JP2021060377A - Gas leakage detection system and method - Google Patents

Abstract

To provide a gas leakage detection system and method capable of detecting gas leakage in a wide range and accurately estimating an existence range and a leakage place of methane gas.SOLUTION: A gas leakage detection system 1 is equipped with a gas detection device 2, and an existence range computing portion 33. The gas detection device 2 is equipped with a gas sensor 21 that emits detection light L1 to detect the leakage of methane gas on an optical path to a reflection surface R, a distance sensor 22 that emits measurement light L3 to measure a distance from the gas sensor 21 to the reflection right R, and a scanning mechanism 23 that can scan the detection light L1 of the gas sensor 21 and the measurement light L3 of the distance sensor 22 in a vertical direction or a horizontal direction. The existence range computing portion 33 limits an existence range of methane gas in a depth direction of the optical path and estimates a leakage place of that, on the basis of a range where the gas sensor 21 at each reference point detects the leakage of methane gas, when the gas detection device 2 performs measurement at a different reference point.SELECTED DRAWING: Figure 1

Description

The present invention relates to a gas leak detection system and method for detecting a leak location of methane gas from a pipe or the like.

In recent years, a laser type methane gas detector has been known as a device for detecting leakage of methane gas in an LNG (Liquid Natural Gas) production plant or the like.

Such a methane gas detector includes an absorption band that absorbs light of a specific wavelength in response to the rotation of molecules, vibrations between constituent atoms, etc. (for example, in the case of methane gas, 1.7 μm, 3.3 μm, 7. Utilizing the existence of 7 μm, etc.), the wavelength-modulated laser light (detection light) from the semiconductor laser in the light source section is passed through the atmosphere of methane gas, and the transmitted light is received by the photodetector in the light receiving section. It is known to measure the cumulative concentration of methane gas on the optical path from a signal and detect the leakage of methane gas.

However, the range in which the methane gas detector as described above can detect a gas leak is only on the optical path of the detection light, and when the gas leak is detected in a wide range, the worker determines the direction of the detection light of the methane gas detector. I had to change it little by little.

Further, the methane gas detector detects the cumulative concentration of methane gas existing in the optical path of the detection light, and cannot narrow down the existence range of methane gas in the depth direction of the optical path of the detection light. Therefore, when methane gas is diffused around a pipe or the like, it may be difficult to contribute to the identification of the leak source because the gas leak is detected in an excessively wide range including the leak source.

Therefore, there arises a technical problem to be solved in order to be able to detect a wide range of gas leaks and to accurately identify the range in which methane gas leaks, and an object of the present invention is to solve this problem. ..

In order to achieve the above object, the gas leak detection system according to the present invention is a gas leak detection system that detects the leakage of methane gas from the measurement target, and irradiates the detection light toward the measurement target to reflect the reflective surface. A laser type gas sensor that detects leakage of methane gas on the optical path up to, a distance sensor that irradiates the measurement target with distance measurement light and measures the distance from the gas sensor to the reflection surface, and detection of the gas sensor. When a gas detection device equipped with a scanning mechanism capable of scanning light and distance measurement light of the distance sensor in the vertical direction or the horizontal direction and the gas detection device perform measurement at different reference points, each reference point A computing device that limits the existence range of methane gas in the depth direction of the optical path based on the range in which the gas sensor detects the leakage of methane gas.

According to this configuration, gas leakage can be detected over a wide range by scanning the gas sensor and the distance sensor in the vertical or horizontal direction using the scanning mechanism, and further, the measurement of methane gas at each reference point can be performed. By extracting the region where the leak detected range overlaps, the existing range of the methane gas can be narrowed down in the depth direction of the optical path of the detected light. If the 3D data of the measurement target is known, only the measurement by the gas sensor is performed at each reference point, and then the known 3D data of the measurement target, the azimuth and elevation angles of the scanning mechanism, and the gas detection. By identifying the range where the leakage of methane gas is detected based on the reference point (coordinates) where the device is installed, and extracting the range where the range where the leakage of methane gas is detected overlaps in the measurement at each reference point, the methane gas The existence range can be narrowed down in the depth direction of the optical path of the detection light.

Further, in the gas leak detection system according to the present invention, the calculation device calculates the three-dimensional coordinates of the measurement target based on the distance from the gas sensor to the reflection surface measured by the distance sensor, and the measurement target 3 It is preferable to estimate the location where the methane gas is leaking based on the dimensional coordinates.

According to this configuration, the three-dimensional coordinates of the reflecting surface are calculated based on the distance data measured by the distance sensor, the azimuth and elevation angles of the scanning mechanism, and the reference point (coordinates) in which the gas detection device is installed. The source of methane gas leakage can be estimated based on the three-dimensional coordinates of the above and the existence range of methane gas limited by the depth direction of the optical path.

Further, in the gas leak detection system according to the present invention, it is preferable that the scanning mechanism is a pan head on which the gas sensor and the distance sensor are mounted.

According to this configuration, by operating the pan head, the gas sensor and the distance sensor can be integrally and accurately scanned in the vertical and horizontal directions.

Further, in the gas leak detection system according to the present invention, it is preferable that the scanning mechanism is a rotating mirror that scans the detection light of the gas sensor and the distance measurement light of the distance sensor.

According to this configuration, the rotating mirror operates the pan head, so that the detection light of the gas sensor and the distance measurement light of the distance sensor can be accurately scanned in the vertical direction and the horizontal direction.

Further, in order to achieve the above object, the gas leak detection system according to the present invention is a gas leak detection system that detects leakage of methane gas from a measurement target, and irradiates the measurement target with detection light. A gas detection device including a laser-type gas sensor that detects leakage of methane gas on the optical path to the reflection surface, and a scanning mechanism that can scan the detection light of the gas sensor in the vertical or horizontal direction, and the gas detection device. A computing device that limits the existence range of methane gas in the depth direction of the optical path based on the range in which the gas sensor detects the leakage of methane gas at each reference point when the measurement is performed at different reference points. There is.

According to this configuration, by scanning the gas sensor in the vertical or horizontal direction using the scanning mechanism, gas leakage can be detected over a wide range, and further, methane gas leakage can be detected by measurement at each reference point. By extracting the region where the overlapped ranges are extracted, the existing range of methane gas can be narrowed down in the depth direction of the optical path of the detection light.

Further, the gas leak detection system according to the present invention further includes a storage unit in which the three-dimensional coordinates of the measurement target are stored, and the arithmetic unit leaks the methane gas based on the three-dimensional coordinates of the measurement target. It is preferable to estimate the location where the

According to this configuration, leakage of methane gas is detected based on the three-dimensional data of the measurement target stored in advance in the storage unit, the azimuth and elevation angles of the scanning mechanism, and the reference point (coordinates) in which the gas detection device is installed. By specifying the range and extracting the range where the range where the leakage of methane gas is detected by the measurement at each reference point overlaps, the existing range of methane gas can be narrowed down in the depth direction of the optical path of the detected light. The source of methane gas leakage can be estimated based on the three-dimensional coordinates of the measurement target stored in advance in the storage unit and the existence range of methane gas limited in the depth direction of the optical path.

Further, in order to achieve the above object, the gas leak detection method according to the present invention is a gas leak detection method for detecting the leakage of methane gas from the measurement target, and scans the laser type gas sensor in the vertical direction or the horizontal direction. While doing so, the detection light is irradiated toward the measurement target to detect the leakage of methane gas on the optical path to the reflection surface, and the distance sensor is scanned following the gas sensor to measure the distance toward the measurement target. When the distance from the gas sensor to the reflective surface is measured by irradiating light and the gas sensor and the distance sensor measure at different reference points, the range in which the gas sensor detects the leakage of methane gas at each reference point. Based on this, the range of existence of the methane gas is limited in the depth direction of the optical path.

According to this configuration, gas leakage can be detected over a wide range by scanning the gas sensor and the distance sensor in the vertical or horizontal direction using the scanning mechanism, and further, the measurement of methane gas at each reference point can be performed. By extracting the region where the leak detected range overlaps, the existing range of the methane gas can be narrowed down in the depth direction of the optical path of the detected light.

Further, in order to achieve the above object, the gas leak detection method according to the present invention is a gas leak detection method for detecting the leakage of methane gas from a measurement target, and scans a laser type gas sensor in the vertical direction or the horizontal direction. When the gas sensor detects the leakage of methane gas on the optical path to the reflection surface by irradiating the detection light toward the measurement target and the gas sensor measures at different reference points, the gas sensor at each reference point will perform the measurement. Based on the range in which the leakage of methane gas is detected, the range of existence of methane gas is limited in the depth direction of the optical path.

According to this configuration, by scanning the gas sensor in the vertical or horizontal direction using the scanning mechanism, gas leakage can be detected over a wide range, and further, methane gas leakage can be detected by measurement at each reference point. By extracting the region where the overlapped ranges are extracted, the existing range of methane gas can be narrowed down in the depth direction of the optical path of the detection light.

According to the present invention, by scanning the gas sensor and the distance sensor in the vertical direction or the horizontal direction using the scanning mechanism, gas leakage can be detected over a wide range, and further, methane gas can be measured at each reference point. By extracting the region where the leak detected range overlaps, the existing range of the methane gas can be narrowed down in the depth direction of the optical path of the detected light.

The schematic diagram which shows the structure of the gas leak detection system which concerns on one Embodiment of this invention. The schematic diagram which shows the installation position of the gas detection device at the time of detecting a gas leak such as a pipe of a plant. The figure which shows the state of identifying the gas leak source.

An embodiment of the present invention will be described with reference to the drawings. In the following, when referring to the number, numerical value, quantity, range, etc. of components, it is limited to the specific number unless it is clearly stated or in principle it is clearly limited to the specific number. It is not a thing, and it may be more than or less than a specific number.

In addition, when referring to the shape and positional relationship of components, etc., unless otherwise specified or when it is considered that this is not the case in principle, those that are substantially similar to or similar to the shape, etc. shall be used. Including.

FIG. 1 is a diagram showing a gas leak detection system 1 according to the present invention. The gas leak detection system 1 detects a leak of methane gas in a measurement target such as a pipe of an LNG (Liquid Natural Gas) production plant. Needless to say, the facility to which the gas leak detection system 1 is applied is not limited to the LNG production plant. The gas leak detection system 1 includes a plurality of gas detection devices 2 and a control device 3.

The gas detection device 2 includes a gas sensor 21, a distance sensor 22, and a scanning mechanism 23.

The gas sensor 21 is a laser-type methane gas detector having a known configuration. The gas sensor 21 irradiates the detection light L1, the detection light L1 transmitted through the methane gas receives the reflected light L2 reflected by the plant piping or the like (reflection surface R), and the methane gas on the optical path is determined from the light intensity of the reflected light L2. The cumulative concentration of methane gas is calculated to detect the leakage of methane gas. The wavelength of the detection light L1 is set to an appropriate value (for example, 1.65 μm) according to the absorption band of methane gas. As the gas sensor 21, for example, a laser falcon (model number: LM1A06N-LFA) manufactured by Tokyo Gas Engineering Solutions Co., Ltd. is used.

The distance sensor 22 is a radar-type distance sensor having a known configuration, and emits distance measurement light L3 to measure the distance (optical path length) to the reflection surface R. As the distance sensor 22, for example, Trimatiz LiDAR manufactured by Trimatis Co., Ltd. is used. The distance sensor 22 is not limited to the one independent of the gas sensor 21, and may be integrally configured.

The scanning mechanism 23 is a pan head on which the gas sensor 21 and the distance sensor 22 are mounted. By driving a motor (not shown), the scanning mechanism 23 is configured such that the gantry 24 on which the gas sensor 21 and the distance sensor 22 are mounted can rotate around the vertical axis A1 and can be set to an arbitrary azimuth angle, and the gantry 24 is configured. It can rotate around the horizontal axis A2 and can be set to any elevation angle. As a result, the gas sensor 21 and the distance sensor 22 can be integrally changed in the vertical direction and the horizontal direction. Further, the scanning mechanism 23 is supported by a tripod or the like (not shown), and the gas detection device 2 can be installed at an arbitrary place.

The scanning mechanism 23 is not limited to the one that moves the gas sensor 21 and the distance sensor 22 integrally, and may be the one that moves the gas sensor 21 and the distance sensor 22 separately while interlocking with each other. Further, the scanning mechanism 23 is not limited to the above-mentioned cloud platform, and may be, for example, a rotating mirror that reflects the detection light of the gas sensor 21 and the distance measurement light of the distance sensor 22 in the vertical direction and the horizontal direction.

The control device 3 controls the operation of various devices constituting the gas leak detection system 1. The control device 3 is, for example, a general-purpose personal computer having a communication function.

The control device 3 includes a storage unit 31, a coordinate calculation unit 32, and an existence range calculation unit 33. The storage unit 31 stores the installation coordinates of each gas detection device 2, the cumulative concentration data of methane gas measured by each gas sensor 21, the distance data measured by each distance sensor 22, and the like. When the coordinate calculation unit 32 and the existence range calculation unit 33 are collectively referred to, they are referred to as an arithmetic unit.

The gas detection device 2 includes a camera 25. The camera 25 photographs the appearance of the plant. The image taken by the camera 25 is stored in the storage unit 31 or displayed on the display unit 4 such as a liquid crystal display.

Further, a GPS / IMU sensor (not shown) may be installed in the gas detection device 2. By providing the GPS / IMU sensor, it is possible to accurately measure the installation coordinates of each gas detection device 2 and the postures of the gas sensor 21 and the distance sensor 22.

Next, the operation of the gas leak detection system 1 will be described with reference to FIGS. 2 and 3. FIG. 2 is a schematic view showing a gas detection device 2 arranged in the plant. FIG. 3 is a diagram showing a state of identifying a gas leak source.

[Data collection]
The gas detection device 2 is arranged at a plurality of survey points (reference points). The coordinates of the reference point are stored in the storage unit 31. In at least two or more gas detection devices 2 arranged at different reference points, the coordinates of each reference point are set so that the measurement range of each gas sensor 21 and the measurement range of each distance sensor 22 overlap at least in part. To. In particular, the coordinates of the reference point are set so that the location where gas leakage tends to occur in the plant (for example, a valve) is arranged in the area where the measurement range of the gas sensor 21 and the measurement range of the distance sensor 22 overlap. It is preferable to be done.

When conducting a survey at a plurality of survey points, one gas detection device 2 may be sequentially moved to perform measurement at each reference point, or as shown in FIG. 2, a plurality of gas detection devices 2 may be arranged at arbitrary reference points and measurements may be performed substantially at the same time. Although FIG. 2 shows a gas leak detection system 1 in which two gas detection devices 2 are arranged on both sides of a pipe, the number of gas detection devices 2 installed is three or more. It doesn't matter.

The gas sensor 21 measures the cumulative concentration of methane gas from the gas sensor 21 to the surface (reflection surface R) of a pipe or the like. By rotating the scanning mechanism 23 around the vertical axis A1 or the horizontal axis A2, the azimuth and elevation angles of the gas sensor 21 mounted on the gantry 24 are arbitrarily changed, and the cumulative concentration of methane gas is detected over a wide range. Can be done. The cumulative concentration data of methane gas measured by the gas sensor 21 is stored in the storage unit 31.

Further, the distance sensor 22 is mounted on the gantry 24 together with the gas sensor 21, and the azimuth angle and the elevation angle are arbitrarily changed together with the gas sensor 21. Then, the distance sensor 22 measures the distance from the gas sensor 21 to the reflection surface R at the same time as the measurement by the gas sensor 21. The distance sensor 22 is arranged adjacent to the gas sensor 21, and the distance measured by the distance sensor 22 can be regarded as the distance between the gas sensor 21 and the reflection surface R. The distance data measured by the distance sensor 22 is stored in the storage unit 31.

[Coordinate calculation]
The coordinate calculation unit 32 is radiated from the distance sensor 22 based on the rotation angles of the vertical axis A1 and the horizontal axis A2 of the scanning mechanism 23 when the distance sensor 22 makes a measurement, that is, the elevation angle and the azimuth angle of the gantry 24. The direction of the distance measuring light L3 is calculated. Further, the coordinate calculation unit 32 calculates the three-dimensional coordinates of the reflection surface R based on the direction of the distance measuring light L3, the measured value of the distance sensor 22, and the reference point coordinates of the gas detection device 2.

The three-dimensional coordinates of the reflection surface R calculated by the coordinate calculation unit 32 are stored in the storage unit 31 by linking with the cumulative concentration data of methane gas at each coordinate.

Further, by integrating the three-dimensional coordinates of a large number of reflecting surfaces R calculated by the coordinate calculation unit 32, point cloud data indicating the structure of a pipe or the like can be obtained. If the 3D coordinates of the plant are known in advance, such as gas leak detection performed from the second time onward for the same plant that has already acquired the 3D coordinates, the reference point coordinates are specified. Then, it is not necessary to measure the distance data with the distance sensor 22 and obtain the point cloud data (three-dimensional coordinates) of the entire plant again.

[Narrow down the range of existence]
The existence range calculation unit 33 specifies the range in which the leakage of methane gas is detected from the three-dimensional coordinates of the reflection surface R where the cumulative concentration data of methane gas is equal to or higher than a predetermined threshold value and the reference point of the gas detection device 2.

For example, as shown in FIG. 3, in the range measured at the first survey point (solid line part), the inside of the substantially triangle with the first survey point, point A and point B as the vertices is the leakage of methane gas. Is in the suspected range. In addition, in the range measured at the second survey point (broken line part), the inside of the approximately triangle with the first survey point, points A'and B'as the vertices is the range where methane gas leakage is suspected. Become. However, at any reference point, the actual diffusion condition of methane gas is unknown in the depth direction of the optical path of the detection light L1 (the direction from the bottom to the top on the paper in FIG. 3), and leakage of methane gas is suspected. It is inevitable that the range will expand excessively.

On the other hand, the existence range calculation unit 33 is a region where a plurality of methane gas leakage detection ranges overlap based on the range measured at the first survey point and the range measured at the second survey point (the range where the leakage of a plurality of methane gas is detected overlaps. By extracting (the filled area in FIG. 3), the existing range of methane gas can be narrowed down in the depth direction of the detection light L1 so as to approach the range in which the methane gas is actually diffused.

Further, the methane gas whose operator has been narrowed down is displayed on the display unit 4 by superimposing the area where the range where the leakage of the plurality of methane gas is detected overlaps on the image of the appearance of the plant taken by the camera 25. The range of existence can be visualized so that it can be intuitively recognized.

[Estimation of leak source]
Furthermore, the source of the methane gas leak is estimated from the three-dimensional coordinates of the piping in the plant obtained in advance and the three-dimensional data of the reflecting surface R corresponding to the region where the ranges where the leakage of a plurality of methane gas is detected overlap. (In the case of FIG. 3, the range from the leak source to the point B).

In this way, the gas leak detection system 1 according to the present embodiment detects gas leaks over a wide range by scanning the gas sensor 21 and the distance sensor 22 in the vertical direction or the horizontal direction using the scanning mechanism 23. Furthermore, the computing device can narrow down the existence range of methane gas in the depth direction of the optical path of the detection light L1 by extracting the area where the range where the leakage of methane gas is detected overlaps in the measurement at each reference point. it can.

Further, the three-dimensional coordinates of the reflection surface R are calculated based on the distance data measured by the distance sensor 22, the azimuth and elevation angles of the distance sensor 22, and the coordinates of the reference point where the gas detection device 2 is installed, and the calculation device reflects. The leakage source of methane gas can be accurately estimated based on the three-dimensional coordinates of the surface R and the existence range of methane gas limited by the depth direction of the optical path.

It should be noted that the present invention can be modified in various ways as long as it does not deviate from the spirit of the present invention, and it is natural that the present invention extends to the modified ones.

1 ・ ・ ・ Gas leak detection system 2 ・ ・ ・ Gas detection device 21 ・ ・ ・ Gas sensor 22 ・ ・ ・ Distance sensor 23 ・ ・ ・ Scanning mechanism 24 ・ ・ ・ Stand 25 ・ ・ ・ Camera 3 ・ ・ ・ Control device 31 ・・ ・ Storage unit 32 ・ ・ ・ Coordinate calculation unit 33 ・ ・ ・ Existence range calculation unit 4 ・ ・ ・ Display unit A1 ・ ・ ・ Vertical axis A2 ・ ・ ・ Horizontal axis L1 ・ ・ ・ Detection light L2 ・ ・ ・ Reflected light L3・ ・ ・ Distance measurement light R ・ ・ ・ Reflective surface

Claims (8)

A gas leak detection system that detects methane gas leaks from the measurement target.
A laser-type gas sensor that irradiates the measurement target with detection light to detect leakage of methane gas on the optical path to the reflection surface, and a distance measurement light that irradiates the measurement target with distance measurement light to detect the leakage of methane gas from the gas sensor to the reflection surface. A gas detection device including a distance sensor for measuring the distance to the gas sensor, and a scanning mechanism capable of scanning the detection light of the gas sensor and the distance measurement light of the distance sensor in the vertical direction or the horizontal direction.
An arithmetic unit that limits the existence range of methane gas in the depth direction of the optical path based on the range in which the gas sensor detects the leakage of methane gas at each reference point when the gas detection device measures at different reference points. ,
A gas leak detection system characterized by being equipped with. The calculation device calculates the three-dimensional coordinates of the measurement target based on the distance from the gas sensor to the reflection surface measured by the distance sensor, and the methane gas leaks based on the three-dimensional coordinates of the measurement target. The gas leak detection system according to claim 1, wherein the location is estimated. The gas leak detection system according to claim 1 or 2, wherein the scanning mechanism is a pan head on which the gas sensor and the distance sensor are mounted. The gas leak detection system according to claim 1 or 2, wherein the scanning mechanism is a rotating mirror that scans the detection light of the gas sensor and the distance measurement light of the distance sensor. A gas leak detection system that detects methane gas leaks from the measurement target.
A laser-type gas sensor that irradiates the detection light toward the measurement target to detect leakage of methane gas on the optical path to the reflection surface, and a scanning mechanism that can scan the detection light of the gas sensor in the vertical or horizontal direction. Gas detector equipped with
An arithmetic unit that limits the existence range of methane gas in the depth direction of the optical path based on the range in which the gas sensor detects the leakage of methane gas at each reference point when the gas detection device measures at different reference points. ,
A gas leak detection system characterized by being equipped with. A storage unit for storing the three-dimensional coordinates of the measurement target is further provided.
The gas leak detection system according to claim 4, wherein the arithmetic unit estimates a location where the methane gas is leaking based on the three-dimensional coordinates of the measurement target. A gas leak detection method that detects methane gas leaks from the measurement target.
While scanning the laser gas sensor in the vertical or horizontal direction, the detection light is irradiated toward the measurement target to detect the leakage of methane gas on the optical path to the reflection surface.
While scanning the distance sensor following the gas sensor, the distance measurement light is irradiated toward the measurement target to measure the distance from the gas sensor to the reflection surface.
When the gas sensor and the distance sensor make measurements at different reference points, the existence range of methane gas is limited in the depth direction of the optical path based on the range in which the gas sensor detects the leakage of methane gas at each reference point.
A gas leak detection method characterized by this. A gas leak detection method that detects methane gas leaks from the measurement target.
While scanning the laser gas sensor in the vertical or horizontal direction, the detection light is irradiated toward the measurement target to detect the leakage of methane gas on the optical path to the reflection surface.
When the gas sensor measures at different reference points, the existence range of methane gas is limited in the depth direction of the optical path based on the range in which the gas sensor detects the leakage of methane gas at each reference point.
A gas leak detection method characterized by this.

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