JP2000206042A - Gas detecting device and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas detecting device and method for rapidly and accurately detecting such gas as CO being generated in a coal silo. SOLUTION: A laser pulse beam is applied to the surface of coal 2 being stored in a coal silo 1 and at the same time, image data are obtained by a camera. When the coal 2 catches fire, generated CO has absorption characteristics for the wavelength of the laser pulse beam. Then, the wavelength of the laser pulse beam is set to a value so that the beam can be absorbed easily and the laser pulse beam is turned off or on to obtain image data by the camera. Then, the image data with the OFF wavelength are divided by those with N wavelength and the presence or absence of CO is judged from the obtained data.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas detecting device and a gas detecting method for detecting whether or not gas is generated from an inspection object.

[0002]

2. Description of the Related Art In a coal silo storing coal, spontaneous combustion of coal is likely to occur. When coal is smoked and heated, CO
(Carbon monoxide) is generated. So in the coal silo CO
Is monitored to detect the presence or absence of smoking and temperature rise.

Conventionally, detection of CO has been performed as follows. That is, the coal silo is provided with a fan for discharging air and a window for introducing outside air. By rotating the fan to discharge air from the silo containing gas (CO) from the silo, fresh air from outside is obtained. By introducing cold air into the silo through a window, the silo is air-cooled to prevent spontaneous ignition of coal. Therefore, air exhausted from the silo by a fan was sampled and chemically analyzed to determine the presence or absence of CO.

[0004]

However, in the above-mentioned conventional method, since the sampled air is mixed with fresh air introduced from the outside, the CO concentration becomes lower than the actual concentration, and the analysis is carried out. The results were unreliable. Also, in the conventional method, C
Even when O was detected, it was not known from which part of the silo CO was generated (that is, where the ignition occurred). Furthermore, since it takes a considerable time from the sampling of air to the time when analysis results are obtained, measures for detecting CO, that is, measures for cooling and extinguishing the silo, are delayed. Incidentally, if CO is detected, (1) dry coal is injected into the silo to cool the coal, (2) water is discharged into the silo to cool and extinguish the fire, and (3) the coal in the silo is discharged. Countermeasures such as taking out the silo are generally adopted. Such gas generation is not limited to coal silos, but also occurs in other storage facilities, pipelines of various gases such as methane gas, H2S, NOx, and SOx.

Accordingly, the present invention provides a rapid
An object of the present invention is to provide a gas detection device and a gas detection method that can accurately detect gas.

[0006]

According to the present invention, there is provided a gas detecting apparatus comprising: a laser light source for irradiating a test object generating a gas having an absorption characteristic depending on the wavelength of a laser beam with a laser beam; Camera that images the inspection target irradiated with light, and the OFF wavelength and ON obtained by the camera
An image processing unit for analyzing the presence or absence of gas based on the image data of the wavelength.

According to the gas detection method of the present invention, a laser light source is turned on / off by irradiating a laser light on / off an object to be inspected which generates a gas having an absorption characteristic depending on the wavelength of the laser light, and an image of an OFF wavelength is turned on. The image of the wavelength is captured by a camera, and the presence or absence of gas is determined by the image processing unit based on the image data of the OFF wavelength and the image data of the ON wavelength.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a perspective view of a coal silo provided with a gas detection device, FIG. 2 is a block diagram showing a configuration of the gas detection device, FIG. 3 is a laser light absorption characteristic diagram of CO, and FIG. 4 is an image without gas. FIG. 5 is an explanatory diagram of an image when gas is present.

First, the structure of a coal silo will be described with reference to FIG. Coal 2 is stored inside silo 1. A monitoring unit 3 and a scanning drive unit 6 for scanning the monitoring unit 3 are provided above the silo 1. The monitoring unit 3 and the scanning drive unit 6 are connected to the control unit 4.
Is connected to a monitor television 5. Monitor television 5
Displays necessary data and the like. Although not shown, a fan for discharging air is provided above the silo 1,
A window for introducing outside air is provided.

FIG. 2 shows the overall configuration of the gas detection device. The monitoring unit 3 includes the camera 11 and the laser light source 1
2 is provided. The laser light source 12 includes a wavelength converter 13. The camera 11 is provided with a shutter unit 24. The shutter unit 24 is an electronic shutter that can be opened and closed at a high speed, and obtains image data from the camera 11 by opening and closing the shutter. Laser light source 12
Are prism 14, half mirror 15, prism 16,
The surface of the coal to be inspected stored in the silo 1 is irradiated with laser pulse light through an optical system including a lens 17 and the like. Preferably, a homogenizer 25 is provided in front of the lens 17.

A part of the laser pulse light incident on the half mirror 15 is incident on the standard gas unit 20 via the half mirror 18 and is incident on the first detector 21 via the half mirror 19. The laser pulse light that has entered the standard gas unit 20 passes through the standard gas unit 20 and enters the second detector 22. The first detector 21 is for correcting the output fluctuation of the laser beam. Further, the second detector 22 includes:
For ON / OFF wavelength identification. The standard gas unit 20 is for calibration for wavelength identification. The camera 11 captures an image of the coal surface irradiated with the laser pulse light, acquires the image data, and inputs the image data to the control unit 4.

Reference numeral 23 denotes a wavelength conversion unit control controller, which is a laser light source 12, a wavelength converter 13, and a second detector 22.
It is connected to the. The control unit 4 is connected to the camera 11, the first detector 21, the second detector 22, the wavelength conversion unit control controller 23, and the like. The control unit 4 includes a CPU or the like, and performs control of each unit, necessary calculations, determination processing, and the like.

FIG. 3 shows the CO (carbon monoxide) absorption characteristics of the laser pulse light. The horizontal axis indicates the wavelength (μm) of the laser pulse light, and the vertical axis indicates the amount of CO absorbed. FIG.
, The laser pulse light has a wavelength of 2.3 μm, 1.5
The absorption of CO is high around μm and 1.2 μm, and 2.64.
It is maximum near 2.13 μm. At other wavelengths, it does not absorb CO. In the present embodiment, the presence or absence of CO in the silo is detected by the method described below using the CO absorption characteristics of the laser pulse light.

Next, a method of detecting CO using the CO absorption characteristics of the laser pulse light shown in FIG. 3 will be described with reference to FIGS. 4 and 5 show waveforms when the homogenizer 25 is not used. FIG. 4 is an explanatory diagram in the case of “no CO”. (A) is an image obtained by the camera 11, of which (1) is an observation image at an OFF wavelength and (2) is an observation image at an ON wavelength. The ON wavelength is one of the wavelengths A, B, and C in FIG. 3, and the OFF wavelength is a wavelength other than A, B, and C. (3) is an analysis observation image obtained by dividing the image data of (1) by the image data of (2).
This division is performed by the control unit 4. These images are displayed on the monitor television 5. FIG. 4B shows (1),
The light intensity of each image of (2) and (3) is shown. O
The N wavelength is a wavelength that is absorbed by the target gas, and the OFF wavelength is a wavelength that is not absorbed by the target gas.

As shown in FIGS. 4A and 4B, "CO
The observation images of the OFF wavelength and the ON wavelength in the case of “absent” are the same, and the light intensity gradually changes to a substantially concentric shape (angle). Therefore, the data of (3) obtained by dividing the image data of (1) by the image data of (2) is "1".

Next, the case of "with CO" will be described with reference to FIG. In FIG. 5, (1) is an observation image at an OFF wavelength, and (2) is an observation image at an ON wavelength. The ON wavelength is one of the wavelengths A, B, and C in FIG. 3, and the OFF wavelength is a wavelength other than A, B, and C. (3) is an analysis observation image, which is obtained by dividing the image data of (1) by the image data of (2). This division is performed by the control unit 4. These images are displayed on the monitor television 5. FIG. 5 (b)
The light intensity of each image of (1), (2), and (3) is shown.

The image at the OFF wavelength in FIG. 5A is shown in FIG.
This is the same as the image in (a), and the light intensity gradually changes concentrically. However, at the ON wavelength of FIG.
Since O is considerably absorbed, the observed image is considerably distorted as shown in the figure, and the light intensity is considerably disturbed. Therefore, FIG.
The image and the light intensity of FIG.
Therefore, the presence or absence of CO can be determined by comparing the data of (3) of FIG. 4 with the data of (3) of FIG.

Next, a method of detecting CO using the principle described with reference to FIGS. 4 and 5 will be described. In FIG. 1, while scanning the monitoring unit 3 by driving the scanning drive unit 6 to observe the coal surface, the coal surface is irradiated with laser light, and the camera 11 obtains image data of the coal surface. The OFF wavelength of (1) and the ON wavelength of (2) are obtained by the method described with reference to FIGS.
The data of the analysis observation image (3) is obtained from the wavelength image data, and the presence or absence of CO is determined. That is, if the data shown in (3) of FIG. 4 is obtained, it is determined that there is no CO, and if the data shown in (3) of FIG. 5 is obtained, it is determined that there is CO.

Further, by intermittently obtaining image data from the camera 11 by opening and closing the shutter 24 at a high speed during the scanning, the distance from the camera 11 to the position where CO is generated is determined based on the obtained data. Can be measured.
That is, the shutter section 24 is a distance measuring means to the gas generation position. Note that the distance measuring method by opening and closing the shutter unit itself is a well-known method, and a description thereof will be omitted.

FIGS. 6 and 7 show the case where the homogenizer 25 is used. In this case, the waveforms indicated by the solid lines in (1) and (2) of FIG. 6B and in FIGS. 7B and (1) (2) and (3) have the characteristics, particularly the high and low levels shown in FIGS. 5, and the presence or absence of gas can be determined more accurately. The waveform shown by the chain line is shown in FIG.
6 is a waveform when the homogenizer 25 shown in FIG. 5 is not used.

This method acquires data while scanning the surface of the coal with the camera 11 or laser light and determines the presence or absence of CO.
Also, the position where CO is generated can be immediately obtained from the scanning position control data of the laser beam or the distance measurement data by the shutter unit 24, so that post-mortem measures such as fire extinguishing measures can be quickly and accurately taken.

In this embodiment, the presence or absence of CO is determined from the image data of (3) obtained by dividing the image data of (1) in FIG. 4 to FIG. 7 by the image data of (2). The specific determination method is not limited to this method. For example, the control unit 4 differentiates the data shown in FIG. 4B or FIG. The point is that the presence or absence of CO may be accurately determined based on the difference between the image data of the OFF wavelength and the image data of the ON wavelength.

The present invention can also be applied to the detection of a gas other than the detection of CO in a coal silo, for example, methane gas, SO2 and NO. In this case, the light absorption characteristics of methane gas, SO2, NO, etc. are as shown in FIG.
Therefore, the wavelength of the laser pulse light is adjusted by the wavelength converter 13 according to the type of the gas to be detected.

[0024]

As described above, according to the present invention, the detection of gas such as CO in a coal silo can be performed simply and accurately, and the detection can be performed in real time. Since it is also possible to take a measure, it is possible to quickly and accurately take measures when gas is detected.

[Brief description of the drawings]

FIG. 1 is a perspective view of a coal silo provided with a gas detection device.

FIG. 2 is a block diagram showing a configuration of a gas detection device.

FIG. 3 is a graph showing a laser light absorption characteristic of CO.

FIG. 4 is an explanatory diagram of an image in a case where there is no gas.

FIG. 5 is an explanatory diagram of an image when gas is present.

FIG. 6 is an explanatory diagram of an image when no gas is present.

FIG. 7 is an explanatory diagram of an image when gas is present.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Coal silo 2 Coal 3 Monitoring unit 4 Control part 11 Camera 12 Laser light source

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] November 25, 1999 (1999.11.
25)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0003

[Correction method] Change

[Correction contents]

[0003]

[Problems to be Solved by the Invention] By the way, in the conventional Western-style toilet, when raising and lowering the toilet seat and the toilet seat lid, it is necessary to grasp them directly with fingers, which is not sanitary and uncomfortable. there were.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0004

[Correction method] Change

[Correction contents]

The present invention has been made in view of the above-mentioned problems of the prior art. A handle is attached to the periphery of a toilet seat and a toilet seat lid, and the handle is grasped to sanitize the toilet seat and the toilet seat lid. It is an object of the present invention to provide a Western-style toilet with a handle that can be raised and lowered without causing any discomfort.

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hirohisa Yoshida 5-717-1, Fukahori-cho, Nagasaki-shi F-term in Nagasaki Research Laboratory, Mitsubishi Heavy Industries, Ltd. 2G059 AA05 BB01 CC04 EE01 EE12 FF01 FF08 GG01 GG08 HH06 HH09 JJ11 JJ12 JJ13 JJ23 JJ30 KK04 MM01 MM09 MM20 NN05

Claims (2)

[Claims] 1. A laser light source for irradiating a laser beam to a test object that generates a gas having an absorption characteristic depending on a wavelength of a laser beam, a camera for imaging the test object irradiated with the laser light from the laser light source, and a camera A gas detection device comprising: an image processing unit that analyzes the presence or absence of a gas based on image data of an OFF wavelength and an ON wavelength obtained from a computer. 2. A camera captures an image of an OFF wavelength and an image of an ON wavelength while irradiating a laser light from a laser light source on / off and irradiating an inspection object that generates a gas having absorption characteristics depending on the wavelength of the laser light with a camera. A gas detection method, wherein the presence / absence of gas is determined by an image processing unit based on the OFF wavelength image data and the ON wavelength image data.