JPH0125413B2 - - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to an improvement in a pipeline rupture detection device for detecting rupture of a fluid pipeline.

Technical Background of the Invention and Its Problems For example, in the water supply business, water is supplied to water users such as residents and factories by installing water pipes underground. In particular, piping facilities in urban areas are large in scale and handle a large amount of water. Therefore, managing the facility is also difficult. In particular, bursting accidents that damage pipes caused by subway construction, foundation work for building construction, road construction, etc. can cause great damage to nearby residences and traffic. Therefore, it is necessary to detect the occurrence of an accident as soon as possible and to minimize the damage.

Therefore, in the past, as a device for detecting pipe rupture as described above, a flow voltage proportional to the flow rate of the pipe is held as a set voltage with a constant magnification for a predetermined time, and this set voltage is compared with a new flow voltage to determine the set voltage. There are devices that output a rupture detection signal when the time exceeds the specified value for a predetermined period of time or more. However, since such a detection device uses the flow rate as a detection element, it has the disadvantage that it may malfunction due to a change in the flow rate due to a change in the piping route or the activation of a water pump.

Further, as another means of the detection device, there is one that uses pressure as a detection element. In other words, this detection means calculates the loss pressure of the piping line corresponding to the flow rate in advance, and compares this calculated pressure with the current pressure.
The calculated pressure must be corrected each time due to changes in the pipe line, which is extremely troublesome.

Furthermore, there are conventional devices that use pressure and flow rate as detection elements. This detection means compares the flow rate and pressure a predetermined time ago with the current flow rate and pressure, and outputs a rupture detection signal when the respective deviations simultaneously exceed fixed set values. (Tokuko Showa 47
−47716). Although this method is considerably improved in terms of accuracy compared to the above two methods, for example, in the case of a low setting value that takes into account a state where the flow rate in the pipe line is small,
There is still room for improvement, such as deterioration in accuracy.

Purpose of the Invention The present invention has been made in view of the above-mentioned circumstances, and is a pipe rupture detection device that uses flow rate and pressure as detection elements and can improve accuracy by determining the difference in deviation of both elements over a predetermined time. The purpose is to provide

Summary of the Invention The present invention provides a detection section that detects the flow rate and pressure of fluid flowing through a pipe line and converts both signals into electrical signals, samples the flow rate and pressure signals from this detection section at a predetermined period, and outputs the sampling output. is output after being delayed by one period by the first holding circuit, and the respective deviations between the flow rate and pressure signal delayed by one period and the current flow rate and pressure signal are calculated by the comparison circuit. Further, both deviation signals are sampled at the same sampling period as described above, and the sampling output is delayed by one period by the second holding circuit and output. Then, calculate the difference in deviation between this one-cycle delayed flow rate and pressure deviation signal and the current flow rate and pressure deviation signal, and use the difference between these deviations to adjust the preset values at the same time. The structure is designed to generate an alarm when the limit is exceeded. In addition, for the above-mentioned set values, more appropriate set values can be obtained by taking into account fluctuations in the flow rate or pressure of the fluid in the pipeline during normal times, which is determined by the supply status of the fluid supply side. The above object is achieved by providing a set value correction circuit in the device.

Embodiment of the invention An embodiment of the invention is shown in the block diagram of FIG. 1 and the block diagram of FIG.
This will be explained using the characteristic diagrams shown in FIGS.

First, in Fig. 1, 1 is a fluid storage tank (for example, a water distribution reservoir in water supply business),
A first pump 2 and a second pump 3 are arranged in parallel. A first valve 4 and a second valve 5 are provided on the output sides of these two pumps 2 and 3, respectively, and the flows of both merge at the output sides of these two valves 4 and 5 and are connected to a piping line 6. be done.
Next, a flow rate detector 7 is provided at a suitable location in the piping line 6 to detect the flow rate of the fluid and output an electric signal proportional to the flow rate of the fluid. A conversion and amplification section 8 that performs conversion and amplification is connected to this flow rate detector 7. A first flow rate sampling circuit 9 that samples the output of the amplification unit 8 at a predetermined period is connected to the conversion amplification unit 8, and the output of the sampling circuit 9 is connected to the first flow rate sampling circuit 9. A first flow rate holding circuit 10 that holds and outputs the flow rate until the sampling time.
is connected. Furthermore, this first flow rate holding circuit 1
0 is a flow rate comparison circuit 11 for calculating and comparing flow rates.
The negative end of is connected. Note that the output side of the conversion amplification section 8 is connected to the other positive side end of the flow rate comparison circuit 11. A second flow rate sampling circuit 12 is connected to the flow rate comparison circuit 11, which samples the output of the circuit 11 at the same period as the first flow rate sampling circuit 9. Furthermore, this flow rate sampling circuit 1
2 is a second flow rate holding circuit 13 that holds and outputs the output of the same circuit 12 until the next sampling time.
A flow rate comparison/discrimination circuit 15 is connected via. This comparison/discrimination circuit 15 determines the deviation between the output of the second flow rate holding circuit 13 and the output of the flow rate comparison circuit 11, and if this deviation exceeds the output value of the flow rate setting value correction circuit 14, it outputs a flow rate discrimination signal. Output. Further, the flow rate setting value correction circuit 14 includes a conversion amplification section 8.
A positive set value is calculated based on the signal output from the conversion amplification unit 8 during normal operation of the piping line 6, and the set value is input to the comparison/discrimination circuit 15. A first normally open contact 16 that is closed in response to a flow rate discrimination signal of the circuit 15 is connected to the comparison discrimination circuit 15 . Note that this first normally open contact 16 is connected to an alarm, etc. (not shown in the figure).
It is connected to the drive line 17 of. Flow rate detection is performed with the above configuration. Further, the set value correction circuit 14 performs settings that take into account the flow rate fluctuation state of the piping system during normal times, that is, the number of pumps and the state of the pipe line 6. When the normal flow rate is large, a large set value is set. If it is less, output a smaller setting value.

In addition, in the pressure detection means, a pressure transmitter 18 is provided in the piping line 6 for detecting the pressure of the fluid and outputting an electric signal proportional to the pressure. A first pressure sampling circuit 19 , a first pressure holding circuit 20 corresponding to the first flow rate holding circuit 10 , a pressure comparison circuit 21 corresponding to the flow rate comparison circuit 11 , a second pressure holding circuit 20 corresponding to the second flow rate sampling circuit 12 A pressure sampling circuit 22 and a second pressure holding circuit 23 corresponding to the second flow rate holding circuit 13 are provided. The output of the pressure comparison circuit 21 and the output of the second pressure holding circuit 23 are compared as a circuit corresponding to the flow rate comparison/discrimination circuit 15, and when the deviation exceeds a preset value, the pressure A pressure comparison and discrimination circuit 24 that outputs a discrimination signal is provided. Note that a flow rate set value correction circuit 14 for detecting flow rate is not provided. The pressure comparison and discrimination circuit 24 also includes the first normally open contact 16 for detecting the flow rate.
A second normally open contact 25 is connected which performs the same function as . However, the series connection of the first normally open contact 16 and the second normally open contact 25 is connected to the drive line 17 of the alarm or the like.

Next, the operation of the apparatus configured as above will be explained. Note that flow rate detection and pressure detection are performed at the same time and timing. Therefore, the first and second flow rate sampling circuits 9, 12 and the first,
The second pressure sampling circuits 19 and 22 all operate at the same timing and with the same sampling period.

First, we will discuss flow rate detection. A fluid flow rate signal detected by the flow rate detector 7 from the piping line 6 at a certain time is sampled at a predetermined period by the first flow rate sampling circuit 9 via the conversion amplification section 8. This sampled flow signal Q _o-1
is held in the first flow rate holding circuit 10 for one cycle of the sampling circuit 9, and the flow rate comparison circuit 1
It is input to the negative side end of 1. At the same time, the current flow rate signal _Qo from the conversion amplification section 8 is transmitted to the flow rate comparison circuit 1.
1, and the same circuit 11 outputs a deviation signal ΔQ _o-1 of the flow rate between one cycle before the sampling and the current time. This deviation signal ΔQ _o-1 is sampled by the second flow rate sampling circuit 12 and held by the second flow rate holding circuit 13 for one cycle of sampling.
It is input to the negative side end of 5. At the same time, flow rate comparison circuit 1
1 to the current flow rate deviation signal ΔQ _o is input to the positive side end of the flow rate comparison and discrimination circuit 15. Then, in the same circuit 15, a difference signal (ΔQ _o - ΔQ _o-1 ) between the current deviation signal ΔQ _o-1 and ΔQ _o is obtained, and the positive set value signal from the flow rate set value correction circuit 14 is obtained. A comparison is made. Here, if the difference signal (ΔQ _o −ΔQ _o-1 ) exceeds the positive set value, the flow rate comparison and discrimination circuit 15
A flow rate discrimination signal is output from the first normally open contact 16.
Close.

On the other hand, in the case of pressure detection, a pressure signal of the fluid in the piping line 6 is extracted by the pressure transmitter 18,
Below, the deviation ΔP _o between the output P _o-1 of the first pressure holding circuit 20 and the output P _o of the pressure transmitter 18 is determined by the pressure comparison circuit 2.
Find it by 1. Furthermore, the output ΔP _o-1 of the second pressure holding circuit 23 and the output ΔP _o of the pressure comparison circuit 21
The pressure comparison/discrimination circuit 24 determines the deviation.
Then, this deviation (ΔP _o −ΔP _o-1 ) is the circuit 24
When the pressure exceeds the negative set value, a pressure discrimination signal is output to the second normally open contact 25. This second normally open contact 25 is now closed.

When the first and second normally open contacts 16 and 25 are simultaneously closed due to the simultaneous detection of flow rate and pressure, the drive line 17 is connected and an alarm or the like is activated.

Next, each state of the piping line 6 will be explained based on the above basic operation.

First, when the piping line 6 is in a normal state, if the sampling period of the device is set short, the difference in flow rate deviation (ΔQ _o −ΔQ _o-1 ) and the difference in pressure deviation (ΔP _o −ΔP _o-1 ) can be obtained. do not exceed their respective set values, so the first and second normally open contacts 16, 25 maintain their open states.

Furthermore, when the flow rate of the piping line 6 increases rapidly due to the activation of the first and second pumps 2 and 3 or the operation of the first and second valves 4 and 5, the fluid in the piping line 6 will experience an increase in flow rate and pressure. Become. Therefore, the difference in flow rate deviation (ΔQ _o -ΔQ _o-1 ) exceeds the positive set value and the first normally open contact 16 is closed. However, since the pressure deviation difference (ΔP _o -ΔP _o-1 ) does not exceed the negative set value, the second normally open contact 25 is never closed and no alarm is generated. Furthermore, the first
When the second pumps 2, 3 are stopped or the first and second valves 4, 5 are operated to reduce the flow rate or pressure of the fluid in the piping 6, the first normally open contact 16 opens, contrary to the above. Since only the second normally open contact 25 remains closed, no alarm is generated.

Next, when a rupture accident occurs at a certain point in the piping 6, the flow rate of the fluid in the piping 6 increases and the pressure decreases. Therefore, the difference in flow rate deviation (ΔQ _o −
ΔQ _o-1 ) exceeds the positive set point and the difference in pressure deviation (ΔP _o −ΔP _o-1 ) exceeds the negative set value, thus closing the first and second normally open contacts.
Therefore, a warning will be issued.

Next, when another situation similar to the above occurs, that is, when a valve or the like is suddenly opened on the demand side, the flow rate of the fluid in the piping 6 increases and the pressure decreases in the same manner as above. However, unlike the above-mentioned rupture accident, there are relatively few changes in flow rate and pressure due to opening operations of valves, etc. Therefore, the flow rate deviation ΔQ _o and the pressure deviation ΔP _o are also small, that is, the difference in flow rate deviation (ΔQ _o −ΔQ _o-1 ) and the difference in pressure deviation (ΔP _o −ΔP _o-1 ) are further reduced. In other words, the difference in flow rate and pressure deviation (ΔQ _o −
For ΔQ _o-1 ) and (ΔP _o −ΔP _o-1 ), there is a clear difference between a rupture accident and the opening operation of a valve on the demand side. This is shown in FIGS. 2 and 3 regarding the flow rate characteristics. In addition, Fig. 2 is a flow characteristic diagram of a valve (butterfly valve), and Fig. 3 is a flow characteristic diagram of a rupture accident. In both figures, the vertical axis shows the flow rate Q, and the horizontal axis shows time t. -1 and n indicate the sampling time. Therefore, as is clear from both figures, {difference in flow rate deviation due to rupture accident (ΔQ _o −
ΔQ _o-1 )}>{Difference in flow rate deviation due to valve opening operation (ΔQ _o −ΔQ _o-1 )}≒0, and the difference between both characteristics can be clearly distinguished. In other words, there is almost no reaction when opening a valve or the like. Therefore, no warning can be issued.

Further, the flow rate set value correction circuit 14 includes a first and a second flow rate set value correction circuit 14.
This takes into consideration the fact that when the pumps 2 and 3 are installed in parallel, the flow rate fluctuation is larger when the flow rate is high than when the flow rate is low, so the flow rate setting value also needs to be changed. That is, when the normal flow rate is high, a large set value is output, and when it is low, a small set value is output. Therefore, the circuit 14 is a circuit that operates to make the above-mentioned operation more accurate.

As described above, in the above embodiment, an appropriate flow rate setting value can be set regardless of whether the piping line has a high flow rate specification or a low flow rate specification.

Further, the present invention provides the same functions and effects as the above embodiment even when the pumps are installed in series as in the modification shown in FIG. Here, a modification of FIG. 4 will be explained. Components having the same functions as those in the embodiment of FIG. 1 are given the same numbers and their explanations will be omitted.
Reference numeral 1 denotes a fluid storage tank. Third and fourth pumps 30 and 31 for sucking fluid are installed in series in this fluid storage tank 1, and are connected to a piping line 6 through a valve 32. A flow rate detector 7 is provided at an appropriate location on this piping line 6,
Hereinafter, as in FIG. 1, a conversion amplification section 8, a first flow rate sampling circuit 9, a first flow rate holding circuit 10, a flow rate comparison circuit 11, a second flow rate sampling circuit 1
2, a second flow rate holding circuit 13, and a negative side input terminal of a flow rate comparison/discrimination circuit 33 having a fixed flow rate set value is connected to the second flow rate holding circuit 13. Further, the output of the flow rate comparison circuit 11 is connected to the positive input terminal of the flow rate comparison/discrimination circuit 33 . Further, the both quantity setting value correction circuit 14 shown in FIG. 1 is not provided. Furthermore, a first normally open contact 16 similar to that shown in FIG. 1 is connected to the flow rate comparison and discrimination circuit 33, which responds to a flow rate discrimination signal from the comparison and discrimination circuit 33. The above is the configuration of flow rate detection.

On the other hand, for pressure detection, a pressure transmitter 18 for detecting a pressure signal from the piping line 6 is provided as in FIG. 1, and a first pressure sampling circuit 19 and a first pressure holding circuit as in FIG. circuit 20, pressure comparison circuit 21, second pressure sampling circuit 2
2, a second pressure holding circuit 23, and this second pressure holding circuit 23 includes the same circuit 23.
The negative input terminal of a pressure comparison/discrimination circuit 34 for determining the deviation between the output of the pressure comparison circuit 21 and the output of the pressure comparison circuit 21 is connected thereto. Note that the output side of the pressure comparison circuit 21 is connected to the positive end of the pressure comparison and discrimination circuit 34. Further, a pressure set value correction circuit 35 that determines a set value is connected to this pressure comparison and discrimination circuit 34.
A negative set value is calculated based on the normal pressure signal of the piping line 6 from the pressure transmitter 18, and the set value is input to the pressure comparison and discrimination circuit 34. A second normally open contact 25 similar to that shown in FIG. 1 is connected to the pressure comparison and discrimination circuit 34, which responds to a pressure discrimination signal outputted from the circuit.

In the above-mentioned device, its action is the same as the first one above.
Similar to the embodiment shown in the figure, an alarm is issued by simultaneous output of the flow rate discrimination signal and the pressure discrimination signal from the flow rate comparison and discrimination circuit 33 and the pressure comparison and discrimination circuit 34. However, the difference from FIG. 1 is that the flow rate setting value is fixed, and the pressure setting value is changed depending on the piping line 6 in normal conditions. In other words, when the third and fourth pumps 30 and 31 are installed in series as shown in Fig. 4, the pressure fluctuation will be larger at high pressure than at low pressure, so it is necessary to change the pressure setting value. With this in mind, when the normal pressure in the pipe line 6 is high, the set value is large, and when it is low, the set value is set small.

In the above modification, an appropriate pressure setting value can be set regardless of the low pressure specification or high pressure specification of the piping line.

Effects of the Invention As detailed above, according to the present invention, the deviation between the current flow rate and pressure value and the value a predetermined time ago is determined, and the difference between this deviation and the deviation before a predetermined time is determined, By comparing the difference in deviation with the set value, it is possible to more clearly distinguish between a pipeline rupture accident and a similar phenomenon during normal times. In addition, it is possible to automatically set appropriate setting values that match the specifications of the pipeline. Therefore, it is possible to provide a highly accurate conduit rupture detection device that is flexible with respect to the conduit conditions.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram showing an embodiment of the pipe rupture detection device according to the present invention, Fig. 2 is a flow characteristic diagram of a valve (butterfly valve), Fig. 3 is a flow characteristic diagram due to a rupture accident, and Fig. 4 is a diagram showing flow characteristics of a valve (butterfly valve). The figure is a configuration diagram showing a modification of the pipe line rupture detection device according to the present invention. 6... Pipe line, 9, 12... First and second flow rate sampling circuits, 10, 13... First and second flow rate holding circuits, 11... Flow rate comparison circuit, 14... Flow rate setting value correction circuit, 15, 33 ...Flow rate comparison and discrimination circuit, 19,
22...first and second pressure sampling circuits, 2
0, 23...First and second pressure holding circuits, 21...Pressure comparison circuit, 24, 34...Pressure comparison discrimination circuit, 3
5...Pressure set value correction circuit.

Claims (1)

[Claims] 1 A detection unit that outputs a signal corresponding to the flow rate and pressure of the fluid in the pipeline, and a flow rate detection unit that samples and detects the signals output from these detection units at predetermined intervals, and holds and outputs them at each predetermined cycle. A first sampling and holding circuit for pressure compares the flow rate and pressure signals outputted by these first sampling and holding circuits with the current flow rate and pressure signal outputted by the detection section, and determines the flow rate deviation. A comparison circuit for flow rate and pressure that outputs a signal and a pressure deviation signal, and a flow rate and pressure deviation signal that samples and detects the flow rate and pressure deviation signal output from these comparison circuits at a predetermined period, holds and outputs the same at each predetermined period. second sampling and holding circuits for pressure; flow rate and pressure deviation signals output by these second sampling and holding circuits; and respective set values of current flow rate and pressure outputted by said comparison circuit; and a set value correction circuit that corrects and changes the setting of at least one of the set value of the flow rate or the pressure based on the signal from the detection section, A pipeline rupture detection device that operates when a difference in flow rate and pressure deviation simultaneously exceeds a set value.