JP2003121290A - Leakage detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quickly correctly determine occurrence of leakage at a leakage risk position such as a flange or the like connected to piping for running a gas and a liquid. SOLUTION: This leakage detector comprises a collector disposed at a measurement object part, a temperature sensor attached to the collector, a temperature regulator, a wattmeter or an ammeter attached to a heater, and a leakage determination device. While stabilizing the temperature in the collector, the occurrence of the leakage is determined by the variation ΔW of the wattmeter exceeding a predetermined threshold by the leakage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a leak detecting device, and more particularly to a leak detecting device at a portion having a high leak potential such as a thermal power plant, a nuclear power plant, a chemical plant, a pipeline or the like.

[0002]

2. Description of the Related Art A pressure drop method is known as one of conventional leak detection methods. The pressure drop method is a method in which a pressure gauge is installed at a location where there is a possibility of leakage, and a phenomenon in which the pressure decreases due to gas leakage is captured to detect the leakage.

FIG. 9 shows an example of measurement by a conventional pressure drop method, taking a nuclear power plant as an example.

For example, in order to detect the leakage of the fluid 11 flowing from the nuclear reactor 81, a Bourdon tube type pressure gauge 91,
Install 92. Here, when a leak occurs near the pressure gauges 91 and 92 under the constant flow rate of the fluid 11 during operation, the indication value of the pressure gauge decreases, and the leak can be detected.

[0005]

In the above-mentioned pressure drop method of the prior art, since the pressure gauge is installed at the leakage risk point of interest, the leakage site is specified for an unspecified number of leakage risk points. In addition, there is a problem that a leak of about 20 cm ³ / s requires a detection time of 1 to 2 weeks, and the time required for leak detection becomes long. Furthermore, the substance to be leaked is limited to only gas.

An object of the present invention is to provide a leak detection device capable of detecting not only gas but also liquid as a leak target, and performing quick and accurate determination of leak occurrence, identification of leak location, and calculation of leak amount. Is to provide.

[0007]

SUMMARY OF THE INVENTION The above-mentioned object is to provide a collector for collecting a leaked substance from a dangerous leakage point, a heater and a temperature controller for adjusting the temperature in the collector constant, and a heater. This can be achieved by providing a wattmeter attached to the device and a leakage determination device that determines leakage.

The temperature adjuster adjusts the electric power of the heater in order to keep the temperature inside the collector constant, and the leakage determining device monitors the amount of change of the watt meter. If a leak occurs from a leaking danger point, the temperature regulator adjusts the electric power of the heater to keep the temperature inside the collector constant,
Since the electric power changes, the leakage determining device detects the leakage by catching the change in the electric power of the heater. In addition, the amount of leakage is calculated from the relationship between the amount of change in the watt meter and the amount of temperature change due to the temperature sensor leakage. Further, by using the optical fiber for the temperature sensor and the network and performing the leakage monitoring on the leakage dangerous spots scattered, it becomes possible to specify the leakage spot.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment of a leakage determination device according to the present invention will be described with reference to FIGS. (Embodiment 1) FIG. 1 is a block diagram for detecting leakage of a flange 61 connected to a pipe 62, for example. The leak detection device of the first embodiment is a watt meter 52 for measuring the electric power of the heater 58, a collector 53 for collecting the leaked material at the leakage danger point, and the temperature inside the collector 53 is adjusted to be constant. The temperature controller 57 and the temperature sensor 55, the leakage determination device 20 for determining leakage, and the computer 54. In addition, 59 in the figure
Is a power supply for supplying electric power to the heater 58.

The leak determination device 20 comprises a data collection unit 21, a wattmeter memory unit 22, a wattmeter operation unit 23, a wattmeter comparison unit 29, and a leak determination unit 24.

First, the temperature controller 57 installs a temperature sensor 55 such as a thermocouple, an optical fiber and a platinum resistance in the collector 53, and a feedback signal 58 from the temperature sensor 55 keeps the temperature inside the collector 53 constant. The electric power of the heater 58 is adjusted so as to be adjusted.

Next, when the fluid 11 leaks in the collector 53, the temperature sensor 55 detects the temperature change, and the feedback signal 58 causes the temperature controller 57 to control the temperature in the collector 53. The electric power of the heater 58 is adjusted so as to be constant.

Further, a change in the electric power of the heater 58 is monitored by the watt meter 52, and the amount of the change is captured to detect the leak.

The determination of leakage detection is performed as follows. The data collection unit 21 of the leakage determination device 20 takes in the power value of the watt meter 52 and stores it in the watt meter memory unit 22. After that, the watt meter computing unit 23 subtracts the present watt meter instruction value W1 from the instruction value W2 stored in the watt meter memory unit 22 a predetermined time before and calculates ΔW. The watt meter comparison unit 29 compares the power change amount ΔW calculated by the watt meter calculation unit 23 with the threshold value 28 ΔW (limit), and the leakage determination unit 2
In 4, when ΔW> ΔW (limit), it is determined that leakage has occurred, and when ΔW <ΔW (limit), it is determined that leakage has not occurred. The result is displayed on the computer 54 or a buzzer is sounded to notify the occurrence of leakage.

According to the present invention, it is possible to detect the leakage from the leakage dangerous place by installing the collector at the leakage dangerous place and providing the leakage judging device. It should be noted that leakage can be detected not only for gas but also for liquid. Further, although the leak detection is performed by using the heater power, the same detection can be performed by using the heater current. (Embodiment 2) In FIG. 2, a leak amount calculation unit 25, a database 27, a temperature memory unit 30, and a temperature calculation unit 31 are added to the leak determination device 20 of FIG. The other reference numerals are the same as those in FIG. Also,
The data of the temperature sensor 55 is input to the data collection unit 21 of the leakage determination device 20. The database 27 is a table that stores the relationship between the temperature conversion amount ΔT of the temperature sensor 55 and the power change ΔW obtained by experiments or the like. FIG. 3 shows the relationship between ΔT and ΔW and the leakage amount ΔF per unit time obtained from the experimental results.

According to the method described in the first embodiment, the leakage determination unit 24
When it is determined that the leakage has occurred, the database 27 determines that the power change amount ΔW of the watt meter 52 and the temperature change amount ΔT of the temperature sensor 55.
3, the horizontal axis f (ΔT, ΔW) of FIG.
Pass a value to. The relational expression of f (ΔT, ΔW) is expressed by f (ΔT, ΔW) = ΔW ^α × ΔT ^β (α and β are constants) --- (1). The constants α and β are corrected by considering parameters such as the shape of the collector, the material of the leakage target location, the thermal conductivity, and the temperature of the leakage target location, and are values obtained by element tests and the like.

The leakage amount calculation unit 25 substitutes the value obtained from the relational expression (1) for ΔT and ΔW acquired from the database 27 into the following expression (2) to obtain the leakage amount ΔF per unit time.

ΔF = g (f (ΔT, ΔW)) --- (2) The leakage occurrence detection duration t of the leakage determination device 20 and the ΔF calculated from the equations (1) and (2) are used to obtain the equation (3). The absolute amount F of leakage can be calculated at.

F = ΔF × t --- (3) The constants α and β in the equations (1) and (2) are stored in the leakage amount calculator 25 and the database 27 from the computer 54. Further, the relation of the leakage amount per unit time was obtained from the electric power and the temperature, but the leakage amount can be obtained from the relation of the electric current and the temperature.

According to the present invention, by providing the relationship between the temperature change amount, the power change amount, and the leakage amount per unit time obtained in the experiment in the leakage amount calculation unit 25 and the database 27, the leakage from the leakage risk location The quantity can be estimated. (Embodiment 3) FIG. 4 is a view showing an embodiment in which another temperature sensor (for example, an optical fiber) 56 is installed around the flange portion 62. The optical fiber 56 is installed in the vicinity of the risk of leakage. The signal of the installed optical fiber 56 is input to the leakage determination device 20.

FIG. 5 shows the inside of the leakage determination device 20 of the third embodiment. In the leakage determination device 20 of the third exemplary embodiment, the leakage determination device 20 shown in FIG.
A temperature comparator 33 and a threshold 33 are added. The temperature memory unit 30 stores the signal of the optical fiber 56, and the temperature calculation unit 31 subtracts it from the temperature of a predetermined time before to obtain the change amount ΔT. In the temperature comparison unit 32, ΔT 'and the threshold value 33 of the temperature change amount before the predetermined time 33
In comparison with ΔT (limit), if ΔT> ΔT ′ (limit), the leakage determination unit 24 determines that leakage has occurred.

In the first embodiment, whether or not a leak has occurred is determined using only the power change amount ΔW of the watt meter 52, but in the present embodiment, the power change amount Δ of the watt meter 52 is determined.
When either W or the temperature change amount ΔT of the optical fiber 56 exceeds the threshold value, it is determined that leakage has occurred. In particular, if the temperature locally leaks from the flange, the temperature change amount ΔT quickly exceeds the threshold value rather than the power change amount ΔW, so that the leak can be detected quickly.

According to the present invention, the watt meter 52 and the change amount of the optical fiber 56 installed in the vicinity of the leak point are used in combination, so that the leak can be detected quickly against the local leak. In the third embodiment, the optical fiber is installed in the vicinity of the leak point, but it can be realized by installing the thermocouple in the circumferential direction of the flange. (Embodiment 4) FIG. 6 is a block diagram showing Embodiment 4 in which the leakage amount is calculated using, for example, the optical fiber 56.
The leak determination device 20 of FIG.
27 and database 34 are added. The optical fiber 56 was installed around the flange 62 as in FIG.

FIG. 7 is a temperature sensor obtained from element tests and the like.
The relationship between the temperature change amount ΔT of 55, the temperature change amount ΔT of the optical fiber 56, and the power change amount ΔW of the watt meter 52 is shown.

The database 27 stores the constants of the above equation (1) showing the relationship between the temperature change amount ΔT of the temperature sensor 55 and the power change amount ΔW of the watt meter 52. In addition, the database 34 stores the temperature change amount ΔT of the optical fiber 56 and the watt meter 5
The constant of the equation (1) indicating the relationship of the power variation amount ΔW of 2 is stored. Further, the leakage amount calculation unit 25 stores the constant of the expression (2).

By the method described in the third embodiment, the leakage determination unit 24
If it is determined that the leakage has occurred, the database 27 of the temperature sensor 55 and the database 34 of the optical fiber 56 are activated. The temperature change amount ΔT of the temperature sensor 55, the temperature change amount ΔT of the optical fiber 56, and the power change amount ΔW of the watt meter 52 are respectively
Inputting to the database 27 and the database 34, the horizontal axis f (temperature change amount, power change amount) of FIG.
Hand over to.

The leakage amount calculation unit 25 uses the relational expressions f (ΔT, ΔW) and f (ΔT ', obtained from the database 27 and the database 34.
ΔW) is the relational expression ΔF = g (f (ΔT, Δ
W)), ΔF = g (f (ΔT, ΔW)) to obtain the leakage amounts ΔF, ΔF ′ per unit time. The leakage amount obtained from the temperature sensor 55 is ΔF, while the leakage amount obtained from the optical fiber 56 is ΔF. Therefore, the true leakage amount ΔFr exists between ΔF and ΔF ′.

Since the temperature sensor 55 and the optical fiber 56 have different temperature characteristics from the installation location, the relational expression is as shown in FIG. 7, and the relational expression of the temperature change amount, the power change amount and the leak amount for obtaining the leak amount is Prepare several minutes (2 sets) of temperature sensor.

In this embodiment, the amount of leakage per unit time was obtained by experiments such as the relationship between electric power and temperature, but the amount of leakage can also be obtained from the relationship between current and temperature.

According to the present invention, the temperature sensor amount, the leakage amount calculation unit 25, the database 27, and the database 34, which have relations with the temperature change amount, the power change amount, and the leakage amount per unit time obtained by the experiment, are stored in the database. By providing the leak amount, it is possible to accurately calculate the leak amount. (Fifth Embodiment) FIG. 8 shows a primary system and a secondary system of a cooling system of a nuclear reactor. Pump 84, 86, 87, 88, 90 5
This is an example in which a leak detection device with collectors 93, 94, 95, 96, and 97 is installed as a leakage risk point. Each collector has an optical fiber network 98. Since the optical fiber itself serves as a temperature sensor and can continuously measure the temperature of a portion, it is possible to simultaneously monitor the temperature at multiple points. The leakage determination device 20 identifies the leakage location.

[0031]

According to the present invention, a collector, a temperature controller, a temperature sensor, and a leakage determination device are installed at a leakage risk location such as a flange connected to a pipe through which a fluid such as gas or liquid flows. By measuring the heater power or the heater current and the amount of change in temperature, it is possible to accurately detect the leakage from the leakage dangerous place.

In particular, installing a temperature sensor in the vicinity of the leakage risk location is effective for early detection of leakage during operation of plant equipment or the like. Furthermore, according to the experimental results,
The leak amount can be estimated by providing a database and a calculation unit that reflects the relationship between the power amount, the temperature, and the leak amount.

[Brief description of drawings]

FIG. 1 is a block diagram showing a system configuration of a leak detection device according to the present invention.

FIG. 2 is a block diagram showing a system configuration of a leakage determination device according to a second exemplary embodiment including a leakage amount calculation unit 25 according to the first exemplary embodiment.

FIG. 3 is a diagram showing an embodiment of a leakage amount calculation method in the second embodiment.

FIG. 4 is a block diagram showing a system configuration of a leak detection device according to a third exemplary embodiment.

FIG. 5 is a block diagram showing a system configuration of a leakage determination device according to a third exemplary embodiment.

FIG. 6 is a block diagram showing a system configuration of a leakage determination device including a leakage amount calculation unit 25 according to a fourth embodiment.

FIG. 7 is a diagram showing an embodiment of a leakage amount calculation method in the fourth embodiment.

FIG. 8 is a diagram showing an application example of the fourth embodiment.

FIG. 9 is a diagram showing an example of a system configuration of a conventional leak detection device.

[Explanation of symbols]

11 ... Fluid, 20 ... Leakage determination device, 21 ... Data collection unit, 22 ... Wattmeter memory unit, 23 ... Wattmeter operation unit, 24 ... Leakage determination unit, 25 ... Leakage amount integration unit, 27
... database, 28 ... threshold value, 29 ... watt meter comparison unit, 30 ... temperature memory unit, 31 ... temperature calculation unit, 32
... Temperature comparison unit, 33 ... Threshold value, 34 ... Database,
52 ... Wattmeter or ammeter, 53 ... Collector, 54
... computer, 55 ... thermocouple (or optical fiber, platinum resistance), 56 ... optical fiber, 57 ... temperature controller, 58
… Feedback signal, 59… Power supply, 61… Piping, 62
... flange, 81 ... reactor, 82 ... core, 83 ... intermediate heat exchanger, 84 ... pump, 85 ... primary pressurized water cooler, 86
... pump, 87 ... pump, 88 ... pump, 89 ... secondary pressurized water cooler, 90 ... pump, 91 ... pressure gauge, 92 ... pressure gauge, 93 ... collector, 94 ... collector, 95 ... collector , 96
... collector, 97 ... collector, 98 ... network.

Continued front page    (72) Inventor Katsuhiro Okusawa             Hitachi 2-3-1, Saiwaicho, Hitachi-shi, Ibaraki             Engineering Co., Ltd. (72) Inventor Hiroshi Furuuchi             Hitachi 2-3-1, Saiwaicho, Hitachi-shi, Ibaraki             Engineering Co., Ltd. (72) Inventor Tamotsu Asano             3-1-1 Sachimachi, Hitachi City, Ibaraki Prefecture Stock Association             Hitachi, Ltd. Nuclear Business Division F term (reference) 2G067 AA16 BB25 CC01 DD27 EE09                 2G075 CA05 CA13 DA03 DA04 DA05                       DA10 DA16 EA01 FA14 FB03                       FB08 FB09 FB10 FB16 FB17                       FC03 GA15

Claims (6)

[Claims] 1. A collector placed at a measurement target part, a temperature sensor attached to the collector, a temperature controller and a heater for keeping a constant temperature in the collector by a feedback signal of the temperature sensor. Wattmeter to measure the power of the wattmeter or ammeter to measure the current, the data collection unit that captures the wattmeter power value, the wattmeter memory unit that stores the power value, the wattmeter memory unit power value and the current power It is equipped with a wattmeter calculator that calculates a value, a wattmeter comparator that compares a predetermined threshold value and the calculation result of the wattmeter calculator, and a leak determination unit that determines a leak occurrence based on the comparison result of the wattmeter comparator. A leak determination device, which determines whether or not a leak has occurred by comparing a change amount ΔW of a watt meter or a change amount ΔI of an ammeter with a predetermined threshold value during a predetermined time t. A leak detection device characterized by the above. 2. A data collection unit that captures a value of a temperature sensor in the leak detection device according to claim 1, a temperature memory unit that stores the value of the temperature sensor, and a value of the temperature sensor memory unit before a predetermined time. A leak determination device comprising a temperature calculation unit for calculating the value of a current temperature sensor, a leakage amount calculation unit, and a database, and after leak detection, the sum of products of the result of the watt meter calculation unit and the result of the temperature calculation unit is calculated. A leak detection device characterized in that the leak amount is obtained by 3. A data collection unit that captures a value of a temperature sensor in the leak detection device according to claim 1, a temperature memory unit that stores the value of the temperature sensor, and a value of the temperature sensor memory unit before a predetermined time. A leakage determination device comprising a temperature calculation unit for calculating a value of a current temperature sensor and a temperature comparison unit for comparing a predetermined threshold value and a calculation result of the temperature calculation unit, the change of a watt meter during a predetermined time t. A leak detecting device characterized by comparing the amount ΔW or the amount of temperature change Δt with a predetermined threshold value, and determining whether or not a leak has occurred when either one exceeds a threshold value. 4. The leak detection device according to claim 3, wherein a database of the number of installed temperature sensors, a temperature memory unit that stores the values of the temperature sensors, a value of the temperature sensor memory unit before a predetermined time, and the current time. Each temperature sensor installed has a temperature calculation unit that calculates the value of the temperature sensor, and after the leak is detected, the result of the wattmeter calculation unit and the result of the temperature calculation unit are summed to calculate the sum of the leak amounts. A leak detection device characterized in that it is estimated to be within the range. 5. The leak detection apparatus according to claim 2, wherein the leak determination unit determines the time t at which the leak has occurred, and the leak amount ΔF per unit time obtained at the time t, the time t
A leak detection device characterized by obtaining the absolute amount F of the leak amount by multiplying by. 6. The leak detection apparatus according to claim 3, 4, or 5, wherein the collector is networked with an optical fiber to monitor multiple points at the same time and to identify the leak location. A leak detection device characterized by being easily performed.