GB2635653A

GB2635653A - Apparatus, systems and methods for determining the level of media within structures

Info

Publication number: GB2635653A
Application number: GB2316217.5A
Authority: GB
Inventors: Swahn Isak; Lieske Uwe; Gorski Dmistri; Sperle Thomas
Original assignee: Nicoustic AS
Current assignee: Nicoustic AS
Priority date: 2023-10-23
Filing date: 2023-10-23
Publication date: 2025-05-28
Also published as: GB202316217D0; WO2025087953A1

Abstract

The invention provides a method and system for determining a level of at least one medium, e.g. phases 120, 130, 140, contained within a structure, e.g. pipe 150, using an acoustic probe system which measures the propagation of acoustic waves within a wall of the structure. The method comprises selecting at least one of the plurality of acoustic probes 101-111 as an actuating element for excitation of the acoustic waves and selecting at least one of the plurality of acoustic probes 101-111 as a sensing element. The selection of the at least one actuating element and at least one sensing element is performed such that the level of the at least one medium can be determined within a target time. Different quantities of the acoustic probes may be used to determine a level measurement, and when a reduced quantity of acoustic probes are used a faster level measurement is obtained. A subset of two or three acoustic probes closest to an estimated / measured level may be used.

Description

1 APPARATUS, SYSTEMS AND METHODS FOR DETERMINING THE LEVEL OF MEDIA 2 WITHIN STRUCTURES 4 The present invention relates to apparatus, systems and methods for determining the levels of media contained within structures. The invention has particular application to 6 industrial applications which transport, store or process fluids and mixed phase media, 7 including the hydrocarbon industry, for example in the monitoring of levels of media 8 contained within oil and gas separators.

Background to the invention

12 When transporting, storing or processing media within structures such as vessels, tanks or 13 pipes, it is sometimes necessary to determine the level of media contained within the 14 structures. This is a common requirement within industrial applications which utilise or generate fluids and mixed phase media, including but not limited to the hydrocarbon 16 industry, pulp and paper industry, agricultural and bio-industrial applications, and process 17 industries in general. Structures such as tanks, vessels and pipelines are regularly used 18 to transport, store or process multiphase mixtures of media including gases, liquid 19 hydrocarbons, aqueous fluids, and solids. A particular example from the hydrocarbon industry is within oil and gas separators, where different phases, including liquids such as 21 oil or water, as well as solids and gases, are separated from one another by gravity.

23 Within such applications, it is desirable and may be essential to be able to obtain 24 measurements of the levels of the different media using non-destructive and non-intrusive methods. Furthermore, it is desirable to be able to obtain these measurements fast and 26 accurately, and without the need for specially trained personnel.

28 Acoustic-based inspection techniques are one of the common methods used for the 29 inspection of media contained within structures such as vessels and pipes. Within this category, techniques which use Guided Elastic Waves (GEVV), or Guided Ultrasonic 31 Waves (GUVV), are known to be beneficial due to the ability of guided waves to propagate 32 over long distances in the walls of the structure. During propagation of the guided waves 33 within a vessel wall, different media in contact with the interior of the vessel will result in 34 different attenuation rates of the measured signals. The measurements of attenuation rate provide information on the nature of the media present. Through the generation and 1 detection of these signals at different points around a vessel, a detailed understanding of 2 the contained media can be obtained.

4 Guided Elastic Waves (GEVV) or Guided Ultrasonic Waves (GUVV) methods rely on the positioning of multiple ultrasonic transducers around a vessel, and may lack speed in the 6 measurements they obtain, due to the complex and time-consuming nature of acquiring 7 data from numerous transducers.

9 EP4105612 Al describes a system which uses Guided Elastic Waves for monitoring containers in which different phases or media are stored or transported together. This can 11 include, in particular, oil, gas, water and solid particles. Several probes are arranged 12 around the container, each probe having at least one elastic wave-emitting element and at 13 least one elastic wave-detecting element. Using this system, damage and cracks can be 14 detected, and the fill level can be determined within the container.

16 US 5,719,329 describes a system which can be used to determine the flow velocity and 17 film heights of select fluids flowing within a pipeline. This system uses a plurality of 18 ultrasonic transducers which are coupled to the pipeline at both an upstream location and 19 a downstream location. At both locations, the transducers are positioned along a cross-sectional portion of the pipeline. A transducer control system is coupled to the upstream 21 and downstream transducers and is operable to generate and detect ultrasonic signals at 22 the upstream and downstream locations.

24 US 2009/0139337 Al describes a method for non-destructive inspection of coated or uncoated pipelines using ultrasonic transducers positioned around the circumference of a 26 pipe. The method is used to detect defects, and in particular to determine the axial position 27 of defects within the pipeline. Frequency tuning is used to move the natural focal points of 28 the sensors to different positions within the pipe.

These known methods attempt to solve different issues associated with the non- 31 destructive inspection of pipelines and their contents. However, none of these methods are 32 able to provide measurements of the levels of different media within walled structures with 33 a combination of accuracy and speed that is important in many applications, for example 34 when using separators, in which the presence of particular media and dynamic changes to their particular levels within the vessel requires faster level measurements to be obtained.

2 Summary of the Invention

4 It is amongst the aims and objects of the invention to provide a method for determining the level of different media within structures, which is an alternative to the methods described 6 in the prior art, and which addresses one or more of the problems of known apparatus and 7 methods.

9 It is amongst the aims and objects of the invention to provide a method for determining the level of different media within structures, which obviates or mitigates one or more 11 drawbacks or disadvantages of known apparatus and methods.

13 It is amongst the aims and objects of the invention to provide a method for determining the 14 level of different media within structures, and for reducing a time within which measurements can be obtained.

17 Further objects and aims of the invention will become apparent from the following

18 description.

According to a first aspect of the invention, there is provided a method for determining a 21 level of at least one medium contained within a structure using an acoustic probe system 22 which measures the propagation of acoustic waves within a wall of the structure, the 23 acoustic probe system comprising a plurality of acoustic probes mounted to the structure, 24 wherein the method comprises: -selecting at least one of the plurality of acoustic probes as an actuating element for 26 excitation of the acoustic waves; and 27 selecting at least one of the plurality of acoustic probes as a sensing element for 28 reception of the acoustic waves; 29 -wherein the selection of the at least one actuating element and the at least one sensing element is performed such that the level of the at least one medium can be 31 determined within a target time.

33 The method may comprise transmitting the acoustic waves between only two of the 34 plurality of acoustic probes at one time, wherein one of the acoustic probes is selected as the actuating element and the other is selected as the sensing element. In another 1 embodiment, the method may comprise transmitting the acoustic waves between three or 2 more of the plurality of acoustic probes simultaneously.

4 The plurality of acoustic probes may be connected by a common bus system.

6 The method may comprise using a plurality of acoustic probe systems which measure the 7 propagation of acoustic waves within a wall of the structure, and at least one of the 8 acoustic probe systems may comprise a plurality of acoustic probes mounted to the 9 structure, and connected by a respective common bus system. Alternatively, or in addition, an acoustic probe system may comprise two or more common bus systems, each 11 bus system connecting a subset of the acoustic probes.

13 The target time may be selected according to the mode, process or operation in which the 14 structure is being used. For example, where the structure is used in a dynamic process that has rapidly changing levels of media, the system may be required to have a relatively 16 short time constant, and the target time may be selected to be relatively short. In this 17 case, the system is relatively responsive to change. On the other hand, if the system is 18 used in a more static or steadily changing process that has slow changes in the levels of 19 media, the system may be required to have a relatively long time constant, and the target time may be selected to be relatively long. In this case, the system is relatively slower in 21 its response to change.

23 The target time may be 1 minute or less. In another embodiment, the target time may be 24 10 seconds or less. In another embodiment, the target time may be 5 seconds or less. In a preferred embodiment, the target time may be 1 second or less.

27 The plurality of acoustic probes may be mounted to an external surface of the structure. In 28 a preferred embodiment, the plurality of acoustic probes may be mounted to an external 29 surface of the structure by a non-intrusive method, such that no physical modification or alteration of the external surface is required.

32 The structure may comprise a tank, a vessel, a pipe or a pipeline.

34 The acoustic waves may have a frequency within the ultrasound range.

1 The method may further comprise: 2 determining a first measurement of the level of the at least one medium using a 3 first quantity of the plurality of acoustic probes; and 4 -determining a second measurement of the level of the at least one medium using a second quantity of the plurality of acoustic probes; 6 -wherein the second quantity of acoustic probes enables the second measurement 7 to be determined in a faster time than the first measurement.

9 As such, the method may comprise operating the system in a first mode, with a first measurement within a first target time, and may comprise operating the system in a 11 second mode, with a second measurement within a second target time.

13 The second quantity of acoustic probes may be a reduced quantity of acoustic probes in 14 comparison to the first quantity of acoustic probes. In another embodiment, the second quantity of acoustic probes may be a substantially reduced quantity of acoustic probes in 16 comparison to the first quantity of acoustic probes.

18 The method may comprise determining further measurements of the level of the at least 19 one medium. Further measurements of the level may be determined using the first quantity of acoustic probes, the second quantity of acoustic probes, or a different quantity 21 (lesser or greater) than either the first or second quantities. Thus further measurements 22 may be determined in either a faster, slower or the same time as either the first 23 measurement or the second measurement.

The method may further comprise: 26 determining the measurement of the level of the at least one medium using a 27 subset of the plurality of acoustic probes; 28 -wherein the subset of the plurality of acoustic probes is selected based on their 29 proximity to an estimated or measured level of the at least one medium.

31 The subset of acoustic probes may be a group of acoustic probes closest to an estimated 32 or measured level of the at least one medium. The subset of acoustic probes may be a 33 group of three acoustic probes closest to an estimated or measured level of the at least 34 one medium. In another embodiment, the subset of acoustic probes may be a group of two 1 acoustic probes closest to an estimated or measured level of the at least one medium.

2 The subset may be any other quantity of acoustic probes.

4 The method may comprise determining a further measurement of the level of the at least one medium, using the same subset of acoustic probes, or by using an alternative subset 6 of acoustic probes. The alternative subset of acoustic probes may be selected according 7 to their proximity to an estimated or measured level of the at least one medium, which may 8 be a different level, or which may be a changed or updated level.

The method may further comprise selecting the subset of the plurality of acoustic probes 11 based on their proximity to one another.

13 The subset of the acoustic probes may be selected such that one of the acoustic probes is 14 selected as the actuating element and a quantity of acoustic probes closest to the actuating element are selected as the receiving element.

17 The subset of the acoustic probes may be selected such that one of the acoustic probes is 18 selected as the actuating element and the four closest acoustic probes to the actuating 19 element are selected as the receiving element.

21 In another embodiment, the subset of the acoustic probes may be selected such that one 22 of the acoustic probes is selected as the actuating element and a quantity of the acoustic 23 probes are selected as the receiving elements, wherein the quantity of the acoustic probes 24 selected as the receiving elements are selected based on their proximity to the actuating element in a substantially downward direction. In one embodiment, the quantity of the 26 acoustic probes selected as the receiving elements may be the two closest acoustic 27 probes to the actuating element in the substantially downwards direction.

29 The further subset of the acoustic probes may be selected based on their proximity to each other.

32 The method may further comprise: 33 -acquiring a first set of data points from the plurality of acoustic probes; 34 -processing the first set of data points; determining a level of the at least one medium from the first set of data points; 1 acquiring a second set of data points from the plurality of acoustic probes; 2 updating at least one data point of the first set of data points with a corresponding 3 data point from the second set of data points to provide an interim dataset; 4 processing the interim dataset; and determining an interim level of the at least one medium from the interim dataset.

7 The first set of data points may be acquired using a subset of the plurality of acoustic 8 probes, or may be acquired from all of the acoustic probes. Where the first set of data 9 points is acquired from a subset of the acoustic probes, the subset may be a substantial quantity, such as a majority, of the acoustic probes.

12 The second set of data points may correspond to the first set of data points, acquired in a 13 second data acquisition period. The method preferably comprises updating at least one 14 data point of the first set of data points with a corresponding data point from the second set of data points to provide an interim dataset during the second data acquisition period.

16 The method may comprise processing the interim dataset, and may also comprise 17 determining an interim level of the at least one medium from the interim dataset, during the 18 second data acquisition period. Therefore the method may comprise providing an interim 19 dataset, and optionally processing the dataset and determining an interim level, before the full second set of data points is acquired. The interim data set may be a first interim data 21 set.

23 The method may comprise acquiring a further set of data points from the plurality of 24 acoustic probes.

26 The method may comprise updating at least one data point of the first set of data points 27 with a corresponding data point from the further set of data points to provide a further 28 interim dataset. The method may comprise processing the further interim dataset; and 29 determining a further level of the at least one medium from the further interim dataset.

31 Thus, multiple interim datasets may be provided during the second data acquisition period, 32 and multiple interim levels may be determined during the time of acquiring a second full 33 data set. The method may be repeated to provide interim datasets at a higher frequency 34 than which full data sets can be acquired using a particular number of probes.

1 According to a second aspect of the invention, there is provided a system for determining 2 a level of at least one medium contained within a structure, the system comprising: 3 an acoustic probe system which measures the propagation of acoustic waves 4 within a wall of the structure, the acoustic probe system comprises a plurality of acoustic probes mounted to the structure; 6 wherein at least one of the plurality of acoustic probes is selected as an actuating 7 element for excitation of the acoustic waves; and 8 wherein at least one of the plurality of acoustic probes is selected as a sensing 9 element for reception of the acoustic waves; wherein the selection of the at least one actuating element and the at least one 11 sensing element is performed such that the level of the at least one medium can be 12 determined within a target time.

14 The plurality of acoustic probes may be mounted in a path around the structure, having a path dimension that extends vertically, wherein the plurality of acoustic probes are 16 mounted substantially vertically equidistant from one another.

18 The plurality of acoustic probes may be substantially equally spaced along the vertical 19 path dimension, but may be unequally spaced apart along the direction of the path itself (i.e. unequally spaced in 3 dimensional space). Thus, the path may follow the shape of 21 the structure but retain substantially equal vertical spacing in spite of the shape profile of 22 the structure.

24 The structure may have a substantially convex outer circumference. In such embodiments, the density of acoustic probes mounted in a portion of the path around the structure may 26 be at a minimum towards the vertically uppermost and lowermost portions of the path, and 27 may be at a maximum at the portion of the path that lies at the same vertical height as the 28 centre point of the structure.

Embodiments of the second aspect of the invention may include one or more features of 31 the first aspect of the invention or its embodiments, or vice versa.

33 According to a third aspect of the invention, there is provided a method for determining a 34 level of at least one medium contained within a structure using an acoustic probe system which measures the propagation of acoustic waves within a wall of the structure, the 1 acoustic probe system comprising a plurality of acoustic probes mounted to the structure, 2 wherein the method comprises: 3 determining a first measurement of the level of the at least one medium using a 4 first quantity of the plurality of acoustic probes; and determining a second measurement of the level of the at least one medium using a 6 second quantity of the plurality of acoustic probes; 7 wherein the second quantity of acoustic probes enables the second measurement 8 to be determined in a faster time than the first measurement.

The second quantity of acoustic probes may be a reduced quantity of acoustic probes in 11 comparison to the first quantity of acoustic probes. In another embodiment, the second 12 quantity of acoustic probes may be a substantially reduced quantity of acoustic probes in 13 comparison to the first quantity of acoustic probes.

The method may comprise determining further measurements of the level of the at least 16 one medium. Further measurements of the level may be determined using the first 17 quantity of acoustic probes, the second quantity of acoustic probes, or a different quantity 18 (lesser or greater) than either the first or second quantities. Thus further measurements 19 may be determined in either a faster, slower or the same time as either the first measurement or the second measurement.

22 Embodiments of the third aspect of the invention may include one or more features of the 23 first or second aspects of the invention or their embodiments, or vice versa.

According to a fourth aspect of the invention, there is provided a system for determining a 26 level of at least one medium contained within a structure, the system comprising: 27 an acoustic probe system which measures the propagation of acoustic waves 28 within a wall of the structure, the acoustic probe system comprising a plurality of 29 acoustic probes mounted to the structure; -a first measurement of the level of the at least one medium determined using a first 31 quantity of the plurality of acoustic probes; and 32 a second measurement of the level of the at least one medium determined using a 33 second quantity of the plurality of acoustic probes; 34 -wherein the second quantity of acoustic probes enables the second measurement to be determined in a faster time than the first measurement.

2 Embodiments of the fourth aspect of the invention may include one or more features of the 3 first to third aspects of the invention or their embodiments, or vice versa.

According to a fifth aspect of the invention, there is provided a method for determining a 6 level of at least one medium contained within a structure using an acoustic probe system 7 which measures the propagation of acoustic waves within a wall of the structure, the 8 acoustic probe system comprising a plurality of acoustic probes mounted to the structure, 9 wherein the method comprises: determining a measurement of the level of the at least one medium using a subset 11 of the plurality of acoustic probes; 12 wherein the subset of the plurality of acoustic probes is selected based on their 13 proximity to an estimated or measured level of the at least one medium.

The subset of acoustic probes may be a group of acoustic probes closest to an estimated 16 or measured level of the at least one medium. The subset of acoustic probes may be a 17 group of three acoustic probes closest to an estimated or measured level of the at least 18 one medium. In another embodiment, the subset of acoustic probes may be a group of two 19 acoustic probes closest to an estimated or measured level of the at least one medium.

The subset may be any other quantity of acoustic probes.

22 The method may comprise determining a further measurement of the level of the at least 23 one medium, using the same subset of acoustic probes, or by using an alternative subset 24 of acoustic probes. The alternative subset of acoustic probes may be selected according to their proximity to an estimated or measured level of the at least one medium, which may 26 be a different level, or which may be a changed or updated level.

28 Embodiments of the fifth aspect of the invention may include one or more features of the 29 first to fourth aspects of the invention or their embodiments, or vice versa.

31 According to a sixth aspect of the invention, there is provided a system for determining a 32 level of at least one medium contained within a structure, the system comprising 33 an acoustic probe system which measures the propagation of acoustic waves 34 within a wall of the structure, the acoustic probe system comprising a plurality of acoustic probes mounted to the structure; 1 a measurement of the level of the at least one medium determined using a subset 2 of the plurality of acoustic probes; 3 wherein the subset of the plurality of acoustic probes is selected based on their 4 proximity to an estimated or measured level of the at least one medium.

6 Embodiments of the sixth aspect of the invention may include one or more features of the 7 first to fifth aspects of the invention or their embodiments, or vice versa.

9 According to a seventh aspect of the invention, there is provided a method for determining a level of at least one medium contained within a structure using an acoustic probe system 11 which measures the propagation of acoustic waves within a wall of the structure, the 12 acoustic probe system comprising a plurality of acoustic probes mounted to the structure, 13 wherein the method comprises: 14 determining a measurement of the level of the at least one medium using a subset of the plurality of acoustic probes; 16 wherein the subset of the plurality of acoustic probes is selected based on their 17 proximity to one another.

19 The method may comprise selecting at least one of the plurality of acoustic probes as an actuating element for excitation of the acoustic waves and selecting at least one of the 21 plurality of acoustic probes as a sensing element for reception of the acoustic waves.

23 The subset of the acoustic probes may be selected such that one of the acoustic probes is 24 selected as the actuating element and a quantity of acoustic probes closest to the actuating element are selected as the receiving element.

27 The subset of the acoustic probes may be selected such that one of the acoustic probes is 28 selected as the actuating element and the four closest acoustic probes to the actuating 29 element are selected as the receiving element.

31 In another embodiment, the subset of the acoustic probes may be selected such that one 32 of the acoustic probes is selected as the actuating element and a quantity of the acoustic 33 probes are selected as the receiving elements, wherein the quantity of the acoustic probes 34 selected as the receiving elements are selected based on their proximity to the actuating element in a substantially downward direction. In one embodiment, the quantity of the 1 acoustic probes selected as the receiving elements may be the two closest acoustic 2 probes to the actuating element in the substantially downwards direction.

4 The method may comprise determining a further measurement of the level of the at least one medium using a further subset of the acoustic probes. The further subset of the 6 acoustic probes may be selected based on their proximity to each other, similarly to the 7 subset of the acoustic probes.

9 Embodiments of the seventh aspect of the invention may include one or more features of the first to sixth aspects of the invention or their embodiments, or vice versa.

12 According to an eighth aspect of the invention, there is provided a system for determining 13 a level of at least one medium contained within a structure, the system comprising: 14 an acoustic probe system which measures the propagation of acoustic waves within a wall of the structure, the acoustic probe system comprising a plurality of 16 acoustic probes mounted to the structure; 17 wherein a measurement of the level of the at least one medium is determined using 18 a subset of the plurality of acoustic probes; and 19 wherein the subset of the plurality of acoustic probes is selected based on their proximity to one another.

22 Embodiments of the eighth aspect of the invention may include one or more features of the 23 first to seventh aspects of the invention or their embodiments, or vice versa.

According to a ninth aspect of the invention, there is provided a system for determining a 26 level of at least one medium contained within a vessel, the system comprising: 27 an acoustic probe system configured to measure the propagation of acoustic 28 waves within a wall of the vessel, the acoustic probe system comprising a plurality 29 of acoustic probes mounted in a path around the vessel and having a path dimension that extends vertically; 31 wherein the plurality of acoustic probes are mounted substantially vertically 32 equidistant from one another.

34 The plurality of acoustic probes may be substantially equally spaced along the vertical path dimension, but may be unequally spaced apart along the direction of the path itself 1 (i.e. unequally spaced in 3 dimensional space). Thus, the path may follow the shape of 2 the vessel but retain substantially equal vertical spacing in spite of the shape profile of the 3 vessel.

The vessel may have a substantially convex outer circumference. In such embodiments, 6 the density of acoustic probes mounted in a portion of the path around the vessel, may be 7 at a minimum towards the vertically uppermost and lowermost portions of the path, and 8 may be at a maximum at the portion of the path that lies at the same vertical height as the 9 centre point of the vessel.

11 Embodiments of the ninth aspect of the invention may include one or more features of the 12 first to eighth aspects of the invention or their embodiments, or vice versa.

14 According to a tenth aspect of the invention, there is provided a method for determining a level of at least one medium contained within a structure using an acoustic probe system 16 which measures the propagation of acoustic waves within a wall of the structure, the 17 acoustic probe system comprising a plurality of acoustic probes mounted to the structure, 18 wherein the method comprises: 19 acquiring a first set of data points from the plurality of acoustic probes; -processing the first set of data points; 21 determining a level of the at least one medium from the first set of data points; 22 acquiring a second set of data points from the plurality of acoustic probes; 23 -updating at least one data point of the first set of data points with a corresponding 24 data point from the second set of data points to provide an interim dataset; -processing the interim dataset; and 26 determining an interim level of the at least one medium from the interim dataset.

28 The first set of data points may be acquired using a subset of the plurality of acoustic 29 probes, or may be acquired from all of the acoustic probes. Where the first set of data points is acquired from a subset of the acoustic probes, the subset may be a substantial 31 quantity, such as a majority, of the acoustic probes.

33 The second set of data points may correspond to the first set of data points, acquired in a 34 second data acquisition period. The method preferably comprises updating at least one data point of the first set of data points with a corresponding data point from the second 1 set of data points to provide an interim dataset during the second data acquisition period.

2 The method may comprise processing the interim dataset, and may also comprise 3 determining an interim level of the at least one medium from the interim dataset, during the 4 second data acquisition period. Therefore the method may comprise providing an interim dataset, and optionally processing the dataset and determining an interim level, before the 6 full second set of data points is acquired. The interim data set may be a first interim data 7 set.

9 The method may comprise acquiring a further set of data points from the plurality of acoustic probes.

12 The method may comprise: 13 -updating at least one data point of the first set of data points, with a 14 corresponding data point from the further set of data points to provide a further interim dataset.

17 The method may comprise: 18 -processing the further interim dataset; and 19 -determining a further level of the at least one medium from the further interim dataset.

22 Thus, multiple interim datasets may be provided during the second data acquisition period, 23 and multiple interim levels may be determined during the time of acquiring a second full 24 data set. The method may be repeated to provide interim datasets at a higher frequency than which full data sets can be acquired using a particular number of probes.

27 Embodiments of the tenth aspect of the invention may include one or more features of the 28 first to ninth aspects of the invention or their embodiments, or vice versa.

According to an eleventh aspect of the invention, there is provided a system for 31 determining a level of at least one medium contained within a structure, the system 32 comprising: 33 an acoustic probe system which measures the propagation of acoustic waves within a wall 34 of the structure, the acoustic probe system comprising a plurality of acoustic probes mounted to the structure, wherein the system is configured to: 1 acquire a first set of data points from the plurality of acoustic probes; 2 process the first set of data points; 3 determine a level of the at least one medium from the first set of data points; 4 acquire a second set of data points from the plurality of acoustic probes; update at least one data point of the first set of data points with a corresponding 6 data point from the second set of data points to provide an interim dataset; 7 process the interim dataset; and 8 determine an interim level of the at least one medium from the interim dataset.

Embodiments of the eleventh aspect of the invention may include one or more features of 11 the first to tenth aspects of the invention or their embodiments, or vice versa.

13 Brief description of the drawings

There will now be described, by way of example only, various embodiments of the 16 invention with reference to the drawings, of which: 18 Figure 1 is a schematic representation of a system for determining the level of media 19 contained within a vessel, according to an embodiment of the invention; 21 Figure 2A is a schematic representation of a method of determining the level of media 22 contained within a vessel, according to an embodiment of the invention; 24 Figure 2B is a graphical representation of the method of obtaining sequential measurements according to Figure 2A; 27 Figure 3 is a schematic representation of a further method of determining the level of 28 media, according to an embodiment of the invention; Figure 4A and 4B are graphical representations of methods for selecting a subset of 31 probes, according to an embodiment of the invention; 33 Figure 5A is schematic representation of a system and method for selecting a subset of 34 probes, according to an embodiment of the invention; 1 Figure 5B is a graphical representation of the method for selecting a subset of probes, 2 according to Figure 5A; 4 Figure 6 is a schematic representation of a system for determining the level of media contained within a vessel, according to an embodiment of the invention; 7 Figure 7 is a schematic representation of a further method for determining the level of 8 media contained within a vessel, according to an embodiment of the invention; Figure 8A to Figure 8C are graphical representations of a method of selecting a subset of 11 probes, according to an embodiment of the invention; 13 Figure 9 is a schematic representation of a further method for determining the level of 14 media contained within a vessel, according to an embodiment of the invention; and 16 Figure 10 is a schematic representation of a method according to an embodiment of the 17 invention, in which media level updates are provided at intervals which are shorter in 18 duration than a period required to acquire a full set of data points from a system of 19 acoustic probes.

21 Detailed description of preferred embodiments

23 Embodiments of the invention will be described in the context of the inspection of medium 24 contained within a structure with a circular cross-section, such as a vessel or pipeline. This is by way of example only, and it will be appreciated in at least some of its aspects, that 26 the invention is applicable to the inspection of structures with a variety of different cross- 27 sectional shapes.

29 The invention is described in the context of oil and gas operations, particularly for the monitoring of levels of media in the transport and storage of oil and gas, as well as the 31 monitoring of levels of media in oil and gas separators. It is appreciated that this invention 32 will be applicable across a number of different applications, including applications within 33 process manufacturing, the pulp and paper industry, and biofuel production.

1 Operation using full dataset 3 Referring firstly to Figure 1, there is shown generally at 100 a vessel 150 with a circular 4 cross-sectional shape. This vessel 150 is a pipeline used to transport and contain fluids for the oil and gas industry. In the example shown in Figure 1, the vessel 150 contains three 6 generic media 120, 130 and 140. The media may be different phases, such as liquids, 7 solids or gases, and may include, for example, sand, water or oil. These media may also 8 include foams and emulsions. Although three distinct media are shown here, it is 9 appreciated that this method is applicable where a different number of media are contained within the vessel. In addition, this method is applicable in circumstances where 11 there are not strict interface lines between adjacent media, for example in cases where 12 media are partially mixed or dispersed at an interface line.

14 Positioned around the circumference of the vessel 150, are eleven acoustic probes 101 to 111. When selecting the quantity of acoustic probes to install around the vessel it is 16 considered beneficial to have a greater quantity than what is required for the specific 17 application, such that there is a level of redundancy if there is a mechanical failure of one 18 or more of the acoustic probes. The acoustic probes are mounted equidistantly to one 19 another around the circumference of the vessel 150, and are mounted via a non-intrusive means, such as by clamping them around the surface of the vessel. Examples of methods 21 by which the probes can be mounted to the surface of the vessel are described in more 22 detail in EP4105612 Al. In the example shown, reference lines 160, which intersect the 23 centre of vessel 150 and the central axis of the acoustic probes, are all at equal angles to 24 one another. Between the three media 120, 130 and 140 are two interface lines 125 and 135. The media, and interface lines, are symmetrical about the central vertical axis of the 26 vessel. In such circumstances, the inventor has identified that acoustic probes are required 27 around only half of the circumference of the vessel.

29 Each of the acoustic probes 101 to 111 can be operated either as an actuating element for the excitation of acoustic waves, such as ultrasonic waves, or as a receiving element for 31 the reception of these waves. The acoustic probes function through the transmission and 32 detection of Guided Elastic Waves (GEVV), or Guided Ultrasonic Waves (GUW). Excited 33 waves will propagate through the vessel walls, and during this propagation they will 34 undergo different attenuation rates depending on the media present within the vessel. This attenuation, and the resulting change in the amplitude of the measured signals, will be 1 detected by the acoustic probe operating as the receiving element, and analysed further.

2 Alternatively, or in addition, the time of flight or frequency shifts in the acoustic waves can 3 be detected and analysed by the acoustic probes. The acoustic probes are all connected 4 to a common bus. By measuring and analysing the acoustic waves received by multiple acoustic probes, the level of the media can be determined. The measurement of the level 6 of a particular medium is the location at which the interface line between the particular 7 medium and the medium above it meets the vessel wall, on the side of the vessel where 8 the probes are situated.

Shown generally in Figure 2A is a flow diagram representing a method 200 for determining 11 the level of media contained within the vessel 150. Firstly, in step 210, sequential 12 measurements are obtained. To perform these sequential measurements, one of the 13 acoustic probes 101 to 111 is selected as the actuating element, or sender, for the 14 excitation of the acoustic waves. Of the remaining probes, a second probe is chosen as the receiving element, or receiver, for the reception of the acoustic wave. Following the 16 transmission of the acoustic waves between these two probes, a second set of probes is 17 then selected, and operated in the same manner. This second set of probes may include 18 either of the probes from the first measurement, and may include a further probe selected 19 from one of the remaining available probes. By sequentially using each probe as a receiver and sender, and transmitting acoustic waves between all possible combination of 21 the probes, a full dataset 220 is obtained.

23 Measurement matrix 280 in Figure 2B graphically illustrates all measurement combinations 24 which are obtained during the sequential measurements in step 210. Across the top of the matrix 280, columns 1 to 11 correspond to acoustic probes 101 to 111, respectively, when 26 configured as senders. Rows 1 to 11 of the matrix correspond to acoustic probes 101 to 27 111, respectively, when configured as receivers. Measurements which are obtained during 28 method step 210 are shown as shaded cells. Therefore, during method step 210, 110 29 individual measurement steps are performed. White cells in matrix 280 represent measurement combinations which are not obtained, such as when an acoustic probe is 31 operated as a sender and a receiver simultaneously.

33 Once the full dataset 220 is obtained, a pre-processing step is performed (not shown), for 34 example through filtering. An algorithm is then used in step 230, on the dataset 220, to calculate a measurement of the level of the media contained within the vessel. Examples 1 of methods which can be used for the pre-processing step, as well as examples of the 2 algorithms that can be used, can be found in Neubeck et al. (Sensors, 21(1), 179, 2021).

3 Once this level reading is obtained in step 240, in step 250 this sequence can then be 4 repeated to obtain updates of the level measurements of the media.

6 Selecting a subset of probes 8 Obtaining level measurements using method 200 can be very time consuming. Method 9 200 requires 110 individual measurement operations to be performed during step 210. The inventors found that the length of time required to complete step 210 limits the use of this 11 method in some applications.

13 Figure 3 shows a schematic representation of a method 300 which can be used for 14 reducing the length of time required to obtain a level reading. Firstly, in step 310, a target update rate is determined. This target update rate is the length of time in which the 16 operator requires a level reading to be obtained. The target update rate will depend on the 17 specific application of the method. As an example, when measuring the changing levels of 18 hydrocarbons in a separator, a long update rate is often sufficient as the levels tend to 19 change slowly over time. In contrast, when measuring rapid changes in fluid levels in oil and gas transport, it will be beneficial to have a shorter update rate.

22 In addition, within some applications, an operator may require an update rate which 23 changes with time, depending on factors such as the age of a well. As an example, when a 24 production from a well is first started, or after a period of shut-in, it may be initially beneficial to have a shorter update rate to monitor fluid levels during this initial more 26 dynamic time period. At a later time, when fluid levels become more static, it may be 27 appropriate to switch to having longer update rates.

29 In step 320, a specific number of acoustic probes are selected for the measurement operation. This specific number of acoustic probes are selected in such that by using this 31 subset of acoustic probes, the target update rate can be achieved. Different ways by which 32 a subset of the acoustic probes may be selected, will be described in more detail in the 33 following paragraphs. Sequential measurements using the subset of acoustic probes are 34 obtained in step 330, using the same procedure as described in step 210, except with this subset of probes. Steps 340, 350 and 360 correspond to steps 220, 230 and 240, 1 respectively, except that they are performed using the partial data set obtained from the 2 subset of probes. When a calculation of the level of the media is obtained in step 360, in 3 step 370 the method can then be repeated. When step 310 is repeated, either the same 4 update rate can be used or a new update rate can be selected by the operator.

6 By using a subset of probes, as described, the level reading update is obtained using a 7 partial dataset instead of a full dataset. Accordingly, the level reading update which is 8 obtained will be lower resolution as it is based on a smaller number of datapoints. The 9 compromise between accuracy, resolution and the time taken to obtain the measurements is a factor that the operator will need to consider, and this will depend on the specific 11 application in which this measurement is being used.

13 One way in which a subset of probes can be selected in step 320, is by performing 14 measurements with acoustic waves being transmitted between probes in a single direction only. This will be understood with reference to Figure 2B. When obtaining the level reading 16 using the full dataset, there are individual measurement steps where probe 102 sends 17 acoustic waves to probe 101, and also where probe 102 receives acoustic waves from 18 probe 101. The inventors observe that by only sending acoustic waves from probe 102 to 19 101, and not sending acoustic waves in the reverse direction, that this does not significantly impact the overall accuracy of the level reading that will be obtained. When 21 applying this concept of transmitting acoustic waves in a single direction only, to all of the 22 acoustic probes, the total number of measurement steps required is reduced by half.

24 Further methods for selecting a subset of the probes are illustrated graphically in measurement matrices 400 and 450, in Figure 4A and Figure 4B, respectively. Across the 26 top of matrices 400 and 450, columns 1 to 11 correspond to acoustic probes 101 to 111, 27 respectively, when configured as senders. Rows 1 to 11 of matrices 400 and 450 28 correspond to acoustic probes 101 to 111, respectively, when configured as receivers.

The inventors have observed that when using probes which are positioned at large 31 distances to one another, that there is a reduced quality in the information obtained in 32 comparison to probes which are positioned close to each other. As such, the inventors 33 have found that level reading updates can be obtained with the exclusion of some of these 34 probes positioned at larger distances from one another, and that in doing this, the accuracy or quality of the level reading update is not significantly impacted.

2 As an example, in measurement matrix 400, a subset of probes is selected using only the 3 four nearest neighbours to each acoustic probes. With reference to acoustic probe 103 in 4 this example, when obtaining measurements using this subset of probes, acoustic probe 103 would send and receive acoustic waves from acoustic probes 101, 102, 104 and 105 6 only.

8 As a further example, in measurement matrix 450, a subset of probes is selected using the 9 two nearest neighbours to each acoustic probe, but where these two nearest neighbours are the two nearest neighbours in the vertically downward direction from each probe. In 11 this mode of operation, each of acoustic probes 101 to 111 would be operated in a 12 sending mode and would send an acoustic wave to the two acoustic probes positioned 13 below them only. With reference to acoustic probe 103 in this example, acoustic probe 103 14 would send acoustic waves to acoustic probes 104 and 105 only.

16 Figure 5 shows a further method for the selection of a subset of the probes. The vessel 17 and acoustic probe arrangement shown generally at 500 is similar to the arrangement 18 shown generally at 100, with like features indicated by like reference numerals 19 incremented by 500. Measurement matrix 580 graphically illustrates the measurement combinations which are obtained using acoustic probes 501 to 511. The row and column 21 numbers 1 to 11 correspond to acoustic probes 501 to 511, respectively. If the 22 approximate level of media in the vessel is already known, or can be estimated, probes 23 identified as being close to this approximate level may be selected for use. As an example, 24 in Figure 5, the three closest acoustic probes to each of the interface lines 525 and 535 are selected. Measurement matrix 580 graphically demonstrates the operation of acoustic 26 probes 504 to 509, as senders and receives in this example.

28 The inventors recognise that any number of acoustic probes either side of the interface 29 lines 525 and 535 may be selected for use. Furthermore, and more generally, the inventors recognise that there are a number of other ways in which subsets of acoustic 31 probes may be selected, and that this will depend on the specific application of this 32 method, as well as the accuracy required in the final level measurement. As an example, it 33 may be appropriate simply to select every other acoustic probes positioned around the 34 circumference of the vessel, for operation, thereby reducing the total measurement number by half.

2 Changing the installation pattern 4 Instead of reducing the total measurement time through the use of a subset of the available probes, a further method is to instead reduce the total number of acoustic probes 6 mounted on the vessel.

8 In Figure 1, acoustic probes 101 to 111 were mounted equidistantly to one another around 9 the circumference of the vessel 150. Shown generally at 600, Figure 6 demonstrates an alternate method for the mounting of acoustic probes 601 to 608, to a vessel 650.

11 Reference lines 655 are lines drawn horizontally from where the central axis of each of 12 acoustic probes 601 to 608 intersects the vessel 650. In this example, the acoustic probes 13 are positioned around the circumference of the vessel 650 such that they are positioned at 14 equal distances from each other in the vertical direction. As such, reference lines 655 are all at equal distances from each other. By mounting the acoustic probes in this way, a 16 minimum distance between the probes, or a maximum probe density, is achieved for 17 acoustic probes 604 and 605. In contrast, a minimum distance between the probes, or a 18 minimum probe density, is achieved at the lower and upper points of the vessel, towards 19 acoustic probes 608 and 601, respectively.

21 Partial updates of level measurements 23 Figure 7 shows a method 700 in which once a level reading is obtained using a full data 24 set, as in method 200, the level reading can be updated using a partial dataset from a subset of acoustic probes, as in method 300.

27 Method steps 710 to 750 correspond to method steps 210 to 250, respectively, and 28 method steps 760 to 780 correspond to method steps 320 to 340, respectively. Using 29 method 700 an initial level reading is obtained using the full dataset and the full number of acoustic probes. Following this, the level reading can then be updated using a partial 31 dataset from a reduced number of selected probes. The operator can perform any number 32 of level reading updates and these can be with either a full dataset or partial dataset, as 33 required. When selecting a subset of probes, this can be done through any of the 34 aforementioned methods. In addition, a subset of probes may be selected in any further 1 combination that may be useful for the operator, including combinations which are not 2 specifically disclosed herein.

4 In the following paragraphs, a number of examples will be given, demonstrating scenarios in which method 700 can be used.

7 Figure 8A to Figure 8C, show a graphical representation of the partial update of a full data 8 set over time, where the partial update occurs though the selection of a single probe 9 combination at time. Measurement matrix 810 represents an initial level reading update, where this is obtained using a full data set from a combination of all of the probes. Matrix 11 820 represents the next step where the level reading is updated using the single probe 12 combination highlighted by the light grey cell, with probe 102 as a sender and probe 101 13 as a receiver. Here, method steps 770, 780, 790, 730 and 740 are performed such that a 14 level reading update is obtained using this single probe combination only. Following this, matrix 830 represents the next step where a level reading is updated using a second 16 single probe combination, with probe 103 as the sender and probe 101 as the receiver, as 17 shown by the additional highlighted cell. Further level reading updates can be obtained 18 with further single probe combinations in this way.

The benefit of the method shown at 800 is that once a more accurate level reading has 21 been obtained, using a full dataset, further quick level updates can be obtained using small 22 partial datasets. Similarly to this method, the level reading can be updated using two probe 23 combinations at a time, or any number of probe combinations as the operate may 24 determine as necessary for a specific application.

26 A further use of method 700, by way of example, is that after a level reading update is 27 obtained using a full dataset, using steps 710 to 740, the location of the level of the media 28 will be known with good accuracy. As such, further level updates can then be obtained 29 using only the probes close to the media level, as demonstrated in Figure 5. After performing a number of level reading updates using this subset of probes close to the 31 media interface lines 525 and 535, a level reading update using a full dataset through 32 method step 750, may then be obtained to obtain a more accurate level reading update.

33 By switching to using this full data set again, and the resulting increased accuracy in the 34 level update, the operator can determine that an appropriate subset of probes are still being used, and that the media interface lines have not changed significantly. Following 1 this, further level reading updates can be obtained using the probes determined as close 2 to the media interface lines 525 and 535. As a further extension to this method, if it is 3 already known how the media levels will roughly change with time, then this use of full 4 dataset and partial dataset to obtain level readings updates, may be alternated in accordance with these level changes, such that more accurate readings can be obtained 6 only when it is deemed necessary by the operator.

8 Figure 9 is a graphical representation of a method 900 which represents a further method 9 by which the level measurement may be updated. This method is similar to method 700, with like features indicated by like reference numerals incremented by 200. Method 900 11 includes the addition of two new method steps, steps 982 and 984. Once the partial 12 dataset is obtained in step 980, as previously described, in step 982 the old data from the 13 previously obtained full data set is replaced with all of the new data obtained in the new 14 partial dataset. As such, in step 984 a partially updated full dataset is obtained which is a combination of old data and newly obtained data. In step 930, the algorithm is then used to 16 obtain a level reading update based on this partially updated full dataset.

18 Once the level reading is obtained in step 940, using the partially updated full dataset, 19 further level reading updates can then be obtained using either a further partially updated full dataset, or by using a fully updated dataset through method step 950. As such, in step 21 982, the full dataset which is updated may either be a partially updated full dataset from 22 previous iterations of method steps 960 to 990, or alternatively it may be a fully updated 23 dataset obtained through method step 950.

The benefit of method 900 is that the operator can obtain fast level reading updates, as 26 measurements are obtained using only a subset of the probes. This subset may be for 27 example using just two probes, as described in Figure 8. However, the operator is able to 28 still obtain high resolution level updates as each level reading update is obtained using a 29 full dataset rather than a partial dataset.

31 In some circumstances, it may be that the operator decides that it is not necessary to 32 obtain a level reading update following each parkal update of the full dataset in step 984.

33 In such circumstances, steps 960 to 982 can be repeated directly after step 984 to obtain 34 further updates to the full dataset without obtaining level reading updates each time. In these circumstances, step 990 is performed but steps 930, 940 and 950 would not bet 1 performed. As such, using this method, the operator can obtain successive partial updates 2 to the full dataset, and depending on the requirements may or may not obtain level reading 3 updates following each partial update of the full dataset. This process may be repeated 4 until a full update of the full dataset has occurred.

6 In method 900, the selection of the subset of probes in step 960 may be according to any 7 of the previously mentioned methods. In addition, method 900 may also be combined with 8 any of the previously described methods 200, 300 or 700, in any order as the operator 9 may require.

11 Method 900 may also be combined with the installation pattern of acoustic probes as 12 previously described with reference to Figure 6. The inventors also recognise that it may 13 be beneficial to combine the installation pattern of Figure 6 with any of the other previously 14 described methods 200, 300 or 700, or with any of the previously described methods by which a subset of the probes can be selected.

17 Figure 10 is a schematic representation of a method according to an embodiment of the 18 invention, in which media level updates are provided at intervals which are shorter in 19 duration than a period required to acquire a full set of data points from a system of acoustic probes. The method, shown generally at 1000, uses an acoustic probe system 21 which measures the propagation of acoustic waves within a wall of the structure, like 22 previously described embodiments of the invention, and may be used in conjunction with 23 any of the previously described methods and systems. During a data acquisition phase, 24 represented by block 1001, measurement data is acquired from i acoustic probes in the system to provide data points P1-1 to Pi-i. As previously described, there are limits to how 26 quickly the data can be acquired, particularly where there is a single common bus or low 27 number of data buses common to a relatively large number of probes, and the data 28 acquisition time may limit the sensitivity of the system to dynamic changes. The data 29 points corresponding to the probe combinations are acquired over the acquisition period 1010, until a full set of data 1030 (sufficient to determine a media level within the structure) 31 has been acquired. The full data set 1030 is then subject to processing 1040 to determine 32 a level output 1050. The processing 1040 and level determination are relatively quick 33 compared to the data acquisition period 1010.

1 After the first acquisition period 1010 (preferably immediately after), a second acquisition 2 period 1020 begins, in which measurement data is acquired from the i acoustic probes in 3 the system to provide new data points P1-1 to Pi-i. However, in this method, one or more 4 data points corresponding to a particular probe combination are used to update the previously acquired full data set 1030, before a second full set of data is acquired. For 6 example, data points acquired early in the second acquisition period (e.g. P1-1 and/or P1- 7 2) replace the corresponding data points from the previous acquisition period 1010, to 8 generate an interim data set 1060. The interim data set, which consists of a full set of data 9 points partially updated with recently acquired data, is processed to provide an interim level output 1070. Importantly, this interim level output is generated much faster than a 11 new level output based on a fully updated set of data points could be provided, and may 12 provide useful information on how a dynamic system is changing.

14 One or more data points of the interim data set 1070 is then updated with newly acquired data points to generate another interim data set, which is then processed 1040 to provide 16 a new interim level output 1070. The process may be repeated many times to output 17 multiple interim levels, each based on a partially updated dataset, before a second full set 18 of data 1080 has been acquired and processed to provide a new level output 1090 that is 19 based fully on data acquired in the second acquisition period. The method may be repeated for third and further acquisition periods as may be required. Where the 21 processing capability is fast enough relative to the data acquisition, an interim level may 22 optionally be calculated for each newly acquired data point, but in many applications, an 23 interim level will be calculated based on an interim data set based on the previous data set 24 and a number of updated data points, to provide a required number of interim level outputs.

27 In the context of this embodiment, references to "full data set" do not necessarily require 28 that each probe combination in the system provides a data point; a full data set is a data 29 set sufficient to calculate a level of media in the system, but as discussed with reference to previous embodiments, these may be data points acquired from a selected subset of the 31 probe combinations. In addition, what represents a "full data set" may change during 32 different measurement phases and/or modes of operation, as the balance between 33 measurement resolution and measurement times changes according to operational 34 requirements.

1 Multi-channel systems 3 In the aforementioned description, the invention has been described in the context of a 4 single-channel system, where the sequential measurements in steps 210. 330, 710, 770, 910 and 970 are obtained with one probe operating as the actuating element or sender 6 and another probe operating as the receiving element or receiver, at one time. It is also 7 possible to use a multi-channel system, where measurements can be obtained using three 8 or more probes operating as senders or receivers, at one time, or where a probe can 9 simultaneously be operated as a receiver and sender. Furthermore, using a multi-channel system, data from multiple subsets of probes can be analysed in parallel at the same time.

11 As such, it is possible to perform method 200 in parallel with method 300. Other 12 combinations of performing methods 200, 300, 700 and 900 in parallel, are also possible.

14 The benefits of obtaining level reading updates through the use of a multi-channel system, is that the level reading updates obtaining by using different subsets of probes, or by using 16 a subset of probes in contrast to the use of the full number of probes, can be compared, 17 and this can give the operator useful insight into how to most appropriately take further 18 level updates. As an example, this may guide the operator in determining whether using a 19 subset of the available probes will result in a large reduction in the accuracy of the level reading update and whether or not these reductions in accuracy are worthwhile when 21 considering the time saving benefits of using the reduced subset of probes. Furthermore, 22 the time limiting factor in single-channel systems is the time taken to obtain sequential 23 measurements using the different combinations of probes. As an example, in method step 24 210, 110 individual measurement steps need to be performed. As such, performing some of these measurement steps in parallel enables level updates to be obtain within faster 26 time scales, and without a drop in accuracy of the reading that is obtained.

28 By way of example, a level reading updated can be obtained using one of the subset of 29 probes demonstrated in measurement matrix 400 and 450. Simultaneously, a level reading update can be obtained using a full data set, as in method 200. The level reading updates 31 obtained using the subset of probes can be compared with the level update from the full 32 dataset, and if it turns out that there is not a significant reduction in the accuracy of the 33 level update obtained from the subset of probes, then the operator may wish to obtain 34 further level reading updates using the subset of probes.

1 Similarly, the operator may obtain a level reading update using a subset of probes next to 2 the interface lines 525 and 535, as demonstrated in Figure 5, and this may be compared to 3 a level reading update obtained using a full dataset. If it turns out that using this subset of 4 probes does not result in a significant reduction in the level reading update obtained, then the operator may again decide to continue to use this subset of probes.

7 Any of the subset of probes described herein can be used in this manner and compared 8 with a level reading update obtained from a full dataset, to guide the operator in the most 9 appropriate probe combinations to use, considering the time and accuracy requirements for the specific application.

12 The invention provides a system and method for determining the levels of media contained 13 within structures. In an aspect of the invention, the method comprises using an acoustic 14 probe system which measures the propagation of acoustic waves within a wall of the structure to determine the level of at least one medium within a target time. In an aspect of 16 the invention, the system comprises an acoustic probe system, wherein a plurality of 17 acoustic probes are mounted in a path around the structure, having a path dimension that 18 extends vertically, and wherein the plurality of acoustic probes are mounted substantially 19 vertically equidistant from one another.

21 Various modifications to the above-described embodiments may be made within the scope 22 of the invention, and the invention extends to combinations of features other than those 23 expressly claimed herein.

Claims

1 Claims 3 1. A method for determining a level of at least one medium contained within a structure 4 using an acoustic probe system which measures the propagation of acoustic waves within a wall of the structure, the acoustic probe system comprising a plurality of 6 acoustic probes mounted to the structure, wherein the method comprises: 7 selecting at least one of the plurality of acoustic probes as an actuating element for 8 excitation of the acoustic waves; and 9 selecting at least one of the plurality of acoustic probes as a sensing element for reception of the acoustic waves; 11 wherein the selection of the at least one actuating element and the at least one 12 sensing element is performed such that the level of the at least one medium can be 13 determined within a target time.

2. The method according to claim 1, wherein a plurality of acoustic probes are 16 connected by a common bus system.18

3. The method according to any preceding claim, wherein the target time is 10 seconds 19 or less.21

4. The method according to claim 1 or claim 2, wherein the target time is 1 second or 22 less.24

5. The method according to any preceding claim, wherein the plurality of acoustic probes are mounted to an external surface of the structure by a non-intrusive 26 method.28

6. The method according to any preceding claim, wherein the method further 29 comprises: determining a first measurement of the level of the at least one medium using a first 31 quantity of the plurality of acoustic probes; and 32 determining a second measurement of the level of the at least one medium using a 33 second quantity of the plurality of acoustic probes; 34 wherein the second quantity of acoustic probes enables the second measurement to be determined in a faster time than the first measurement.2

7. The method according to claim 6, wherein the second quantity of acoustic probes is 3 a reduced quantity of acoustic probes in comparison to the first quantity of acoustic 4 probes.6

8. The method according to claim 6, wherein the second quantity of acoustic probes is 7 a substantially reduced quantity of acoustic probes in comparison to the first quantity 8 of acoustic probes.

9. The method according to any of claims 6 to 8, wherein the method comprises 11 determining further measurements of the level of the at least one medium using a 12 further quantity of the plurality of acoustic probes.14

10. The method according to any preceding claim, wherein the method further comprises: 16 determining the measurement of the level of the at least one medium using a subset 17 of the plurality of acoustic probes.19

11. The method according to claim 10, wherein the subset of the plurality of acoustic probes is selected based on their proximity to an estimated or measured level of the 21 at least one medium.23

12. The method according to claim 10 or claim 11, wherein the method further comprises 24 determining a further measurement of the level of the at least one medium using the same subset of acoustic probes, or by using an alternative subset of acoustic 26 probes.28

13. The method according to claim 12, wherein the alternate subset of the acoustic 29 probes is selected based on their proximity to an estimated or measured level of the at least one medium, which may be a different level, or which may be a changed or 31 updated level.1

14. The method according to any of claims 10 to 13, wherein the method comprises 2 selecting the subset of the plurality of acoustic probes based on their proximity to 3 one another.

15. The method according to claim 14, wherein the subset of the acoustic probes are 6 selected such that one of the acoustic probes is selected as the actuating element 7 and a quantity of acoustic probes closest to the actuating element are selected as 8 the receiving element.

16. The method according to claim 14 or claim 15, wherein a further subset of the 11 acoustic probes are selected based on their proximity to each other.13

17. The method according to any preceding claim, wherein the method further 14 comprises: acquiring a first set of data points from the plurality of acoustic probes; 16 processing the first set of data points; 17 determining a level of the at least one medium from the first set of data points; 18 acquiring a second set of data points from the plurality of acoustic probes; 19 updating at least one data point of the first set of data points with a corresponding data point from the second set of data points to provide an interim dataset; 21 processing the interim dataset; and 22 determining an interim level of the at least one medium from the interim dataset.24

18. The method according to claim 17, wherein the first set of data points is acquired using a subset of the plurality of acoustic probes, or is acquired from all of the 26 acoustic probes.28

19. The method according to claim 17 or claim 18, wherein the method comprises 29 acquiring a further set of data points from the plurality of acoustic probes.31

20. The method according to claim 19, wherein the method comprises: 32 updating at least one data point of the first set of data points, with a corresponding 33 data point from the further set of data points to provide a further interim dataset; 34 processing the further interim dataset; and 1 determining a further level of the at least one medium from the further interim 2 dataset.4

21. A system for determining a level of at least one medium contained within a structure, the system comprising: 6 an acoustic probe system which measures the propagation of acoustic waves within 7 a wall of the structure, the acoustic probe system comprises a plurality of acoustic 8 probes mounted to the structure; 9 wherein at least one of the plurality of acoustic probes is selected as an actuating element for excitation of the acoustic waves; and 11 wherein at least one of the plurality of acoustic probes is selected as a sensing 12 element for reception of the acoustic waves; 13 wherein the selection of the at least one actuating element and the at least one 14 sensing element is performed such that the level of the at least one medium can be determined within a target time.17

22. The system according to claim 21, wherein the plurality of acoustic probes are 18 mounted in a path around the structure, having a path dimension that extends 19 vertically, and wherein the plurality of acoustic probes are mounted substantially vertically equidistant from one another.22

23. The system according to claim 21 or claim 22, wherein the structure has a 23 substantially convex outer circumference and wherein the density of acoustic probes 24 mounted in a portion of the path around the structure is at a minimum towards the vertically uppermost and lowermost portions of the path, and is at a maximum at the 26 portion of the path that lies at the same vertical height as the centre point of the 27 structure.