SYSTEM FOR DETECTING AND LOCATING A MATERIAL LEAK, AND ASSOCIATED METHOD.

Abstract

The invention relates to an instrumentation kit and a system capable of implementing a method for detecting a material leak from an industrial device, comprising the steps of measuring a vibration of a peripheral element arranged to receive a portion of material falling from the industrial device; and, in response to this measurement, and by means of an electronic computing system, generating a calculated signal representative of the fall of the falling portion of material at a drop point located on the peripheral element. Figure to be published with the abstract: Fig. 1

Description

Title of the invention: LEAK DETECTION AND LOCATION SYSTEM OF MATERIAL, AND ASSOCIATED PROCESS. TECHNICAL FIELD OF THE INVENTION

[0001] The invention relates to the detection and localization of a leak of liquid, soft or solid material from an industrial device transporting, transforming or containing this material. TECHNOLOGICAL BACKGROUND

[0002] The manufacturing industry, for example in the fields of chemicals, pharmaceuticals, metallurgy, agriculture, food, semiconductors, household appliances, or petroleum refining operations, transforms, handles, and transports matter in various forms. This matter may be in solid form, such as grains, powders, or masses of food, chemical, mineral, or metallic products. This matter may also be in liquid form, such as water, chemical solutions, beverages, oil, petroleum, or molten metal.

[0003] In all cases, it may happen that material escapes from the circuit it is intended to follow. For example, solid material may fall from a conveyor belt or pipes transporting liquid material may leak, allowing the transported liquid to escape.

[0004] In small-scale installations, detecting and locating the source of the leak remains a simple and quick operation. However, this operation rapidly increases in complexity and duration with the size of the installation concerned.

[0005] However, a leak from an industrial installation can lead to a total or partial shutdown of a production line, depending on the quantity or hazard of the product involved, for example, in the case of environmental contamination when dealing with toxic chemicals. Therefore, there is a strong incentive to detect a leak as early as possible and, ideally, to locate it and assess its extent.

[0006] US patent 10,692,351 B2 describes the detection of a leak in a water heating system by means of a moisture detection device.

[0007] US patent 8,064,738 B2 describes the detection and localization of a leak in a pipe using an optical fiber arranged along the pipe and sensitive to moisture.

[0008] US patent 2016 / 097696 A1 describes a piezoelectric sensor in contact with a piping element (pipe, valve, fitting), which is used to detect a leakage via vibrations caused by a fluid passing through the pipe at the point of the leak.

[0009] The devices known to the applicant are essentially adapted to liquids and require direct contact between a sensor and the leaking product and / or the piping conveying it.

[0010] There is a strong need for a versatile leak detection method, that is, one that operates independently of the nature of the leaking product, does not require direct contact with the leaking product or the leaking device, and is capable of assessing the location and extent of the leak, and monitoring it. Description of the invention

[0011] The applicant's objective is to propose a process and the associated system to meet the needs listed in the preceding paragraph, generally applicable to leaks of solid, liquid or soft matter.

[0012] The principle on which the system and method according to the invention are based is that of the indirect detection of a leak based on the vibrations generated by the impact of a portion of material falling from an industrial device onto a peripheral element. This peripheral element preferably takes the form of a plate extending under the industrial device without being limited to it, so as to receive the portion of material falling from it. The peripheral element may also consist of all or part of another element that can play the role of the plate, such as, for example, a containment tray, an example chosen from the detailed embodiments below.The peripheral element is instrumented so that the user can measure the vibrations propagating across its surface and generated by the impact of a portion of material falling from the industrial device due to a leak, measurements enabling the occurrence of the leak to be detected, its magnitude to be quantified, and its location to be determined.

[0013] To achieve this goal, one aspect of the invention is a method for detecting a material leak from an industrial device, comprising the steps of:

[0014] - measuring a vibration of a peripheral element arranged to receive a portion of material falling from the industrial device; and,

[0015] - in response to this measure, and by means of an electronic computing system, generate a calculated signal, representative of the fall of the portion of material falling at a drop point located on the peripheral element.

[0016] The method according to the invention makes it possible to detect the impact of falling material from an industrial device, and therefore to detect the occurrence of a leak within this industrial device. Proximity or immediate contact of the sensor with The leaking element or the material that has fallen is not necessary, the impact is detected indirectly via the vibrations it generates at the level of the peripheral element.

[0017] Thus, this is a process that can be applied equally to leaks of solid, liquid, or soft matter, regardless of the chemical nature of that matter. The only limiting criterion regarding the scope of application of this system is that the falling matter must generate vibrations at the peripheral element that can be detected by the vibration sensor.

[0018] Furthermore, using the peripheral element, which owes its designation to the fact that it is peripheral to the monitored industrial device, to detect leaks allows for monitoring that is completely neutral with respect to this industrial device and independent of any action, modification, maintenance, or other event that may affect it. A monitoring system for the industrial device can also be installed without having to modify or shut it down, simply by instrumenting a pre-existing element such as a containment basin to detect leaks, or by installing such a basin or, more generally, a suitable peripheral element given the situation.

[0019] According to additional non-limiting features of the process according to the invention, considered individually or in any technically feasible combination:

[0020] - the vibration can be measured at at least two distinct points of the element peripheral, and, in response to these measurements, the electronic computing system can generate (540) and emit a position signal representative of a position of the drop point;

[0021] - the method may further include (i) a step of instrumenting the element peripheral with at least one first sensor when this peripheral element is already positioned directly above the industrial device, or (ii) a step of instrumenting the peripheral element with at least one first sensor, followed by a step of positioning the instrumented peripheral element directly above the industrial device;

[0022] - the calculated signal can be representative of at least one piece of information chosen from an occurrence of the fall of the portion of falling matter, a kinetic energy of the portion of falling matter, a cumulative quantity of matter having fallen from the industrial device during a given period of time, a distance between a location of the first sensor and the point of fall of the portion of falling matter on the peripheral element (110, 110'), a state, either solid, or liquid or soft, of the portion of falling matter;

[0023] - the calculated signal can be calculated on the basis of a vibration detection signal and a signal representative of a nature of the portion of matter, the calculated signal being at least representative of a fall height of the portion of matter;

[0024] - the step of detecting the vibration of the peripheral element can be put into work by means of a first vibration sensor comprising a single-crystal piezoelectric thin layer extending along an extension plane, less than 50 pm thick and with dimensions greater than 100 pm in its extension plane, this thin layer being rigidly attached to the peripheral element; and

[0025] - the peripheral element can be a retention tray.

[0026] In addition to the advantages already mentioned, the method according to the invention can also determine the location, in the horizontal plane defined by the peripheral element, of the point at which a portion of material falls from the leak, as well as the height of the fall. Each of these pieces of information greatly simplifies the search for the origin of the leak and saves valuable time in locating it.

[0027] The method can also be used to quantify the leak by evaluating the kinetic energy released by the material upon impact with the peripheral element, energy directly related to the amount of falling material and therefore to the extent of the leak. This characterization of the leak makes it possible to schedule emergency intervention in the event of a major leak or, conversely, to prioritize other actions in the event of a minor leak.

[0028] The invention extends to an instrumentation kit configured to equip a peripheral element intended to be installed above an industrial device so as to form a system for detecting a leak of material falling from the industrial device, the kit comprising:

[0029] - at least one vibration sensor intended to generate and emit a signal of a sensor in response to a vibration of the peripheral element resulting from an interaction between a portion of the falling material and the peripheral element; and

[0030] - an electronic computing system that can be functionally connected to first sensor and being designed to, in response to the first sensor signal, generate and emit a calculated signal representative of the fall of the portion of material at a drop point located on the peripheral element.

[0031] According to additional non-limiting features of the instrumentation kit according to the invention, considered individually or in any technically feasible combination:

[0032] - the first calculated signal can be representative of at least one chosen piece of information among an occurrence of the fall of the portion of falling matter, a kinetic energy of the portion of falling matter, a cumulative quantity of matter having fallen from the industrial device during a given period of time, a distance between a location of the first sensor and the point of fall of the portion of falling matter on the peripheral element, a state, either solid, or liquid or soft, of the portion of falling matter;

[0033] - the first calculated signal can be calculated on the basis of the first sensor signal and a signal representative of a nature of the portion of matter, the first calculated signal being able to be at least representative of a fall height of the portion of matter;

[0034] - the instrumentation kit may further include a plurality of sensors vibrations each designed to emit an associated sensor signal in response to the vibration of the peripheral element, and functionally connected to the electronic computing system, wherein the electronic system can further be configured to generate and emit a position signal representative of a position of the drop point, based on the sensor signals; and

[0035] - the at least one sensor may comprise a piezoelectric thin layer monocrystalline extending along an extension plane, less than 50 pm thick and with dimensions greater than 100 pm in its extension plane.

[0036] The invention extends to a leak detection system for an industrial device comprising a peripheral element intended to be installed directly above an industrial device and equipped with the instrumentation kit according to the invention.

[0037] According to additional non-limiting features of the system according to the invention, considered individually or in any technically feasible combination:

[0038] - the system may further include a configured suspension device in order to isolate the peripheral element from mechanical vibrations from its environment; and

[0039] - the peripheral element can be a retention tray. BRIEF DESCRIPTION OF THE FIGURES

[0040] Other features and advantages of the invention will become apparent from the detailed description of the invention which follows with reference to the accompanying figures in which:

[0041] [Fig.1] Fig.1 represents a general view of a first system according to the invention, in use and seen from the side in a vertical plane;

[0042] [Fig.2] The [Fig.2] represents the system of the [Fig.1], seen from below;

[0043] [Fig.3] The [Fig.3] represents experimental measurement curves;

[0044] [Fig.4] The [Fig.4] illustrates a comparison between experimentally obtained curves and curves obtained by simulation;

[0045] [Fig.5] The [Fig.5] illustrates curves obtained experimentally for four different materials that have fallen at the same point;

[0046] [Fig.6] The [Fig.6] illustrates the spectral power densities of signals measured for each of the four materials of the [Fig.5];

[0047] [Fig.7] Fig.7 represents a general view of a second system according to the invention, in use and seen from the side in a vertical plane;

[0048] [Fig.8] The [Fig.8] represents the system of the [Fig.7], seen from below;

[0049] [Fig.9] The [Fig.9] illustrates a variant of the system of the [Fig.7];

[0050] [Fig. 10] Figure 10 illustrates a diagram of a method for determining the nature, solid, liquid or soft, of a portion of matter according to the invention and

[0051] [Fig. 11] The [Fig. 11] illustrates a diagram of a method for characterizing a leak according to the invention. DETAILED DESCRIPTION OF THE INVENTION

[0052] First embodiment

[0053] A first embodiment of the present invention is described by means of Figures 1 and 3 and the associated passages below, which describe a leak detection and characterization system 100.

[0054] Figure 1 illustrates an industrial device 50 seen from the side in a vertical plane, beneath which a peripheral element has been placed, which in this example is a containment tray 110 designed to receive portions of material falling from the industrial device due to possible leaks. In this example, liquid falls are considered to be in the form of drops, for example at imperfectly sealed joints. Figure 2 shows a bottom view of the containment tray 110. The containment tray is equipped with an instrumentation kit as described below.

[0055] The containment tray 110 is equipped with vibration sensors 120a, 120d, 120e, and 120f attached to two side walls of the tray, and vibration sensors 120b and 120c attached to the bottom, underneath it in this embodiment. The sensors are preferably attached to the tray walls in such a way as to obtain good mechanical coupling between a sensor and the tray wall to which it is attached, for example, by bonding with a thin layer of adhesive, so that the vibrations transmitted through the tray walls are effectively transmitted to the sensors. More generally, when contact sensors are used (contact sensors are defined as sensors which, by their measurement principle, require a mechanical connection to the peripheral element), they can be attached to the peripheral element, the containment tray in this example, by means of an adhesive (glue, wax) or a mechanical (clamping, screwing, etc.) or magnetic fastening.

[0056] The sensors can each be of the piezoelectric type, each based on one or more piezoelectric elements, possibly formed of a single-crystal piezoelectric thin film extending along an extension plane, less than 50 pm thick and with dimensions greater than 100 pm in its extension plane, as described in French patent application No. FR2303635. Such layers Thin piezoelectric elements are advantageous because their high sensitivity allows them to detect the impact of a falling portion of material, such as a drop of water, on the bottom of the retention tank.

[0057] Each vibration sensor is functionally connected to an electronic computing system 140 comprising a computing unit Cale, a memory Mem, and a clock Clk connected to each other. The system 140 is connected to a human-machine interface Intf such as a control monitor.

[0058] When a leak A occurs, a certain quantity of material falls as a drop from the origin of the leak AOr to a drop point APt located in the containment tank 110, at least approximately directly above the origin of the leak. Upon impact in the containment tank, vibrations AVib are generated at the drop point Apt and then propagate through the walls of the containment tank. These vibrations will be converted by each of the sensors into detection signals sent to the computing system 140, which will process these raw signals using conventional methods to extract detection information, for example, by comparing the amplitude of the detection signals to a threshold in order to eliminate any measurement noise.

[0059] Thus, for each sensor considered independently, the reception of a detection signal by the calculation system can be associated with the occurrence of a leak: in response to the detection signal; the calculation system 140 can calculate a signal associated with the fall, and transmit the corresponding information to an operator by means of the Intf human-machine interface, such as a control monitor or a loudspeaker emitting an alert signal in the event of the detection of a leak.

[0060] At the point of impact Ar, the amplitude of the vibrations AVib depends on the kinetic energy of the droplet, that is, its mass and its height of impact. For a given situation, the volume of a droplet can be defined by the nature of the liquid processed by the industrial device, this volume being determined by the density and viscosity of this liquid. Thus, the signal calculated by the computing system can be representative of the kinetic energy of a droplet that has fallen from the industrial device.

[0061] The calculation device can also be configured to quantify the leak, either by counting the number of detections of a drop occurrence for a given sensor, or by evaluating the quantity of liquid that has fallen based on the amplitude of the detected vibrations. In the second case, this quantity may be determined up to a factor, namely the drop height, but it nonetheless provides information on the quantity of product that has fallen. The quantity of liquid that has fallen can be cumulative (by summation), with each drop being associated with the point in time at which it occurred. The quantity of liquid that has fallen can be related to a time interval. The two preceding options provide an indication of the evolution of the leak's magnitude over time. In this way, the signal calculated by the calculation system can be representative of the occurrence of the leak, but also of a cumulative quantity of material that has fallen from the industrial device, possibly during a given period of time.

[0062] As already mentioned above, the amplitude of the vibrations due to the impact of a drop depends on the nature of the liquid forming the drop and the drop height. The drop height can therefore be deduced from the amplitude of the vibrations due to the impact and the nature of the liquid, and can thus provide information on the height of the leak's origin. Depending on the complexity of the industrial device, this information can prove extremely valuable for locating and treating the leak. In practice, the calculator 140 can be configured to calculate the leak height based on a first signal generated by the sensors equipping the containment tank and a second signal representative of the nature of the liquid processed by the industrial device.

[0063] It is also possible to locate the leak in the horizontal plane, i.e. the position of the drop point in the retention tank, in the most general case by taking advantage of the multiplicity of vibration sensors.

[0064] The applications described above can be applied to a system with only one sensor. Using multiple sensors makes it possible to determine the location of the drop points in the horizontal plane in general cases.

[0065] The high sensitivity of the sensors makes them capable of detecting low amplitude vibrations, and therefore allows their number to be reduced to cover a retention tank of given dimensions.

[0066] The containment basin can be equipped with an anti-vibration system 130 designed to isolate it from vibrations in its environment. The reason for this isolation is that vibrations generated by the operation of the industrial device 50 could interfere with measurements taken using vibration sensors. The anti-vibration system, in this case in the form of anti-vibration mounts, reduces measurement noise and thus improves the reliability of leak detection and location according to the principle detailed below.

[0067] While it is obviously simpler to apply the present invention to a retention tray of simple and regular shape, the retention tray can be of arbitrary shape and dimensions.

[0068] In addition to the containment tray used as an example in this embodiment, all or part of a peripheral element to the industrial device and capable of receiving the material from the point of origin of the leak may be used. This could be, for example, an element in the form of a flat plate, which can be shaped to cover all or part of the footprint of the industrial device.

[0069] The nature of the material used to form the peripheral element and the dimensions of the latter are preferably chosen so that the impact of a portion of material on its surface generates a vibration that can be detected after propagation on the surface of this element.

[0070] A peripheral element can thus be chosen, for example, made of steel, Teflon, glass, ceramic or other material suitable for the environment and the nature of the material falling from the industrial device: a material that is chemically and / or mechanically resistant to material escaping from the industrial device will be chosen preferably, depending on whether it is a corrosive chemical product or a material in the form of blocks whose impact of falling may be sufficient to damage the peripheral element if it is not adequately chosen.

[0071] When the peripheral element takes the form of a plate (for example, the bottom of a containment basin), its thickness is preferably between one and several millimeters, up to one centimeter, or even three or five centimeters; its lateral dimensions depend on the surface area to be covered, but can, for example, extend from 10 cm to 1 m, 2 m, 5 m, or 10 m, or even more. There is no maximum lateral dimension for the peripheral element; the limit is the ability of the sensors to detect a leak, considering that sufficiently sensitive sensors can be used, or multiple sensors can be used to achieve sufficient sensitivity at any point on the peripheral element, or at least at any point considered relevant by the user.However, it is preferable to avoid using a peripheral element whose nature and / or dimensions promote the rapid damping of vibrations generated by the impact of falling material resulting from a leak to be detected or monitored.

[0072] The vibration sensor(s) used can be of various types, such as resistive gauges, piezoelectric gauges, surface microphones, acoustic emission sensors, accelerometers, or even laser vibrometers (which do not need to be fixed in contact with the peripheral element), without any particular limitation, except that the sensitivity or dynamic range of the type of sensor chosen must be adapted to the measurements to be performed. Indeed, the higher the kinetic energy of the portions of material falling due to a leak, due to their weight and fall height, the less critical the sensitivity of the sensors used will be. Therefore, the dynamic range of the sensors will preferably be wide when portions of material with very different weights are likely to fall, depending on the nature of the industrial device being monitored and the type of leak likely to occur.

[0073] Localization of a fall in the horizontal plane

[0074] Figure 1 illustrates a leak A and a leak B, with distinct drop points APt and Br, and origins AOr and Bo, respectively. The drop point Ar is closer to sensor 120b than to sensor 120c, and vice versa for the drop point Ar. Vibrations attenuate with increasing distance from the impact points Ar and Br where they were generated. It is therefore understood that the amplitude of the vibrations AVib of leak A as detected by sensor 120a will be greater than as detected by sensor 120b. Conversely, it is understood that the amplitude of the vibrations BVib of leak B as detected by sensor 120b will be greater than as detected by sensor 120a.

[0075] We see that the information on the vibration amplitudes detected by the different sensors, coupled with the respective locations of these sensors, already provides a first indication of the location of the leaks. The closer the point of a leak is to a sensor, the stronger the vibration amplitude detected by that sensor will be, and if, among the different sensors, the amplitude is maximum for that sensor, then this means that the point of a leak is closest to that sensor, at least to a first approximation.

[0076] In order to more precisely determine the location of drop points, or to optimize the number of vibration sensors required to instrument a peripheral element, it is possible to further analyze the signals generated by these sensors. Several options are available. We will briefly detail three methods for locating drop points by exploiting the sensor signals generated by vibration sensors: arrival time triangulation, modal analysis, and neural network training. Other methods are also possible. But first, we will demonstrate the reproducibility of the vibrations generated by the impacts of falling material on the peripheral element.

[0077] Reproducibility

[0078] Fig. 3 illustrates experimental results carried out with a retention tray used as a peripheral element, a controlled drip system and three vibration sensors SI, S2 and S3, the sensitive element of which is a piezoelectric thin film as already described.

[0079] The experiment consisted of dropping six drops: three times at two distinct positions, designated Pos. 1 and Pos. 2. For each position, each drop is considered an event, the three events being identified as Ev. 1, Ev. 2, and Ev. 3. Figure 3 shows six graphs arranged in two columns and three rows, each graph containing three curves corresponding respectively to the signals generated by the three vibration sensors S1, S2, and S3. Each curve represents The amplitude of a signal over time: the electrical charge in pC generated by a piezoelectric sensor in response to vibrations caused by a drop falling into the retention tray, indicated on the y-axis. Time is indicated in milliseconds on the x-axis. The graphs in the left and right columns correspond respectively to measurements taken at position Pos. 1 and measurements taken at position Pos. 2; the graphs in the top, middle, and bottom rows correspond respectively to measurements taken during events Ev. 1, Ev. 2, and Ev. 3.

[0080] We observe that, for each location, the profiles and amplitudes are repeated almost identically from one fall to the next. Conversely, these profiles are very different from one position to another. Thus, it is clear that signal analysis methods such as those described below will make it possible to deduce the positions of the falls from the signals generated by the vibration sensors.

[0081] Discrimination of the state, whether solid, liquid or soft, of the falling portion of matter

[0082] An impact between a falling portion of material and the peripheral element generates a vibration wave propagating from the point of impact, which will be detected by one or more sensors as explained above. This vibration wave consists of a spectrum of frequencies forming a vibration signature representative of the interaction between the falling material and the surface of the peripheral element. In particular, a first vibration signature of an interaction between the peripheral element and liquid or soft material and a second vibration signature of an interaction between the peripheral element and solid material will be distinct, and will make it possible to determine the state—liquid, soft, or solid—of the material that generated a detected wave. By material in a soft state, or soft material, we mean material in which the interactions between its constituent elements are weak.Soft materials exhibit significant susceptibility to external mechanical stresses and deform easily. Examples of soft materials include foams, gels, elastomers, liquid crystals, cosmetic creams, muds, pastes, and certain food products.

[0083] Figure 5 illustrates graphs similar to those in Figure 3, with curves Measurements were obtained experimentally using three sensors, S1, S2, and S3, for quantities of matter composed of four different materials and dropped at the same point. In [Fig. 5], each curve is associated with the corresponding sensor. Each curve represents the amplitude of a signal over time: the voltage in volts appearing across the terminals of a piezoelectric sensor in response to vibrations caused by a drop falling into the retention tray, indicated on the y-axis. Time is indicated in milliseconds on the x-axis.

[0084] The curves indicated by (A), (B), (C) and (D) were obtained by dropping a bolt, a screw, a drop of water and a silicone pad, respectively.

[0085] It is immediately apparent that the curves obtained for dropped material made of hard materials (bolts and screws, which are made of metals) are very similar. Likewise, the curves obtained for dropped material made of soft materials (liquid water, silicone pad) are also very similar. This observation is confirmed by [Fig. 6].

[0086] Figure 6 illustrates the power spectral density (PSD) of signals measured for each of the four materials in Figure 5: the bolt, the screw, water, and the silicone pad, indicated respectively by Boit, Screw, Water, and Si Pad. The graph in Figure 6 expresses the power spectral density in mV / Hz on the y-axis on a logarithmic scale as a function of frequencies expressed in Hz on the x-axis on a logarithmic scale.

[0087] The overall PSD level is representative of the energy dissipated during impacts, increasing with the mass and velocity of the falling material. For soft or liquid objects, such as a water droplet and a silicone pad, a rapid drop in PSD is observed below 3 x 10⁸ mV / Hz at 10⁴ Hz, and at higher frequencies, from approximately 10² Hz. Conversely, for hard objects, such as a bolt and a screw, the PSD level remains high, above 10⁶ mV / Hz even at 10⁴ Hz.

[0088] It is understood from these findings that measurements of the impacts of matter on the peripheral element by means of vibration sensors make it possible to characterize the state, whether solid, liquid or soft, of the matter.

[0089] For this purpose, the method 400 for determining the nature of the falling material, illustrated by [Fig. 10], can be used. This method comprises the following steps 410 to 450.

[0090] At a step 410, the vibration generated by an impact of a portion of material that has fallen on a peripheral element is measured over a predefined time period around the impact, for example one second, by means of vibration sensors that generate sensor signals.

[0091] At step 420, the average PSDPSD1ow of the measured vibration below a given frequency F and the average PSDPSD1high above this frequency are calculated over a considered frequency range, from 10 Hz to 104 Hz in the example of [Fig. 6]. The given frequency F depends on the characteristics (material, shape, dimensions) of the falling material and the peripheral element. In the example of [Fig. 6], F = 500 Hz may be chosen, since above this frequency, the differences in the signals generated by the falling material are more pronounced than below this frequency, which facilitates the discrimination of the nature of the material.

[0092] At a step 430, a ratio R is calculated between PSDiow and PSDhigh, such that R=PSDiow / PSDhigh, indicative of the distribution of vibrational energy for a given impact between low frequencies and high frequencies.

[0093] At step 440, the calculated ratio R is compared to a threshold value Thr, defined according to the materials likely to fall on the peripheral element. An R ratio greater than Thr indicates a vibration generated by liquid or soft material, favoring the generation of vibrations with relatively more concentrated energy in the low frequencies. Conversely, an R ratio less than Thr indicates a vibration generated by hard material, favoring the generation of vibrations with relatively more concentrated energy in the high frequencies.

[0094] At a step 450, a signal Ss / L is generated, representative of the state, whether solid, liquid or soft, of the material, in response to the comparison of step 440.

[0095] One advantage of the process described above is that the absolute values ​​of the measurements do not have an influence on the ratio R, so this process will work for signals of varying strengths, generated by drops of portions of material of varying weights or from varying heights.

[0096] All the above steps can be carried out automatically without human intervention by the measurement and calculation means of the leak detection and characterization system 100. The ratio R, the frequency F and the threshold value Thr can be defined in advance according to the type of material likely to fall from the industrial device to be monitored, and stored in the Mem memory.

[0097] Such a method can be implemented to detect the nature of a material that has fallen onto the device, particularly when several sources of leakage are possible, involving either solid or liquid materials. This is the case, for example, during the transport of silicon wafers, which are liable to break while being treated with liquid cleaning and / or treatment solutions such as hydrofluoric acid. Method 400 makes it possible to detect whether a detected impact is due to the breakage and fall of a solid silicon wafer or to a liquid leak in the hydrofluoric acid circuit.

[0098] Triangulation of arrival times

[0099] A first method of locating the drop points is that of triangulation of arrival times, described for example by Tobias for the case of impacts on a plate (A. Tobia, “Acoustic-emission source location in two dimensions by an array of three sensors, Non-Destructive Testing 9(1):9-12, February 1976).

[0100] The principle is to use three sensors with known relative positions. If the propagation speed of vibrations in the plate is considered known, then the differences in arrival times between the different sensors can be linked to distances on the plate, and work back to the position of the point of impact using well-known and computationally inexpensive mathematical calculation methods.

[0101] This method, however, has several limitations. A first limitation is that bending waves in plates are dispersive waves, which implies that the high-frequency components will propagate faster than the lower-frequency components. Accurately determining the arrival time is therefore not always easy. The shape of the wave packet generated by the impact changes with the propagation distance; wave attenuation in the structure due to losses in the material will also modify the shape of the wave packet. However, improvements have been proposed to compensate for wave dispersion during propagation and improve accuracy (PD Wilcox, "A rapid signal processing technique to remove the effect of dispersion from guided wave signals", IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, vol. 50, no. 4, pp. 419-427, April 2003).A second limitation is that this method relies on an assumption of structural homogeneity: it is assumed that waves propagate in the same way throughout the entire structure, which is treated as an infinite plate. In practice, the structures studied are often far from this ideal, and the method can lose considerable accuracy. Practitioners should verify that the geometry of the peripheral element they use and the positioning of the sensors are compatible with the triangulation method and the required level of precision.

[0102] Modal analysis

[0103] Modal analysis can provide an alternative to the triangulation method when the latter is not appropriate for a given situation, for example, when the peripheral element's structure is too complex or poorly adapted, for example, due to its shape. Furthermore, the accuracy of calculating arrival times is often better when using the high-frequency components of the vibration signal. Unfortunately, wave attenuation during propagation within the structure is also higher at high frequencies, which limits the distance between the impact point and the sensors for which the method works correctly.

[0104] To overcome these shortcomings, an approach using the low-frequency components of the signal was developed by (D. Goutaudier et al., "Impact localization on a composite fuselage with a sparse network of accelerometers", Volume 348, issue 3 (2020), pp. 191-209), which uses the projection of the impact force onto the modal basis of the structure, truncated to retain only the first eigenmodes. The general idea is that the different modes of the structure are excited in different proportions depending on the location of the impact.

[0105] Learning - Neural Network

[0106] The principle of machine learning methods is to teach a neural network the signal patterns associated with vibrations generated by impacts at different positions. Following this learning, the neural network is able to match a signal or set of signals with the location of the impact that generated that signal or set of signals.

[0107] The main prerequisite for this type of method is to have a training database containing the signals measured by the sensors during impacts at many known locations. The more comprehensive this database, the greater the learning and robustness of the developed models will be. There are essentially two approaches to building this training database.

[0108] The first approach is experimental: sensors are installed and the structure is then impacted at many known locations. This approach can be very time-consuming, and the type of impact possible during training is limited, since they must not damage the structure. An example of this type of approach is explained by Worden and Staszewski (K. Worden and WJ Staszewski, “Impact Location and Quantification on a Composite Panel using Neural Networks and a Genetic Algorithm,” in Strain, Vol. 36 Issue 2, pages 61–68, May 2000).

[0109] The second approach is numerical: a numerical model of the structure is developed, for example by finite elements, and used to simulate various impacts at numerous locations. This database of simulated events is then used for training. If the numerical model is sufficiently accurate, then the performance of the model that learned from the numerical database is good on the real structure. An example of this type of approach is explained by Sahra Sharif Khodaei (Z. Khodaei et al., “Determination of impact location on composite stiffened panels,” in Smart Materials and Structures, IOP Publishing Ltd, Vol. 21, No. 10).

[0110] Figure 4 compares the signal results from three vibration sensors S1, S2, and S3 generated in response to an impact at a given location for an experimental situation in (A) and for a computer-simulated situation in (B). These figures show a very good match between the signals measured by the sensors and the simulated signals. This demonstrates that a digital database can be created through simulation for training the neural network, and that it will not be necessary to create this training database experimentally.

[0111] Second embodiment

[0112] A second embodiment of the invention is described by means of Figures 7 and 8 and the associated passages below, which describe a variant of the first embodiment. The industrial device and the containment tray are different from those of the first embodiment. The other elements constituting system 100 of Leak detection and characterization are identical, except that the number of vibration sensors has been reduced for this second mode.

[0113] Here, as illustrated in side view along a vertical plane by [Fig.7], the industrial device consists of a set of piping 50', under which has been placed a retention tank 110' designed to receive portions of material falling from the industrial device due to possible leaks.

[0114] The specific feature of the present embodiment is that the industrial device is almost one-dimensional, in the sense that the piping extends essentially along one dimension, defined by the longitudinal extension of the piping, along an axis Absc. Figure 8 thus illustrates the retention basin seen from below, significantly longer than it is wide, with, for example, a length L at least five times greater than its width 1.

[0115] In such a case, using three sensors is not mandatory to locate the drop point Cr of a leak C with sufficient precision for an operator to easily determine the origin COr of the leak. Indeed, a simple longitudinal location along the piping is sufficient, and the two sensors 120b and 120c together provide this information: the arrival times associated with the distances dl20b and dl20c separating the drop point CR from sensors 120b and 120c, respectively, are sufficient to determine an abscissa x(Cr) of the drop point Cr along the axis Absc.

[0116] Third embodiment

[0117] Fig. 9 illustrates a third embodiment, here described as based on the second embodiment and its geometry a simplified version of the second embodiment.

[0118] In this embodiment, the quasi-one-dimensional geometry of the retention tank 110' is coupled to the location of a sensor 120ext situated at one end of the retention tank. If we take, for example, the assumption of leaks causing drops of liquid of similar volumes to fall from a pipe of constant height, a simple calibration of the sensor makes it possible to associate a vibration amplitude detected at a distance di20ext from the point Dr of material falling due to a leak D relative to the sensor d^oext, and thus to locate the point of falling by an abscissa x(Dr) equal to the distance di20ext, the origin 0 of the abscissa axis being aligned with the position of the sensor 120ext.

[0119] Fourth embodiment

[0120] Figure 11 is a diagram illustrating a method 500 according to the invention, implemented by means of the system 100 described in the preceding embodiments, having its function is to detect a leak of a portion of material falling from an industrial device.

[0121] At a step 510 of the process, the containment tray 110 or 110' is provided as a peripheral element in the position of the industrial device 50 or 50', from which any leaks are to be detected, the containment tray being equipped with at least one first vibration sensor (120a, 120b, 120c, 120d, or 120ext), and possibly a second, a third and / or other vibration sensors fixed to the containment tray, the vibration sensors being functionally connected to the electronic computing system 140.

[0122] Step 510 may include a step 5140A of instrumenting the peripheral element 110 or 110' with at least one first vibration sensor when this peripheral element is already positioned above the industrial device. Alternatively, step 510 may include a step 510B of instrumenting the peripheral element with at least one first vibration sensor, followed by a step 510C of positioning the instrumented peripheral element above the industrial device.

[0123] A fall of material from the industrial device, caused by a leak, causes an impact at the bottom of the retention tank, this impact in turn causing a vibration which propagates through the walls of the tank.

[0124] At a step 520 of the process, in response to the fall of the portion of material at a drop point (Ar, Br, Cr, Dr) located in the retention tank, the first vibration sensor and optional second and third sensors generate respectively a first, a second and a third sensor signal Scapti, Scapt2, Scapt3 and transmit these sensor signals to the electronic computing system 140, thus performing a measurement of the vibration generated by the impact.

[0125] At a step 530 of the process, in response to the transmission of the sensor signal(s), the electronic computing system generates and emits calculated signals Scaic1, Scaic2, and Scaic3, representing the fall of the portion of material at the drop point located in the retention tray, as perceived by the first, and, where applicable, the second and third sensors, respectively. The calculations may represent the implementation of known methods for locating impact points, as mentioned in the first embodiment.These calculations can also be used to generate signals, each representing one or more of the following information: an occurrence of the fall of the portion of material, a kinetic energy of the portion of material, a cumulative quantity of material that has fallen from the industrial device during a given period of time, a distance between a location of the first vibration sensor and the point where the portion of material falls into the retention tray.

[0126] When any of the calculated signals Scaic1, Scaic2, and Scaic3 are calculated based on the corresponding sensor signal and an SMat signal representative of the nature of the material portion, the calculated signal can at least be representative of a drop height of the material portion, as explained in the section concerning the first embodiment. The SMat signal can be entered manually by an operator or generated by the computer itself based on information stored in the computer memory Mem and representative of the type of material processed by the industrial device and therefore likely to fall into the retention tray.

[0127] At a step 540, on the basis of one or more of the calculated signals Scaici, Scaic2 and SCaic3, i.e. from one or more of the corresponding sensor signals Scapti, Scapt2 and Scapt3, the electronic computing system 140 calculates and emits a position signal Spos representative of a position of the drop point, by means, for example, of one or more of the three methods (triangulation, modal analysis, learning) set out above.

[0128] In parallel with step 530, based on one or more of the sensor signals, process 400 can be implemented, with step 520 replacing step 410.

[0129] Any combination of embodiments one to four is acceptable and falls within the scope of the invention described herein.

[0130] In this description, we have taken the example of material falling in liquid form, but the system and method described by means of these examples also apply to material falling in solid form, possibly in calibrated form when it comes to calculating the height of fall by analogy with the calculation applied to a drop already described.

[0131] The invention is not limited to the embodiments described above and variations thereof may be made without departing from the scope of the invention as defined by the claims.

Claims

Demands

1. Method (400) for detecting a leak (A, B, C, D) of material from an industrial device (50, 50'), comprising the steps of: - measuring (520; 410) a vibration (Avib, Bvib, Cvib) of a peripheral element (110, 110') arranged to receive a portion of material falling from the industrial device (50, 50'); and, - in response to this measurement, and by means of an electronic calculation system (140), generate (530) a calculated signal (Scaici), representative of the fall of the portion of material falling at a drop point (Ar, Br, Cr, Dr) located on the peripheral element (110, 110'), the process being characterized in that the vibration is measured at at least two distinct points of the peripheral element (110, 110'), and, in response to these measurements, the electronic calculation system (140) generates (540) and emits a position signal (Spos) representative of a position of the drop point.

2. A method according to claim 1, further comprising: - a step (510A) of instrumenting the peripheral element (110, 110') with at least a first sensor when this peripheral element is already positioned above the industrial device (50, 50'), or - a step (510B) of instrumenting the peripheral element with at least a first sensor, followed by a step (510C) of positioning the instrumented peripheral element above the industrial device.

3. The method according to any one of claims 1 to 2, wherein the calculated signal is representative of at least one piece of information selected from an occurrence of the fall of the portion of falling material, a kinetic energy of the portion of falling material, a cumulative quantity of material having fallen from the industrial device during a given period of time, a distance between a location of the first sensor and the point of fall of the portion of falling material onto the peripheral element (110, 110'), a state, either solid, liquid or soft, of the portion of falling material.

4. The method according to any one of claims 1 to 3, wherein the calculated signal is calculated on the basis of a vibration detection signal (Scapti) and a signal (SMat) representative of a nature of the portion of matter, the calculated signal being at least representative of a fall height of the portion of matter.

5. The method according to any one of claims 1 to 4, wherein the step of detecting the vibration (Avib, Bvib, Cvib) of the peripheral element (110, 110') is implemented by means of a first vibration sensor comprising a single-crystal piezoelectric thin film extending along an extension plane, less than 50 pm thick and with dimensions greater than 100 pm in its extension plane, this thin film being rigidly attached to the peripheral element.

6. The method according to any one of claims 1 to 5, wherein the peripheral element is a retention tray.

7. Instrumentation kit configured to equip a peripheral element (110, 110') intended to be installed above an industrial device so as to form a system (100) for detecting a leak (A, B, C, D) of material falling from the industrial device (50, 50'), the kit comprising: - at least one vibration sensor (120a, 120b, 120c, 120d, 120ext) intended to generate and emit a sensor signal (Scapti) in response to a vibration (AVib, BVib, CVib) of the peripheral element resulting from an interaction between a portion of the falling material and the peripheral element (130);and - an electronic computing system (140) that can be functionally connected to the first sensor and is intended to, in response to the first sensor signal (Scapti), generate and emit a calculated signal (Scaici) representative of the fall of the portion of material at a drop point (Ar, Br, Cr, Dr) located on the peripheral element, the instrumentation kit being characterized in that it comprises a plurality of vibration sensors (120a, 120b, 120c, 120d) each intended to emit an associated sensor signal (Scapti, Scapt2, Scapt3) in response to the vibration of the peripheral element, and can be functionally connected to the electronic computing system, in which the electronic system is further configured to generate and emit a position signal (Spos) representative of a position of the drop point (Ar, BPt, Cr, DPt), on the basis of the sensor signals (Scapti, Scapt2, Scapt3).

8. The instrumentation kit according to claim 7, wherein the first calculated signal is representative of at least one piece of information selected from an occurrence of the fall of the portion of falling material, a kinetic energy of the portion of falling material, a cumulative quantity of material having fallen from the industrial device during a given period of time, a distance between a location of the first sensor and the point of fall of the portion of falling material onto the peripheral element (110, 110'), a state, either solid, liquid or soft, of the portion of falling material.

9. The instrumentation kit according to claim 7 or 8, wherein the first calculated signal is calculated on the basis of the first sensor signal and a signal (SMat) representative of a nature of the portion of material, the first calculated signal being at least representative of a drop height of the portion of material.

10. The instrumentation kit according to any one of claims 7 to 9, wherein at least one sensor comprises a single-crystal piezoelectric thin film extending along an extension plane, less than 50 pm thick and with dimensions greater than 100 pm in its extension plane.

11. Leak detection system (100) for an industrial device (50, 50') comprising a peripheral element (110, 110') intended to be installed above an industrial device and equipped with the instrumentation kit according to any one of claims 7 to 10.

12. The detection system according to claim 11, further comprising a suspension device (130) configured to isolate the peripheral element from mechanical vibrations from its environment.

13. The detection system according to claim 11 or 12, wherein the peripheral element is a retention tray.

Images