JPS6355646B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gas leak detection device that detects gas leakage from a protected object such as a liquefied gas storage tank based on changes in infrared radiation from the protected object.

Conventionally, when detecting a gas leak due to a breakage accident of a liquefied gas storage tank, multiple gas detectors 2 are installed around the tank 1 as shown in Figure 1, and the gas concentration around the tank 1 is detected. Leakage of gas G is detected based on changes in concentration. However, due to wind direction or wind force, the leaked gas G may not reach the detector 2, and damage may not be detected promptly.

Furthermore, as shown in FIG. 2, there is a device in which a temperature sensor 3 is attached to the surface of the tank 1 to detect the cooling of the tank surface by the gas G leaking from the damaged part. However, if there is a leak at an intermediate point of the temperature sensor 3, the cooling temperature may not be transmitted to the sensor 3. Therefore, although the detection accuracy can be improved by closely attaching the temperature sensors 3, it is economically difficult to attach a large number of sensors.

This invention was made based on the above circumstances, and an object of the present invention is to obtain a highly reliable gas leakage detection device that can reliably detect gas leakage from a protected object.

An embodiment of the present invention will be described below with reference to the drawings.

This embodiment shows a case where a plurality of tanks 1 are monitored as shown in FIG. 3, and the monitor camera 4 installed can change the photographing direction and photographing magnification. Therefore, as shown in FIG. 4, an image signal from the monitor camera 4 is converted into a digital signal by a converter 5 and inputted to a processing device 6, and sensors 7 and 8 detect the photographing direction of the monitor camera 4. A sensor 9 for detecting the photographing magnification is added, and the direction signal and the photographing magnification signal of the monitor camera 4 are input to the processing device 6.

The monitor camera 4 is equipped with a filter that removes visible light and passes only the infrared rays emitted from the low-temperature object, and can display the temperature of the low-temperature object as bright and dark on the monitor television.

The converter 5 is designed to generate a reference clock from a built-in timer, and converts the image signal output from the monitor camera 4 from analog to digital (A-D) into a digital signal in synchronization with this clock. It's something you get.

The processing device 6 processes the digital signal obtained by the converter 5 into digitized pixels of n horizontal direction and m vertical direction and stores it in a memory, and stores the information obtained in this way in advance. It compares the memorized tank shape, outline, and information such as piping displayed on the screen to check whether there are any parts that have newly become colder than the surrounding area, and if an abnormal part is found as a result of the check, an alarm is issued. It is something that emanates.

In the above configuration, an image signal from the monitor camera 4 photographing the surface of the tank 1 is given to the monitor television and also to the converter 5. The image signal applied to the converter 5 is A-to-D converted in synchronization with a reference clock generated from a timer. The digital signal obtained by the A/D conversion is written into the internal memory of the processing unit 6 before the next clock signal is generated. Thereafter, the same processing is repeated one after another, and the image signal from the monitor camera 4 is processed into digitized pixels of n in the horizontal direction and m in the vertical direction, and is stored in the memory. The information obtained in this way is compared with previously stored information on the tank shape, outline, piping, etc. displayed on the screen, and a check is made to see if there are any areas that have newly become colder than the surrounding area. As a result of the check,
If an abnormal part is discovered, an alarm will be issued and you will be notified that there is an abnormality.

The above is the basic operation, and in addition to this operation, the direction signal and photographing magnification signal of the monitor camera 4 are given to the processing device 6 separately from the image signal.
This serves as a reference signal for identifying the tank 1 displayed on the screen during shooting. That is, monitor camera 4
The direction signal indicates that the camera has moved horizontally or vertically, and indicates which tank 1 is within the field of view of the monitor camera 4 among the tanks installed on the premises, or which tank 1 is within the field of view of the monitor camera 4. It is used to determine whether the image is taken in such a way. Furthermore, since the shape of the tank 1 in the photograph varies depending on the magnification of the camera, the size of the image being photographed is corrected based on the photographing magnification signal.

In this way, the monitor camera 4 is sequentially moved to take pictures of the tanks installed in the premises, and the photographic data that is input every moment is processed to match the photographed screen with the normal data that is stored in advance. Compare parts. During this comparison and judgment, the outline of the photographed object causes an error and is therefore excluded from the comparison. In the remaining image, it is determined which part of the tank has a localized low temperature due to a gas leak, or a part where the absolute value of the temperature has fallen to the gas vaporization temperature, and an alarm is issued.

Therefore, according to this embodiment, gas leakage in the tank 1 can be monitored over the entire surface of the tank 1 in a non-contact manner. In addition, by increasing the resolution of each digitized pixel,
Blind spots in gas leak detection can be reduced.

By changing the shooting direction of the monitor camera 4, the range monitored by one camera can be expanded, and the result of processing as if there is a gas leak due to noise superimposed on the image signal can be avoided by changing the camera position. By changing the photographic magnification, it can be determined whether the image is a leaked image or an image caused by dirt or scratches on the camera. That is, by changing the position of the camera or zooming, dust or scratches will be fixed within the screen, and leakage will cause the image to move within the screen. Furthermore, by zooming, a small leak that is only one point of data becomes data of several points, making it possible to make a reliable judgment, removing disturbance factors, and enabling highly reliable monitoring.

Note that this invention is not limited to the above embodiments. For example, in the above embodiment, the image signal is A-
A D converter is used to convert the signal into a digital signal, but with recent technology, it is also possible to directly convert the signal into a digital signal using a monitor camera. It is also possible to omit. Further, in the above embodiments, an example in which local cooling is caused by a gas leak has been described, but the present invention can also be applied to detecting the ejection of a high-temperature object due to a piping accident or the like. It goes without saying that various other modifications can be made without departing from the gist of the invention.

As explained above, according to the present invention, it is possible to obtain a highly reliable gas leakage detection device that can reliably detect gas leakage from a protected object.

[Brief explanation of the drawing]

1 and 2 are diagrams for explaining a conventional gas leak detection means, and FIGS. 3 and 4 are diagrams showing an embodiment of the present invention.
The figure shows the installation position of the monitor camera, and FIG. 4 is a block diagram of the gas leak detection device in this embodiment. 1...Liquefied gas storage tank, G...Leaking gas,
4... Monitor camera, 5... Converter, 6... Processing device, 7, 8... Shooting direction detection sensor, 9... Shooting magnification detection sensor.

Claims (1)

[Claims] 1 Photographing the entire surface of a protective object containing gas inside with variable photographing direction and magnification
A TV camera, a means for extracting only the image signal by radiated infrared rays from the image signal from the TV camera and correcting the photographing magnification, and an output image of the means and a standard image of the corresponding photographing direction and photographing magnification. 1. A gas leak detection device characterized by comprising: a determination means for comparing the positions and determining that gas is leaking from the position of the difference when a difference is detected.