SYSTEM AND METHOD FOR ACOUSTIC LEAKAGE DETECTION BY USE OF AN ULTRASONIC FLOW METER

Abstract

A method for acoustic leakage detection in a fluid pipe network (1) uses at least one ultrasonic flow meter (13) installed at a pipe (15, 17). The pipe connects a consumer site (3) to the fluid pipe network. The method includes detecting at least one sound wave traveling along the pipe and/or along fluid within the pipe from a sound source to the at least one ultrasonic flow meter, determining the traveling direction of at least one of the at least one sound wave, interpreting a sound wave of the at least one sound wave as a leakage sound candidate if the determined traveling direction of said sound wave is towards the consumer site, and interpreting a sound wave of the at least one sound wave as a background noise if the determined traveling direction of said sound wave is away from the consumer site.

Claims

1. A method for acoustic leakage detection in a fluid pipe network with at least one ultrasonic flow meter installed at a pipe that connects a consumer site to the fluid pipe network, the method comprising: detecting at least one sound wave traveling along the pipe or along fluid within the pipe or along the pipe and along fluid within the pipe from a sound source to the at least one ultrasonic flow meter; determining a traveling direction of at least one of the at least one sound wave; interpreting the at least one of the at least one sound wave as a leakage sound candidate if the determined traveling direction of said at least one of the at least one sound wave is towards the consumer site; and interpreting the at least one of the at least one sound wave as a background noise if the determined traveling direction of said at least one of the at least one sound wave is away from the consumer site.

2. The method according to claim 1, wherein determining the traveling direction of said at least one of the at least one sound wave is based on a phase shift, on a time shift or on an amplitude difference or based on any combination of a phase shift, a time shift and an amplitude difference between a first signal generated by a first ultrasonic transducer of the at least one ultrasonic flow meter and a second signal generated by a second ultrasonic transducer of the at least one ultrasonic flow meter, wherein the first ultrasonic transducer and the second ultrasonic transducer have an axial distance to each other.

3. The method according to claim 1, further comprising: identifying the at least one sound wave as a superposition of a first sound wave traveling towards the consumer site and a second sound wave traveling away from the consumer site; and interpreting the first sound wave as a leakage sound candidate and the second sound wave as a background noise.

4. The method according to claim 1, further comprising identifying a dominant frequency band in said at least one of the at least one sound wave if said at least one of the at least one sound wave is interpreted as background noise, and subtracting the dominant frequency band from the at least one sound wave.

5. The method according to claim 1, further comprising setting or updating leakage information data comprising information about an amplitude of said at least one of the at least one sound wave and the traveling direction of said at least one of the at least one sound wave.

6. The method according to claim 5, further comprising measuring a fluid flow through the pipe, wherein setting or updating the leakage information data is regularly, continuously or sporadically performed based on a predetermined schedule or upon an external command, and only when a measured fluid flow is below a flow threshold or is zero.

7. The method according to claim 5, further comprising wirelessly transmitting, regularly or sporadically based on a predetermined schedule, or upon an external command, the leakage information data from the at least one ultrasonic flow meter to an automatic meter reading system.

8. The method according to claim 7, wherein the leakage information data is transmitted in a course of scheduled readings of fluid flow and/or consumption data.

9. The method according to claim 7, further comprising validating the leakage information data by comparison with leakage information data received within a predetermined time window by the automatic meter reading system from one or more other ultrasonic flow meters installed at other pipes connecting other consumer sites to the fluid pipe network.

10. The method according to claim 5, further comprising wirelessly transmitting a leakage detection command signal from an automatic meter reading system to the at least one ultrasonic flow meter, wherein setting or updating the leakage information data is performed upon reception of the leakage detection command signal.

11. The method according to claim 10, further comprising receiving by the automatic meter reading system leakage information data from one of the at least one ultrasonic flow meter, wherein the leakage detection command signal is transmitted to one or more ultrasonic flow meters in the vicinity of said ultrasonic flow meter for validating said information data.

12. The method according to claim 1, further comprising: monitoring a plurality of ultrasonic flow meters installed at different pipes connecting different consumer sites to the fluid pipe network; and receiving leakage information data at an automatic meter reading system from one or more of said plurality of ultrasonic flow meters.

13. An ultrasonic flow meter for measuring a fluid flow in a pipe connecting a consumer site to a fluid pipe network, the ultrasonic flow meter comprising: an ultrasonic transducer configured to measure ultrasound signals for determining a fluid flow rate and further configured to detect at least one sound wave traveling along the pipe or along fluid within the pipe or along the pipe and along fluid within the pipe from a sound source to the at least one ultrasonic flow meter in a no-fluid-flow situation; and a processing means in signal connection with the ultrasonic transducer, the processing means being configured to determine a traveling direction of at least one of the at least one sound wave and to use or provide information about the determined traveling direction for interpreting said sound wave as a leakage sound candidate if the determined traveling direction is towards the consumer site and as a background noise if the determined traveling direction is away from the consumer site.

14. The ultrasonic flow meter according to claim 13, further comprising at least another ultrasonic transduce to provide at least two ultrasonic transducers comprising a first ultrasonic transducer and a second ultrasonic transducer, wherein the first ultrasonic transducer (T1) and the second ultrasonic transducer are spaced apart an axial distance to each other, wherein the processing means is configured to determine the traveling direction of said sound wave based on a phase shift, on a time shift and/or on an amplitude difference between a first signal generated by the first ultrasonic transducer and a second signal generated by the second ultrasonic transducer.

15. The ultrasonic flow meter according to claim 13, wherein the traveling direction towards the consumer site is a nominal direction of fluid flow through the ultrasonic flow meter.

16. A system for acoustic leakage detection in a fluid pipe network, the system comprising: an ultrasonic flow meter for measuring a fluid flow in a pipe connecting a consumer site to a fluid pipe network, the ultrasonic flow meter comprising: an ultrasonic transducer configured to measure ultrasound signals for determining a fluid flow rate and further configured to detect at least one sound wave traveling along the pipe or along fluid within the pipe or along the pipe an along fluid within the pipe from a sound source to the at least one ultrasonic flow meter in a no-fluid-flow situation; a processing means in signal connection with the ultrasonic transducer, the processing means being configured to determine a traveling direction of at least one of the at least one sound wave and to use or provide information about the determined traveling direction for interpreting said sound wave as a leakage sound candidate if the determined traveling direction is towards the consumer site and as a background noise if the determined traveling direction is away from the consumer site; and a wireless signal transmitter configured to wirelessly transmit, regularly or sporadically based on a predetermined schedule, or upon an external command, leakage information data comprising information about an amplitude of said sound wave and the traveling direction of said sound wave; and an automatic meter reading system for wirelessly receiving fluid flow data or consumption data or fluid flow and consumption data from the ultrasonic flow meter.

17. The system according to claim 16, wherein the ultrasonic flow meter is configured to transmit the leakage information data in a course of scheduled readings of fluid flow data or consumption data or fluid flow and consumption data.

18. The system according to claim 16, wherein the automatic meter reading system is configured to validate the leakage information data received from the ultrasonic flow meter by leakage information data received within a predetermined time window from one or more other ultrasonic flow meters installed at other pipes connecting other consumer sites to the fluid pipe network.

19. The system according to claim 16, wherein the automatic meter reading system is configured to wirelessly transmit a leakage detection command signal to the ultrasonic flow meter, wherein the ultrasonic flow meter is configured to set or update the leakage information data upon reception of the leakage detection command signal.

20. The system according to claim 16, further comprising at least another ultrasonic flow meter, to provide a plurality of ultrasonic flow meters installed at different pipes connecting different consumer sites to the fluid pipe network, wherein the automatic meter reading system is configured to receive leakage information data from one or more of said plurality of ultrasonic flow meters.

21. The system according to claim 19, wherein the automatic meter reading system is configured to transmit the leakage detection command signal to another one or more of said plurality of ultrasonic flow meters in the vicinity of said ultrasonic flow meter for validating said leakage information data.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In the drawings:

[0043] FIG. 1 is a schematic view of a fluid pipe network with a system for acoustic leakage detection according to the present disclosure;

[0044] FIG. 2 is a schematic flow diagram of an embodiment of a method for acoustic leak detection according to the present disclosure; and

[0045] FIGS. 3a, 3b and 3c are schematic views showing three different options for determining the traveling direction of sound waves by an ultrasonic flow meter according to the present disclosure.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0046] Referring to the drawings, FIG. 1 shows a fluid pipe network 1 in form of a district heating network for supplying consumer sites 3 with heat from a district heating plant 5. The consumer sites 3 may be private households, industrial consumers, or any other type of consumer site that represents a billable entity for a utility provider managing the district heating plant 5. It should be noted that the fluid pipe network 1 as shown in FIG. 1 in form of a district heating network is just an example. The fluid pipe network 1 could alternatively be a service water distribution network for supplying the consumer sites 3 with water or a gas supply network for supplying the consumer sites 3 with gas.

[0047] In the district heating network 1 as shown in FIG. 1, the heat is typically transferred from the fluid pipe network 1 to the consumer site 3 by way of a heat exchanger 7 as part of a heating system 9 at the consumer site 3. The heating system 9 at the consumer site 3 usually comprises a circulation pump 11 for transporting heated fluid to radiators or underfloor heating.

[0048] At each consumer site 3, there is an ultrasonic flow meter 13 installed at a pipe 15, 17 connecting the consumer site 3 to the fluid pipe network 1. In the example shown in FIG. 1, the ultrasonic flow meter 13 is installed at a pipe 15 connecting to a feed line of the district heating network 1. Alternatively, the ultrasonic flow meter 13 may be installed at pipe 17 connecting the consumer site 3 to a return line of the district heating network 1.

[0049] The ultrasonic flow meters 13 are in this shown example heat meters that are configured to measure, store and report heat consumption data. Two temperature sensors 19 may be provided at the pipes 15, 17 connecting to the feed line and the return line, respectively, for the ultrasonic flow meter 13 to register a temperature differential. In combination with a measured fluid flow in any fluid flow situation the ultrasonic flow meter can provide heat consumption data.

[0050] The ultrasonic flow meters 13 comprise one or more ultrasonic transducer configured to measure ultrasound signals and a processing means (processor) in signal connection with the one or more ultrasonic transducer. The processor is configured to determine a traveling direction of at least one of the at least one sound wave traveling along the pipe and/or along fluid within the pipe from a sound source to the ultrasonic flow meter in a no-fluid-flow situation and to use or provide information about the determined traveling direction for interpreting said sound wave as a leakage sound candidate if the determined traveling direction is towards the consumer site and as a background noise if the determined traveling direction is away from the consumer site. The ultrasonic flow meters 13 further comprises a wireless signal transmitter configured to wirelessly transmit, regularly or sporadically based on a predetermined schedule, or upon an external command, the heat consumption data via a wireless communication network (not shown) to a head-end-system (HES) 21 of an automatic meter reading system managed by the utility provider. The head-end-system (HES) 21 is shown in FIG. 1 to be located within the district heating plant 5. However, it should be understood that the head-end-system (HES) 21 may be located anywhere, e.g. in form of a cloud-based system or a computer server anywhere else. The automatic meter reading system may comprise a dedicated wireless communication network or may make use of an existing wireless communication network, e.g. a cellular mobile phone network, for communication between the head-end-system (HES) 21 and the ultrasonic flow meters 13 installed at the different consumer sites 3.

[0051] FIG. 1 shows a situation of a leakage 23 in a feed line of the fluid pipe network 1. A utility provider is highly interested in detecting the leakage 23 as quickly as possible, locating the leakage 23 as accurately as possible, and to estimate the size of the leakage 23 as well as possible. For this, the ultrasonic flow meters 13 can be used as “microphones” to listen into the fluid pipe network 1 for acoustic leak detection. This is, because the leakage 23 makes a leakage noise that travels along the pipes of the fluid pipe network 1 and/or along the fluid within the pipes. Acoustic leakage detection is preferably performed in a no-fluid-flow situation, in which there is no fluid-flow in the pipe 15, 17 the ultrasonic flow meter 13 is installed at, or at least the fluid flow is below a flow threshold. Thereby, the acoustic leakage detection is not hampered by fluid flow noise.

[0052] However, other background noise usually makes leakage detection difficult. For instance, the circulator pump 11 or other vibrations at the consumer site 3 is often present. The amplitude of such background noise may be factors or even magnitudes higher than the leakage sound of the leakage 23. The idea of the present disclosure is now to determine the traveling direction of a sound wave detected by the ultrasonic flow meter and to use the traveling direction as a filter criterium to increase the signal-to-noise ratio, e.g. the average amplitude of the leakage sound divided by the average amplitude of background noise. The filtering is based on the insight that most of the expected sound sources for background noise are located at the consumer site 3 and thus the sound waves of the background noise usually travel away from the consumer site 3. The leakage noise, however, travels towards the consumer site 3, so that the determined traveling direction can be used to separate the leakage sound from most of the background noises. In other words, any sound wave traveling towards the consumer site 3 is interpreted as a leakage sound candidate and any sound wave traveling away from the consumer site 3 is interpreted as a background noise. The interpretation of the sound wave may be performed directly at the ultrasonic flow meter 13, but preferably at the head-end-system (HES) 21 that receives leakage information data wirelessly from the ultrasonic flow meters 13.

[0053] FIG. 2 shows a flow diagram of steps of an example of a method for acoustic leak detection according to the present disclosure. Acoustic leak detection may start at step 101. The start 101 may be triggered regularly or sporadically based on a predetermined schedule or a upon an external command, e.g. a leakage detection command signal received by a ultrasonic flow meter 13 from the head-end-system (HES) 21. The ultrasonic flow meter 13 may detect a no-fluid-flow-situation, in which the fluid flow is below a flow threshold or zero, and stops the flow rate measurement at step 103. At step 105, the ultrasonic flow meter 13 detects a sound wave signal traveling along the pipe 15, 17 and/or along fluid within the pipe 15, 17 from a sound source to the ultrasonic flow meter 13. In case a background noise baseline is already set, it is compensated for by subtracting the background noise baseline from the detected sound wave in step 107. In the following step 109, the traveling direction of the sound wave is determined. This could be the sound wave detected in step 105 or a residual sound wave after subtracting the background noise baseline in step 107. In step 111, the sound wave, of which the direction was determined in step 109, is interpreted differently depending on whether the traveling direction of said sound wave is towards the customer site 3 or away from the customer site 3. If the traveling direction determined in step 109 is away from the consumer site 3, the sound wave is interpreted as a background noise and a dominant frequency band is isolated from the background noise in step 113. The isolated dominant frequency band is compared with a typical known background noise source, e.g. a circulator pump 11 running at a known speed, for associating the dominant frequency band with one of such known typical background noise sources. If the dominant frequency band can be associated with a typical background noise source, the dominant frequency band may be set in step 117 as the background noise baseline to be used in step 107 for subtracting from the sound wave detected in step 105. If the dominant frequency band cannot be associated with a typical background noise source, leakage information data is determined in step 119. The leakage information data comprises information about the amplitude of the background noise and an information that the traveling direction of the background noise is away from the consumer site 3. So, the background noise and/or the dominant frequency band thereof may be analyzed for other purposes, e.g. leakage detection within the consumer site, or learning about new background noise sources and their dominant frequency band.

[0054] If the traveling direction of the sound wave determined in step 109 is found in step 111 to be towards the consumer site 3, the leakage information data determined in step 119 contains information about the amplitude of the leakage sound candidate and an information that the traveling direction of the leakage sound candidate is towards the consumer site 3. For example, the amplitude may be represented by an integer value on an arbitrary scale, i.e. 0 to 1.023 represented by 10 Bits. The information about the traveling direction may be a Boolean value represented by a single bit. In step 121, the leakage information data is reported wirelessly to the head-end-system (HES) 21. At the head-end-system (HES) 21, the leakage information data received from the ultrasonic flow meters 13 is processed in step 123. So, the head-end-system (HES) 21 uses the leakage information data for interpretation and deciding on whether triggering a leakage alarm or not. The information about the traveling direction in the leakage information data may be used as a filter criterium for triggering a leakage alarm or not. Further filter criteria may be applied, such as a minimum amplitude threshold and/or a time-wise and location-wise coincidence of matching leakage information data from several ultrasonic flow meters 13. The acoustic leak detection may end at step 125 until it is restarted in step 101.

[0055] FIGS. 3a, 3b and 3c show different options for determining the traveling direction of a sound wave traveling along the pipe 15, 17 the ultrasonic flow meters 13 is installed at and/or along fluid within said pipe 15, 17. In the shown examples, the ultrasonic flow meter 13 comprises a measuring tube 25 which extends along the pipe the ultrasonic flow meter 13 is installed at. In FIGS. 3a, 3b and 3c, the nominal flow direction of fluid through the measuring tube 25 is from left to right, i.e. the measuring tube 25 has an inlet 27 shown on the left-hand side and an outlet 29 shown on the right-hand side. The ultrasonic flow meter 13 comprises two ultrasonic transducers T1, T2. A first ultrasonic transducer T1 is located closer to the inlet 27 than a second ultrasonic transducer T2 being located closer to the outlet 29. Thereby, the ultrasonic transducers T1, T2 have an axial distance D to each other (the ultrasonic transducers are spaced apart a distance D with respect to an axial pipe/flow direction). In a fluid-flow situation, the ultrasonic transducers T1, T2 are used to transmit and receive ultrasonic signals for determining a fluid flow through the measuring tube 25. In a no-fluid-flow situation, however, the ultrasonic transducers T1, T2 are used to listen to sound waves traveling along the pipe 15, 17 and thus the measuring tube 25 and/or the fluid within the measuring tube 25.

[0056] FIG. 3a shows an example of a continuous sinusoidal sound wave 31 traveling along the measuring tube 25. Due to the axial distance D between the two ultrasonic transducers T1, T2, there is a phase shift in the signals produced by the two transducers T1, T2. The sign of the phase shift is indicative of the traveling direction of the sound wave 31. Therefore, the traveling direction of the sound wave 31 can be determined based on the phase shift of the signals generated by the two ultrasonic transducers T1, T2.

[0057] FIG. 3b shows the same ultrasonic transducers in a situation when a sound wave in form of sound pulse 33 travels along the measuring tube 25 in the nominal flow direction, shown in FIG. 3b from left to right. The first ultrasonic transducer T1 located closer to the inlet 27 detects the sound pulse 33 earlier than the second transducer T2 located closer to the outlet 29. Therefore, a time shift Δt between the signals generated by the ultrasonic transducers T1, T2 is indicative of the traveling direction of the sound pulse 33.

[0058] In FIG. 3c, the same ultrasonic flow meter 13 is shown in a situation of a sound wave 35 decaying in amplitude along its travel from the first transducer T1 to the second transducer T2. Therefore, an amplitude difference between the signals generated by the two ultrasonic transducers T1, T2 is indicative of the traveling direction of the sound wave 35.

[0059] Where, in the foregoing description, integers or elements are mentioned which have known, obvious or foreseeable equivalents, then such equivalents are herein incorporated as if individually set forth. Reference should be made to the claims for determining the true scope of the present disclosure, which should be construed so as to encompass any such equivalents. It will also be appreciated by the reader that integers or features of the disclosure that are described as optional, preferable, advantageous, convenient or the like are optional and do not limit the scope of the independent claims.

[0060] The above embodiments are to be understood as illustrative examples of the disclosure. It is to be understood that any feature described in relation to any one embodiment may be used alone, or in combination with other features described, and may also be used in combination with one or more features of any other of the embodiments, or any combination of any other of the embodiments. While at least one exemplary embodiment has been shown and described, it should be understood that other modifications, substitutions and alternatives are apparent to one of ordinary skill in the art and may be changed without departing from the scope of the subject matter described herein, and this application is intended to cover any adaptations or variations of the specific embodiments discussed herein.

[0061] In addition, “comprising” does not exclude other elements or steps, and “a” or “one” does not exclude a plural number. Furthermore, characteristics or steps which have been described with reference to one of the above exemplary embodiments may also be used in combination with other characteristics or steps of other exemplary embodiments described above. Method steps may be applied in any order or in parallel or may constitute a part or a more detailed version of another method step. It should be understood that there should be embodied within the scope of the patent warranted hereon all such modifications as reasonably and properly come within the scope of the contribution to the art. Such modifications, substitutions and alternatives can be made without departing from the spirit and scope of the disclosure, which should be determined from the appended claims and their legal equivalents.

[0062] While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.

LIST OF REFERENCE NUMERALS

[0063] 1 fluid pipe network [0064] 3 consumer site [0065] 5 district heating plant [0066] 7 heat exchanger [0067] 9 heating system [0068] 11 circulator pump [0069] 13 ultrasonic flow meter [0070] 15 pipe connecting to feed line [0071] 17 pipe connecting to return line [0072] 19 temperature sensors [0073] 21 head-end-system (HES) [0074] 23 leakage [0075] 25 measuring tube [0076] 27 inlet [0077] 29 outlet [0078] 31 sinusoidal sound wave [0079] 33 sound pulse [0080] 35 sound with decaying amplitude [0081] T1 first transducer [0082] T2 second transducer [0083] 101 start [0084] 103 stop flow rate measurement [0085] 105 detect sound wave [0086] 107 compensate for background noise baseline [0087] 109 determine traveling direction of sound wave [0088] 111 use traveling direction as filter criterium [0089] 113 isolate dominant frequency band in background noise [0090] 115 associate dominant frequency band with a typical background noise source [0091] 117 set background noise baseline [0092] 119 determine a leakage information data [0093] 121 reporting leakage information data [0094] 123 process leakage information data [0095] 125 end