Gas analysis device and gas analysis method

Abstract

To provide a gas analysis device and a gas analysis method which analyze a sample gas more accurately than before.SOLUTION: A gas analysis device (1) consists of: a sample cell (11) including a sample gas; a reference cell (12) including a reference gas; a light source (10) for irradiating the sample cell with light (L); and a differential pressure measurement unit (13) for measuring a difference between atmospheric pressures in the sample cell irradiated with the light and the reference cell. A gas analysis method includes measurement of the difference between the atmospheric pressures in the sample cell irradiated with the light and the reference cell.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a gas analysis device and a method for gas analysis. [Background technology]

[0002] Non-Patent Document 1 describes the FT-IR method (Fourier transform infrared spectroscopy), which irradiates a gas with continuous light in the infrared wavelength range and analyzes the components contained in the gas from the interference pattern of the infrared light that has passed through the gas. The FT-IR method is capable of measuring the vibrations of molecules irradiated with infrared light with high resolution, and is also advantageous for identifying chemical substances contained in the gas. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Arkajyoti Banerjee. Fourier Transform Infrared Spectroscopy - A Review” “ResearchGate”, DOI:10.13140 / RG.2.2.16082.89282. 06 August 2021. Summary of the Invention [Problem to be solved by the invention]

[0004] In the FT-IR method described in Non-Patent Document 1, the intensity of light irradiated to the gas is limited, which may reduce the detection sensitivity of a specific component contained in the gas, and thus may reduce the accuracy of the gas analysis. For this reason, the FT-IR method may require a large amount of sample to detect a specific component. [Means for solving the problem]

[0005] In order to solve the above problems, a gas analysis device according to one embodiment of the present disclosure includes a sample cell containing a sample gas, a reference cell containing a reference gas, a light source that irradiates light onto the sample cell, and a differential pressure measuring instrument that measures the difference between the air pressure in the sample cell irradiated with the light and the air pressure in the reference cell.

[0006] Moreover, a gas analysis method according to one aspect of the present disclosure includes irradiating light onto a sample cell containing a sample gas, and measuring the difference between the air pressure in the sample cell irradiated with the light and the air pressure in a reference cell containing a reference gas. Effect of the Invention

[0007] According to one aspect of the present disclosure, analysis of a sample gas can be performed with greater accuracy. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic diagram of a gas analysis device according to a first embodiment of the present disclosure. [Diagram 2] FIG. 1 is a schematic cross-sectional view of a sample cell according to a first embodiment of the present disclosure. [Diagram 3] 11 is a graph showing the measurement results of differential pressure in each example of the present disclosure. [Figure 4] 4 is a graph showing the relationship between light intensity and signal intensity of the gas analyzer according to the first embodiment of the present disclosure. [Diagram 5] FIG. 11 is a schematic diagram of a gas analysis device according to a second embodiment of the present disclosure. [Figure 6] FIG. 11 is a schematic diagram of a gas analysis device according to a third embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] [Embodiment 1] <Outline of gas analyzer> Hereinafter, an embodiment of the present disclosure will be described in detail. In the drawings, the same components are denoted by the same reference numerals and the description thereof will be omitted.

[0010] Fig. 1 is a schematic diagram of a gas analyzer 1 according to this embodiment. Fig. 1 also shows how light is irradiated from a light source 10 (described later) onto a sample cell 11 and a reference cell 12.

[0011] As shown in FIG. 1, the gas analyzer 1 includes a light source 10, a sample cell 11, a reference cell 12, a differential pressure measuring instrument 13, and an analyzing unit 14. The gas analyzer 1 may further include a sample gas source 15 including a sample gas to be analyzed by the gas analyzer 1, a reference gas source 16 including a reference gas, a mirror 17, a half mirror 18, and a beam damper 19. The gas analyzer 1 also includes a control unit CS that controls the operation of each unit of the gas analyzer 1, for example, by a communication means not shown. The operation of each unit of the gas analyzer 1 described later may all be realized by the control of the control unit CS. The control unit CS may include, for example, a pressure measuring instrument that measures the air pressure outside the sample cell 11 and the reference cell 12 to assist the measurement by the differential pressure measuring instrument 13 described later.

[0012] <Light source> The light source 10 emits light L. For example, the light source 10 may include a pulsed laser light source that emits pulsed light as the light L. The light source 10 may also include an infrared light source that emits infrared light as the light L. The infrared light refers to light having a wavelength of, for example, 710 nm or more and 10,000 nm or less. The light source 10 may be, for example, a light source that can change the wavelength of the emitted light, and may be capable of sequentially changing the wavelength, for example, every time the light L is emitted a predetermined number of times. For example, the light source 10 may emit a first light having a first wavelength and a second light having a second wavelength longer than the first wavelength. For example, the light source 10 may be an OPO (Optical Parametric Oscillation) laser. Alternatively, the light source 10 may include a semiconductor laser light source that can sweep the wavelength of the emitted laser light. When the light source 10 is a semiconductor laser light source, the light source 10 can continuously emit the light L, and the wavelength of the light L can be changed more finely. In this specification, "light having a predetermined wavelength" refers to light having the predetermined wavelength as its central emission wavelength; in other words, the light may have wavelength components other than the predetermined wavelength.

[0013] In this embodiment, the sample gas contains a specific component, such as a molecule, that absorbs light L having a specific wavelength and increases its translational energy. Therefore, the air pressure of the sample gas increases when the sample gas is irradiated with light L having a specific wavelength. The sample gas may contain, for example, human breath. The sample gas may also contain a specific component that absorbs light L.

[0014] On the other hand, even when light L is irradiated onto the molecules of the reference gas, the light L is not absorbed regardless of the wavelength of the light L. Alternatively, the light source 10 emits light L having a wavelength included in a wavelength range in which there is no absorption by the reference gas. Therefore, the air pressure of the reference gas is hardly changed by irradiation with light L. For example, the reference gas may contain at least one of a rare gas or nitrogen that does not easily absorb infrared light. For example, the reference gas may contain at least one of a rare gas or nitrogen at 50% or more, preferably 90% or more, and more preferably 99% or more. In addition, the reference gas may not contain the specific component contained in the above-mentioned sample gas. Furthermore, the reference gas may be a gas that contains almost no moisture that easily absorbs infrared light, in other words, a dry gas. In addition, the reference gas may contain the same component as the component that hardly absorbs light L, other than the specific component that absorbs light L contained in the sample gas.

[0015] The mirror 17 and the half mirror 18 may be arranged so that the light L emitted from the light source 10 is irradiated onto each of the sample cell 11 and the reference cell 12 described below. In particular, the half mirror 18 may split the optical path of the light L from the light source 10 so that, of the light L emitted from the light source 10, the light L with approximately half the intensity is irradiated onto the sample cell 11 and the light L with the remaining half the intensity is irradiated onto the reference cell 12. The beam damper 19 may absorb the light L transmitted through each of the sample cell 11 and the reference cell 12 to reduce scattered light.

[0016] <Sample cell> The sample cell 11 has a mechanism capable of introducing a sample gas into the inside. The sample cell 11 will be described in more detail with reference to FIG.

[0017] Fig. 2 is a schematic cross-sectional view of the sample cell 11 according to this embodiment. Fig. 2 particularly shows a cross-section of the sample cell 11 passing through a cavity 22, an optical window 23, an intake path 24, and an air passage 25, which will be described later.

[0018] The sample cell 11 has a housing 21 , a cavity 22 , an optical window 23 , an intake passage 24 , and a ventilation passage 25 .

[0019] The sample cell 11 has a cavity 22 inside a housing 21 made of, for example, stainless steel having high thermal conductivity.

[0020] The housing 21 has optical windows 23 that transmit at least the above-mentioned light L, for example, at one end of the cavity 22 and the other end opposite the one end. Therefore, the sample cell 11 is configured so that the light L irradiated into the cavity 22 from one optical window 23 propagates inside the cavity 22 and is emitted from the other optical window 23. The optical window 23 may contain a material that has a high transmittance of the light L and a low refractive index or dispersion rate for the light L. For example, the optical window 23 may contain calcium fluoride (CaF2), which has a high transmittance in the infrared wavelength range and a low refractive index and low dispersion rate.

[0021] The cavity 22 may have a substantially cylindrical shape with its axial direction aligned with the propagation direction of the light L propagating therein. For example, the dimension D1 of the cavity 22 in the axial direction is 25 mm, and the dimension D2, which is the diameter of the cavity 22 in a direction perpendicular to the axial direction, is 15 mm.

[0022] The cavity 22 communicates with an intake passage 24, which communicates with the sample gas source 15, for example, via a valve (not shown). Therefore, the sample gas SG can be introduced into the cavity 22 from the sample gas source 15 via the intake passage 24. Meanwhile, the cavity 22 communicates with the differential pressure measuring instrument 13 via an air passage 25. In this embodiment, the air pressure in the sample cell 11 refers to the air pressure in the cavity 22 of the sample cell 11. Moreover, irradiating the sample cell 11 with light L refers to irradiating the cavity 22 of the sample cell 11 with light L and propagating the light L into the cavity 22.

[0023] The gas analyzer 1 introduces a sample gas SG into a cavity 22 of a sample cell 11 and transmits light L from a light source 10 to the cavity 22, in other words, the light source 10 irradiates the sample cell 11 containing the sample gas SG with light L. As a result, the light source 10 irradiates the sample gas SG contained in the sample cell 11 with the light L from the light source 10.

[0024] <Reference cell> Returning to FIG. 1, the reference cell 12 has the same configuration as the sample cell 11, except that the intake passage 24 communicates with the reference gas source 16 instead of the sample gas source 15. Thus, the gas analyzer 1 introduces a reference gas into the cavity 22 of the reference cell 12 and transmits light L from the light source 10 to the cavity 22; in other words, the light source 10 irradiates the light L onto the reference cell 12 containing the reference gas. As a result, the light source 10 irradiates the light L from the light source 10 onto the reference gas contained in the reference cell 12.

[0025] The sample gas source 15 and the reference gas source 16 introduce gas into each cell so that the pressure inside the sample cell 11 and the pressure inside the reference cell 12 are substantially the same when light L is not being irradiated. For example, the difference between the pressure inside the sample cell 11 and the pressure inside the reference cell 12 before being irradiated with light L may be 10 Pa or less. This simplifies the content of the analysis by the analysis unit 14 described later.

[0026] <Differential pressure measuring device> The differential pressure measuring instrument 13 measures the difference between the air pressure in the sample cell 11 and the air pressure in the reference cell 12 using the sample gas from the sample cell 11 and the reference gas from the reference cell 12. In particular, the differential pressure measuring instrument 13 according to this embodiment measures the difference between the air pressure in the sample cell 11 and the air pressure in the reference cell 12 while the sample cell 11 and the reference cell 12 are each irradiated with light L. Note that in the present disclosure, the difference between the air pressure in the sample cell 11 and the air pressure in the reference cell 12 may be simply referred to as "differential pressure."

[0027] For example, the differential pressure measuring instrument 13 may include a diaphragm element having a stainless steel thin plate electrode and a copper thin plate electrode in each of a space communicating with the inside of the sample cell 11 and a space communicating with the inside of the reference cell 12. In this case, the differential pressure measuring instrument 13 may measure the differential pressure from a change in electrostatic capacitance between the two electrodes due to bending of the thin plate electrode. Alternatively, the differential pressure measuring instrument 13 may include a thin film having a piezoresistance element between the space communicating with the inside of the sample cell 11 and a space communicating with the inside of the reference cell 12. In this case, the differential pressure measuring instrument 13 may measure the differential pressure from a change in resistance of the piezoresistance element due to bending of the thin film.

[0028] In measuring the difference by the differential pressure measuring instrument 13, the internal space of the differential pressure measuring instrument 13 that communicates with the interior of the sample cell 11 is closed. In measuring the difference by the differential pressure measuring instrument 13, the internal space of the differential pressure measuring instrument 13 that communicates with the interior of the reference cell 12 is closed. In this case, no exchange of substances such as gas occurs between the sample cell 11, the reference cell 12, and the differential pressure measuring instrument 13 and the outside of the gas analyzing apparatus 1. Therefore, the gas analyzing apparatus 1 reduces the influence of the outside of the gas analyzing apparatus 1, and enables the differential pressure measuring instrument 13 to measure minute fluctuations in differential pressure.

[0029] By using a gas that hardly absorbs light L as the reference gas contained in the reference cell 12, the air pressure inside the reference cell 12 may be kept substantially constant while the differential pressure is being measured by the differential pressure measuring instrument 13. This enables the differential pressure measuring instrument 13 to measure a smaller differential pressure. However, this is not limited to the above, and if the change in air pressure inside the reference cell 12 due to irradiation of the reference cell 12 with light L is known, the air pressure inside the reference cell 12 may change slightly. In this case, the differential pressure measuring instrument 13 may take the change in air pressure inside the reference cell 12 into account in the differential pressure to be measured.

[0030] The differential pressure measuring device 13 generates an analog signal having a voltage corresponding to the difference between the measured air pressure in the sample cell 11 and the air pressure in the reference cell 12. The analog signal from the differential pressure measuring device 13 is input to an analyzing unit 14.

[0031] <Analysis Department> The analysis unit 14 may include an AD converter 31 and a calculation unit 32. An analog signal from the differential pressure measuring instrument 13 is input to the AD converter 31. The AD converter 31 converts the analog signal into a digital signal so that calculation can be performed by the calculation unit 32, and inputs the digital signal to the calculation unit 32. The calculation unit 32 includes, for example, a conventionally known computer, and performs calculation based on the digital signal from the AD converter 31. The analysis unit 14 may have a memory that stores data necessary for calculation by the calculation unit 32, a display unit that displays the results of calculation by the calculation unit 32, or the like.

[0032] In particular, the gas analyzer 1 analyzes the difference between the air pressure in the sample cell 11 and the air pressure in the reference cell 12 through calculations performed by the calculation unit 32 of the analysis unit 14 to identify the presence or absence of a specific component in the sample gas SG. For example, the analysis unit 14 identifies the wavelength of the light L irradiated to each of the sample cell 11 and the reference cell 12 at the time when the difference between the air pressure in the sample cell 11 and the air pressure in the reference cell 12 becomes large. In general, the wavelength of light absorbed by a gas containing a specific molecule is uniquely determined. Therefore, the gas analyzer 1 can identify the presence or absence of a specific component contained in the sample gas by identifying the wavelength of the light L described above in the analysis unit 14.

[0033] Here, the differential pressure measuring device 13 may measure the differential pressure when the sample cell 11 and the reference cell 12 are irradiated with a first light having a first wavelength and when the sample cell 11 and the reference cell 12 are irradiated with a second light having a second wavelength. This allows the gas analyzing device 1 to measure the differential pressure when the sample cell 11 is irradiated with light L having different wavelengths, and allows the analyzing unit 14 to perform a more detailed analysis.

[0034] In particular, the light source 10 may irradiate the light L onto each of the sample cell 11 and the reference cell 12 while sweeping the wavelength of the light L. In this way, the differential pressure measuring instrument 13 may measure the differential pressure for a certain range of wavelengths of the light L, and the analyzing unit 14 may identify the wavelength spectrum of the optical absorption of the sample gas SG inside the sample cell 11 from the measurement result.

[0035] In this case, the analysis unit 14 may identify a specific component contained in the sample gas SG by comparing the obtained optical absorption wavelength spectrum of the sample gas SG with the optical absorption wavelength spectrum of a known substance. For example, the analysis unit 14 may compare each peak of the obtained optical absorption wavelength spectrum of the sample gas SG with each peak of the optical absorption wavelength spectrum of a known substance.

[0036] Furthermore, the gas analyzer 1 analyzes the difference between the air pressure in the sample cell 11 and the air pressure in the reference cell 12 through calculations performed by the calculation unit 32 of the analysis unit 14 to identify the concentration of a specific component in the sample gas SG. In general, when light propagates through a gas for a predetermined optical path length, the ratio of the intensity of light absorbed by molecules in the gas is proportional to the concentration of the molecules in the gas. Therefore, the gas analyzer 1 can identify the concentration of a specific component contained in the sample gas by comparing the wavelength of the light L identified above with the magnitude of the difference between the air pressure in the sample cell 11 and the air pressure in the reference cell 12 in the analysis unit 14.

[0037] For example, the analysis unit 14 may determine the ratio of a combination of a plurality of known optical absorption wavelength spectra to obtain the measured optical absorption wavelength spectrum of the sample gas SG. The analysis unit 14 may then determine the ratio of each specific component of the sample gas SG from the ratio of each identified wavelength spectrum, and determine the concentration of the specific component.

[0038] <Effects of gas analyzers> In the gas analysis method using the gas analyzer 1 according to this embodiment, the difference between the air pressure in the sample cell 11 irradiated with light L and the air pressure in the reference cell 12 is measured by the differential pressure measuring device 13. Therefore, in the gas analysis method using the gas analyzer 1, the influence of disturbances such as fluctuations in atmospheric pressure or fluctuations in atmospheric temperature can be reduced while measuring the air pressure fluctuations in the sample cell 11 due to the irradiation of light L, compared to the case of measuring the absolute air pressure in the sample cell 11. Therefore, the gas analysis method using the gas analyzer 1 further improves the accuracy of the analysis of the sample gas SG contained in the sample cell 11.

[0039] For example, when analyzing a sample gas by infrared spectroscopy, the infrared light transmitted through the sample gas is measured, and the intensity of the infrared light from the light source is compared with the intensity of the infrared light transmitted through the sample gas. Here, when the concentration of a specific component in the sample gas is low, the intensity of the infrared light absorbed by the sample gas in infrared spectroscopy is very small. Therefore, taking into account the stability of the intensity of the infrared light source, it is difficult to measure the change in the intensity of the infrared light transmitted through the sample gas in infrared spectroscopy.

[0040] The gas analyzer 1 according to this embodiment measures the difference between the air pressure in the sample cell 11 and the air pressure in the reference cell 12 using the differential pressure measuring device 13, without measuring the intensity of the light L. Therefore, in the analysis of the sample gas SG using the gas analyzer 1, the sample gas SG can be analyzed with higher accuracy even if the intensity of the light L absorbed by the sample gas SG is minute.

[0041] In the gas analysis method using the gas analyzer 1 according to this embodiment, the presence or absence of a specific component contained in the sample gas SG can be identified by analyzing the wavelength of light L at which a difference in pressure occurs between the air pressure in the sample cell 11 and the air pressure in the reference cell 12. In addition, in the above gas analysis method, the concentration of the specific component contained in the sample gas SG can be identified by analyzing the magnitude of the difference in pressure between the air pressure in the sample cell 11 and the air pressure in the reference cell 12 for each wavelength of light L. Therefore, the above gas analysis method can more accurately identify the presence or absence or concentration of a specific component contained in the sample gas SG contained in the sample cell 11.

[0042] In this embodiment, the light L is infrared light, and therefore the gas analyzer 1 can analyze the sample gas SG while reducing the effect of the light L on the composition of the sample gas SG, such as decomposition of specific components in the sample gas SG by the light L. However, the light L may be visible light or ultraviolet light as long as it does not significantly affect the composition of the sample gas SG.

[0043] In this embodiment, the reference cell 12 contains at least one of a rare gas and nitrogen as a reference gas. Since rare gas and nitrogen have low infrared absorption rates, the gas analyzer 1 can measure the change in the air pressure in the sample cell 11 with high accuracy by measuring the difference between the air pressure in the sample cell 11 and the air pressure in the reference cell 12. However, other gases may be used as the reference gas contained in the reference cell 12 as long as they have low reactivity with the light L and the pressure in the reference cell 12 can be made substantially the same as the pressure in the sample cell 11 before the light L is irradiated.

[0044] In this embodiment, the measurement by the differential pressure measuring instrument 13 is performed in a state in which light L is irradiated not only to the sample cell 11 but also to the reference cell 12. As described above, the reference gas may contain a component common to the sample gas SG other than the specific component contained in the sample gas SG. In such a case, the gas analyzing apparatus 1 can perform the analysis of the sample gas SG while reducing the influence of the component.

[0045] <Example> Hereinafter, the gas analyzer 1 according to this embodiment was used to analyze the sample gas SG according to each of Examples 1 and 2. In Example 1, the sample gas SG was a gas in which cyclohexane was diluted with argon to 100 ppm. In Example 2, the sample gas SG was a gas in which acetaldehyde was diluted with argon to 500 ppm. In each of Examples 1 and 2, the reference gas was argon.

[0046] In each of Examples 1 and 2, a sample gas SG was introduced into the sample cell 11, and a reference gas was introduced into the reference cell 12. Next, the sample cell 11 and the reference cell 12 were irradiated with light L from a light source 10, while the difference in air pressure between the sample cell 11 and the reference cell 12 was measured by a differential pressure measuring instrument 13.

[0047] In Example 1, the wave number of light L is 2750 cm -1 From 3150cm -1 Measurement was performed while sweeping the wavelength of the light L from the light source 10 so that the wave number of the light L was 2790 cm. -1From 3150cm -1 Measurements were performed while sweeping the wavelength of the light L from the light source 10 so that: In each of Examples 1 and 2, the light source 10 emitted a pulsed laser beam 10 times per second, for 1 nanosecond each time, as the light L. During the measurements, the light source 10 changed the wavelength of the light L by 0.1 nm every second.

[0048] 3 shows the results of measuring the differential pressure by the differential pressure measuring device 13 in each of Example 1 and Example 2. Graph G1 in FIG. 3 shows the results of measuring in Example 1, and graph G2 in FIG. 3 shows the results of measuring in Example 2. In both graphs in FIG. 3, the horizontal axis represents the wave number of light L (unit: cm -1 ) and the vertical axis represents the differential pressure (unit: Pa).

[0049] As shown in graph G1, in Example 1, the wave number of light L is 2900 cm -1 and 2980 cm -1 This indicates that the air pressure inside the sample cell 11 increased due to the absorption of the light L having that wavenumber by the cyclohexane of the sample gas SG in the sample cell 11.

[0050] As shown in graph G2, in Example 2, the wave number of light L is 3000 cm -1 When the light L having that wavenumber was absorbed by the acetaldehyde in the sample gas SG in the sample cell 11, the pressure difference became large, indicating that the air pressure in the sample cell 11 had increased.

[0051] As is clear from a comparison of the measurement results of Examples 1 and 2, differences in the components of the sample gas SG contained in the sample cell 11 cause differences in the measurement results of the differential pressure by the differential pressure measuring instrument 13. In other words, the gas analyzer 1 can specify the presence and concentration of specific molecules in the sample gas SG by analyzing the measurement results of the differential pressure by the differential pressure measuring instrument 13 by the analysis unit 14.

[0052] <Relationship between light intensity and measurement sensitivity> The relationship between the intensity of light L and the measurement sensitivity of differential pressure by differential pressure measuring instrument 13 will be described with reference to Fig. 4. Fig. 4 is a graph showing the relationship between the intensity of light L and signal intensity in gas analyzer 1 according to this embodiment. In Fig. 4, the horizontal axis represents the intensity of light L (unit: mJ), and the vertical axis represents the signal intensity (arbitrary unit).

[0053] Here, the "signal intensity" in FIG. 4 refers to the intensity of the signal at 2900 cm -1 This refers to the intensity of the signal output by the differential pressure measuring instrument 13 when a sample gas SG containing cyclohexane is analyzed using light L with a fixed wave number around it. The intensity of the signal output by the differential pressure measuring instrument 13 corresponds to the magnitude of the differential pressure. Therefore, in this embodiment, the higher the signal intensity, the higher the measurement sensitivity of the differential pressure measuring instrument 13 becomes, and the more accurately the gas analyzing apparatus 1 can analyze the sample gas SG.

[0054] As shown in Fig. 4, the higher the intensity of light L, the higher the signal intensity, and in particular, the signal intensity is roughly proportional to the intensity of light L. For this reason, in the gas analyzer 1, the higher the intensity of light L from the light source 10, the more accurately the analysis of the sample gas SG can be performed. In particular, since the gas analyzer 1 does not require measurement of the intensity of light L to analyze the sample gas SG, problems such as difficulty in measuring differences in the intensity of light L do not occur even when the intensity of light L is increased. Therefore, the gas analyzer 1 can easily perform more accurate analysis of the sample gas SG by increasing the intensity of light from the light source 10.

[0055] [Embodiment 2] <Omission of light irradiation to the reference cell> 2 is a schematic diagram of a gas analyzer 2 according to this embodiment. The gas analyzer 2 according to this embodiment has a different configuration from the gas analyzer 1 according to the previous embodiment in that light L from a light source 10 is irradiated onto a sample cell 11 but is not irradiated onto a reference cell 12. Therefore, in the gas analyzer 2, it is not necessary to introduce light L into the reference cell 12 and to process light L that has passed through the reference cell 12, so that the number of optical members such as a half mirror 18 and a beam damper 19 can be reduced. Except for the above, the gas analyzer 2 according to this embodiment has the same configuration as the gas analyzer 1 according to the previous embodiment.

[0056] The analysis of the sample gas SG by the gas analysis apparatus 2 of this embodiment is achieved in the same manner as the analysis of the sample gas SG by the gas analysis apparatus 1 of the previous embodiment, except that light L is not irradiated onto the reference cell 12 when measuring the differential pressure by the differential pressure measuring instrument 13.

[0057] For example, as described above, when the reference gas contained in the reference cell 12 hardly absorbs the light L, the air pressure inside the reference cell 12 is kept substantially constant regardless of whether the reference cell 12 is irradiated with the light L or not.

[0058] Therefore, in the analysis of the sample gas SG by the gas analyzer 2, the analysis of the sample gas SG can be performed with sufficient accuracy even when the differential pressure is measured by irradiating the light L only onto the sample cell 11 without irradiating the light L onto the reference cell 12. Therefore, the gas analyzer 2 can analyze the sample gas SG with a simpler configuration.

[0059] [Embodiment 3] <Other examples of sample cell and reference cell arrangement> 3 is a schematic diagram of a gas analyzer 3 according to this embodiment. The gas analyzer 3 according to this embodiment has a different configuration from the gas analyzer 1 described above in that light L from a light source 10 is irradiated onto a sample cell 11, passes through the sample cell 11, and then is irradiated onto a reference cell 12. Therefore, in the gas analyzer 3, it is not necessary to split the light L, and the light L that has passed through the sample cell 11 can be used as the light L to be irradiated onto the reference cell 12, thereby reducing the number of optical members such as a mirror 17, a half mirror 18, and a beam damper 19. Except for the above, the gas analyzer 3 according to this embodiment has the same configuration as the gas analyzer 1 described above.

[0060] The analysis of the sample gas SG by the gas analysis apparatus 3 of this embodiment is achieved in the same manner as the analysis of the sample gas SG by the previously described gas analysis apparatus 1, except that when the differential pressure is measured by the differential pressure measuring instrument 13, light L transmitted through the sample cell 11 is irradiated onto the reference cell 12.

[0061] The differential pressure measurement by the differential pressure measuring instrument 13 of the gas analyzing device 3 according to this embodiment is performed while irradiating both the sample cell 11 and the reference cell 12 with light L. Furthermore, since the intensity of the light L decreases little while passing through the sample cell 11, even when the differential pressure is measured by irradiating the reference cell 12 with light L that has passed through the sample cell 11, the measured differential pressure value is unlikely to be significantly affected.

[0062] Therefore, in the analysis of the sample gas SG by the gas analyzer 3, the differential pressure can be measured by irradiating light L to both the sample cell 11 and the reference cell 12 with a simpler configuration. Therefore, the gas analyzer 2 achieves both a simplified configuration and improved accuracy in the analysis of the sample gas SG.

[0063] <Summary> A gas analysis apparatus according to a first aspect of the present disclosure includes a sample cell containing a sample gas, a reference cell containing a reference gas, a light source that irradiates light onto the sample cell, and a differential pressure measuring instrument that measures the difference between the air pressure in the sample cell irradiated with the light and the air pressure in the reference cell.

[0064] The gas analyzer according to a second aspect of the present disclosure is the above-mentioned first aspect, further comprising an analysis unit that analyzes the difference to identify the presence or absence of a specific component in the sample gas.

[0065] A gas analyzer according to a third aspect of the present disclosure is the above-mentioned second aspect, wherein the analysis unit analyzes the difference to determine the concentration of a specific component in the sample gas.

[0066] A fourth aspect of the present disclosure relates to the gas analyzer of any one of the first to third aspects, wherein the light source includes an infrared light source.

[0067] A gas analyzer according to a fifth aspect of the present disclosure is any one of the first to fourth aspects, wherein the light source includes at least one of a pulsed laser light source and a semiconductor laser light source.

[0068] A sixth aspect of the present disclosure relates to the gas analyzer of any one of the first to fifth aspects, wherein the reference gas includes at least one of a rare gas and nitrogen.

[0069] A gas analysis device according to a seventh aspect of the present disclosure is any one of the first to sixth aspects above, in which the light source irradiates the reference cell with light, and the differential pressure measuring instrument measures the difference between the air pressure in the sample cell irradiated with the light and the air pressure in the reference cell irradiated with the light.

[0070] A gas analysis device according to an eighth aspect of the present disclosure is any one of the first to seventh aspects above, wherein the light source emits a first light having a first wavelength and a second light having a second wavelength longer than the first wavelength, and the differential pressure measuring instrument measures the difference when the light source irradiates the first light onto the sample cell and when the light source irradiates the second light onto the sample cell.

[0071] A ninth aspect of the present disclosure relates to the gas analyzer of any one of the first to eighth aspects, wherein the difference between the air pressure in the sample cell and the air pressure in the reference cell before the light is irradiated is 10 Pa or less.

[0072] A gas analysis device according to aspect 10 of the present disclosure is any one of aspects 1 to 9 above, wherein, in measuring the difference by the differential pressure measuring instrument, the internal space of the differential pressure measuring instrument that communicates with the interior of the sample cell is closed, and the internal space of the differential pressure measuring instrument that communicates with the interior of the reference cell is closed.

[0073] A gas analysis method according to an eleventh aspect of the present disclosure includes irradiating light onto a sample cell containing a sample gas, and measuring the difference between the air pressure in the sample cell irradiated with the light and the air pressure in a reference cell containing a reference gas.

[0074] A gas analysis method according to a twelfth aspect of the present disclosure is the above-mentioned eleventh aspect, which includes determining the presence or absence of a specific component in the sample gas by analyzing the measured difference.

[0075] A thirteenth aspect of the present disclosure relates to a gas analysis method according to the twelfth aspect above, wherein determining the presence or absence of the specific component in the sample gas includes determining a concentration of the specific component in the sample gas.

[0076] The present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present disclosure. [Explanation of symbols]

[0077] 1 Gas analyzer 10 light source 11 Sample cell 12 Reference Cell 13 Differential pressure measuring instrument 14 Analysis Department

Claims

1. a sample cell containing a sample gas; a reference cell containing a reference gas; A light source that irradiates the sample cell with light; a differential pressure measuring device that measures the difference between the air pressure in the sample cell irradiated with the light and the air pressure in the reference cell.

2. 2. The gas analyzer according to claim 1, further comprising an analysis unit that analyzes the difference to identify the presence or absence of a specific component in the sample gas.

3. The gas analyzer according to claim 2 , wherein the analysis section analyzes the difference to identify the concentration of a specific component in the sample gas.

4. 4. A gas analyzer according to claim 1, wherein the light source includes an infrared light source.

5. 4. The gas analyzer according to claim 1, wherein the light source includes at least one of a pulsed laser light source and a semiconductor laser light source.

6. 4. The gas analyzer according to claim 1, wherein the reference gas includes at least one of a rare gas and nitrogen.

7. the light source irradiates the reference cell with the light; 4. The gas analyzer according to claim 1, wherein the differential pressure measuring device measures a difference between the air pressure in the sample cell irradiated with the light and the air pressure in the reference cell irradiated with the light.

8. the light source emits a first light having a first wavelength and a second light having a second wavelength longer than the first wavelength; 4. The gas analysis apparatus according to claim 1, wherein the differential pressure measuring instrument measures the difference when the light source irradiates the sample cell with the first light and when the light source irradiates the sample cell with the second light.

9. 4. The gas analyzer according to claim 1, wherein a difference between an air pressure in the sample cell and an air pressure in the reference cell before the light is irradiated is 10 Pa or less.

10. 4. The gas analysis apparatus according to claim 1, wherein, in measuring the difference by the differential pressure measuring instrument, an internal space of the differential pressure measuring instrument that communicates with an internal space of the sample cell is closed, and an internal space of the differential pressure measuring instrument that communicates with an internal space of the reference cell is closed.

11. Irradiating a sample cell containing a sample gas with light; measuring the difference between the air pressure in the sample cell illuminated with the light and the air pressure in a reference cell containing a reference gas.

12. 12. A method for gas analysis according to claim 11, comprising identifying the presence or absence of a particular component in the sample gas by analysis of the measured difference.

13. 13. The gas analysis method according to claim 12, wherein determining the presence or absence of the specific component in the sample gas includes determining a concentration of the specific component in the sample gas.

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