by the ribbon heater and the ventilation of the dry air, and the moisture adhering to the inside of the pipes, valves and the like in the ventilation path is removed. In this embodiment, the drying step and the heating step are performed simultaneously.
[0017]
Next, a pressure reduction step is performed. That is, the valves V3 and V1 are closed, the valve V4 is opened, and the pressure is reduced by the pressure reducing pump 4 via the pipe T2. In this way, the pressure of the air passage S from the downstream side of the container valve V8 to the upstream side of the valve V3 is reduced to, for example, about 1 Torr. Due to this reduced pressure, the moisture adhering to the air passage S is sucked and removed. In this pressure reduction step, the inside of the ventilation path S is heated by the ribbon heater, and the heating step is also performed. Here, when closing the valve, it is desirable to close the valve from the most downstream valve V3 as described above.
[0018]
Thereafter, the hydrogen chloride gas to be measured is passed through the ventilation path S, and moisture in the ventilation path S is removed by the hydrogen chloride gas itself. Specifically, first, dry air is introduced into the ventilation path S, then hydrogen chloride gas is introduced into the ventilation path S to replace the dry air with hydrogen chloride gas, and then the inside of the ventilation path S is replaced with dry air again. I do. That is, the valves V4 and V5 and the flow control valve V7 are closed, and the valves V3 and V1 are opened to introduce dry air downstream of the flow control valve V7 in the ventilation path S, and the dry air is passed to the scrubber 24 via the pipe T1. After that, the container valve V8 is opened, and the flow rate adjusting valve V7 is gradually opened, and hydrogen chloride gas is introduced into the ventilation path S. At this time, as the flow control valve V7 is opened, the valve V1 is gradually closed to confirm that the hydrogen chloride gas has been introduced into the ventilation passage S, and then the introduction of the dry air is shut off. It is desirable to gradually replace the inside of the ventilation path S with hydrogen chloride gas so as not to give a sudden pressure difference to the pressure sensor 3. Thus, the hydrogen chloride gas is passed through the scrubber 24.
[0019]
After replacing the air passage S with the hydrogen chloride gas in this manner, the air passage S is again replaced with the dry air. That is, the container valve V8 is closed, then the valve V1 is opened, and dry air is introduced into the pipe T1 and aerated through the scrubber 24. Then, the valve V3 is closed, and the valves V4 and V9 are opened to remain in the pipes T2 and T21. The hydrogen chloride gas to be removed is absorbed by the hydrogen chloride absorption tube 41 and removed, and the valve V9 is closed. Subsequently, the inside of the ventilation path S is depressurized to dry the inside of the ventilation path S. That is, the valve V1 is closed, the valve V5 is opened, and the pressure in the air passage S is reduced by the pressure reducing pump 3 to about 1 Torr through T21 and T2. As described above, once hydrogen chloride gas is passed through the ventilation passage S before the determination of the moisture content, the hydrogen chloride gas is strongly adhered to the ventilation passage S through the above-described drying, heating and depressurizing steps due to the hygroscopicity of the hydrogen chloride gas. Moisture absorbed by the hydrogen chloride gas is removed.
[0020]
As described above, the drying / heating step, the depressurizing step, and the hydrogen chloride gas introducing step are performed to remove the water in the ventilation path S, and then the water quantifying step is performed. That is, after the dry air is once introduced into the ventilation path S by the above-described method, hydrogen chloride gas is introduced into the ventilation path S, and the inside of the ventilation path S is replaced with hydrogen chloride gas. Then, the hydrogen chloride gas is passed through the dew point meter 3 to the scrubber 24 through the ventilation path S, and the moisture in the hydrogen chloride gas is quantified by the dew point meter 3. As described above, the quantification is performed by plotting the time change of the detected value of the water content in the hydrogen chloride gas to form a quantification curve L1 of the water content shown in FIG. 2, for example, when the quantification curve L1 converges. Is the amount of water in the gas.
[0021]
According to such a method for determining the moisture in the high-purity gas, when the moisture in the ventilation path is removed, a step of depressurizing the ventilation path is included. As a result, moisture adhering to the inside of the ventilation path can be further removed. That is, when the drying gas is passed through the ventilation path, the moisture in the ventilation path comes into contact with the drying gas and is absorbed into the gas, and is carried to and removed by the gas by the ventilation of the drying gas. For this reason, only water in a relatively easy-to-remove state in the ventilation path can be removed, and water strongly bonded to the inner surface of the ventilation path cannot be removed. This is because the moisture adhering to the inside is peeled off and removed from the inner surface of the ventilation path by suction by the decompression pump, so that the moisture strongly bonded to the inner surface of the ventilation path can also be removed.
[0022]
Further, in the present embodiment, since the four-stage water removal step of the drying step, the heating step, the decompression step, and the hydrogen chloride gas introduction step is performed, the water in the ventilation path is removed before the water determination step is performed. It can be thoroughly removed. That is, the methods are different: removal by absorption of moisture by a drying gas in a drying step, removal by evaporation of moisture in a heating step, removal by suction of moisture in a decompression step, and removal by absorption into hydrogen chloride gas in a hydrogen chloride gas introduction step. Since the water in the ventilation path is removed by four steps, the inner surface of the ventilation path also gradually changes as each step is performed, and initially adheres strongly to the inner surface of the ventilation path. Moisture gradually becomes easy to remove and is reliably removed.
[0023]
Further, in the present embodiment, since the pressure reducing step is performed by connecting the container valve V8 of the gas container 5 to the measurement system, the gas flow of the container valve V8, which has been difficult to remove by the conventional ventilation of dry gas, is performed. Moisture adhering to the inside of the outlet can be reliably removed by suction, and if a hydrogen chloride gas introduction step is performed subsequent to the decompression step, the water can be further removed. Further, even in a place where heating from the outside such as the dew point meter 3 is difficult, moisture can be removed by decompression.
[0024]
As described above, according to the present invention, before performing the moisture determination step, the moisture in the ventilation path is thoroughly removed, and the moisture content in the ventilation path is made extremely small. At the beginning of the quantification curve, ie, at the beginning of the quantitative curve, is reduced. Therefore, the difference between the amount of water at the start of the quantitative curve and the amount of water at the time of convergence is reduced, and the time required for convergence, that is, the measurement time, is shortened. As shown in FIG. 2, for example, about 125 minutes can be drastically reduced as compared with the conventional quantitative time (6 hours). Further, since the amount of water other than the amount of water in the high-purity gas is extremely small, an error hardly occurs, and the amount of water in the high-purity gas can be accurately determined.
[0025]
In the present embodiment, the heating step may be performed by heating the dry air in advance and then ventilating the air through the ventilation path S, or using a heat gun or the like as the heating means instead of the ribbon heater. Is also good. Further, the drying / heating step and the pressure reducing step may be performed repeatedly. By repeatedly performing in this manner, the surface in the air passage changes, and the water firmly attached to the surface is easily removed, so that the water in the air passage S is further removed. Further, the hydrogen chloride gas introduction step may be performed several times, and by repeating these steps, the moisture in the air passage is further removed. Note that a scrubber may be used instead of the hydrogen chloride absorption tube 6. The high-purity gas supply unit may be a gas pipe for high-purity gas.
[0026]
Subsequently, a theoretical equation is derived by sufficiently performing a theoretical analysis on the change over time of the moisture concentration in the measurement system, whereby a method for quantifying the amount of moisture in the high-purity gas in a short time and an average in the high-purity gas are obtained. A method for measuring the moisture concentration will be described. These methods focus on the fact that when the measured time of water in hydrogen chloride gas measured by the above method is plotted with the measurement time on the X-axis and the logarithmic value of the water content on the Y-axis, good linearity is exhibited. It was done.
[0027]
First, a method of estimating the amount of water in a high-purity gas will be described. When the measurement time is plotted on the X-axis and the logarithmic value of the water concentration is plotted on the Y-axis based on the measurement result of the water content shown in FIG. 2, a quantitative line L2 of water shown in FIG. 3 is obtained. The equation for this line is
lnC = A ₀ + A ₁ t (1)
It becomes. C is the moisture concentration and t is the time. The A ₁ is a moisture reduction factor can be determined from the slope of the straight line.
[0028]
Here, assuming that the measured value of the water concentration at an arbitrary time t ₁ is C ₁ , the equation (1) becomes:
lnC ₁ = A ₀ + A ₁ t ₁ (2)
When this equation (2) is transformed into A ₀ = InC ₁ −A ₁ t ₁ and substituted into the equation (1),
_{_{_{_{lnC = lnC 1 -A 1 t 1}}}} + A 1 t ... (3)
From the equation (3), the equation (5) of the moisture quantification curve L1 shown in FIG. 2 is obtained as follows.
lnC / C ₁ = A ₁ (t−t ₁ ) (4)
C = C ₁ exp {A ₁ (t−t ₁ )} (5)
Therefore, by measuring the amount of water in the gas at arbitrary times t ₁ and t ₂ and obtaining the water reduction coefficient A ₁ based on the measured values, a quantitative curve L 1 of water can be obtained by equation (5). And the convergence value can be predicted. Thereby, the measurement time of the amount of water in the gas is greatly reduced depending on the settings of the arbitrary times t ₁ and t ₂ . Further, since it is sufficient to measure the amount of water in the gas at arbitrary times t ₁ and t _2, the labor required for the measurement is greatly reduced.
[0029]
Next, a method for measuring the average moisture concentration in the high-purity gas will be described. Here, the average moisture concentration means the average moisture concentration in the released gas obtained from the gas container of the high-purity gas, and not only the amount of moisture in the high-purity gas but also the ventilation caused by the gas when the gas is ventilated. It is the average value of the total amount of water including the amount of water in the road. This average moisture concentration is defined as a value obtained by dividing the sum of the amount of moisture adhering in the ventilation path of the measurement system and the amount of moisture in the high-purity gas by the flow rate of the high-purity gas.
[0030]
Accordingly, the equation (Equation (6)) for calculating the average moisture concentration Ca is obtained by integrating the equation (5) of the moisture quantitative curve L1 shown in FIG. It is obtained by dividing by the total amount of gas flowing through.
[0031]
(Equation 1)

v is the flow rate of the high-purity gas, and t is the release time of any gas.
[0032]
For this reason, when the water content at certain arbitrary times t ₁ and t ₂ is measured under a constant gas flow rate and the water reduction coefficient A ₁ is obtained, the average water concentration Ca can be obtained by the equation (6). it can. Thus, the gas release time can be set arbitrarily, and the average moisture concentration of the gas within this time can be measured. In addition, the average moisture concentration can be measured in a short time depending on the settings of the times t ₁ and t _2. Can be.
[0033]
When the present inventors actually performed the prediction and quantification of the amount of water in the high-purity gas a plurality of times by the above-described method, the quantification curve L1 predicted and obtained was quite similar to the quantification curve L1 actually obtained. The agreement was confirmed, and it was confirmed that the water content could be quantified with high accuracy by this predictive quantification method. The result of measurement of the average moisture concentration was also good. The high reliability of the predicted moisture quantification measurement results is because the water in the ventilation path is thoroughly removed before performing the moisture quantification process, It is presumed that the states can be made almost the same. Further, the above-mentioned temporal change in the amount of water in the high-purity gas may be obtained by measuring the weight of the gas or the volume of the gas instead of the measurement time.
[0034]
As described above, the present invention can be applied not only to hydrogen chloride gas but also to determination of moisture in a gas such as chlorine gas, and is particularly suitable for determination of moisture in a highly hygroscopic gas. In the present invention, the drying step, the heating step, the decompression step, and the hydrogen chloride gas introduction step are not necessarily performed before the moisture determination step is performed, and the hydrogen chloride gas introduction step is not necessarily performed. The moisture in the ventilation path may be removed according to the moisture content in the gas. That is, only the pressure reduction step may be performed, or the drying step may be performed, and then the pressure reduction step may be performed. In addition, at the time of the pressure reduction step, the heating step does not necessarily have to be performed.
[0035]
【Example】
The drying / heating step and the depressurizing step were repeated three times each using the apparatus for quantifying the moisture in the high-purity gas of the embodiment, and the hydrogen chloride gas introducing step was performed three times to remove the moisture in the ventilation passage. Thereafter, a step of determining the water content in the hydrogen chloride gas was performed, and a quantitative curve L1 shown in FIG. 2 was obtained. The amount of water at the start of the moisture determination step was about 50 ppm, and when the moisture in the ventilation path was removed by aeration of the conventional dry gas, it was about 1000 ppm. . The time required for the quantitative curve L1 to converge is 125 minutes, which is significantly shorter than the conventional measurement time of 6 hours. The water content in the hydrogen chloride gas thus determined was 0.8 ppm.
[0036]
Further, based on the results of the quantitative curve L1, a quantitative line L2 (see FIG. 3) was prepared by taking the measurement time on the X-axis and the logarithmic value of the water concentration on the Y-axis. confirmed. So determined moisture reduction factor A ₁ from the slope of the quantitative line L2, the release time of any gas as 377 hours, measuring the water concentration at the time of 0.5 hours after the start of measurement, _{a high} purity by the formula (6) The average moisture concentration of the moisture in the gas was measured. The gas flow rate was set at 37.32 liters / hour. Moisture reduction factor _{A 1} obtained from quantitative line L2 2.203, water concentration at 0.5 hours after the start of measurement is 17 ppm, these were obtained by substituting the equation (6), the release of gas The average water concentration Ca during the 377 hours was 0.8427 ppb.
[0037]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the quantity of water in a high-purity gas can be determined accurately in a short time.
[Brief description of the drawings]
FIG. 1 is a path diagram showing an example of an apparatus for quantifying moisture in a high-purity gas according to an embodiment of the present invention.
FIG. 2 is a quantification curve L1 in the case where water in hydrogen chloride gas is quantified by the method of the present invention.
FIG. 3 is a quantification line L2 when water in hydrogen chloride gas is quantified by the method of the present invention.
FIG. 4 is a conventional measurement path diagram for quantitative determination of water in a high-purity gas.
FIG. 5 is a quantitative curve of water in a high-purity gas.
[Explanation of symbols]
21 Dry gas supply means 23 Flow meter 3 Dew point meter 4 Decompression pump 5 Gas container 6 Hydrogen chloride absorption tube V8 Container valve S Vent path

Claims

A high-purity gas supply unit and a moisture detector are connected, and a ventilation path is provided to the downstream side of the moisture detector, and the high-purity gas from the high-purity gas supply unit is passed through the moisture detector through the ventilation path, In the method of quantifying a trace amount of water in high-purity gas,
A decompression step of decompressing the air passage to remove water in the air passage;
Next, the pressure reduction step is stopped , and a high-purity gas is passed through the ventilation path to determine a water content of the high-purity gas with a water detector.
A method for quantifying water in a high-purity gas, comprising:

A high-purity gas supply unit and a moisture detector are connected, and a ventilation path is provided to the downstream side of the moisture detector, and the high-purity gas from the high-purity gas supply unit is passed through the moisture detector through the ventilation path, In the method of quantifying a trace amount of water in high-purity gas,
A drying step of passing a drying gas through the ventilation path,
Next, the drying step is stopped, and a pressure reducing step of reducing the pressure in the ventilation path to remove water in the ventilation path;
Subsequently, the pressure reducing step is stopped , and a high-purity gas is passed through the ventilation path to determine a water content in the high-purity gas with a water detector.
A method for quantifying water in a high-purity gas, comprising:

A high-purity gas supply unit and a moisture detector are connected, and a ventilation path is provided to the downstream side of the moisture detector, and the high-purity gas from the high-purity gas supply unit is passed through the moisture detector through the ventilation path, In the method of quantifying a trace amount of water in high-purity gas,
A heating step of heating the ventilation path,
Next, the pressure in the ventilation path is reduced, and a pressure reducing step of removing water in the ventilation path,
Subsequently, the pressure reducing step is stopped , and a high-purity gas is passed through the ventilation path to determine a water content in the high-purity gas with a water detector.
A method for quantifying water in a high-purity gas, comprising:

4. The method according to claim 1, wherein the pressure reducing step is a step of reducing the pressure while heating the ventilation path.

The moisture determination step is a step of obtaining a moisture reduction coefficient from data of a temporal change of the moisture concentration determined by the moisture detector,
Predicting the amount of moisture in the high-purity gas based on the moisture reduction coefficient,
The method for quantifying water in a high-purity gas according to claim 1, wherein the method further comprises:

A high-purity gas supply unit and a moisture detector are connected, and a ventilation path is provided to the downstream side of the moisture detector, and the high-purity gas from the high-purity gas supply unit is passed through the moisture detector through the ventilation path, In a device that determines a trace amount of water in high-purity gas,
Dry gas supply means provided in the ventilation path, for aerating the drying gas into the ventilation path,
A pressure reducing means connected to the ventilation path, for removing water in the ventilation path by reducing the pressure in the ventilation path;
A first valve and a second valve interposed between the ventilation path and the drying gas supply unit and between the ventilation path and the decompression unit, respectively;
The first valve is opened, the second valve is closed and the drying gas is passed from the drying gas supply means to the ventilation path, and then the first valve is closed, and the second valve is opened to open the second valve. The inside of the ventilation path is depressurized by the decompression means, then the first valve and the second valve are closed to stop the decompression in the ventilation path, and the high-purity gas is passed through the ventilation path. An apparatus for quantifying moisture in high-purity gas, characterized in that moisture in the gas is determined by a moisture detector.

A high-purity gas supply unit and a moisture detector are connected, and a ventilation path is provided to the downstream side of the moisture detector, and the high-purity gas from the high-purity gas supply unit is passed through the moisture detector through the ventilation path, In a device that determines a trace amount of water in high-purity gas,
Heating means provided in the ventilation path, for heating the ventilation path,
A pressure reducing means connected to the ventilation path, for removing water in the ventilation path by reducing the pressure in the ventilation path;
A valve interposed between the ventilation path and the decompression means,
The ventilation path is heated by heating means, then the valve is opened, the pressure in the ventilation path is reduced by the pressure reducing means, and then the valve is closed to stop reducing the pressure in the communication path. An apparatus for quantifying moisture in a high-purity gas, wherein high-purity gas is ventilated and moisture in the high-purity gas is quantified by a moisture detector.