Distributed fiber based supercritical co2 pipeline leak detection method and apparatus

Abstract

The application discloses a supercritical CO2 pipeline leakage detection method and device based on distributed optical fibers, and the method comprises the following steps: uniformly laying three temperature sensing optical fibers around the supercritical CO2 pipeline, and the direction of each temperature sensing optical fiber is along the pipeline trend; emitting laser pulse signals into each temperature sensing optical fiber through a laser source, and the laser pulse signals generate reflected light sensing signals in the form of backward Raman scattering during the transmission process; acquiring temperature signals of the temperature sensing optical fibers at each detection point along the supercritical CO2 pipeline through an optical fiber temperature detection host based on the reflected light sensing signals; comprehensively judging whether the supercritical CO2 pipeline leaks according to the temperature signals of each detection point, including judging abnormal temperature signals and judging the leakage point of the supercritical CO2 pipeline. The application can effectively detect the leakage of the supercritical CO2 pipeline for a long time, and the detection precision is high.

Description

Technical Field

[0001] This invention relates to the field of supercritical CO2 pipeline detection technology, specifically to a method and apparatus for detecting leaks in supercritical CO2 pipelines based on distributed optical fibers. Background Technology

[0002] Currently, the main methods of transporting CO2 are transportation and pipeline transport. Transportation involves compressing CO2 into a solid or liquid state, packaging it in containers, and then transporting it. Pipeline transport utilizes CO2 pipelines for transportation. For short-term CO2 transport, transportation is more economical, while for long-term transport, pipelines are more efficient. Pipeline transport of CO2 is a crucial step in achieving CCUS (Supercritical CO2 System), and supercritical CO2 pipelines play an increasingly important role. Pressurizing CO2 to a supercritical state is the most economical transportation method. In this state, CO2 not only has a high density similar to a liquid but also possesses high diffusivity and low viscosity similar to a gas, allowing for large-scale and rapid transport. Even when buried underground, supercritical CO2 pipelines are still affected by factors such as meteorological disasters, geological movements, and human activities. Furthermore, a leak in a CO2 pipeline directly impacts the environment near the leak point: the leakage of high-pressure CO2 gas generates a huge impact force, damaging the surrounding environment; the temperature at the leak point drops sharply, harming organisms in the surrounding area and potentially causing secondary accidents. Furthermore, because CO2 is denser than air, the CO2 concentration in the surrounding area rises rapidly after a pipeline leak. If this concentration accumulates for a long time in relatively low-lying areas, it can cause suffocation hazards to the local flora and fauna. Therefore, understanding the operating status of supercritical CO2 pipelines can not only effectively prevent external damage to the pipelines but also promptly identify pipeline faults and quickly carry out repairs, ensuring the safe operation of supercritical CO2 pipelines.

[0003] In the actual operation of supercritical CO2 pipelines, the traditional method for detecting the operating status of CO2 pipelines is to use drones to patrol a certain area. Currently, the commonly used hardware-based leak detection methods are mainly negative pressure wave method, infrasound method, etc.; Yuan Wenqiang, Lang Xianming, Cao Jiangtao, et al. Research progress of pipeline leak detection technology based on acoustic wave method [J]. Oil & Gas Storage and Transportation, 2023, 42(02): 141-151. Using acoustic wave method to detect pipeline leak status, since the transmission medium of sound wave has a great influence on the propagation of sound wave, when the pipeline leak is small or the fluid has a high elastic coefficient, viscosity or density, it will be impossible to detect due to insufficient sensitivity. Gao Lin, Cao Jianguo. A review of pipeline leak detection methods [J]. Modern Manufacturing Engineering, 2022, No. 497(02): 154-162. This paper describes the pipeline leak detection methods, and focuses on the research progress of leak signal identification and location processing methods, but does not focus on the detection of supercritical CO2 pipelines.

[0004] In summary, existing detection methods have many shortcomings, lack efficient and economical detection means, and cannot effectively detect supercritical CO2 pipeline leaks in the long term. Summary of the Invention

[0005] The purpose of this invention is to provide a method and device for detecting leaks in supercritical CO2 pipelines based on distributed optical fibers. Distributed optical fiber sensors are laid at specific locations around the supercritical CO2 pipeline to achieve comprehensive monitoring of the pipeline's operating status, solving various problems such as high labor costs, long time cycles, and insufficient sensitivity in traditional supercritical CO2 pipeline inspections. This invention can effectively detect leaks in supercritical CO2 pipelines over a long period with high accuracy.

[0006] This invention is achieved through the following technical solution:

[0007] In a first aspect, the present invention provides a method for detecting leaks in supercritical CO2 pipelines based on distributed optical fibers, the method comprising:

[0008] Three temperature-sensing optical fibers are laid around the supercritical CO2 pipeline, and the direction of each temperature-sensing optical fiber is along the pipeline.

[0009] Laser pulse signals are emitted into each temperature-sensing fiber by a laser source. During the transmission process, the laser pulse signals excite photons and light molecules in the temperature-sensing fiber, causing inelastic collisions and generating reflected light sensing signals in the form of backscattering Raman scattering.

[0010] Based on reflected light sensing signals, the temperature signals of each detection point along the supercritical CO2 pipeline are obtained by the fiber optic temperature detection host.

[0011] Based on the temperature signals from each detection point, a comprehensive judgment is made as to whether a leak has occurred in the supercritical CO2 pipeline, including judging abnormal temperature signals and determining the leak point in the supercritical CO2 pipeline.

[0012] In the above technical solution, if a leak occurs in the CO2 delivery pipeline during the detection process, the leaking part will eject low-temperature CO2 gas to the outside, affecting the temperature of the surrounding environment and causing it to drop rapidly. The optical fiber at the corresponding location will sense the temperature change, and at the same time, it will cause the backscattered Raman light to interfere. The optical fiber temperature detection host receives the interference result of the returned Raman scattered light and determines whether a leak has occurred at that location by comparing it with the normal signal already recorded in the host.

[0013] Furthermore, three temperature-sensing optical fibers are uniformly laid around the supercritical CO2 pipeline, with each fiber oriented along the pipeline's direction, specifically:

[0014] One optical fiber is laid directly below, to the upper left and to the upper right of the supercritical CO2 pipeline along the pipeline's direction.

[0015] Furthermore, the distance between each temperature-sensing optical fiber and the supercritical CO2 pipeline is equal and is 15cm.

[0016] Furthermore, the identification of abnormal temperature signals includes:

[0017] Based on the temperature signals from each detection point, the temperature signals from each detection point are compared with the preset temperature signals of each detection point stored in the fiber optic temperature detection host. If there is a difference, it is an abnormal temperature signal; otherwise, it is a normal temperature signal.

[0018] Furthermore, determining the leak point in a supercritical CO2 pipeline includes:

[0019] The distributed temperature-sensing optical fiber is divided into segments at fixed intervals (e.g., 1.5m) to obtain several segments, and each segment serves as a detection point.

[0020] The leak point of the supercritical CO2 pipeline is determined by comparing the absolute value of the temperature difference between adjacent detection points with the preset set threshold.

[0021] If the absolute value of the temperature difference between all adjacent detection points All are less than the preset setting threshold. ,Right now If all detection points are normal, then it is determined that there are no leaks.

[0022] If the absolute value of the temperature difference between adjacent detection points Greater than the preset setting threshold ,Right now If the temperature difference around the i-th detection point is not abnormal, then it is determined that there is a leak point in the segment of the detection point.

[0023] Furthermore, the absolute value of the temperature difference between adjacent detection points = , , The temperature values ​​of two adjacent detection points;

[0024] Preset setting threshold ,in, Temperature compensation is used to avoid the impact on measurement accuracy; it can be set to 1℃. This is to avoid the influence of external temperature changes along the axial direction of the pipeline, and the temperature compensation can be taken as 1~3℃. This is to compensate for the temperature difference caused by the uneven distribution of its own insulation layer. This part can be moderately compensated through long-term monitoring. After compensation, it can be taken as 1~2℃. This is the reliability margin temperature, which can be taken as 1~2℃.

[0025] Furthermore, determining the leak point in a supercritical CO2 pipeline also includes:

[0026] Based on the temperature difference between the detection point and surrounding detection points, the distance between the leak point and the detection point is determined, thus obtaining the location of the leak point.

[0027] The distance between the leak point i and the first detection point is L = (i-1) × fixed distance, for example, the fixed distance is 1.5m.

[0028] Furthermore, a comprehensive assessment of whether a supercritical CO2 pipeline has leaked also includes:

[0029] V1: The real-time reflected light sensing signal is processed by the signal analysis module to obtain the corresponding temperature data;

[0030] V2: Performs data-level fusion of multi-source heterogeneous data from supercritical CO2 pipelines and matches them using data association rules; the multi-source heterogeneous data includes real-time monitoring data, historical monitoring data, transmission medium data, and environmental data, etc.

[0031] V3: Real-time monitoring of temperature data from supercritical CO2 pipelines includes anomaly detection and removal, as well as steady-state screening.

[0032] The normal threshold temperature T around the CO2 pipeline is denoted as T. rang =[T min T max The temperature of supercritical CO2 inside the pipe is T. c T min >T c ; denoted as the real-time temperature value T obtained at the i-th detection point of the distributed optical fiber. i , ;

[0033] When T i <T c or T i >T max If the temperature data is abnormal, it will be discarded.

[0034] Furthermore, the temperature-sensing optical fiber has a monitoring range of 60km, a storage environment temperature of -10℃ to 50℃, and a sampling accuracy of 0.5m.

[0035] Secondly, the present invention provides a supercritical CO2 pipeline leakage detection device based on distributed optical fiber, which uses the aforementioned supercritical CO2 pipeline leakage detection method based on distributed optical fiber; the device includes:

[0036] The fiber optic deployment unit is used to uniformly lay three temperature-sensing optical fibers around the supercritical CO2 pipeline, with each temperature-sensing optical fiber oriented along the pipeline.

[0037] The Raman scattering unit is used to emit laser pulse signals into each temperature-sensing fiber through a laser source. During the transmission of the laser pulse signals, reflected light sensing signals in the form of backscattering Raman are generated.

[0038] The temperature acquisition unit at the detection point is used to acquire the temperature signal of each detection point along the supercritical CO2 pipeline based on the reflected light sensing signal and through the fiber optic temperature detection host.

[0039] The leakage detection unit is used to comprehensively determine whether a supercritical CO2 pipeline is leaking based on the temperature signals from various detection points, including identifying abnormal temperature signals and determining the leakage point of the supercritical CO2 pipeline.

[0040] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0041] 1. This invention relates to a method and apparatus for detecting leaks in supercritical CO2 pipelines based on distributed optical fibers. A laser signal emitted from a laser source enters the optical fiber, generating a backscattered Raman signal. The detection terminal then collects temperature pulse signals at various detection points. A data analysis module analyzes these temperature pulse signals to obtain the temperature values ​​at the detection points. By comparing these values ​​with the temperature range under normal pipeline operation, an abnormality is determined, leading to a comprehensive assessment of whether a leak has occurred in the supercritical CO2 pipeline. This ensures the safety of the supercritical CO2 pipeline during use, prevents further escalation of the fault, minimizes the harm caused by pipeline leaks, and guarantees the safe operation of the supercritical CO2 pipeline. This invention can effectively detect leaks in supercritical CO2 pipelines over a long period and pinpoint the location of any leaks.

[0042] 2. This invention relates to a method and device for detecting leaks in supercritical CO2 pipelines based on distributed optical fibers. In this invention, three optical fibers are laid: one directly below the pipeline, one to the upper left of the pipeline, and one to the upper right of the pipeline. The three optical fibers are 15cm away from the pipeline. Temperature signals are collected through the three optical fibers to prevent temperature changes caused by CO2 pipeline leaks from going undetected by the optical fibers. This allows for comprehensive detection of the CO2 pipeline with high accuracy.

[0043] 3. This invention relates to a method and apparatus for detecting leaks in supercritical CO2 pipelines based on distributed optical fibers. In this invention, the leak is detected at the detection terminal (i.e.,...) Figure 5The temperature measurement host in the system displays the stored temperature pulse signals of each detection point under normal conditions on the monitor in real time. Simultaneously, the fiber optic detection system sends the temperature pulse signals of each detection point in real time, feeding back both the pre-stored pulse signals and the real-time pulse signals to the detection terminal. This data is then processed by the terminal host (i.e.,...). Figure 5 The signal analysis module in the background monitoring host judges the real-time temperature status of the supercritical CO2 pipeline, compares it with the normal temperature threshold, and judges whether the CO2 pipeline has leaked, thereby ensuring the safety of the supercritical CO2 pipeline and the timeliness of maintenance, and reducing the degree of harm to the surrounding environment after an accident. Attached Figure Description

[0044] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and form part of this application, do not constitute a limitation thereof. In the drawings:

[0045] Figure 1 This is a flowchart of the supercritical CO2 pipeline leakage detection method based on distributed optical fiber according to the present invention;

[0046] Figure 2 This is a diagram showing the distribution of the temperature-sensing optical fiber in this invention.

[0047] Figure 3 This is a schematic diagram illustrating the principle of supercritical CO2 pipeline leakage detection according to the present invention.

[0048] Figure 4 This is a structural block diagram of the supercritical CO2 pipeline leakage detection device based on distributed optical fiber according to the present invention.

[0049] Figure 5 This is a structural diagram of the supercritical CO2 pipeline leakage detection system of the present invention. Detailed Implementation

[0050] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of this invention are only for explaining this invention and are not intended to limit this invention.

[0051] Example 1

[0052] like Figure 1 As shown, this invention relates to a method for detecting leaks in supercritical CO2 pipelines based on distributed optical fibers. The method includes:

[0053] Step 1: Lay three temperature-sensing optical fibers around the supercritical CO2 pipeline, with each fiber oriented along the pipeline's direction; the fiber optic fiber layout diagram is shown below. Figure 2 As shown.

[0054] This is because when using a single temperature-sensing optical fiber to detect CO2 pipelines, if the distance between the leak and the fiber is large, and the leaked CO2 gas will flow upwards due to gravity, by the time the temperature change at the leak affects the fiber, the impact of the leak has already spread. To avoid this situation, and to ensure the fiber can detect the upward-flowing low-temperature CO2 gas, this invention lays one optical fiber directly below, to the upper left, and to the upper right of the supercritical CO2 pipeline along its direction. Each fiber is equidistant from the supercritical CO2 pipeline, at a distance of 15 cm. These three fibers allow for comprehensive monitoring of the pipeline's operating status.

[0055] Step 2: A laser pulse signal is emitted into each temperature-sensing fiber through a laser source. During the transmission process, the laser pulse signal excites photons and light molecules in the temperature-sensing fiber, causing inelastic collisions and generating a reflected light sensing signal in the form of backscattering Raman scattering. Based on the reflected light sensing signal, the temperature signal at each detection point along the supercritical CO2 pipeline is obtained by the fiber optic temperature detection host to sense abnormal signals caused by temperature changes during the transmission process.

[0056] Step 3: Based on the temperature signals from each detection point, comprehensively determine whether a leak has occurred in the supercritical CO2 pipeline, including identifying abnormal temperature signals and determining the leak point in the supercritical CO2 pipeline.

[0057] Step 3 involves identifying abnormal temperature signals, including:

[0058] Based on the temperature signals from each detection point, the temperature signals from each detection point are compared with the preset temperature signals of each detection point stored in the fiber optic temperature detection host. If there is a difference, it is an abnormal temperature signal; otherwise, it is a normal temperature signal.

[0059] The fiber optic temperature detection host stores the temperature pulse signal S at each detection point. t1 The pulse signal S at each detection point of the optical fiber is acquired in real time. t2 t1 and t2 represent the time of data collection, and S t1 With S t2 The data is processed and compared using the data analysis module.

[0060] In step 3, the leak point in the supercritical CO2 pipeline is determined. The ambient temperature at the leak point differs significantly from the normal ambient temperature. This temperature difference can be used to implement fault alarm and fault location functions, including:

[0061] The distributed temperature-sensing optical fiber is divided into segments at fixed intervals (e.g., 1.5m) to obtain several segments, and each segment serves as a detection point.

[0062] The leak point in the supercritical CO2 pipeline is determined based on the absolute value of the temperature difference between adjacent detection points and a preset threshold; the determination criteria are as follows: ;in, The temperature values ​​are those of two adjacent detection points. This is a preset threshold value;

[0063] Preset setting threshold ,in, Temperature compensation is used to avoid the impact on measurement accuracy; it can be set to 1℃. This is to avoid the influence of external temperature changes along the axial direction of the pipeline, and the temperature compensation can be taken as 1~3℃. This is to compensate for the temperature difference caused by the uneven distribution of its own insulation layer. This part can be moderately compensated through long-term monitoring. After compensation, it can be taken as 1~2℃. This is the reliability margin temperature, which can be taken as 1~2℃.

[0064] (1) If the absolute value of the temperature difference between all adjacent detection points is All are less than the preset setting threshold. ,Right now , constant, In sequence, that is , This can eliminate the influence of abnormal points, determine that all detection points are normal, and that there are no leaks.

[0065] (2) If the absolute value of the temperature difference between adjacent detection points Greater than the preset setting threshold ,Right now If the temperature difference around the i-th detection point is not abnormal, then it is determined that there is a leak point in the segment of the detection point.

[0066] Specifically, the absolute value of the temperature difference between adjacent detection points. = , , These are the temperature values ​​of two adjacent detection points.

[0067] Step 3, determining the leak point in the supercritical CO2 pipeline, also includes:

[0068] Based on the temperature difference between the detection point and surrounding detection points, the distance between the leak point and the detection point is determined, thus obtaining the location of the leak point.

[0069] The distance between the leak point i and the first detection point is L = (i-1) × fixed distance, for example, the fixed distance is 1.5m.

[0070] Specifically, the temperature-sensing optical fiber has a monitoring range of 60km, a storage environment temperature of -10℃ to 50℃, and a sampling accuracy of 0.5m.

[0071] As a further step, the comprehensive assessment of whether a supercritical CO2 pipeline has leaked also includes:

[0072] V1: The real-time reflected light sensing signal is processed by the signal analysis module to obtain the corresponding temperature data;

[0073] V2: Performs data-level fusion of multi-source heterogeneous data from supercritical CO2 pipelines and matches them using data association rules; the multi-source heterogeneous data includes real-time monitoring data, historical monitoring data, transmission medium data, and environmental data, etc.

[0074] V3: Real-time monitoring of temperature data from supercritical CO2 pipelines includes anomaly detection and removal, as well as steady-state screening.

[0075] The normal threshold temperature T around the CO2 pipeline is denoted as T. rang =[T min T max The temperature of supercritical CO2 inside the pipe is T. c T min >T c ; denoted as the real-time temperature value T obtained at the i-th detection point of the distributed optical fiber. i , ;

[0076] When T i <T c or T i >T max If the temperature data is abnormal, it will be discarded.

[0077] The principle of CO2 pipeline leakage detection in this invention is as follows: Figure 3As shown in the diagram, three temperature-sensing optical fibers are uniformly laid around a supercritical CO2 pipeline, with each fiber oriented along the pipeline's direction. A laser pulse signal is emitted into each fiber optic cable via a laser source. During transmission, the laser pulse signal generates a reflected light sensing signal in the form of backscattered Raman scattering. Based on this reflected light sensing signal, the fiber optic temperature detection host acquires the temperature signals at various detection points along the supercritical CO2 pipeline using the fiber optic cables. If a leak occurs in the CO2 pipeline during this detection process, the supercritical CO2 inside the pipeline will transform into gaseous CO2. Due to the pressure difference between the inside and outside of the pipeline, the leaking area will rapidly eject low-temperature CO2 gas, forming a gas column. During this process, the low-temperature CO2 gas will be affected by the surrounding environment and rapidly decrease in temperature. The corresponding fiber optic cable will sense the temperature change, resulting in backscattered Raman light interference. The fiber optic temperature detection host receives the interference result of the returned Raman scattered light and determines whether a leak has occurred at that location by comparing it with the normal signals already recorded in the host.

[0078] Specifically, since three temperature-sensing optical fibers are evenly laid around the supercritical CO2 pipeline, if the CO2 pipeline leaks, the ambient temperature at the leak point will change due to the high-pressure, low-temperature gas ejection. This will cause a change in the refractive index of the temperature-sensing optical fiber at the corresponding location, resulting in backscattered Raman light interference. The temperature value at the detection point is obtained through the data analysis module of the optical fiber temperature detection host. The optical fiber temperature detection host displays the temperature value corresponding to the monitoring point and plots the time-domain waveform curve of the temperature data. By extracting features from the time-domain waveform curve of the temperature data and removing interference, the operating status of the pipeline can be determined through the feature points on the curve.

[0079] Among them, the fiber optic temperature detection host adopts data and mechanism fusion driving technology to extract features from the time-domain waveform of temperature data. By comparing sample data in the time domain, it finds the commonalities of temperature data, thereby obtaining the feature values ​​of key points on the temperature curve to intuitively help determine the current state of supercritical CO2.

[0080] Among them, historical monitoring databases and real-time monitoring databases of three distributed temperature measurement optical fibers were established respectively, and their statistical features were extracted. The features include maximum value, minimum value, extreme value, mean value, kurtosis, etc. Feature extraction is beneficial to remove interference and improve the efficiency of model data use.

[0081] Among them, the temperature values ​​of the "extreme points" on the ambient temperature curve around the CO2 pipeline are recorded in the database. If the temperature value of the "extreme point" collected in a certain time exceeds the threshold value of the data in the database, it can be determined that the detection point is in a fault state.

[0082] In summary, the laser signal emitted by the laser source enters the optical fiber, generating a backscattered Raman signal. The detection terminal then collects the temperature pulse signals at each detection point. The data analysis module analyzes the collected temperature pulse signals to obtain the temperature value at each detection point. By comparing the temperature with the normal operating temperature range of the pipeline, it is determined whether there is any abnormality. This ensures the safety of the supercritical CO2 pipeline during use, prevents the escalation of the fault, minimizes the harm caused by pipeline leakage, and guarantees the safe operation of the supercritical CO2 pipeline.

[0083] Example 2

[0084] like Figure 4 As shown, the difference between this embodiment and Embodiment 1 is that this embodiment provides a supercritical CO2 pipeline leakage detection device based on distributed optical fiber. This device uses the supercritical CO2 pipeline leakage detection method based on distributed optical fiber from Embodiment 1. The device includes:

[0085] The fiber optic deployment unit is used to uniformly lay three temperature-sensing optical fibers around the supercritical CO2 pipeline, with each temperature-sensing optical fiber oriented along the pipeline.

[0086] The Raman scattering unit is used to emit laser pulse signals into each temperature-sensing fiber through a laser source. During the transmission of the laser pulse signals, reflected light sensing signals in the form of backscattering Raman are generated.

[0087] The temperature acquisition unit at the detection point is used to acquire the temperature signal of each detection point along the supercritical CO2 pipeline based on the reflected light sensing signal and through the fiber optic temperature detection host.

[0088] The leakage detection unit is used to comprehensively determine whether a supercritical CO2 pipeline is leaking based on the temperature signals from various detection points, including identifying abnormal temperature signals and determining the leakage point of the supercritical CO2 pipeline.

[0089] The execution process of each unit can be carried out according to the procedure of the supercritical CO2 pipeline leakage detection method based on distributed optical fiber in Example 1, and will not be described in detail in this example.

[0090] A supercritical CO2 pipeline leak detection system based on temperature-sensing optical fiber, an optical fiber temperature detection host, and a back-end monitoring host, such as... Figure 5 As shown.

[0091] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0092] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0093] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0094] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0095] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for detecting leaks in supercritical CO2 pipelines based on distributed optical fibers, characterized in that, The method includes: Three temperature-sensing optical fibers are evenly laid around the supercritical CO2 pipeline, and the direction of each temperature-sensing optical fiber is along the pipeline. A laser pulse signal is emitted into each temperature-sensing fiber by a laser source. During the transmission process, the laser pulse signal generates a reflected light sensing signal in the form of backscattering Raman scattering. Based on reflected light sensing signals, the temperature signals of each detection point along the supercritical CO2 pipeline are obtained by the fiber optic temperature detection host. Based on the temperature signals from each detection point, a comprehensive judgment is made as to whether a leak has occurred in the supercritical CO2 pipeline, including judging abnormal temperature signals and determining the leak point in the supercritical CO2 pipeline. Determining the leak point in a supercritical CO2 pipeline includes: The distributed temperature-sensing optical fiber is divided into segments at fixed intervals to obtain several segments, and each segment serves as a detection point. The leak point of the supercritical CO2 pipeline is determined by comparing the absolute value of the temperature difference between adjacent detection points with the preset set threshold. If the absolute value of the temperature difference between all adjacent detection points is less than the preset threshold, then it is determined that all detection points are normal and there is no leak. If the absolute value of the temperature difference between adjacent detection points is greater than the preset threshold, and the temperature difference around the i-th detection point is not abnormal, then it is determined that there is a leak point in the segment of the detection point. The absolute value of the temperature difference between adjacent detection points = , , The temperature values ​​of two adjacent detection points; The preset setting threshold ,in, This is to avoid the impact of measurement accuracy on temperature compensation; It is temperature compensation to avoid the influence of external temperature changes along the axial direction of the pipeline. This is to compensate for the temperature difference caused by the uneven distribution of its own insulation layer. It is a reliability margin temperature; Determining the leak point in a supercritical CO2 pipeline also includes: Based on the temperature difference between the detection point and surrounding detection points, the distance between the leak point and the detection point is determined, thus obtaining the location of the leak point. The distance between the leak point i and the first detection point is L = (i-1) × fixed distance.

2. The method for detecting leakage in supercritical CO2 pipelines based on distributed optical fibers according to claim 1, characterized in that, Three temperature-sensing optical fibers are evenly laid around the supercritical CO2 pipeline, with each fiber oriented along the pipeline's direction. Specifically: One optical fiber is laid directly below, to the upper left and to the upper right of the supercritical CO2 pipeline along the pipeline's direction.

3. The method for detecting leaks in supercritical CO2 pipelines based on distributed optical fibers according to claim 2, characterized in that, The distance between each temperature-sensing optical fiber and the supercritical CO2 pipeline is equal and 15cm.

4. The method for detecting leakage in supercritical CO2 pipelines based on distributed optical fibers according to claim 1, characterized in that, Determining abnormal temperature signals includes: Based on the temperature signals from each detection point, the temperature signals from each detection point are compared with the preset temperature signals of each detection point stored in the fiber optic temperature detection host. If there is a difference, it is an abnormal temperature signal; otherwise, it is a normal temperature signal.

5. The method for detecting leakage in supercritical CO2 pipelines based on distributed optical fibers according to claim 1, characterized in that, A comprehensive assessment of whether a supercritical CO2 pipeline is leaking also includes: V1: The real-time reflected light sensing signal is processed by the signal analysis module to obtain the corresponding temperature data; V2: Multi-source heterogeneous data from supercritical CO2 pipelines are fused at the data level and matched using data association rules; the multi-source heterogeneous data includes real-time monitoring data, historical monitoring data, transmission medium data, and environmental data; V3: Real-time monitoring of temperature data from supercritical CO2 pipelines includes anomaly detection and removal, as well as steady-state screening. The normal threshold temperature T around the CO2 pipeline is denoted as T. rang =[T min T max The temperature of supercritical CO2 inside the pipe is T. c T min >T c ; denoted as the real-time temperature value T obtained at the i-th detection point of the distributed optical fiber. i , ; When T i <T c or T i >T max If the temperature data is abnormal, it will be discarded.

6. The method for detecting leakage in supercritical CO2 pipelines based on distributed optical fibers according to claim 1, characterized in that, The temperature-sensing optical fiber has a monitoring range of 60km, a storage environment temperature of -10℃ to 50℃, and a sampling accuracy of 0.5m.

7. A supercritical CO2 pipeline leakage detection device based on distributed optical fiber, characterized in that, The device uses the supercritical CO2 pipeline leakage detection method based on distributed optical fiber as described in any one of claims 1 to 6; the device comprises: The fiber optic deployment unit is used to uniformly lay three temperature-sensing optical fibers around the supercritical CO2 pipeline, with each temperature-sensing optical fiber oriented along the pipeline. The Raman scattering unit is used to emit laser pulse signals into each temperature-sensing fiber through a laser source. During the transmission of the laser pulse signals, reflected light sensing signals in the form of backscattering Raman are generated. The temperature acquisition unit at the detection point is used to acquire the temperature signal of each detection point along the supercritical CO2 pipeline based on the reflected light sensing signal and through the fiber optic temperature detection host. The leakage detection unit is used to comprehensively determine whether a supercritical CO2 pipeline is leaking based on the temperature signals from various detection points, including identifying abnormal temperature signals and determining the leakage point of the supercritical CO2 pipeline.

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