Methods for locating leaks in water supply networks

Abstract

A method for locating a leak point (19) in a water supply network, the water supply network having a water source (11) and one or more electronic water usage meters (21, 22) located on the user side, and calculating the length of a pipe (17) between the usage meter (21) and the location of the leak point (19) based on a time-temperature curve and the amount of water flowing through at least one usage meter (21).

Description

Technical Field

[0001] The invention relates to a method for locating a leak in a water supply network and a usage meter designed to carry out the method. Background Art

[0002] The most common water loss in a water network is caused by leaks in the pipe network. A variety of techniques can be used to detect and locate leaks in a water network. One of these techniques is based on acoustics. When water leaves a pressurized pipe through a leak, noise is generated. This noise can be used to detect and locate leaks. There are a variety of methods, which have in common that they all use analog detection devices (i.e., microphones, hydrophones, accelerometers, piezoelectric devices, etc.) to capture the leakage noise. The detection device can use one or more analog filtering techniques. The captured noise data can be processed using digital analysis. The analysis techniques used on the noise data can be more or less complex, ranging from simple energy measurements such as peak or rms values ​​to more advanced methods such as frequency analysis or correlation between more detection devices. Which strategy is used depends on parameters such as current consumption, detector spacing, wireless network capabilities, and detector capabilities.

[0003] Patent document WO2017 / 005687A1 discloses a fluid usage meter configured to detect acoustic noise level data to help locate fluid leaks in a fluid supply pipeline network. Since fluid usage meters are installed in every house, they can all be used for acoustic leak detection. This acoustic leak detection works very well in practice, but it is difficult to determine the exact location of the leak. Additional technologies are required for this, such as tracer gas, correlators, or ground penetrating radar. Since the exact location of the leak (the so-called precise location) is unknown, a large area must usually be searched. This is time-consuming, expensive, and hinders traffic. Summary of the invention

[0004] One object of the present invention is to provide an improved method for locating leaks in a water supply network. Another object of the present invention is to provide an apparatus for carrying out the method.

[0005] The method for locating a leakage point in a water supply network according to the present invention uses a time-temperature curve at a fixed point in the network and the amount of water flowing through the fixed point to calculate the length of the pipeline between the fixed point and the leakage location. The water supply network includes at least one water source and one or more electronic water usage meters located on the user side. The time-temperature curve and the amount of water flowing through are determined in the water usage meter, and the length of the pipeline between the water usage meter and the leakage location (the location of the leakage point) is calculated.

[0006] The main idea of ​​the present invention is to use a temperature curve that varies over time and the amount of water flowing through the usage meter to calculate the length of the pipe between the usage meter and the leak location. The temperature curve can be used to determine a time period, which is the time required for the liquid to flow from the leak to the usage meter. The usage meter knows the amount of liquid that has flowed through the usage meter during this period. If the cross-sectional area of ​​the pipeline is known, the length of the pipe between the usage meter and the leak can be calculated. According to the present invention, the temperature curve of the medium is used to locate the leak. How to use the temperature curve will be explained in further detail below. The main idea of ​​the present invention is to use the temperature changes in the water network between the water source and one or more water usage meters on the user side, because the time temperature curve is different if there is a leak in the pipe network or if there is no leak in the network to the usage meter.

[0007] Modern usage meters include electronics for measuring, calculating, and transmitting data to a head-end system, server, etc. The distance calculation may be done in the usage meter, head-end system or server, or in any computer, smartphone, tablet, etc. connected to the usage meter, head-end system or server.

[0008] Since each water supply network has a large number of usage meters, the method according to the present invention can be implemented by software and does not require any expensive technical investment.

[0009] The location of the leak can be achieved by at least one meter. This is preferably done by multiple meters. The more meters used for location, the more accurate the location. Of course, it is recommended to initiate the location of the leak by different meters, non-parallel but timed apart.

[0010] Since locating a leak is done using at least one usage meter, it is advantageous to use this or these usage meters not only to locate the leak, but also to detect the presence of a leak. Before locating the leak, the acoustic leak detection of one or more usage meters can be activated. If multiple usage meters are used, the location of the leak can be roughly estimated by using the pipeline noise level detected by these usage meters and caused by the leak. For locating the leak, preferably those usage meters that are closest to the leak are used.

[0011] The time temperature curve can be determined by collecting the temperature of the water by a temperature sensor arranged in or connected to the usage meter. Of course, if the temperature of the water is collected by measuring the speed of sound in the fluid inside the usage meter and calculating the temperature based on the measured speed, it is not necessary to arrange a temperature sensor in the usage meter. A known method for determining the temperature of a usage meter is to use a usage meter working with a piezoelectric element for measuring the flow rate. However, these usage meters require temperature adjustment before measurement, and this temperature adjustment can also be used to determine the temperature of the liquid flowing through.

[0012] The method for locating a leak according to the invention is based on the effect of the temperature of the water in the pipe network adapting to the ambient temperature. This effect depends of course on whether the water is flowing through the pipe (as it occurs due to a leak) or whether the water is stationary (not flowing). Sometimes it is necessary to make the water in the pipe flow or stop it flowing in order to form a step in the time temperature curve, which is necessary to determine the time interval for calculating the distance to the leak. According to the invention, before determining the time temperature curve (curve that changes over time) of the water flowing through the usage meter, the flow in the pipeline is stopped for a period of time.

[0013] Preferably, not only the temperature of the fluid flowing through the usage meter is determined, but also the temperature of the environment surrounding the usage meter. If multiple usage meters are used to locate a leak, the temperature of the environment surrounding each usage meter should be acquired. If there is no flow, the environment temperature will approach the temperature of the fluid in the pipeline of the usage meter after a period of time. If the flow in the pipeline stops for a period of time, the period of time should at least correspond to the time required for the temperature of the water in the pipeline leading to the usage meter to adapt to the temperature of the environment surrounding the pipeline. This may be important to induce a temperature jump in the pipeline at the leak location, because this temperature jump must be detected for the subsequent calculation of the distance between the leak and the usage meter.

[0014] This temperature jump must be detected in the time temperature curve acquired by temperature measurement inside the usage meter. If this temperature jump is detected, the pipe distance between the leak and the usage meter can be calculated based on the pipe cross section and the amount of water that flows through the usage meter in the time interval between the start of flow and the detection of the temperature jump.

[0015] It may be advantageous to correct the calculation of the pipe length by a compensation factor related to one or more of the following:

[0016] - Length of pipe from the meter to the outside wall of the house;

[0017] -The deviation of the pipe route from a straight line between the main distribution line and the house.

[0018] Since acoustic leak detection is performed using electronic usage meters, such acoustic leak detection should be performed before the leak location, which means that the leak location using at least one usage meter should be triggered by acoustic leak detection of that usage meter or a nearby usage meter.

[0019] An electronic usage meter as disclosed in patent document WO2017 / 005687A1 can be easily configured to perform this method of locating a leak point. The method can be implemented without any additional hardware. Implementation by software may be sufficient. However, it may be advantageous to have additional hardware. The usage meter may include a temperature sensor for sensing the temperature of the usage meter or the ambient temperature of the usage meter. These temperature sensors are quite cheap and do not require much space or analysis electronics. On the other hand, as previously mentioned, in the absence of a temperature sensor, the temperature of the water flowing through the usage meter can be determined by a temperature calibration process that occurs inside the usage meter to adjust the measurement of the flow rate, as is done in an ultrasonic usage meter. There the speed of sound in water is measured to determine the temperature of the water.

[0020] To stop the flow, preferably a usage meter with an electrically controlled integrated shut-off valve is used. Alternatively, the electrically controlled shut-off valve can be arranged in the pipeline before or after the usage meter. The control of the valve can be performed wirelessly or wired.

[0021] Since most electronic water usage meters do not have an external power source, but rather have an internal battery that must last a long time, it is recommended that the meter be limited to performing this leak location three, five, or any other number of times to ensure that performing the leak location does not affect the normal life of the meter.

[0022] Advantageously, the method according to the invention can be arranged for the usage meter by additional programming of the control electronics inside the usage meter. There may be special subcircuits in the electronics to do this. The signal transmission of these usage meters is wirelessly transmitted to the front-end system by radio. Of course, this radio transmission can be adapted to receive the signal by a special receiver, a smartphone or any other suitable receiving device. Alternatively, the inductive transmission of data and the electrical energy for performing the method according to the invention can be achieved through the housing of the usage meter.

[0023] The method for locating a leak according to the invention is preferably performed during a time period when the water flow is small, as this is usually at night or in the early morning. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention is described in detail below with reference to the accompanying drawings, in which:

[0025] Figure 1 The water supply network is shown in a very simplified form.

[0026] Figure 2 shows the time temperature curve collected by the meter, and

[0027] Figure 3A simplified water supply network is shown, comprising a number of consumers and usage meters as well as leaks that must be located.

[0028] The reference numerals are listed as follows:

[0029] 1 Water supply network

[0030] 2 Main lines

[0031] 3 Secondary pipeline

[0032] 4 Leakage points

[0033] 5. Dosage Scale

[0034] 11 Waterworks

[0035] 12 Central Pumping Station

[0036] 13 Main water distribution line

[0037] 14 Regions

[0038] 15 Lake

[0039] 16 nodes

[0040] 17 Small pipes / residential pipes

[0041] 18 Houses

[0042] 19 Leakage Points

[0043] 20 Section of pipeline 17

[0044] 21 Dosage Table

[0045] 22 Dosage Table

[0046] 23 Houses

[0047] 24 Small pipes / residential pipes

[0048] 25 nodes

[0049] Di Distance between the leakage point 19 and the usage meter 21

[0050] L Length of the pipe 20 between the leak point 19 and the usage meter 21 DETAILED DESCRIPTION

[0051] exist Figure 1 In FIG. 1 , the principle of different temperatures in a water supply network 1 is shown in a very simplified schematic diagram. The main line 2 of the network 1 has water flowing at a low temperature of, for example, 12° C. Due to the large amount of liquid flowing through the main line 2, the temperature is almost constant.

[0052] From the main line 2, secondary lines 3 branch off. These secondary lines lead to users, for example houses. In particular if there is little or no consumption on the consumer side, for example at night, the water temperature in the secondary lines 3 is adapted to the ground ambient temperature. This temperature can be, for example, 14° C. The higher temperature in the secondary lines 3 is shown with a dashed line.

[0053] exist Figure 1 In the figure, there is a leak 4 in the secondary line 3 in the lower left part. When water flows through this leak 4, even if there is no consumption in this secondary line 3, there is a low temperature corresponding to the water temperature in the main line 2 up to the leak 4. There is no flow from the leak 4 to the consumption side. Therefore, in this part of the secondary line 3, the temperature of the water will correspond to the ambient temperature after a period of time, which is 14°C.

[0054] If the secondary line 3 with the leak 4 is opened on the user side, the water in the line 3 will flow through the usage meter 5 on the consumer side.

[0055] exist Figure 2 The time-temperature curve of water staying in or flowing through the meter 5 is shown in FIG. When the flow starts, the temperature in the meter 5 corresponds to the temperature T in the house. House Shortly after the start, at time t0, the temperature of the flowing water drops to temperature T h , which is the temperature of the water in the portion of the secondary pipeline 3 between the leak point 4 and the usage meter 5.

[0056] At time t leak The temperature drops again to T F , which corresponds to the temperature of the main line 2 and the first part of the secondary line 3 up to the leak point 4. If the flow is now stopped, the temperature in the usage table 5 will rise again to the temperature T House .

[0057] In order to locate the leak point, determine t0 and t leak From the dosage table 5, it can be seen that in this time interval (t0-t leak ) how much volume of water has flowed through the usage meter 5 during the time interval t0-t1. In addition, the pipe size, that is, its diameter, can be pre-programmed into the usage meter or wirelessly transmitted to the usage meter. Typical diameters are between 50 mm and 100 mm. Since the pipe size of the secondary line 3 is known, the pipe length between the leak point 4 and the usage meter 5 can be calculated by using the time interval t0-t2. leak The volume of the internal flow is calculated by dividing the cross-sectional area of ​​the pipe. This is the basic principle of the method according to the invention.

[0058] exist Figure 3 How this method is implemented in practice is shown in:

[0059] The water for the water supply network shown comes from a waterworks 11 which has a large central pumping station 12 for pumping drinking water into distribution lines 13 which are the main lines of the water supply network. The temperature of the water from the waterworks 11 is typically between 5°C and 15°C. This temperature depends on the ambient temperature and the size of the water reservoir of the waterworks 11. In this example, it is assumed that the temperature of the water entering the distribution line 13 is 10°C. On its way through the distribution line 13, the water changes its temperature depending on the temperature of the surrounding soil and the flow rate. Figure 3 In the example, the distribution line 13 passes through an area 14 near a local lake 15 having a water temperature of 15° C. The temperature of the water in the lake 15 is transferred to the soil and through the soil to the water in the distribution line 13 passing through the area 14. In this example, the temperature of the water in the distribution line 13 passing through the area 14 is increased to 12° C., this temperature increase depending on, among other factors, the flow rate, the flow rate and the thermal conductivity of the pipe wall.

[0060] On the way through the distribution line 13, the water reaches a node 16, where the main distribution pipe 13 branches off a small pipe 17, which is a residential pipe leading to a house 18. The temperature of the water in this small pipe 17 is 12°C at the beginning. In the residential pipe 17, there is a leak 19 in the pipe. Water gushes through this leak 19. As far as the leak 19 is concerned, there is a continuous flow via the residential pipe 17 from the node 16 to the leak 19. If there is any drinking water consumption in the house 18, there is a smaller flow of water behind the leak 19 in the flow direction. If there is no drinking water consumption in the house 18, there may be no flow. As a result, the water temperature in the section 20 of the residential pipe 17 increases. The section 20 is that part of the pipe from the leak 19 to the house 18. In the section 20, the water temperature increases to 16°C, because the water inside the pipe is heated by the surrounding soil. This temperature in the section 20 of the pipe 17 depends of course also on the consumption of water in the house 18, and also on the temperature of the surrounding soil.

[0061] A usage meter 21 is provided in the house 18, which is an electronic usage meter that measures the flow rate by means of ultrasound technology. The usage meter 21 determines not only the volume flowing through the usage meter 21, but also the temperature of the water flowing through it. To measure the temperature, a temperature sensor may be provided inside the usage meter 21 to measure the temperature of the water flowing through the usage meter 21. Alternatively, when using a so-called absolute time measurement that can be implemented in the usage meter 21, the temperature of the water flowing through the usage meter 21 may be calculated in the water temperature determination unit by measuring the speed of sound in water.

[0062] The method for locating a leak 19 is most effectively performed when the flow of water to the house 18 is temporarily stopped to allow the water in the section 20 of the residential pipe 17 to adapt to the temperature of the surrounding environment. In addition, the water inside the usage meter 21 adapts to the ambient temperature in the house 18. When the flow through the usage meter 21 is started, the flow is at the water temperature T because the water in the usage meter 21 and the pipe leading to the usage meter 21 inside the house 18 adapt to the temperature of the house 18. House When the flow through the meter 21 starts and Figure 2 The positioning process begins at the beginning of the time-temperature curve shown.

[0063] When the usage meter 21 is in leak location mode, the temperature of the internal water is analyzed. When a sudden sharp drop is detected in the usage meter 21, it is reported to the front-end system via wireless communication. Figure 2 In this embodiment, the temperature T House (18℃) to temperature T H (16°C). When the water further reaches the usage meter 21 through the pipeline, at t o Start measuring the time and flow rate. The measured flow rate is, for example, one liter per second. Further observe the temperature of the water. When the temperature of the water flowing through the consumption meter 21 is at the second time t leak When descending, determine t0-t leak time interval, and further determine the time interval t0-t leak The volume of the internal flow is shown in Table 21. When the temperature is T H =16℃, the water in the pipe section 20 flows through the meter 21, and the temperature changes from T H =16℃ to T F = The second decrease of 12°C. At time t leak When the water from the portion of the residential pipe 17 between the node 16 and the leak point 19 reaches the usage meter 21, the temperature will drop again and the volume flowing through the usage meter 21 during this time interval will be reported to the head end system.

[0064] At time t0 and t leak After the two steep sides are detected, the position of the leak point 19 is calculated in the usage meter 21 or in the head-end system. Since the residential pipe 17 has a constant cross section, the time t0-t leak The volume of flow through the meter 21 divided by the cross-sectional area during the time interval The length of the section 20 is calculated by , where D is the diameter of the residential pipe 17. The result is a length L, which is the length L of the pipe 20 between the leak point 19 and the usage meter 21.

[0065] The time-temperature curve is usually not like Figure 2 The problem may be that the temperature difference in the residential pipe 17 before and after the leak point 19 is not large enough or does not drop sharply. This temperature difference should be as large as possible. Therefore, before starting the locating process, it is necessary to stop the flow of water through the section 20 of the pipe 17 by installing a stop valve inside or next to the usage meter 21. The stop valve is controlled by the control electronics of the usage meter and can be started to close after the first acoustic leak detection when the leak locating process is started. For this leak locating process, the valve remains closed for two or three hours, which should be the same time as the temperature of the water in the section 20 of the pipe adapts to the surrounding environment. If the flow must be interrupted for several hours, it is recommended to start the leak locating process at night.

[0066] After this time, the valve is opened and the aforementioned leak location process is started, so that a sudden temperature drop can be detected (see Figure 2 ).

[0067] Such acoustic leak detection is well known and there are usage meters configured to perform such acoustic leak detection. Both acoustic leak detection and leak location should be initiated by external control, because these methods performed by the usage meter require additional power, which must be provided by the limited battery inside the usage meter. For such acoustic leak detection, a plurality of usage meters 21 should usually be used.

[0068] Reference Figure 3 , there is a utility meter 21 in house 18, and another utility meter 22 in house 23. House 23 with utility meter 22 is connected by a small pipe 24, which is a residential pipe 24 and branches from distribution line 13 at node 25. Figure 3 As shown, node 25 is located after node 16 (in the direction of flow through distribution line 13). Depending on the distance, the acoustic leak detection performed by either or both of the usage meters 21 and 22 will detect the leak 19. When analyzing the acoustic leak detection curves of the usage meters 21 and 22, it can be clearly identified that the leak 19 is in the residential pipe 17, rather than in the residential pipe 24, which can be identified from the intensity of the acoustic leak signal. When the acoustic leak detection is completed, as previously described with reference to Figure 2 As described above, the leak location is performed by selecting the meter 21 by analyzing the time-temperature curve.

Claims

1. A method for locating a leak (19) in a drinking water supply network, the drinking water supply network comprising at least one water source (11) and one or more electronic water usage meters (21, 22) located on the user side, characterized in that: The length of the pipeline (20) between the usage meter (21) and the leakage point (19) is calculated based on the known cross section of the pipeline (20), the time-temperature curve of water flowing through one of the usage meters (21, 22) (21) and the amount of water flowing through the usage meter (21).

2. The method according to claim 1, characterized in that Acoustic leak detection is performed using at least one of the usage meters (21, 22) before calculating the length (L) of the pipeline (20) between the usage meter (21) and the location of the leak point (19).

3. The method according to claim 1 or 2, characterized in that: The temperature of the water is collected by a temperature sensor arranged on or connected to the usage meter (21).

4. The method according to any one of the preceding claims, characterized in that The temperature of the water is acquired by measuring the speed of sound in the fluid inside the usage meter (21) and calculating the temperature based on the measured speed.

5. The method according to any one of the preceding claims, characterized in that Prior to determining the time temperature profile of the water flowing through the usage meter (21), the flow in the conduit (20) is stopped for a period of time.

6. The method according to any one of the preceding claims, characterized in that The ambient temperature of the usage meter (21) is collected.

7. The method according to any one of the preceding claims, characterized in that Prior to determining the time-temperature curve of the water flowing through the usage meter (21), the flow in the pipe (20) is stopped for a period of time, wherein the period of stoppage corresponds at least to the time required for the temperature of the water in the pipe (20) leading to the usage meter (21) to adapt to the ambient temperature of the pipe (20).

8. The method according to any one of the preceding claims, characterized in that detecting temperature jumps in the time-temperature curve, wherein the time t0 at which a first temperature jump is detected and the time t1 at which a second temperature jump is detected after the flow through the usage meter (21) begins are determined. leak The time interval t0-t leak The amount of water flowing through the usage meter (21) during the period.

9. A method according to any one of the preceding claims, wherein: The calculated length of the pipeline (20) is corrected by a compensation factor, the compensation factor being related to one or more of the following: - the length of the pipe (20) from the consumption meter (21) to the outer wall of the house (18); - Deviation of the pipeline route from a straight line between the main water distribution line (13) and the premises (18).

10. The method according to any one of the preceding claims, characterized in that Leak locating is triggered by acoustic leak detection by at least one of the usage meters (21, 22).

11. An ultrasonic dosage meter (21, 22) having control electronics inside the dosage meter (21, 22), characterized in that: The control electronics is configured to perform the method according to any of claims 1-10.

12. The ultrasonic dosage meter (21, 22) according to claim 11, characterized in that: The usage meter (21, 22) comprises means for determining the temperature of the water flowing through the usage meter (21, 22) and / or the ambient temperature.

13. The ultrasonic dosage meter (21, 22) according to claim 11 or 12, characterized in that: There is a temperature sensor for sensing the temperature of the usage meter (21, 22) and / or the temperature of the environment surrounding the usage meter (21, 22).

14. The ultrasonic dosage meter (21, 22) according to any one of claims 11 to 13, characterized in that: The usage meters (21, 22) are configured to determine the temperature of the water flowing therethrough by measuring the speed of sound in water.

15. The ultrasonic dosage meter (21, 22) according to any one of claims 11 to 14, characterized in that: The usage meter (21, 22) comprises an electrically controlled integrated stop valve.

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