JPS62162939A - Cryogenic fluid leak detection method - Google Patents

Abstract

PURPOSE:To monitor a wide space at low cost and to securely detect a leak of low temperature liquid by detecting variations of a visible light image and a temperature image in the monitor area by a visible-light image detector and an infrared-ray image detector. CONSTITUTION:If the low temperature liquid leaks from piping 1, etc., the temperature near the leak place 6 falls and moisture in the atmosphere is condensed to produce white smoke 7. Temperature variation is detected by the infrared-ray image detector 4 and visual image variation of the white smoke, etc., is detected by the visible-light image detector 4 respectively and they are monitored by a monitor device 5. A line image is varied by any other cause than the leak of the low temperature liquid, but when both images vary at the same time, it is considered that is caused by the leak of the low temperature liquid. Thus, the wide space is monitored at low cost and the leak is detected securely.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for detecting leakage of low-temperature liquefied gas and other low-temperature fluids from piping and various devices in factories and the like.

(Prior art and its problems) Conventionally, to detect leaks of low-temperature fluid in factories, etc., sensors such as gas detectors or thermometers for measuring low temperatures were installed at each location where there was a possibility of leakage. However, this method requires a large amount of money, and maintenance requires a large amount of money and manpower. There is a fundamental flaw in the inability to respond, and this cannot be solved by increasing the number of sensors. A method has also been proposed in which an infrared transmitter emits infrared rays toward a monitoring area, a receiver receives the infrared rays after passing through the monitoring area, and detects the presence of gas based on the absorption spectrum of the infrared rays to detect a leak. However, in addition to requiring the installation of infrared transmitting and receiving devices or reflectors across the monitored area, such methods inherently detect the direction containing the leak. However, in order to identify the leakage location, it is necessary to provide a large number of two-dimensional pairs of transmitting and receiving devices 9 and a means for moving the device for scanning, and as described above, this method also requires the sensor to detect the leakage. It has the same fundamental flaws as installing it in a predicted location.

The present invention solves the above-mentioned conventional problems by very rationally understanding the physical changes that occur when a low-temperature fluid such as low-temperature liquefied gas leaks, and requires monitoring at a low cost. The purpose is to be able to detect leaks in all areas.

(Means for solving the problem) That is, in order to achieve the above-mentioned object, the present invention monitors a target monitoring area by capturing it as a visible light image and an infrared image, and uses the visible light image and infrared image to monitor the target monitoring area. , the gist is to detect the leakage of low-temperature fluid by capturing changes in the visible light region and infrared light region due to the leakage, respectively.

Next, the present invention will be explained based on drawings showing embodiments.

FIG. 1 schematically shows the configuration of an embodiment to which the method of the present invention is applied, in which reference numeral 1 is a pipe through which a low-temperature fluid such as liquefied gas flows, and a rectangle surrounded by a two-dot chain line is shown by reference numeral 2. The frame virtually indicates the monitoring area targeted for leak detection. Reference numerals 3 and 4 indicate a visible light image detector and an infrared image detector that capture the monitoring area 2 as a visible light image and an infrared image, respectively, and reference numeral 5 indicates a visible light image from the detectors 3 and 4. , a monitoring device that monitors leaks based on infrared images.

(Function) When low-temperature fluid leaks from the piping 1, etc., the temperature near the leakage point 6 decreases, and moisture in the atmosphere condenses, generating white smoke in the form of mist or steam. That is,
Due to the leakage of the low-temperature fluid, a change occurs in the visible light region such as the generation of white smoke 7, which appears in the visible light image shown in Figure 2.
In addition, in the infrared light region, a change in temperature decreases, and the second
The white smoke appears in an infrared image (not shown) that captures the same monitoring area 2 as the visible light image in the figure.

Therefore, leakage can be detected by detecting these changes appearing in the visible light image and the infrared image using the monitoring device 5.

By the way, in factories and the like, high-temperature steam is used to keep various devices warm and for other purposes, and this high-temperature steam also forms white smoke, which also appears in visible light images. Furthermore, the temperature drop in the vicinity of the leakage location due to the leakage of the low-temperature fluid is relatively small, and such local temperature drop may also occur due to weather conditions such as wind. Therefore, if only one of the visible light image and the infrared image is used, phenomena other than the leakage of the low-temperature fluid will be detected, and the leakage cannot be reliably identified.

However, if the white smoke that appears in the visible light image is caused by high-temperature steam, such white smoke will appear in the infrared image as an increase in temperature, contrary to the leakage of low-temperature fluid, so it is difficult to distinguish between the two. In addition, even if a local temperature drop appears in the infrared image, if it is caused by weather conditions, it can be determined by the fact that white smoke does not appear in the visible light image. can do. In this way, the present invention can reliably identify a leak of low-temperature fluid by capturing both the changes appearing in the visible light image and the changes appearing in the infrared image.

The above visible light image and infrared image can be monitored by, for example, the following image processing by the monitoring device 5.

That is, the images corresponding to the visible light image and the infrared image are
As shown in the figure, each pixel 8 is divided into a large number of pixels 8.
Changes can be detected by storing data for each pixel 8 and comparing the previous image stored in this way and the current image for each pixel 8. The above-mentioned leakage can be identified by detecting changes in both the visible light image and the infrared light image and making judgments based on such comparison. In addition, the specific method and configuration of image processing may be any suitable method as long as it is a method for detecting the aforementioned changes in visible light images and infrared images.

In addition to completely automatically monitoring visible light images and infrared images through image processing, for example, changes in both or either of visible light images and infrared images can be detected through the aforementioned image processing. It is possible to use a semi-automatic method in which the leak is automatically detected and a person looks at the CRT image based on this detection signal to ultimately identify the leak, or in some cases, a human monitors the leak using the CRT image. It may be configured to do so.

Next, the detectors 3 and 4 that capture the visible light images and infrared images of the target monitoring area 20 can be installed in the following various ways. First, FIGS. 4(a) and 4(b) are examples of cases in which the monitoring target can be seen from one location, and the detector 3.4 is rotatably installed at a high location using a support 9 or the like.
It is possible to monitor the entire wide monitoring area by scanning and zooming.

Figure 5 also shows multiple sets of detectors 3.4 around the monitoring target.
are installed, and each set of detectors 3 and 4 has a limited monitoring area 2.

In addition, the detectors 3 and 4 may be installed in any suitable manner.

In addition, in the present invention, the detectors 3 and 4 are made movable or zoomable as described above, so that they usually monitor a wide monitoring area 2 and detect any change in this state. In such a case, the corresponding location can be enlarged and the above-mentioned image processing etc. can be performed, and leakage can be detected more accurately. In addition, in FIGS. 1 to 3, the monitoring area 2 represents a very narrow area such as a part of the piping 1, but this shows a zoomed state. Of course, the monitoring area 2 can cover a wide area as shown in FIGS. 4 and 5.

(Effects of the Invention) As described above, the present invention detects physical changes when low-temperature fluid such as low-temperature liquefied gas leaks by comparing changes that appear in visible light images and infrared images corresponding to the target monitoring area. Since we consider both the changes that appear and make judgments based on these,
This has the effect that leakage of low-temperature fluid can be reliably identified and detected. The present invention detects changes due to leakage by projecting the three-dimensional space corresponding to the target monitoring area onto a two-dimensional image, so as long as it is visible, one set of The detector can monitor a very wide space, and the location of the leak can be easily identified.For example, a worker can check the location and situation of the leak using an image on a CRT that corresponds to a visible light image. etc., there is an effect that measures against leakage can be taken quickly. Thus, the present invention can detect leaks in all areas requiring monitoring at low cost, and can detect leaks of cryogenic fluids from piping, equipment, etc. in factories, plants, and other suitable locations. There is an effect.

[Brief explanation of drawings]

All the figures correspond to the embodiments of the present invention, and Fig. 1 is a schematic explanatory view of the whole, Fig. 2 is an explanatory view of visible light images, Fig. 3 is an explanatory view of image processing, and Fig. 4 (a ), (b), and FIG. 5 are explanatory diagrams of the method of installing the detector, where FIG. 4(a) is a side view, and FIG. 4(b) and FIG. 5 are plan views. Code 1... Piping, 2... Monitoring area, 3... Visible light image detector, 4... Infrared image detector, 5... Monitoring device, 6... Leakage location, 7...・White smoke, 8...pixels,
9... Strut, 10... Tank.

Claims (1)

[Claims] Monitor the target monitoring area by capturing it as a visible light image and an infrared image, and using the visible light image and infrared image,
A method for detecting leakage of low-temperature fluid, characterized in that leakage is detected by capturing changes in the visible light region and infrared light region due to leakage of low-temperature fluid.