JP2005526978A - Apparatus and method for measuring gas concentration by single absorption line measurement - Google Patents
Apparatus and method for measuring gas concentration by single absorption line measurement Download PDFInfo
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- 238000005259 measurement Methods 0.000 title claims abstract description 47
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Abstract
本発明は、レーザー(2a)を用い、プロセスガスを収容した容器(1)内を通過する光路にレーザー(2a)を導いてプロセスガスの少なくとも一つの成分の濃度を測定する装置と方法に関する。本発明は、光路の一部の区間ではレーザーがプロセスガスから遮蔽されることなくプロセスガス中を通過するように自由空間中に導かれていると共に光路の他の区間ではレーザーがプロセスガスから遮蔽されるように遮蔽体内に導かれていることを特徴とする。自由空間中を通過するレーザー光路区間のみが測定区間(4)として画定され、この測定区間がレーザー分光分析による単一吸収線の分光測定に用いられる。The present invention relates to an apparatus and method for measuring the concentration of at least one component of a process gas by using a laser (2a) and guiding the laser (2a) to an optical path passing through a container (1) containing a process gas. In the present invention, the laser is guided into the free space so as to pass through the process gas without being shielded from the process gas in a part of the optical path, and the laser is shielded from the process gas in another part of the optical path. It is characterized by being guided into the shielding body. Only the laser beam path section that passes through the free space is defined as the measurement section (4), and this measurement section is used for spectroscopic measurement of a single absorption line by laser spectroscopic analysis.
Description
本発明は、レーザーを用い、プロセスガスを収容した容器内を通過する光路にレーザーを導いてプロセスガスの少なくとも一つの成分の濃度を測定する装置及び方法に関するものである。 The present invention relates to an apparatus and method for measuring the concentration of at least one component of a process gas by using a laser and guiding the laser to an optical path passing through a container containing a process gas.
混合ガスの個々の成分濃度をレーザーを用いて分光測定する測定方法及び測定装置は公知である。 A measuring method and a measuring apparatus for performing spectroscopic measurement of individual component concentrations of a mixed gas using a laser are known.
しかしながら、粉塵を随伴するプロセスガス（混合ガス）における成分濃度の測定にレーザー分光分析法を利用する場合、公知の方法では粉塵粒子によって生起されるレーザー光の吸収や反射散乱による制約を受けることが多い。比較的多量の粉塵を随伴し、しかも測定区間が長い場合、例えば横断面積の大きな管を横切るような測定区間の場合には、測定区間長を越えて検知器に到達するレーザー光の強度が激減し、検知器からは利用可能な信号が出力されなくなる。従って、このような用途には公知の方法は適合しない。 However, when laser spectroscopy is used to measure the concentration of components in a process gas (mixed gas) that accompanies dust, known methods may be limited by the absorption or reflection scattering of laser light caused by dust particles. Many. When a relatively large amount of dust accompanies and the measurement section is long, for example, a measurement section that crosses a tube with a large cross-sectional area, the intensity of the laser beam that reaches the detector beyond the measurement section length is drastically reduced. However, no usable signal is output from the detector. Therefore, known methods are not suitable for such applications.
上述のような応用の要求は、金属加工技術、或いはエネルギー生産及び発電所技術の領域で比較的頻繁に発生する。即ち、これらの技術領域では粉塵で汚染されたプロセスガスが大量に副生され、装置を運転する者にとってプロセスガスの組成が大きな関心事だからである。 Such application requirements occur relatively frequently in the areas of metalworking technology, or energy production and power plant technology. That is, in these technical areas, a large amount of process gas contaminated with dust is produced as a by-product, and the composition of the process gas is of great concern to the person who operates the apparatus.
従って本発明の主要な課題は、プロセスガスの成分濃度をレーザー分光測定するための改良された方法及び装置を提供することであり、特に粉塵を随伴する大きな体積流量のプロセスガスに対しても好適な気体濃度分光測定装置及び方法を提供することである。 Accordingly, a major object of the present invention is to provide an improved method and apparatus for laser spectroscopic measurement of process gas component concentrations, and is particularly suitable for large volume flow process gases associated with dust. Gas concentration spectrometer and method are provided.
この課題は、装置に関しては、レーザー光の光路の一部の区間ではレーザーがプロセスガスから遮蔽されることなくプロセスガス中を通過するように自由空間中に導かれていると共に前記光路の他の区間ではレーザーがプロセスガスから遮蔽されるように遮蔽体内に導かれており、前記自由空間中を通過するレーザー光路区間のみが単一吸収線を分光測定するための測定区間(4)として画定されていることによって解決される。この方式には、或る領域を端から端まで連続的に測定する分光測定（走査法）に比べ、格段に高い測定精度が得られるという利点がある。本発明では、いわゆる単一吸収線分光分析法を適用する。従って、波長が予め定められた設定値に固定されているか固定可能であり、しかも波長が正確に維持されるようなレーザー装置を使用するのことが好ましい。例えば、一酸化炭素の測定には、波長が正確に定義された赤外線レーザーが使用される。これに対して走査型レーザー、即ち、予め定められた手順に従って或る波長領域を端から端まで連続的に測定（走査）するレーザー装置は、本発明の目的である高い精度には適さない。本発明では、単一の周波数だけに固定された単一吸収線分光測定法を用いるので、特別な補助手段なしにレーザーの連続的な自動較正が可能である。これに対し、走査型レーザーの場合には一種又は複数種の対照ガスが必要であり、これは対照ガスを用いてレーザーを連続的に較正しなければならないためである。 This problem is related to the apparatus. In some sections of the optical path of the laser light, the laser is guided into free space so as to pass through the process gas without being shielded from the process gas, and other parts of the optical path. In the section, the laser is guided into the shielding body so as to be shielded from the process gas, and only the laser light path section passing through the free space is defined as a measurement section (4) for spectroscopic measurement of a single absorption line. It is solved by being. This method has an advantage that a much higher measurement accuracy can be obtained compared to spectroscopic measurement (scanning method) in which a certain region is continuously measured from end to end. In the present invention, so-called single absorption line spectroscopy is applied. Therefore, it is preferable to use a laser device in which the wavelength is fixed or can be fixed to a predetermined set value and the wavelength is accurately maintained. For example, an infrared laser having a precisely defined wavelength is used for measuring carbon monoxide. In contrast, a scanning laser, that is, a laser apparatus that continuously measures (scans) a certain wavelength region from end to end in accordance with a predetermined procedure is not suitable for the high accuracy that is the object of the present invention. The present invention uses single absorption line spectroscopy fixed to only a single frequency, so that continuous automatic calibration of the laser is possible without special assistance. In contrast, a scanning laser requires one or more control gases because the laser must be continuously calibrated using the control gas.
本発明において、前記光路の他の区間でレーザーをプロセスガスから遮蔽するための遮蔽体は中空体によって構成されていることが好ましい。また、この遮蔽体の領域には、遮蔽体、特に中空体の内部からプロセスガスを掃気するための洗滌ガス供給手段が設けられていることが更に好ましく、それによって遮蔽体の内部に既知の組成の汚染されていないガスで満たせば、レーザー光は殆ど強度の低下なしに洗滌ガス中を通過し、従ってこの洗滌ガスは濃度測定に対して実質的に影響を及ぼさないか、或いは既知の組成に基いて事後に測定値からその影響分を消去し得る利点が得られる。洗滌ガスとしては、例えば窒素ガスが極めて優れている。一般的には、その他の種々の不活性ガスも洗滌ガスとして適当と考えられる。或るガスが洗滌ガスとして適当であるか否かは、特にプロセスガスのどの成分を測定対象とするかによって決定され得るものである。 In this invention, it is preferable that the shielding body for shielding a laser from process gas in the other area of the said optical path is comprised with the hollow body. Further, it is more preferable that a cleaning gas supply means for scavenging process gas from the inside of the shielding body, particularly the hollow body, is provided in the area of the shielding body, whereby a known composition is provided inside the shielding body. When filled with uncontaminated gas, the laser light passes through the cleaning gas with almost no decrease in intensity, so that the cleaning gas has virtually no effect on the concentration measurement or has a known composition. Based on this, the advantage can be obtained that the influence can be eliminated from the measured value after the fact. As the cleaning gas, for example, nitrogen gas is extremely excellent. In general, various other inert gases are considered suitable as cleaning gases. Whether or not a gas is suitable as a cleaning gas can be determined in particular depending on which component of the process gas is to be measured.
本発明の有利な一実施形態では、遮蔽体は管状に形成されている。遮蔽体は水冷ランスとして構成されていると特に有利である。このような実施形態によれば、本発明による濃度測定を非常に高温のプロセスガスにも問題なく適用することが可能となる。 In one advantageous embodiment of the invention, the shield is formed in a tubular shape. It is particularly advantageous if the shield is configured as a water-cooled lance. According to such an embodiment, the concentration measurement according to the present invention can be applied to a very high temperature process gas without any problem.
本発明の別の有利な一実施形態では、遮蔽体は耐熱性及び／又は耐酸性を有する材料によって構成されている。この場合、遮蔽体をセラミック材料で構成することが有利である。これらの材料により、困難な条件下、例えばプロセスガスに酸性成分が含有されている場合にも、本発明による濃度測定を問題なく適用することが可能となる。 In another advantageous embodiment of the invention, the shield is constituted by a material having heat resistance and / or acid resistance. In this case, it is advantageous that the shield is made of a ceramic material. With these materials, the concentration measurement according to the present invention can be applied without any problem even under difficult conditions, for example, when an acidic component is contained in the process gas.
本発明の更に別の一実施形態では、レーザー光源の射出光路側と、該レーザー光源からのレーザーを受光する検知器の入射光路側との双方にそれぞれ遮蔽体が取り付けられ、これら遮蔽体によって測定区間が両側から限定されている。この実施形態では、特に測定に対する周縁効果（ガス体積部分の周縁領域における影響）を弱めることができるという利点が得られる。周縁効果による妨害は、例えば流動しているプロセスガスにおいて現われることがある。 In still another embodiment of the present invention, shields are attached to both the emission light path side of the laser light source and the incident light path side of the detector that receives the laser from the laser light source, and measurement is performed by these shields. The section is limited from both sides. In this embodiment, there is an advantage that the peripheral effect (influence in the peripheral region of the gas volume portion) on the measurement can be particularly weakened. Interferences due to peripheral effects can appear, for example, in flowing process gases.
方法に関して言えば、前述の課題は、レーザー光の光路の一部の区間ではレーザーをプロセスガスから遮蔽することなくプロセスガス中の自由空間に導くと共に前記光路の他の区間ではレーザーをプロセスガスから遮蔽する遮蔽体内に導き、前記自由空間中を通過するレーザー光路区間のみを測定区間としてレーザーによる前記成分の濃度の分光測定に用い、前記測定区間における単一吸収線の分光測定を行うことによって解決される。このような方法によれば、測定区間が長大になりがちな場合でも遮蔽体によって限定でき、また粉塵の随伴などで汚染されたプロセスガスや、或いは全般的に微粒子が混入したプロセスガスなどについても、高精度で信頼できる測定が可能になる。この場合、プロセスガスは高温であっても問題はなく、それは、高温の場合に予想される水蒸気の吸収バンドも単一吸収線による本発明の測定（単一線分光分析）には妨げとなるような影響を全く受けないからである。 Regarding the method, the aforementioned problem is that the laser beam is guided to a free space in the process gas without shielding from the process gas in a part of the optical path of the laser beam, and the laser is separated from the process gas in the other part of the optical path. Solved by conducting a spectroscopic measurement of the single absorption line in the measurement section, using only the laser optical path section that passes through the free space as a measurement section and is used for the spectroscopic measurement of the concentration of the component by the laser. Is done. According to such a method, even when the measurement section tends to be long, it can be limited by the shield, and also for a process gas contaminated by the accompanying dust or a process gas mixed with fine particles in general. Highly accurate and reliable measurement is possible. In this case, there is no problem even if the process gas is at a high temperature, and the absorption band of water vapor expected at a high temperature also hinders the measurement of the present invention using a single absorption line (single line spectroscopic analysis). It is because it is not affected at all.
遮蔽体は、洗滌ガスで掃気することが好ましい。洗滌ガスとしては窒素が特に有利に使用可能である。この洗滌ガスによる掃気により、遮蔽体の内部には既知の組成の汚染されていないガスが存在することにあると言う利点がもたらされる。この洗滌ガスはレーザー光を殆ど強度の低下なく通過させ、濃度測定に対しては無影響の挙動をとる。即ち、例えば洗滌月として窒素ガスを用いた場合は、窒素化合物の濃度測定を行う場合でない限り、測定結果には全く影響が現れない。一般的に言えば、或る気体が洗滌ガスとして適当であるか否かは、プロセスガスのいかなる成分の濃度を測定するかによって決まる。通常は、濃度測定の対象成分ガスとスペクトル的に著しく異なるガスを洗滌ガスとして選択することが望ましい。 The shield is preferably scavenged with a cleaning gas. Nitrogen can be used particularly advantageously as the cleaning gas. This scavenging of the cleaning gas provides the advantage that there is an uncontaminated gas of known composition inside the shield. This cleaning gas allows the laser light to pass through with almost no decrease in intensity and behaves unaffected for concentration measurement. That is, for example, when nitrogen gas is used as a washing month, there is no influence on the measurement result unless the concentration of nitrogen compound is measured. Generally speaking, whether a gas is suitable as a cleaning gas depends on what component concentration of the process gas is measured. Normally, it is desirable to select a gas that is spectrally significantly different from the target component gas for concentration measurement as the cleaning gas.
窒素以外の種々の不活性ガスも洗滌ガスとして好適に使用することができる。不活性ガスの場合の特別な利点は、洗滌ガスとプロセスガスとの間の化学反応を排除できることである。 Various inert gases other than nitrogen can also be suitably used as the cleaning gas. A special advantage in the case of inert gases is that chemical reactions between the cleaning gas and the process gas can be eliminated.
本発明により測定法の別の有利な実施形態では、洗滌ガスとして大気が使用される。この実施形態には、特にプロセスのコストを低廉化できると言う利点がある。但し、測定区間中に大気が存在すると望ましくない場合もある。例えば、各種の燃焼排気ガス中の一酸化炭素濃度を測定する場合に大気を洗滌ガスとして使用すると、本来の測定の妨害になる可能性があり、従ってこの場合には窒素を洗滌ガスとして用いるとよい。 In another advantageous embodiment of the measuring method according to the invention, the atmosphere is used as cleaning gas. This embodiment has the advantage that the cost of the process can be reduced. However, it may not be desirable if air exists in the measurement section. For example, when measuring the carbon monoxide concentration in various combustion exhaust gases, if the atmosphere is used as a cleaning gas, it may interfere with the original measurement. Therefore, in this case, if nitrogen is used as the cleaning gas, Good.
同様に、例えばプロセスガス中の酸素濃度を測定する場合も、洗滌ガスとしては窒素が好ましい。 Similarly, for example, when measuring the oxygen concentration in the process gas, nitrogen is preferable as the cleaning gas.
更に本発明は、濃度測定に比較的低出力のレーザーを使用し得る利点を有する。なぜなら、本発明に従って光路の一部に測定対象ガスからの遮蔽が行われるため、遮蔽を行わない測定方式に比べて測定区間長が縮小されるからである。それに加えて、低出力のレーザーを使用することによってプロセスガス中のレーザー光エネルギーによって誘発され得る好ましくないプロセスガスの変性ないし変質が少なくなる利点もある。 Furthermore, the present invention has the advantage that a relatively low power laser can be used for concentration measurement. This is because according to the present invention, since the shielding from the measurement target gas is performed on a part of the optical path, the measurement section length is reduced as compared with the measurement method in which the shielding is not performed. In addition, the use of a low power laser has the advantage of reducing undesirable process gas denaturation or alteration that can be induced by laser light energy in the process gas.
本発明とその目的及び利点の更なる詳細について図示の実施例によって以下に詳しく説明する。この場合、図面は一つだけであり、プロセスガスを収容した容器の断面を示している。 Further details of the invention and its objects and advantages are explained in more detail below by means of an illustrative embodiment. In this case, there is only one drawing and shows a cross section of the container containing the process gas.
即ち、図１はプロセスガスを収容した容器１の断面を示し、この容器は管状の管壁を備えている。この管状容器は管壁の一方の側にレーザー光源２ａを、またそれに向き合ってレーザー受光検知器２ｂを備え、レーザー光源から射出されて容器１内を横断したレーザー光の強度を検知器２ｂで受光検出し、図示しない測定装置によりレーザー光の受光強度を記録するようになっている。レーザー光源２ａから受光検知器までのレーザー光の光路は、容器内のプロセスガスから遮蔽されるように部分的に二つの遮蔽体３によって取り囲まれており、これらの遮蔽体がレーザー光源２ａの射出光路側と受光検知器２ｂの入射光路側との双方から隔てられた限定領域に測定区間４を画定している。これらの遮蔽体２には、好ましくは洗滌ガス（例えば窒素）を供給する図示しないノズル手段が設けられる。
That is, FIG. 1 shows a cross section of a
容器１は、例えば高温のプロセスガス（例えば製鉄所の炉から出る排気ガス）で満たされた管路又は該管路に接続された測定用容器であり、本実施例ではガス温度は８００℃以上であり、ガス中の一酸化炭素濃度を測定すべく意図されている。この目的で、二つの水冷構造のセラミック管３から成る遮蔽体が使用されている。洗滌ガスとしては窒素ガスが使用され、例えば冷却水を通すコイル状管（図示されていない）で冷却されるセラミック管３の内部からプロセスガスを掃気して排除するのに用いられる。
The
本発明において、遮蔽体３の長さ寸法は、レーザー光源２ａと受光検知器２ｂとの間隔寸法に応じて測定区間４が例えば１０cm〜３０cmの長さとなるようにするとよい。測定区間４の長さ寸法としては約２０cmが特に好ましいことが判っている。
In the present invention, the length of the
レーザー光源は例えば波長調整可能なレーザー装置であり、本発明に従って測定に先立って選定された単一の周波数で運転される。波長調整可能なレーザー装置には、その調整可能な周波数範囲から測定対象のガス成分によって良好に吸収される周波数（波長）を選定できる利点がある。この場合、選択した波長の吸収線の強度低下がプロセスガス中の測定すべきガス成分の濃度の尺度となることは述べるまでもない。 The laser light source is, for example, a wavelength tunable laser device that is operated at a single frequency selected prior to measurement in accordance with the present invention. The wavelength-adjustable laser device has an advantage that a frequency (wavelength) that is favorably absorbed by the gas component to be measured can be selected from the adjustable frequency range. In this case, it goes without saying that the decrease in the intensity of the absorption line of the selected wavelength is a measure of the concentration of the gas component to be measured in the process gas.
尚、レーザー光源として測定対象のガス成分に適合した周波数で発振煤単一モードのレーザー装置又はデバイスを使用することも可能である。 In addition, it is also possible to use a laser device or device of an oscillation single mode at a frequency suitable for the gas component to be measured as a laser light source.
本発明のレーザーによる気体成分の濃度測定は、管路を流れるガスに対する連続測定法として特に有利に実施することができる。但し、本発明の別の実施形態においては、不連続的な濃度測定も成功裏に実施することが可能である。 The concentration measurement of the gas component by the laser of the present invention can be carried out particularly advantageously as a continuous measurement method for the gas flowing through the pipe. However, in another embodiment of the invention, discontinuous concentration measurements can also be successfully performed.
Claims (11)
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE10223239A DE10223239A1 (en) | 2002-05-24 | 2002-05-24 | Device and method for spectroscopic measurement of a gas concentration by determining a single absorption line |
| PCT/EP2003/005296 WO2003100392A1 (en) | 2002-05-24 | 2003-05-20 | Device and method for spectroscopically measuring a gas concentration by determining a single absorption line |
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| JP2005526978A true JP2005526978A (en) | 2005-09-08 |
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| EP (1) | EP1508030A1 (en) |
| JP (1) | JP2005526978A (en) |
| KR (1) | KR20050013552A (en) |
| AU (1) | AU2003238366A1 (en) |
| BR (1) | BR0311244A (en) |
| DE (1) | DE10223239A1 (en) |
| RU (1) | RU2004138074A (en) |
| WO (1) | WO2003100392A1 (en) |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2014094355A (en) * | 2012-11-09 | 2014-05-22 | Mitsubishi Heavy Ind Ltd | Exhaust gas denitrification system, and regeneration method and catalyst replacement method in exhaust gas denitrification device |
| JP2014100630A (en) * | 2012-11-16 | 2014-06-05 | Mitsubishi Heavy Ind Ltd | Exhaust gas denitrification system |
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| DE2340747A1 (en) * | 1972-10-26 | 1974-05-09 | Bailey Meter Co | GAS ANALYZER |
| US3838925A (en) * | 1972-12-07 | 1974-10-01 | Baldwin Electronics Inc | Photoelectric opacity measuring system |
| US4076425A (en) * | 1976-02-17 | 1978-02-28 | Julian Saltz | Opacity measuring apparatus |
| US4225243A (en) * | 1978-06-26 | 1980-09-30 | Measurex Corporation | Gas measuring apparatus with standardization means, and method therefor |
| US4247205A (en) * | 1979-02-02 | 1981-01-27 | Measurex Corporation | Gas measuring apparatus with standardization means, and method therefor |
| GB2066947B (en) * | 1980-01-09 | 1984-06-20 | Measurex Corp | Gas measuring apparatus with adjustable path length and method for operation and standardization therefor |
-
2002
- 2002-05-24 DE DE10223239A patent/DE10223239A1/en not_active Withdrawn
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2003
- 2003-05-20 JP JP2004507803A patent/JP2005526978A/en active Pending
- 2003-05-20 AU AU2003238366A patent/AU2003238366A1/en not_active Abandoned
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- 2003-05-20 WO PCT/EP2003/005296 patent/WO2003100392A1/en active Application Filing
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2014094355A (en) * | 2012-11-09 | 2014-05-22 | Mitsubishi Heavy Ind Ltd | Exhaust gas denitrification system, and regeneration method and catalyst replacement method in exhaust gas denitrification device |
| JP2014100630A (en) * | 2012-11-16 | 2014-06-05 | Mitsubishi Heavy Ind Ltd | Exhaust gas denitrification system |
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| EP1508030A1 (en) | 2005-02-23 |
| DE10223239A1 (en) | 2003-12-04 |
| AU2003238366A1 (en) | 2003-12-12 |
| WO2003100392A1 (en) | 2003-12-04 |
| KR20050013552A (en) | 2005-02-04 |
| ZA200410367B (en) | 2006-06-28 |
| BR0311244A (en) | 2005-03-15 |
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