Gas detection device and gas detection method

Abstract

To provide a gas detection device and a gas detection method that enable appropriate detection of gas discharged to space.SOLUTION: The gas detection device pertaining to an embodiment comprises: a first irradiation unit that can irradiate gas discharged to space with first light having a first wavelength; a second irradiation unit that can irradiate the gas with second light having a second wavelength shorter than the first wavelength; an irradiation position adjustment unit that can control a position irradiated with first light, of the gas; a gas analysis unit that can analyze a component of the gas on the basis of first light having passed through the gas; and a gas visualization unit that visualizes the concentration distribution of the gas on the basis of second light having passed through the gas. The irradiation position adjustment unit controls the position irradiated with first light, of the gas on the basis of the visualized concentration distribution of the gas.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] FIELD Embodiments of the present invention relate to a gas detection device and a gas detection method. [Background technology]

[0002] Molecules have a specific absorption spectrum for infrared rays, so by irradiating a target space with infrared rays, it is possible to detect gases released into the space and analyze the components of the gases released into the space. However, the concentration (density) of the gas released into the space varies, and therefore, depending on the position of the infrared light irradiated on the gas released into the space, the detection sensitivity and analytical accuracy may decrease. Therefore, there has been a demand for the development of a technology that can appropriately detect gas released into space. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-062176 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a gas detection device and a gas detection method that can appropriately detect gas released into a space. [Means for solving the problem]

[0005] A gas detection device according to an embodiment includes a first irradiation unit capable of irradiating a gas released into a space with first light having a first wavelength, a second irradiation unit capable of irradiating the gas with second light having a second wavelength shorter than the first wavelength, an irradiation position adjustment unit capable of controlling the irradiation position of the first light in the gas, a gas analysis unit capable of analyzing components of the gas based on the first light that has passed through the gas, and a gas visualization unit capable of visualizing a concentration distribution of the gas based on the second light that has passed through the gas. The irradiation position adjustment unit controls the irradiation position of the first light in the gas based on the visualized concentration distribution of the gas. [Brief explanation of the drawings]

[0006] [Figure 1] 1 is a schematic diagram illustrating a gas detection device according to an embodiment of the present invention; [Figure 2] 2 is a schematic diagram of the light source in FIG. 1 as viewed from the direction of line AA. [Figure 3] 10 is a photograph illustrating an optical image detected by a detection unit. [Figure 4] 10 is a graph illustrating a detection result when a gas visualization unit is provided. [Figure 5] 10 is a graph illustrating a detection result when a gas visualization unit is not provided. [Figure 6] 10A and 10B are schematic diagrams illustrating a gas detection device according to another embodiment. [Figure 7] 10A and 10B are schematic diagrams illustrating a gas detection device according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0007] Hereinafter, embodiments will be illustrated with reference to the drawings. In the drawings, like components are designated by like reference numerals and detailed descriptions thereof will be omitted where appropriate. FIG. 1 is a schematic diagram illustrating a gas detection device 1 according to the present embodiment. In FIG. 1, the light 21a and the light 22c are drawn apart from each other to avoid clutter. FIG. 2 is a schematic diagram of the light source 2 in FIG. 1 as viewed from the direction of line AA. As shown in FIG. 1, gas detection device 1 has light source 2, irradiation position adjustment unit 3, light splitting unit 4, gas analysis unit 5, gas visualization unit 6, and controller 7.

[0008] As shown in FIGS. 1 and 2, the light source 2 has, for example, a first irradiating section 21 and a second irradiating section 22. The first irradiator 21 irradiates the gas 100 released into the space with light 21a (which corresponds to an example of the first light). The wavelength of the light 21a is, for example, 0.7 μm or more (which corresponds to an example of the first wavelength). The light 21a is, for example, infrared or near-infrared light. The first irradiator 21 is, for example, a quantum cascade laser (QCL) including a compound semiconductor. If the first irradiator 21 is a quantum cascade laser, it becomes easy to reduce the size of the first irradiator 21.

[0009] Second irradiator 22 irradiates gas 100 released into the space with light 22c (which corresponds to an example of second light). The second irradiation unit 22 includes, for example, a light-emitting unit 22a and a filter 22b that forms a dot pattern. The light-emitting unit 22a emits light 22c. The wavelength of the light 22c (which corresponds to an example of the second wavelength) is shorter than the wavelength of the light 21a. The wavelength of the light 22c is, for example, 360 nm or more and 830 nm or less. The light 22c is, for example, visible light such as red light. The light-emitting unit 22a can be, for example, a light-emitting element or a discharge lamp. The light-emitting element can be, for example, a light-emitting diode, a laser diode, an organic light-emitting diode, or the like. In this case, if the light-emitting unit 22a is a light-emitting element, the second irradiation unit 22 can be easily miniaturized. Furthermore, the distance between the optical axis of the first irradiation unit 21 and the optical axis of the second irradiation unit 22 can be shortened.

[0010] At least one light-emitting unit 22a can be provided. When a plurality of light-emitting units 22a are provided, the plurality of light-emitting units 22a can be provided so as to surround the first irradiation unit 21 when viewed from a direction along the optical axis of the first irradiation unit 21. In this case, the plurality of light-emitting units 22a can be provided, for example, at positions that are point-symmetric with respect to the optical axis of the first irradiation unit 21.

[0011] Filter 22b forming the dot pattern is plate-shaped and is provided on the side of light emitting unit 22a where light 22c is emitted. Filter 22b forming the dot pattern has holes 22b1 penetrating in the thickness direction. Light 21a emitted from first irradiator 21 is irradiated onto gas 100 through holes 22b1. Light 22c emitted from light emitting unit 22a is irradiated onto gas 100 through filter 22b forming the dot pattern.

[0012] The surface of filter 22b that forms the dot pattern is provided with minute irregularities. If the surface of filter 22b that forms the dot pattern is provided with minute irregularities, it is possible to impart unevenness in brightness to light 22c irradiated from second irradiator 22. If light 22c has unevenness in brightness, it is possible to increase contrast when visualizing the concentration distribution of gas 100, which will be described later. In this case, if the arrangement of the projections and recesses has a certain regularity, interference fringes called moire may occur. Therefore, it is preferable that the arrangement of the projections and recesses is random. For example, the filter 22b that forms the dot pattern can be a filter that forms a so-called random dot pattern.

[0013] Here, the central axis of the light 22c emitted from the plurality of light-emitting units 22a does not necessarily have to be coaxial with the optical axis of the first irradiation unit 21. For example, the second irradiation unit 22 can be provided separately from the first irradiation unit 21.

[0014] However, if the optical axis of first irradiator 21 is coaxial with the optical axis of second irradiator 22, it becomes easier to control the irradiation position of light 21a in gas 100. The control of the irradiation position of light 21a will be described in detail later.

[0015] For example, if multiple light-emitting units 22a are arranged at positions that are point-symmetrical around the optical axis of the first irradiation unit 21, the optical axis of the first irradiation unit 21 can be made coaxial with the optical axis of the second irradiation unit 22.

[0016] Furthermore, light 21a and light 22c do not necessarily need to be irradiated simultaneously. For example, first, light 22c can be irradiated onto gas 100 to visualize the concentration distribution of gas 100, which will be described later. Next, based on the visualized concentration distribution of gas 100, the irradiation position of light 21a on gas 100 can be determined. Next, light 21a can be irradiated toward the determined irradiation position.

[0017] Irradiation position adjustment unit 3 controls the irradiation positions of light 21a and 22c in gas 100. Irradiation position adjustment unit 3 includes a mirror 31 and a drive unit 32, for example. At least one mirror 31 can be provided. The mirror 31 is provided so as to be able to swing. The mirror 31 reflects the incident light 21a, 22c and makes it incident on the gas 100. The light reflected from the mirror 31 may be parallel light or diverging light. However, if the light 22c is parallel light, it becomes easier to visualize the concentration distribution of the gas 100, which will be described later.

[0018] Driving unit 32 changes the angle of mirror 31, thereby changing the reflection angles of light 21a and 22c, and therefore the irradiation positions of light 21a and 22c in gas 100. Driving unit 32 may include a control motor such as a servo motor.

[0019] Light 21a and 22 that have passed through gas 100 are incident on light splitting unit 4. There is no particular limit to the distance between irradiation position adjustment unit 3 and light splitting unit 4. For example, gas detection device 1 can be used for remote detection, in which gas 100 is detected from a distant location. However, the use of gas detection device 1 is not limited to remote detection. The distance between irradiation position adjustment unit 3 and light splitting unit 4 may be short.

[0020] The light splitting unit 4 splits the light into light 21a and light 22c. For example, the light splitting unit 4 can be a beam splitter. For example, as shown in FIG. 1, the light splitting unit 4 transmits light 21a and reflects light 22c. The light splitting unit 4 illustrated in FIG. 1 is, for example, a half mirror. Furthermore, the light splitting unit 4 may be provided to be swingable, and the position of the light splitting unit 4 may be changed according to the swing position of the mirror 31 (the reflection position of the lights 21a and 22c). For example, the light splitting unit 4 may also be provided with a driver 32.

[0021] The gas 100 and the light 21a transmitted through the light splitting unit 4 are incident on the gas analysis unit 5. The gas analysis unit 5 analyzes the components of the gas 100 based on the light 21a transmitted through the gas 100. For example, an infrared absorption spectrum obtained by plotting the wave number of the incident light 21a on the horizontal axis and the transmittance (absorbance) on the vertical axis has a shape specific to each molecule. Therefore, the molecules contained in the gas 100, i.e., the components of the gas 100, can be analyzed based on the obtained infrared absorption spectrum.

[0022] Therefore, the gas analyzer 5 can be a sensor that detects infrared or near-infrared rays. The gas analyzer 5 can be, for example, an MCT sensor, which is a semiconductor sensor using mercury (Hg), cadmium (Cd), and tellurium (Te). The gas analyzer 5 transmits data on the detected components of the gas 100 to the controller 7.

[0023] 1, gas 100 is a gas released into space. When gas 100 is released into space, a distribution occurs in the concentration (density) of gas 100. Therefore, if the irradiation position of light 21a on gas 100 is constant, the detection value in gas analysis unit 5 may fluctuate depending on the detection timing in gas analysis unit 5. If the detection value fluctuates, there is a risk of a decrease in detection sensitivity and analysis accuracy.

[0024] Therefore, gas detection device 1 is provided with gas visualization section 6. Light 22c that has passed through gas 100 and been reflected by light splitting unit 4 is incident on gas visualization unit 6. Gas visualization unit 6 visualizes the concentration distribution of gas 100 based on light 22c that has passed through gas 100.

[0025] The gas visualization unit 6 includes, for example, an optical element 61 and a detection unit 62 . The optical element 61, for example, focuses the incident light 22c. The optical element 61 is, for example, a convex lens. The optical element 61 is not necessarily required and can be omitted. However, if the optical element 61 is provided, it is possible to improve the detection sensitivity and detection accuracy.

[0026] The detection unit 62 detects the light 22c that has passed through the gas 100 and is reflected by the light splitting unit 4. The detection unit 62 has, for example, a plurality of light receiving elements arranged in a plane. The detection unit 62 can be, for example, a CCD image sensor.

[0027] As described above, the concentration of the gas 100 released into the space is distributed. In this case, the refractive index of the light 22c in the high-concentration area is different from the refractive index of the light 22c in the low-concentration area. Therefore, the emission direction of the incident light 22c changes depending on the concentration of the gas 100. When the emission direction of the light 22c changes, a striped pattern or a hazy shadow appears in the optical image detected by the detection unit 62. The detector 62 transmits data of the detected optical image to the controller 7.

[0028] Controller 7 has a storage unit such as a semiconductor memory and a calculation unit such as a CPU. Controller 7 is, for example, a computer. The storage unit can store, for example, a control program that controls the operation of elements provided in gas detection device 1, and a program that calculates the irradiation position of light 21a based on data of the optical image detected by detection unit 62. The storage unit can also temporarily store, for example, data of the optical image detected by detection unit 62.

[0029] For example, controller 7 calculates the irradiation position of light 21a in gas 100 based on data of the optical image detected by detection unit 62. Furthermore, for example, controller 7 controls the operation of irradiation position adjustment unit 3 based on a control program stored in the storage unit and the determined irradiation position of light 21a. Furthermore, for example, controller 7 can transmit data of the optical image detected by detection unit 62 and the determined irradiation position of light 21a to a display device, an external device, or the like.

[0030] Next, the control of the irradiation position of the light 21a will be further described. FIG. 3 is a photograph illustrating an optical image detected by the detection unit 62. As shown in FIG. If there is a distribution in the concentration of the gas 100 released into space, stripes or hazy shadows will appear in the optical image, as shown in FIG.

[0031] Therefore, by first differentiating the data of the optical image detected by the detection unit 62 with respect to space, it is possible to extract areas with large changes in density (areas with large differences (gradients) in pixel brightness). Extraction of areas with high density and little spatial change in density, surrounded by areas with large changes in density, can be performed by image processing. Furthermore, by combining this with processing that performs first differentiation with respect to time, it is also possible to calculate areas with little change in density. In areas with little change in density, the components of the gas 100 are stable, so if light 21a is irradiated onto these areas, the gas 100 released into space can be properly detected.

[0032] Furthermore, if the optical axis of the first irradiating unit 21 is coaxial with the optical axis of the second irradiating unit 22, the center of the obtained optical image will be the irradiation position of the light 21a. Therefore, the distance and direction to move the irradiation position of the light 21a can be calculated from the position of the part with little density change extracted by image processing and the center position of the optical image.

[0033] Furthermore, when detecting a low concentration gas 100 (a gas 100 containing trace components), it is possible to extract a portion of the gas 100 with a high concentration. In this way, it is possible to improve the detection sensitivity and the analytical accuracy. When detecting a low concentration gas 100, the distance and direction to move the irradiation position of the light 21a can be determined in the same manner as described above.

[0034] Based on the determined distance and direction, controller 7 controls the irradiation position of light 21a in gas 100. For example, controller 7 controls driver 32 to change the angle of mirror 31, thereby controlling the irradiation position of light 21a in gas 100. That is, irradiation position adjuster 3 controls the irradiation position of light 21a in gas 100 based on the visualized concentration distribution of gas 100.

[0035] As described above, gas detection device 1 according to the present embodiment can irradiate light 21a to a portion of gas 100 released into space where there is little change in concentration. Therefore, even if there is a distribution in the concentration of gas 100, it is possible to prevent a decrease in detection sensitivity and analysis accuracy. Furthermore, even when detecting gas 100 with a low concentration, it is possible to improve detection sensitivity and analysis accuracy. In other words, gas detection device 1 according to the present embodiment can appropriately detect gas 100 released into space.

[0036] Fig. 4 is a graph illustrating the detection results when the gas visualization unit 6 is provided. Fig. 5 is a graph illustrating the detection results when the gas visualization unit 6 is not provided. That is, Fig. 5 shows the case where the gas 100 is detected by simply irradiating the gas 100 with light 21a without detecting the concentration distribution of the gas 100, and it can be seen that the amount of absorption is reduced because the detection is performed in an area with a low CO2 gas concentration. Note that the gas 100 in Figures 4 and 5 is CO2 gas. Figure 4 shows measurements at a location where the partial pressure of gas 100 is high at 5 atm, while Figure 5 shows measurements at a location where the partial pressure is low, i.e., where the concentration is low at 1 atm. This shows that the transmittance changes significantly, which means that the measurement accuracy has decreased. As is clear from FIGS. 4 and 5, by detecting the concentration distribution of the gas 100 using the gas visualization unit 6, it is possible to significantly improve the detection sensitivity and the analytical accuracy.

[0037] FIG. 6 is a schematic view illustrating a gas detection device 1a according to another embodiment. As shown in FIG. 6, gas detection device 1 a includes light source 2 , irradiation position adjustment unit 3 , light splitting unit 4 a , gas analysis unit 5 , gas visualization unit 6 , and controller 7 .

[0038] The light splitting unit 4a splits the light into light 21a and light 22c. For example, the light splitting unit 4a has a hole 4a1 penetrating in the thickness direction. For example, as shown in FIG. 6, the light 21a transmitted through the gas 100 enters the gas analysis unit 5 through the hole 4a1 provided in the light splitting unit 4a. The light 22c transmitted through the gas 100 is reflected near the periphery of the hole 4a1 provided in the light splitting unit 4a and enters the gas visualization unit 6.

[0039] That is, the light splitting unit 4a having the hole 4a1 can also split the light 21a and the light 22c. Note that the light splitting unit may be any unit that can split the light 21a and the light 22c. For example, the light splitting unit may be a prism.

[0040] FIG. 7 is a schematic view illustrating a gas detection device 1b according to another embodiment. FIG. 7 shows a case where a plurality of gases 100a to 100c are detected at relatively distant positions. As shown in FIG. 7, an irradiation position adjustment unit 3 can be provided on one side of the multiple gases 100a-100c, and a light splitting unit 4 (4a) can be provided on the opposite side of each of the multiple gases 100a-100c from the irradiation position adjustment unit 3. Each of the multiple light splitting units 4 (4a) can be connected to a gas analysis unit 5 and a gas visualization unit 6 using, for example, a light guide 8 such as an optical fiber or an optical system equipped with a lens and a reflector. A moving unit 3a can also be provided to move the position of the irradiation position adjustment unit 3. The moving unit 3a facilitates irradiating the multiple gases 100a-100c with light 21a and 22c at appropriate positions, even if the multiple gases 100a-100c are located far apart. The gases 100a-100c may be the same gas species or different gas species. In the case of different gas species, the wavelength of light 21a can be changed to analyze the multiple different gas species.

[0041] The controller 7 controls at least one of the irradiation position adjusting unit 3 and the moving unit 3a to irradiate the gas to be measured with the light 21a, 22c. In this way, it is possible to appropriately detect each of the plurality of gases 100a to 100c.

[0042] Furthermore, the gas analysis unit 5, gas visualization unit 6, and controller 7 can be combined into one unit. Therefore, the cost of the gas detection device 1b can be reduced compared to when a gas detection device 1 (1a) is provided for each of the plurality of gases 100a to 100c.

[0043] Next, a gas detection method according to this embodiment will be illustrated. The gas detection method according to this embodiment can be carried out using, for example, gas detection device 1 (1a, 1b). The gas detection method is a gas detection method in which gas 100 is irradiated with light 21a and light 22c. The gas detection method may include, for example, the following steps. A step of visualizing the concentration distribution of gas 100 based on light 22c transmitted through gas 100. A step of controlling the irradiation position of light 21a in gas 100 based on the visualized concentration distribution of gas 100. A step of analyzing the components of the gas 100 based on the light 21a transmitted through the gas 100.

[0044] In this case, the wavelength of the light 21a can be set to 0.7 μm or more. The light 22c can be visible light. In the step of visualizing the concentration distribution of the gas 100, the concentration distribution of the gas 100 can be visualized using the Schlieren method. The contents of each step can be the same as those described above, so detailed explanations will be omitted.

[0045] Although several embodiments of the present invention have been described above, these embodiments are presented by way of example only and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, modifications, etc. can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as set forth in the claims. Furthermore, the above-described embodiments can be implemented in combination with each other. [Explanation of symbols]

[0046] REFERENCE SIGNS LIST 1 gas detection device, 1a gas detection device, 1b gas detection device, 2 light source, 3 irradiation position adjustment unit, 4 light splitting unit, 5 gas analysis unit, 6 gas visualization unit, 7 controller, 21 first irradiation unit, 21a light, 22 second irradiation unit, 22c light,

Claims

1. a first irradiating unit capable of irradiating the gas released into the space with first light having a first wavelength; a second irradiation unit capable of irradiating the gas with second light having a second wavelength shorter than the first wavelength; an irradiation position adjustment unit capable of controlling an irradiation position of the first light in the gas; a gas analyzer capable of analyzing components of the gas based on the first light transmitted through the gas; a gas visualization unit capable of visualizing a concentration distribution of the gas based on the second light transmitted through the gas; Equipped with The gas detection device, wherein the irradiation position adjustment unit controls the irradiation position of the first light in the gas based on the visualized concentration distribution of the gas.

2. the first wavelength is 0.7 μm or more; 2. The gas detection device according to claim 1, wherein the first irradiating unit is a quantum cascade laser.

3. 3. The gas detection device according to claim 1, wherein the second light is visible light.

4. 4. The gas detection device according to claim 1, wherein the second irradiating unit further has a filter that forms a dot pattern, and the second light is irradiated onto the gas via the filter that forms the dot pattern.

5. A gas detection method for irradiating a gas released into a space with a first light having a first wavelength and a second light having a second wavelength shorter than the first wavelength, the method comprising: visualizing a concentration distribution of the gas based on the second light transmitted through the gas; controlling an irradiation position of the first light in the gas based on the visualized concentration distribution of the gas; analyzing components of the gas based on the first light transmitted through the gas; A gas detection method comprising:

6. the first wavelength is 0.7 μm or more; the second light is visible light; 6. The gas detection method according to claim 5, wherein the step of visualizing the gas concentration distribution uses a Schlieren method to visualize the gas concentration distribution.

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