JPH01140039A - Detection of source of leak of gas and apparatus therefor - Google Patents

Abstract

PURPOSE:To expedite detection by a method wherein a point showing an average gas concentration is determined on a segment of a line connecting second and third points of high gas concentrations out of three points extracted sequentially from the point of the gas concentration of the maximum value, and the position of a source leak is determined on a segment connecting said point and a first point of gas concentration. CONSTITUTION:Three points Pa, Pb and Pc are extracted sequentially from a point Pa of gas concentration of the maximum value out of values of gas concentration obtained from a number of points. Next, a point Pd of an average gas concentration is determined on a segment of a line connecting the points Pb and Pc of low concentration. Then, by using a distance between the points Pa and Pd and the values of gas concentration at the points Pa and Pd, a equal concentration curve is formed by computation on an extension of a segment connecting the points Pa and Pd and displayed on CRT. Accordingly, an apparatus according to this method can cope with the leak of gas and can be employed even at a point affected by the wind.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention provides a method for detecting a gas leak source that can easily and reliably detect the gas leak source in the event of a gas leak in a petrochemical combiner 1, etc. METHODS AND APPARATUS.

[Conventional technology]

In a high-pressure gas plant such as a petrochemical combiner 1, there are countless locations such as pumps, valves, flanges, etc., where there is a risk of gas leakage. In the event that flammable or toxic gas leaks from these facilities, the source of the leak must be promptly found, and appropriate safety measures must be taken while monitoring the diffusion status of the leaked gas to prevent secondary disasters from occurring. .

However, conventional gas leak detection and alarm devices only notify an abnormality by displaying a meter for each sensor and by flashing a buzzer or lamp when the detected gas concentration exceeds the alarm setting level, and the search for the source of the gas leak is difficult. This was done using a portable gas detector.

On the other hand, as a method for estimating the source of gas leakage based on gas concentration information from multiple points, JP-A-61-155932
There is one shown in the publication.

[Problem that the invention seeks to solve]

The above-mentioned method of searching for a gas leak source using a portable gas detector has the drawback that it takes time to detect the gas leak source after an alarm is issued, and therefore, it is not possible to respond quickly.

In addition, the above method for estimating the source of gas leaks assumes that there is no wind or that the wind direction and speed are known, even if there is a correlation. There was a point that it could not be applied when the system is working. In addition, if it is assumed that the wind direction and wind speed are known, the wind direction and wind speed will differ depending on the installation point of the gas detector due to the influence of obstacles. It is useless and needs to be installed at each installation point. However, the wind direction.

The problem with anemometers was that they could not be installed in large numbers because explosion-proof and inexpensive anemometers had not yet been developed.

This invention was made to solve the above problems, and an object thereof is to provide a gas leak source detection method and device that can quickly detect the gas leak source regardless of the presence or absence of wind. It is.

[Means for solving problems]

The method for detecting a gas leak source according to this invention is based on the extracted three
Find the average gas concentration point that shows the average gas concentration of both points on the line connecting the second and third highest gas concentration points among the points, and then show this average gas concentration point and the maximum gas concentration. The distance between the average gas concentration point and the first gas concentration point, the gas concentration at the first gas concentration point, and the average gas concentration are used on the extension line of the line segment connecting the first gas concentration point. This method determines the location of the gas leak source.

Further, the gas leak source detection device according to the present invention includes gas detectors installed at a large number of locations, an indicator unit that indicates the gas concentration detected by these gas detectors, and a wind direction. The first from the wind speed indicator, the alarm unit that issues an alarm when the gas concentration detected by the gas detector is above the alarm setting level, and the gas detectors installed at each location.

Equipped with a calculation control unit that extracts the gas concentration points showing the second and third gas concentrations and performs predetermined calculations to extract the gas leak source, and a display unit that monitors the output of each detected part. It is something.

[Operation] The gas leak source detection method of the present invention is to find the average gas concentration point on the line connecting the second and third highest gas concentration points, and to Using the distance between the average gas concentration point and the first gas concentration point and each gas concentration between the average gas concentration point and the first gas concentration point on the extension line of the line segment connecting the high gas concentration point, The source of gas leakage is determined by calculation.

Further, in the gas leak source detection device of the present invention, gas leaks are detected by gas detectors installed at multiple locations, and the respective gas concentrations are indicated by an indicator unit, as well as the wind direction and wind speed at that time. Indicated by wind speed and direction indicators.

Further, if the concentration of any one of the gases detected by each gas detector is equal to or higher than the alarm setting level, the alarm unit issues an alarm.

Then, in the arithmetic and control unit, a calculation is performed using the gas leakage source detection method of the present invention, the gas leakage source is estimated, and necessary display is performed on the monitor on the display unit.

〔Example〕

First, an embodiment of the method for detecting a gas leak source according to the present invention will be described with reference to FIG.

Among the gas concentrations obtained from many points, three points are sequentially extracted from the point with the maximum gas concentration at any given time,
These points are sequentially p,, pb.

Let it be Po.

Now, in general, the gas concentration C at a point at a distance X from the gas leak point is expressed as: C=Ax-'' where A: constant B: attenuation coefficient.

Now, let Ca be the concentration of each gas at point p, Pb, and Pc.

Since Cb and Ca are C, > Cb > Cc, it is considered that the leaked gas flows and diffuses from the direction of point P toward the points Pb and Pc due to the wind. Let the average concentration of points pb and p on the low concentration side be 04,
9 points p a (that is, points) 1 b of this average concentration cm,
The distances L ha and L ad on the line segment connecting P are calculated using the following formula.

L ba: L ad= C6": Cc "This determines the point P1L.

Next, a point P0 is found on the extension of the line segment connecting points )', , )', and i using the formula, and is estimated to be the source of the gas leak.

L,,l=L o-+L-a The calculation of the above estimation is based on the output of multiple gas detectors.
This can be done when one of them reaches a certain level, for example, an alarm level.

FIGS. 2(a), (b), and (C) show simulation results of the gas leak source estimation method of the present invention.

In this simulation, gas detectors were arranged at 4 m intervals in a grid pattern, and the height of the gas leak source was set to 0.2 m in both Figures 2 (a), (b), and (C), and the leak direction was set to 2 m. Figure (a
), (b) is horizontal, Figure 2 (c) is downward, Figure 2 (a) is ethylene 5017m1n, Figure 2 (b) is ethylene 201/lll1n, Figure 2 (C) is the case of a gas leak source of 0.00000000000000000000000min.

The X mark indicates the gas leak source, and the * mark is an estimated mark of the gas leak source, and these estimated marks are marked one after another every 8 seconds. The wind direction and wind speed change from moment to moment, and it is difficult to identify the source of gas leakage with only one estimated mark, but as the number of estimated marks increases, the gas leaks will be concentrated in a specific location. This particular location is shown in Figure 2 (n
) to (e), it is near the actual gas leak source indicated by the X mark, indicating that the gas leak source estimation method of the present invention is effective.

Next, an embodiment of the gas leak source detection device according to the present invention will be described with reference to FIG.

In Figure 3, ■ is the gas detection panel, ■ is the monitor device, and ■ is the gas detection panel.
indicates a fiber optic cable. The gas detection panel■ has gas detectors 1□, 1□, etc. installed at many locations.
・, 1) (Hereinafter, when collectively referred to, it will be simply referred to as 1. The same applies to other symbols.) Indicator unit l"21t12y . . .

2.1, a wind direction/wind speed indicator 4 that displays the output of the wind direction/wind speed transmitter 3, an alarm unit 5 that issues an alarm when the output of the gas detector 1 exceeds the alarm setting level, and these indicator units. 2. Wind direction and speed indicator 4. A communication unit (skinning unit) 6 is provided for sending the output of the alarm unit 5 to the monitor device (2). and,
The output of the 4S unit 6 is connected to an optical fiber cable 2 via an optical modem 7.

The monitor device (2) includes CR'r8 as a display section and CPU9. It is equipped with an FDDlo, a keyboard 1), etc., and is connected to an optical fiber cable 1 via an optical modem 12.

Next, the operation will be explained.

When power is supplied to the gas detector 1, the gas concentration signal from each gas detector 1 is received, and the respective gas concentration is displayed on the meter of the indicator unit 2. When the gas concentration exceeds the alarm setting level, An alarm is emitted from the alarm unit 5. In addition, each indicator unit 1-2 is equipped with a digital output mechanism, and the communication unit 6 transmits gas concentration data and alarm data from up to 255 points to the R3-232.
Convert to 0 signal. Since the signal transmission distance of R3-2320 is generally short, the optical modem 7 converts the signal into an optical signal, transmits the signal through the optical fiber cable (2), and sends it to the monitor device (2).

In the monitor device ■, the gas concentration and alarm information sent as optical signals are transmitted via the optical modem 12 to the It S-232C.
Convert it back to a signal and receive it.

When the gas concentration exceeds the alarm setting level (for example, 500 ppm), the gas concentration at the midpoint is calculated from the concentration difference between each gas detector 1, and an isoconcentration curve is displayed on C) r8.

FIG. 4 shows an example of an isoconcentration curve, where the O mark indicates the installation point of the gas detector 1, and p , , p bp P Q are the first, second, and third points as in FIG. represents the th gas concentration point. This example is an isodensity curve expressed with the first point P as a reference, and although it changes from moment to moment, the current state is displayed at every predetermined time.

Isoconcentration curves are an extremely effective means for understanding the behavior or diffusion status of leaked gas, and in this example, 1 to 3
Book (3 colors: white, yellow, red) on C1, graph on 8, f
It can be displayed on the screen and can be set arbitrarily in units of OOppm by key operation on the keyboard 1). 1 (When a gas detector 1 at an IAI location or higher detects a gas concentration higher than the alarm setting level, the position of the set equal concentration between adjacent gas detectors 1 is automatically calculated, and the CR
'l' Display on 8.

Further, when a gas concentration higher than the alarm setting level is detected at three or more locations, the CPU 9 estimates the location of the gas leak source using the gas leak source detection method of the present invention described above, and
) Display the leakage estimation mark on the screen. Mochiro/shi;
The concentration for each gas detector 1 can be displayed as a bar bluff or digitally by switching the screen.

FIG. 5 shows a partially cutaway perspective view of a hot wire type semiconductor sensor as an example of a gas sensor used in gas detector 1 (FIG. 3). As shown in FIG. A metal oxide semiconductor layer 1-2 of SnO is sintered on top of the platinum coil 1-1.The platinum coil 1-1 has a heater function to maintain a constant temperature and a signal detection function.Platinum coil 1-1 When the metal oxide semiconductor layer (hereinafter referred to as the semiconductor layer) 1-2 heated to a constant humidity (300 to 450°C) absorbs an electron-donating gas such as a combustible gas, the semiconductor layer 1 -2 surface electron concentration increases.

Therefore, the electrical conductivity of the semiconductor N1-2 itself changes.

Further, due to the change in electron concentration on the surface of the semiconductor layer 1-2, heat dissipation on the surface of the semiconductor layer 1-2 improves, and the temperature of the platinum coil 1-1 decreases. Therefore, platinum coil i-
The resistance value of 1 becomes low.

In this way, combustible gas is detected using two effects: electrical conduction effect and thermal conduction effect.

The basic circuit is shown in FIG. In this figure, S is the gas sensor mentioned above, S' is the temperature compensation element, I't1. R.

is a resistor and E is a power supply.

〔Effect of the invention〕

As explained above, the method for detecting the gas leak source according to the invention of Party B is to detect the average gas concentration on the line segment connecting the second and third highest gas concentration points among the three extracted locations. Find the concentration point, and then add a line between the average gas concentration point and the first gas concentration point on the extension of the line segment connecting this average gas concentration point and the first gas concentration point showing the maximum gas concentration. Since the location of the gas leak source is determined using the distance, the gas concentration at the first gas concentration point, and the average gas concentration, it is possible to not only immediately respond to a gas leak, but also
This is an innovative product that can be applied to outdoor plants where there is wind, and we hope that it will be widely used in the future.

Further, as explained above, the gas leak source detection device according to the present invention includes gas detectors installed at a large number of locations and instructions for indicating the gas concentration detected by these gas detectors. a wind speed and direction indicator; an alarm unit that issues an alarm when the gas concentration detected by the gas detector is above the alarm setting level; It is equipped with a calculation control unit that extracts the gas concentration point showing the second and third gas concentration and performs predetermined calculations to extract the source of gas leakage, and a display unit that monitors the output of each detected part. You can see the output of each gas detector at a glance, and the wind direction and speed are also displayed.
It is easy to take measures in the event of a gas leak.Furthermore,
Since the output of each part can be displayed on the display of the monitor, it is possible to display the detection results of each gas detector in the form of isoconcentration lines, bar graphs, etc., so it is possible to display not only gas leak sources but also
This has the advantage that other necessary information can be easily displayed.

[Brief explanation of the drawing]

Fig. 1 is a diagram for explaining an embodiment of the gas leak source detection method of this invention, Fig. 2 is a diagram for explaining the simulation results of this invention, and Fig. 3 is a diagram for explaining an embodiment of the gas leak source detection method of this invention. FIG. 4 is a block diagram showing the configuration of an embodiment of a fa leak source detection device, FIG. 4 is a diagram showing an example of an isoconcentration curve, and FIG. 5 is a partially cutaway diagram showing an example of a gas sensor used in the present invention. The perspective view shown in FIG. 6 is a basic circuit diagram of the gas sensor shown in FIG. 5. In the figure, 1 is a gas detector, 2 is an indicator unit, 3 is a wind direction/wind speed transmitter, 4 is a wind direction/wind speed indicator, 5 is an alarm unit,
6 is a communication unit, 7.12 is an optical modem, 8 is a
'r, 9 is CPU, 10 is ■・'l)D. 1) (Yo keyboard, 1 is the gas detection panel, ■ is the monitor device, ■ is the optical fiber cable. Figure 1 (a) ・ Figure 4 Figure 5 Figure 6

Claims (4)

[Claims] (1) Among the gas concentrations obtained from many points, extract three points in sequence starting from the point with the maximum gas concentration, and line connecting the second and third highest gas concentration points among these three points. Find the average gas concentration point showing the average gas concentration of both on the minute, and then place it on the extension line of the line segment connecting this average gas concentration point and the first gas concentration point showing the maximum gas concentration, The gas leakage source position is determined using the distance between the average gas concentration point and a first gas concentration point, the gas concentration at the first gas concentration point, and the average gas concentration. How to detect leak sources. (2) The method for detecting a gas leak source according to claim (1), wherein the extraction of the first gas concentration point is performed when the gas concentration reaches a certain level. . (3) Gas detectors installed at many locations,
an indicator unit that indicates the gas concentration detected by each of these gas detectors, a wind direction/wind speed indicator, and an alarm unit that issues an alarm when the gas concentration detected by the gas detector is equal to or higher than an alarm setting level; The gas concentration points showing the first, second, and third gas concentrations are extracted from the gas detector, and the line segment connecting the second and third highest gas concentration points among these three points is extracted. Find the average gas concentration point showing the average gas concentration of both, and then place the average gas concentration point on the extension line of the line connecting this average gas concentration point and the first gas concentration point showing the maximum gas concentration. an arithmetic control unit that determines a position of a gas leak source using a distance between a gas concentration point and a first gas concentration point, a gas concentration at the first gas concentration point, and the average gas concentration; A gas leak source detection device comprising: a display unit that monitors the output of each part. (4) The gas leak source detection device according to claim (3), wherein the display section displays an isoconcentration curve.