JPH0240967B2 - GASUROEIGENNOKENCHIHOHO - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for detecting a gas leak source, and can be used in particular to search for the leak source when a hazardous gas leaks in a chemical plant facility or the like. [Background technology and its problems] In chemical plant facilities, etc., when dangerous gases such as flexible gases or toxic gases leak, the source of the gas leakage is quickly discovered and safety measures are taken to prevent secondary disasters from occurring. must be prevented from occurring. However, in the past, there was no appropriate means to search for the source of a gas leak, so the search was conducted by relying on the human sense of smell, or by multiple people performing gas detection. However, this method has not been able to satisfy the need to quickly and accurately discover the source of the gas leak. [Object of the Invention] An object of the present invention is to provide a gas leak source detection method that can quickly and accurately detect the gas leak source in response to the above-mentioned requirements. [Means and effects for solving the problem] Therefore, the first invention provides a method for detecting a gas leak source in a state of no wind or near no wind, which detects at least three different sources within an area where leaked gas is diffused. Detect the gas concentration at each of the above points, identify the three points with the highest gas concentration from these gas concentration data groups, and identify the virtual leak source between this highest gas concentration point and the other two points. Find the positions where perpendicular lines passing through each virtual leak source and perpendicular to the straight line connecting the highest gas concentration point and the other two points intersect with each other, and estimate this position as the leak source. It is characterized by Further, a second invention provides a method for detecting a gas leak source in a windy state, which detects gas concentrations at at least three or more different points within an area where leaked gas is diffused or at least three or more different regions. detect each average gas concentration, identify three points or areas with the highest gas concentration and lined up along the wind direction from these gas concentration data groups or average gas concentration data groups,
This highest gas concentration point or area and the second highest
Find the distance to the point or area, and take this distance as L, the distance between the point or area of the highest gas concentration and the estimated leak source _as When the gas concentration at a point or area is C ₂ and the concentration decay constant is B, X: (L-X) = C ₁ ^1/B : C ₂ ^1/B and X: ( _L ⁺ The distance X is obtained from at least one equation of ^B :C ₂ ^1/B , and the leak source is estimated from this X. [Example] First, an example of the detection method of the first invention will be described in the first example.
The diagram will be explained. In this detection method, first, the gas concentration is measured at at least three different points within the zone Z where the leaked gas is diffused. In this case, the selection of gas concentration measurement points is preferably at each intersection of a predetermined matrix, but a plurality of arbitrarily selected points may be used. Next, from among these gas concentration data groups, three points with high gas concentrations are selected, for example, three points P ₁ ,
Identify P ₂ and P ₃ . Normally, when there is no gas leak, the gas concentration at each point is at or close to zero. However, once a gas leak occurs, it is known that the diffused gas concentration attenuates in proportion to X ^- B, where x is the distance from the leak source and B is the concentration attenuation constant. The gas concentration shows a higher value closer to the leak source. Incidentally, the concentration attenuation constant B depending on the distance x with respect to the amount of leaked gas and the wind speed is shown in the following table.

[Table] Current weather conditions are no wind or near no wind.
For example, when the wind speed is less than 2 m/sec, the gas concentrations measured at each point P ₁ , P ₂ , P ₃ are calculated as C ₁ , C ₂ ,
Assuming that C ₃ (C ₁ > C ₂ > C ₃ ), first identify the point P ₁ with the highest gas concentration among these points, and then identify this highest gas concentration point P ₁ and the other two points P ₂ , _P3
Find the virtual leakage sources Q ₁ and Q ₂ between To find the virtual leak source Q ₁ between points P ₁ and _{P 2} , find the distance L ₁ between points P ₁ and P ₂ , and
If the distance from P ₁ to the virtual leakage source Q _{1 is X 1 ,} then C ₁ ∝X ₁ −B→X∝ ₁ C ₁ ^-1/B C ₂ ∝(L−X ₁ ) ^−B → ₁ )∝C ₂ ^- 1/B ∴X ₁ : (L-X ₁ ) = C ₁ ^-1/B : C ₂ ^-1/B = 1/C ₁ ^1/B : 1/C ₂ ^1/B = C ₂ ^1/B : C ₁ ^1/B Therefore, X ₁ is determined from the relationship: X ₁ :(L−X ₁ )=C ₂ ^1/B :C ₁ ^1/B (1A). After finding the virtual leak source Q ₁ in this way, a perpendicular line is drawn that passes through the virtual leak source Q ₁ and is orthogonal to the straight line connecting the points P ₁ and P ₂ . Similarly, to find the virtual leak source Q ₂ between points P ₁ to _{P 3} , find the distance L ₂ between points P ₁ and P ₃ , and then calculate the distance from point P ₁ to the virtual leak source Q _2.
As X ₂ , find X ₂ from the relationship: X ₂ :(L ₂ −X ₂ )=C ₃ ^1/B :C ₁ ^1/B . After finding the virtual leak source Q ₂ in this way, a perpendicular line is drawn that passes through the virtual leak source Q ₂ and is orthogonal to the straight line connecting the points P ₁ and P ₃ . By this, find the position Q where both perpendicular lines intersect,
This is assumed to be the leak source. Here, strictly speaking, a leak source is a point that satisfies both formula (1A) and formula (1B), and such a point is the locus of formula (1A) (a curve orthogonal to the virtual leak source Q ₁ ). and the trajectory of equation (1B) (virtual leakage source Q ₂
(curve perpendicular to ). However, ∠
If the leakage sources are close to the straight lines P ₂ P ₁ and P ₁ P ₃ , such as when P ₂ P ₁ P ₃ is an acute angle, the points that satisfy both Equation (1A) and Equation (1B) are each virtual leakage source Q ₁ ,
It can be approximated as the intersection of perpendicular lines drawn from Q ₂ , making estimation easier and faster. Therefore, in this detection method, the source of the leak can be located by measuring the gas concentration at at least three points within the area where the leaked gas is spreading, and by determining the distances from the highest gas concentration point to the other two points. Since it can be estimated, the leak source can be searched for quickly and easily. In addition, in this detection method, when determining the distances X ₁ and X ₂ to the virtual leak sources Q ₁ and Q ₂ , the highest gas concentration point P ₁ was used as the reference point, but the reference point may also be two other points. . The detection method explained above assumes no wind or near no wind, so if the wind speed is at a predetermined value or
For example, it is difficult to accurately search for the source of leakage when the velocity is 2 m/sec or more. The second invention makes it possible to search under such conditions. Next, an embodiment of the detection method of the second invention will be described in the second embodiment.
The diagram will be explained. In this detection method, the average gas concentration in at least three different regions is measured within the area where the leaked gas is diffused. In this case, the gas concentration at each intersection of a predetermined matrix may be measured, and the range surrounded by each of these intersections may be regarded as one region, and the average gas concentration in that region may be calculated. The gas concentration may be measured at one or several points in each of three or more regions and averaged to calculate the average gas concentration in each region. Next, from among these average gas concentration data groups, 3 that have the highest average gas concentration and are arranged along the wind direction are selected.
For example, three areas A ₁ , A ₂ , and A ₃ are identified. In this case, since there are two measurement points P ₁₁ , P ₁₂ , P ₃₁ , and P ₃₂ in areas A ₁ and A ₃ , these measured gas concentrations are averaged to obtain the concentration, but in area A ₂ , 1
Since there is only one measurement point _P21 , the measured gas concentration at this point is taken as the average gas concentration in area _A2 . Next, calculate the average gas concentration among these three regions A ₁ , A ₂ , and A ₃ (here, ₂ > ₁ > ₃ ).
Identify the area A ₂ with the highest value and the area A ₁ with the next highest value. Here, the leaked gas is blown away by the wind, and the leak source is estimated to be near the highest average gas concentration region _A2 . At this time, if the wind is strong, the leak source Q is estimated to be on the windward side of area _A2 , that is, on the area _A3 side. On the other hand, if the wind is weak, the leak source Q is in area A ₂
In addition to the windward side of area A ₂ , the leeward side of area A ₁
It is also presumed to be on the side (see Figure 2). Of these, for the leak source Q on the area A ₁ side,
Find the distance L between the highest average gas concentration area A ₂ and the next highest average gas concentration area A ₁ , and let the distance between area A ₂ and the estimated leak source Q be X, then from area A ₁ to the estimated leak source Q. The distance is (L-X), so ₁ ∝(L-X) ^- _B →(L-X)∝ ₁ ^-1/B ₂ ∝X ^-B →X∝ ₂ ^-1/B ∴X: ( L-X) = ₂ ^-1/B : ₁ ^-1/B = _1/2 ^1/B : _1/1 ^1/B = ₁ ^1/B : ₂ ^1/B Therefore, X: (L-X) = ₁ ^1/B : ₂ ^1/B ...(2A) Find the distance X from the relationship, and determine the leak source Q from this X. On the other hand, for the leak source Q on the area A ₃ side, the highest average gas concentration area A ₂ and then the average gas concentration area A ₁
Find the distance L from area A ₂ to the estimated leak source Q, and let the distance between area A 2 and the estimated leak source Q be X. Since the distance from area A ₁ to the estimated leak source Q is (L + X), ₁ ∝ (L + X) ^{-B →} _{( L} ⁺ _{_} ^_ _{_} ^_ _{_} ^_ _{_} ^_ / ₁ ^1/B = ₁ ^1/B : ₂ ^1/B Therefore, X: (L + X) = ₁ ^1/B : ₂ ^1/B ... (2B) From the relationship, find the distance Determine the source Q. In this way, the location of the leak source Q can be determined by employing any of the methods described above depending on conditions such as wind speed. Therefore, in this detection method, by measuring the average gas concentration in at least three regions and determining the distance from the highest gas concentration region to the next highest average gas concentration region, leakage can be detected even if the wind speed is higher than a predetermined value. Since the leak source can be estimated, the leak source can be searched for quickly and easily. In addition, in this detection method, the average gas concentration in at least three or more regions is determined, but
The gas concentration may be measured at three different points. Next, a detection system that automatically searches for gas leak sources in chemical plant facilities using these detection methods will be described with reference to FIG. In the figure, 11 ₁ to 11 _o are multiple gas detectors installed at different locations within the chemical plant facility, and 12 is an anemometer that measures the wind direction and wind speed within the chemical plant facility. The detected signal is converted into a digital signal by an A/D converter 13, and then taken into a central processing unit (hereinafter referred to as CPU) 15 via an interface circuit 14. After storing various constants entered from the keyboard 16 in the storage device 17, the CPU calculates the source of leakage based on the data given through the interface circuit 14, and sends the results to the CRT display device 18 and printer 19. Output. That is, as shown in the flowchart of FIG. 4, wind speed and direction data from the anemometer 12 and gas concentration data from the gas detectors 11 ₁ to 11 _o are acquired at predetermined sample intervals, and then these are averaged. After that, it is determined whether the wind speed is less than 2 m/sec. Here, if the wind speed is less than 2 m/sec, the method of leak source estimation processing () (which is the same as the detection method described in Fig. 1 above, but specifically,
After estimating the leakage source using the flowchart shown in the figure, the leakage source is outputted to the CRT display device 18 or printer 19. In addition, when the wind speed is 2 m/sec or more, the leak source estimation processing method () (same as the detection method described in Figure 2 above, but specifically refer to the flowchart in Figure 6) is used. After estimating the leak source, it is output to the CRT display device 18 or printer 19. Next, we will discuss an example in which the source of a gas leak in a chemical plant facility was actually estimated using this system. FIG. 7 shows an ethylene production device. In the figure, the raw material from the previous step is supplied to a distillation column 22 through a flow rate regulating valve 21. Distillation column 22
The product, ie, ethylene, extracted from the top of the column is sent to a receiver tank 24 through a condenser 23. The products stored in the receiver tank 24 are
The liquid is refluxed to the top of the distillation column 22 by the reflux pump 25 through a flow rate adjustment valve 27 whose opening is adjusted according to a command from the top temperature detector 26, while the liquid level detector 28 of the tank 24 The liquid is sent to the storage tank through a flow rate adjustment valve 29 whose opening degree is adjusted according to a command from the flow control valve 29. Further, the by-product, that is, ethane extracted from the bottom of the distillation column 22 passes through a reboiler 30, a vaporizer 31, and a super heater 32, and then passes through a liquid level detector 3 of the distillation column 22.
The liquid is discharged through a flow rate regulating valve 34 whose opening degree is adjusted by 3. Now, in the ethylene rectification column shown in the figure, liquefied ethylene gas suddenly leaked from the mechanical seal of the reflux pump 25.
The weather conditions at that time were that the wind direction was eastward and the wind speed was 1
m/sec, and the temperature was 19℃. In addition, the reflux pump 25, which is the leak source, has a suction pressure of 10 kg/cm ² G,
Since the discharge pressure is 16 kg/cm ² G and the fluid being handled is liquid ethylene, the ethylene ejected from the mechanical seal immediately evaporates and diffuses, and 3 minutes after the leak occurs, the reflux pump is released as shown in Figure 8. Centered on 25, 20m west, 11m east, north and south.
It spread to 12m. A gas detector 11 is installed in the area where the leaked gas has spread.
₁₁ , 11 ₁₂ , and 11 ₁₃ were arranged, and the respective detected gas concentrations were as follows. Detector 11 ₁₂ →25LEL% Detector 11 ₁₁ →32LEL% Detector 11 ₁₃ →49LEL% In this detection system, first, detector 11 ₁₁ ~ 1
1 ₁₃ and the signals detected by the anemometer 12 are converted into digital signals by the A/D converter 13 and then taken into the central processing unit (hereinafter referred to as CPU) 15 through the interface circuit 14. . After averaging these data, the CPU 15 determines whether the wind speed is less than 2 m/sec. In this case, since the wind speed is less than 2 m/sec, the leak source is estimated by the leak source estimation process (). In the leak source estimation process ( ), first, the point of the highest gas concentration among the gas concentrations measured by the three detectors 11 ₁₁ to 11 ₁₃ , that is, the position of the detector 11 ₁₃ is specified. Subsequently, a virtual leak source Q ₁ between the detectors 11 ₁₃ and 11 ₁₁ is determined. Here, the detector 11
Since the distance L ₁ between ₁₃ and 11 ₁₁ is 18 m, the measured concentration of this and detectors 11 ₁₃ and 11 ₁₁ can be calculated using the above formula (1A).
By substituting , X ₁ is found, X ₁ = 7.8m. However, the concentration decay constant B is
It is 0.75. As a result, the sensor 11 _{11 , 11 13} passes through the virtual leak source Q ₁ which is X ₁ away from the detector _{11 13} .
Find the perpendicular line that is perpendicular to the straight line connecting the two. Next, the virtual leak source Q ₂ between the detectors 11 ₁₃ and 11 ₁₂ is determined. Here, the detectors 11 ₁₃ ,
Since the distance L ₂ between the detectors 11 ₁₂ is 24 m, when X 2 is obtained by substituting this and the measured concentration of the detectors 11 ₁₃ and 11 ₁₂ into the above equation (1B), _{X 2 =} 9.1 m is obtained.
However, the concentration decay constant B is the same as above. This allows the virtual leak source to be located X ₂ away from the detector 11 ₁₃ .
A perpendicular line passing through Q ₂ and perpendicular to the straight line connecting the detectors 11 ₁₃ and 11 ₁₂ is found (see Figure 9). Finally, after the positions where both perpendicular lines intersect with each other are determined, these data are output to the CRT display device 18. As shown in FIG. 10, the estimated result was slightly to the northwest of the actual leakage location, but the result is generally satisfactory. Therefore, this system has the advantage of automatically detecting leak sources under all weather conditions. Therefore, it is effective as an emergency countermeasure for chemical plants. In addition, in this system, gas detectors are arranged in a predetermined matrix (for example, with an interval of 20 m).
By arranging the leakage source at each intersection, the leak source can be detected with higher accuracy. [Effects of the Invention] As described above, according to the present invention, it is possible to provide a gas leak source detection method that can quickly and accurately search for a leak source.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an embodiment of the first invention;
Fig. 2 is an explanatory diagram showing an embodiment of the second invention, Fig. 3 is a block diagram showing a detection system, Figs. 4 to 6 are flowcharts, and Fig. 7 is a system showing an ethylene rectification column. Figure 8 is a plan view of the plant facility, Figure 9 is a diagram showing the leak source estimation results, and Figure 10 is a diagram showing the estimation results of leak sources.
The figure is a diagram showing an estimated position of a leak source and an actual leak source position.

Claims (1)

[Claims] 1. A method for detecting a gas leak source in windless or near windless conditions, which detects the gas concentration at at least three different points within an area where leaked gas is diffused, and Identify the three points with the highest gas concentration from the concentration data group, find each virtual leak source between this highest gas concentration point and the other two points, and find the highest gas concentration point that passes through each of these virtual leak sources and A method for detecting a gas leak source, comprising: determining a position where perpendicular lines intersect with each other perpendicular to a straight line connecting a gas concentration point and two other points, and estimating this position as a leak source. 2. In claim 1, the virtual leak source is defined by the distance between two points sandwiching the virtual leak source and the distance from either point to the virtual leak source,
A method for detecting a gas leak source, characterized in that the gas leakage source is determined by multiplying the gas concentration at each point by a concentration decay constant. 3. A method for detecting a gas leak source in the presence of wind, which detects the gas concentration at at least three or more different points or the average gas concentration at at least three or more different areas within an area where the leaked gas is diffused, From among these gas concentration data groups or average gas concentration data groups, three points or areas with the highest gas concentrations and lined up along the wind direction are identified, and the highest gas concentration points or areas and the second highest gas concentration are identified. Find the distance to the point or area, and calculate this distance as L, the distance between the highest gas concentration point or area and the estimated leak source as X, the gas concentration at the highest gas concentration point or area as _C1 , and the second gas concentration point or area. When the gas concentration in the region is C ₂ and the concentration decay constant is B, then X: (L-X) = C ₁ ^1/B : C _{2 1} ^{/B and} A method for detecting a gas leak source, characterized in that the distance X is determined from at least one formula of: C ₂ ^1/B and the leak source is estimated from this X.