Supercritical CO2 pipeline leakage detection method and device based on distributed optical fibers

Abstract

The invention discloses a supercritical CO2 pipeline leakage detection method and device based on distributed optical fibers, and the method comprises the steps: uniformly laying three temperature-sensitive optical fibers at the periphery of a supercritical CO2 pipeline, and enabling each temperature-sensitive optical fiber to move along the pipeline; laser pulse signals are emitted into the temperature sensing optical fibers through the laser source, and reflected light sensing signals in a backward Raman scattering form are generated in the transmission process of the laser pulse signals; based on the reflected light sensing signal, acquiring a temperature signal of the temperature sensing optical fiber along each detection point of the supercritical CO2 pipeline through an optical fiber temperature detection host; and comprehensively judging whether the supercritical CO2 pipeline leaks or not according to the temperature signal of each detection point, including judging an abnormal temperature signal and judging a leakage point of the supercritical CO2 pipeline. The supercritical CO2 pipeline leakage can be effectively detected for a long time, and the detection precision is high.

Description

Technical Field

[0001] The present invention relates to the technical field of supercritical CO 2 pipeline detection, and particularly to a method and device for detecting leakage of supercritical CO 2 pipelines based on distributed optical fibers. Background Technique

[0002] China has issued a series of documents to encourage the development of CCUS technology and included CCUS technology in the scope of support for a number of major projects, pointing the way for the development of CCUS technology. At present, the main ways to transport CO 2 are transportation and pipeline transportation. Transportation is to compress CO 2 into a solid or liquid state, load it into a container and then transport it. Pipeline transportation is to use a CO 2 pipeline for transportation. For short-term CO 2 transportation, transportation is more economical, while for long-term transportation, pipelines are more efficient. Using pipelines to transport CO 2 is an important part of realizing CCUS, and the role played by supercritical CO 2 pipelines is becoming increasingly important. Pressurizing CO 2 to the supercritical state is the most economical transportation method. In this state, CO 2 not only has a high density similar to that of a liquid, but also has a high diffusivity and low viscosity similar to that of a gas, and can be transported in large quantities and quickly. For supercritical CO 2 pipelines, even if they are buried underground during operation, they will still be affected by factors such as meteorological disasters, geological movements, and human activities. However, once a CO 2 pipeline leaks, it will directly affect the environment near the leak: the leakage of high-pressure CO 2 gas flow will generate a huge impact force, damaging the surrounding environment; the temperature at the leakage point will drop sharply, harming the organisms in the surrounding area and easily causing secondary accidents. In addition, since the gas density of CO 2 is greater than that of air, the CO 2 concentration in the surrounding area will rise rapidly after the pipeline leaks. If it accumulates for a long time in relatively low-lying areas, it will cause a certain degree of asphyxiation hazard to the animals and plants in this area. Therefore, mastering the operating state of supercritical CO 2 pipelines can not only effectively prevent CO 2 pipelines from being damaged externally, but also timely detect the location of pipeline failures and quickly carry out repairs to ensure the safe operation of supercritical CO 2 pipelines.

[0003] In the actual operation of supercritical CO 2 pipelines, traditional CO 2The method for the pipeline operation status is to use drones to conduct inspections within a certain area. The commonly used hardware-based leakage detection methods mainly include the negative pressure wave method, the infrasound method, etc.; Yuan Wenqiang, Lang Xianming, Cao Jiangtao, etc. Research progress of pipeline leakage detection technology based on acoustic wave method [J]. Oil & Gas Storage and Transportation, 2023, 42(02): 141-151. Using the acoustic wave method to detect the pipeline leakage status, since the transmission medium of the acoustic wave has a great influence on the propagation of the acoustic wave, when the pipeline leakage volume is small or the fluid has a high elastic coefficient, viscosity or density, it cannot be detected due to insufficient sensitivity. Gao Lin, Cao Jianguo. Review of pipeline leakage detection methods [J]. Modern Manufacturing Engineering, 2022, No. 497(02): 154-162 elaborated on the pipeline leakage detection methods, emphasizing the research progress of methods such as leakage signal recognition and positioning processing methods, but did not target the research on supercritical CO 2 pipeline detection.

[0004] To sum up, the existing detection methods have many drawbacks, lacking efficient and economical detection means, and unable to detect supercritical CO 2 pipeline leakage effectively for a long time. Summary of the Invention

[0005] The purpose of the present invention is to provide a supercritical CO 2 pipeline leakage detection method and device based on distributed optical fiber. The distributed optical fiber sensor is laid at specific positions around the supercritical CO 2 pipeline to achieve all-round detection of the pipeline operation status, and solve various problems such as high labor cost, long time cycle, and insufficient sensitivity during the traditional inspection of supercritical CO 2 pipeline. The present invention can effectively detect supercritical CO 2 pipeline leakage for a long time and has high detection accuracy.

[0006] The present invention is realized through the following technical solutions:

[0007] In the first aspect, the present invention provides a supercritical CO 2 pipeline leakage detection method based on distributed optical fiber, and the method includes:

[0008] Lay 3 temperature-sensitive optical fibers around the supercritical CO 2 pipeline, and the direction of each temperature-sensitive optical fiber is along the pipeline direction;

[0009] Emit laser pulse signals into each temperature-sensitive optical fiber through a laser source. During the transmission process, the laser pulse signals have a certain excitation effect on the photons and light molecules in the temperature-sensitive optical fiber, resulting in inelastic collisions and generating reflected light induction signals in the form of backward Raman scattering;

[0010] Based on the reflected light induction signal, the fiber optic temperature detection host obtains the temperature signals of each detection point of the temperature sensing optical fiber along the supercritical CO 2 pipeline;

[0011] According to the temperature signals of each detection point, comprehensively judge whether the supercritical CO 2 pipeline leaks, including judging abnormal temperature signals and judging the leakage points of the supercritical CO 2 pipeline.

[0012] In the above technical solution, if the CO 2 pipeline leaks during the detection process, the leaking part will eject low-temperature CO 2 gas to the outside, the temperature of the surrounding environment will be affected and drop rapidly, the optical fiber at the corresponding position will sense the temperature change, and at the same time, it will cause the result of the interference of the backward Raman scattered light; the fiber optic temperature detection host receives the interference result of the returned Raman scattered light, and judges whether there is a leak at this position by comparing with the normal signals already stored in the host.

[0013] Further, 3 temperature sensing optical fibers are evenly laid around the supercritical CO 2 pipeline, and the direction of each temperature sensing optical fiber is along the pipeline direction, specifically:

[0014] One optical fiber is laid along the pipeline direction directly below, in the upper left and upper right of the supercritical CO 2 pipeline respectively.

[0015] Further, the distance between each temperature sensing optical fiber and the supercritical CO 2 pipeline is equal, and it is 15 cm.

[0016] Further, judging abnormal temperature signals includes:

[0017] According to the temperature signals of each detection point, compare the temperature signals of each detection point 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] Further, judging the leakage point of the supercritical CO 2 pipeline includes:

[0019] The distributed temperature sensing optical fiber is segmented at fixed intervals (such as 1.5 m) to obtain several segments, and each segment is used as a detection point;

[0020] According to the absolute value of the temperature difference between adjacent detection points and the preset setting threshold, judge the leakage point of the supercritical CO 2 pipeline;

[0021] If the absolute value of the temperature difference ΔT between all adjacent detection points B is greater than the preset setting threshold T set , that is, ΔT B > T set , then it is determined that all detection points are normal and there is no leakage point;

[0022] If the absolute value of the temperature difference ΔT between adjacent detection points B is greater than the preset setting threshold T set , that is, ΔT B > T set , and there is no abnormality in the temperature difference around the i-th detection point, then it is determined that there is a leakage point in the segment of this detection point.

[0023] Furthermore, the absolute value of the temperature difference ΔT between adjacent detection points B = |T i - T i+1 |, where T i , T i+1 are the temperature values of two adjacent detection points;

[0024] The preset setting threshold T set = T m + T o + T g + T y , where T m is the temperature compensation to avoid the influence caused by the measurement accuracy and can be set to 1°C; T o is the temperature compensation to avoid the influence of the external temperature change in the axial direction of the pipeline and can take a value of 1 - 3°C; T g is the temperature compensation to avoid the influence of the inherent temperature difference caused by the uneven distribution of its own insulation layer, and this part can be moderately compensated through long-term monitoring, and can take a value of 1 - 2°C after compensation; T y is the reliable margin temperature and can take a value of 1 - 2°C.

[0025] Furthermore, to determine the leakage point of the supercritical CO 2 pipeline, it also includes:

[0026] According to the temperature difference between the detection point and the surrounding detection points, locate the distance between the leakage point and the detection point to obtain the position of the leakage point;

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

[0028] Furthermore, to comprehensively determine whether the supercritical CO 2 pipeline leaks, it also includes:

[0029] V1: The real-time reflected light induction signal passes through the signal analysis module to obtain the corresponding temperature data;

[0030] V2: Perform data-level fusion on the multi-source heterogeneous data of the supercritical CO 2 pipeline, and match it through data association rules; the multi-source heterogeneous data includes real-time monitoring data, historical monitoring data, transmission medium data, environmental data, etc.;

[0031] V3: Detect and eliminate abnormal points and perform steady-state screening on the temperature data of the supercritical CO 2 pipeline in real-time monitoring;

[0032] Denote the normal threshold T 2 of the ambient temperature around the CO rang pipeline as = [T min , T max , and the temperature of the supercritical CO 2 in the pipeline is T c , where T min > T c ; Denote the real-time temperature value T i obtained at the i-th detection point of the distributed optical fiber, i = 1, 2, 3, 4..., n;

[0033] When T i < T c or T i > T max , then this temperature data is abnormal data and is directly eliminated.

[0034] Further, the monitoring range of the temperature-sensitive optical fiber is 60 km, the storage ambient temperature is -10°C - 50°C, and the sampling accuracy is 0.5 m.

[0035] In the second aspect, the present invention further provides a supercritical CO2 pipeline leakage detection device based on distributed optical fiber, and this device uses the above-mentioned supercritical CO 2 pipeline leakage detection method; this device includes:

[0036] An optical fiber arrangement unit for evenly laying 3 temperature-sensitive optical fibers around the supercritical CO 2 pipeline, and the direction of each temperature-sensitive optical fiber is along the pipeline direction;

[0037] A Raman scattering unit for emitting laser pulse signals into each temperature-sensitive optical fiber through a laser source, and the laser pulse signals generate reflected light induction signals in the form of backward Raman scattering during transmission;

[0038] A detection point temperature acquisition unit for obtaining the temperature of the temperature-sensitive optical fiber along the supercritical CO 2The temperature signals at each detection point of the pipeline;

[0039] A leakage judgment unit, which is used to comprehensively judge whether the supercritical CO 2 pipeline leaks according to the temperature signals at each detection point, including judging abnormal temperature signals and judging the leakage points of the supercritical CO 2 pipeline.

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

[0041] 1. The supercritical CO 2 pipeline leakage detection method and device based on distributed optical fiber. The laser signal emitted by the laser light source enters the optical fiber and generates a backward Raman scattering signal. The detection terminal will collect the temperature pulse signals at each detection point. The data analysis module analyzes the collected temperature pulse signals to obtain the temperature values at the detection points. By comparing the temperature range under normal pipeline operation conditions, it is judged whether there is an abnormal situation, and it is comprehensively judged whether the supercritical CO 2 pipeline leaks, so as to ensure the safety of the supercritical CO 2 pipeline during use, avoid the further expansion of faults, minimize the harm caused by pipeline leakage, and ensure the safe operation of the supercritical CO 2 pipeline. The invention can effectively detect whether the supercritical CO 2 pipeline leaks and the leakage location for a long time.

[0042] 2. The supercritical CO 2 pipeline leakage detection method and device based on distributed optical fiber. In the present invention, 3 optical fibers are laid. One is laid directly below the pipeline, one is laid in the upper left of the pipeline, and one is laid in the upper right of the pipeline. The 3 optical fibers are 15 cm away from the pipeline. The temperature signals are collected through the 3 optical fibers to prevent the temperature change caused by the leakage of the CO 2 pipeline from not being detected by the optical fiber; the CO 2 pipeline is detected comprehensively, and the detection accuracy is high.

[0043] 3. The supercritical CO 2 pipeline leakage detection method and device based on distributed optical fiber. In the present invention, by displaying on the monitor of the detection terminal (i.e., the temperature measurement host in Figure 5 ) the temperature pulse signals of each detection point of the optical fiber stored under normal conditions in real time, and at the same time the optical fiber detection system sends the temperature pulse signals of each detection point in real time, and feeds the pre-stored pulse signals and the real-time pulse signals back to the detection terminal together. The signal analysis module in the terminal host (i.e., the background monitoring host in Figure 5 ) judges the supercritical CO 2The real-time temperature status of the pipeline is compared with the normal temperature threshold to judge whether there is a leakage in the CO 2 pipeline, so as to ensure the safety of the supercritical CO 2 pipeline and the timeliness of maintenance, and reduce the harm to the surrounding environment after an accident occurs. Description of the Drawings

[0044] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, form a part of this application, and do not constitute a limitation to the embodiments of the present invention. In the drawings:

[0045] Figure 1 is the flowchart of the supercritical CO 2 pipeline leakage detection method based on distributed optical fiber of the present invention;

[0046] Figure 2 is the distribution diagram of the temperature-sensitive optical fiber laying of the present invention;

[0047] Figure 3 is the schematic diagram of the supercritical CO 2 pipeline leakage detection of the present invention;

[0048] Figure 4 is the structural block diagram of the supercritical CO 2 pipeline leakage detection device based on distributed optical fiber of the present invention;

[0049] Figure 5 is the structural diagram of the supercritical CO 2 pipeline leakage detection system of the present invention. Detailed Embodiments

[0050] To make the purpose, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with the embodiments and the drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and do not constitute a limitation to the present invention.

[0051] Embodiment 1

[0052] As Figure 1 shown, the supercritical CO 2 pipeline leakage detection method based on distributed optical fiber of the present invention includes:

[0053] Step 1, lay 3 temperature-sensitive optical fibers around the supercritical CO 2 pipeline, and the direction of each temperature-sensitive optical fiber is along the pipeline direction; the distribution diagram of the temperature-sensitive optical fiber laying is as Figure 2 shown.

[0054] This is considered because when using a single temperature-sensitive optical fiber to detect the CO 2 pipeline, if the CO 2The distance between the pipeline leakage point and the temperature-sensitive optical fiber is relatively far. At the same time, the leaked CO 2 gas will flow upward along the pipeline under the influence of gravity. By the time the temperature change at the pipeline leakage point affects the temperature-sensitive optical fiber, the influence range caused by the pipeline leakage has expanded. To avoid the above situation and to enable the temperature-sensitive optical fiber to detect the upward-flowing low-temperature CO 2 gas, in the present invention, one optical fiber is laid along the pipeline direction respectively directly below, in the upper left and upper right of the supercritical CO 2 pipeline. The distance between each temperature-sensitive optical fiber and the supercritical CO 2 pipeline is equal, and is 15 cm. Three temperature-sensitive optical fibers are used to comprehensively detect the operating state of the pipeline.

[0055] Step 2: A laser pulse signal is emitted into each temperature-sensitive optical fiber through a laser source. During the transmission process of the laser pulse signal, it has a certain excitation effect on the photons and light molecules in the temperature-sensitive optical fiber, resulting in inelastic collisions and generating a reflected light induction signal in the form of backward Raman scattering; based on the reflected light induction signal, the temperature signal of each detection point of the temperature-sensitive optical fiber along the supercritical CO 2 pipeline is obtained through a fiber optic temperature detection host to sense the abnormal signal caused by the temperature change during the transmission process;

[0056] Step 3: According to the temperature signals of each detection point, comprehensively judge whether the supercritical CO 2 pipeline leaks, including judging the abnormal temperature signal and judging the leakage point of the supercritical CO 2 pipeline.

[0057] In Step 3, judging the abnormal temperature signal includes:

[0058] According to the temperature signals of each detection point, compare the temperature signals of each detection point with the preset temperature signals of each detection point pre-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 temperature pulse signal S t1 of each detection point pre-stored in the fiber optic temperature detection host, and the pulse signal S t2 of each detection point of the optical fiber is collected in real time. t1 and t2 represent the collection moments, and S t1 and S t2 are processed and compared through a data analysis module.

[0060] In Step 3, judging the leakage point of the supercritical CO 2 pipeline, the ambient temperature at the leakage point is quite different from the normal ambient temperature. Using this temperature difference, the functions of fault warning and fault location can be realized, including:

[0061] The distributed temperature-sensing optical fiber is segmented at fixed intervals (such as 1.5 m) to obtain a number of segments, and each segment serves as a detection point;

[0062] According to the absolute value of the temperature difference between adjacent detection points and a preset setting threshold, determine the leakage point of the supercritical CO 2 pipeline; the judgment basis is: ΔT B =|T 1 -T 2 |>T set ; where T 1 and T 2 are the temperature values of two adjacent detection points, and T set is the preset setting threshold;

[0063] The preset setting threshold T set =T m +T o +T g +T y ; where T m is the temperature compensation to avoid the influence caused by the measurement accuracy and can be set to 1 °C; T o is the temperature compensation to avoid the influence of the external temperature change in the axial direction of the pipeline and can be taken as 1 - 3 °C; T g is the temperature compensation to avoid the influence of the inherent temperature difference caused by the uneven distribution of its own thermal insulation layer. This part can be moderately compensated through long-term monitoring and can be taken as 1 - 2 °C after compensation; T y is the reliable margin temperature and can be taken as 1 - 2 °C.

[0064] (1) If the absolute value of the temperature difference ΔT B between all adjacent detection points is greater than the preset setting threshold T set , that is, ΔT B >T set , T 1 remains unchanged, and T 2 is shifted sequentially, that is, T 3 , T 4 , T i …T n , i = 1, 2, 3, 4…, n, then the influence of abnormal points can be eliminated, and it is judged that each detection point is normal and there is no leakage point;

[0065] (2) If the absolute value of the temperature difference ΔT B between adjacent detection points is greater than the preset setting threshold T set , that is, ΔT B >T set , and there is no abnormality in the temperature difference around the i-th detection point, then it is judged that there is a leakage point in the segment of this detection point.

[0066] Specifically, the absolute value of the difference in temperature values between adjacent detection points, ΔT B = |T i - T i+1 |, where T i and T i+1 are the temperature values of two adjacent detection points.

[0067] In step 3, to determine the leakage point of the supercritical CO 2 pipeline, it further includes:

[0068] Based on the temperature difference between the detection point and the surrounding detection points, locate the distance between the leakage point and the detection point to obtain the position of the leakage point;

[0069] Among them, the distance between the leakage point i and the first detection point is L = (i - 1) × fixed distance. For example, the fixed distance is 1.5 m.

[0070] Specifically, the monitoring range of the temperature-sensing optical fiber is 60 km, the storage environment temperature is -10°C - 50°C, and the sampling accuracy is 0.5 m.

[0071] As a further implementation, to comprehensively determine whether the supercritical CO 2 pipeline has leaked, it further includes:

[0072] V1: The real-time reflected light induction signal passes through the signal analysis module to obtain the corresponding temperature data;

[0073] V2: Perform data-level fusion on the multi-source heterogeneous data of the supercritical CO 2 pipeline and match through data association rules; the multi-source heterogeneous data includes real-time monitoring data, historical monitoring data, transmission medium data, environmental data, etc.;

[0074] V3: Perform outlier detection, rejection, and steady-state screening on the temperature data of the supercritical CO 2 pipeline in real-time monitoring;

[0075] Denote the normal threshold T 2 of the ambient temperature around the CO rang transport pipeline as T min , T max , the temperature of the supercritical CO 2 inside the pipeline is T c , where T min > T c ; Denote the real-time temperature value T i obtained by the i-th detection point of the distributed optical fiber, i = 1, 2, 3, 4,..., n;

[0076] When T i < T c or T i > Tmax If so, the temperature data is abnormal data and will be directly excluded.

[0077] The CO of the present invention 2 Principle for detecting pipeline leakage, as Figure 3 shown. Three temperature sensing optical fibers are evenly laid around the supercritical CO 2 pipeline, and the direction of each temperature sensing optical fiber is along the pipeline direction; a laser pulse signal is emitted into each temperature sensing optical fiber through a laser source, and a reflected light induction signal in the form of backward Raman scattering is generated during the transmission of the laser pulse signal; based on the reflected light induction signal, the temperature signal of each detection point of the temperature sensing optical fiber along the supercritical CO 2 pipeline is obtained through a fiber optic temperature detection host; if there is a leakage in the CO 2 pipeline during the above detection process, the supercritical CO inside the pipeline 2 will turn into gaseous CO 2 , affected by the pressure difference inside and outside the pipeline, the leakage part will quickly eject low-temperature CO 2 gas to form a gas column. During this period, the temperature of the surrounding environment will be affected by the low-temperature CO 2 gas and will drop rapidly. The optical fiber at the corresponding position will sense the temperature change, and at the same time, it will cause the result of the interference of the backward Raman scattered light; the fiber optic temperature detection host receives the interference result of the returned Raman scattered light and judges whether there is a leakage at this position by comparing with the normal signal already stored in the host.

[0078] Specifically, since three temperature sensing optical fibers are evenly laid around the supercritical CO 2 pipeline, if there is a leakage in the CO 2 pipeline, affected by the ejection of high-pressure and low-temperature gas, the environmental temperature at the leakage point will change, and the refractive index of the temperature sensing optical fiber at the corresponding position will change, thus causing the result of the interference of the backward Raman scattered light. The temperature value of the detection point is obtained through the data analysis module of the fiber optic temperature detection host; the fiber optic temperature detection host displays the temperature value corresponding to the monitoring point and draws the time-domain waveform curve of the temperature data. By extracting the characteristics of the time-domain waveform curve of the temperature data and removing the interference, the operating state of the pipeline is judged through the characteristic points on the curve.

[0079] Among them, the fiber optic temperature detection host adopts a data and mechanism fusion-driven technology to extract the characteristics of the time-domain waveform of the temperature data. By comparing the sample data in the time domain, the common points of the temperature data are found, so as to obtain the characteristic values of the key points on the temperature curve to visually help judge the 2 current state of the supercritical CO

[0080] Among them, the historical monitoring database and real-time monitoring database of three distributed temperature measurement optical fibers are established respectively, and their statistical characteristics are extracted. The characteristics include maximum value, minimum value, extreme value, mean value, kurtosis, etc. Feature extraction is conducive to removing interference and improving the efficiency of model data use;

[0081] Among them, CO 2 The temperature value of the "extreme point" on the ambient temperature curve of the pipeline is recorded in the database. If the temperature value of the "extreme point" collected at a certain time exceeds the threshold value of the data in the database, it can be judged that the current detection point is in a fault state;

[0082] In summary, the laser signal emitted by the laser light source enters the optical fiber and generates a backward Raman scattering signal. The detection terminal will collect the temperature pulse signal at each detection point. The collected temperature pulse signal is analyzed by the data analysis module to obtain the temperature value at the detection point. By comparing the temperature range under normal operation of the pipeline, it is judged whether there is an abnormal situation, thereby ensuring the supercritical CO 2 The safety of the pipeline during use can avoid further expansion of the fault, minimize the harm caused by pipeline leakage, and ensure the safety of supercritical CO 2 Safe operation of pipelines.

[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, which uses the supercritical CO2 pipeline leakage detection device based on distributed optical fiber of embodiment 1. 2 Pipeline leakage detection method; the device comprises:

[0085] Fiber Optic Arrangement Unit for Supercritical CO 2 Three temperature-sensing optical fibers are evenly laid around the pipeline, and the direction of each temperature-sensing optical fiber is along the pipeline;

[0086] A Raman scattering unit is used to transmit a laser pulse signal into each temperature-sensitive optical fiber through a laser source, and the laser pulse signal generates a reflected light sensing signal in the form of backward Raman scattering during the transmission process;

[0087] The detection point temperature acquisition unit is used to obtain the temperature of the temperature sensing optical fiber along the supercritical CO through the optical fiber temperature detection host based on the reflected light sensing signal. 2 Temperature signals at each detection point on the pipeline;

[0088] The leakage judgment unit is used to comprehensively judge the supercritical CO based on the temperature signals of each detection point. 2 Whether the pipeline is leaking, including judging abnormal temperature signals and supercritical CO 2The leakage point of the pipeline.

[0089] Among them, the execution process of each unit is carried out according to the steps of the method for detecting pipeline leakage based on distributed optical fiber in Embodiment 1, and will not be elaborated one by one in this embodiment. 2 The pipeline leakage detection method process steps can be executed as such, and will not be elaborated one by one in this embodiment.

[0090] The supercritical CO pipeline leakage detection system formed by the temperature-sensitive optical fiber, the optical fiber temperature detection host and the background monitoring host is as 2 shown. Figure 5 shown.

[0091] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system, or a computer program product. Therefore, the present application can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can take the form of a computer program product implemented 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] The present application is described with reference to the flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each flow and / or block in the flowchart and / or block diagram can be implemented by computer program instructions, and the combination of the flows and / or blocks in the flowchart and / or block diagram can also be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate a device for realizing the functions specified in one Figure 1 flow or multiple flows and / or blocks Figure 1 or multiple blocks.

[0093] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer-readable memory generate a manufactured product including an instruction device, and the instruction device realizes the functions specified in one Figure 1 flow or multiple flows and / or blocks Figure 1 or multiple blocks.

[0094] These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process, and thus the instructions executed on the computer or other programmable device provide for realizing the functions in one Figure 1 flow or multiple flows and / or blocksFigure 1 Steps of functions specified in one or more boxes.

[0095] The specific embodiments described above further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. Supercritical CO based on distributed optical fiber 2 Pipeline leak detection methods, It is characterized in that The method includes: In supercritical CO 2 Three temperature-sensing optical fibers are evenly laid around the pipeline, and the direction of each temperature-sensing optical fiber is along the pipeline; A laser pulse signal is emitted into each temperature-sensitive optical fiber through a laser source, and the laser pulse signal generates a reflected light sensing signal in the form of back Raman scattering during the transmission process; Based on the reflected light sensing signal, the optical fiber temperature detection host obtains the temperature of the temperature sensing optical fiber along the supercritical CO 2 Temperature signals at each detection point of the pipeline; According to the temperature signals of each detection point, the supercritical CO 2 Whether the pipeline is leaking, including judging abnormal temperature signals and supercritical CO 2 Leakage point of the pipeline.

2. The distributed optical fiber-based supercritical CO according to claim 1 2 Pipeline leak detection methods, It is characterized in that In supercritical CO 2 Three temperature-sensing optical fibers are evenly laid around the pipeline, and the direction of each temperature-sensing optical fiber is along the pipeline. Specifically: In supercritical CO 2 An optical fiber is laid directly below, on the upper left, and on the upper right along the direction of the pipeline.

3. The distributed optical fiber-based supercritical CO according to claim 2 2 Pipeline leak detection methods, It is characterized in that Each temperature-sensitive optical fiber is connected to supercritical CO 2 The distance between the pipes is equal and is 15cm.

4. The distributed optical fiber-based supercritical CO according to claim 1 2 Pipeline leak detection methods, It is characterized in that Determine abnormal temperature signals, including: According to the temperature signal of each detection point, the temperature signal of each detection point is compared with the preset temperature signal of each detection point pre-stored in the optical fiber temperature detection host. If there is a difference, it is an abnormal temperature signal; otherwise, it is a normal temperature signal.

5. The distributed optical fiber-based supercritical CO according to claim 1 2 Pipeline leak detection methods, It is characterized in that Determine supercritical CO 2 Pipeline leak points, including: The distributed temperature-sensing optical fiber is segmented at fixed distances to obtain a number of segments, each of which serves as a detection point; The supercritical CO is judged based on the absolute value of the temperature difference between adjacent detection points and the preset setting threshold. 2 Leakage points in pipelines; If the absolute value of the temperature difference of all adjacent detection points is greater than the preset setting threshold, it is judged that all detection points are normal and there is no leakage point; If the absolute value of the temperature difference between adjacent detection points is greater than the preset setting threshold, and the temperature difference around the i-th detection point is normal, it is determined that there is a leak in the segment of the detection point.

6. The distributed optical fiber-based supercritical CO according to claim 5 2 Pipeline leak detection methods, It is characterized in that The absolute value of the temperature difference between adjacent detection points ΔT B =|T i -T i+1 |, T i 、T i+1 is the temperature value of two adjacent detection points; The preset setting threshold T set =T m +T o +T g +T y , where T m To avoid the influence of temperature compensation on measurement accuracy; T o It is a temperature compensation to avoid the influence of external temperature changes in the axial direction of the pipeline; T g This is to avoid the influence of inherent temperature difference caused by uneven distribution of its own insulation layer. Temperature compensation; T y is the reliability margin temperature.

7. The distributed optical fiber-based supercritical CO according to claim 5 2 Pipeline leak detection methods, It is characterized in that Determine supercritical CO 2 Pipeline leakage points also include: According to the temperature difference between the detection point and the surrounding detection points, the distance between the leakage point and the detection point is located to obtain the position of the leakage point; The distance between the leakage point i and the first detection point is L=(i-1)×fixed distance.

8. The distributed optical fiber-based supercritical CO according to claim 1 2 Pipeline leak detection methods, It is characterized in that Comprehensive judgment of supercritical CO 2 Whether there is leakage in the pipeline, including: V1: The real-time reflected light sensing signal passes through the signal analysis module to obtain the corresponding temperature data; V2: Supercritical CO 2 Multi-source heterogeneous data of pipelines are integrated at the data level and matched through data association rules; the multi-source heterogeneous data include real-time monitoring data, historical monitoring data, transmission medium data and environmental data; V3: Supercritical CO 2 Real-time monitoring of pipeline temperature data for abnormal point detection and elimination and steady-state screening; Recorded as transported CO 2 Normal threshold value of ambient temperature around the pipeline T rang =[T min , T max ], supercritical CO in pipeline 2 The temperature is T c , where T min >T c ; Recorded as the real-time temperature value T obtained by the i-th detection point of the distributed optical fiber i , i=1, 2, 3, 4..., n; When T i <T c or T i >T max , the temperature data is abnormal data and is directly removed.

9. The distributed optical fiber-based supercritical CO according to claim 1 2 Pipeline leak detection methods, It is characterized in that The monitoring range of the temperature-sensitive optical fiber is 60 km, the storage environment temperature is -10°C-50°C, and the sampling accuracy is 0.5m.

10. Supercritical CO based on distributed optical fiber 2 Pipeline leak detection device, It is characterized in that The device uses a distributed optical fiber-based supercritical CO as described in any one of claims 1 to 9. 2 Pipeline leakage detection method; the device comprises: Fiber Optic Arrangement Unit for Supercritical CO 2 Three temperature-sensing optical fibers are evenly laid around the pipeline, and the direction of each temperature-sensing optical fiber is along the pipeline; A Raman scattering unit is used to transmit a laser pulse signal into each temperature-sensitive optical fiber through a laser source, and the laser pulse signal generates a reflected light sensing signal in the form of backward Raman scattering during the transmission process; The detection point temperature acquisition unit is used to obtain the temperature of the temperature sensing optical fiber along the supercritical CO through the optical fiber temperature detection host based on the reflected light sensing signal. 2 Temperature signals at each detection point on the pipeline; The leakage judgment unit is used to comprehensively judge the supercritical CO based on the temperature signals of each detection point. 2 Whether the pipeline is leaking, including judging abnormal temperature signals and supercritical CO 2 Leakage point of the pipeline.

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