Array type leakage detection and prediction method for monitoring leakage of chassis of high-temperature fused salt storage tank

Abstract

An array type leakage detection and prediction method for monitoring leakage of a high-temperature fused salt storage tank chassis belongs to the technical field of instrument automation, and realizes prediction and detection of leakage of the storage tank chassis by arranging an array type temperature measurement sensor at the bottom of a storage tank, monitoring the change of a temperature field at the bottom of the storage tank in real time and assisting with a fused salt leakage model and a leakage database. The array type temperature sensors are buried in a basic heat insulation material of the fused salt storage tank, and the array type temperature sensors are arranged on the upper middle portion of the heat insulation layer according to the tank bottom welding seam and the temperature field distribution condition and are arranged in a net-shaped and non-uniform mode. The planar array type temperature sensors are respectively connected into different acquisition channels, the change trend of a temperature field of the storage tank chassis is comprehensively sensed through a multi-channel data acquisition device, and the leakage position of the molten salt storage tank chassis is predicted, found and positioned by means of a molten salt leakage model and a leakage database. According to the invention, prediction and detection of leakage of the fused salt storage tank are realized, accurate positioning is realized, and occurrence or expansion of leakage accidents of the storage tank is avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of instrument automation, and in particular relates to an array leak detection and prediction method for monitoring chassis leakage of a high-temperature molten salt storage tank. Background Art

[0002] The Liaohe Oilfield production system consumes 1.64 billion cubic meters of natural gas and 2.24 billion kilowatt-hours of electricity, equivalent to 2.4565 million tons of standard coal, and CO2 emissions of 5.28594 million tons. Natural gas consumption accounts for 88.8% of the total energy consumption, mainly used for steam injection in heavy oil thermal recovery, which is a key link in energy consumption. Under the requirements of the dual carbon goals, we explore the use of electric thermal molten salt heat storage technology to replace gas consumption and achieve "replacing gas with valley electricity / green electricity". After the implementation of this technology, it can not only reduce carbon dioxide emissions, but also make full use of valley electricity / green electricity to reduce the pressure on the power grid.

[0003] Molten salt storage tanks are key core equipment for molten salt thermal storage. If leakage is not discovered and handled in time, it will increase economic losses and bring huge safety hazards and environmental pollution risks. Leakages in the tank wall are easy to find and handle. Due to its hidden location, it is difficult to detect leakage in the tank chassis in the early stage. Generally, leakage in the molten salt storage tank chassis starts with seepage, and trace leakage is even more difficult to detect. Therefore, it is a key requirement for tank leak detection and prediction to discover or predict tank bottom leakage as soon as possible and to handle and repair it in time. Since molten salt storage tanks store high-temperature molten salt, traditional temperature sensing cables and emerging temperature measurement optical cables are difficult to meet the measurement requirements of high-temperature conditions. Therefore, this patent has developed an array leak detection and prediction method suitable for high-temperature molten salt storage tank chassis leakage / seepage monitoring. Summary of the invention

[0004] In order to solve the above-mentioned problems, the present invention proposes: an array leak detection and prediction method for monitoring chassis leakage of a high-temperature molten salt storage tank, which arranges an array temperature sensor at the bottom of the tank to monitor the changes in the temperature field at the bottom of the tank in real time, and reconstructs the chassis temperature field data with the aid of a molten salt leakage model and a leakage database, thereby realizing the prediction and detection of chassis leakage of the tank.

[0005] Furthermore, the array temperature sensor is buried in the basic insulation material of the molten salt storage tank. The array temperature sensor is arranged above the insulation layer according to the tank bottom weld and the temperature field distribution, and is arranged unevenly in a mesh shape.

[0006] Furthermore, a planar array temperature measurement matrix arranged in the upper middle part of the lower insulation layer of the tank chassis uploads the sensor signal to the leakage analysis and early warning system through a multi-channel data acquisition device, senses the temperature field around the tank chassis in real time, and calculates the temperature field distribution.

[0007] Furthermore, the leakage analysis and early warning system collects environmental data and process switching data, and reconstructs the temperature field change trend according to the data changes and combines it with the temperature collection data to form a data model.

[0008] Furthermore, the real-time temperature field change model is compared and analyzed with the leakage model and database: when the temperature field distribution of the bottom of the molten salt storage tank changes due to corrosion, deformation, or environmental or process switching interference factors, the comparison and analysis system completes the focus on sensitive information based on the threshold condition match and change rate.

[0009] Furthermore, the planar array temperature sensors are connected to different acquisition channels respectively, and the temperature field change trend of the tank chassis is fully sensed through the multi-channel data acquisition device. With the help of the molten salt leakage model and leakage database, the leakage position of the molten salt tank chassis is predicted, discovered and located.

[0010] Furthermore, the early warning system analyzes changes in the temperature field, traces the source, filters out environmental and process factors, and finally issues an alarm.

[0011] Furthermore, the temperature field distribution is calculated as follows:

[0012] Heat conduction differential equation:

[0013]

[0014] k is the thermal conductivity of the material, q v is the heat flux, c p is the specific heat capacity of the material,

[0015] Take the temperature field test function:

[0016]

[0017] Where T1...Tn is the temperature distribution at discrete temperature points. According to the weighted residual method, the condition for the approximate solution of the temperature field to be close enough to the exact solution is that the weighted residual integral in the plane temperature field calculation domain is zero:

[0018]

[0019] W l is the weight coefficient of the discrete point, l≤n, and the corresponding boundary conditions are brought in. The basic equation for the finite element calculation of the plane temperature field is obtained by using the Green formula transformation:

[0020]

[0021] Perform variational calculations inside the chassis unit of the high-temperature molten salt storage tank:

[0022]

[0023] Calculate the partial derivative of the temperature function and substitute it into the variational formula to obtain:

[0024]

[0025] The beneficial effects of the present invention are:

[0026] 1) Array leak detection and prediction technology is suitable for monitoring and predicting leakage of high-temperature media within 600°C;

[0027] 2) The leakage alarm missed alarm rate is less than 10%, and the false alarm rate is less than 5%.

[0028] 3) The leakage alarm underreporting rate is less than 15%, and the false alarm rate is less than 10%.

[0029] 4) The leak point positioning accuracy is 25% of the temperature measurement array.

[0030] 5) This technical achievement fills the current gap in molten salt storage tank bottom plate leakage detection technology, and provides a safe technical guarantee for the future development of molten salt thermal storage applications in oil field steam injection.

[0031] The present invention monitors the health status of the tank chassis in real time, predicts and discovers leakage of the molten salt tank chassis as early as possible, and avoids the occurrence or expansion of leakage through early intervention, thereby reducing economic losses, safety risks and environmental pollution risks. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is the software diagram of the leakage analysis system of the present invention;

[0033] Figure 2 This is a typical array-type temperature measurement matrix layout diagram of the present invention. DETAILED DESCRIPTION

[0034] In order to make the technical means and objectives adopted by the present invention easy to understand, the present invention is further described below in combination with the specific implementation method. An array leak detection and prediction method for monitoring the chassis leakage of a high-temperature molten salt storage tank is provided. By setting an array temperature sensor at the bottom of the storage tank, the change of the temperature field at the bottom of the storage tank is monitored in real time, and the chassis temperature field is reconstructed with the aid of a molten salt leakage model and a leakage database, so as to realize the prediction and detection of the chassis leakage of the storage tank. This technology belongs to the field of instrument automation. It includes an array temperature sensor buried in the basic insulation material of the molten salt storage tank, and the array temperature sensor is arranged in a mesh-like uneven arrangement above the insulation layer according to the tank bottom weld and the temperature field distribution. The detection system also includes a multi-channel data acquisition device, which connects the planar array temperature sensor to different acquisition channels respectively, and predicts, discovers and locates the leakage position of the chassis of the molten salt storage tank by fully sensing the change trend of the temperature field of the tank chassis, assisted by the model and the leakage database. The present invention realizes the prediction, detection and accurate positioning of the leakage of the molten salt storage tank, and avoids the occurrence or expansion of the tank leakage accident.

[0035] The working principles and processes of each part of the system are as follows:

[0036] 1) A planar array temperature measurement matrix is ​​arranged in the middle and upper part of the insulation layer at the bottom of the tank chassis. The sensor signal is uploaded to the self-developed leakage analysis and early warning system through a multi-channel data collector to sense the temperature field around the tank chassis in real time and calculate the temperature field distribution;

[0037] 2) The leakage analysis and early warning system collects environmental data and process switching data, and reconstructs the temperature field change trend based on data changes and combines it with temperature collection data to form a data model;

[0038] 3) The perception system compares and analyzes the real-time temperature field change model with the leakage model and database;

[0039] 4) When the temperature field distribution of the bottom of the molten salt storage tank changes due to corrosion, deformation, or interference factors such as the environment and process switching, the comparison and analysis system completes the attention of sensitive information based on the threshold condition consistency and change rate;

[0040] The analysis and early warning system traces and locates the temperature according to the changes in the temperature field, filters out environmental and process factors, and finally issues an alarm.

[0041] The temperature field distribution is calculated as follows:

[0042] Heat conduction differential equation:

[0043]

[0044] k is the thermal conductivity of the material, q v is the heat flux, c p is the specific heat capacity of the material,

[0045] Take the temperature field test function (approximate solution of temperature field):

[0046]

[0047] Where T1...Tn is the temperature distribution at discrete temperature points. According to the weighted residual method, the condition for the approximate solution of the temperature field to be close enough to the exact solution is that the weighted residual integral in the plane temperature field calculation domain is zero:

[0048]

[0049] W l is the weight coefficient of the discrete point, l≤n, and the corresponding boundary conditions are brought in. The basic equation for the finite element calculation of the plane temperature field is obtained by using the Green formula transformation:

[0050]

[0051] Perform variational calculations inside the chassis unit of the high-temperature molten salt storage tank:

[0052]

[0053] Calculate the partial derivative of the temperature function and substitute it into the variational formula to obtain:

[0054]

[0055] The advantages of the present invention are as follows:

[0056] 1) Array leak detection and prediction technology is suitable for monitoring and predicting leakage of high-temperature media within 600°C;

[0057] 2) The leakage alarm missed alarm rate is less than 10%, and the false alarm rate is less than 5%.

[0058] 3) The leakage alarm underreporting rate is less than 15%, and the false alarm rate is less than 10%.

[0059] 4) The leak point positioning accuracy is 25% of the temperature measurement array.

[0060] 5) This invention fills the current gap in molten salt storage tank bottom plate leakage detection technology, and provides a safe technical guarantee for the future development of molten salt heat storage applications in oil field steam injection.

[0061] Take the insulation layer leakage monitoring of 560℃ molten salt medium storage tank as an example:

[0062] A plane array temperature measurement matrix (3m / point) is arranged in the middle and upper part of the insulation layer under the tank chassis. The sensor signal is uploaded to the self-developed leakage analysis and early warning system through a multi-channel data collector to sense the temperature field around the tank chassis in real time and calculate the temperature field distribution.

[0063] Process switching impact;

[0064] Impact of ambient temperature changes;

[0065] When leakage occurs at a certain point, the impact is 1L / s;

[0066] The positioning points are from the periphery of the tank, which is an environmental factor; the positioning points all change, which is a process factor; the positioning points are from inside the tank, which is a leakage factor.

[0067] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. An array leak detection and prediction method for chassis leakage monitoring of high-temperature molten salt storage tanks, characterized in that: An array temperature sensor is installed at the bottom of the tank to monitor the changes in the temperature field at the bottom of the tank in real time. With the help of the molten salt leakage model and leakage database, the chassis temperature field data is reconstructed to realize the prediction and detection of tank chassis leakage.

2. The array leak detection and prediction method for monitoring chassis leakage of high-temperature molten salt storage tanks according to claim 1, characterized in that: The array temperature sensor is buried in the basic insulation material of the molten salt storage tank. The array temperature sensor is arranged above the insulation layer according to the tank bottom weld and the temperature field distribution, and is arranged unevenly in a mesh shape.

3. The array leak detection and prediction method for monitoring chassis leakage of high-temperature molten salt storage tanks according to claim 2, characterized in that: The planar array temperature measurement matrix arranged in the upper middle part of the lower insulation layer of the tank chassis uploads the sensor signal to the leakage analysis and early warning system through a multi-channel data acquisition device, senses the temperature field around the tank chassis in real time, and calculates the temperature field distribution.

4. The array leak detection and prediction method for monitoring chassis leakage of high-temperature molten salt storage tanks according to claim 3, characterized in that: The leakage analysis and early warning system collects environmental data and process switching data, and reconstructs the temperature field change trend based on data changes and combines it with temperature collection data to form a data model.

5. The array leak detection and prediction method for monitoring chassis leakage of high-temperature molten salt storage tanks according to claim 4, characterized in that: Compare and analyze the real-time temperature field change model with the molten salt leakage model and leakage database: When the temperature field distribution of the bottom of the molten salt storage tank changes due to corrosion, deformation, or environmental or process switching interference factors, the comparison and analysis early warning system completes the focus on sensitive information based on the threshold condition match and change rate.

6. The array leak detection and prediction method for monitoring chassis leakage of high-temperature molten salt storage tanks according to claim 5, characterized in that: The planar array temperature sensors are connected to different acquisition channels respectively, and the temperature field change trend of the tank chassis is fully sensed through the multi-channel data acquisition device. Assisted by the molten salt leakage model and leakage database, the leakage position of the molten salt tank chassis is predicted, discovered and located.

7. The array leak detection and prediction method for monitoring chassis leakage of high-temperature molten salt storage tanks according to claim 6, characterized in that: The analysis and early warning system traces and locates the temperature according to the changes in the temperature field, filters out environmental and process factors, and finally issues an alarm.

8. The array leak detection and prediction method for monitoring chassis leakage of high-temperature molten salt storage tanks according to claim 3, characterized in that: The temperature field distribution is calculated as follows: Heat conduction differential equation: k is the thermal conductivity of the material, q v is the heat flux, c p is the specific heat capacity of the material, Take the temperature field test function: Where T1.......T n is the temperature distribution at discrete temperature points. According to the weighted residual method, the condition for the approximate solution of the temperature field to be close enough to the exact solution is that the weighted residual integral in the plane temperature field calculation domain is zero: W l is the weight coefficient of the discrete point, l≤n, and the corresponding boundary conditions are brought in. The basic equation for the finite element calculation of the plane temperature field is obtained by using the Green formula transformation: Perform variational calculations inside the chassis unit of the high-temperature molten salt storage tank: Calculate the partial derivative of the temperature function and substitute it into the variational formula to obtain:

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