Valve leakage detection method and device

Abstract

The present invention relates to a valve leakage detection method and device, belonging to the field of valve detection technology. In this method, a valve is connected to a flange, and an interferometric fiber optic refractive index sensor is installed on the flange surface. The method comprises: transmitting a first optical signal to a first end of the interferometric fiber optic refractive index sensor, acquiring a second optical signal from a second end of the interferometric fiber optic refractive index sensor, and determining the leakage status of the valve based on the second optical signal. By installing the interferometric fiber optic refractive index sensor on the valve flange surface and detecting the second optical signal from the second end of the interferometric fiber optic refractive index sensor in real time, the present invention can achieve real-time, full-range, in-situ, and highly sensitive monitoring of micro-leakages on the valve flange surface.

Description

Technical Field

[0001] The present invention relates to the technical field of valve detection, and in particular to a valve leakage detection method and device. Background Art

[0002] Valves play a vital role in the storage and transportation of hazardous chemicals. They can seal pipelines, containers and other devices to prevent the leakage of toxic and harmful gases / liquids. However, due to design defects or aging and wear of valves, valve leakage accidents occur frequently, resulting in a large number of casualties and property losses. Therefore, it is necessary to explore valve leakage detection technology. Traditional valve flange surface leakage detection technologies are mostly based on ultrasonic and negative pressure wave detection methods. The ultrasonic detection method requires the installation of multiple ultrasonic sensors, has a limited detection distance, and the maximum leakage monitoring limit is 1L / min. The negative pressure wave method has poor accuracy and is ineffective for detecting small leaks. It has high test limits and cannot monitor leaks caused by sudden release of gas / liquids, nor can it perform real-time monitoring of leaks in small spaces on the flange surface. Summary of the Invention

[0003] In view of this, it is necessary to provide a valve leakage detection method and device to solve the problem in the prior art that leakage in the narrow space of the flange surface cannot be monitored in real time.

[0004] In order to solve the above problems, in a first aspect, the present invention provides a valve leakage detection method, wherein the valve is connected to a flange, and an interferometric fiber optic refractive index sensor is laid on the flange surface of the flange, and the method comprises:

[0005] Transmitting a first optical signal to a first end of the interferometric optical fiber refractive index sensor and acquiring a second optical signal from a second end of the interferometric optical fiber refractive index sensor;

[0006] A leakage condition of the valve is determined according to the second optical signal.

[0007] Optionally, the valve is connected to a target device, the target device includes a target liquid, and the second optical signal includes an initial second optical signal and a current second optical signal; and determining the leakage of the valve according to the second optical signal includes:

[0008] Determining a target light intensity change threshold and a target light phase change threshold based on a target refractive index of the target liquid and a first mapping relationship; wherein the first mapping relationship is a mapping relationship between the refractive index and the light intensity change threshold and the light phase change threshold;

[0009] determining a light intensity variation amplitude and a light phase variation amplitude of the second optical signal according to the initial second optical signal and the current second optical signal;

[0010] When the light intensity variation amplitude is less than or equal to the target light intensity variation threshold, and the light phase variation amplitude is less than or equal to the target light phase variation amplitude, determining that the valve has no leakage;

[0011] When the light intensity variation amplitude is greater than the target light intensity variation threshold, or the light phase variation amplitude is greater than the target light phase variation amplitude, it is determined that the valve is leaking.

[0012] Optionally, the method further includes:

[0013] determining a propagation mode of light in the interferometric optical fiber refractive index sensor based on optical waveguide theory;

[0014] Constructing a physical model of the interferometric optical fiber refractive index sensor based on the finite element method;

[0015] Based on the physical model and the propagation mode, spectral characteristics of light in the interferometric fiber optic refractive index sensor are analyzed when the interferometric fiber optic refractive index sensor is in a liquid medium with a different refractive index; the spectral characteristics include a light intensity change threshold and a light phase change threshold;

[0016] A first mapping relationship between the refractive index and the spectral characteristic is established.

[0017] Optionally, the method further includes:

[0018] The first mapping relationship is calibrated using experimental data.

[0019] Optionally, the target device is a container, and the target liquid is a volatile liquid; the method further includes:

[0020] obtaining a target concentration of the target liquid and a target volume of the target liquid in the container;

[0021] The target light intensity change threshold and the target light phase change threshold are determined according to the target concentration, target volume and the second mapping relationship; wherein the second mapping relationship is the mapping relationship between concentration, volume and the light intensity change threshold and the light phase change threshold.

[0022] Optionally, one side of the flange surface of the flange includes a boss; and the interference type optical fiber refractive index sensor is laid along the edge of the boss.

[0023] Optionally, the interference fiber optic refractive index sensor includes a sensing fiber and a metal capillary wrapping the sensing fiber.

[0024] Optionally, the sensing optical fiber includes at least one target structure; the target structure is a structure in which a single-mode optical fiber, a multi-mode optical fiber and a single-mode optical fiber are connected in sequence; the metal capillary includes at least one hole, and the position of the hole corresponds to the position of the multi-mode optical fiber.

[0025] Optionally, the interference type optical fiber refractive index sensor is laid on the target device along the flow direction of the target liquid when it leaks.

[0026] In a second aspect, the present invention further provides a valve leakage detection device, comprising:

[0027] an optical signal acquisition module, configured to transmit a first optical signal to a first end of an interferometric optical fiber refractive index sensor and acquire a second optical signal from a second end of the interferometric optical fiber refractive index sensor; wherein the interferometric optical fiber refractive index sensor is laid on a flange surface of a flange connected to the valve;

[0028] A leakage condition determination module is configured to determine a leakage condition of the valve according to the second optical signal.

[0029] The beneficial effects of the present invention are:

[0030] The present invention lays an interferometric fiber optic refractive index sensor on the flange surface of a flange connected to the valve, emits a first optical signal to the first end of the interferometric fiber optic refractive index sensor in real time, detects a second optical signal at the second end of the interferometric fiber optic refractive index sensor, and determines the leakage of the valve based on the second optical signal. By utilizing the highly sensitive interferometric fiber optic refractive index sensor on the flange surface, real-time, full-area, in-situ, and highly sensitive monitoring of micro-leakage on the valve flange surface can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic flow chart of an embodiment of a valve leakage detection method provided by the present invention;

[0032] Figure 2 A schematic diagram of the structure of a sensing optical fiber provided by the present invention;

[0033] Figure 3 This is a schematic structural diagram of an interferometric optical fiber refractive index sensor provided by the present invention;

[0034] Figure 4 1 is a structural diagram of an embodiment of a valve leakage detection system provided by the present invention;

[0035] Figure 5 This is a schematic diagram of a liquid micro-leakage detection experimental device provided by the present invention;

[0036] Figure 6This is a spectrum diagram before liquid leakage in the detection experiment provided by the present invention;

[0037] Figure 7 This is a spectrum diagram of the liquid leaked 5 seconds after the detection experiment provided by the present invention;

[0038] Figure 8 A schematic structural diagram of an embodiment of a valve leakage detection device provided by the present invention;

[0039] 1-Single-mode optical fiber; 2-Multimode optical fiber; 3-Hole; 4-Metal capillary. DETAILED DESCRIPTION

[0040] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making any creative efforts shall fall within the scope of protection of the present invention.

[0041] In the description of the embodiments of the present invention, unless otherwise specified, “plurality” means two or more. “First”, “second”, etc. involved in the embodiments of the present invention are used to distinguish similar objects, and are not used to describe a specific order or precedence, nor are they used to indicate or imply their relative importance or implicitly indicate the number of technical features indicated. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application can be implemented in an order other than those illustrated or described herein, and the objects distinguished by “first”, “second”, etc. are generally of one type, and the number of objects is not limited. For example, the first object can be one or more.

[0042] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present invention. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute a separate or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0043] Reference Figure 1 , shows a flow chart of an embodiment of a valve leakage detection method provided by the present invention, wherein the valve is connected to a flange, and an interferometric fiber optic refractive index sensor is laid on the flange surface. The method includes:

[0044] S101 , transmitting a first optical signal to a first end of an interferometric optical fiber refractive index sensor, and acquiring a second optical signal from a second end of the interferometric optical fiber refractive index sensor.

[0045] S102: Determine the leakage status of the valve according to the second optical signal.

[0046] A flange is a type of connector used to connect pipes, valves, pumps, and other equipment in a piping system. The flange face refers to the contact surface of the flanges of the two flanges in a flange connection.

[0047] An interferometric fiber optic refractive index sensor uses fiber optic interferometry to measure the refractive index of the medium surrounding the optical fiber. This sensor indirectly measures the refractive index change of the medium by detecting the interference of light waves in the optical fiber.

[0048] When the valve is connected to other equipment through two flanges, there is a gap between the flange surfaces of the two flanges. The interferometric fiber optic refractive index sensor has a small diameter and can be laid on the flange surface of the flange connected to the valve.

[0049] When leakage occurs at the connection between the valve and the flange, the refractive index of the narrow space between the flange surfaces changes, causing the second optical signal to change relative to the first optical signal. Therefore, by monitoring the second optical signal, the leakage of the valve can be determined.

[0050] The embodiment of the present invention lays an interferometric fiber optic refractive index sensor on the flange surface of the flange connected to the valve and utilizes the high sensitivity of the interferometric fiber optic refractive index sensor to achieve real-time, full-area, in-situ, and highly sensitive monitoring of flange surface micro-leaks at the 1 mL / min level, breaking through the bottleneck problems of insufficient accuracy and low sensitivity in current flange surface micro-leakage monitoring technology.

[0051] In one embodiment, the valve is connected to a target device, the target device includes a target liquid, and the second light signal includes an initial second light signal and a current second light signal; wherein the initial second light signal refers to the second light signal detected when no leakage occurs; then S102 may specifically include: determining a target light intensity change threshold and a target light phase change threshold based on a target refractive index of the target liquid and a first mapping relationship; wherein the first mapping relationship is a mapping relationship between the refractive index and the light intensity change threshold and the light phase change threshold; determining a light intensity change amplitude and a light phase change amplitude of the second light signal based on the initial second light signal and the current second light signal; when the light intensity change amplitude is less than or equal to the target light intensity change threshold, and the light phase change amplitude is less than or equal to the target light phase change amplitude, determining that the valve has no leakage; when the light intensity change amplitude is greater than the target light intensity change threshold, or the light phase change amplitude is greater than the target light phase change amplitude, determining that the valve has leaked.

[0052] The refractive index of the medium surrounding the interferometric fiber optic refractive index sensor varies, affecting the second optical signal in varying ways. Therefore, different medium refractive indices correspond to different light intensity and phase change thresholds. The first mapping relationship between the medium refractive index and the light intensity and phase change thresholds can be determined in advance through experimental testing or simulation.

[0053] When the target device connected to the valve includes a target liquid, the corresponding target light intensity change threshold and target light phase change threshold can be determined based on the refractive index of the target liquid. Then, based on the actually monitored light intensity change amplitude, light phase change amplitude, target light intensity change threshold and target light phase change threshold, it can be judged whether the target liquid leaks at the flange surface.

[0054] For example, take a liquefied natural gas (LNG) leak:

[0055] An interferometric fiber optic refractive index sensor is mounted on the flange surface. Initially, there is no liquefied natural gas (LNG) present in the environment. A laser emits a first light signal, which enters the first end of the interferometric fiber optic refractive index sensor. When no leaks occur, the second light signal received at the second end of the interferometric fiber optic refractive index sensor has an intensity of 1000 mV and a stable phase of 0°.

[0056] Suppose a liquefied natural gas (LNG) leak occurs. Compared to air, the refractive index of LNG is approximately 1.20. The laser continues to emit the first optical signal, which propagates through the interferometric fiber optic refractive index sensor. As LNG penetrates, the refractive index of the medium surrounding the sensor changes, altering the interference pattern of the second optical signal. At this point, the received second optical signal's intensity may drop to 600 mV, with a phase shift of 15°. Data analysis reveals significant changes in the interference fringes, increased fluctuations in the second optical signal, and instability. By comparing the parameters of the second optical signal before and after the leak, thresholds can be set to determine if a leak has occurred. For example, if the second optical signal's intensity drops by more than 30% (from 1000 mV to 600 mV) or the phase shift exceeds 10° (from 0° to 15°), the system can automatically trigger an alarm, indicating a risk of LNG leak.

[0057] In one embodiment, the valve leakage detection method further includes: determining a propagation mode of light in an interferometric fiber optic refractive index sensor based on optical waveguide theory; constructing a physical model of the interferometric fiber optic refractive index sensor based on a finite element method; analyzing, based on the physical model and the propagation mode, the spectral characteristics of light in the interferometric fiber optic refractive index sensor when the interferometric fiber optic refractive index sensor is in liquid media with different refractive indices; the spectral characteristics include a light intensity change threshold and a light phase change threshold; and establishing a first mapping relationship between the refractive index and the spectral characteristics.

[0058] Optical waveguide theory describes the propagation behavior of light in optical fibers, including mode propagation, refractive index distribution, and phase changes. The refractive index distribution of optical fibers is a key factor influencing light propagation. In interferometric sensors, small changes in the refractive index result in altered interference fringes, indicating the presence of liquid in the environment.

[0059] The finite element method (FEM) is a numerical analysis technique used to solve complex engineering and physics problems. FEM can simulate the structural characteristics and light propagation behavior of optical fibers, thereby analyzing the impact of changes in the refractive index of the surrounding medium on optical signals.

[0060] In this embodiment, the interferometric fiber optic refractive index sensor may include a sensing fiber, which includes at least one target structure; the target structure is a structure in which a single-mode fiber, a multimode fiber, and a single-mode fiber are sequentially connected. The process of constructing the first mapping relationship may specifically include:

[0061] First, build a model of the sensing fiber and define the geometric characteristics of single-mode and multimode fibers, such as core diameter, cladding diameter, and refractive index distribution. Set the refractive index of the fiber material and define the refractive index range of the liquid.

[0062] Next, light propagation is simulated using optical waveguide theory to calculate the propagation modes supported within the optical fiber, including the fundamental mode and higher-order modes. Modes are solved using MATLAB or other numerical calculation software to obtain the mode propagation constants and light field distribution. A physical model of the sensing fiber is constructed using FEM software (such as COMSOL Multiphysics), defining boundary conditions and material properties. The fiber is meshed, ensuring a sufficiently fine mesh along the light propagation path to capture subtle variations in light. The light field distribution within the fiber is solved using FEM, analyzing the changes in light field distribution caused by changes in the liquid's refractive index and identifying key parameters related to the refractive index.

[0063] Finally, the changes in the light field distribution are analyzed, and the interference patterns under different refractive index conditions are calculated. The changes in the interference signal intensity and phase under different ambient medium refractive indices are compared, and their relationship with leakage is analyzed and a mathematical model is constructed, that is, the first mapping relationship is constructed.

[0064] In this embodiment, a first mapping relationship between the refractive index and the spectral characteristic is established through simulation testing.

[0065] In one embodiment, the first mapping relationship may also be corrected using experimental data to ensure consistency between simulation tests and experimental tests.

[0066] In one embodiment, the target device may be a container storing a target liquid, which is a volatile liquid. The valve leakage detection method may further include: obtaining a target concentration of the target liquid and a target volume of the target liquid in the container; determining a target light intensity change threshold and a target light phase change threshold based on the target concentration, the target volume, and a second mapping relationship. The second mapping relationship is a mapping relationship between concentration, volume, and the light intensity change threshold and the light phase change threshold.

[0067] Different concentrations and / or volumes of the target liquid in the container will affect the saturation of the target liquid in the air after evaporation. Different saturations of volatile gases in the air also lead to different refractive indices, which in turn cause changes in the second optical signal. When the target liquid is a volatile liquid such as liquid ammonia, a large amount of volatile gases will escape at the beginning of a leak, changing the refractive index of the ambient gas surrounding the interferometric fiber optic refractive index sensor and causing a change in the spectral signal. Therefore, based on the target concentration and volume of the target liquid and the second mapping relationship, target light intensity change thresholds and target light phase change thresholds are determined. Based on these target light intensity change thresholds and target light phase change thresholds, a valve leak can be determined, enabling early-stage leak monitoring.

[0068] In one embodiment, the interferometric fiber optic refractive index sensor includes a sensing fiber and a metal capillary tube encapsulating the sensing fiber. The metal capillary tube can ensure the reliability and durability of the sensing fiber.

[0069] In one embodiment, the sensing optical fiber includes at least one target structure; the target structure is a structure in which a single-mode optical fiber, a multimode optical fiber, and a single-mode optical fiber are sequentially connected; and the metal capillary includes at least one hole, the position of the hole corresponding to the position of the multimode optical fiber. The hole in the metal capillary can be processed using a laser punch. The position of the hole corresponds to the position of the multimode optical fiber, thereby allowing liquid to enter the metal capillary and reach the multimode optical fiber, allowing the sensing optical fiber to detect changes in the environment or medium outside the multimode optical fiber. At the same time, the hole can block the intrusion of large particles or contaminants, protecting the sensing optical fiber from damage, and preventing optical signal loss caused by direct contact, thereby maintaining the optical performance of the sensor.

[0070] Reference Figure 2 , shows a schematic diagram of the structure of a sensing optical fiber provided by the present invention. The two ends of the multimode optical fiber 2 are respectively connected to the single-mode optical fiber 1. The propagation mode of light in the multimode optical fiber 2 is a leakage mode. The leakage mode refers to the light wave propagating in the optical fiber, and its energy is not only concentrated in the core of the optical fiber, but also partially leaks into the cladding of the optical fiber. Therefore, even a slight change in the refractive index of the ambient medium will cause the attenuation or phase shift of the leakage mode, so that the ambient medium can be detected. By monitoring the changes in the leakage mode, the specific location of the leak can be determined. The propagation mode of light in the single-mode optical fiber 1 is a guided mode. The guided mode refers to the light wave propagating in the optical fiber, and its energy is mainly concentrated in the core of the optical fiber and propagates along the axial direction of the optical fiber. The guided mode provides a reference signal for comparison with the signal changes of the leakage mode. This can effectively filter out background noise and enhance the accuracy of detection.

[0071] The preparation method for sensing optical fibers can include first removing the coating from single-mode fiber (SMF) and multi-mode fiber (MMF), then slitting the SMF and MMF end faces flat, and finally fusing a section of MMF between two standard SMFs to create an SMS (single-mode-multi-mode-single-mode) structure. The SMS cladding is then etched away in an HF solution to produce a declad SMS sensing fiber.

[0072] When the incident light signal enters the multimode fiber from the single-mode fiber, the leakage mode light signal of the multimode fiber segment couples with the ambient medium and is modulated by the refractive index of the medium.

[0073] When the leaky mode optical signal in a multimode fiber segment couples with the ambient medium, the phase difference between the optical signals in different modes is:

[0074]

[0075] In the formula is the phase difference between the m-th order modes in the MMF; —Equivalent refractive index of the mth-order mode; is the equivalent refractive index of the nth-order mode; is the wavelength of light in vacuum; is the length of the multimode fiber in the SMS structure; is the equivalent refractive index difference between the m-th order mode and the n-th order mode in a multimode fiber.

[0076] when When the peak of the transmission spectrum meets the conditions of destructive interference (corresponding to the trough of the spectrum line), the peak wavelength (trough wavelength) of the destructive interference is:

[0077]

[0078] In the above formula, the wavelength interval between two adjacent interference minima is approximately:

[0079]

[0080] When the refractive index of the test liquid increases, the equivalent refractive index difference of different excitation modes It also increases, and the wavelength interval between two adjacent interference minima increases.

[0081] Reference Figure 3 , which shows a schematic structural diagram of an interferometric fiber optic refractive index sensor provided by the present invention. The sensing fiber can be placed inside a metal capillary 4, with the hole 3 on the metal capillary 4 facing the position of the multimode fiber.

[0082] In one embodiment, one side of the flange surface of the flange includes a boss; an interference type optical fiber refractive index sensor can be laid along the edge of the boss.

[0083] Reference Figure 4 , showing a schematic diagram of the structure of an embodiment of a valve leakage detection system provided by the present invention. According to the characteristics of the standard sealing flange of hazardous chemical tanks, the flange face boss of the flange is 1mm higher than the flange face, and the standard sealing gasket thickness is 3mm. The key to flange sealing is that the connecting bolts provide pre-tightening force to achieve an extrusion connection between the flange face and the gasket. The main reasons for flange sealing failure are loose bolts, flange rupture, gasket damage, etc. By analyzing the structure of the sealing flange and the liquid leakage path caused by failure, a design is designed. Figure 4The flange-mounted interferometric fiber optic refractive index sensor utilizes a metal capillary tube to protect the sensing fiber and weld it to the flange surface. This design protects the sensing fiber while minimizing interference from extraneous parameters. The sensor and capillary tube have small diameters and a compact structure, making them suitable for flange seal monitoring on a variety of standard components. The sensor's sensitive area (multimode fiber area) is enclosed and secured within the metal capillary tube. A leak hole is created in the inner wall of the capillary tube to allow liquid to enter the hole and contact the sensing fiber, triggering a leak response. A sufficient length of single-mode fiber is fused to each end of the fiber's sensitive area to connect to a light source and spectrometer for signal transmission.

[0084] In one embodiment, interferometric fiber optic refractive index sensors can be placed on the target device along the flow direction of the target liquid when it leaks, to monitor potential leak points. For example, the target device is a vertically positioned pipeline containing liquid, connected to a valve via a flange. Analysis has shown that if a leak occurs at the flange, the leaked liquid will flow vertically down the outer wall of the pipeline. Therefore, interferometric fiber optic refractive index sensors can be placed along the outer wall of the pipeline where the leaked liquid is likely to flow.

[0085] Reference Figure 5 , showing a schematic diagram of an experimental setup for liquid microleak detection provided by the present invention. This experiment uses a standard DN25 flange with a 4-inch external thread. A metal capillary with an outer diameter of 3mm is welded to the flange surface. A sensing fiber is encapsulated within the metal capillary, one end of which is connected to a light source and the other to a spectrometer. The two flanges are connected to a 30cm and a 15cm section of custom transparent pipe with a 4-inch internal thread, respectively, to connect the two custom transparent pipes. The custom transparent pipes have a 3mm wall thickness and are marked with a liquid level height scale on the outer wall to facilitate calculation of liquid leakage rate. A gasket is located between the two flanges, with a crack on the gasket, which serves as a leakage path. The experimental setup is secured with an iron stand. Liquid is injected from above the custom transparent pipes, and the spectrometer on the spectrometer indicates leakage at the crack. This experiment investigates the response of an interferometric fiber optic refractive index sensor when a gasket damages the flange at the connection, causing a liquid microleak. This simulation simulates the monitoring and early warning of microleakage in flange-sealed tanks in hazardous chemical transport tank trucks.

[0086] Reference Figure 6 , which shows the spectrum diagram before liquid leakage in the detection experiment provided by the present invention. Figure 6 In the spectrum, the horizontal axis is the wavelength of light, which is from 1549nm to 1570nm, and the vertical axis is the intensity of light. Figure 7 , shows the spectrum diagram of the liquid leaking 5 seconds after the detection experiment provided by the present invention. Figure 7In the spectrum, the horizontal axis represents the wavelength of light, which ranges from 1549 nm to 1570 nm, and the vertical axis represents the intensity of light. During the experiment, due to the small gasket crack, when the liquid was injected at a low depth, the liquid pressure around the crack was low, and no leakage occurred. This phenomenon can be observed by observing the changes in the spectrum during liquid injection. As the liquid level continued to rise, the spectrum on the spectrometer initially remained unchanged, then shifted to the lower right, indicating that leakage only occurred when the liquid was injected to a certain depth. Monitoring a transmission trough showed a 3dBm drop in intensity at a leakage rate of 4.8 ml / min, with an instrument response time of 5 seconds. This experiment, through the construction of the corresponding experimental setup and leakage simulation, verified the feasibility of using an interferometric fiber optic refractive index sensor on the flange surface for real-time, global, in-situ, and highly sensitive monitoring of micro-leaks on the flange surface.

[0087] Reference Figure 8 , shows a schematic structural diagram of an embodiment of a valve leakage detection device provided by the present invention, wherein the device 80 comprises:

[0088] an optical signal acquisition module 801 configured to transmit a first optical signal to a first end of an interferometric optical fiber refractive index sensor and acquire a second optical signal from a second end of the interferometric optical fiber refractive index sensor; wherein the interferometric optical fiber refractive index sensor is disposed on a flange surface of a flange connected to a valve;

[0089] The leakage condition determination module 802 is configured to determine the leakage condition of the valve according to the second optical signal.

[0090] It should be noted that the implementation principles or implementation processes of the above modules can refer to the embodiments of the above-mentioned valve leakage detection method, and will not be described in detail here.

[0091] Those skilled in the art will appreciate that all or part of the process steps of the above-described embodiments can be implemented by instructing related hardware through a computer program, and the program can be stored in a computer-readable storage medium, such as a magnetic disk, an optical disk, a read-only memory, or a random access memory.

[0092] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A valve leakage detection method, characterized in that: The valve is connected to a flange, and an interferometric optical fiber refractive index sensor is laid on the flange surface of the flange. The method includes: Transmitting a first optical signal to a first end of the interferometric optical fiber refractive index sensor and acquiring a second optical signal from a second end of the interferometric optical fiber refractive index sensor; determining a leakage condition of the valve according to the second optical signal; The valve is connected to a target device, the target device includes a target liquid, and the second optical signal includes an initial second optical signal and a current second optical signal; and determining the leakage of the valve according to the second optical signal includes: Determining a target light intensity change threshold and a target light phase change threshold according to a target refractive index of the target liquid and a first mapping relationship; wherein the first mapping relationship is a mapping relationship between the refractive index and the light intensity change threshold and the light phase change threshold; determining a light intensity variation amplitude and a light phase variation amplitude of the second optical signal according to the initial second optical signal and the current second optical signal; When the light intensity variation amplitude is less than or equal to the target light intensity variation threshold, and the light phase variation amplitude is less than or equal to the target light phase variation amplitude, determining that the valve has no leakage; When the light intensity variation amplitude is greater than the target light intensity variation threshold, or the light phase variation amplitude is greater than the target light phase variation amplitude, it is determined that the valve is leaking.

2. The valve leakage detection method according to claim 1, characterized in that: The method further comprises: determining a propagation mode of light in the interferometric optical fiber refractive index sensor based on optical waveguide theory; Constructing a physical model of the interferometric optical fiber refractive index sensor based on the finite element method; Based on the physical model and the propagation mode, spectral characteristics of light in the interferometric fiber optic refractive index sensor are analyzed when the interferometric fiber optic refractive index sensor is in a liquid medium with a different refractive index; the spectral characteristics include a light intensity change threshold and a light phase change threshold; A first mapping relationship between the refractive index and the spectral characteristic is established.

3. The valve leakage detection method according to claim 2, characterized in that: The method further comprises: The first mapping relationship is calibrated using experimental data.

4. The valve leakage detection method according to claim 1, characterized in that: The target device is a container, and the target liquid is a volatile liquid; the method further includes: obtaining a target concentration of the target liquid and a target volume of the target liquid in the container; The target light intensity change threshold and the target light phase change threshold are determined according to the target concentration, target volume and the second mapping relationship; wherein the second mapping relationship is the mapping relationship between concentration, volume and the light intensity change threshold and the light phase change threshold.

5. The valve leakage detection method according to claim 1, characterized in that: One side of the flange surface of the flange includes a boss; the interference type optical fiber refractive index sensor is laid along the edge of the boss.

6. The valve leakage detection method according to claim 1, characterized in that: The interference type optical fiber refractive index sensor includes a sensing optical fiber and a metal capillary wrapping the sensing optical fiber.

7. The valve leakage detection method according to claim 6, characterized in that: The sensing optical fiber includes at least one target structure; the target structure is a structure in which single-mode optical fiber, multi-mode optical fiber and single-mode optical fiber are connected in sequence; the metal capillary includes at least one hole, and the position of the hole corresponds to the position of the multi-mode optical fiber.

8. The valve leakage detection method according to claim 1, characterized in that: The interference type optical fiber refractive index sensor is laid on the target device along the flow direction of the target liquid when it leaks.

9. A valve leakage detection device, characterized in that: include: an optical signal acquisition module, configured to transmit a first optical signal to a first end of an interferometric optical fiber refractive index sensor and acquire a second optical signal from a second end of the interferometric optical fiber refractive index sensor; wherein the interferometric optical fiber refractive index sensor is laid on a flange surface of a flange connected to the valve; a leakage condition determination module, configured to determine a leakage condition of the valve according to the second optical signal; The valve is connected to a target device, the target device includes a target liquid, and the second optical signal includes an initial second optical signal and a current second optical signal; and determining the leakage of the valve according to the second optical signal includes: Determining a target light intensity change threshold and a target light phase change threshold according to a target refractive index of the target liquid and a first mapping relationship; wherein the first mapping relationship is a mapping relationship between the refractive index and the light intensity change threshold and the light phase change threshold; determining a light intensity variation amplitude and a light phase variation amplitude of the second optical signal according to the initial second optical signal and the current second optical signal; When the light intensity variation amplitude is less than or equal to the target light intensity variation threshold, and the light phase variation amplitude is less than or equal to the target light phase variation amplitude, determining that the valve has no leakage; When the light intensity variation amplitude is greater than the target light intensity variation threshold, or the light phase variation amplitude is greater than the target light phase variation amplitude, it is determined that the valve is leaking.

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