Leak detection system, information processing device, and program

Abstract

This method allows for more accurate detection of gas leaks in a target space compared to a system where the reference value used for detecting gas leaks in the target space is uniform and not based on past measurement data. [Solution] The leak detection system comprises an optical scanning unit that scans a target space for detecting gas leaks with light of a predetermined wavelength, a light receiving unit that receives light that has passed through the target space and outputs a light receiving signal, and a detection unit that obtains a measured value representing the gas concentration in the target space from the light receiving signal and detects gas leaks in the target space by comparing the measured value with a predetermined reference value. The reference value is determined according to past measured values ​​obtained by the detection unit during periods when no gas has leaked into the target space, by scanning the target space with light using the optical scanning unit.

Description

Technical Field

[0001] The present invention relates to a leakage detection system, an information processing device, and a program.

Background Art

[0002] Patent Document 1 discloses a gas concentration detection system that scans a detection target space with laser light and detects the concentration of a detection gas based on a light reception signal obtained when the laser light passes through the detection target space.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] There is a technique for irradiating a target space with light to obtain a measurement value representing the concentration of a gas and detecting gas leakage by comparing the measurement value with a predetermined reference value. In such a technique, when scanning the target space with light to sequentially obtain measurement values, the magnitude of noise included in the measurement values may differ depending on differences in position in the target space or the like. In this case, if a reference value used for detecting gas leakage in the target space is uniformly determined, it may not be possible to accurately detect gas leakage. An object of the present invention is to more accurately detect gas leakage in a target space as compared with a case where a reference value used for detecting gas leakage in the target space is uniform regardless of past measurement values.

Means for Solving the Problems

[0005] The invention described in claim 1 is a leak detection system comprising: an optical scanning unit that scans a target space for detecting gas leakage with light of a predetermined wavelength; a light receiving unit that receives light that has passed through the target space and outputs a light receiving signal; and a detection unit that obtains a measured value representing the gas concentration in the target space from the light receiving signal and detects gas leakage in the target space by comparing the measured value with a predetermined reference value, wherein the reference value is determined according to past measured values ​​obtained by the detection unit during a period when no gas has leaked into the target space, by scanning the target space with light using the optical scanning unit. The invention described in claim 2 is a leak detection system according to claim 1, wherein the optical scanning unit sequentially irradiates light to a plurality of measurement points in the target space, the light receiving unit outputs the light receiving signal for each measurement point, and the detection unit compares the measurement value obtained for each measurement point with the reference value determined for each measurement point based on past measurement values. The invention described in claim 3 is a leak detection system according to claim 2, wherein the detection unit outputs information indicating that gas has leaked when the sum of the measured values ​​exceeds a predetermined threshold for any of the multiple measurement points where the measured value exceeds the reference value. The invention described in claim 4 is a leak detection system according to claim 2, wherein the detection unit detects gas leakage in the target space using the measured value of a measurement point among a plurality of measurement points where the intensity of light received by the light receiving unit is equal to or greater than a predetermined reference intensity. The invention described in claim 5 is a leak detection system according to claim 4, wherein the detection unit outputs information indicating that an abnormality has occurred without detecting a gas leak in the target space if the number of measurement points among the plurality of measurement points in which the intensity of light received by the light receiving unit is equal to or greater than the reference intensity is less than a predetermined number. The invention described in claim 6 is a leak detection system according to claim 2, wherein the target space is provided with a reflector that reflects light from the optical scanning unit, the light receiving unit receives light emitted from the optical scanning unit and reflected by the reflector, and the detection unit does not use the measured values ​​for the detection of gas leakage in the target space for measurement points among a plurality of measurement points where the light from the optical scanning unit does not reach the reflector. The invention described in claim 7 is an information processing device comprising: an acquisition unit that acquires a measured value representing the gas concentration in a target space calculated from a light reception signal of light scanned through the target space to detect a gas leak; and a setting unit that sets a reference value used to detect a gas leak in the target space by comparison with the measured value, based on past measured values ​​acquired by the acquisition unit during a period when no gas was leaking into the target space. The invention described in claim 8 is an information processing device according to claim 7, wherein the acquisition unit acquires the measured value for each of the multiple measurement points in the target space, and the setting unit sets the reference value for each measurement point based on the multiple past measured values ​​acquired by the acquisition unit for each measurement point during a period when no gas is leaking into the target space. The invention described in claim 9 is an information processing device according to claim 8, wherein the setting unit adjusts the number of data points for each of the past measurement values ​​to match the number of data points for the fewest past measurement values ​​when the number of data points for multiple past measurement values ​​are different from each other. The invention described in claim 10 is an information processing device according to claim 7, further comprising a detection unit that detects gas leakage in the target space by comparing the measured value with the reference value, wherein the setting unit modifies the reference value by using the measured value as the past measured value when the detection unit determines, by comparing the measured value with the reference value, that gas is not leaking into the target space. The invention described in claim 11 is a program that enables an information processing device to have the following functions: acquire a measured value representing the gas concentration in a target space, calculated from the received signal of light that has been scanned through the target space and passed through the target space; and set a reference value used to detect a gas leak in the target space by comparing it with the measured value, based on past measured values ​​acquired during a period when no gas was leaking into the target space. [Effects of the Invention]

[0006] According to the inventions of claims 1, 7, and 11, gas leaks in a target space can be detected more accurately compared to a case where the reference value used for detecting gas leaks in a target space is uniform regardless of past measurement values. According to the invention of claim 2, gas leakage in the target space can be detected more accurately compared to not comparing the measured value with a reference value at each measurement point. According to the invention of claim 3, gas leakage in the target space can be detected more accurately than when gas leakage is not detected by comparing the sum of measured values ​​with a threshold value. According to the invention of claim 4, gas leakage in the target space can be detected more accurately compared to the case where gas leakage is detected using the measurement value of a measurement point where the intensity of light received by the light receiving unit is less than the standard intensity. According to the invention of claim 5, compared to the case where gas leakage in the target space is detected when the number of measurement points at which the intensity of light received by the light receiving unit is equal to or greater than a standard intensity is less than a predetermined number, the output of information indicating that gas has leaked in the target space even though there is no gas leakage is suppressed. According to the invention of claim 6, compared to the case where the measurement value at a measurement point at a position where light from the optical scanning unit does not reach the reflector is used to detect gas leakage, gas leakage in the target space can be detected more accurately. According to the invention of claim 8, gas leakage in the target space can be detected more accurately compared to not setting a reference value based on multiple measurement values. According to the invention of claim 9, when the number of data points for multiple past measurement values ​​differs from each other, gas leakage in the target space can be detected more accurately compared to when the number of data points is not adjusted. According to the invention of claim 10, it is possible to revise the reference value without having to set aside a new period for acquiring new measurement values. [Brief explanation of the drawing]

[0007] [Figure 1] This diagram shows the overall configuration of the leak detection system to which this embodiment is applied. [Figure 2] This figure illustrates how the leak detection system to which this embodiment is applied is used. [Figure 3] This figure illustrates how the leak detection system to which this embodiment is applied is used. [Figure 4] This diagram illustrates the rotational operation of a detection device using a rotating platform. [Figure 5] This is a block diagram showing an example of the functional configuration of the control device to which this embodiment is applied. [Figure 6] This is a flowchart illustrating the procedure by which the control device sets the reference value. [Figure 7] This figure shows an example of a measurement value acquired by the acquisition unit in a single measurement operation. [Figure 8] This diagram illustrates the process of calculating the average value of the measurements at each measurement point. [Figure 9] This diagram illustrates the process of calculating the reference value for each measurement point. [Figure 10] This flowchart shows the procedure for the control device to set a threshold. [Figure 11] This flowchart shows the steps that the control unit executes when the leak detection system performs its monitoring operation. [Figure 12] This graph shows an example of the relationship between the sum of measurements exceeding the standard value and the threshold value. [Modes for carrying out the invention]

[0008] [Embodiment 1] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a diagram showing the overall configuration of a leakage detection system 1 to which this embodiment is applied. FIGS. 2 and 3 are diagrams showing the usage modes of the leakage detection system 1 to which this embodiment is applied. FIG. 2 is a view of the target space S for detecting gas leakage by the leakage detection system 1 as seen from directly above. FIG. 3 is a view of the target space S as seen in the horizontal direction.

[0009] The leakage detection system 1 of this embodiment emits light having a predetermined wavelength with respect to a target space S for detecting gas leakage, and scans the target space S with this light. Further, the leakage detection system 1 receives a part of the reflected light reflected in the target space S. Then, the leakage detection system 1 detects gas leakage in the target space S from the light reception result of the reflected light. Hereinafter, the gas that is the target for detecting leakage by the leakage detection system 1 may be referred to as the detection target gas. Although details will be described later, when the detection target gas exists in the target space S, a part of the light emitted by the leakage detection system 1 is absorbed by the detection target gas. The leakage detection system 1 recognizes that there is light absorption by the detection target gas from the light reception result of the light reflected in the target space S, and detects leakage of the detection target gas in the target space S.

[0010] The gases that can be detected by the leak detection system 1 include fluorocarbons, carbon monoxide, carbon dioxide, ethylene, methane, ethane, propane, isobutane, butane, propylene, ammonia, hydrogen sulfide, and hydrogen fluoride. Specific examples of fluorocarbons include difluoromethane (refrigerant code: R32), pentafluoroethane (refrigerant code: R125), 1,1,1-trifluoroethane (refrigerant code: R143a), 1,1,1,2-tetrafluoroethane (refrigerant code: R134a), 1,1-difluoroethane (refrigerant code: R152a), 2,3,3,3-tetrafluoro-1-propene (refrigerant code: R1234yf), 1,3,3,3-tetrafluoropropene (refrigerant code: R1234ze), trans-1,2-difluoroethylene (refrigerant code: HFO1132(E)), trifluoroethylene (refrigerant code: HFO1123), etc. However, the gases to be detected are not limited to these gases.

[0011] An example of a target space S for which the leak detection system 1 detects a leak of the target gas is an outdoor or indoor space in which a pipe 90 through which a gas containing the target gas flows is installed. In this case, the leak detection system 1 detects the target gas leaking from the pipe 90. In this example, the target space S is the space enclosed by the floor surface 91 on which the piping 90 is installed and the fence 92 provided around the piping 90. When viewed from above, the target space S has a rectangular shape with a long side and a short side. The fence 92 is provided so as to follow the long side and the short side of this rectangle.

[0012] Furthermore, the target space S is provided with reflectors 50 that reflect light emitted from the detection device 10 of the leak detection system 1, which will be described later. In this example, the reflectors 50 are attached to the fences 92 located on the lower and right sides of Figure 2, among the fences 92 provided on the four sides of the target space S. Also, as shown in Figure 3, the reflectors 50 are attached to the top of each fence 92.

[0013] As the reflector 50, for example, a retroreflective sheet having the property of reflecting incident light back in the direction of incidence can be used. The reflector 50 is not particularly limited as long as the required reflectance can be obtained. In this embodiment, a sheet-like reflector 50 is attached to the fence 92, but the fence 92 itself may also function as the reflector 50. Furthermore, if the target space S is outdoors, holes may be provided in the reflector 50 or the reflector 50 may be made into a louvered shape from the viewpoint of reducing wind resistance.

[0014] The leak detection system 1 includes a detection device 10 for detecting gas leaks, a turntable 20 for rotating the detection device 10, and a control device 30 for controlling the operation of the detection device 10 and the turntable 20. In the leak detection system 1, the detection device 10 is mounted on a rotating platform 20. Furthermore, in the leak detection system 1, the detection device 10 and the rotating platform 20 are installed in the upper left corner of the target space S, as shown in Figure 2. Also, as shown in Figure 3, the detection device 10 and the rotating platform 20 are installed so that their heights are approximately the same as those of the reflector 50.

[0015] The detection device 10 includes a light emitting unit 11 that emits light toward the target space S. The detection device 10 also includes a light receiving unit 12 that receives the light emitted from the light emitting unit 11 and reflected from the target space S. The detection device 10 also includes a lens 13 that focuses the light reflected from the target space S onto the light receiving unit 12. The detection device 10 integrates a light emitting unit 11, a light receiving unit 12, and a lens 13.

[0016] The light-emitting unit 11 is composed of, for example, a laser diode. The light-emitting unit 11 emits light within a predetermined wavelength range into the target space S. More specifically, the light-emitting unit 11 emits light whose wavelength is modulated by a predetermined frequency within a range that includes the absorption wavelength of the gas to be detected. In addition, the light-emitting unit 11 emits light horizontally toward the target space S.

[0017] The light-receiving unit 12 is composed of, for example, a photodiode. The light-receiving unit 12 receives a portion of the light emitted from the light-emitting unit 11 and reflected by the surfaces of reflectors 50, pipes 90, etc., provided in the target space S, via the lens 13. The light-receiving unit 12 also outputs an electrical signal corresponding to the intensity of the received light to the leak detection unit 33 of the control device 30, which will be described later. Hereafter, the electrical signal corresponding to the intensity of the light received by the light-receiving unit 12 may be referred to as the received signal. The received signal will be explained in detail later.

[0018] The lens 13 is composed of, for example, a Fresnel lens, and focuses the light (reflected light) emitted from the light-emitting unit 11 and reflected in the target space S onto the light-receiving surface of the light-receiving unit 12. In the detection device 10 of this embodiment, the light-receiving surface of the light-receiving unit 12 faces the same direction as the direction of light emission from the light-emitting unit 11.

[0019] The rotating platform 20 rotates the detection device 10 horizontally at a predetermined rotational speed around a rotation axis that extends vertically. Figure 4 illustrates the rotational movement of the detection device 10 using the turntable 20. Note that the angles shown in Figure 4 are illustrative examples and not necessarily precise. In this example, the turntable 20 performs a forward movement, rotating the detection device 10 350° clockwise from a predetermined starting point to an ending point. Following the forward movement, the turntable 20 performs a return movement, rotating the detection device 10 350° counterclockwise from the ending point to the starting point.

[0020] The speed at which the rotating platform 20 rotates the detection device 10 varies depending on the number of data points to be acquired as measured values, as described later, but for example, it can be set to 1° / second. In this case, the rotating platform 20 performs the forward movement over 350 seconds, and then performs the return movement over another 350 seconds. Furthermore, in this embodiment, after the forward and return movements are completed, the turntable 20 performs a stopping operation to stop the rotation of the detection device 10, and then performs the forward and return movements again. In other words, the turntable 20 repeatedly performs the forward movement, return movement, and stopping operation. The period for performing the stopping operation can be, for example, 40 seconds. In the following explanation, the speed at which the rotating platform 20 rotates the detection device 10 may be simply referred to as the rotational speed of the detection device 10.

[0021] In the leak detection system 1, the detection device 10 is rotated by the rotating platform 20, so that the light emitted from the light emitting section 11 of the detection device 10 is irradiated over the entire area of ​​the target space S. In the leak detection system 1, a rotating table 20 and a light-emitting unit 11 of the detection device 10 constitute an optical scanning unit that scans light of a predetermined wavelength across the target space S.

[0022] Furthermore, in the leak detection system 1, the light receiving unit 12 of the detection device 10 receives light reflected from the target space S at predetermined time intervals and outputs a light receiving signal. For example, the light receiving unit 12 receives light reflected from the target space S and outputs a light receiving signal every 0.1 seconds. And, as described above, if the rotation speed of the detection device 10 is 1° / second, the light receiving unit 12 receives light reflected from the target space S and outputs a light receiving signal every 0.1° rotation of the detection device 10.

[0023] As a result, in the leak detection system 1 of this embodiment, a measurement value representing the concentration of the target gas to be detected, calculated based on the received light signal, is acquired at 0.1° intervals centered on the detection device 10 in the target space S. In the target space S, the positions where the leak detection system 1 acquires measurement values ​​during the forward movement of the rotating platform 20 are designated as measurement point 1, measurement point 2, ..., measurement point 3500. As shown in Figure 4, measurement points 1, 2, ..., and 3500 are arranged in the target space S at 0.1° intervals in a clockwise direction around the detection device 10. Furthermore, in the target space S, the positions where the leak detection system 1 acquires measurement values ​​during the period when the rotating platform 20 is performing its return movement are defined as measurement point 3501, measurement point 3502, ..., measurement point 7000. As shown in Figure 4, measurement points 3501, 3502, ..., and 7000 are arranged in the target space S at 0.1° intervals in a counterclockwise direction around the detection device 10.

[0024] In the leak detection system 1 of this embodiment, when the rotating platform 20 performs a forward rotation operation in a clockwise direction, the light emitting unit 11 of the detection device 10 sequentially irradiates light onto measurement points 1, 2, ..., 3500 in the target space S. The light receiving unit 12 of the detection device 10 then receives the light reflected from measurement points 1, 2, ..., 3500 in the target space S and sequentially outputs the received light signals. Subsequently, as the turntable 20 rotates counterclockwise in a return motion following the forward motion, the light emitting unit 11 of the detection device 10 sequentially irradiates light onto measurement points 3501, 3502, ..., 7000 in the target space S. The light receiving unit 12 of the detection device 10 then receives the light reflected from measurement points 3501, 3502, ..., 7000 in the target space S and sequentially outputs the received light signals. In the following explanation, if measurement point 1, measurement point 2, ..., measurement point 7000 are not distinguished from each other, they may simply be referred to as "measurement point."

[0025] The control device 30 is a computer device composed of, for example, a CPU (Central Processing Unit) 30A, a ROM (Read Only Memory) 30B, and a RAM (Random Access Memory) 30C. The CPU loads various programs stored in the ROM 30B and other storage devices (not shown) into the RAM 30C and executes them, thereby realizing the various functions of the control device 30 described later. The RAM 30C is a memory used as the CPU's working memory, and the ROM 30B is a memory that stores various programs executed by the CPU 30A. The control device 30 consists of, for example, a PC (Personal Computer) or a server computer. The control device 30 is an example of an information processing device.

[0026] Figure 5 is a block diagram showing an example of the functional configuration of the control device 30 to which this embodiment is applied. The control device 30 includes an emission control unit 31 that controls the emission of light from the light emission unit 11. The control device 30 also includes an acquisition unit 32 that acquires a measured value representing the concentration of the target gas in the target space S based on the received signal output from the light receiving unit 12. The control device 30 also includes a leak determination unit 33 that determines whether the target gas is leaking in the target space S based on the measured value acquired by the acquisition unit 32. The control device 30 also includes a range setting unit 34 that sets the leak detection range for the target space S in which the leak determination unit 33 determines whether the target gas is leaking. The control device 30 also includes a reference setting unit 35 that sets a reference value used by the leak determination unit 33 to determine whether the target gas is leaking. The control device 30 also includes an output unit 36 ​​that outputs information such as whether a leak of the target gas has occurred in the target space S based on the detection result from the leak determination unit 33. Furthermore, the control device 30 includes a storage unit 37 that stores various information such as the leak detection range set in the range setting unit 34 and the reference value set by the reference setting unit 35.

[0027] The light emission control unit 31 controls the light emission unit 11 to emit light within a predetermined wavelength range. In this embodiment, the emission control unit 31 emits light that is modulated by a predetermined wavelength at a predetermined fundamental frequency, centered around a predetermined wavelength (hereinafter sometimes referred to as the center wavelength). In addition, the emission control unit 31 controls the light emission unit 11 to emit light in a wavelength range having a predetermined width above and below the predetermined wavelength. The fundamental frequency at which the emission control unit 31 modulates the light can be, for example, 10 kHz. The modulation width at which the emission control unit 31 modulates the light can be, for example, ± tens to ± hundreds of pm.

[0028] The central wavelength is determined such that the wavelength range of the light emitted from the light emission unit 11 includes the absorption peak in the optical absorption spectrum of the gas to be detected. More preferably, the emission control unit 31 emits light modulated within a wavelength range centered on the wavelength of the absorption peak in the optical absorption spectrum of the gas to be detected to the light emission unit 11. This improves the detection accuracy of the gas to be detected. It also facilitates the processing of the received light signal reflected in the target space S and received by the light receiving unit 12.

[0029] In this case, if the light-emitting unit 11 is made of a laser diode, the wavelength of the light emitted from the light-emitting unit 11 changes according to the current value supplied to the light-emitting unit 11 and the temperature of the light-emitting unit 11. The light emission control unit 31 controls the temperature of the light-emitting unit 11 and controls the current value supplied to the light-emitting unit 11 at a predetermined fundamental frequency so that the wavelength of the light emitted from the light-emitting unit 11 is within a predetermined wavelength range.

[0030] The acquisition unit 32 acquires the received light signal from the light receiving unit 12, which is the light signal of the light scanned into the target space S by the light emitting unit 11 and passed through the target space S. Then, the acquisition unit 32 obtains a measured value representing the concentration of the target gas in the target space S from the received light signal. In this embodiment, the acquisition unit 32 acquires the column density (ppm·m), which is the product of the concentration of the target gas (ppm) and the thickness D (m) of the target gas present in the target space S, as a measured value.

[0031] Specifically, as described above, the light emission unit 11 emits light (first harmonic) modulated at a predetermined frequency (e.g., 10 kHz) centered around a predetermined central wavelength, based on control by the emission control unit 31. If the target gas is present in the target section S, a portion of the light emitted from the light emission unit 11 is absorbed by the target gas. This generates light (second harmonic) with twice the frequency (e.g., 20 kHz) of the light emitted from the light emission unit 11. The light receiving unit 12 receives the first and second harmonics reflected in the target space S. The acquisition unit 32 then receives the received signals corresponding to the first and second harmonics received by the light receiving unit 12.

[0032] The acquisition unit 32 acquires the column density of the target gas in the target space S, which is an example of a measured value, based on the ratio of the first harmonic component to the second harmonic component in the received signal acquired from the light receiving unit 12. Furthermore, if, for example, the intensity of the light received by the light receiving unit 12 is weak, the proportion of noise in the received signal from the light receiving unit 12 will increase, which may cause errors in the column density acquired by the acquisition unit 32. For this reason, even if, for example, the target gas is not leaking into the target space S, the column density acquired by the acquisition unit 32 may not be zero.

[0033] In the leak detection system 1 of this embodiment, the rotating platform 20 repeatedly performs forward and return movements with a stop operation in between. As the detection device 10 rotates due to the forward and return movements in the leak detection system 1, the light receiving unit 12 performs a light receiving operation for each measurement point in the target space S and outputs a light receiving signal. The acquisition unit 32 acquires measurement values ​​for each measurement point based on the light reception signal for each measurement point output from the light receiving unit 12.

[0034] Specifically, the acquisition unit 32 acquires measurement values ​​for measurement point 1, measurement point 2, ..., measurement point 3500 based on the light receiving signal output from the light receiving unit 12 as the rotating table 20 moves forward. In addition, the acquisition unit 32 acquires a total of 3500 measurement values ​​for measurement point 1, measurement point 2, ..., measurement point 3500 as the rotating table 20 moves forward. Furthermore, the acquisition unit 32 acquires measurement values ​​for measurement points 3501, 3502, ..., and 7000 based on the light receiving signal output from the light receiving unit 12 as the turntable 20 moves back. In addition, the acquisition unit 32 acquires a total of 3500 measurement values ​​for measurement points 3501, 3502, ..., and 7000 as the turntable 20 moves back. Furthermore, the acquisition unit 32 acquires a total of 400 measurement values ​​during the 40 seconds that the rotating platform 20 is stopped.

[0035] As described above, the acquisition unit 32 of this embodiment acquires a total of 7,400 measurement values ​​while the turntable 20 performs a forward movement, a return movement, and a stop operation once. In the following description, the series of operations in which the turntable 20 performs a forward movement, a return movement, and a stop operation once, and during which the acquisition unit 32 acquires measurement values ​​at each measurement point, may be referred to as the measurement operation. As mentioned above, the rotating platform 20 rotates the detection device 10 at a predetermined rotational speed, but variations in rotational speed may occur. Therefore, the number of measurement data points acquired by the acquisition unit 32 in a single measurement operation may not be 7400.

[0036] The leak detection unit 33 determines whether or not the target gas has leaked in the target space S based on the measurement values ​​obtained by the acquisition unit 32. In the following description, the determination made by the leak detection unit 33 as whether or not the target gas has leaked in the target space S may be referred to as leak determination. In addition, the leak detection unit 33 makes a leak determination based on the measurement values ​​obtained by the acquisition unit 32 at measurement points that are included in the leak detection range set by the range setting unit 34. In other words, the leak detection unit 33 does not use the measurement values ​​of measurement points that are not included in the leak detection range for leak determination. Furthermore, the leakage determination unit 33 performs a leakage determination based on a comparison between the measurement value at the measurement point acquired by the acquisition unit 32 and the reference value and threshold value predetermined by the reference setting unit 35.

[0037] As will be explained in more detail later, the leak detection unit 33 compares the measured values ​​of the measurement points included in the leak detection range with a standard value determined for each measurement point. The leak detection unit 33 then determines that the target gas has leaked in the target space S if the sum of the measured values ​​at any of the measurement points where the measured value exceeds the standard value exceeds a threshold value predetermined by the standard setting unit 35.

[0038] Furthermore, the leakage detection unit 33 may perform leakage detection using the measured values ​​of measurement points among the multiple measurement points where the intensity of light received by the light receiving unit 12 is equal to or greater than a predetermined standard intensity. In other words, the leakage detection unit 33 does not need to use the measured values ​​of measurement points among the multiple measurement points where the intensity of light received by the light receiving unit 12 is less than the standard intensity for leakage detection. If the target space S is outdoors, the intensity of light received by the light receiving unit 12 may decrease due to environmental factors such as rain or fog. When the intensity of light received by the light receiving unit 12 is low, the proportion of noise in the received signal output from the light receiving unit 12 increases, making it easier for errors to occur in the measured values ​​calculated from the received signal. In this case, the accuracy of the leakage detection by the leakage detection unit 33 may decrease. In contrast, the leak detection unit 33 suppresses a decrease in the accuracy of leak detection by using the measured value of a measurement point where the intensity of light received by the light receiving unit 12 is equal to or greater than the standard intensity for leak detection.

[0039] Furthermore, the leakage detection unit 33 does not need to perform a leakage detection if the number of measurement points among the multiple measurement points where the intensity of light received by the light receiving unit 12 is equal to or greater than a predetermined standard intensity is less than a predetermined number. If the leak detection unit 33 does not perform a leak detection, the control device 30 outputs information indicating that an abnormality has occurred via the output unit 36. This abnormality may include, for example, water droplets or debris adhering to the light emitting unit 11 or light receiving unit 12 of the detection device 10.

[0040] The leakage detection process performed by the leakage detection unit 33 will be explained in detail with specific examples later. Furthermore, in the control device 30 of this embodiment, a detection unit is configured to acquire measurement values ​​using an acquisition unit 32 and a leak determination unit 33, and to detect gas leakage in the target space S by comparing the measurement values ​​with a predetermined reference value.

[0041] The range setting unit 34 sets the leak detection range for detecting leaks of the target gas to the target space S. The leak detection range is the range that includes measurement points for which the measurement values ​​are used in the leak determination by the leak determination unit 33. As described above, the target space S is provided with a reflector 50 that reflects the light emitted from the light emission unit 11 of the detection device 10. Here, at measurement points in the target space S where the reflector 50 is not provided, the light emitted from the light emission unit 11 is not reflected, so the intensity of the light received by the light receiving unit 12 tends to be lower compared to measurement points where the reflector 50 is provided. In this case, the ratio of noise in the received signal output from the light receiving unit 12 increases, and errors are likely to occur in the measured value calculated from the received signal. In this case, the accuracy of the leakage detection by the leakage detection unit 33 may decrease. In response, the range setting unit 34 sets the measurement points within the target space S where the reflector 50 is installed as the leak detection range. In the control device 30 of this embodiment, the leak detection range set by the range setting unit 34 is stored in the storage unit 37. In Figure 2, the area indicated by the diagonal lines is an example of the leak detection range set by the range setting unit 34.

[0042] Furthermore, the range setting unit 34 may set the leak detection range according to the arrangement of pipes 90, etc., in the target space S. If pipes 90 are installed between the detection device 10 and the reflector 50 in the target space S, the light emitted from the light emitting unit 11 may hit the pipes 90 and not reach the reflector 50. In this case, the intensity of the light received by the light receiving unit 12 will decrease, which may reduce the accuracy of the leak detection by the leak determination unit 33. Therefore, the range setting unit 34 may exclude from the leak detection range any measurement points in the target space S where a reflector 50 is installed, provided that a pipe 90 or the like is installed between the detection device 10 and the reflector 50.

[0043] The range setting unit 34 can set a leak detection range in the target space S based on a user's designation, such as the administrator of the leak detection system 1. Furthermore, the user determines the range to be set as the leak detection range based on, for example, a floor plan of the target space S. The user can then specify the range to be set as the leak detection range using an input device (not shown) or the like. Furthermore, the range setting unit 34 may set the leak detection range based on the light reception result by the light receiving unit 12 when the light emitting unit 11 of the detection device 10 irradiates the target space S with light. In addition, when the target gas to be detected is not leaking into the target space S and the light emitting unit 11 irradiates the target space S with light, the range setting unit 34 can set the leak detection range as the measurement point where the light intensity of the light received by the light receiving unit 12 is greater than a predetermined intensity.

[0044] The reference setting unit 35 sets the reference value and threshold used by the leak determination unit 33 for leak determination. The reference setting unit 35 sets the reference value and threshold according to past measurement values ​​acquired by the acquisition unit 32 during periods when the target gas was not leaking into the target space S. Here, "past" refers to the period before the leak determination unit 33 made a determination as to whether or not the target gas had leaked. In the control device 30 of this embodiment, the reference value and threshold value set by the reference setting unit 35 are stored in the storage unit 37. The setting of the reference value and threshold value by the reference setting unit 35 will be described in detail later.

[0045] The output unit 36 ​​outputs information indicating that the target gas has leaked in the target space S, according to the leak determination result from the leak determination unit 33. The output mode of the output unit 36 ​​is not particularly limited. For example, the output unit 36 ​​outputs information indicating that the target gas has leaked in the target space S to a computer device such as a PC or tablet terminal, as an example of an output device (not shown). The output unit 36 ​​then displays a message indicating that the target gas has leaked on these display screens. Alternatively, the output unit 36 ​​may indicate that the target gas has leaked by illuminating the detection device 10 or a warning lamp located outside the detection device 10, as an example of an output device. Furthermore, the output unit 36 ​​may also indicate that the target gas has leaked by voice through the detection device 10 or a speaker located outside the detection device 10, as an example of an output device.

[0046] Next, the procedure for detecting a leak of the target gas in the target space S using the leak detection system 1 of this embodiment will be described. When detecting a leak of a target gas using the leak detection system 1, first, the user of the leak detection system 1 installs the equipment of the leak detection system 1 in the target space S. Specifically, the user installs the detection device 10 and the rotating platform 20 at predetermined locations in the target space S. In addition, the user installs the reflector 50 in the target space S at a location where light emitted from the light emission unit 11 of the detection device 10 illuminates.

[0047] Next, the leak detection system 1 sets a leak detection range for detecting leaks of the target gas in the target space S, based on the positional relationship between the detection device 10 and the reflector 50 installed in the target space S. For example, the leak detection system 1 sets the measurement points in the target space S where the reflector 50 is located as the leak detection range. In this case, the range setting unit 34 of the control device 30 sets the leak detection range based on the range specified by the user.

[0048] Next, the leak detection system 1 sets reference values ​​and thresholds used for detecting leaks of the target gas. Specifically, the leak detection system 1 sets the reference values ​​and thresholds using the results of scanning the target space S with light using the light emission unit 11 of the detection device 10 during periods when the target gas is not leaking into the target space S. Specifically, the leak detection system 1 performs a measurement operation when the target gas is not leaking into the target space S, and the acquisition unit 32 of the control device 30 acquires the measurement value at each measurement point. As will be described in detail later, the leak detection system 1 of this embodiment performs the measurement operation multiple times and acquires multiple measurement values ​​at each measurement point. Then, the reference setting unit 35 of the control device 30 sets a reference value for each measurement point based on the multiple measurement values ​​that have been acquired.

[0049] Furthermore, the leak detection system 1 sets a reference value for each measurement point and then performs the measurement operation multiple times. The acquisition unit 32 of the control device 30 acquires multiple measurement values ​​for each measurement point. The reference setting unit 35 of the control device 30 then sets a threshold value based on the relationship between the acquired measurement values ​​for each measurement point and the reference value set for each measurement point.

[0050] Next, the leak detection system 1 performs a monitoring operation to monitor for leaks of the target gas in the target space S based on leak determination by the leak determination unit 33. Specifically, the detection device 10 and the rotating platform 20 are used to scan the light emitted from the light emitting unit 11 across each measurement point in the target space S. Then, based on the received light signals obtained by the light receiving unit 12 from the light at each measurement point, the acquisition unit 32 of the control device 30 acquires the measured values ​​at each measurement point. Then, the leak determination unit 33 of the control device 30 makes a leak determination based on a comparison between the measured values ​​acquired at each measurement point and the reference values ​​and thresholds predetermined by the reference setting unit 35.

[0051] If the leak detection unit 33 determines that the target gas has leaked into the target space S, the output unit 36 ​​outputs information indicating that the target gas has leaked into the target space S. The leak detection system 1 continuously performs monitoring operations to detect leaks of the target gas in the target space S described above.

[0052] Next, we will explain in detail the process by which the control device 30 of the leak detection system 1 sets the reference value used by the leak determination unit 33 for leak determination. Figure 6 is a flowchart showing the procedure for the control device 30 to set a reference value.

[0053] The leak detection system 1 performs the measurement operation when no target gas is leaking into the target space S, and the acquisition unit 32 of the control device 30 acquires the measured values ​​at each measurement point (step 101). Figure 7 shows an example of a measurement value acquired by the acquisition unit 32 in a single measurement operation. In Figure 7, the column density (ppm·m) of the gas to be detected is shown as the measurement value. Furthermore, in Figure 7, for the sake of simplicity, only a portion of the measurement values ​​at measurement points 1, ..., and 7000 acquired by the acquisition unit 32 during the forward and return movements of the turntable 20 are shown. Also, the measurement values ​​acquired by the acquisition unit 32 while the turntable 20 is stopped are not used for setting the reference value and are therefore omitted from Figure 7.

[0054] As described above, the acquisition unit 32 acquires a total of 3,500 measurement values ​​from measurement point 1, measurement point 2, ..., measurement point 3500 as the turntable 20 moves forward. In addition, the acquisition unit 32 acquires a total of 3,500 measurement values ​​from measurement point 3501, measurement point 3502, ..., measurement point 7000 as the turntable 20 moves back. Furthermore, the acquisition unit 32 acquires a total of 400 measurement values ​​while the turntable 20 is stopped. In addition, the acquisition unit 32 acquires a total of 7,400 measurement values ​​in one measurement operation. However, as described above, due to variations in the rotation speed of the turntable 20, the number of measurement data acquired by the acquisition unit 32 in one measurement operation may not necessarily be 7,400.

[0055] The leak detection system 1 repeatedly performs measurement operations, and the acquisition unit 32 repeatedly acquires the measurement values ​​at each measurement point. The acquisition unit 32 acquires the measurement values ​​at each measurement point a predetermined number of times. In this example, the acquisition unit 32 acquires the measurement values ​​at each measurement point a total of 56 times, as an example of a predetermined number.

[0056] Next, the control device 30 adjusts the number of data points for the 56 acquired measurement values ​​using the reference setting unit 35 (step 102). As described above, the number of measurement data points acquired by the acquisition unit 32 in a single measurement operation is not necessarily 7400, and may vary from measurement to measurement. If the number of measurement data points varies from measurement to measurement, it may cause problems when setting the threshold, as described later. For this reason, the reference setting unit 35 in this embodiment adjusts the data points so that they become equal if the number of measurement data points for 56 measurements varies from measurement to measurement.

[0057] First, the reference setting unit 35 rearranges the order of the measurements from each measurement run so that the measurement from measurement point 1 is at the beginning and the measurement taken during the stopping operation is at the end. In other words, the reference setting unit 35 rearranges the measurements from each measurement run in the order of measurement from measurement point 1, measurement from measurement point 2, ..., measurement from measurement point 7000, and measurement taken during the stopping operation. Next, the reference setting unit 35 adjusts the number of data points in each measurement to match the measurement with the fewest data points among the 56 measurement values ​​that have been rearranged. In addition, the reference setting unit 35 truncates the measurement values ​​from the end of each measurement by the difference in the number of data points between it and the measurement with the fewest data points, so that the number of data points is equal to that of the measurement with the fewest data points. This makes the number of data points for all 56 measurement values ​​equal. For example, if the number of data points for the measurement with the fewest data points is 7400-α, the reference setting unit 35 adjusts the number of data points for all 56 measurement values ​​to 7400-α.

[0058] Next, the control device 30, using the reference setting unit 35, calculates the average value of 56 measurements for each of the measurement points 1 to 7000, and obtains the average shape of the measurement points 1 to 7000 (step 103). Figure 8 illustrates the process of calculating the average value of the measurements at each measurement point. The reference setting unit 35 calculates the average value of the measurements obtained from 56 measurement operations for measurement point 1. The reference setting unit 35 similarly calculates the average value of the measurements obtained from 56 measurement operations for measurement points 2, 3, ..., and 7000. The reference setting unit 35 then combines the calculated average values ​​of the measurements from measurement points 1 to 7000 to form the average shape. In the following explanation, the average value of the measurements for each measurement point may be simply referred to as the average value for each measurement point.

[0059] Next, the control device 30, specifically the reference setting unit 35, calculates a reference value for each measurement point from the average value of each measurement point in the average shape obtained in step 103 (step 104). Figure 9 illustrates the process for calculating the reference value for each measurement point. The reference setting unit 35 calculates the variance and standard deviation of each measurement point in the average shape of the measurements obtained in step 103. Then, the reference setting unit 35 sets the value obtained by adding 2σ to the average value of each measurement point as the reference value for each measurement point.

[0060] Through the above process, the reference setting unit 35 can set reference values ​​for each measurement point used for leakage determination by the leakage determination unit 33. In the example described above, the reference setting unit 35 sets the reference value for each measurement point using a total of 56 measurement values ​​as multiple measurement values, but it is not limited to 56 values.

[0061] Next, we will explain in detail the process of setting the threshold used for leak detection by the control device 30 and the leak determination unit 33 of the leak detection system 1. Figure 10 is a flowchart showing the procedure for the control device 30 to set a threshold. The leak detection system 1 sets a reference value for each measurement point using the reference setting unit 35, and then performs the measurement operation again when no target gas is leaking into the target space S. Then, the control device 30 acquires the measured values ​​at each measurement point using the acquisition unit 32 (step 201).

[0062] Next, the control device 30 adjusts the number of measurement data points acquired in step 201 using the reference setting unit 35 (step 202). More specifically, the reference setting unit 35, similar to step 102 described above, rearranges the order of the acquired measurements so that the measurement at measurement point 1 is at the beginning and the measurement taken during the stopping operation is at the end. Next, the reference setting unit 35 truncates the acquired measurement values ​​from the end so that the number of acquired measurement values ​​equals the number of data adjusted in step 102. For example, if the number of data values ​​was adjusted to 7400-α in step 102, then in step 202, the measurement values ​​are similarly truncated from the end so that the number of data values ​​becomes 7400-α.

[0063] Next, the control device 30 compares the measured values ​​of each measurement point after the reference setting unit 35 has adjusted the number of data points with the reference values ​​of each measurement point set in steps 101 to 104, and calculates a preliminary value to be used for calculating the threshold (step 203). Specifically, the reference setting unit 35 compares the measured value at measurement point 1 with the reference value at measurement point 1. Similarly, the reference setting unit 35 compares the measured values ​​at measurement points 2, 3, ..., 7000 with the reference values ​​at measurement points 2, 3, ..., 7000, respectively. Next, the reference setting unit 35 accumulates the measured values ​​at each measurement point that exceed the reference value. The reference setting unit 35 then uses the sum of the measured values ​​that exceed the reference value as the reserve value.

[0064] Next, the control device 30 determines whether the reference setting unit 35 has calculated the reserve value a predetermined number of times. In this example, the reference setting unit 35 determines whether it has calculated the reserve value 56 times (step 204). If the calculation of the preliminary value has not been performed 56 times (NO in step 204), the control device 30 returns to step 201 and continues processing.

[0065] If the preliminary value calculation is performed 56 times (YES in step 204), the control device 30 has the reference setting unit 35 calculate a threshold value used by the leak detection unit 33 for leak detection from the 56 preliminary values ​​(step 205). Specifically, the reference setting unit 35 calculates the average value of 56 preliminary values. The reference setting unit 35 also calculates the variance and standard deviation of the 56 preliminary values ​​from the average value of the 56 preliminary values. Then, the reference setting unit 35 sets a threshold value obtained by adding 2σ to the average value of the 56 preliminary values.

[0066] Furthermore, the reference setting unit 35 may set a predetermined value as the threshold if the value obtained by adding 2σ to the average of 56 preliminary values ​​is less than a predetermined value. For example, the reference setting unit 35 may set the threshold to 500 if the value obtained by adding 2σ to the average of 56 preliminary values ​​is less than 500.

[0067] Through the above process, the reference setting unit 35 can set the threshold used for leakage determination by the leakage determination unit 33. In the example described above, the reference setting unit 35 sets the threshold using a total of 56 reserve values ​​as multiple reserve values, but it is not limited to 56 values.

[0068] Next, we will explain in detail the monitoring operation in which the leak detection system 1 monitors for leaks of the target gas in the target space S based on leak determination by the leak determination unit 33 of the control device 30. Figure 11 is a flowchart showing the steps of the process that the control device 30 executes when the leak detection system 1 performs a monitoring operation. The process shown in Figure 11 is repeatedly performed at predetermined time intervals by the control device 30 during the period when the leak detection system 1 is performing monitoring operations.

[0069] The leak detection system performs a measurement operation and acquires the measurement values ​​at each measurement point using the acquisition unit 32 (step 301). Next, the control device 30 adjusts the number of measurement data points obtained in step 301 by the leak determination unit 33 (step 302). More specifically, the leak detection unit 33, similar to steps 102 and 202 described above, rearranges the order of the acquired measurements so that the measurement at measurement point 1 is at the beginning and the measurement taken during the stop operation is at the end. Next, the leakage detection unit 33 truncates the acquired measurement values ​​from the end so that the number of acquired measurement values ​​equals the number of data adjusted in steps 101 and 202. For example, if the number of data values ​​was adjusted to 7400-α in steps 101 and 202, then in step 302, the measurement values ​​are similarly truncated from the end so that the number of data values ​​becomes 7400-α.

[0070] Next, the control device 30 compares the measured values ​​at each measurement point, after the leakage determination unit 33 has adjusted the number of data points, with the reference values ​​for each measurement point set by the reference setting unit 35. Then, it calculates the sum by accumulating the measured values ​​at each measurement point that exceed the reference value (step 303). Specifically, the leak detection unit 33 compares the measured value at measurement point 1 with the reference value at measurement point 1. Similarly, the leak detection unit 33 compares the measured values ​​at measurement points 2, 3, ..., 7000 with the reference values ​​at measurement points 2, 3, ..., 7000. Then, the leak detection unit 33 accumulates the measured values ​​at each measurement point that exceed the reference value and calculates the sum. In the following explanation, the sum of measured values ​​that exceed the reference value calculated in step 303 may be simply referred to as the sum of measured values.

[0071] Here, as described above, the leakage detection unit 33 may calculate the sum of the measured values ​​using only the measured values ​​from the measurement points where the intensity of light received by the light receiving unit is equal to or greater than the standard intensity among the multiple measurement points. In addition, the leakage detection unit 33 may compare the measured values ​​from the measurement points where the intensity of light received by the light receiving unit is equal to or greater than the standard intensity with the standard value and calculate the sum of the measured values ​​that exceed the standard value. Furthermore, the leakage detection unit 33 does not need to calculate the sum of the measured values ​​if the number of measurement points among the multiple measurement points where the intensity of light received by the light receiving unit 12 is equal to or greater than a predetermined standard intensity is less than a predetermined number. In this case, the control device 30 outputs information indicating that an abnormality has occurred via the output unit 36. After that, the control device 30 returns to step 301 and continues the monitoring operation.

[0072] Next, the control device 30 determines whether the total of the measured values ​​that exceeded the reference value has exceeded the threshold set by the reference setting unit 35 (step 304). If the sum of the measured values ​​does not exceed the threshold (NO in step 304), the control device 30 returns to step 301 and continues the monitoring operation.

[0073] If the sum of the measured values ​​exceeds the threshold (YES in step 304), the control device 30 determines whether the sum of the measured values ​​has exceeded the threshold twice in a row (step 305). In step 305, the leakage detection unit 33 can determine, for example, whether the sum of the measured values ​​has exceeded the threshold twice in a row by turning a flag ON or OFF. Specifically, in step 304, the leakage detection unit 33 turns the flag ON if it determines that the sum of the measured values ​​has exceeded the threshold. Also, in step 304, the leakage detection unit 33 turns the flag OFF if it determines that the sum of the measured values ​​has not exceeded the threshold.

[0074] Subsequently, in step 304 of the monitoring operation, if the flag was ON when it was determined that the sum of the measured values ​​exceeded the threshold, the leakage detection unit 33 determines in step 305 that the sum of the measured values ​​exceeded the threshold twice in a row. On the other hand, if the flag was OFF when the system determined in step 304 that the sum of the measured values ​​exceeded the threshold, the leakage detection unit 33 determined in step 305 that the sum of the measured values ​​had not exceeded the threshold for two consecutive times. In other words, the leakage detection unit 33 determined that this was the first time the sum of the measured values ​​exceeded the threshold.

[0075] If the sum of the measured values ​​exceeds the threshold for the first time (NO in step 305), the control device 30 returns to step 301 and continues the monitoring operation. If the sum of the measured values ​​exceeds the threshold for two consecutive times (YES in step 305), the control device 30 determines that the leak determination unit 33 is leaking the target gas in the target space S (step 306). Next, the control device 30 outputs information from its output unit 36 ​​indicating that the target gas has leaked in the target space S (step 307). Subsequently, the control device 30 returns to step 301 and continues the monitoring operation.

[0076] Figure 12 is a graph showing an example of the relationship between the sum of measurements exceeding the standard value and the threshold value. In the example shown in Figure 12, the relationship between the sum of measurements exceeding the standard value and the threshold value is shown when the detection device 10 performs measurement operations and the control device 30 performs leak detection at predetermined time intervals. The vertical axis of Figure 12 represents the sum of measurements exceeding the standard value, calculated in step 303 described above. The horizontal axis of Figure 12 represents the number of times the detection device 10 performed measurement operations and the control device 30 performed leak detection. In this example, the threshold value used for leak detection by the leak detection unit 33 is set to 500 and is shown in Figure 12.

[0077] In the example shown in Figure 12, the sum of the measured values ​​exceeding the reference value is 0 up to the 8th measurement operation. Furthermore, in the 9th measurement operation, the sum of the measured values ​​exceeding the reference value is 285. Therefore, the leak detection unit 33 determines in step 304 that the sum of the measured values ​​exceeding the reference value does not exceed the threshold up to the 9th measurement operation.

[0078] Furthermore, in the 10th measurement operation, the sum of the measured values ​​that exceeded the reference value is 2120. Therefore, in the 10th measurement operation, the leak detection unit 33 determines in step 304 that the sum of the measured values ​​that exceeded the reference value exceeds the threshold. However, although the 10th measurement operation is determined to have a sum of measured values ​​that exceeds the threshold, it is the first time, so the leak detection unit 33 does not determine that the target gas is leaking in the target space S. In this case, the output unit 36 ​​does not output any information indicating that the target gas is leaking in the target space S.

[0079] Furthermore, in the 11th measurement operation, the sum of the measured values ​​that exceeded the standard value is 925. Therefore, the leak detection unit 33 determines that in the 11th measurement operation, the sum of the measured values ​​that exceeded the standard value in step 304 exceeds the threshold. Since the sum of the measured values ​​has exceeded the threshold for two consecutive measurements in the 10th and 11th measurement operations, the leak detection unit 33 determines that the target gas is leaking in the target space S. In this case, the output unit 36 ​​outputs information indicating that the target gas is leaking in the target space S.

[0080] In the subsequent 12th measurement operation, the sum of the measured values ​​that exceeded the reference value is 0. Therefore, the leak detection unit 33 determines that in the 12th measurement operation, the sum of the measured values ​​that exceeded the reference value in step 304 does not exceed the threshold. In this case, the output unit 36, which outputs information indicating that the target gas has leaked in the target space S, is canceled.

[0081] As described above, the leak detection system 1 of this embodiment scans the target space S with light of a predetermined wavelength using the detection device 10 and the rotating table 20. The control device 30 obtains a measured value representing the concentration of the target gas in the target space S from the received signal obtained by the light receiving unit 12 from the light that has passed through the target space S. The control device 30 then detects the leakage of the target gas in the target space S by comparing the measured value with a predetermined reference value.

[0082] When scanning light through the target space S and acquiring measurement values ​​sequentially, the magnitude of noise included in the measurement values ​​may differ depending on the arrangement of the detection device 10 and reflector 50, as well as differences in their positions within the target space S. In this case, if a uniform reference value is set for detecting gas leaks in the target space S, it may not be possible to accurately detect gas leaks. In contrast, in the leak detection system 1 of this embodiment, the control device 30 determines a reference value based on past measurement values ​​acquired during periods when the target gas was not leaking into the target space S. This allows for more accurate detection of leaks of the target gas in the target space S compared to a case where the reference value is uniformly determined regardless of past measurement values.

[0083] In the embodiment described above, the control device 30 sets the reference value and threshold value using the measured values ​​acquired during the period after the leak detection system 1 is installed in the target space S but before the monitoring operation is started, which is the period during which the target gas is not leaking into the target space S. However, the period during which the measured values ​​used to set the reference value and threshold value are acquired, which is the period during which the target gas is not leaking into the target space S, is not limited to this.

[0084] For example, the control device 30 may set reference values ​​and thresholds using measurement values ​​acquired during the monitoring period. Specifically, the control device 30 may set reference values ​​and thresholds using measurement values ​​acquired during the period in which the leak determination unit 33 determines that the target gas is not leaking into the target space S. Alternatively, after setting the reference values ​​and thresholds, the control device 30 may modify the reference values ​​and thresholds using measurement values ​​acquired during the period in which it is determined that the target gas is not leaking into the target space S. In this case, the control device 30 can set reference values ​​and thresholds without having to set aside a new period for stopping the monitoring operation by the leak detection system 1 and acquiring measurement values.

[0085] Although embodiments of the present invention have been described above, the present invention is not limited to these embodiments. Various modifications and combinations are permitted as long as they do not contradict the spirit of the present invention. [Explanation of symbols]

[0086] 1... Leak detection system, 10... Detection device, 11... Light emitter, 12... Light receiver, 13... Lens, 20... Rotating platform, 30... Control device, 31... Emission control unit, 32... Acquisition unit, 33... Leak determination unit, 34... Range setting unit, 35... Reference setting unit, 36... Output unit, 50... Reflector

Claims

1. A light scanning unit scans the target space for detecting gas leaks with light of a predetermined wavelength, A light receiving unit that receives light that has passed through the aforementioned target space and outputs a light receiving signal, The system includes a detection unit that obtains a measured value representing the gas concentration in the target space from the light-receiving signal and detects gas leakage in the target space by comparing the measured value with a predetermined reference value. The aforementioned reference value is determined according to past measurement values ​​obtained by the detection unit during a period when no gas is leaking into the target space, by scanning the target space with light using the optical scanning unit.

2. The optical scanning unit sequentially irradiates light onto a plurality of measurement points in the target space, The light receiving unit outputs the light receiving signal for each of the measurement points, The detection unit compares the measured value obtained for each measurement point with the reference value determined for each measurement point based on past measured values. The leak detection system according to claim 1.

3. The leak detection system according to claim 2, wherein the detection unit outputs information indicating that gas has leaked when the sum of the measured values ​​exceeds a predetermined threshold for any of the multiple measurement points where the measured value exceeds the reference value.

4. The leak detection system according to claim 2, wherein the detection unit detects gas leakage in the target space using the measured value of a measurement point among a plurality of measurement points where the intensity of light received by the light receiving unit is equal to or greater than a predetermined reference intensity.

5. The leak detection system according to claim 4, wherein the detection unit outputs information indicating that an abnormality has occurred without detecting a gas leak in the target space if the number of measurement points among the plurality of measurement points in which the intensity of light received by the light receiving unit is equal to or greater than the reference intensity is less than a predetermined number.

6. The aforementioned target space is provided with a reflector that reflects light from the optical scanning unit, The light receiving unit receives light emitted from the optical scanning unit and reflected by the reflector. The detection unit shall not use the measured values ​​of any of the multiple measurement points at which the light from the optical scanning unit does not reach the reflector for detecting gas leakage in the target space. The leak detection system according to claim 2.

7. An acquisition unit that scans a target space for detecting a gas leak and acquires a measured value representing the gas concentration in the target space calculated from the received signal of light that has passed through the target space, A setting unit sets a reference value used to detect gas leakage in the target space by comparison with the aforementioned measurement value, based on past measurement values ​​acquired by the acquisition unit during a period when no gas was leaking into the target space. An information processing device equipped with the following features.

8. The acquisition unit acquires the measured value for each of the multiple measurement points in the target space. The setting unit sets the reference value for each measurement point based on multiple past measurement values ​​acquired by the acquisition unit for each measurement point during periods when no gas is leaking into the target space. The information processing apparatus according to claim 7.

9. The information processing apparatus according to claim 8, wherein the setting unit adjusts the number of data points for each of the past measurement values ​​to match the number of data points for the fewest past measurement values ​​when the number of data points for multiple past measurement values ​​differs from one another.

10. The system further includes a detection unit that detects gas leakage in the target space by comparing the measured value with the reference value. The setting unit modifies the reference value by using the measured value as the past measured value when the detection unit determines, by comparing the measured value with the reference value, that gas is not leaking into the target space. The information processing apparatus according to claim 7.

11. For information processing equipment, A function to acquire a measured value representing the gas concentration in a target space, calculated from the light received signal of light that has been scanned through the target space and passed through the target space, and A function to set a reference value used to detect gas leakage in the target space by comparison with the aforementioned measurement value, based on past measurement values ​​obtained during a period when no gas was leaking into the target space. A program that makes this possible.

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