JP4031695B2 - Leak detector - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for detecting liquid leakage from a condenser or the like of a thermal power generation facility, for example, a device through which seawater flows.
[0002]
[Prior art]
Conventionally, in a thermal power generation facility or the like, steam generated in a boiler is cooled and condensed by a condenser and circulated and used as boiler water (pure water). Here, the seawater for cooling flows in the condenser, but when a crack or the like occurs in the condenser (especially its heat exchanger), the seawater leaks from it and enters the boiler water condensed outside, Boiler water is mixed with salt and corrodes various pipes. Therefore, various seawater leakage detection devices have been developed to check for seawater leakage from the condenser (see, for example, Patent Document 1).
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 2001-141596
[Problems to be solved by the invention]
However, in the case of the above-described prior art, since the boiler water condensed at the lower part of the condenser is collected and liquid analysis is performed, the problem is that the leaked seawater is significantly diluted with the boiler water and the detection sensitivity is reduced accordingly. is there. In addition, the actual seawater leak is caused by a part of the condenser cracking, but in the case of the above technology, it is impossible to specify which part of the condenser is leaking, and it takes time to deal with it. There was also.
[0005]
The present invention has been made to solve the above problems, and an object of the present invention is to provide a leak detection device capable of specifying the leak position of a target device for liquid leak detection.
[0007]
[Means for solving problems]
In order to achieve the above-described object, a leak detection device according to claim 1 is installed below a target device for liquid leak detection and is arranged in parallel with each other, and the two metal wires. Leak position specifying means for specifying the leak position of the target device based on the correlation between the time until the current flows between each metal wire and the length of the metal wire after applying the pulse voltage between It is characterized by comprising.
In this way, the leakage position is based on the correlation between the time from the application of the pulse voltage until the current flows and the length of the metal wire because the liquid leaks between the metal wires and becomes conductive. Can be identified.
[0008]
The leak detection device according to claim 2, wherein the target device of the liquid leak detection has a large number of tubes arranged in parallel in one direction and is on a plane intersecting the one direction and around the tube. Correlation between two metal lines arranged on the surface and the time from when a pulse voltage is applied between the two metal lines until a current flows between the metal lines and the length of the metal line And a leak position specifying means for specifying a leak position of the target device, wherein a leaked pipe is specified from the target device by the leak position.
In this way, the leakage position is based on the correlation between the time from the application of the pulse voltage until the current flows and the length of the metal wire because the liquid leaks between the metal wires and becomes conductive. Can be identified. In addition, it is possible to identify the pipe in which the leak has occurred. For example, a countermeasure can be quickly taken by placing a blind plug in the pipe.
[0009]
A leak detection apparatus according to another aspect of the present invention includes an optical fiber installed below a target device for liquid leak detection, and scattered light detected at the end when pulse light is incident on the end of the optical fiber. Leakage position specifying means for specifying the leak position of the target device based on a change in strength over time is provided.
In this way, when the leaked liquid adheres to the optical fiber, the light leaks to the outside and the scattered light intensity changes, so the length of the optical fiber corresponding to the time when this change has occurred can be obtained. The leak position can be specified.
[0010]
In the leak detection device according to another aspect of the present invention, when the target device for liquid leak detection is formed by arranging a large number of pipes in parallel in one direction, the leak detection apparatus is on a plane intersecting the one direction. An optical fiber disposed around the tube, and a tube in which leakage has occurred among the target devices based on a temporal change in scattered light intensity detected at the end of the optical fiber when pulse light is incident on the end of the optical fiber And a leak position specifying means for specifying.
In this way, when the leaked liquid adheres to the optical fiber, the light leaks to the outside and the scattered light intensity changes, so the length of the optical fiber corresponding to the time when this change has occurred can be obtained. The leak position can be specified. In addition, it is possible to identify the pipe in which the leak has occurred. For example, a countermeasure can be quickly taken by placing a blind plug in the pipe.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, each embodiment of the leak detection apparatus according to the present invention will be described with reference to the drawings.
[0012]
FIG. 1 shows a configuration of a leak detection apparatus according to the first embodiment. In this figure, the leak detection device is a measuring machine that measures electrical conductivity when a voltage is applied between the metal wires 2A to 2H, 3A, and 3B installed below the condenser 100 and a predetermined metal wire. 20, switching circuits 21, 22 for switching the metal wires connected to the measuring device 20, an outer frame 25 for stretching each metal wire, and controlling the measuring device 20, and the electric conductivity value from the measuring device 20 And a computer (leak position specifying means) 10 for specifying the seawater leak position of the condenser 100 based on the above.
[0013]
The condenser 100 is a unit in which a structure in which a thin tube extending in the longitudinal direction is bent 180 degrees in a direction perpendicular to the same on a single plane and then folded back in the longitudinal direction is defined as one unit. 1 has a structure in which a large number of layers are stacked in the vertical direction. And the cooling seawater which flowed in from the entrance side of a thin tube cools the boiler vapor | steam sprayed on the outer side of the condenser 100 to make condensed water, and flows out from the exit side of a thin tube. Hereinafter, the longitudinal direction of the condenser 100 is referred to as “first direction”, and the direction perpendicular to the longitudinal direction is referred to as “second direction”.
[0014]
The metal wires 2 </ b> A to 2 </ b> H are arranged in parallel with the second direction, and the end portions of the metal wires 2 </ b> A to 2 </ b> H are fixed to the inner surface in the longitudinal direction of the outer frame 25. The metal wires 3A and 3B are arranged in parallel to the first direction, and the end portions of the metal wires 3A and 3B are fixed to the inner surface of the outer frame 25 in the short direction. The metal wires 2A to 2H and the metal wires 3A and 3B are on different planes. In this way, the metal wires 2A to 2H, 3A, and 3B are arranged in a net shape in the outer frame 25, and all the metal wires are separated from each other. The outer frame 25 is installed above the condensed water recovery tank below the condenser 100.
[0015]
Switching circuits 21 and 22 are arranged on two adjacent outer surfaces of the outer frame 25 to switch the metal wire connected to the measuring machine 20. That is, the switching circuit 21 connects any one of the metal wires 3A and 3B to the measuring device 20, and the switching circuit 22 connects any one of the metal wires 2A to 2H to the measuring device 20. Thereby, for example, the metal wires 2 </ b> A and 3 </ b> A are connected to the measuring machine 20, and the electrical conductivity when a voltage is applied between these metal wires is measured.
[0016]
Next, a method for measuring electrical conductivity will be described. First, consider the case where the metal wires 2A and 3A are connected to the measuring machine 20, respectively. In this case, the measuring device 20 applies a voltage between the metal wires 2A and 3A to measure the electrical conductivity. However, since the metal wires are separated from each other in the intersection region S, no current flows and the electrical conductivity is measured. The degree becomes smaller. On the other hand, consider a case where the metal wires 2D and 3A are connected to the measuring machine 20 by the switching circuits 21 and 22, respectively. Here, when the seawater leakage of the condenser 100 occurs above the intersection region T between the metal wires 2D and 3A, the seawater adheres to the intersection region T and the metal wires become conductive. Accordingly, current flows between the metal wires, and the electrical conductivity increases. Thus, by scanning each metal line by the switching circuits 21 and 22 and specifying the metal line connected to the measuring instrument 20 when the electrical conductivity becomes large, from the intersection position of each metal line. The leak position can be specified.
[0017]
Next, the configuration of the leak detection apparatus according to the second embodiment will be described with reference to FIG. In this figure, the leak detection device includes two metal wires 4A and 4B installed below the condenser 100, a measuring device 30 that measures current when a pulse voltage is applied between the metal wires, A computer (leak position specifying means) 10A that controls the measuring machine 30 and specifies the seawater leakage position of the condenser 100 based on the current value from the measuring machine is provided. Since the condenser 100 is the same as that used in the first embodiment, the description thereof is omitted.
[0018]
The metal wires 4A and 4B are arranged parallel to each other while meandering below the condenser 100 while being meandering. One end of each of the metal wires 4A and 4B is connected to the measuring machine 30, and the current when a pulse voltage is applied between these metal wires is measured.
[0019]
Next, a method for measuring current will be described. Here, it is assumed that leaked seawater adheres to the predetermined positions X and Y of the metal wires 4A and 4B, respectively, and the metal wires 4A and 4B are electrically connected at this place. Further, it is assumed that the lengths of the metal wires 4A and 4B from the connection portion with the measuring machine 30 to the end Z are known.
[0020]
FIG. 4 shows a current-time graph measured by the measuring instrument 30 when the time for applying the pulse voltage is zero. In this figure, when leaking seawater adheres between each metal wire and conducts, current flows through that portion, but the current path becomes shorter as the conducting portion is closer to the start point, so the current starts from time 0. The time until it starts flowing is also shortened. In this figure, the current generation time is shorter for X, which is closer to the starting point, than for Y. Accordingly, the current generation time t0 when the terminal Z is conductive and the length of the metal wire from the start point to Z are obtained in advance, and the current generation time t1 at X is measured, so that the distance from the start point to X is determined. Is obtained by proportional calculation, and as a result, the leak position X can be specified.
[0021]
Next, the configuration of the leak detection apparatus according to the third embodiment will be described with reference to FIG. In this figure, the leak detection device is installed below the condenser 100, one end Q is an open end, and pulse light is incident on the end face of the other end O of the optical fiber 5, and the return scattering at that time. A measuring device 40 that detects the light intensity, and a computer (leak position specifying means) 10B that controls the measuring device 40 and specifies the seawater leakage position of the condenser 100 based on the scattered light intensity from the measuring machine 20 are provided. . Since the condenser 100 is the same as that used in the first embodiment, the description thereof is omitted. The optical fiber 5 is disposed while meandering below the condenser 100.
[0022]
Next, a method for measuring the scattered light intensity will be described. Here, it is assumed that leaked seawater adheres to a predetermined position P of the optical fiber 5. Further, it is assumed that the length of the optical fiber 5 from the end O where the pulse light is incident from the measuring device 40 to the open end Q is known.
[0023]
FIG. 6 shows a scattered light intensity-time graph measured by the measuring instrument 40 when the time when the pulsed light is incident is zero. Here, the general properties of the scattered light will be described. The scattered light is the light that returns to the predetermined position in the optical fiber, and it takes time to return as the scattering position becomes farther. The light loss is caused by the length of the path and the intensity is also reduced. Accordingly, in FIG. 6, in the normal state, the scattered light intensity decreases as time elapses. Note that the intensity peak occurs at time t0 due to scattering from the open end Q.
[0024]
On the other hand, when seawater (water droplets) adheres to the outside of the optical fiber, light traveling in the optical fiber leaks outside due to the influence of the refractive index of water. Accordingly, the intensity of the scattered light is also reduced at the water drop attachment position P. That is, the intensity of the scattered light that enters from the end O and returns at the position P rapidly decreases as indicated by the dotted line in the figure. Therefore, the time t1 when the strength suddenly decreased is measured, and the following formula (c × t1) / 2 (1)
By substituting into, the distance from the starting point O to the adhesion position P is obtained, and as a result, the leakage position P can be specified. Note that c in the equation (1) is the speed of light in the core of the optical fiber, and the half term in the equation (1) takes into consideration that the incident light is a reciprocating path that travels back through the optical fiber. is there.
[0025]
When an optical fiber is used, reflected light from the fiber end face can be measured instead of the scattered light. In this case, as shown in FIG. 7, a plurality of optical fibers are branched from one main optical fiber, and the ends of the branched optical fibers are disposed at various locations below the condenser 100 (FIG. 7 (a)). . The pulse light incident on the main optical fiber from the measuring device is reflected and returned at the end face of each branch optical fiber, and the reflected light intensity depends on the distance between each end and the incident end face of the main optical fiber ( It becomes a peak (according to the time from the pulse incidence) (FIG. 7B). Therefore, if leaking seawater adheres to the end of one of the branched optical fibers, the intensity of the peak is lowered, thereby enabling the location of the leak to be specified.
[0026]
Next, the configuration of the leak detection apparatus according to the fourth embodiment will be described with reference to FIG. In this figure, the leak detection apparatus has substantially the same configuration as that of the second embodiment, and controls two metal wires 4A and 4B, the measuring instrument 30, and the measuring instrument 30 and performs measurement. And a computer (leak position specifying means) 10C that specifies the seawater leak position of the condenser 100 based on the current value from the machine. Since the metal wires 4A and 4B, the measuring device 30, and the condenser 100 are the same as those used in the second embodiment, description thereof is omitted.
[0027]
In the present embodiment, the arrangement of the metal wires 4A and 4B is different from that of the second embodiment. That is, when viewed from the longitudinal direction of the condenser 100, a large number of thin tubes 101 to 112 are disposed in parallel to the longitudinal direction, but the metal wires 4A and 4B are disposed on a plane R intersecting the longitudinal direction. . Further, the metal wires 4A and 4B are arranged so as to surround each of the thin tubes 101 to 112, respectively. For convenience, the metal wires 4A and 4B are drawn as one line.
[0028]
FIG. 9 is a layout view when the metal wires 4A and 4B are viewed from the surface R direction. In this figure, the metal wires 4A and 4B are arranged, for example, in contact with the outer periphery of the narrow tube 107 about a half turn, and in contact with the outer periphery of the adjacent thin tube 108 about a half turn, and thereafter contact the outer periphery of each thin tube. . Here, when seawater leaks above the narrow tube 109, the metal wires 4A and 4B at the position V immediately above are conducted, so that the leak position V is set in the same manner as already described in the second embodiment. Can be identified. And in this embodiment, when the connection site | part with the measuring machine 30 of metal wire 4A, 4B is made into the starting point, the distance of metal wire 4A, 4B and the positional relationship with each thin tube are matched previously. For example, 109 is associated with the thin tube in contact with the metal wire at position V. In this way, if the leak position V can be specified, the pipe 109 in which the leak has occurred can be specified. For example, a countermeasure can be taken quickly by placing a blind plug in the pipe. Preferably, the surface R is near the end of the thin tube. This is because leakage tends to occur particularly at the bent portion of the narrow tube end.
[0029]
In addition to the above-described metal wires 4A and 4B, the optical fiber 5 described in the third embodiment is used and similarly arranged around each thin tube, it is possible to specify the tube in which leakage has occurred.
[0030]
Further, in each of the above embodiments, after the computer specifies the leak position, it is possible to notify the worker of the leak state by displaying the fact or the like, and to make it a material for determining whether or not to stop the boiler. . In this case, it is preferable to display the degree of leakage or the like.
[0031]
The present invention is not limited to the above-described embodiment. The target device for leak detection is not limited to a condenser, but may be various heat exchangers, and the leaking fluid is not limited to seawater. Anything can be used.
[0032]
Furthermore, it is also possible to combine the leak detection apparatus according to the first to third embodiments and the leak detection apparatus according to the fourth embodiment. In this way, the leak position of the target device can be specified from two directions, and the leak position can be specified in more detail.
[0033]
【The invention's effect】
As described above, according to the present invention, it is possible to specify the leakage position of the target device for liquid leakage detection.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a leak detection apparatus according to a first embodiment of the present invention.
FIG. 2 is a diagram showing a method for measuring electrical conductivity.
FIG. 3 is a diagram showing a configuration of a leak detection apparatus according to a second embodiment of the present invention.
FIG. 4 is a diagram illustrating a method for measuring current.
FIG. 5 is a diagram showing a configuration of a leak detection apparatus according to a third embodiment of the present invention.
FIG. 6 is a diagram showing a method for measuring scattered light intensity.
FIGS. 7A and 7B show another aspect of the leak detection apparatus according to the third embodiment of the present invention, where FIG. 7A is a configuration diagram and FIG. 7B is a diagram showing a method for measuring reflected light intensity.
FIG. 8 is a diagram showing a configuration of a leak detection apparatus according to a fourth embodiment of the present invention.
9 is a view as seen from the direction of the surface R in FIG. 8;
[Explanation of symbols]
2A-2H Multiple metal lines 3A, 3B (arranged in the first direction) Multiple metal lines 4A, 4B (arranged in the second direction) Two metal lines 5 Optical fiber 10, 10A-10C Computer ( Leakage location identification means)
100 Condenser (target device for leak detection)
101 to 112 Many pipes R A plane intersecting one direction

Claims (2)

Two metal wires installed below the target device for liquid leakage detection and arranged parallel to each other;
Based on the correlation between the time from when a pulse voltage is applied between the two metal wires until the current flows between the metal wires and the length of the metal wire, the leakage position of the target device is determined. A leak detection device comprising: a leak position specifying means for specifying. When the target device for liquid leak detection has many pipes arranged in parallel in one direction,
Two metal wires arranged on a plane intersecting the one direction and around the tube;
Based on the correlation between the time from when a pulse voltage is applied between the two metal wires until the current flows between the metal wires and the length of the metal wire, the leakage position of the target device is determined. And a leakage position specifying means for specifying,
The leak detection apparatus characterized by specifying the pipe | tube in which the leak generate | occur | produced among the said object apparatuses with the said leak position.

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