JP4009952B2 - Magnetic oxygen measuring method and magnetic oxygen meter - Google Patents

Magnetic oxygen measuring method and magnetic oxygen meter Download PDF

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JP4009952B2
JP4009952B2 JP2003123289A JP2003123289A JP4009952B2 JP 4009952 B2 JP4009952 B2 JP 4009952B2 JP 2003123289 A JP2003123289 A JP 2003123289A JP 2003123289 A JP2003123289 A JP 2003123289A JP 4009952 B2 JP4009952 B2 JP 4009952B2
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auxiliary gas
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gas
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JP2004325368A (en
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秀章 山岸
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Yokogawa Electric Corp
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Description

【０００１】
【発明の属する技術分野】
本発明は、磁気式酸素測定方法及び磁気式酸素計に関するものであり、特に、補助ガス流路に改良を加えてリングセルの傾斜に依存しないで酸素ガスの量を検出できるようにした磁気式酸素測定方法及び磁気式酸素計に関する。
【０００２】
【従来の技術】
従来技術における磁気式酸素計は、図３及び図４に示すように、被測定ガス（サンプルガス）を流す流路を備えたリングセル１１１と、このリングセル１１１内に設置した熱型流量センサ（サーミスタ）からの信号で被測定ガスに含まれている酸素ガスの流量を検出する検出回路１２０とからなる。
【０００３】
リングセル１１１は、円環形状に形成されたサンプル流路１１２に連通して設けた測定ガス導入口１１３と、この測定ガス導入口１１３の反対側に設けた測定ガス導出口１１４と、円環形状のサンプル流路１１２の中心位置を通り、対向する側のそれぞれに連通させて形成した第１及び第２の補助ガス流路１１５ａ、１１５ｂと、第１及び第２の補助ガス流路１１５ａ、１１５ｂに連通してあるサンプル流路１１２の片側である測定側サンプル流路１１２ａに磁界を形成するヨーク１１６（図４参照）と、第１及び第２の補助ガス流路１１５ａ、１１５ｂの中心位置に連通され補助ガスを流入する補助ガス導入口１１７と、第１及び第２の補助ガス流路１１５ａ、１１５ｂ内部に補助ガス導入口１１７を中心として同距離の位置に備えた第１及び第２のサーミスタ１１８ａ、１１８ｂとを備えた構成になっている。この第１及び第２のサーミスタ１１８ａ、１１８ｂは、検出回路１２０に接続されている。
【０００４】
検出回路１２０は、第１のサーミスタ１１８ａに接続してある第１の定抵抗回路１２１ａと、第２のサーミスタ１１８ｂに接続してある第２の定抵抗回路１２１ｂと、これらの第１及び第２の定抵抗回路１２１ａ、１２１ｂからの信号を受信する差動増幅器１２２とからなる。
【０００５】
このような構成のリングセル１１１において、測定ガス導入口１１３から導入された被測定ガスは二方向に分流したのち、測定ガス導出口１１４へ合流するように流れる。
また、補助ガス導入口１１７から導入された補助ガスは二方向に分流したのち、第１及び第２のサーミスタ１１８ａ、１１８ｂをそれぞれ経由し、その後、第１及び第２の補助ガス流路１１５ａ、１１５ｂとの接続部付近でそれぞれ被測定ガスと合流し、被測定ガスと共に測定ガス導出口１１４へ流れる。
【０００６】
このような状況下で、被測定ガス中に酸素分子が含まれていない場合、第１のサーミスタ１１８ａを経由する補助ガスの流量と第２のサーミスタ１１８ｂを経由する補助ガスの流量は同一となる。
【０００７】
このため、第１の定抵抗回路１２１ａに入力される第１のサーミスタ１１８ａの出力と第２の定抵抗回路１２１ｂに入力される第２のサーミスタ１１８ｂの出力も同一となり、第１の定抵抗回路１２１ａの出力信号と第２の定抵抗回路１２１ｂの出力信号も同一となり、これらの出力信号の差を増幅する差動増幅器１２２の出力は零になる。
【０００８】
一方、測定ガス中に酸素分子が含まれている場合、ヨーク１１６による磁界印加領域における磁力作用により測定ガス中の酸素分子が引き付けられて部分流れが生じる。このため、第１のサーミスタ１１８ａを経由する補助ガスの流量と第２のサーミスタ１１８ｂを経由する補助ガスの流量に差が生じるようになり、第１の定抵抗回路１２１ａに入力される第１のサーミスタ１１８ａの出力信号と第２の定抵抗回路１２１ｂに入力される第２のサーミスタ１１８ｂの出力信号が同一でなくなる。
従って、第１の定抵抗回路１２１ａの出力信号と第２の定抵抗回路１２１ｂの出力信号も異なるようになり、第１の定抵抗回路１２１ａの出力信号と第２の定抵抗回路１２１ｂの出力信号の差を増幅する差動増幅器１２２の出力信号が測定ガス中の酸素分子量に対応した値を示すようになる。
【０００９】
さて、図４に示すように、リングセル１１１は、補助ガスを流す第１及び第２の補助ガス流路１１５ａ、１１５ｂが、補助ガス導入口１１７から分流するときに同一量のガスを分流させる必要がある。その分流したガスの量に応じて第１及び第２のサーミスタ１１８ａ、１１８ｂの温度の冷却状態を検出するからである。そのため、補助ガス導入口１１７を中心にして、第１及び第２の補助ガス流路１１５ａ、１１５ｂが平行になるように設置している。
【００１０】
【特許文献１】
特開平５−１７２７８４号公報 （第２〜３頁 第２図）
【００１１】
【発明が解決しようとする課題】
しかしながら、従来技術で説明した磁気式酸素計において、実際に補助ガス流路を平行に設置することは難しく、図５に示すように、磁界を発生させる測定側サンプル流路１１２ａが下に傾斜すると、補助ガスの熱対流は比較側サンプル流路１１２ｂ側に多く流れてしまうことになる。
又、図６に示すように、磁界を発生させる測定側サンプル流路１１２ａが上方向に傾斜すると、補助ガスの熱対流は、測定側サンプル流路１１２ａ側に多く流れてしまう。
【００１２】
このように、わずかなリングセル１１１の傾斜により、大きな誤差（信号オフセット）を生じてしまい、概略として、１度の傾斜で、０−１％０２レンジのほぼフルスケールに相当する信号オフセットを生じる。
これは、現状のリングセル１１１は、リングセル１１１を平面上に構成しているために、測定側サンプル流路１１２ａと比較側サンプル流路１１２ｂへの補助ガスはちょうど正反対方向に流れる構造となっているからである。
このような構造において、第１及び第２の補助ガス流路１１５ａ、１１５ｂ中に挿入されている第１及び第２のサーミスタ（自己加熱サーミスタ）１１８ａ、１１８ｂが発生する熱が、流路の傾斜により、信号への大きなオフセットを加える結果となる。
これは、現行製品が第１及び第２の補助ガス流路１１５ａ、１１５ｂの傾斜Θに対して、信号オフセットがｓｉｎΘに比例して依存する形になっているからである。非常に傾斜に敏感なセンサとなっているため、実際の製品の設置に際して、現場設置してからリングセル１１１の傾斜微調整を行い、水平出しを行う必要がある。
このため、防爆容器の外部から傾斜微調整を行う複雑なリンク機構を搭載している。この機構がコストアップ要因となり、又、コストダウン設計を実施する上で大きな障害となっている。
【００１３】
従って、このような構造上の問題を回避するため、補助ガスの流れる流路の構成を改良して、傾斜に依存しない信号を得るリングセル構造に解決しなければならない課題を有する。
【００１４】
【課題を解決するための手段】
上記課題を解決するために、本発明に係る磁気式酸素測定方法及び磁気式酸素計は、次に示す構成にすることである。
【００１５】
（１）磁気式酸素測定方法は、円環形状に形成され、分流させた被測定ガスの測定側サンプル流路に磁界を形成する第１のステップ、前記分流させたそれぞれの測定側及び比較側サンプル流路の対向する位置に導通させた同一量の補助ガスを流す第１及び第２の補助ガス流路を形成する第２のステップ、前記第１及び第２の補助ガス流路のそれぞれは、前記第１及び第２の補助ガス流路より下方の補助ガス導入口から平行同一方向に分流させた第１及び第２の流路を導通する第３のステップ、前記平行同一方向に分流させた第１及び第２流路のそれぞれに第１及び第２の熱型流量センサを配置して被測定ガス中の酸素の量を測定する第４のステップ、からなる。
（２）前記第１及び第２の熱型流量センサは、自己加熱サーミスタあるいは金属あるいは半導体からなる加熱型熱線である（１）に記載の磁気式酸素測定方法。
（３）前記第１及び第２流路は、前記第１及び第２の補助ガス流路に対して直交する方向に配置したことを特徴とする（１）または（２）に記載の磁気式酸素測定方法。
【００１６】
（４）磁気式酸素計は、円環形状に形成され、分流させた被測定ガスの測定側サンプル流路に磁界を形成する磁界発生手段と、前記分流させたそれぞれの測定側及び比較側サンプル流路の対向する位置に導通させた同一量の補助ガスを流す第１及び第２の補助ガス流路と、前記第１及び第２の補助ガス流路に連通し、前記第１及び第２の補助ガス流路より下方の補助ガス導入口から平行同一方向に分流させた第１及び第２の流路と、前記平行同一方向に分流させた第１及び第２の流路のそれぞれに配置した第１及び第２の熱型流量センサと、を備えたことである。
（５）前記第１及び第２の熱型流量センサは、自己加熱サーミスタあるいは金属あるいは半導体からなる加熱型熱線である（４）に記載の磁気式酸素計。
（６）前記第１及び第２の流路は、前記第１及び第２の補助ガス流路に対して直交する方向に配置したことを特徴とする（４）または（５）に記載の磁気式酸素計。
【００１７】
このように、平行に分流された第１及び第２の流路のそれぞれにセンサを配置した構成にすることで、流路自体が傾斜してもセンサを組み込んである第１及び第２の流路も同じく傾斜することになり、その環境条件は常に一定にすることができるため、傾斜に依存しないで酸素の量を測定することが可能になる。
【００１８】
【発明の実施の形態】
次に、本発明に係る磁気式酸素測定方法及び磁気式酸素計の実施形態について、図面を参照して、以下、説明する。
【００１９】
本発明に係る磁気式酸素測定方法を具現化できる磁気式酸素計は、図１及び図２に示すように、被測定ガスを流すリングセル１１と、リングセルで検出した信号から酸素の量を検出する検出回路２０とからなる。
【００２０】
リングセル１１は、円環形状に形成されたサンプル流路１２に連通して設けた測定ガス導入口１３と、この測定ガス導入口１３の反対側に設けた測定ガス導出口１４と、測定ガス導入口１３と測定ガス導出口１４との間のサンプル流路である測定側サンプル流路１２ａに導通するように連通した第１の補助ガス流路１５ａと、第１の補助ガス流路１５ａと反対側のサンプル流路である比較側サンプル流路１２ｂに導通するように連通した第２の補助ガス流路１５ｂと、第１の補助ガス流路１５ａに連通してある測定側サンプル流路１２ａに磁界を形成するヨーク１６と、補助ガス導入口１７から枝分かれし、平行に同一方向を向き且つ所定長さに形成した第１及び第２の流路１９ａ、１９ｂと、第１の流路１９ａに配置した第１の熱型流量センサ１８ａと、第２の流路１９ｂに配置した第２の熱型流量センサ１８ｂとからなり、第１の流路１９ａは第１の補助ガス流路１５ａと直交する方向に配置されて連通し、第２の流路１９ｂは第２の補助ガス流路１５ｂと直交する方向に連通した構成になっている。この第１及び第２の熱型流量センサ１８ａ、１８ｂは、自己加熱サーミスタあるいは金属あるいは半導体からなる加熱型熱線であり、検出回路２０に接続されている。
【００２１】
検出回路２０は、第１の熱型流量センサ１８ａに接続してある第１の定抵抗回路２１ａと、第２の熱型流量センサ１８ｂに接続してある第２の定抵抗回路２１ｂと、これらの第１及び第２の定抵抗回路２１ａ、２１ｂからの信号を受信する差動増幅器２２とからなる。
【００２２】
このような構成のリングセル１１において、測定ガス導入口１３から導入された被測定ガスは二方向に分流したのち、測定ガス導出口１４へ合流するように流れる。
また、補助ガス導入口１７から導入された補助ガスは平行な第１及び第２の流路１９ａ、１９ｂを経由して、第１及び第２の熱型流量センサ１８ａ、１８ｂをそれぞれ経由し、その後、第１及び第２の補助ガス流路１５ａ、１５ｂを経由して接続部付近でそれぞれ被測定ガスと合流し、被測定ガスと共に測定ガス導出口１４へ流れる。
【００２３】
このような状況下で、被測定ガス中に酸素分子が含まれていない場合、第１の熱型流量センサ１８ａを経由する補助ガスの流量と第２の熱型流量センサ１８ｂを経由する補助ガスの流量は同一となる。
【００２４】
このため、第１の定抵抗回路２１ａに入力される第１の熱型流量センサ１８ａの出力と第２の定抵抗回路２１ｂに入力される第２の熱型流量センサ１８ｂの出力も同一となり、第１の定抵抗回路２１ａの出力信号と第２の定抵抗回路２１ｂの出力信号も同一となり、これらの出力信号の差を増幅する差動増幅器２２の出力は零になる。
【００２５】
一方、測定ガス中に酸素分子が含まれている場合、磁界印加領域における磁力作用により測定ガス中の酸素分子が引き付けられて部分流れが生じる。このため、第１の熱型流量センサ１８ａを経由する補助ガスの流量と第２の熱型流量センサ１８ｂを経由する補助ガスの流量に差が生じるようになり、第１の定抵抗回路２１ａに入力される第１の熱型流量センサ１８ａの出力信号と第２の定抵抗回路２１ｂに入力される第２の熱型流量センサ１８ｂの出力信号が同一でなくなる。従って、第１の定抵抗回路２１ａの出力信号と第２の定抵抗回路２１ｂの出力信号も異なるようになり、第１の定抵抗回路２１ａの出力信号と第２の定抵抗回路２１ｂの出力信号の差を増幅する差動増幅器２２の出力信号が測定ガス中の酸素分子量に対応した値を示すようになる。
【００２６】
さて、第１及び第２の熱型流量センサ１８ａ、１８ｂが配置してある第１及び第２の流路１９ａ、１９ｂは、平行に同一方向を向いて形成され、且つ第１及び第２の補助ガス流路１５ａ、１５ｂに直交する方向で形成されている。このことは、リングセル１１自体が傾斜、特に僅かに傾斜しても第１及び第２の流路１９ａ、１９ｂを流れる補助ガスは同一の環境を維持できるため、その流量に変化はない。従って、傾斜に依存した信号オフセットを発生することがない。
従って、図示しないが、従来技術の如くリングセル１１を平行な状態に微調整する調整機構が不要になる。
【００２７】
又、第１及び第２の熱型流量センサ１８ａ、１８ｂが配置してなる第１及び第２の流路１９ａ、１９ｂを、第１及び第２の補助ガス流路１５ａ、１５ｂと直交させて配置しているが、特に垂直方向にすれば、傾斜変化に対して鈍感な構造とすることが可能になる。即ち、垂直にすることで、オフセットがｃｏｓΘに比例する依存性をもつようになる。従って、Θの零付近の変動に対して効果を持たなくなる。
【００２８】
【発明の効果】
上記説明したように、本発明に係る磁気式酸素測定方法及び磁気式酸素計は、補助ガスが流れる流路を平行な第１及び第２の流路にし、その流路の中にそれぞれ第１及び第２の熱型流量センサを配置したことにより、傾斜変動による信号オフセットを、激減させることができ、この結果、傾斜微調整機構を省略できるので、センサ機構が簡単になり、コストダウンにつながるという効果がある。
【図面の簡単な説明】
【図１】本発明に係る磁気式酸素計を示す説明図である。
【図２】図１のＢ−Ｂ線断面図である。
【図３】従来技術における磁気式酸素計を示す説明図である。
【図４】図３のＡ―Ａ線断面図である。
【図５】図４において比較側流路が上がって傾斜した状態を示した説明図である。
【図６】図４において測定側流路が上がって傾斜した状態を示した説明図である。
【符号の説明】
１１ リングセル
１２ サンプル流路
１２ａ 測定側サンプル流路
１２ｂ 比較側サンプル流路
１３ 測定ガス導入口
１４ 測定ガス導出口
１５ａ 第１の補助ガス流路
１５ｂ 第２の補助ガス流路
１６ ヨーク
１７ 補助ガス導入口
１８ａ 第１の熱型流量センサ
１８ｂ 第２の熱型流量センサ
１９ａ 第１の流路
１９ｂ 第２の流路
２０ 検出回路。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a magnetic oxygen measuring method and a magnetic oximeter, and more particularly to a magnetic type in which an auxiliary gas flow path is improved so that the amount of oxygen gas can be detected without depending on the inclination of a ring cell. The present invention relates to an oxygen measuring method and a magnetic oximeter.
[0002]
[Prior art]
As shown in FIGS. 3 and 4, the magnetic oximeter in the prior art includes a ring cell 111 having a flow path for flowing a gas to be measured (sample gas), and a thermal flow sensor installed in the ring cell 111. The detection circuit 120 detects the flow rate of oxygen gas contained in the gas to be measured by a signal from the (thermistor).
[0003]
The ring cell 111 includes a measurement gas inlet 113 provided in communication with the sample channel 112 formed in an annular shape, a measurement gas outlet 114 provided on the opposite side of the measurement gas inlet 113, The first and second auxiliary gas flow paths 115a and 115b formed through the central position of the sample flow path 112 and communicated with each of the opposite sides, and the first and second auxiliary gas flow paths 115a, A yoke 116 (see FIG. 4) that forms a magnetic field in the measurement-side sample flow path 112a that is one side of the sample flow path 112 that communicates with 115b, and the center positions of the first and second auxiliary gas flow paths 115a and 115b The auxiliary gas introduction port 117 that communicates with the auxiliary gas and flows in the auxiliary gas, and the first and second auxiliary gas passages 115a and 115b are provided in the first and second auxiliary gas flow passages 115a and 115b at the same distance centered on the auxiliary gas introduction port 117 Beauty second thermistors 118a, has a configuration in which a 118b. The first and second thermistors 118 a and 118 b are connected to the detection circuit 120.
[0004]
The detection circuit 120 includes a first constant resistance circuit 121a connected to the first thermistor 118a, a second constant resistance circuit 121b connected to the second thermistor 118b, and the first and second of these. And a differential amplifier 122 for receiving signals from the constant resistance circuits 121a and 121b.
[0005]
In the ring cell 111 having such a configuration, the gas to be measured introduced from the measurement gas introduction port 113 is diverted in two directions and then flows so as to join the measurement gas outlet 114.
The auxiliary gas introduced from the auxiliary gas introduction port 117 is divided in two directions, and then passes through the first and second thermistors 118a and 118b, respectively, and then the first and second auxiliary gas flow paths 115a, The gas to be measured merges with the gas to be measured in the vicinity of the connection portion with 115b, and flows together with the gas to be measured to the measurement gas outlet 114.
[0006]
Under such circumstances, when oxygen molecules are not included in the gas to be measured, the flow rate of the auxiliary gas passing through the first thermistor 118a and the flow rate of the auxiliary gas passing through the second thermistor 118b are the same. .
[0007]
For this reason, the output of the first thermistor 118a input to the first constant resistance circuit 121a and the output of the second thermistor 118b input to the second constant resistance circuit 121b are also the same, and the first constant resistance circuit The output signal of 121a and the output signal of the second constant resistance circuit 121b are also the same, and the output of the differential amplifier 122 that amplifies the difference between these output signals becomes zero.
[0008]
On the other hand, when oxygen molecules are contained in the measurement gas, the oxygen molecules in the measurement gas are attracted by the magnetic force action in the magnetic field application region by the yoke 116 and a partial flow is generated. For this reason, a difference occurs between the flow rate of the auxiliary gas passing through the first thermistor 118a and the flow rate of the auxiliary gas passing through the second thermistor 118b, and the first constant resistance circuit 121a inputs the first constant resistance circuit 121a. The output signal of the thermistor 118a and the output signal of the second thermistor 118b input to the second constant resistance circuit 121b are not the same.
Accordingly, the output signal of the first constant resistance circuit 121a and the output signal of the second constant resistance circuit 121b are also different, and the output signal of the first constant resistance circuit 121a and the output signal of the second constant resistance circuit 121b are different. The output signal of the differential amplifier 122 that amplifies the difference between the two shows a value corresponding to the oxygen molecular weight in the measurement gas.
[0009]
As shown in FIG. 4, the ring cell 111 causes the same amount of gas to be diverted when the first and second auxiliary gas flow paths 115 a and 115 b that flow auxiliary gas divert from the auxiliary gas introduction port 117. There is a need. This is because the cooling state of the temperature of the first and second thermistors 118a and 118b is detected in accordance with the amount of the divided gas. Therefore, the first and second auxiliary gas flow paths 115a and 115b are installed in parallel with the auxiliary gas introduction port 117 as the center.
[0010]
[Patent Document 1]
JP-A-5-172784 (pages 2 and 3 Fig. 2)
[0011]
[Problems to be solved by the invention]
However, in the magnetic oximeter described in the prior art, it is difficult to actually install the auxiliary gas flow path in parallel. As shown in FIG. 5, when the measurement-side sample flow path 112a that generates a magnetic field is inclined downward, A large amount of heat convection of the auxiliary gas flows toward the comparison-side sample flow path 112b.
Further, as shown in FIG. 6, when the measurement-side sample flow path 112a that generates a magnetic field is inclined upward, a large amount of auxiliary gas thermal convection flows toward the measurement-side sample flow path 112a.
[0012]
As described above, a slight inclination of the ring cell 111 causes a large error (signal offset), and as a rule, a signal offset corresponding to almost full scale in the 0-1% 02 range is generated with one inclination. .
This is because the present ring cell 111 has a structure in which the ring cell 111 is formed on a plane, and the auxiliary gas to the measurement-side sample flow path 112a and the comparison-side sample flow path 112b flows in exactly the opposite direction. Because.
In such a structure, the heat generated by the first and second thermistors (self-heating thermistors) 118a and 118b inserted in the first and second auxiliary gas flow paths 115a and 115b is inclined by the flow paths. This results in adding a large offset to the signal.
This is because the current product is such that the signal offset depends on sin Θ in proportion to the inclination Θ of the first and second auxiliary gas flow paths 115a and 115b. Since the sensor is very sensitive to tilt, it is necessary to finely adjust the tilt of the ring cell 111 and level the product after installation on the site when installing an actual product.
For this reason, a complicated link mechanism that performs fine tilt adjustment from the outside of the explosion-proof container is mounted. This mechanism increases the cost, and is a major obstacle to the cost reduction design.
[0013]
Therefore, in order to avoid such a structural problem, there is a problem that the structure of the flow path through which the auxiliary gas flows is improved to solve a ring cell structure that obtains a signal that does not depend on the inclination.
[0014]
[Means for Solving the Problems]
In order to solve the above problems, a magnetic oxygen measuring method and a magnetic oxygen meter according to the present invention are configured as follows.
[0015]
(1) A magnetic oxygen measuring method includes a first step of forming a magnetic field in a measurement-side sample flow channel of a measurement gas that is formed in an annular shape and is divided, and each of the divided measurement and comparison sides A second step of forming first and second auxiliary gas flow paths for flowing the same amount of auxiliary gas conducted to opposite positions of the sample flow path, each of the first and second auxiliary gas flow paths is , A third step of conducting the first and second flow paths diverted in the same parallel direction from the auxiliary gas introduction port below the first and second auxiliary gas flow paths , the same flow in the same parallel direction. And a fourth step of measuring the amount of oxygen in the gas to be measured by disposing the first and second thermal flow sensors in the first and second flow paths, respectively.
(2) The magnetic oxygen measuring method according to (1), wherein the first and second thermal type flow sensors are self-heating thermistors or heating type hot wires made of metal or semiconductor.
(3) The magnetic type according to (1) or (2), wherein the first and second flow paths are arranged in a direction orthogonal to the first and second auxiliary gas flow paths. Oxygen measurement method.
[0016]
(4) The magnetic oximeter is formed in an annular shape and has a magnetic field generating means for forming a magnetic field in the measurement-side sample flow path of the gas to be measured, and the respective measurement-side and comparison-side samples that have been divided. first and second auxiliary gas passage supplying a flow path opposite to the same amount of auxiliary gas is conducted to the position of, communicating with the first and second auxiliary gas passage, the first and second The first and second flow paths are divided in the same parallel direction from the auxiliary gas introduction port below the auxiliary gas flow path, and the first and second flow paths are divided in the same parallel direction. The first and second thermal type flow rate sensors are provided.
(5) The magnetic oxygen meter according to (4), wherein the first and second thermal type flow sensors are self-heating thermistors or heating type hot wires made of metal or semiconductor.
(6) The magnetism according to (4) or (5), wherein the first and second flow paths are arranged in a direction orthogonal to the first and second auxiliary gas flow paths. Type oxygen meter.
[0017]
As described above, the sensor is disposed in each of the first and second flow paths that are divided in parallel, so that the first and second flows that incorporate the sensor even if the flow path itself is inclined. The road will also be inclined, and its environmental conditions can always be constant, so that it is possible to measure the amount of oxygen without depending on the inclination.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of a magnetic oxygen measuring method and a magnetic oximeter according to the present invention will be described below with reference to the drawings.
[0019]
As shown in FIGS. 1 and 2, a magnetic oximeter capable of embodying the magnetic oxygen measuring method according to the present invention includes a ring cell 11 for flowing a gas to be measured, and an amount of oxygen from a signal detected by the ring cell. And a detection circuit 20 for detection.
[0020]
The ring cell 11 includes a measurement gas inlet 13 provided in communication with a sample flow path 12 formed in an annular shape, a measurement gas outlet 14 provided on the opposite side of the measurement gas inlet 13, and a measurement gas. A first auxiliary gas channel 15a that communicates with the measurement-side sample channel 12a, which is a sample channel between the inlet 13 and the measurement gas outlet 14, and a first auxiliary gas channel 15a; A second auxiliary gas channel 15b communicating with the comparison-side sample channel 12b, which is the opposite sample channel, and a measurement-side sample channel 12a communicating with the first auxiliary gas channel 15a. The first and second flow paths 19a and 19b are branched from the auxiliary gas inlet 17 and formed in the same direction and have a predetermined length, and the first flow path 19a. 1st thermal flow rate sensor 18a and a second thermal type flow rate sensor 18b disposed in the second flow path 19b. The first flow path 19a is disposed in a direction orthogonal to the first auxiliary gas flow path 15a and communicates therewith. The second channel 19b is configured to communicate with the second auxiliary gas channel 15b in a direction orthogonal to the second auxiliary gas channel 15b. The first and second thermal type flow sensors 18 a and 18 b are self-heating thermistors or heating type heat wires made of metal or semiconductor, and are connected to the detection circuit 20.
[0021]
The detection circuit 20 includes a first constant resistance circuit 21a connected to the first thermal type flow sensor 18a, a second constant resistance circuit 21b connected to the second thermal type flow sensor 18b, and these And a differential amplifier 22 for receiving signals from the first and second constant resistance circuits 21a and 21b.
[0022]
In the ring cell 11 having such a configuration, the gas to be measured introduced from the measurement gas introduction port 13 is diverted in two directions and then flows so as to join the measurement gas outlet port 14.
The auxiliary gas introduced from the auxiliary gas introduction port 17 passes through the first and second thermal flow sensors 18a and 18b via the parallel first and second flow paths 19a and 19b, respectively. Thereafter, the gas to be measured is merged in the vicinity of the connection portion via the first and second auxiliary gas flow paths 15a and 15b, and flows to the measurement gas outlet 14 together with the gas to be measured.
[0023]
Under such circumstances, when oxygen molecules are not included in the gas to be measured, the flow rate of the auxiliary gas passing through the first thermal flow sensor 18a and the auxiliary gas passing through the second thermal flow sensor 18b. The flow rate is the same.
[0024]
For this reason, the output of the first thermal flow sensor 18a input to the first constant resistance circuit 21a and the output of the second thermal flow sensor 18b input to the second constant resistance circuit 21b are the same, The output signal of the first constant resistance circuit 21a and the output signal of the second constant resistance circuit 21b are also the same, and the output of the differential amplifier 22 that amplifies the difference between these output signals is zero.
[0025]
On the other hand, when oxygen molecules are contained in the measurement gas, the oxygen molecules in the measurement gas are attracted by the magnetic force action in the magnetic field application region, and a partial flow occurs. For this reason, a difference occurs between the flow rate of the auxiliary gas passing through the first thermal flow rate sensor 18a and the flow rate of the auxiliary gas passing through the second thermal flow rate sensor 18b, and the first constant resistance circuit 21a The output signal of the first thermal type flow sensor 18a input and the output signal of the second thermal type flow sensor 18b input to the second constant resistance circuit 21b are not the same. Accordingly, the output signal of the first constant resistance circuit 21a and the output signal of the second constant resistance circuit 21b are also different, and the output signal of the first constant resistance circuit 21a and the output signal of the second constant resistance circuit 21b are different. The output signal of the differential amplifier 22 that amplifies the difference between the two shows a value corresponding to the molecular weight of oxygen in the measurement gas.
[0026]
The first and second flow paths 19a and 19b in which the first and second thermal flow sensors 18a and 18b are arranged are formed in parallel and facing the same direction, and the first and second flow paths 19a and 19b are formed in parallel. It is formed in a direction orthogonal to the auxiliary gas flow paths 15a and 15b. This is because the auxiliary gas flowing through the first and second flow paths 19a and 19b can maintain the same environment even when the ring cell 11 itself is inclined, in particular, slightly inclined, so that the flow rate does not change. Therefore, a signal offset depending on the tilt does not occur.
Therefore, although not shown, an adjustment mechanism for finely adjusting the ring cell 11 in a parallel state as in the prior art becomes unnecessary.
[0027]
The first and second flow paths 19a and 19b in which the first and second thermal flow sensors 18a and 18b are arranged are orthogonal to the first and second auxiliary gas flow paths 15a and 15b. Although it is arranged, it is possible to make the structure insensitive to a change in inclination, particularly in the vertical direction. That is, by making it vertical, the offset has a dependency proportional to cos Θ. Therefore, it has no effect on fluctuations of Θ near zero.
[0028]
【The invention's effect】
As described above, in the magnetic oxygen measuring method and the magnetic oximeter according to the present invention, the flow paths through which the auxiliary gas flows are parallel first and second flow paths, and the first and second flow paths are respectively in the flow paths. And by arranging the second thermal flow sensor, the signal offset due to the tilt fluctuation can be drastically reduced. As a result, since the tilt fine adjustment mechanism can be omitted, the sensor mechanism is simplified and the cost is reduced. There is an effect.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing a magnetic oximeter according to the present invention.
FIG. 2 is a cross-sectional view taken along line BB in FIG.
FIG. 3 is an explanatory view showing a magnetic oximeter in the prior art.
4 is a cross-sectional view taken along line AA in FIG.
FIG. 5 is an explanatory view showing a state in which a comparison-side flow path rises and inclines in FIG. 4;
6 is an explanatory view showing a state in which a measurement-side flow path rises and is inclined in FIG. 4;
[Explanation of symbols]
11 Ring cell 12 Sample channel 12a Measurement side sample channel 12b Comparison side sample channel 13 Measurement gas inlet 14 Measurement gas outlet 15a First auxiliary gas channel 15b Second auxiliary gas channel 16 Yoke 17 Auxiliary gas Introduction port 18a First thermal flow sensor 18b Second thermal flow sensor 19a First flow path 19b Second flow path 20 Detection circuit.

Claims (6)

円環形状に形成され、分流させた被測定ガスの測定側サンプル流路に磁界を形成する第１のステップ、
前記分流させたそれぞれの測定側及び比較側サンプル流路の対向する位置に導通させた同一量の補助ガスを流す第１及び第２の補助ガス流路を形成する第２のステップ、
前記第１及び第２の補助ガス流路のそれぞれは、前記第１及び第２の補助ガス流路より下方の補助ガス導入口から平行同一方向に分流させた第１及び第２の流路を導通する第３のステップ、
前記平行同一方向に分流させた第１及び第２流路のそれぞれに第１及び第２の熱型流量センサを配置して被測定ガス中の酸素の量を測定する第４のステップ、
からなる磁気式酸素測定方法。A first step of forming a magnetic field in the measurement-side sample flow path of the gas to be measured, which is formed in an annular shape and is divided;
A second step of forming first and second auxiliary gas flow paths for flowing the same amount of auxiliary gas conducted to opposite positions of each of the divided measurement side and comparison side sample flow paths;
Each of the first and second auxiliary gas flow paths includes first and second flow paths that are branched in the same parallel direction from the auxiliary gas introduction port below the first and second auxiliary gas flow paths. A third step of conducting,
A fourth step of measuring the amount of oxygen in the gas to be measured by disposing first and second thermal flow sensors in each of the first and second flow paths branched in the same parallel direction;
A magnetic oxygen measuring method comprising: 前記第１及び第２の熱型流量センサは、自己加熱サーミスタあるいは金属あるいは半導体からなる加熱型熱線である請求項１に記載の磁気式酸素測定方法。  The magnetic oxygen measuring method according to claim 1, wherein the first and second thermal type flow rate sensors are self-heating thermistors or heating type hot wires made of metal or semiconductor. 前記第１及び第２流路は、前記第１及び第２の補助ガス流路に対して直交する方向に配置したことを特徴とする請求項１または２に記載の磁気式酸素測定方法。  The magnetic oxygen measuring method according to claim 1 or 2, wherein the first and second flow paths are arranged in a direction orthogonal to the first and second auxiliary gas flow paths. 円環形状に形成され、分流させた被測定ガスの測定側サンプル流路に磁界を形成する磁界発生手段と、
前記分流させたそれぞれの測定側及び比較側サンプル流路の対向する位置に導通させた同一量の補助ガスを流す第１及び第２の補助ガス流路と、
前記第１及び第２の補助ガス流路に連通し、前記第１及び第２の補助ガス流路より下方の補助ガス導入口から平行同一方向に分流させた第１及び第２の流路と、
前記平行同一方向に分流させた第１及び第２の流路のそれぞれに配置した第１及び第２の熱型流量センサと、
を備えたことを特徴とする磁気式酸素計。A magnetic field generating means for forming a magnetic field in the measurement-side sample flow path of the gas to be measured, which is formed in an annular shape and divided;
First and second auxiliary gas flow paths for flowing the same amount of auxiliary gas conducted to opposing positions of the divided measurement-side and comparison-side sample flow paths;
First and second flow paths communicating with the first and second auxiliary gas flow paths and diverted in the same parallel direction from an auxiliary gas introduction port below the first and second auxiliary gas flow paths; ,
First and second thermal type flow rate sensors arranged in the first and second flow paths, respectively, divided in the same parallel direction;
A magnetic oximeter characterized by comprising: 前記第１及び第２の熱型流量センサは、自己加熱サーミスタあるいは金属あるいは半導体からなる加熱型熱線である請求項４に記載の磁気式酸素計。  5. The magnetic oximeter according to claim 4, wherein the first and second thermal flow sensors are self-heating thermistors or heating hot wires made of metal or semiconductor. 前記第１及び第２の流路は、前記第１及び第２の補助ガス流路に対して直交する方向に配置したことを特徴とする請求項４または５に記載の磁気式酸素計。  6. The magnetic oximeter according to claim 4, wherein the first and second flow paths are arranged in a direction orthogonal to the first and second auxiliary gas flow paths.
JP2003123289A 2003-04-28 2003-04-28 Magnetic oxygen measuring method and magnetic oxygen meter Expired - Fee Related JP4009952B2 (en)

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