Leaked gas analysis device, leaked gas analysis system, and leaked gas analysis method

Abstract

The present application relates to a leaked gas analysis device for analyzing a leaked gas in a field. The leaked gas analysis device acquires image data obtained by using an imaging device to image a field and extracts, from the image data, both first luminance information corresponding to a gas non-leakage region and second luminance information corresponding to a gas leakage region. Column density information relating to the column density of the leaked gas in the gas leakage region is calculated on the basis of the first luminance information, the second luminance information, and the gas non-leakage region column density of a gas component corresponding to the leaked gas in the gas non-leakage region.

Description

Leak gas analyzer, leak gas analysis system, and leak gas analysis method

[0001] This application claims priority to Japanese Patent Application No. 2024-147038, filed with the Japan Patent Office on August 29, 2024, the contents of which are incorporated herein by reference.

[0002] Carbon dioxide, which is produced when fossil fuels such as oil and coal are burned, is considered to be one of the causes of global warming. Various efforts have been made to reduce carbon dioxide emissions in plant facilities such as thermal power plants. One such effort is known as carbon dioxide capture, utilization, and storage (CCUS), which effectively utilizes carbon dioxide separated and extracted from exhaust gases from plant facilities.

[0003] In CCUS, carbon dioxide separated and extracted from exhaust gas is stored underground in a specified field, and it is necessary to manage whether the stored carbon dioxide from the field leaks to the surface as leaked gas. For example, Patent Document 1 discloses a technology for detecting leaked gas in such fields, in which an infrared camera mounted on a mobile object such as a drone continuously captures images of the field, and identifies the location of gas leaks in the field based on changes in brightness distribution between two successive image data in a chronological order.

[0004] JP 2024-48687 A

[0005] When detecting leaked gas based on image data captured while moving through a field using a mobile body equipped with an infrared camera, as in Patent Document 1, in order to obtain good detection accuracy, it is required that there is little variation in the shade of, for example, asphalt, and the conditions under which leaked gas can be detected are limited.

[0006] Furthermore, when measuring the concentration of leaked gas at a leak location where leaked gas has been detected, it is necessary to take a contact-type concentration meter to the leak location to measure. However, since the measurement results from a contact-type concentration meter are obtained at a single point within the leak location, there will be a large error when measuring the concentration of leaked gas at a leak location that is relatively large.

[0007] To solve this problem, it is possible to calculate the concentration of leaked gas from image data captured by an infrared camera. However, this method requires measuring the ground temperature and emissivity in advance to determine the radiation intensity of the field. However, if the field to be measured is large, it is not realistic to measure the ground temperature and emissivity over a wide area of ​​the field.

[0008] At least one embodiment of the present disclosure has been made in consideration of the above-mentioned circumstances, and aims to provide a leakage gas analysis device, a leakage gas analysis system, and a leakage gas analysis method that can simply and accurately measure information regarding the concentration of leakage gas in the field.

[0009] In order to solve the above problem, a leakage gas analyzer according to at least one embodiment of the present disclosure is a leakage gas analyzer for analyzing leakage gas in a field, and includes: an image data acquisition unit for acquiring image data of the field captured using an imaging device; a brightness information extraction unit for extracting, from the image data, first brightness information corresponding to a gas non-leakage area in the field where the leakage gas is absent, and second brightness information corresponding to a gas leakage area in the field where the leakage gas is present; and a pillar density information calculation unit for calculating pillar density information regarding the pillar density of the leakage gas in the gas leakage area based on the first brightness information, the second brightness information, and the gas non-leakage area pillar density of a gas component corresponding to the leakage gas in the gas non-leakage area.

[0010] In order to solve the above problem, a leakage gas analysis system according to at least one embodiment of the present disclosure comprises a leakage gas analysis device according to at least one embodiment of the present disclosure, and a mobile body equipped with the imaging device and capable of moving on the field.

[0011] In order to solve the above-mentioned problems, a leakage gas analysis method according to at least one embodiment of the present disclosure is a leakage gas analysis method for analyzing leakage gas in a field, comprising: a step of acquiring image data of the field using an imaging device; a step of extracting, from the image data, first brightness information corresponding to a gas non-leakage area in the field where the leakage gas is absent, and second brightness information corresponding to a gas leakage area in the field where the leakage gas is present; and a step of calculating column density information regarding the column density of the leakage gas in the gas leakage area based on the first brightness information, the second brightness information, and the gas non-leakage area column density of the gas component corresponding to the leakage gas in the gas non-leakage area.

[0012] According to at least one embodiment of the present disclosure, it is possible to provide a leakage gas analysis device, a leakage gas analysis system, and a leakage gas analysis method that can simply and accurately measure information related to the concentration of leakage gas in a field.

[0013] 2 is a schematic diagram showing a field according to an embodiment from a substantially horizontal direction. FIG. 3 is an overall configuration diagram of a leakage gas analysis system according to an embodiment. FIG. 4 is a schematic diagram showing an example of mounting the temperature information measurement sensor of FIG. 2 on a mobile body (raised position). FIG. 5 is a schematic diagram showing an example of mounting the temperature information measurement sensor of FIG. 2 on a mobile body (lowered position). FIG. 6 is an example of analysis of image data by the leakage determination unit and brightness information extraction unit of FIG. 2. FIG. 7 is a diagram showing a characteristic function used in the column density information calculation unit of FIG. 2. FIG. 8 is a flowchart showing a leakage gas analysis method implemented by the leakage gas analysis system of FIG. 2. FIG. 9 is an example of image data including a plurality of image frames acquired by the image data acquisition unit of FIG. 2. FIG. 10 is a diagram showing several characteristic functions with different temperature differences. FIG. 11 is a diagram showing a plurality of characteristic functions corresponding to different ground temperatures. FIG. 12 is an example of a movement path of a mobile body on a field.

[0014] Hereinafter, several embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the configurations described as embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present disclosure.

[0015] First, a field F to be analyzed by a leakage gas analysis system 1 according to at least one embodiment of the present disclosure will be described with reference to Fig. 1. Fig. 1 is a schematic diagram showing the field F according to one embodiment from a substantially horizontal direction.

[0016] The field F has a ground surface 3 extending in a substantially horizontal direction. The ground surface 3 is preferably basically flat, but may have some unevenness. The ground surface 3 has a sufficient area, and the atmosphere A is filled above it.

[0017] Any position on the field F can be expressed in a three-dimensional coordinate system (X, Y, Z) defined by the X-axis and Y-axis, which are orthogonal coordinate axes that define an approximately horizontal plane, and the Z-axis that is perpendicular to the XY plane.

[0018] A detection target gas is stored in the ground 3. The type of detection target gas is not limited, but an example is carbon dioxide separated and extracted from exhaust gas generated by fuel combustion in plant equipment such as a thermal power plant. FIG. 1 shows a state in which a portion of the detection target gas stored underground in the ground 3 leaks to the surface as leakage gas Gr. In the following description, a region of the field F from which the leakage gas Gr does not leak is referred to as a gas non-leakage region Rn, and a region from which the leakage gas Gr leaks is referred to as a gas leakage region Re.

[0019] Next, a description will be given of a leakage gas analysis system 1 for analyzing the leakage gas Gr in the above-mentioned field F. Fig. 2 is a diagram showing the overall configuration of the leakage gas analysis system 1 according to one embodiment. The leakage gas analysis system 1 includes a mobile body 10 that can move on the field F, and a leakage gas analysis device 100 that can communicate with the mobile body 10 via a wireless communication network 50.

[0020] The mobile body 10 is, for example, a drone aircraft that can move over the field F by remote control by an operator or automatic control. The mobile body 10 is equipped with an imaging device 12, a position information measurement sensor 14, and a temperature information measurement sensor 16 as various components for detecting leaked gas Gr in the field F.

[0021] The imaging device 12 is configured to capture an image of the field F using imaging light having a wavelength corresponding to the leaked gas Gr. For example, when carbon dioxide is treated as the leaked gas Gr, an infrared camera using infrared light having a wavelength of approximately 4.3 μm is used as the imaging light. When a hydrocarbon such as methane is treated as the leaked gas Gr, the wavelength of the imaging light may be approximately 2.3 to 3.7 μm.

[0022] Although the imaging direction of the imaging device 12 is not limited, in this embodiment, the imaging device 12 has an imaging direction that is approximately vertically downward relative to the moving body 10, and can obtain a two-dimensional image corresponding to the XY plane. This two-dimensional image can be output as image data Dg in which a large number of pixels, each having a brightness value, are collected in a matrix.

[0023] The position information measuring sensor 14 is configured to measure position information Ip relating to the position of the mobile object 10 on which the position information measuring sensor 14 is mounted, and is, for example, a GPS sensor. The position information Ip is measured as coordinate data representing, for example, an arbitrary position on the field F in a three-dimensional coordinate system (X, Y, Z).

[0024] In addition, the position information Ip measured by the position information measuring sensor 14 is, strictly speaking, information regarding the position of the sensor itself, but since the position information measuring sensor 14 is mounted in a position sufficiently close to the mobile body 10 relative to the size of the field F, the position information Ip may also be considered as information regarding the position of the mobile body 10 or the position of other components (e.g., the imaging device 12) mounted on the mobile body 10.

[0025] The temperature information measurement sensor 16 is configured to measure temperature information It related to the temperature at the position of the temperature information measurement sensor 16. Because the temperature information measurement sensor 16 is mounted on the moving body 10, the temperature information measurement sensor 16 can measure temperature information It corresponding to various positions on the field F depending on the position of the moving body 10.

[0026] 3A and 3B are schematic diagrams showing an example of mounting the temperature information measurement sensor 16 of FIG. 2 on the mobile body 10. In this example, the temperature information measurement sensor 16 is a contact thermometer, and is supported by being suspended from the main body 10a of the mobile body 10 via a wire 18. A winch device 15 capable of winding up the wire 18 is mounted on the main body 10a, and by adjusting the amount of winding by the winch device 15, the temperature information measurement sensor 16 suspended from the wire 18 can be raised and lowered relative to the main body 10a.

[0027] 3A shows a state in which the temperature information measurement sensor 16 is in the raised position. In this case, the temperature information measurement sensor 16 is located close to the main body 10a and can measure the atmospheric temperature Ta in the vicinity of the moving body 10 as the temperature information It. On the other hand, FIG. 3B shows a state in which the temperature information measurement sensor 16 is in the lowered position. In this case, the temperature information measurement sensor 16 is located close to the ground 3 and can measure the ground temperature Tg in the vicinity of the ground 3 as the temperature information It.

[0028] Returning to Fig. 2, the leakage gas analyzer 100 is a device for analyzing leakage gas Gr in a field F using data acquired by the aforementioned components mounted on the mobile body 10. The leakage gas analyzer 100 has a hardware configuration including an electronic processing device such as a computer, and by executing a pre-installed program, controls the operation of the mobile body 10 and performs calculation processing using various data acquired by the mobile body 10. Furthermore, the leakage gas analyzer 100 is connected to the mobile body 10 via a wireless communication network 50, thereby enabling transmission and reception of various data between the mobile body 10 and the mobile body 10.

[0029] The leak gas analysis device 100 includes a position information acquisition unit 102, a distance information acquisition unit 103, a temperature information acquisition unit 104, a volume density information acquisition unit 105, a movement control unit 106, an imaging control unit 108, an image data acquisition unit 110, a leak determination unit 111, a brightness information extraction unit 112, and a column density information calculation unit 114.

[0030] The position information acquisition unit 102 is configured to acquire position information Ip measured by the position information measurement sensor 14. The position information Ip acquired by the position information acquisition unit 102 is stored in a storage means such as a memory (not shown) in association with the measurement time by the position information measurement sensor 14, so that it can be associated with other information (image data Dg, distance information Id, temperature information It, volume density information Im, etc.) acquired from other components mounted on the mobile object 10.

[0031] The distance information acquisition unit 103 is configured to acquire distance information Id relating to the distance from the moving body 10 to an arbitrary object. In this embodiment, information relating to the distance (height H) from the moving body 10 to the ground 3 can be acquired as the distance information Id.

[0032] The temperature information acquisition unit 104 is a component for acquiring temperature information It measured by the temperature information measurement sensor 16. The temperature information It acquired by the temperature information acquisition unit 104 is stored in a storage means such as a memory (not shown) in association with the time of measurement by the temperature information measurement sensor 16, so that it can be associated with other information (image data Dg, position information Ip, distance information Id, volume density information Im, etc.) acquired from other components mounted on the mobile object 10.

[0033] The volume density information acquisition unit 105 is configured to acquire volume density information Im relating to the volume density of a gas component corresponding to the leaked gas Gr in the atmosphere A. The volume density information Im may be acquired as a measurement result by a sensor (not shown), or a preset value may be acquired. In the latter case, for example, a typical concentration value of carbon dioxide contained in the atmosphere A is known (approximately 400 ppm at an altitude up to 10 m), so the preset value may be acquired as the volume density information Im.

[0034] The movement control unit 106 is configured to control the movement of the moving body 10 in the field F. Specifically, the movement control unit 106 identifies the position of the moving body 10 in the field F based on the position information Ip acquired by the position information acquisition unit 102, and controls the drive of a propulsion device (not shown) provided in the moving body 10 so that the position moves along a predetermined target trajectory.

[0035] The imaging control unit 108 is configured to control the imaging operation by the imaging device 12. The imaging operation by the imaging device 12 is controlled so as to be performed at a predetermined timing in coordination with the movement control of the moving body 10 by the movement control unit 106 described above.

[0036] The image data acquisition unit 110 is a component for acquiring image data Dg from the imaging device 12. The image data Dg is acquired as two-dimensional image data including a large number of pixels, each having a brightness value. The image data Dg acquired by the image data acquisition unit 110 is stored in a storage means such as a memory (not shown) in association with the time of image capture by the imaging device 12, so that it can be associated with other information (position information Ip, distance information Id, temperature information It, volume density information Im, etc.) acquired from other components mounted on the mobile object 10.

[0037] The leakage determination unit 111 is configured to determine the presence or absence of leaked gas Gr in the field F based on the image data Dg. In the gas leakage region Re of the image data Dg, the imaging light is absorbed by the leaked gas Gr, so the pixel brightness values ​​tend to be lower than in the gas non-leakage region Rn. Therefore, the leakage determination unit 111 can determine the presence or absence of leaked gas Gr in the field F based on whether the image data Dg can identify a gas leakage region Re where pixels with relatively low brightness values ​​are gathered.

[0038] The luminance information extraction unit 112 is configured to extract luminance information from the image data Dg acquired by the image data acquisition unit 110, based on the determination result by the leakage determination unit 111. Specifically, the luminance information extraction unit 112 analyzes the image data Dg to identify gas non-leakage regions Rn and gas leakage regions Re in the image data Dg, and extracts first luminance information K1 corresponding to the gas non-leakage regions Rn and second luminance information K2 corresponding to the gas leakage regions Re.

[0039] Since the pixel brightness values ​​in the gas non-leakage region Rn tend to be higher than those in the gas leak region Re, the gas non-leakage region Rn can be identified as a region of the image data Dg where pixels having brightness values ​​equal to or greater than a predetermined reference value are gathered. Also, since the pixel brightness values ​​in the gas leak region Re tend to be lower than those in the gas non-leakage region Rn, the gas leak region Re can be identified as a region of the image data Dg where pixels having brightness values ​​less than a predetermined reference value are gathered.

[0040] The first luminance information K1 is information relating to a luminance value P0 corresponding to a gas non-leakage region Rn in the field F. This luminance value P0 may be the luminance value of a representative pixel in the gas non-leakage region Rn, or may be a statistical value (e.g., average value) calculated from the luminance values ​​of multiple pixels in the gas non-leakage region Rn. The second luminance information K2 is information relating to a luminance value P corresponding to a gas leak region Re in the field F. This luminance value P may be the luminance value of a representative pixel in the gas leak region Re, or may be a statistical value (e.g., average value) calculated from the luminance values ​​of multiple pixels in the gas leak region Re.

[0041] Here, Fig. 4 is an example of image data Dg acquired by the image data acquisition unit 110 of Fig. 2. The image data Dg shown in Fig. 4 was obtained by imaging the field F vertically downward from the moving body 10 using the imaging device 12, and therefore has the ground 3 corresponding to the XY plane as the background. When the luminance values ​​of each pixel included in the image data Dg are analyzed, if there is a group of pixels whose luminance values ​​are lower than their surroundings due to absorption of imaging light by the leaked gas Gr, the leakage determination unit 111 determines that leaked gas Gr is present on the field F. Furthermore, the luminance information extraction unit 112 identifies regions where there is no leaked gas Gr as gas non-leak regions Rn and extracts first luminance information K1 based on the pixels corresponding to the gas non-leak regions Rn, and identifies regions where there is leaked gas Gr as gas leak regions Re and extracts second luminance information K2 based on the pixels corresponding to the gas leak regions Re.

[0042] 2 , the column density information calculation unit 114 is configured to calculate information regarding the column density N of the leaked gas Gr in the gas leakage region Re, based on the first luminance information K1 and the second luminance information K2 extracted by the luminance information extraction unit 112. The column density N is the gas density per unit area in the gas leakage region Re in the image data Dg.

[0043] Here, the brightness value P of a pixel in the gas leakage region Re of the image data Dg can generally be expressed by the following equation using the infrared radiation intensity I0 from the ground 3, the attenuation constant A (>0), and the column density N of the leaking gas Gr: P=k×I0×exp(−A×N) (1)

[0044] By modifying the above equation (1), the column density N of the leaked gas Gr is expressed as follows using the brightness value P0 of the pixel in the gas non-leakage region Rn and the gas non-leakage region column density N0: N=Fx(P)=N0-log(P / P0) / A (2)

[0045] Here, the gas non-leakage region column density N0 is calculated by the following formula using the altitude H (distance from the ground 3) of the moving body 10 in the gas non-leakage region Rn specified by the distance information Id acquired by the distance information acquisition unit 103, and the concentration n0 of the detection target gas in the gas non-leakage region Rn specified by the volume density information Im acquired by the volume density information acquisition unit 105. N0=n0×H (3)

[0046] The column density information calculation unit 114 calculates the luminance value P of the pixel in the gas leakage region Re based on the second luminance information K2 extracted by the luminance information extraction unit 112 (for example, the luminance value P is the average value or representative value of the luminance values ​​of each pixel in the gas leakage region Re based on the second luminance information K2), and inputs the luminance value P into the above equation (2), thereby being able to determine the column density N of the leaked gas Gr.

[0047] The relationship between the brightness value P of a pixel in the gas leakage region Re and the column density N of the leaked gas Gr is expressed by the characteristic function fx shown in equation (2) above. Fig. 5 is a diagram showing an example of the characteristic function fx used by the column density information calculation unit 114 of Fig. 2. In this example, the vertical axis is expressed as a logarithmic axis, and the characteristic function fx is shown linearly. Using this characteristic function fx, the column density information calculation unit 114 can calculate the column density N of the leaked gas Gr corresponding to the brightness value P of a pixel in the gas leakage region Re.

[0048] Unlike the above equation (1), the calculation formula shown in equation (2) does not include the infrared radiation intensity I0 from the ground 3, and therefore there is no need to measure the infrared radiation intensity I0 of the ground 3 in advance. Therefore, even when the field F is vast, it is possible to accurately obtain information regarding the column density of the leaked gas Gr corresponding to the brightness value P of the pixel in the gas leakage region Re.

[0049] Strictly speaking, the above equation (2) uses brightness values ​​P and P0 corresponding to the gas non-leakage region Rn and the gas leakage region Re, which are located at different positions. However, since the range included in the image data Dg is sufficiently narrow compared to the size of the field F, the two can be considered to be in approximately the same position, and this does not pose a problem.

[0050] Next, a description will be given of a leakage gas analysis method that can be performed by the leakage gas analysis system 1 having the above configuration. Fig. 6 is a flowchart showing the leakage gas analysis method performed by the leakage gas analysis system 1 of Fig. 2.

[0051] First, the moving body 10 is controlled to move along a predetermined target trajectory on the field F based on a control signal from the movement control unit 106 of the leakage gas analyzer 100 (step S1). In the moving moving body 10, an imaging operation is performed at a predetermined timing in the imaging device 12 mounted on the moving body 10 based on a control signal from the imaging control unit 108 (step S2). The content captured by the imaging device 12 is transmitted as image data Dg to the leakage gas analyzer 100 via the wireless communication network 50.

[0052] Next, in the leak gas analyzer 100, the image data acquisition unit 110 acquires the image data Dg received via the wireless communication network 50 (step S3). The image data Dg acquired by the image data acquisition unit 110 is analyzed, and the leakage determination unit 111 determines the presence or absence of leak gas Gr in the field F (step S4). The luminance information extraction unit 112 identifies the gas non-leakage region Rn and the gas leak region Re included in the image data Dg and extracts the first luminance information K1 and the second luminance information K2 (step S5). Next, the column density information calculation unit 114 calculates the column density N of the leak gas Gr corresponding to the luminance value P of the pixel in the gas leak region Re using the arithmetic expression (2) above, based on the first luminance information K1 and the second luminance information K2 obtained in step S5 (step S6).

[0053] The column density N calculated in this manner can be used for various analyses related to the leaked gas Gr in the field F. For example, by applying the column density N of the leaked gas Gr obtained as a calculation result to the area of ​​the gas leakage region Re identified from the field F, the total leakage amount of the leaked gas Gr in the field F can be calculated.

[0054] In the above-described embodiment, the image data Dg used to calculate the pillar density N in the pillar density information calculation unit 114 is exemplified as a single still image captured by the imaging device 12, but the image data Dg may also include multiple image frames f1, f2, .... In this case, the image frames f1, f2, ... included in the image data Dg can be obtained, for example, by continuously capturing images of the field F with the imaging device 12 mounted on the moving body 10 while the moving body 10 is moving relative to the field F. The positions captured by the image frames f1, f2, ... can be adjusted as appropriate based on, for example, the moving speed of the moving body and the imaging interval.

[0055] 7 shows an example of image data Dg including a plurality of image frames f1, f2, ... acquired by the image data acquisition unit 110 of Fig. 2. In this example, while the moving body 10 moves in a fixed direction relative to the field F, the imaging device 12 mounted on the moving body 10 repeatedly performs an imaging operation at predetermined intervals, thereby obtaining image data Dg including a plurality of image frames f1, f2, ....

[0056] 7 illustrates image data Dg including three image frames f1 to f3 captured in chronological order as a moving object 10 passes over a leaking gas Gr on a field F. Image frame f1, captured at the earliest time, covers the entire image of the gas non-leakage region Rn and does not include the gas leakage region Re. Image frame f2, captured next, includes a portion of the gas leakage region Re. Image frame f3, captured next, includes the entire gas leakage region Re.

[0057] The brightness information extraction unit 112 may identify the gas non-leakage region Rn based on the image frame f1, which was captured a predetermined number of frames before the image frame f3 containing the gas leak region Re, among the multiple image frames f1 to f3 captured consecutively in this manner. In the example of Figure 7, the image frame f3 contains the entire gas leak region Re, and therefore the gas non-leakage region Rn is identified based on the image frame f1, which was captured a predetermined number of frames before the image frame f3. Since the image frame f1 does not contain the gas leak region Re and the entire image is the gas non-leakage region Rn, identifying the gas non-leakage region Rn based on the image frame f1 allows for accurate evaluation of the brightness value P0 of the pixels in the gas non-leakage region Rn, and as a result, the column density N of the leaked gas Gr can be accurately calculated using the above formula (2).

[0058] The column density information calculation unit 114 may also calculate the column density N of the leaking gas Gr based on the temperature information It acquired by the temperature information acquisition unit 104. As mentioned above, the relationship between the brightness value P of the pixel in the gas leakage region Re and the column density N of the leaking gas Gr is defined by the characteristic function fx shown in Figure 5, and the attenuation constant A included in the above equation (2) representing the characteristic function fx has been found to depend on the temperature information It, according to verification by the inventors. In particular, it has been found that the attenuation constant A depends on the temperature difference ΔT (= Tg - Ta) between the atmospheric temperature Ta and the ground temperature Tg acquired as the temperature information It.

[0059] Fig. 8 is a diagram showing how the characteristic function fx used by the column density information calculation unit 114 in Fig. 2 changes with the temperature difference ΔT. Fig. 8 shows characteristic functions fx1 to fx3, each having a damping constant A corresponding to a different temperature difference ΔT. When the temperature difference ΔT differs in this way, the damping constant A changes, and the characteristic function fx also changes.

[0060] Therefore, the column density information calculation unit 114 may acquire the relationship between the temperature difference ΔT and the attenuation constant A in advance as correlation data, and based on the correlation data, determine the attenuation constant A corresponding to the temperature difference ΔT identified from the temperature information It acquired by the temperature information acquisition unit 104. In this case, the atmospheric temperature Ta and the ground temperature Tg can each be acquired by raising and lowering the temperature information measurement sensor 16 with the winch device 15, as described above with reference to Figures 3A and 3B.

[0061] The column density information calculation unit 114 calculates the temperature difference ΔT based on the temperature information It acquired by the temperature information acquisition unit 104, and determines the attenuation constant A corresponding to the temperature difference ΔT. Then, using a characteristic function fx having the attenuation constant A, it calculates the column density N of the leaked gas Gr corresponding to the brightness value P of the pixel in the gas leakage region Re. In this way, by taking the temperature information It into consideration when calculating the column density N of the leaked gas Gr using the characteristic function fx, it is possible to calculate the column density N of the leaked gas Gr with greater accuracy.

[0062] Furthermore, the characteristic function fx for calculating the column density N of the leaked gas Gr from the brightness value P of the pixel in the gas leakage region Re depends on the ground temperature Tg. Therefore, the column density information calculation unit 114 may prepare in advance multiple characteristic functions fx4 to fx6 corresponding to different ground temperatures Tg, and select which characteristic function fx to use based on the brightness value P0 of the pixel in the gas non-leakage region Rn and the gas non-leakage region column density N0.

[0063] FIG. 9 is a diagram showing multiple characteristic functions fx4 to fx6 corresponding to different ground temperatures Tg. The column density information calculation unit 114 calculates the pixel brightness value P0 and gas non-leakage region column density N0 in the gas non-leakage region Rn identified from the image data Dg, and selects from among the multiple characteristic functions fx4 to fx6 one that is consistent with the calculation results. In FIG. 9, the pixel brightness value P0 and gas non-leakage region column density N0 in the gas non-leakage region Rn are consistent with characteristic function fx4, so characteristic function fx4 is selected. Using the characteristic function fx4 selected in this manner, the column density information calculation unit 114 can calculate the column density N of the leakage gas Gr corresponding to the pixel brightness value P in the gas leakage region Re.

[0064] Furthermore, the pillar density information calculation unit 114 may determine the attenuation constant A included in the characteristic function fx based on multiple image data Dg captured by the imaging device 12 at multiple different heights H relative to the ground 3 in the field F. In this case, the moving body 10 is operated at a first height H1 and a second height H2 that are different from each other, thereby acquiring first image data Dg1 and second image data Dg2 corresponding to each height H (note that the first height H1 and the second height H2 may be at the same position on the XY plane or may be at different positions from each other).

[0065] The luminance information extraction unit 112 then identifies gas non-leakage regions Rn for each of the first image data Dg1 and the second image data Dg2. The pillar density information calculation unit 114 then determines the attenuation constant A by solving the following equation using the luminance values ​​P1 and P2 of the pixels in each gas non-leakage region Rn and the pillar densities N1 and N2: N1=N2-log(P1 / P2) / A (4) Note that the pillar densities N1 and N2 can be calculated by applying the first altitude H1 and the second altitude H2 to the above equation (3), respectively.

[0066] The column density information calculation unit 114 can then apply the attenuation constant A determined by solving the above equation (4) to the aforementioned equation (2) to calculate the column density N of the leaked gas Gr corresponding to the brightness value P of the pixel in the gas leak region Re identified from the image data Dg.

[0067] When the attenuation constant A is determined in this manner by an operation involving a change in the altitude of the moving body 10, as shown in Figure 10, when the moving body 10 moves patrol along the X direction or Y direction to search for leaked gas Gr on the field F and detects leaked gas Gr in the gas leakage area Re, the altitude H at that position may be changed along the Z axis direction, and the imaging operation may be performed by the imaging device 12 at each of the first altitude H1 and the second altitude H2, thereby obtaining the first image data Dg1 and the second image data Dg2.

[0068] In addition, within the scope of the present disclosure, the components in the above-described embodiments may be replaced with well-known components as appropriate, and the above-described embodiments may be combined as appropriate.

[0069] The contents described in each of the above embodiments can be understood, for example, as follows.

[0070] 1) A leakage gas analyzer according to one embodiment is a leakage gas analyzer for analyzing leakage gas in a field, comprising: an image data acquisition unit for acquiring image data of the field captured using an imaging device; a brightness information extraction unit for extracting, from the image data, first brightness information corresponding to a gas non-leakage region of the field where the leakage gas is absent, and second brightness information corresponding to a gas leakage region of the field where the leakage gas is present; and a pillar density information calculation unit for calculating pillar density information regarding the pillar density of the leakage gas in the gas leakage region based on the first brightness information, the second brightness information, and the gas non-leakage region pillar density of a gas component corresponding to the leakage gas in the gas non-leakage region.

[0071] According to the above aspect 1), first luminance information corresponding to the gas non-leakage region and second luminance information corresponding to the gas leak region are extracted based on image data obtained by imaging the field using an imaging device. The first luminance information and second luminance information are then used to calculate column density information related to the column density of the leaked gas in the gas leak region, along with the gas non-leakage region column density of the gas component corresponding to the leaked gas in the gas non-leakage region. By using the column density information of the leaked gas calculated in this manner, the concentration and leak amount of the leaked gas in the field can be measured simply and accurately without measuring the temperature or emissivity of the ground.

[0072] 2) In another aspect, in the aspect 1), the gas non-leakage region column density is calculated based on the distance information corresponding to the gas non-leakage region and the volume density information, and the gas non-leakage region column density is calculated based on the distance information corresponding to the gas non-leakage region and the volume density information.

[0073] According to the above aspect 2), the gas non-leakage region column density used to calculate the column density information can be suitably calculated based on distance information regarding the distance from the imaging device to the gas non-leakage region and volume density information regarding the volume density of the gas component corresponding to the leaked gas in the gas non-leakage region.

[0074] 3) In another aspect, in the aspect 1) or 2) above, a leakage determination unit is further provided for determining the presence or absence of leaked gas in the field based on the image data, and the brightness information extraction unit identifies the gas non-leakage area and the gas leakage area based on the determination result of the leakage determination unit.

[0075] According to the above aspect 3), the presence or absence of gas leakage in the field is determined by analyzing the image data, and the gas non-leakage area and the gas leakage area can be suitably identified based on the determination result.

[0076] 4) In another aspect, in any one of the aspects 1) to 3) above, the image data includes a plurality of image frames captured continuously while the imaging device is moved relative to the field, and the brightness information extraction unit identifies the non-gas leakage area based on a second image frame captured a predetermined number of frames before a first image frame that includes the gas leakage area among the plurality of image frames.

[0077] According to the above aspect 4), the gas non-leakage region is identified using a second image frame captured a predetermined number of frames before a first image frame containing a gas leakage region, among a plurality of image frames included in the image data. Since such a second image frame does not contain a gas leakage region or contains a small proportion of the gas leakage region, the gas non-leakage region can be identified in an appropriate manner.

[0078] 5) In another aspect, in any one of the above aspects 1) to 4), a temperature information acquisition unit is further provided for acquiring temperature information including at least one of the atmospheric temperature and the ground temperature in the field, and the pillar density information calculation unit calculates the pillar density based on the temperature information.

[0079] According to the above aspect 5), the column density of the leaked gas is calculated taking into account temperature information including at least one of the atmospheric temperature and the ground temperature in the field, thereby allowing the column density information to be determined with high accuracy by taking into account the dependency of the column density on the temperature information.

[0080] 6) In another aspect, in the aspect 5), the column density information calculation unit determines an attenuation constant included in a characteristic function for calculating the column density corresponding to the first luminance information and the second luminance information based on the temperature information.

[0081] According to the above aspect 6), the damping constant included in the characteristic function, which is an arithmetic expression for calculating the column density of the leaked gas, can be suitably determined taking into account the dependency on the temperature information.

[0082] 7) In another aspect, in the aspect 6), the temperature information is a temperature difference between the atmospheric temperature and the ground temperature.

[0083] According to the above aspect 7), the attenuation constant included in the characteristic function, which is an arithmetic formula for calculating the column density of leaked gas, can be suitably determined based on the temperature difference between the atmospheric temperature and the ground temperature.

[0084] 8) In another aspect, in any one of the above aspects 5) to 7), the atmospheric temperature and the ground temperature are measured using a contact thermometer mounted on a mobile object flying over the field so that the contact thermometer can be raised and lowered.

[0085] According to the above aspect 8), by raising and lowering the contact thermometer mounted on the moving body, the air temperature and the ground temperature can be efficiently measured using the contact thermometer with excellent measurement accuracy.

[0086] 9) In another aspect, in the aspect 5) above, the column density information calculation unit calculates the column density from a plurality of characteristic functions corresponding to different ground temperatures that are prepared in advance, using the characteristic function that matches the brightness value of the pixel in the gas non-leakage region calculated based on the first brightness information and the gas non-leakage region column density.

[0087] According to the above aspect 9), a plurality of characteristic functions corresponding to different ground temperatures are prepared in advance, and a characteristic function that matches the luminance values ​​of pixels in the gas non-leakage region calculated based on the first luminance information and the gas non-leakage region column density is selected from among the plurality of characteristic functions.The selected characteristic function is then used to calculate the column density of the leakage gas, thereby making it possible to accurately determine the column density of the leakage gas while taking into account the influence of the ground temperature.

[0088] 10) In another aspect, in any one of the aspects 1) to 9) above, the image data acquisition unit acquires, as the image data, first image data and second image data captured by the imaging device at mutually different altitudes, and the pillar density information calculation unit determines an attenuation constant included in a characteristic function for calculating the pillar densities corresponding to the first brightness information and the second brightness information based on the brightness values ​​of pixels in the gas non-leakage region identified from the first image data, the gas non-leakage region pillar density calculated based on the first image data, the brightness values ​​of pixels in the gas non-leakage region identified from the second image data, and the gas non-leakage region pillar density calculated based on the second image data.

[0089] According to the above aspect 10), based on the first image data and the second image data captured at positions having different altitudes from the ground, the attenuation constant included in the characteristic function for calculating the degree of caution for leaked gas can be suitably determined based on the brightness values ​​of the pixels in each gas non-leakage area and the gas non-leakage area column density.

[0090] 11) In another aspect, in any one of the aspects 1) to 10) above, the pillar density information calculation unit calculates the pillar density N by the following equation: N=N0-log(P / P0) / A using a brightness value P0 of a pixel in the gas non-leakage region calculated based on the first brightness information, a brightness value P of a pixel in the gas leakage region calculated based on the second brightness information, the gas non-leakage region pillar density N0, and an attenuation constant A.

[0091] According to the above aspect 11), by using the above calculation formula, it is possible to suitably calculate the column density information of the leaked gas without using the temperature or emissivity of the ground in the field.

[0092] 12) In another aspect, in any one of the above aspects 1) to 11), the imaging device is an infrared camera.

[0093] According to the above aspect 12), by using an infrared camera as the imaging device, it is possible to suitably analyze leaked gases having absorption wavelengths in the infrared region.

[0094] 13) In another aspect, in any one of the above aspects 1) to 11), the leaked gas is carbon dioxide.

[0095] According to the above aspect 13), for example, if carbon dioxide stored underground in CCUS leaks, it is possible to measure the concentration and amount of carbon dioxide leaking in the field by calculating whether or not there has been a leak and the column density information of the leaked carbon dioxide.

[0096] 14) A leakage gas analysis system according to one aspect includes: a leakage gas analysis device according to any one of aspects 1) to 13) above; and a mobile body equipped with the imaging device and capable of moving on the field.

[0097] According to the above aspect 14), a system suitable for analyzing leaked gas can be provided by determining whether or not there is leaked gas on the field and calculating column density information of the leaked gas.

[0098] 15) A leakage gas analysis method according to one embodiment is a leakage gas analysis method for analyzing leakage gas in a field, comprising the steps of: acquiring image data of the field using an imaging device; extracting, from the image data, first luminance information corresponding to a gas non-leakage region of the field where the leakage gas is absent, and second luminance information corresponding to a gas leakage region of the field where the leakage gas is present; and calculating column density information relating to the column density of the leakage gas in the gas leakage region based on the first luminance information, the second luminance information, and the gas non-leakage region column density of a gas component corresponding to the leakage gas in the gas non-leakage region.

[0099] According to aspect 15 above, first luminance information corresponding to a gas non-leakage region and second luminance information corresponding to a gas leak region are extracted based on image data obtained by imaging a field using an imaging device. The first luminance information and second luminance information are then used to calculate column density information related to the column density of the leaked gas in the gas leak region, along with the gas non-leakage region column density of a gas component corresponding to the leaked gas in the gas non-leakage region. By using the column density information of the leaked gas calculated in this manner, the concentration and leak amount of the leaked gas in the field can be measured simply and accurately without measuring the temperature or emissivity of the ground.

[0100] REFERENCE SIGNS LIST 1 Gas leakage analysis system 3 Ground 10 Mobile body 10a Main body 12 Imaging device 14 Position information measurement sensor 15 Winch device 16 Temperature information measurement sensor 18 Wire 50 Wireless communication network 100 Gas leakage analysis device 102 Position information acquisition unit 103 Distance information acquisition unit 104 Temperature information acquisition unit 105 Volume density information acquisition unit 106 Movement control unit 108 Imaging control unit 110 Image data acquisition unit 111 Leakage determination unit 112 Brightness information extraction unit 114 Pillar density information calculation unit Dg Image data F Field Gr Leakage gas Id Distance information Im Volume density information Ip Position information It Temperature information K1 First brightness information K2 Second brightness information Re Gas leakage area Rn Non-leakage area Ta Atmospheric temperature Tg Ground temperature fx characteristic function

Claims

1. A leakage gas analyzer for analyzing leakage gas in a field, comprising: an image data acquisition unit for acquiring image data obtained by capturing an image of the field using an imaging device; a brightness information extraction unit for extracting, from the image data, first brightness information corresponding to a gas non-leakage area in the field where the leakage gas is absent, and second brightness information corresponding to a gas leakage area in the field where the leakage gas is present; and a column density information calculation unit for calculating column density information regarding the column density of the leakage gas in the gas leakage area based on the first brightness information, the second brightness information, and the gas non-leakage area column density of a gas component corresponding to the leakage gas in the gas non-leakage area.

2. The leakage gas analyzer of claim 1, further comprising: a distance information acquisition unit for acquiring distance information relating to the distance from the imaging device to the gas non-leakage area; and a volume density information acquisition unit for acquiring volume density information relating to the volume density of the gas component in the gas non-leakage area, wherein the gas non-leakage area column density is calculated based on the distance information corresponding to the gas non-leakage area and the volume density information.

3. A leakage gas analyzer as described in claim 1 or 2, further comprising a leakage determination unit for determining the presence or absence of leakage gas in the field based on the image data, and the brightness information extraction unit identifies the gas non-leakage area and the gas leakage area based on the determination result of the leakage determination unit.

4. A leakage gas analyzer as described in claim 1 or 2, wherein the image data includes a plurality of image frames captured successively while the imaging device is moved relative to the field, and the brightness information extraction unit identifies the non-leakage region based on a second image frame captured a predetermined number of frames before a first image frame that includes the gas leakage region among the plurality of image frames.

5. A leakage gas analysis device as described in claim 1 or 2, further comprising a temperature information acquisition unit for acquiring temperature information including at least one of atmospheric temperature and ground temperature in the field, and wherein the column density information calculation unit calculates the column density based on the temperature information.

6. The leakage gas analyzer according to claim 5, wherein the column density information calculation unit determines an attenuation constant included in a characteristic function for calculating the column density corresponding to the first brightness information and the second brightness information based on the temperature information.

7. The gas leakage analyzer according to claim 6, wherein the temperature information is the temperature difference between the atmospheric temperature and the ground temperature.

8. The leakage gas analyzer according to claim 5, wherein the atmospheric temperature and the ground temperature are measured using a contact thermometer mounted on a mobile object that flies over the field and can be raised and lowered.

9. The leakage gas analyzer according to claim 5, wherein the column density information calculation unit calculates the column density from a plurality of characteristic functions corresponding to different ground temperatures prepared in advance, using the characteristic function that matches the brightness value of the pixel in the gas non-leakage area calculated based on the first brightness information and the gas non-leakage area column density.

10. The leakage gas analyzer according to claim 1 or 2, wherein the image data acquisition unit acquires, as the image data, first image data and second image data captured by the imaging device at mutually different altitudes, and the column density information calculation unit determines an attenuation constant included in a characteristic function for calculating the column densities corresponding to the first brightness information and the second brightness information based on the brightness values ​​of pixels in the gas non-leakage region identified from the first image data, the gas non-leakage region column density calculated based on the first image data, the brightness values ​​of pixels in the gas non-leakage region identified from the second image data, and the gas non-leakage region column density calculated based on the second image data.

11. The leakage gas analyzer according to claim 1 or 2, wherein the column density information calculation unit calculates the column density N by the following formula: N=N0-log(P / P0) / A, using the brightness value P0 of the pixel in the gas non-leakage region calculated based on the first brightness information, the brightness value P of the pixel in the gas leakage region calculated based on the second brightness information, the gas non-leakage region column density N0, and an attenuation constant A.

12. The leak gas analyzer according to claim 1 or 2, wherein the imaging device is an infrared camera.

13. The leak gas analyzer according to claim 1 or 2, wherein the leak gas is carbon dioxide.

14. A leakage gas analysis system comprising: the leakage gas analysis device according to claim 1 or 2; and a mobile body equipped with the imaging device and capable of moving on the field.

15. A leakage gas analysis method for analyzing leakage gas in a field, comprising: a step of acquiring image data of the field using an imaging device; a step of extracting, from the image data, first luminance information corresponding to a gas non-leakage area in the field where the leakage gas is absent, and second luminance information corresponding to a gas leakage area in the field where the leakage gas is present; and a step of calculating column density information relating to the column density of the leakage gas in the gas leakage area based on the first luminance information, the second luminance information, and the gas non-leakage area column density of a gas component corresponding to the leakage gas in the gas non-leakage area.

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