Gas correlation filter wheel and gas analyzer

Abstract

To provide a gas correlation filter wheel that can stably measure multiple gas components contained in a sample gas. [Solution] A gas correlation filter wheel according to one aspect of the present disclosure is a gas correlation filter wheel used in a gas correlation type gas analyzer, comprising a plurality of gas filters and a wheel capable of concentrically housing the plurality of gas filters, each of the gas filters having a cylindrical housing, light transmission windows sealing each end of the housing, and an optical filter on one of the light transmission windows, and the plurality of gas filters having at least a first gas correlation filter set having a first optical filter capable of selectively transmitting the absorption wavelength of a first target gas as the optical filter, and a second gas correlation filter set having a second optical filter capable of selectively transmitting the absorption wavelength of a second target gas as the optical filter.

Description

Technical Field

[0001] The present disclosure relates to a gas correlation filter wheel and a gas analyzer.

Background Art

[0002] A gas analyzer using the gas filter correlation method measures the concentration of a gas to be measured by applying a light beam of a specific wavelength absorbed by the gas to be measured and measuring the attenuation amount (amplitude ratio of the detection waveform) from the received light signal. It is known that the absorption intensity of a gas follows Lambert-Beer's law, and the ratio of the light quantity has a correlation with the gas concentration.

[0003] The gas filter correlation method (GFC) is known as a measurement method that is not affected by interfering gases or optical noise excluding electrical noise by alternately detecting a high-concentration gas to be measured and a reference gas (zero gas) and taking the difference.

[0004] In Patent Document 1, the gas filter cell portion for a single component of a gas analyzer using the gas filter correlation method is disclosed.

[0005] In Patent Document 1, a method of directly enclosing a gas in a rotating gas cell structure to form a gas cell is disclosed. In the case of a single-component meter, even when applying the gas filter correlation method, two types of gases, namely the gas to be measured and the reference gas, may be enclosed, so there are two sealing ports.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, the technology disclosed in Patent Document 1 measures a single gas component. In order to realize a multi-component analyzer in the gas analyzer described in Patent Document 1, it is necessary to seal two types of gas for each type of gas to be measured: the gas to be measured and a reference gas, which greatly restricts space. In addition, the structure becomes complicated, and there is a risk that if even one type of gas fails to be sealed, the wheel itself will need to be remade.

[0008] One aspect of this disclosure aims to provide a gas correlation filter wheel capable of stably measuring multiple gas components contained in a sample gas. [Means for solving the problem]

[0009] In one aspect of this disclosure, a gas correlation filter wheel used in a gas correlation type gas analyzer, Multiple gas filters, A wheel capable of housing the plurality of gas filters in a concentric circle is provided, Each of the gas filters comprises a cylindrical housing, light-transmitting windows sealing each end of the housing, and an optical filter on one of the light-transmitting windows. The aforementioned multiple gas filters are A first gas correlation filter set comprising a gas filter for a first target gas containing a first target gas, and a gas filter containing a reference gas that does not absorb infrared light, wherein the first gas correlation filter set comprises a first optical filter capable of selectively transmitting the absorption wavelength of the first target gas, and A second gas correlation filter set comprising a gas filter for a second target gas containing a second target gas, and a gas filter containing a reference gas that does not absorb infrared light, wherein the second gas correlation filter set comprises at least one optical filter capable of selectively transmitting the absorption wavelength of the second target gas, We provide gas correlation filter wheels. [Effects of the Invention]

[0010] According to one aspect of this disclosure, a gas correlation filter wheel capable of stably measuring multiple gas components contained in a sample gas can be provided. [Brief explanation of the drawing]

[0011] [Figure 1] This is a configuration diagram showing an example of the gas analyzer according to this embodiment. [Figure 2] This is a configuration diagram showing an example of a wheel in the gas correlation filter wheel of this embodiment. [Figure 3] This is a diagram showing an example of a gas correlation filter wheel according to this embodiment. [Figure 4] Figure 3 is a cross-sectional view showing the IV-IV' section of the gas correlation filter wheel. [Figure 5] This figure shows an example of a gas correlation filter combination in the gas correlation filter wheel of this embodiment. [Modes for carrying out the invention]

[0012] The gas correlation filter wheel and gas analyzer according to the present invention will be described in detail below with reference to the attached drawings. In each drawing, the same components are denoted by the same reference numerals, and redundant explanations may be omitted.

[0013] Gas filter correlation (GFC) gas analyzers detect infrared light of a specific wavelength absorbed by the target gas by transmitting it through the analyzer. The concentration of the target gas is measured by measuring the amplitude ratio of the detected infrared light waveform as the infrared light attenuation. Gas filter correlation analyzers use a gas correlation filter wheel that houses and rotates a gas filter containing a high-purity target gas and a gas filter containing a reference gas that does not absorb infrared light, alternately transmitting infrared light through each gas filter. Therefore, they are less susceptible to optical noise such as fluctuations in the intensity of transmitted infrared light and interference from moisture in the sample gas and gases other than the target gas.

[0014] In the gas analyzer described above, a pair of gas filters are included, one containing a high-purity target gas and the other containing a reference gas that does not absorb infrared light. When measuring the concentration of the target gas using a combination of an infrared light source that emits light across a broad wavelength range and a photodetector sensitive to a broad wavelength range, the change in the amount of light absorbed by the target gas becomes extremely small.

[0015] When measuring the concentration of a single target gas, the signal-to-noise ratio (S / N ratio) can be ensured by optimizing the emission and reception wavelength bands of the light source. However, when measuring the concentrations of multiple target gases, the emission and reception wavelength bands of the light source are broadband, which leads to a problem where the signal change due to the absorption of the target gas becomes relatively small, making measurement impossible.

[0016] According to the gas correlation filter wheel of this embodiment, there are multiple gas correlation filter sets corresponding to multiple target gases, and each gas filter in each gas correlation filter set has an optical filter that can selectively transmit the absorption wavelength of a specific target gas. This makes it easier to capture signal changes input to the light receiving unit in gas correlation analysis and improves sensitivity. Therefore, multiple gas components contained in the sample gas can be measured stably.

[0017] FIG. 1 is a configuration diagram showing an example of the gas analyzer of the present embodiment including the gas correlation filter wheel of the present embodiment.

[0018] As shown in FIG. 1, the gas analyzer 1 of the present embodiment detects the concentration or presence / absence of the gas to be measured in the sample gas G in the sample gas cell 40. Specifically, the gas analyzer 1 can measure the concentration of each of a plurality of gases to be measured contained in the sample gas G to be analyzed. Further, the gas analyzer 1 can detect that there is no gas to be measured if the gas concentration is zero or below a predetermined value, and can also detect the presence / absence of the gas to be measured.

[0019] The gas analyzer 1 of the present embodiment includes a light source 10, a gas correlation filter wheel 20, a rotating means 30, a sample gas cell 40, and a light receiving unit 50. The gas analyzer 1 may further include a signal processing unit 60 connected to the light receiving unit 50. In FIG. 1, the arrow in the sample gas cell 40 indicates the path of the sample gas G, the dashed arrow indicates the path of the light beam L, and the arrow from the light receiving unit 50 to the signal processing unit 60 indicates the path of the electrical signal.

[0020] The light source 10 is a light source that emits infrared rays. The light source 10 may use a heat source light source such as a silicon nitride heater having a black body temperature of about 1000°C. In order to make the emitted infrared rays into infrared rays close to parallel light, optical components such as a lens or a parabolic mirror (not shown) may be provided. Further, an aperture may be provided to limit the half-value angle of the light source 10.

[0021] The gas correlation filter wheel 20 will be described in detail with reference to FIGS. 2 to 4.

[0022] [[ID=Z]] FIG. 2 is a configuration diagram showing an example of the wheel in the gas correlation filter wheel 20 of the present embodiment. FIG. 3 is a configuration diagram showing an example of the gas correlation filter wheel 20 of the present embodiment. FIG. 4 is a cross-sectional view showing the IV-IV' cross-section of the gas correlation filter wheel 20 of FIG.

[0023] The gas correlation filter wheel 20 has a wheel 21 and a plurality of gas filters (22, 23) housed in the wheel 21. As shown in Figure 2, the wheel 21 has a circular shape when viewed from above. The wheel 21 has a plurality of slits 21a arranged concentrically around the wheel 21 for housing the plurality of gas filters (22, 23), and has a rotating bearing 21b at the center of the wheel 21 to allow rotation.

[0024] As shown in Figures 2 to 4, the gas correlation filter wheel 20 can house multiple gas filters (22, 23) in multiple slits 21a in the wheel 21.

[0025] Regarding each gas filter of the gas correlation filter wheel 20, the gas filter 22 for the gas to be measured will be described as a representative example, but the gas filter 23 for the reference gas can have a similar configuration, except that the enclosed gas is different. As shown in Figures 3 to 4, each gas filter has a gas filter housing 221, a pair of light-transmitting windows 222 (222a, 222b) that seal each end of the housing 221, and an optical filter 223 on the light-incident light-transmitting window 222a. Each gas filter may further have, if necessary, an adhesive 224 for bonding the light-transmitting windows 222 to the housing 221, an introduction hole 225 on the side of the housing 221 through which gas G1 can be introduced, and a pipe 226 that can be crimped or adhesively sealed to the introduction hole 225. Each gas filter can be manufactured independently for each type of gas.

[0026] The gas filter housing 221 is not particularly limited as long as it is cylindrical, but it is preferably cylindrical or polygonal in shape. Each end of the housing 221 has a surface (adhesive area) for positioning the light-transmitting window 222. The light-transmitting window 222 can be attached to each end of the housing 221 with a suitable adhesive (e.g., epoxy adhesive), and the assembly can be carried out in such a way that gas does not leak from the connection points.

[0027] In one embodiment, it is preferable that each gas filter has an introduction hole 225 on the side of the housing 221 through which gas can be introduced and sealed, and a pipe 226 that is inserted into the introduction hole 225 and can be crimped or adhesively sealed. The pipe 226 can be attached to the introduction hole 225 with a suitable adhesive (e.g., epoxy adhesive), and assembled so that gas does not leak from the connection part. Furthermore, because the pipe 226 can be crimped or adhesively sealed, the pipe 226 can be crimped or bonded by a suitable method such as fusion bonding after gas is sealed, and thus the gas can be sealed.

[0028] The light transmission window 222 transmits light in the wavelength band that includes the absorption wavelength of the gas being measured. In the infrared region, for example, calcium fluoride (CaF2), quartz (SiO2), germanium, etc., can be used.

[0029] In this embodiment, the gas correlation filter wheel has multiple combinations of gas filters 22 for the gas to be measured and gas filters 23 for the reference gas, thereby enabling gas analysis of multiple components. For each gas component to be measured, the gas correlation filter consists of a total of two gas filters: one containing the gas to be measured and another containing the reference gas. In the gas correlation filter combination, an optical filter capable of selectively transmitting the absorption wavelength of the gas to be measured is installed.

[0030] Specifically, in the case of a gas correlation filter wheel capable of analyzing two or more gas components, it shall have at least the first gas correlation filter set described in (A) below and the second gas correlation filter set described in (B) below. (A) A first gas correlation filter set having a gas filter 22A for a first target gas to be measured and a gas filter 23A for a reference gas, wherein the first gas correlation filter set has a first optical filter (223A, 233A) that is capable of selectively transmitting the absorption wavelength of the first target gas to be measured. (B) A second gas correlation filter set having a gas filter 22B for a second target gas and a gas filter 23B for a reference gas, wherein the second gas correlation filter set has a second optical filter (223B, 233B) as an optical filter that is capable of selectively transmitting the absorption wavelength of the second target gas.

[0031] Furthermore, as shown in Figure 5, in the case of a gas correlation filter wheel capable of analyzing three gas components, it has the first gas correlation filter set (A) above, the second gas correlation filter set (B) above, and the third gas correlation filter set (C) below. (C) A third gas correlation filter set having a gas filter 22C for a third target gas and a gas filter 23C for a reference gas, wherein the third gas correlation filter set has a third optical filter (223C, 233C) as an optical filter that is capable of selectively transmitting the absorption wavelength of the third target gas.

[0032] The gas to be measured can be appropriately selected depending on the purpose, and examples include carbon monoxide, carbon dioxide, methane, propane, ammonia, and nitrous oxide. The gas correlation filter wheel and gas analyzer of this embodiment allow for the easy measurement of multiple types of gases.

[0033] As a reference gas, an inert gas that does not absorb in the infrared absorption region including the absorption wavelength of the gas being measured can be used, such as nitrogen (N2) or argon (Ar). In a set of multiple gas correlation filters, the reference gases in each gas filter for the reference gas may be the same or different from each other.

[0034] The optical filter is not particularly limited as long as it is capable of selectively transmitting the absorption wavelength of the gas to be measured, and can be appropriately selected according to the purpose. Examples include bandpass filters, cutoff filters, and cut-on filters. These may be used individually or in combination of two or more. Among these, bandpass filters are preferred. The optical filter is provided to narrow the wavelength of infrared radiation detected by the light receiving unit 50 in order to reduce the influence of interference from components other than the gas to be measured. The optical filter may be provided on the light source 10 side of each gas filter, or on the opposite side from the light source 10.

[0035] Optical filters are attached to each gas being measured. More specifically, in the gas analyzer 1 according to this embodiment, an optical filter 223A that transmits infrared light of the wavelength component absorbed by the gas being measured sealed in gas filter 22A is attached to the gas filter 22A for the gas being measured and the gas filter 23A for the reference. Then, an optical filter 223B that transmits infrared light of the wavelength component absorbed by the gas being measured sealed in gas filter 22B is attached to the gas filter 22B for the gas being measured and the gas filter 23B for the reference. Furthermore, an optical filter 223C that transmits infrared light of the wavelength component absorbed by the gas being measured sealed in gas filter 22C is attached to the gas filter 22C for the gas being measured and the gas filter 23C for the reference.

[0036] When measuring multiple target gases, the emission and reception wavelength bands of the light source are broadband, which can lead to a problem where the signal change range due to the absorption of the target gases becomes relatively small and measurement becomes impossible. However, by applying optical filters that selectively transmit the absorption wavelength of specific target gases, it is possible to prevent light in unwanted wavelength ranges from entering, making it easier to capture signal changes (improving sensitivity). Therefore, according to the gas correlation filter wheel 20 of this embodiment, there are multiple gas correlation filter sets corresponding to multiple target gases, and each gas filter in each gas correlation filter set has an optical filter that selectively transmits the absorption wavelength of a specific target gas. This makes it easier to capture signal changes input to the light receiving unit in gas correlation analysis, improving sensitivity. Consequently, multiple gas components contained in the sample gas can be measured stably.

[0037] The type of gas to be analyzed can be appropriately selected according to the purpose, and the desired gas correlation filter wheel 20 can be manufactured by appropriately adjusting the size of the wheel 21 of the corresponding gas correlation filter wheel 20, the number and arrangement of multiple gas filters (22, 23), etc.

[0038] Depending on the type and number of gases to be measured, multiple gas filters having a desired gas correlation filter set are manufactured and placed in each slit 21a of the wheel 21. The method of storing each gas filter (22, 23) in each slit 21a of the gas correlation filter wheel 20 is not particularly limited, but for example, it can be stored using fixing O-rings 26, a storage wheel cover, and fasteners such as screws. Specifically, O-rings 26 are placed at the bottom of each slit 21a of the wheel 21, and each gas filter is placed in each slit 21a. At this time, the optical filter may be integrated with the gas filter, or the optical filter 223 may be placed on the light transmission window 222a on the light incident side when storing the gas filter, and both are suitably applicable. By holding each gas filter between the upper and lower O-rings 26 which function as spring material, micro-movement of each gas filter in the gas correlation filter wheel 20 can be prevented. As a result, even when the gas correlation filter wheel 20 rotates at high speed, accurate analysis of multiple types of gases can be performed.

[0039] The rotating means 30 includes a rotating shaft attached to the rotating bearing 21b of the wheel 21, and a motor that rotates the rotating shaft. The rotating means 30 rotates the gas correlation filter wheel 20 at any rotational speed. The gas correlation filter wheel 20 is arranged so that the light rays L irradiated by the light source 10 pass through a pair of light-transmitting windows (e.g., 222a, 222b) of each gas filter, and as the gas correlation filter wheel 20 rotates, each gas filter is sequentially inserted into the optical path of the light rays L irradiated by the light source 10.

[0040] From the viewpoint of suppressing inverter noise, it is preferable to use, for example, an AC (Alternating Current) motor for the rotating means 30, and even more preferable to use an AC synchronous motor. However, the rotating means 30 is not limited to these motors, and any general-purpose motor can be used. In this embodiment, the motor constituting the rotating means 30 can rotate the gas filter wheel 20 at, for example, 1500 rpm.

[0041] To detect the position and type of gas filter, for example, position detection units may be provided at positions corresponding to each gas filter around the gas correlation filter wheel 20, and an optical sensor that receives infrared light from the position detection unit may be provided at a position opposite to the position detection unit. Each position detection unit detects the position of each gas filter in synchronization with the rotation of the gas correlation filter wheel 20. When the gas correlation filter wheel 20 is rotated by the rotating means 30, each position detection unit is detected by the optical sensor and transmits a signal synchronized with the position of each gas filter to the optical sensor.

[0042] The method for detecting the position of the gas filter by the position detection unit is not limited to this, and various methods can be employed to generate position information corresponding to the position of the gas filter as an electrical signal. For example, instead of an optical sensor, a magnetic detection element such as a Hall element may be used to transmit a signal based on the magnetism emitted from the position detection unit. In this case, each position detection unit is formed by a magnet that emits a different magnetism for each gas filter. The signals obtained by the optical sensor or magnetic detection element are input to the signal processing unit 60 as synchronization signals and can be integrated with the input signal of the light receiving unit 50.

[0043] The sample gas cell 40 includes a sample gas introduction section 41 into which the sample gas G is introduced, a sample gas outlet section 42 from which the sample gas G is discharged, a main body of the sample gas cell through which the introduced sample gas G can flow, and reflective mirrors 43a to 43e. The sample gas introduction section 41 and the sample gas outlet section 42 may be connected to a pipe through which the sample gas G flows, or to the environment to be measured, so that the sample gas G flows through the sample gas cell 40. Alternatively, the sample gas G may be filled into the sample gas cell 40 and the concentration of the target gas or the presence or absence of the target gas may be detected in a batch manner. In any case, the system can be suitably applied.

[0044] The sample gas cell 40 communicates with the gas introduction section 41 and has a cylindrical shape into which the sample gas G is introduced. The interior of the sample gas cell 40 (measurement space) may be a closed space partitioned by, for example, the inner wall of the cylindrical part of the sample gas cell 40 and the inner wall sealing the end of the cylindrical part, or it may be a closed space partitioned by the inner wall of the cylindrical part of the sample gas cell 40, the light transmission window of the gas correlation filter wheel 20, the light transmission window of the light receiving section 50, and the inner wall of the reflective mirror 43. The inner wall of the sample gas cell 40 can be, for example, made of polished stainless steel. This allows the gas analyzer 1 to suppress the adsorption of particulate matter (PM) and the like contained in the sample gas G. The gas outlet section 42 communicates with the sample gas cell 40 and discharges the sample gas G from the interior of the sample gas cell 40.

[0045] As shown in Figure 1, the light ray L irradiated by the light source 10 passes through a pair of light transmission windows of a gas filter 22 placed in its optical path, then passes through the sample gas cell 40, and is received by the light receiving unit 50. Specifically, the light ray L that has passed through the pair of light transmission windows of the gas filter 22 is multiple-reflected by a group of reflective mirrors 43a to 43e in the sample gas cell 40 and passes through the sample gas G in the sample gas cell 40. When the light ray L passes through the sample gas G in the sample gas cell 40, it is absorbed by the target gas contained in the sample gas G. The remaining light that is not absorbed, i.e., the transmitted light, is then incident on the light receiving unit 50, and its light intensity is detected. Since the intensity of the light reaching the light receiving unit 50 changes according to the gas concentration of the target gas contained in the sample gas G, the concentration of the target gas can be calculated from the light intensity detected by the light receiving unit 50.

[0046] The sample gas cell 40 is equipped with reflective mirrors 43a to 43e to perform multiple reflections of the incident infrared light. The infrared light incident on the sample gas cell 40 is reflected by the reflective mirrors 43a, 43b, 43c, 43d, and 43e in that order and received by the light receiving unit 50. The reflective mirrors 43 may have only some surfaces that are reflective, or all surfaces that are reflective.

[0047] The reflective mirrors 43a to 43e allow for multiple reflections of the incident light ray L. This increases the optical path length of the infrared light incident on the sample gas cell 40, enabling accurate concentration measurement even when the target component in the sample gas is present in trace amounts.

[0048] The reflective mirror 43 has high reflectivity at the central wavelength λ and bandwidth (FWHM) of the light ray L irradiated by the light source 10, and reflects the laser light in approximately parallel directions. Instead of the reflective mirror, reflective optical components such as a prism or corner cube that performs multiple right-angle reflections, a mirror assembly constructed by setting the angle between two mirrors at a right angle, or a glass sphere with a reflective surface deposited on a hemispherical base may be used.

[0049] The light receiving unit 50 receives the light ray L after it has been irradiated by the light source 10 and passed through the sample gas G, and outputs a detection signal corresponding to the received light. The light receiving unit 50 may be positioned opposite the light source 10 as shown in Figure 1, or in another embodiment, it may be positioned alongside the light source 10.

[0050] The light-receiving unit 50 is equipped with a light-receiving element. The light-receiving element can be a PbSe element which has high sensitivity in the mid-infrared region, but is not limited to this, and various elements which have sensitivity in the mid-infrared region can be used.

[0051] The infrared light that passes through the gas filters (22, 23) and the sample gas cell 40 and is received by the light-receiving element of the light-receiving unit 50 is converted into an electrical signal and input to the signal processing unit 60. The light-receiving unit 50 may also be equipped with a temperature detection element such as a thermistor and a Peltier element as a cooling means.

[0052] The signal processing unit 60 calculates the concentration of the target gas based on the electrical signal input from the light receiving unit 50. The signal processing unit 60 can measure the concentration of the target gas by acquiring the change in the intensity of infrared light at the absorption wavelength of the target gas.

[0053] This explanation will use the example of measuring the concentrations and / or presence of multiple target gases: CO2, CO, and CH4.

[0054] To detect CO2, CO, and CH4 respectively, an optical filter capable of selectively transmitting a wavelength range of approximately 100 nm centered around 4260 nm can be used as the absorption wavelength for CO2; an optical filter capable of selectively transmitting a wavelength range of approximately 100 nm centered around 4670 nm can be used as the absorption wavelength for CO; and an optical filter capable of selectively transmitting a wavelength range of approximately 100 nm centered around 3110 nm can be used as the absorption wavelength for CH4. A light source emitting infrared light including these absorption wavelengths can be used as the light source.

[0055] Each optical filter is introduced into each gas correlation filter set of the gas correlation filter wheel in this embodiment. As the motor rotates, the emitted light from both the gas filter containing the reference gas and the gas filter containing the gas to be measured is used.

[0056] Light rays that have passed through the gas correlation filter wheel are introduced into the sample gas cell. A multiple reflection cell can also be used here to ensure sensitivity.

[0057] As the photodetector, any photodetector that is sensitive to infrared light at wavelengths around 4260 nm, 4670 nm, and 3110 nm can be used. For example, a PbSe element can be considered.

[0058] In the gas filter correlation method, light transmitted through a cell containing a reference gas is absorbed more by the sample gas in the sample gas cell. On the other hand, light transmitted through a cell containing the target gas reaches the sample gas cell after much of the target gas has already been absorbed by that cell, resulting in a decrease in absorbance in the sample gas cell.

[0059] By comparing and calculating the light from both sources, it is possible to remove common noise from both sources and calculate the gas concentration.

[0060] More specifically, the difference between the peak and bottom values ​​of the signal of the reference gas is V N2 The difference between the peak and bottom values ​​of the signal of the gas being measured is V Target Assuming that Target Gas Concentration is the gas concentration indicator value, the following relationship (1) is satisfied. The signal processing unit 60 calculates the gas concentration indicator value using equation (1).

[0061]

number

[0062] The gas analyzer 1 of this disclosure is suitable for use in facilities where zero detection of multiple gas components is required for toxic gases such as carbon dioxide, carbon monoxide, and methane. In addition, it is also useful as an analytical instrument for use in confined spaces such as ships, for measuring combustion exhaust gases from boilers and waste incineration, gas analysis for steelmaking (blast furnaces, converters, heat treatment furnaces, sintering (pellet equipment), coke ovens), gas analysis in fruit and vegetable storage and ripening, gas analysis in the biochemistry field (microorganisms, fermentation), measurement of air pollutant gases (incinerators, flue gas desulfurization / denitrification), measurement of exhaust gases from internal combustion engines (exhaust gas tester), gas analysis for disaster prevention (explosive gas detection, toxic gas detection, combustion gas analysis of new building materials), gas analysis for plant cultivation, chemical analysis (petroleum refining plants, petrochemical plants, gas generation plants), measurement of environmental gases (ground concentration, tunnel concentration, parking lot, building management), and various physical and chemical experiments.

[0063] As described above, embodiments have been explained, but these embodiments are presented as examples only, and the present invention is not limited by these embodiments. The above embodiments can be implemented in various other forms, and various combinations, omissions, substitutions, and modifications are possible without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of Symbols]

[0064] 1. Gas analyzer 10 light source 20 Gas correlation filter wheel 21 wheels 22 Gas filters for the gas to be measured 223 Optical Filters 23 Gas filters for comparative reference gases 233 Optical Filters 26 O-rings 30 Rotating means 40 Sample gas cells 41 Sample gas introduction section 42 Sample gas outlet 43 Multiple reflection section 50 Light receiving part 60 Signal Processing Unit G Sample gas L-ray

Claims

1. A gas correlation filter wheel used in a gas correlation type gas analyzer, Multiple gas filters, A wheel capable of housing the plurality of gas filters in a concentric circle is provided, Each of the gas filters comprises a cylindrical housing, light-transmitting windows sealing each end of the housing, and an optical filter on one of the light-transmitting windows. The aforementioned multiple gas filters are A first gas correlation filter set comprising a gas filter for a first target gas containing a first target gas, and a gas filter containing a reference gas that does not absorb infrared light, wherein the first gas correlation filter set comprises a first optical filter capable of selectively transmitting the absorption wavelength of the first target gas, and A second gas correlation filter set comprising a gas filter for a second target gas containing a second target gas, and a gas filter containing a reference gas that does not absorb infrared light, wherein the second gas correlation filter set comprises at least one optical filter capable of selectively transmitting the absorption wavelength of the second target gas, Gas correlation filter wheel.

2. The gas correlation filter wheel according to claim 1, further comprising an introduction hole on the side of the housing through which gas can be introduced, and a pipe that can be crimped or adhesively sealed to the introduction hole.

3. A gas analyzer for measuring the concentration of a target gas contained in a sample gas, A light source that emits infrared light, A gas correlation filter wheel according to claim 1 or 2, The infrared light that has passed through one gas filter in the gas correlation filter wheel is incident on a sample gas cell through which the sample gas containing the gas to be measured flows, Equipped with, Gas analyzer.

4. A light receiving unit that receives the infrared light transmitted through the sample gas cell and converts it into a light receiving signal which is an electrical signal, The system further includes a signal processing unit that calculates the concentration of the target gas contained in the sample gas based on the received light signal, The gas analyzer according to claim 3.

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