JP2009198399A - Gas leak detection system and computer program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology capable of detecting gas leak from a pipe or a flange remotely and simply. <P>SOLUTION: This system for detecting gas leak based on photographing of a long focal optical system is equipped with: a photographing means for photographing continuously a subject irradiated with parallel light or light similar to the parallel light by a camera in the long focal optical system; an operation means for converting continuous image data photographed by the photographing means into vector display image data for displaying by a vector, movement of particles in a plurality of image data by optical flow processing; and an output means for outputting and displaying the vector display image data acquired by conversion performed by the operation means. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an apparatus and a computer program for finding a location of a gas leak that occurs at a joint of a pipe that carries gas or checking for the presence of a gas leak.

There are various causes for gas leakage in the gas pipe. Probably, the case where gas leaks from the flange portion is higher than the case where gas leaks due to a pipe tear due to deterioration of the pipe itself. As one of the causes of gas leakage from the flange portion, there is deterioration or damage of a gasket (packing) used at a joint of piping.
Technologies related to gas leakage include techniques for ensuring inspection and maintenance, techniques that can rationalize inspection and maintenance, and techniques that can be immediately detected when a gas leak occurs.

  As a technique that can be immediately detected when a gas leak occurs, there is a technique of “gas insulation bus” disclosed in Patent Document 1. The gas-insulated bus disclosed in Patent Document 1 is a technique that includes a flange cover that covers a flange portion so that a gas leakage point in the flange portion can be detected quickly and sufficient insulation performance can be obtained.

JP-A-10-234125

  However, this technique is economically burdensome because the flange cover must be attached to all the flanges. In addition, it is a technology that can only be used for piping that can be fitted with a flange cover, and in many cases it cannot be used when the installation space is limited in relation to adjacent machines, etc., and the actual sites that can be realized are limited.

  When it is found that a gas leak has occurred, in order to identify which flange is the cause, the flange is often inspected. When the gas passing through the pipe is hot, there are some sites where humans cannot approach until it is cooled. In such a field, a method is often used in which a piece of cloth is hung from the end of a long bar as shown in FIG.

There is also a schlieren method that detects gas leak detection through photography. This method is illustrated in FIG.
The Schlieren imaging method is a method of imaging by visualizing the density difference between gas and liquid (or transparent body) in a visible form. A light source 1 such as a mercury lamp, a pinhole 2 that receives light from the light source 1, a first plane mirror 3 that reflects the light irradiated to the pinhole 2 and diffuses it into parallel light 3, and the first plane mirror A first collimator 4 for reflecting the light reflected by 3 as parallel light and hitting the subject 9; a second collimator 5 for reflecting the light reflected by the first collimator 4 in another direction for photographing; The second plane mirror 6 that reflects the light reflected by the second collimator 5 toward the camera, the knife edge 7 that cuts the bundle of light reflected by the second plane mirror 6, and the light that the knife edge 7 cuts The high-speed camera 8 is set and executed.

  According to the Schlieren method, an invisible phenomenon of gas leakage can be photographed without approaching the pipe, and this is a candidate technique as a method for finding a flange leaking gas. This is because gas leakage is transparent with no visible particles, and therefore PIV (Particle Image Velocimetry), which is based on the premise of photographing particles, cannot be used.

The Schlieren method described above can be adopted as long as it captures a gas leaking flange, but it is not practical as a technique for finding a gas leak from the flange portion. This is because it takes too much time to set various devices (light source 1 to knife edge 7) for applying parallel light to the subject. That is, the purpose is not to photograph the flange that is leaking gas, but in order to identify which flange is leaking gas, a number of flanges must be photographed. This is because as many setting operations as necessary are required.
In addition, although the probability is small, if it is attempted to detect a gas leak from a pipe other than the flange, the setting work becomes enormous.

The problem to be solved by the present invention is to provide a technology capable of easily and remotely detecting a gas leak from a pipe or a flange without changing the existing equipment.
An object of the invention described in claims 1 to 3 is to provide a gas leak detection system that can easily detect a gas leak from a pipe or a flange remotely.
Another object of the present invention is to provide a control program for a gas leak detection system that can easily detect gas leaks from pipes and flanges remotely.

(Claim 1)
The invention according to claim 1 relates to a system for detecting gas leakage based on photographing by a long focal length optical system.
That is, a photographing means for continuously photographing a subject irradiated with parallel light or light close to parallel light with a long-focus optical system camera, and continuous image data photographed by the photographing means is subjected to optical flow processing to obtain particles in a plurality of image data. A gas leak detection system comprising: an operation unit that converts vector motion into vector display image data that is vector-displayed; and an output unit that outputs and displays vector display image data converted by the operation unit.

(Glossary)
“Optical flow processing” is a processing method for determining and measuring where each pixel has moved in the next frame, for example, for an image sequence continuous at a rate of about 30 frames per second. The method of setting a block area consisting of a notice pixel and neighboring pixels that are adjacent to or adjacent to the notice pixel varies from the case of using a constant pixel calculated from experience values etc. Depending on the situation, it may be changed.
"Parallel light or light close to parallel light" refers to natural light based on sunlight, light close to parallel light that is extremely far from the light source, and light that is close to parallel light that is created by a specific device. is there.
The “subject” is a piping system that transports gas. There are a case where only each flange is a subject and a case where not only the flange but also a pipe is a subject. The part to be output by the output means may be a flange or a pipe itself, or may be near the upper part of the actual part. The back wall and the like are reflected in the background of the flange and piping itself and the upper part thereof.
The “long focus optical system” refers to an optical system having a focal length of 100 mm or more. Note that, by using the center portion of the image, the same effect as that obtained by shooting at a longer focal length can be obtained.

(Function)
First, a photographing unit continuously photographs a subject irradiated with parallel light or light close to parallel light with a long-focus optical system camera. Then, the continuous image data photographed by the photographing means is converted into vector display image data in which the motion of particles in the plurality of image data is vector-displayed by optical flow processing. The output means outputs and displays the vector display image data converted by the arithmetic means.
If a gas leak has occurred, a vector exceeding a predetermined value is displayed in the vector display image data obtained by converting the image data. A monitor who visually observes the output means can determine the presence or absence of gas leakage from the vector display image data.

(Claim 2)
The invention according to claim 2 limits the gas leak detection system according to claim 1.
That is, using the vector display image data converted by the calculation means, a determination means for determining whether or not a gas leak has occurred in the subject, and the determination means has a gas leak in the subject. And a gas leak output means for outputting that the subject has a gas leak.
In other words, the determination of the presence or absence of gas leakage and the output of the determination result are automated.

(Glossary)
The “determination means” is a predetermined reference value for comparison judgment using vector display image data at the time of past gas leakage, vector continuity or repeatability in vector display image data, vector length, etc. Judgment based on an algorithm such as judgment based on whether or not the value is exceeded is executed.
The “gas leak output means” includes a display screen, a speaker, or a combination thereof. The determination means outputs a visual output signal to the display screen and an alarm sound output signal to the speaker.

(Function)
Using the vector display image data converted by the computing means, the judging means judges whether or not a gas leak has occurred in the subject. If the determination means determines that a gas leak has occurred in the subject, the gas leak output means outputs that the gas leak has occurred in the subject. As a result, when a gas leak has occurred, a predetermined output is automatically made to the gas leak output means.

(Claim 3)
The invention according to claim 3 limits the gas leak detection system according to claim 1 or claim 2.
That is, in the case where there are a plurality of subjects, a photographing light confirmation unit for confirming whether or not a single subject is irradiated with light suitable for photographing by the photographing unit, and a long-focus optical system camera. A photographing apparatus installation confirmation unit that is installed in a photographing state for the subject and can be changed to a photographing state for another subject, and light suitable for photographing is captured by the photographing light confirmation unit. When it is determined that the image is irradiated, the imaging unit performs imaging, and when the analysis of the imaging data for the one subject is completed by the determination unit, the imaging state for the other subject The photographing apparatus installation confirmation means is controlled so as to change to

(Glossary)
“When there are a plurality of subjects” means, for example, when a flange provided in a gas pipe is used as a subject, and there are a plurality of flanges, a plurality of images are taken if they do not fit in the frame in one shooting. Is required. In that case, there are a plurality of subjects.
The “photographing device installation confirmation unit” is a device or the like for changing the camera to an installation angle suitable for photographing each subject.

(Function)
The photographing light confirming means confirms whether or not one subject is irradiated with light suitable for photographing by the photographing means. When it is determined by the photographing light confirmation means that light suitable for photographing is irradiated on the subject, photographing by the photographing means is executed. The photographing apparatus installation confirmation unit installs the long-focus optical system camera in a photographing state for the subject. When the shooting of the subject is completed, the setting is changed to the setting of the shooting state for the other subject.
As a result, when the analysis on the shooting data of one subject is completed, shooting on other subjects can be performed continuously. Thereby, it is possible to automate and speed up the discovery of the part where the gas leak occurs. Moreover, even if it is gas leak of several places, it can identify.

(Claim 4)
The invention described in claim 4 relates to a control program for controlling a system for detecting gas leakage based on photographing by a long focal length optical system.
The program includes a shooting procedure for continuously shooting a subject irradiated with parallel light or light close to parallel light with a long-focus optical system camera, and continuous image data shot in the shooting procedure using an optical flow process. Causing the control device of the gas leak detection system to execute a calculation procedure for converting the motion of particles in the data into vector display image data that is vector-displayed and an output procedure for outputting and displaying the vector display image data converted by the calculation procedure This is a computer program.

(Claim 5)
The invention according to claim 5 limits the computer program according to claim 4.
That is, using the vector display image data converted by the above calculation procedure, a determination procedure for determining whether or not a gas leak has occurred in the subject, and a gas leak has occurred in the subject in the determination procedure When it is determined that the gas leak has occurred, the control unit of the gas leak detection system is caused to execute a gas leak output procedure for outputting that a gas leak has occurred in the subject.

The computer program according to claim 4 or claim 5 can be made into a chip and used as a control device of a gas leak detection system.
It can also be stored in a recording medium and provided. Here, the “recording medium” is a medium that can carry a program that cannot occupy space by itself, such as a flexible disk, a hard disk, a CD-R, an MO (magneto-optical disk), a DVD- R and the like.

According to the first to third aspects of the invention, it is possible to provide a gas leak detection system that can easily and remotely detect gas leaks from pipes and flanges.
Moreover, according to the invention of Claim 4-5, the control program of the gas leak detection system which can perform the detection of the gas leak from piping or a flange remotely easily was able to be provided.

Embodiments of the present invention will be described with reference to the drawings.
The drawings used here are FIGS. 1 to 4. FIG. 1 is a conceptual diagram showing the first embodiment, and FIG. 2 is a hardware configuration diagram. FIG. 3 is a flowchart, and FIG. 4 shows an example of means for realizing parallel light used in the present embodiment.

(Figure 1)
The first embodiment shown in FIG. 1 shows a pipe that carries a high-temperature fluid and a plurality of flanges (F1, F2, F3,... Fn) as joints thereof, and one of the flanges (in this figure) Indicates a state in which gas leakage (for example, high-temperature steam) occurs in F2).
This gas leakage detection system includes a long-focus optical system CCD camera, an imaging device installation confirmation unit that installs the long-focus optical system CCD camera in a shooting state for one subject, and an arithmetic processing unit that processes the captured image. With.
Further, although not shown in the figure, there is provided a photographing light confirming means for confirming whether or not the subject is irradiated with light suitable for photographing. “Light suitable for photography” refers to natural light based on sunlight, light close to parallel light that is extremely far from the light source, and light close to parallel light created based on the device shown in FIG. is there.

(Figure 2)
FIG. 2 illustrates a hardware configuration centering on the arithmetic processing apparatus described above. The CCD camera continuously shoots at about 30 frames per second. The image data is transmitted to the control terminal in the gas leak detection system. The receiving means of the control terminal receives the image data, and executes optical flow processing by the computing means.
Here, the optical flow processing is a processing method for determining and measuring where each pixel has moved in the next frame with respect to a continuous image sequence. The method of setting a block area consisting of a notice pixel and neighboring pixels that are adjacent to or adjacent to the notice pixel varies from the case of using a constant pixel calculated from experience values etc. Depending on the situation, it may be changed.
Note that the subject is the flange and its surroundings, and the pixels that move due to gas leakage are near the boundary of the flange. In the optical flow process, an error in the boundary region of the object tends to increase. However, in this embodiment, it is not intended for quantitative measurement of gas leakage, but it is only necessary to be able to determine the presence or degree of gas leakage, so the accuracy of equipment and algorithms for accurate measurement in the boundary region is It is not required.

  The calculation result by the calculation means is vector display image data. The image data is output to the monitor of the control terminal. As an operator of the control terminal, if vector display image data is output, the presence or absence of gas leakage can be visually observed.

In the above output means, the operator of the control terminal determines whether or not there is a gas leak, but in order to automate the determination of whether or not there is a gas leak, the following algorithm is adopted.
That is, in the optical flow process, past vector display image data is used, and the presence or absence of gas leakage is automatically determined by comparison. The past vector display image data is stored in the vector display image database, and the determination means compares the result (vector display image data) calculated by the calculation means.

The result of the gas leak judgment is output to the monitor of the control terminal. You may make it output a warning sound with respect to the speaker of a control terminal.
Further, when the output of the vector display image data and the output of the gas leak determination result (gas leak determination result data) are completed, a command signal for controlling the photographing apparatus installation confirmation unit is output. That is, the installation position is changed so that the next flange that should be photographed to determine gas leakage can be photographed. This process is repeated to identify the flange from which the gas leak has occurred.
Even if an operator does not approach the flange, it is possible to specify from which flange the gas leak has occurred.

(Figure 3)
The control procedure of the gas leak detection system will be described with reference to FIG. In this embodiment, it is a system for detecting a gas leak in the vicinity of the flange, and pipe portions other than the flange are not detected.
First, it is confirmed whether or not light for photographing is suitable for photographing. It is a piping facility that takes in natural light, and is suitable if the natural light has a sufficient amount of light for photographing. Even if it is not natural light, if the subject is separated from the light source (for example, when there is ceiling illumination at a high position), the light becomes almost parallel, and even in that case, photographing is possible.

Subsequently, it is confirmed whether or not the CCD camera of the long focus optical system is installed in a shooting state for one subject. Specifically, it is confirmed whether or not the flange that is the subject is in an appropriate position near the center of the finder of the photographing apparatus. If it is not in the proper position, adjust the position with a motor or the like.
When the flanges that are the objects are arranged at a certain interval in the horizontal direction, the photographing apparatus installation checking means sets the CCD camera of the long focus optical system at a certain height and stores in advance the angle at which the position of the flange can be captured. In addition, a drive system such as a motor is controlled.

When the installation of the photographing device can be confirmed, photographing near the flange is executed. Then, the imaging data is visualized and analyzed by the optical flow process described above, and the presence or absence of gas leakage is determined.
If it is determined that there is a gas leak in the imaging data, the fact that the gas is leaking from the flange that was the imaging target at that time is output to the necessary equipment. Specifically, output to the recording device of data related to the fact that gas leakage has been confirmed, output to a gas leakage warning means, and the like.
In addition, in order to confirm the gas leakage from other flanges as well, when the output is completed, the photographing apparatus installation confirmation means is driven to prepare for photographing for photographing the next flange. Repeat shooting until there are no more flanges for shooting. As described above, the process until gas leakage is visualized and detected is automated. The presence or absence of gas leakage may be confirmed by the observer confirming the captured image.
The gas leak position can be specified even when the pipe is hot or not close to the site.

  In the flowchart described with reference to FIG. 3, when it is determined that gas leakage has occurred in the imaging data, the fact is recorded. It may be determined.

(Fig. 4)
FIG. 4 shows an apparatus in which a ring illumination is provided around the tip of the long focal length optical system and a cylindrical hood is wound thereon.
The ring illumination is one in which a large number of LEDs are installed in a donut-shaped casing (the LEDs are partially illustrated in the figure), and the cylindrical hood is made of plastic.
By adopting this device, the directivity of light can be improved, and photographing can be performed with light close to parallel light.

(Comparative example)
Verify the case of gas leak detection by shadow graph method instead of optical flow processing.
“Shadow graph method” uses light refraction to visualize gas by photographing the brightness of light on the film screen in proportion to the primary change rate and secondary change rate of gas density in the flow field. It is a method, and all light can be observed without using a knife edge. When the gas is blown out, partial density is generated and the parallel light is disturbed, which can be taken into the image data. Specifically, if there is a “moy haze” part in the image, it becomes a part where there is a risk of gas leakage.
In the shadow graph method, in order to make it easy to analyze a captured image, it is generally accompanied by a process of enhancing contrast while an observer confirms with eyes. Specifically, luminance subtraction from the background, enhancement by spatial differentiation, gradation contrast adjustment, or a combination thereof.

  In the case of the optical flow processing, since the processing for solving the temporal and spatial differential equations is performed, the same effect as that in which the contrast enhancement processing is automatically performed can be obtained. In addition, since it is displayed as a velocity vector, it is possible to visually grasp the amount of gas leakage, but it is difficult to grasp quantitatively by the shadow graph method. From the above, when compared with the shadow graph method, the gas leak detection can be more easily performed by the optical flow process if the hardware or environment allows continuous shooting.

  The present invention has applicability in piping equipment manufacturing industry, piping equipment maintenance and maintenance industry, and software development industry for piping gas leak detection systems.

It is a conceptual diagram which shows 1st embodiment. It is a hardware block diagram which shows 1st embodiment. It is a control flowchart by a first embodiment. It is a figure which shows the apparatus for implement | achieving parallel light. [A] is a sectional view and [B] is a perspective view. It is a conceptual diagram of the conventional gas leak detection. It is an image figure which shows the imaging | photography principle by the schlieren method.

Explanation of symbols

F1, F2, F3, Fn Flange 1 Light source 2 Pinhole 3 First plane mirror 4 First collimator 5 Second collimator 6 Second plane mirror 7 Knife edge 8 High-speed camera 9 Subject

Claims (5)

A system for detecting gas leaks based on imaging by a long-focus optical system,
Photographing means for continuously photographing an object irradiated with parallel light or light close to parallel light with a long-focus optical system camera;
Arithmetic means for converting the continuous image data captured by the imaging means into vector display image data in which the motion of particles in a plurality of image data is displayed as a vector by optical flow processing;
An output means for outputting and displaying the vector display image data converted by the computing means. Using the vector display image data converted by the computing means, a judging means for judging whether or not gas leakage has occurred in the subject;
A gas leak output means for outputting a gas leak to the subject when the judging means determines that the subject has a gas leak; and
The gas leak detection system according to claim 1, further comprising: When there are a plurality of subjects, photographing light confirmation means for confirming whether or not light suitable for photographing by the photographing means is irradiated to one subject;
An apparatus for confirming the installation of the long-focus optical system, which can be set to the shooting state for the subject and changeable to the shooting state for the other subject, and
When the photographing light confirmation unit determines that the subject is irradiated with light suitable for photographing, the photographing unit performs photographing, and
2. The photographing apparatus installation confirmation unit is controlled to change to a photographing state for another subject when analysis of photographing data for the one subject is completed by the determination unit. Or the gas leak detection system in any one of Claim 2. A control program for controlling a system for detecting a gas leak based on photographing by a long focal length optical system,
The program consists of a shooting procedure that continuously shoots a subject irradiated with parallel light or light close to parallel light with a long-focus optical system camera,
A calculation procedure for converting continuous image data captured in the imaging procedure into vector display image data in which the motion of particles in a plurality of image data is displayed as a vector by optical flow processing,
An output procedure for outputting and displaying vector display image data converted by the calculation procedure;
Is executed by the control device of the gas leak detection system. A determination procedure for determining whether or not gas leakage has occurred in the subject, using the vector display image data converted by the calculation procedure,
When it is determined that the subject has a gas leak in the determination procedure, a gas leak output procedure for outputting a gas leak to the subject;
The computer program according to claim 4, which causes the control device of the gas leak detection system to execute.

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