JP3374134B2 - Infrared gas analyzer - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared gas analyzer. 2. Description of the Related Art When a plurality of types of gases are sequentially introduced into one sample line (sample cell), it is necessary to measure only a specific gas. Although it is necessary to determine whether or not the target gas has been introduced into the sample line, the determination method has not yet been established. Conventionally, in one optical system, measurement of only one component is common, and when measuring several types of components, a plurality of optical systems are required. For example, a non-dispersive infrared gas analyzer (Non Di
spersive Infrared Analyze
r) is generally one-path, one-component detection. When measuring a plurality of components, two optical paths 2 are used even in the case of the single cell method.
Component detection is required, which requires a large number of optical system parts. Further, for simultaneous measurement of three or four components, the gas analyzer unit can also be used by using a cross-modulation single cell system in which a sample gas and a comparison gas are alternately introduced into two measurement cells via a rotary valve. And two sample gas flow rates from the sampling device need to be prepared. Therefore, the product cost is high, such as an increase in the number of optical system components and the complexity of the sampling system. At the same time, maintenance of a plurality of analyzers is required, and the running cost is also high. [0003] The present invention has been made in consideration of the above-mentioned matters, and an object of the present invention is to measure one gas to be measured.
An object of the present invention is to provide an infrared gas analyzer capable of determining whether or not the sample gas has been introduced into one sample cell. [0004] In order to achieve the above object, an infrared gas analyzer of the present invention is provided with a light source on one side of a cell and a gas to be measured on the other side. A gas filter filled with the same gas and a comparison filter filled with a gas having no infrared absorption involved in the measurement are provided in parallel with each other and in series with the cell. A detector is further provided, and a mirror is provided at the subsequent stage of the comparison filter so as to be capable of switching in and out of an optical path, and when this mirror is in an optical path, light transmitted through the comparison filter is transmitted to the mirror and It is characterized in that it is configured to be guided to a solid state detector via a light splitting means. In the infrared gas analyzer configured as described above, when the mirror is in the optical path, the light transmitted through the comparison filter can be guided to the solid state detector via the mirror and the light splitting means. The signal amount caught by the solid state detector can be obtained as the sum of the signal amount due to the light transmitted through the comparison filter and the signal amount due to the light transmitted through the gas filter, while when the mirror is not in the optical path. Thus, the signal amount by the light transmitted only through the gas filter is obtained. Therefore, whether or not the gas introduced into the cell is the gas to be measured is determined based on the signal amount obtained when the mirror is on the optical path and the signal amount obtained when the mirror is not on the optical path. This is done from the ratio or difference. In addition, after the determination, the concentration of the gas to be measured can be obtained by calculating the concentration of the signal of the solid state detector. In addition, in the present invention, the solid-state detector for measurement and the solid-state detector for comparison are shared by a single solid-state detector. There is no individual difference due to. Therefore, S /
There is an advantage that N can be improved. Embodiments of the present invention will be described below with reference to the drawings. Fig. 1 shows a single-cell system, in which two solid state detectors are used for measurement and comparison, and a gas filter containing the gas to be measured is installed upstream of the solid state detector for comparison. A first embodiment is shown in which the outputs of the solid state detectors are compared to determine whether or not the gas introduced into the cell is the gas to be measured and to measure the concentration thereof. In FIG. 1, the infrared gas analyzer is provided with a light source 2 on one side of a cell 1 and a chamber 4 containing a half mirror (an example of a light dividing means) 3 on the other side.
On one optical path A side of the half mirror 3, a measurement solid state detector 5 is provided, and on the other optical path B side, the same gas G as the gas to be measured is provided.
Filter 6 and solid detector 7 for comparison
Are provided respectively. Reference numeral 8 denotes an inlet for the sample gas S provided in the cell 1, and reference numeral 9 denotes an outlet for the sample gas S provided in the cell 1. Further, the half mirror 3 is provided in the chamber 4 with its transmission / reflection surface 3a having an inclination angle of 45 ° with respect to the optical paths A and B, respectively. The division ratio of the amount of light to the solid state detectors 5 and 7 for measurement and comparison by the half mirror 3 is normally used at 1: 1. The amount of light corresponding to the detection sensitivity of the solid-state detectors 5 and 7 may be distributed using a material whose reflectance is adjusted and having a ratio of 1: 2 or more. [0010] In the infrared gas analyzer configured as described above,
The sample gas S is sequentially sent to the cell 1, and the change in the amount of light with respect to the measurement component (gas to be measured) absorbed by the cell 1 is equally divided into the measurement and comparison solid state detectors 5 and 7 by the half mirror 3. And the signals of the solid state detectors 5 and 7 are
It is amplified and output as appropriate. The gas G, which is the same as the measurement component, is sealed in the gas filter cell 6. For this reason, the ratio or difference in signal amount between the case where the same type of gas as the gas filled in the gas filter 6 is introduced and the case where a different type of gas is introduced into the cell 1 changes. Alternatively, it is determined whether or not the gas introduced into the cell 1 is the gas to be measured based on the difference. Moreover, after the determination, the concentration of the gas to be measured is obtained by calculating the concentration of the signal of the solid state detector 5 for measurement. The solid state detector 5 for measurement may be arranged on the transmission position side of the half mirror 3, and the gas filter 6 and the solid state detector 7 for comparison may be arranged on the reflection position side. FIG. 2 shows a single-cell system in which two solid state detectors are used for measurement and comparison, and a gas filter containing a gas to be measured is installed upstream of the solid state detector for comparison. Further, a second embodiment in which the chamber of the half mirror and the gas filter are used is shown. FIG. 2 differs from the first embodiment only in that a part of the inside of the chamber 4 of the half mirror 3 is used as a gas filter 6. The solid state detector 5 for measurement is provided on the transmission position side of the half mirror 3 and the gas filter 6 is provided on the reflection position side.
And a comparison solid state detector 7 may be provided. FIG. 3 shows a single cell system, in which two solid state detectors are used for measurement and comparison, and a plurality of gases each having a different gas to be measured sealed upstream of the solid state detector for comparison. A third embodiment in which a filter is installed and a gas filter is provided so as to be movable in a direction parallel to the optical path is shown. In this embodiment, a plurality of gas filters 6,
Since 6, 6 are provided so as to be movable in a direction parallel to the optical path B,
The same gas G, H,
By simply enclosing M, it is possible to automatically introduce a plurality of measurement target gases simply by preparing one comparative solid state detector 7 without preparing the same number of comparative solid state detectors as the number of gas filters. It is possible to determine whether or not they are present and to measure their concentration. FIG. 4 shows that a single solid state detector, a plurality of gas filters and a plurality of solid state detectors for comparison are installed, and a single cell system can simultaneously detect two or more components of a gas to be measured. A fourth embodiment in which the influence of an interference gas component that interferes with the detection of a target gas component can be compensated will be described. In FIG. 4, the infrared gas analyzer has a light source 2 on one side of a cell 1 and a plurality of half mirrors (an example of a light splitting means) 3, 3 on the other side. The solid-state detector 5 for measurement is provided on one optical path B side of the last half mirror 3 and the same gas as the gas to be measured is provided on the other optical path A side of the last half mirror 3. A gas filter 6 enclosing G and a solid state detector 7 for comparison are provided respectively, and the same as the gas to be measured is provided on the optical path C side of the half mirror 3 other than the rearmost half mirror 3 in the direction orthogonal to the serial direction. A gas filter 6 containing a gas H and a solid state detector 7 for comparison are provided. In this embodiment, a plurality of gas filters 6, 6 and a plurality of solid state detectors 7, 7 for comparison are provided. Therefore, after determining whether or not the gas introduced into the cell 1 is the gas to be measured, the concentration of the gas to be measured is calculated. In this embodiment, two or more measurement target gases can be simultaneously detected. That is,
In performing the signal processing from the measurement solid state detector 5, the concentration calculation processing corresponding to each of a plurality of kinds of measurement target gases is selected to calculate the concentration. As a result, in one optical system, by switching the concentration calculation process, two or more measurement target gases can be simultaneously detected. Further, the infrared gas analyzer of this embodiment has a function of compensating for the influence of an interference gas component which interferes with the detection of each gas component to be measured. That is, since a plurality of the gas filters 6, 6 and the comparative solid state detectors 7, 7 are provided, the signal amounts of the respective comparative solid state detectors 7, 7 can be obtained separately and in real time. Therefore, the compensation calculation can be performed by using the signal amount from each comparison solid state detector 7. FIG. 5 shows the solid state detector 5 for measurement in FIG.
4 shows an embodiment in which the positions of the gas filter 6 and the solid state detector 7 for comparison are exchanged, and similarly to the fourth embodiment shown in FIG. 4, two or more measurement target gases can be detected simultaneously. In addition, it is possible to compensate for the influence of the interference gas component that interferes with the detection of each measurement target gas component. FIG. 6 shows an embodiment of the present invention in which one solid state detector 21 is used for both the measurement solid state detector 5 and the comparison solid state detector 7 used in each of the above embodiments. In FIG. 6, the infrared gas analyzer is provided with a light source 2 on one side of a cell 1 and a gas filter 22 containing the same gas G as the gas to be measured on the other side, and is involved in the measurement. A comparison filter 23 filled with a gas having no infrared absorption is provided in parallel with each other and in series with the cell 1, and a half mirror (an example of a light splitting unit) 24 and a solid state detector 21 are provided behind the gas filter 22. Further, a mirror 25 is provided downstream of the comparison filter 23 so as to be capable of switching in and out of the optical path D.
Is incident on the optical path D, the light transmitted through the comparison filter 23 is guided to the solid state detector 21 via the mirror 25 and the half mirror 24. In this embodiment, when the mirror 25 enters the optical path D, the light transmitted through the comparison filter 23 is transmitted through the mirror 25 and the half mirror 24 to the solid state detector 21.
Therefore, the signal amount caught by the solid state detector 21 can be obtained as the sum of the signal amount due to the light transmitted through the comparison filter 23 and the signal amount due to the light transmitted through the gas filter 22. When the mirror 25 is not in the state of entering the optical path D, a signal amount is obtained only by the light transmitted through the gas filter 22 on the optical path E. Therefore, whether the gas introduced into the cell 1 is the gas to be measured is determined based on the signal amount obtained when the mirror 25 is on the optical path D and when the mirror 25 is not on. This is performed based on the ratio or difference between the signal amounts. Moreover, after the determination, the concentration of the gas to be measured can be obtained by calculating the concentration of the signal of the solid state detector 21. Further, since the solid state detector 21 is also used as the solid state detector 5 for measurement and the solid state detector 7 for comparison, the solid state detector 21 for measurement and the solid state detector 7 for comparison are compared when each is used separately. Therefore, there is no individual difference due to detector characteristics.
Therefore, there is an advantage that S / N can be improved. Note that the mirror 25 may be a reflecting mirror or a half mirror. Further, as the solid state detector used in each of the above embodiments, a sensor having no wavelength selectivity, such as a pyrosensor, a thermopile sensor, or a semiconductor sensor, can be used. As described above, according to the present invention, when the mirror is in the optical path, the light transmitted through the comparison filter is transmitted to the solid state detector via the mirror and the light splitting means. The signal amount caught by the solid state detector can be obtained as the sum of the signal amount due to the light transmitted through the comparison filter and the signal amount due to the light transmitted through the gas filter. On the other hand, when it is not in the input state, it is possible to obtain the signal amount by the light transmitted only through the gas filter. Therefore, whether or not the gas introduced into the cell is the gas to be measured is determined based on the signal amount obtained when the mirror is on the optical path and the signal amount obtained when the mirror is not on the optical path. From the ratio or the difference. Moreover, after the determination, the signal of the solid state detector is subjected to arithmetic processing to obtain the concentration of the gas to be measured. In addition, in the present invention, the solid-state detector for measurement and the solid-state detector for comparison are shared by a single solid-state detector. There is no individual difference due to. Therefore, S / N is improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram of the entire configuration showing a first embodiment. FIG. 2 is an explanatory diagram of the entire configuration showing a second embodiment. FIG. 3 is an explanatory diagram of the entire configuration showing a third embodiment. FIG. 4 is an explanatory diagram of the overall configuration showing a fourth embodiment. FIG. 5 is an explanatory view of the overall configuration showing a fifth embodiment. FIG. 6 is an explanatory diagram of the entire configuration showing an embodiment of the present invention. [Description of Signs] 1 cell, 2 light source, 21 solid detector, 22 gas filter, 23 comparison filter, 24 light splitting means, 25
... mirror, D ... optical path, G ... same gas as the gas to be measured.

Continuation of the front page (72) Inventor Yoneda's advantage 2 Higashi-cho, Kichijoin-miya, Minami-ku, Kyoto, Kyoto Inside Horiba, Ltd. (56) References JP-A-5-10874 (JP, A) JP-A-5-45286 (JP, A) JP-A-6-241998 (JP, A) JP-A-5-215683 (JP, A) US Patent 3,811,776 (US, A) US Patent 3,571,589 (US, A) (58) Fields investigated ( Int.Cl. ⁷ , DB name) G01N 21/00-21/61 JICST file (JOIS)

Claims (1)

(57) [Claims 1] A light source is provided on one side of a cell, and a gas filter containing the same gas as the gas to be measured is enclosed on the other side, and an infrared absorption filter involved in the measurement is provided. A comparison filter filled with no gas is provided in parallel with each other and in series with the cell, a light splitting means and a solid state detector are provided on the downstream side of the gas filter, and an optical path is provided on the downstream side of the comparison filter. A mirror is provided so as to be capable of switching in and out of the optical path, and when the mirror is in the optical path, the light transmitted through the comparison filter is guided to the solid state detector via the mirror and the light splitting means. An infrared gas analyzer characterized by the following.