JPH0231125A - Leakage detector - Google Patents

Abstract

PURPOSE:To detect leakage at an early stage with high accuracy by providing a temp. detector, a max. value selection circuit and a comparing circuit. CONSTITUTION:The atmospheric temps. at the respective places in a machinery chamber 2 are detected as signals (c) to (f) and the highest temp. signal in the machinery chamber 2 is selected by a max. value selection circuit 6 to be compared with a set value 8 by a comparing circuit 7. If a high temp. fluid leaks from a machinery 1, said fluid is detected by temp. detectors 3c to 3f in the vicinity of a location of the leakage and the numerical values of the outputted signals 3c to 3f rise and, when each said values is larger than the preset value 8, the leakage of the high temp. fluid occurs and a signal is outputted from the circuit 7 and a leakage signal 10 is outputted through an OR circuit 18. The signals (c) to (f) are respectively inputted to individual differentiating circuits 14 to 17 and the rates of timewise change are operated to be compared with set values 23 to 26 by comparing circuits 19 to 22 and, when even one of the rates exceeds the set value, it is judged that a leakage occurs at the place where the detectors 3c to 3f are arranged and the leakage is confirmed by a delay circuit 28 for preventing erroneous operation and the leakage signal 10 is outputted from the circuit 18.

Description

[Detailed description of the invention] [Object of the invention] (Industrial application field) The present invention detects leakage of high-temperature fluid from equipment in a room where equipment and piping containing high-temperature fluid such as high-temperature steam are installed. The present invention relates to a leakage detection device.

(Prior art) In a room where equipment and piping containing high-temperature fluid such as high-temperature steam are normally installed, as shown in the equipment room plan view of FIG. In order to detect leakage of the high temperature fluid contained in the equipment 1, a plurality of temperature detectors 3a7'117 to 3f are arranged at various locations to measure the atmospheric temperature within the equipment room 2. Of these, the temperature sensor 3a is
The temperature of the cooling air supplied by the supply air conditioning duct 4 is measured near the discharge port 4a, and the temperature detector 3b measures the temperature of the cooling air in the equipment room 2 that has increased due to the heat load of the equipment 1 exhausted by the exhaust air conditioning duct 5. The air temperature is discharged from the air intake port 5a of the air conditioning duct 5.
Measurements are being taken nearby. Further, the temperature detectors 3C to 3f measure the local temperature within the entire device 2.

If high-temperature fluid leaks from equipment 1, the ambient temperature in equipment room 2 and the difference in supply and exhaust temperatures will rise due to the heat of the leaked high-temperature fluid, so this will be detected by humidity detectors 3a to 3f. It was determined that a leak had occurred.

FIG. 4 is a logic circuit diagram of this conventional detection device, where temperature signals a to f are temperature signals output from temperature detectors 3a to 3f, respectively, that is, temperature signal a is a temperature signal from temperature detector 3a. It shows.

The humidity signals C to f of the atmosphere inside the equipment room 2 are input to the maximum value selection circuit 6, and the highest temperature signal inside the equipment room 2 is selected. This signal is further compared with a predetermined set value 8 in a comparator circuit 7, and if a signal larger than this set value 8 is input, it is assumed that a leak of high temperature fluid has occurred, and a leak signal is sent via an OR circuit 9. Send @10. Further, based on this leakage signal 10, if necessary, isolation work such as separating the device 1 from a high temperature fluid pipe (not shown) is performed. Further, the subtraction circuit 11 calculates the difference between the temperature signal a near the discharge port 4a of the supply air conditioning duct 4 and the temperature signal Rb of the intake port 5a of the exhaust air conditioning duct 5. increases, but the temperature at the discharge port 4a remains almost unchanged because the cooling air from the supply air conditioning duct 4 is being measured.
As a result, the differential temperature increases. Therefore, the output of the subtraction circuit 11 is compared with the set value 13 in the comparator circuit 12, and even if this temperature difference exceeds the set value 13, it is determined that a leak has occurred, and the OR
A leakage signal 10 was output from the circuit 9.

(Problem to be Solved by the Invention) The setting value 8 set in the conventional leakage detection circuit takes into account the normal room temperature of the entire equipment room 2, and the setting value 13 takes into consideration fluctuations in cooling air temperature during normal operation of the air conditioner. The values have been set with a margin to ensure that leakage signals will not be emitted immediately in the event of an air conditioner malfunction. Therefore, in the event that a leak occurs, the ambient temperature may be set at 8 or 8 depending on the location and extent of the leak.
]3, and a significant time delay occurs in the output of the leakage signal @10, making early detection difficult.

The present invention has been made in view of the above, and its purpose is to use conventional temperature detectors to detect not only the indoor temperature but also the rate of change of each temperature signal to determine the location of the temperature detector. Our objective is to provide a highly accurate leak detection device that is not easily affected by location, air conditioning operation, etc., and that is also capable of early detection and is highly reliable.

[Structure of the Invention] (Means for Solving the Problems) Temperature detection means are arranged at various locations in the room where equipment containing high-temperature fluid is installed and near the air supply and exhaust ports of the indoor air conditioner, and means for selecting the maximum value of the temperature signal, means for comparing this output signal with a set value, means for calculating the rate of change of each temperature signal from various parts of the room, means for comparing this output signal with the set value, and Second OR with the signal of the comparison means
a circuit, a means for delaying this output signal, a means for calculating a difference between the temperature signal from near the supply air and exhaust ports of the indoor air conditioner, a means for calculating a rate of change of this output signal, and a means for calculating a change rate between this output signal and a set value. A first OR circuit is provided which generates a leakage signal from the comparison means, the delay means, and the output signal of the comparison means between the maximum value of the temperature signal from various parts of the room and a set value.

(Function) Detects leakage of high-temperature fluid contained in the equipment by comparing the temperature rise in various parts of the equipment room, the rate of change of each temperature, and the rate of change of the supply air and exhaust temperature difference of the equipment room air conditioner with the set value. .

(Example) An example of the present invention will be described with reference to the drawings. Note that the same components as those in the prior art described above are given the same reference numerals, and detailed explanations will be omitted.

FIG. 1 is a logic circuit diagram of the detection device, and as shown in the plan view of the equipment room in FIG. The temperature signals @c, d, e, and f are input to the maximum value selection circuit 6, which is maximum value selection means, and the differentiation circuits 14, 15, 16, and 17, which are change rate calculation means for each signal. The output of the maximum value selection circuit 6 is compared with a predetermined set value 8 in a comparison circuit 7 as a comparison means, and is inputted to a first OR circuit 18.

Roughly speaking, each output from the differentiating circuit 14, 15, 16, 17 is connected to a comparing circuit 19, 20, 21, .
22, it is compared with the setting values 23, 24, 25, 26 for each location and input to the second OR circuit 27, and its output is input to the first OR circuit 18 via the delay circuit 28 of the delay means. Ru. Also, the outlet 4 of the air supply air conditioning duct 4 in the equipment room 2
A temperature sensor 3a is placed near a, and a temperature sensor 3b is placed near the intake port 5a of the exhaust air conditioning duct 5 to detect the temperature of the air conditioning cooling air and the exhaust temperature, and these temperature signals a and b are It is input to the subtraction circuit 11 which is a difference calculation means, and the result of the difference calculation is outputted to the first OR circuit 18 via two differentiating circuits which are change rate calculation means and a comparison circuit 12 which is a comparison means. The first OR circuit 18 is configured to output a leakage signal 10.

Next, the effects of the above configuration will be described. First, equipment room 2
The ambient temperature at each location within the equipment room 2 is detected as temperature signals C to f, and as in the past, the maximum value selection circuit 6 selects the highest temperature signal within the equipment room 2, and the comparison circuit 7 roughly selects the set value 8.
compared to If high-temperature fluid leaks from the device 1, the temperature detectors 3C to 3f near the leak location detect this, and the numerical values of the output temperature signals C to f increase. If this value is larger than a predetermined set value 8, a signal is output from the comparison circuit 7 indicating that a leak of high temperature fluid has occurred, and a leak signal 10 is output via the OR circuit 18.

Further, the temperature signals C to f are transmitted through individual differentiating circuits 14 to 1, respectively.
7, the temporal rate of change is calculated here, and the output is compared with predetermined set values 23 to 26, respectively, in separate comparison circuits 19 to 22. If the temperature exceeds the set value, this is different from a change in the cooling air temperature of a normal air conditioner or a temperature change due to a malfunction of the air conditioner, and it is determined that a leak has occurred at the location where the temperature detectors 3G to 3F are installed. As a precaution, the delay circuit 28 for preventing malfunctions confirms that the leakage signal is not caused by noise or short-term transient temperature changes, and the first OR circuit 18 outputs the leakage signal 10.

Note that the set values 23 to 2 for the individual comparison circuits 19 to 22
6 is larger than the rate of change in the temperature curve 30 when the air conditioning is stopped, and is the rate of change in the temperature curve 31 when a leak occurs, as shown in the equipment indoor temperature characteristic diagram in FIG. 3, where the horizontal axis is time and the vertical axis is temperature. By choosing a smaller value, it is possible to prevent erroneous leakage signals from being sent during normal operation.

That is, the set value is determined as shown in equation (1) below.

△Tl/Δt ΔT/Δt ΔT2/Δt・・・・・・
...(1) Here, Δt: Unit change time, ΔT1: Temperature change per unit time when air conditioning is stopped, ΔT2: Temperature change per unit time when leakage occurs, ΔT/Δt: Temperature of each temperature detection type This is the setting value for the rate of change in the degree of the detector installation location.

Next, to monitor the rate of change in the temperature difference at the air conditioning inlet and outlet, the temperature signal a of the supply air and the exhaust air from the air conditioning duct and the temperature signal S of the exhaust air are input to the subtraction circuit 11 to perform a difference calculation, and then differentiated. A circuit 29 calculates the rate of change with respect to time. If a leak occurs, the leaked high-temperature fluid flows into the equipment room 2, and this heat causes the temperature inside the equipment room 2 to rise and the exhaust temperature signal to rise. The temperature signal a is
Since the temperature of the cooling air at the discharge port 4a is measured, there is almost no change, and as a result, the differential temperature increases.

Therefore, the rate of change of the output of the subtraction circuit 11 is determined by the differentiator 29, and compared with the set value 13 in the comparator circuit 12. If this rate of change exceeds the set value 13, a signal is output from the comparator circuit 12, and the A leakage signal 10 is output from the OR circuit 18 of 1.

Now, if the average indoor ambient temperature of the equipment before the leak occurs is Ta, the equilibrium temperature at the time of the leak is T[, and the average time constant of temperature change during temperature rise is τ, then the temperature rise curve due to the leak is as follows (2 ) is expressed by the formula.

T=TL+ (Ta−TL)e”・(2) Differentiating the above equation (2), dT/ dt=TL −TA/ r e−”ζ・
(3) It can be seen that equation (3) is a monotonically decreasing function and takes the largest value at t=Q.

That is, immediately after a leak occurs, the rate of change in temperature still reaches a large value, so monitoring the temperature or temperature difference makes it possible to detect the leak early.

Now - as an example, Ta = 25 ('C), TL = 9
0 ('C) and τ=10 (minutes) to compare the leakage detection time between the conventional method and the present invention.

First, in the conventional technology, the temperature at which the leakage detection signal is emitted is set to 80 (
'C), the time required to reach the main temperature using equation (2) is t=19 (minutes).

Next, according to the present invention, when the temperature change rate at the time of leakage occurrence is determined using equation (3), it is 6.5 ('C/min) immediately after the leakage occurrence. Note that the temperature change rate is set as below, for example 5.
(°C/min), it becomes possible to detect leaks immediately after they occur.

The leakage signal 10 can be used to easily issue a leakage warning to an operator or an isolation work signal to disconnect the device 1 from a high-temperature fluid pipe (not shown) by closing an isolation valve or the like, as in the conventional case.

[Effects of the Invention] As described above, according to the present invention, leakage of high-temperature fluid in a room in which a device containing high-temperature fluid is installed is detected by detecting a rise in room temperature, as well as detecting the rate of temperature change and the difference in temperature. By monitoring the rate of temperature change and being unaffected by the operational status of indoor air conditioning equipment, it is now possible to detect leaks early and with high precision, improving the reliability of the detection device and the safety and reliability of the plant in which it is used. effective.

[Brief explanation of the drawing]

Fig. 1 is a logic circuit diagram of a detection device showing an embodiment of the present invention, Fig. 2 is a plan view of the equipment room, Fig. 3 is a temperature characteristic diagram in the equipment room, and Fig. 4 is a logic circuit diagram of a conventional detection device. It is. 1...Equipment, 2...Equipment room, 3a, 3
b, 3C13d, 3e, 3f...Temperature detector, 4...Air supply air conditioning duct, 4a...Discharge port, 5...
・Exhaust air conditioning duct, 5a...Intake port, 6...Maximum @ selection circuit, 7.12.19.20.21.22...Comparison circuit, 8
．． 13.23.24.25.26...Set value, 10.
...isolation signal, 11...subtraction circuit, 14.15.16.17.29...differentiation circuit, aSb
, c, dle, f...temperature signal. Agent Patent Attorney Norio Ogo/j Figure 1 Figure 2

Claims (1)

[Claims] Temperature detection means placed in various parts of the room where equipment and piping containing high-temperature fluid such as high-temperature steam are installed, and near the air supply and exhaust ports of the indoor air conditioner, and temperature signals from the temperature detection means in various parts of the room. Maximum value selection means, means for comparing this output signal with a set value, means for calculating the rate of change of each temperature signal from the temperature detecting means at various locations in the room, and means for comparing the output signal of this calculating means with the set value. , a second OR circuit that emits a signal based on the output signal of this comparison means, a delay means for this output signal, and a temperature signal difference between the temperature detection means arranged near the air supply and exhaust ports of the indoor air conditioner. a calculation means, a change rate calculation means for the output signal from the difference calculation means, a comparison means for the output signal and a set value, and output signals from the comparison means, the delay means, and the temperature signals at various locations in the room; A first OR circuit is provided which generates a leakage signal based on the output signal of the comparing means with a set value, and the leakage of high-temperature fluid is detected based on the rise and rate of change in the indoor atmospheric temperature and the rate of change in the difference in supply and exhaust temperatures of the air conditioner. A leak detection device characterized by detecting a leak.