Supercritical carbon dioxide pipeline flow guarantee experiment testing system and method

Abstract

The invention discloses a supercritical carbon dioxide pipeline flow guarantee experimental test system and method.The supercritical carbon dioxide pipeline flow guarantee experimental test system comprises a transportation stopping test module, a leakage test module, a carbon dioxide supply module and a control module, and the transportation stopping test module comprises a trunk pipeline, a high-speed camera and a visible pipe section; the carbon dioxide supply module is connected with one end of the main pipeline and used for conveying needed carbon dioxide into the main pipeline, the visible pipe section is installed on the main pipeline, the first valve is installed at the starting end of the main pipeline, the second valve is installed at the terminal end of the main pipeline, and the high-speed camera is arranged over the visible pipe section. The high-speed camera, the first valve and the second valve are all connected with the control module, the designed transmission stopping test module and the designed leakage test module can test transmission stopping and leakage respectively, transmission stopping behaviors, the influence range of the low-temperature effect and the dangerous concentration diffusion range of carbon dioxide under different working conditions can be tested, and the detection accuracy is improved. And experimental data support and quantitative guidance are provided for actual engineering.

Description

Technical Field

[0001] The invention relates to the technical field of carbon dioxide transportation, and in particular to a supercritical carbon dioxide pipeline flow assurance experimental testing system and method. Background Art

[0002] Currently, carbon capture, utilization and storage (CCUS) technology provides a promising way to reduce carbon dioxide emissions and address climate change. In the CCUS technology chain, pipeline transportation is the most economical and effective way to transport carbon dioxide.

[0003] Since the physical properties of carbon dioxide are significantly different from those of crude oil and natural gas, the existing pipeline operation technology cannot be directly applied. The ultra-high pressure and ultra-low temperature caused by the sudden change of carbon dioxide phase can cause pipeline damage and harm to the surrounding areas, which brings challenges to pipeline operation. When put into production, the core technology of supercritical (between gas and liquid phases) carbon dioxide pipeline flow assurance provides effective guarantee for safe and reliable transportation. However, there is little research on the shutdown process and accidental leakage during pipeline transportation in this technology, so it is impossible to accurately obtain the phase changes of carbon dioxide during pipeline shutdown and leakage, the scope of influence of low temperature effects, and the diffusion range of dangerous carbon dioxide concentrations. There is a lack of experimental data support, and it is impossible to provide quantitative guidance for engineering design and standard formulation.

[0004] Therefore, a new supercritical carbon dioxide pipeline flow assurance experimental test system and method are urgently needed to solve the above technical problems. Summary of the invention

[0005] The present invention aims to solve the above technical problem, that is, to solve the problem that there is little research on the shutdown conditions and leakage conditions in the pipeline transportation process in the prior art, so that it is impossible to accurately obtain the phase changes of carbon dioxide in the pipeline leakage and shutdown process, the influence range of the low temperature effect and the diffusion range of the dangerous concentration of carbon dioxide, lack of experimental data support, and unable to provide quantitative guidance for engineering design and standard formulation.

[0006] To this end, in a first aspect, the present invention provides a supercritical carbon dioxide pipeline flow assurance experimental test system, comprising a stop-transmission test module, a carbon dioxide supply module and a control module, the stop-transmission test module comprising a trunk pipeline, a high-speed camera and a visible pipe section, the carbon dioxide supply module is connected to one end of the trunk pipeline for conveying required carbon dioxide into the trunk pipeline, the visible pipe section is installed on the trunk pipeline, a first valve is installed at the starting end of the trunk pipeline, a second valve is installed at the terminal end of the trunk pipeline, the high-speed camera is arranged directly above the visible pipe section, and the high-speed camera, the first valve and the second valve are all connected to the control module.

[0007] In the specific implementation manner of the above-mentioned supercritical carbon dioxide pipeline flow assurance experimental test system, the supercritical carbon dioxide pipeline flow assurance experimental test system further includes a temperature control module, and the temperature control module is configured to be able to change the initial state of the carbon dioxide in the main pipeline and the carbon dioxide transported by the carbon dioxide supply module into the main pipeline through temperature control.

[0008] In the specific implementation manner of the above-mentioned supercritical carbon dioxide pipeline flow assurance experimental test system, the carbon dioxide supply module includes a storage tank and a carbon dioxide tanker. The gas-phase outlet of the carbon dioxide tanker is connected to the gas inlet of the storage tank, and the liquid-phase outlet of the carbon dioxide tanker is connected to the liquid inlet of the storage tank.

[0009] In the specific implementation manner of the above-mentioned supercritical carbon dioxide pipeline flow assurance experimental test system, the temperature control module includes a temperature control box, a first heat tracing tape, and a second heat tracing tape. The first heat tracing tape is wound around the main pipeline, the second heat tracing tape is wound around the outer wall of the storage tank, and both the first heat tracing tape and the second heat tracing tape are connected to the temperature control box.

[0010] In the specific implementation manner of the above-mentioned supercritical carbon dioxide pipeline flow assurance experimental test system, a plurality of first pressure sensors and a plurality of first temperature sensors are installed along the length direction of the main pipeline, and both the first pressure sensors and the first temperature sensors are communicatively connected to the control module.

[0011] In the specific implementation manner of the above-mentioned supercritical carbon dioxide pipeline flow assurance experimental test system, a pressure gauge and a second temperature sensor are installed on the storage tank. A safety outlet is provided on the storage tank, and a safety valve is installed on the safety outlet.

[0012] In the specific implementation manner of the above-mentioned supercritical carbon dioxide pipeline flow assurance experimental test system, the supercritical carbon dioxide pipeline flow assurance experimental test system further includes a leakage test module. The leakage test module includes a leakage test pipeline, a test box, and an optical fiber rack. A plurality of air holes are provided on the outer peripheral wall of the test box. The top end of the test box is an open structure, and the test box is filled with soil. One end of the leakage test pipeline is connected to the main pipeline, and the other end of the leakage test pipeline extends into the test box and is in a closed state. A leakage hole is provided on the leakage test pipeline in the test box, and a bursting disc is installed in the leakage hole. The optical fiber rack is embedded in the test box, and an optical fiber temperature sensor is installed on the optical fiber rack.

[0013] In the specific implementation manner of the above-mentioned supercritical carbon dioxide pipeline flow assurance experimental test system, several carbon dioxide concentration sensors are placed on the top of the test box, and a high-definition camera is arranged above the test box. Both the carbon dioxide concentration sensor and the high-definition camera are communicatively connected to the control module.

[0014] In a second aspect, the present invention also provides a shutdown experiment test method based on the supercritical carbon dioxide pipeline flow assurance experimental test system described in any one of the first aspects, characterized by including the following steps: Control the first valve to open and the second valve to close through the control module, and use the carbon dioxide supply module to fill the main pipeline with liquid-phase carbon dioxide until it is full; Use the temperature regulation module to heat the main pipeline and obtain the temperature and pressure information inside the main pipeline; Use the control module to judge the magnitudes of the temperature value and the pressure value and the corresponding experimental condition requirement values; If both the temperature value and the pressure value are equal to the corresponding experimental condition requirement values, then keep the temperature and pressure values unchanged through the temperature regulation module and stand still for a first set time; After reaching the first set time, conduct a shutdown experiment test, specifically including: closing the first valve through the control module, controlling the main pipeline to be at the expected ambient temperature through the temperature regulation module, so that the carbon dioxide inside the main pipeline undergoes natural temperature drop. During the natural temperature drop, use a high-speed camera to take pictures inside the visible pipe section to obtain the liquid holdup situation and phase state inside the main pipeline after cooling and gasification, and record the changes in the pressure and temperature values of the carbon dioxide inside the main pipeline in real time through the control module until the temperature inside the main pipeline drops to the expected ambient temperature.

[0015] In a third aspect, the present invention also provides a leakage experiment test method based on the supercritical carbon dioxide pipeline flow assurance experimental test system described in any one of the first aspects, characterized in that the leakage experiment test method includes the following steps: Control the first valve to open and the second valve to close through the control module, and use a tanker to fill the storage tank and the main pipeline with liquid-phase carbon dioxide until it is full; Use the temperature regulation module to heat the storage tank and the main pipeline and obtain the temperature and pressure information inside the storage tank and the main pipeline; Use the control module to judge the magnitudes of the temperature value and the pressure value inside the storage tank and the main pipeline and the corresponding experimental condition requirement values; If both the temperature value and the pressure value inside the storage tank and the main pipeline are equal to the corresponding experimental condition requirement values, then keep the temperature and pressure values unchanged through the temperature regulation module and stand still for a first set time; After reaching the first set time, a leakage test experiment is carried out, specifically including: The control module opens the second valve and starts timing, and carbon dioxide leaks out from the leakage hole; During the leakage process, the temperature value inside the test chamber and the carbon dioxide concentration value on the surface of the test chamber are obtained in real time; the visible cloud during the leakage process and the characteristics of the soil surface inside the test chamber are obtained through a high-definition camera; When the pressure value in the main pipeline drops to the normal temperature pressure, it is determined that the leakage is complete, and the control module controls the first valve and the second valve to close, and the timing ends.

[0016] Compared with the prior art, the beneficial effects of the present invention are: The shutdown test module and the leakage test module designed by the present invention can respectively test shutdown and leakage, and can test the shutdown behavior under different pipeline transportation temperatures, different pipeline transportation pressures, and different ambient temperatures, which helps to obtain the phase state migration path of carbon dioxide fluid, the initial gasification pressure and temperature, the pressure drop corresponding to the unit temperature drop, the safe shutdown time, the change law of the liquid holdup after gasification, etc. under different working conditions; it can also test the influence range of the low-temperature effect and the diffusion range of the carbon dioxide dangerous concentration under different pipeline transportation temperatures, different pipeline transportation pressures, different ambient temperatures, different leakage types, different leakage sizes, different leakage directions, different soil types, and different leakage times, providing experimental data support and quantitative guidance for engineering design and standard formulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. In the drawings: Figure 1 is the overall structural schematic diagram of the supercritical carbon dioxide pipeline flow assurance experimental test system provided by the present invention; Figure 2 is the structural schematic diagram with an erosion hole type leakage hole; Figure 3 is the structural schematic diagram with a crack type leakage hole; Figure 4 is the layout schematic diagram of the leakage test pipeline and the fiber optic temperature sensor in the test chamber; Figure 5 is Figure 3 the top view of the fiber optic rack in

[0018] List of reference numerals: 1. Carbon dioxide tanker; 2. Gas-phase injection pipeline; 3. Liquid-phase injection pipeline; 4. First screw valve; 5. Second screw valve; 6. Storage tank; 7. Pressure gauge; 8. Safety valve; 9. Second heat tracing tape; 10. Second temperature sensor; 11. Temperature control box; 12. First valve; 13. Main pipeline; 14. First heat tracing tape; 15. First pressure sensor; 16. First temperature sensor; 17. Data collector; 18. Computer; 19. First flange; 20. Visual pipe section; 21. High-definition camera; 22. High-speed camera; 23. Carbon dioxide concentration sensor; 24. Optical fiber temperature sensor; 25. Second valve; 26. Second flange; 27. Leakage test pipeline; 28. Plugging flange; 29. Test box; 30. Leakage hole; 31. Optical fiber rack. Detailed implementation manners

[0019] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Apparently, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0020] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the system or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be construed as a limitation of the present invention. In addition, the use of the terms "first", "second", etc. to limit the components is only for the convenience of distinguishing the above components. Without further statement, the above terms have no special meaning and cannot be construed as indicating or implying relative importance.

[0021] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "installed", "set", "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0022] The present invention relates to the field of carbon dioxide transportation technology, and in particular to a supercritical carbon dioxide pipeline flow assurance experimental test system and method. The purpose is to solve the problem that there is little research on the leakage and diffusion characteristics and stop characteristics of supercritical carbon dioxide in the process of pipeline transportation during leakage and stop, so that it is impossible to accurately obtain the pressure change, temperature change, carbon dioxide phase change, the influence range of carbon dioxide low temperature effect and the diffusion range of dangerous concentration of carbon dioxide in the pipeline during the pipeline leakage and stop, lack of experimental data support, and unable to provide quantitative guidance for engineering design and standard formulation. For this purpose, the supercritical carbon dioxide pipeline flow assurance experimental test system provided by the present invention includes a stop test module, a carbon dioxide supply module and a control module. The stop test module includes a trunk pipeline, a high-speed camera and a visual pipe section. The carbon dioxide supply module is connected to one end of the trunk pipeline for conveying the required carbon dioxide into the trunk pipeline. The visual pipe section is installed on the trunk pipeline. The starting end of the trunk pipeline is installed with a first valve, and the terminal end of the trunk pipeline is installed with a second valve. The high-speed camera is arranged directly above the visual pipe section. The high-speed camera, the first valve and the second valve are all connected to the control module. The stop test module and the leakage test module designed by the present invention can respectively Testing of shutdown and leakage can test the shutdown behavior under different pipeline temperatures, different pipeline pressures, and different ambient temperatures, which is helpful to obtain the phase migration path of carbon dioxide fluid after shutdown under different working conditions, the initial gasification pressure and temperature, the pressure drop corresponding to the unit temperature drop, the safe shutdown time, the change law of liquid holdup after gasification occurs, etc.; it can also test the influence range of low temperature effect and the diffusion range of dangerous carbon dioxide concentration under different pipeline temperatures, different pipeline pressures, different ambient temperatures, different leakage types, different leakage sizes, different leakage directions, different soil types, and different leakage times, provide experimental data support, and provide quantitative guidance for engineering design and standard formulation.

[0023] The supercritical carbon dioxide pipeline flow assurance experimental test system and method provided by the embodiments of the present invention are described in detail below in conjunction with the accompanying drawings.

[0024] See also Figure 1 The present invention provides a supercritical carbon dioxide pipeline flow assurance experimental test system, comprising a stop test module, a carbon dioxide supply module and a control module. The stop test module comprises a trunk pipeline 13, a high-speed camera 22 and a visual pipe section 20. The carbon dioxide supply module is connected to one end of the trunk pipeline 13 for conveying required carbon dioxide into the trunk pipeline 13. The visual pipe section 20 is installed on the trunk pipeline 13. The starting end of the trunk pipeline 13 is installed with a first valve 12, and the terminal end of the trunk pipeline 13 is installed with a second valve 25. The high-speed camera 22 is arranged directly above the visual pipe section 20, and the high-speed camera 22, the first valve 12 and the second valve 25 are all connected to the control module.

[0025] Specifically, the control module includes a data collector 17 and a computer 18. The data collected by the data collector 17 is transmitted to the computer 18 for processing. The high-speed camera 22, the first valve 12, and the second valve 25 are all communicatively connected to the data collector 17. The first valve 12 and the second valve 25 can both be, but are not limited to, solenoid valves. The visible pipe section 20 is made of sapphire material, and the high-speed camera 22 can capture the phase change of carbon dioxide in the visible pipe section 20 during the shutdown process. Both ends of the visible pipe section 20 are detachably and fixedly connected to the main pipeline 13 through the first flange 19.

[0026] In the above embodiment, preferably, continue to refer to Figure 1 , the carbon dioxide supply module includes a storage tank 6 and a carbon dioxide tanker 1. The gas-phase outlet of the carbon dioxide tanker 1 is connected to the gas inlet of the storage tank 6, and the liquid-phase outlet of the carbon dioxide tanker 1 is connected to the liquid inlet of the storage tank 6.

[0027] Specifically, the gas-phase outlet of the carbon dioxide tanker 1 is connected to the gas inlet through the gas injection pipeline 2, and a first screw valve 4 is installed on the gas injection pipeline 2. The liquid-phase outlet of the carbon dioxide tanker 1 is connected to the liquid inlet of the storage tank 6 through the liquid injection pipeline 3, and a second screw valve 5 is installed on the liquid injection pipeline 3. During the simulation experiment, the second screw valve 5 is opened, and using the built-in back pressure of the tanker, liquid-phase carbon dioxide is filled into the storage tank 6 from the liquid-phase outlet of the carbon dioxide. After the storage tank 6 is full, the second screw valve 5 is closed.

[0028] In the above embodiment, a plurality of first pressure sensors 15 and a plurality of first temperature sensors 16 are installed along the length direction of the main pipeline 13. The first pressure sensors 15 and the first temperature sensors 16 are both communicatively connected to the control module. That is, the first pressure sensors 15 and the first temperature sensors 16 are both communicatively connected to the data collector 17. Specifically, one first pressure sensor 15 and one first temperature sensor 16 are installed at both ends of the main pipeline 13. Through the first pressure sensors 15 and the first temperature sensors 16, the temperature and pressure changes at various positions along the main pipeline 13 can be monitored, and then the phase state of carbon dioxide at that position can be calculated by the temperature and pressure. The pressure and temperature data in the main pipeline 13 can be read through the data collector 17, which is convenient for controlling the initial state of carbon dioxide and monitoring the pressure and temperature changes in the main pipeline 13 during the test process.

[0029] In one embodiment, continue to refer to Figure 1 , the supercritical carbon dioxide pipeline flow assurance experimental test system further includes a temperature control module, and the temperature control module is set to be able to change the initial state of the carbon dioxide in the main pipeline 13 and the carbon dioxide transported from the carbon dioxide supply module to the main pipeline 13 through temperature control.

[0030] In a specific embodiment, the temperature control module includes a temperature control box 11, a first heat tracing tape 14, a first heat insulation layer, a second heat tracing tape 9 and a second heat insulation layer. The first heat tracing tape 14 is wound around the main pipeline 13 and is wrapped by the first heat insulation layer. The second heat tracing tape 9 is wound around the outer wall of the storage tank 6 and is wrapped by the second heat insulation layer. Both the first heat tracing tape and the second heat tracing tape 9 are connected to the temperature control box 11. The opening and closing of the heating of the first heat tracing tape 14 and the second heat tracing tape 9 and the temperature are set and controlled by the temperature control box 11. The heat insulation layer is composed of rock wool and fireproof and waterproof fiberglass cloth, with a thickness of about 60 mm. By changing the temperature, the pressure of carbon dioxide in the storage tank and the main pipeline is changed, so that carbon dioxide reaches the initial conditions set in the experiment.

[0031] In one embodiment, a pressure gauge 7 and a second temperature sensor 10 are installed on the storage tank 6. A safety outlet is provided on the storage tank 6, and a safety valve 8 is installed on the safety outlet. The pressure gauge 7 is used to detect the pressure in the storage tank 6, and the second temperature sensor 10 is used to detect the temperature in the storage tank 6. During the heating process of the storage tank 6, when the pressure in the storage tank 6 reaches the preset pressure while the temperature is lower than the preset temperature, the pressure can be relieved through the safety valve 8, which can effectively prevent overpressure in the storage tank 6 and avoid accidents. By controlling the heating temperature of the first heat tracing tape and the second heat tracing tape 9 through the temperature control box 11, the storage tank 6 and the main pipeline 13 are heated respectively to make their temperature and pressure meet the requirements of the experimental conditions.

[0032] When conducting the shutdown test experiment: open the first valve 12 at the starting end of the main pipeline 13 and keep the second valve 25 at the terminal end of the main pipeline 13 closed. The carbon dioxide in the storage tank 6 flows into the main pipeline 13. When the reading of the pressure gauge 7 on the storage tank 6 is almost unchanged, close the first valve 12. Control the temperature of the first heat tracing tape through the temperature control box 11, and increase the pressure in the main pipeline 13 by raising the temperature, so as to reach the target working condition. Specifically, as the temperature rises, the thermal motion of carbon dioxide molecules intensifies, causing the low-temperature liquid-phase carbon dioxide to transform into high-temperature and high-pressure liquid-phase carbon dioxide, dense-phase carbon dioxide or supercritical-phase carbon dioxide.

[0033] In one embodiment, refer to Figure 1, the supercritical carbon dioxide pipeline flow assurance experimental test system further includes a leakage test module. The leakage test module includes a leakage test pipeline 27, a test box 29, and an optical fiber rack 31. A plurality of air outlet holes are provided on the outer peripheral wall of the test box 29. The top end of the test box 29 is an open structure, and the test box 29 is filled with soil. One end of the leakage test pipeline 27 is connected to the main pipeline 13, and the other end of the leakage test pipeline 27 extends into the test box 29 and is in a closed state. A leakage hole 30 is provided on the leakage test pipeline 27 in the test box, and a bursting disc is installed in the leakage hole 30. The optical fiber rack 31 is embedded in the test box 29, and an optical fiber temperature sensor 24 is installed on the optical fiber rack 31.

[0034] Specifically, the test box includes a frame and a wire mesh. The wire mesh is respectively installed on the side openings of the frame to ensure supporting the soil while not affecting the diffusion of carbon dioxide in all directions. One end of the leakage test pipeline 27 is detachably connected to the main pipeline 13 through a second flange 26. The other end of the leakage test pipeline 27 is installed with a sealing flange 28. The second flange 26 helps to adjust the orientation of the leakage hole of the leakage test pipeline 27, thereby realizing the carbon dioxide leakage experiment in different leakage directions. At the same time, different leakage experiments can also be tested by replacing the leakage test pipeline 27 with different leakage holes 30. The bursting disc is placed inside the test leakage pipe section and is arranged closely to the leakage hole. During the leakage experiment, when the internal pressure of the test leakage pipe section increases to the preset experimental pressure, the bursting disc bursts immediately under the action of the internal and external pressure difference, thereby releasing the seal of the leakage hole, and carbon dioxide leaks into the soil of the test box 29 from the leakage hole instantaneously.

[0035] In the above embodiment, preferably, refer to Figure 1 , Figure 4 and Figure 5 , the number of the optical fiber temperature sensors 24 is multiple and they are arranged at equal intervals up and down. Each optical fiber temperature sensor 24 is wound around the optical fiber rack 31 in a circular arrangement. The optical fiber temperature sensors 24 are arranged above and below the leakage test pipeline 27 to detect the actual temperature around the leakage hole 30. Specifically, the optical fiber rack 31 includes a vertical rod and an annular rod. A plurality of annular rods arranged at equal intervals up and down are fixedly sleeved on the vertical rod, and the optical fiber temperature sensors 24 are wound around the annular rod.

[0036] In one embodiment, several carbon dioxide concentration sensors 23 are placed on the top of the test chamber 29, and the carbon dioxide concentration sensors 23 are communicatively connected to the control module. During the leakage experiment, the surrounding carbon dioxide concentration is detected by the carbon dioxide concentration sensors 23. Several carbon dioxide concentration sensors 23 can also be placed around the test chamber 29 to detect the carbon dioxide concentration around the test chamber 29. Since high carbon dioxide concentration poses a risk of asphyxiation when inhaled by people, by monitoring the change in carbon dioxide concentration, it can ensure that the staff can approach the experimental test system without endangering their physical health, thus ensuring personal safety. The specific arrangement position of the carbon dioxide concentration sensors 23 is set according to the actual test situation and environment.

[0037] In one embodiment, a high-definition camera 21 is provided above the test chamber 29 for photographing the generated visible cloud form and the characteristics of the soil in the test chamber 29 after carbon dioxide leakage, such as soil splashing conditions, dry ice ball characteristics, etc.

[0038] In the present application, multiple leakage test pipes 27 need to be customized. Both the test pipes and the main pipeline 13 are S30403 stainless steel pipes with a DN100 diameter. Different types and sizes of leakage holes are opened on each leakage test pipe 27. Exemplarily, the leakage holes include corrosion hole types (diameter d = 2, 4, 6, 8 mm) and crack-type leakage holes (a = 2 mm, c / a = 2, 3, 4), as Figures 2 - 3 shown.

[0039] In addition, in the present application, a storage tank 6 and a second heat tracing tape 9 are provided on the storage tank 6, which provides a large amount of carbon dioxide under the same working conditions for the leakage test experiment, ensures the effective test time, and is conducive to making the leakage test experiment results more in line with the actual situation.

[0040] In another embodiment, the present invention also provides a shutdown experiment test method based on the supercritical carbon dioxide pipeline flow assurance experimental test system described in any one of the above embodiments, including the following steps: Control the first valve to open and the second valve to close through the control module, and use the carbon dioxide supply module to fill the main pipeline with liquid-phase carbon dioxide until it is full; Use the temperature regulation module to heat up the main pipeline and obtain the temperature and pressure information inside the main pipeline; Use the control module to judge the magnitudes of the temperature value and the pressure value and the corresponding experimental condition requirement values; If both the temperature value and the pressure value are equal to the corresponding experimental condition requirement values, then keep the temperature and pressure values unchanged through the temperature regulation module and stand still for a first set time; After reaching the first set time, a shutdown experiment test is carried out, which specifically includes: closing the first valve through the control module, controlling the main pipeline to be at the expected ambient temperature through the temperature regulation module, so that the carbon dioxide in the main pipeline undergoes natural temperature drop. During the natural temperature drop, a high-speed camera is used to photograph the inside of the visible pipe section to obtain the change in the liquid holdup rate and phase change in the main pipeline after cooling and gasification through the photographed images, and the pressure and temperature values of the carbon dioxide in the main pipeline are recorded in real time through the cooperation of the first temperature sensor, the first pressure sensor and the control module until the temperature in the main pipeline drops to the expected ambient temperature.

[0041] Combined with the supercritical carbon dioxide pipeline flow assurance experiment test system described in the above embodiments, the process of carbon dioxide pipeline shutdown using this experiment test system will be elaborated in detail below.

[0042] The process of carrying out the shutdown experiment test is specifically as follows: The first step is to fill carbon dioxide: close the first screw valve 4 and the second valve 25, open the second screw valve 5, and transport liquid-phase carbon dioxide from the tanker to the storage tank 6 and the main pipeline 13. After filling, close the second screw valve 5. The tanker has a built-in back pressure of 2 MPa, and no other pressurization methods are required. Just close the valve after the pressure in the tanker and the pipeline is balanced. The density of carbon dioxide can be calculated through the temperature and pressure of the fluid in the pipeline, and then the filling mass of carbon dioxide can be calculated.

[0043] The second step is to raise the temperature and pressure to the expected working condition: use the first heating tape and the second heating tape 9 to heat the storage tank 6 and the main pipeline 13 so that their temperature and pressure reach the requirements of the experimental working condition. Keep the temperature and pressure unchanged through the temperature control box 11, and let it stand for the first set time (which can be one hour), then the shutdown test experiment can be carried out.

[0044] Shutdown test experiment: Close the first valve 12, adjust the temperature control box 11 to the expected ambient temperature, and let it undergo natural temperature drop. Use the high-speed camera 22 to photograph the change in the liquid holdup rate and phase change in the pipeline after cooling and gasification, and record the change in the pressure and temperature of the carbon dioxide in the main pipeline 13 through the data collector 17. When the temperature in the pipeline drops to the ambient temperature, the first group of shutdown experiments ends. Then raise the temperature to the expected working condition again, and then simulate and test the shutdown behavior of the supercritical carbon dioxide pipeline under different working conditions, which helps to obtain the phase migration path of the carbon dioxide fluid after shutdown, the initial gasification pressure and temperature, the pressure drop corresponding to the unit temperature drop, the change law of the liquid holdup rate after gasification, etc. under different working conditions.

[0045] In another embodiment, the present invention also provides a leakage experiment test method based on the supercritical carbon dioxide pipeline flow assurance experiment test system described in any one of the above embodiments. The leakage experiment test method includes the following steps: The control module controls the opening of the first valve and the closing of the second valve, and a tank truck is used to fill the storage tank and the main pipeline with liquid carbon dioxide until it is full; The temperature control module is used to heat up the storage tank and the main pipeline and obtain the temperature and pressure information inside the storage tank and the main pipeline; The control module is used to judge the magnitudes of the temperature value and the pressure value inside the storage tank and the main pipeline and the required values corresponding to the experimental conditions; If both the temperature value and the pressure value inside the storage tank and the main pipeline are equal to the required values corresponding to the experimental conditions, then the temperature control module keeps the temperature and pressure values unchanged and stands still for the first set time; After reaching the first set time, a leakage test experiment is carried out, specifically including: The control module opens the second valve and starts timing, and the leakage time can be obtained, and carbon dioxide leaks out from the leakage hole; During the leakage process, the temperature value inside the test box and the carbon dioxide concentration value on the surface of the test box are obtained in real time; the visible cloud during the leakage process and the characteristics of the soil inside the test box are obtained through a high-definition camera; When the pressure value inside the obtained main pipeline drops to the normal temperature pressure, it is determined that the leakage is completed, and the control module controls the first valve and the second valve to close, the timing ends, and the leakage time can be obtained.

[0046] Combined with the supercritical carbon dioxide pipeline flow assurance experimental test system described in the above embodiments, the process of carbon dioxide pipeline leakage using this experimental test system is elaborated in detail below.

[0047] Before carrying out the leakage test experiment, the sand box and the leakage pipeline need to be prepared and installed. The specific steps are as follows: First step, take a small amount of sample sand to test the soil moisture content, dry the sample sand for 2 hours, compare the mass of the sand sample before and after drying, and then determine the soil moisture content; carry out a small-scale sand filling experiment in the laboratory, and use the ring knife cutting method to test the soil sample porosity. Transfer the soil sample to be tested into a bottomed ring knife with the same volume, place the bottomed ring knife containing the soil sample on an analytical balance, and use a rubber dropper to add water to the ring channel until the liquid level reaches the top of the ring knife. At this time, the soil sample reaches the saturated state and the mass is weighed. According to the weighed mass and the volume of the ring channel, parameters such as soil porosity and soil density can be obtained.

[0048] Second step, remove the second flange 26 connecting the leakage test pipeline 27 and the main pipeline 13, rotate the leakage hole 30 to the set position, and then install it again.

[0049] In the third step, place the leakage test pipeline 27 inside the test box 29. Fix the fiber optic temperature sensor 24 to the fiber optic rack 31 using nylon straps. Then, lead out the data transmission line connected to the fiber optic temperature sensor 24 from the test box 29 and connect it to the data collector 17.

[0050] In the fourth step, fill the test box 29 with soil. For every 10 cm of natural sand filling, compact it with a heavy object once until the soil burial depth preset in the experiment is reached. The test box 29 needs to be left standing naturally for 2 h to rely on natural gravity to reduce the impact of excessive porosity during the sand filling process on the experimental results.

[0051] After the sand box and the leakage pipeline are installed, perform the following steps: In the fifth step, fill with carbon dioxide: Close the first screw valve 4 and the second valve, open the second screw valve 5, and transport liquid-phase carbon dioxide from the tanker to the storage tank 6 and the main pipeline 13. After filling, close the second screw valve 5.

[0052] In the sixth step, raise the temperature and pressure to the expected working conditions: Use the first heating tape and the second heating tape 9 to heat the storage tank 6 and the main pipeline 13 so that their temperature and pressure reach the requirements of the experimental working conditions. After reaching the requirements, keep the temperature and pressure constant through the temperature control box 11 and leave it standing for the first set time (which can be one hour), then the leakage test experiment can be carried out.

[0053] In the seventh step, leakage test experiment: Open the second valve 25 and start timing to obtain the leakage time. Carbon dioxide quickly enters the leakage test pipeline 27. The bursting disc breaks under the action of the pressure difference inside and outside the pipe section. Record the temperature change inside the test box 29, the carbon dioxide concentration change on the surface and around the test box 29 through the fiber optic temperature sensor 24 and the carbon dioxide concentration sensor 23, and record the visible cloud generated during the leakage process and the appearance characteristics of the soil washed away inside the test box 29 through the high-definition camera 21; thereby simulate and test the leakage behavior of the supercritical carbon dioxide pipeline under different working conditions, which helps to obtain the temperature field change of the carbon dioxide leakage domain under different working conditions, clarify the growth laws and dominant factors of the jet cavity, dry ice ball, and frozen soil layer, fill the understanding of the leakage and diffusion characteristics of buried pipelines, and at the same time give the high-consequence range of carbon dioxide leakage to guide leakage monitoring and emergency rescue.

[0054] In the eighth step, when the pressure inside the main pipeline 13 drops to atmospheric pressure, it is considered that the leakage is complete. Close the first valve 12 and the second valve 25. The operator wears a gas mask and anti-freezing gloves to clean the soil in the test box 29 layer by layer and record the frozen soil characteristics, dry ice characteristics, jet cavity characteristics, etc. in the soil.

[0055] In the ninth step, when the carbon dioxide concentration in the air drops to the initial value, the leakage test experiment can be repeated according to the above steps.

[0056] During the construction of the experimental test system of this application, the storage tank and the main pipeline are purged to discharge impurities and air. Specifically: First, close all valves in the system, open the first valve 12 and the second valve 25, then open the first screw valve 4 to purge the storage tank and the main pipeline. After purging, close the second valve. After the construction is completed, check the airtightness of the system; check whether the pressure and the pressure sensor are properly connected to the data acquisition system, and check whether the data is normal. The steps for purging the pipeline are specifically as follows: Pass gaseous carbon dioxide into the storage tank 6, the main pipeline 13, and the leak test pipeline 27 through a tanker truck to discharge the air and impurities in the pipeline.

[0057] It should be noted that a shutdown test has been carried out before the first leak test. Therefore, when conducting the first leak test, it is not necessary to perform the step of filling the storage tank and the main pipeline with carbon dioxide because they have been filled during the shutdown test.

[0058] In the embodiment of this application, for the shutdown test, a high-speed camera 22 is used to capture the change in the liquid holdup in the main pipeline 13 after cooling and gasification, record the safe shutdown time, record the data changes of the first temperature sensor 16 and the first pressure sensor 15. Through the detected temperature and pressure data, the phase state in the main pipeline 13 except for the visible pipe section 20 can be calculated inversely, and then the shutdown behavior of the supercritical carbon dioxide pipeline under the set working conditions can be simulated and tested. The safe shutdown time of the main pipeline 13 without damage can be accurately understood. The temperature in the storage tank 6 and the main pipeline 13 can be adjusted through the temperature control module, so as to simulate the shutdown behavior under different working conditions. For the leak test, when the temperature and pressure in the storage tank 6 and the pipeline reach the requirements of the experimental working conditions, open the first valve 12 and the second valve 25, and record the leak time. Carbon dioxide quickly enters the leak test pipeline 27, and the rupture disk breaks under the action of the pressure difference inside and outside the pipe section. Record the data of the first temperature sensor 16, the first pressure sensor 15, the fiber optic temperature sensor, and the carbon dioxide concentration sensor 23, and then simulate and test the leak behavior of the supercritical carbon dioxide pipeline under different working conditions. Thus, relevant data and safety guarantees are provided for the actual project.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the protection scope of the technical solutions of the embodiments of the present invention.

Claims

1. A supercritical carbon dioxide pipeline flow assurance experimental test system, characterized in that, It includes a stop-transmission test module, a carbon dioxide supply module and a control module. The stop-transmission test module includes a trunk pipeline, a high-speed camera and a visible pipe section. The carbon dioxide supply module is connected to one end of the trunk pipeline for conveying required carbon dioxide into the trunk pipeline. The visible pipe section is installed on the trunk pipeline. A first valve is installed at the starting end of the trunk pipeline, and a second valve is installed at the terminal end of the trunk pipeline. The high-speed camera is arranged directly above the visible pipe section, and the high-speed camera, the first valve and the second valve are all connected to the control module.

2. The supercritical carbon dioxide pipeline flow assurance experimental test system according to claim 1, wherein The critical carbon dioxide pipeline flow assurance experimental test system also includes a temperature control module, which is configured to change the initial state of the carbon dioxide in the trunk pipeline and the carbon dioxide delivered to the trunk pipeline by the carbon dioxide supply module through temperature control.

3. The supercritical carbon dioxide pipeline flow assurance experimental test system according to claim 2, characterized in that, The carbon dioxide supply module includes a storage tank and a carbon dioxide tanker truck, wherein the gas phase outlet of the carbon dioxide tanker truck is connected to the gas inlet of the storage tank, and the liquid phase outlet of the carbon dioxide tanker truck is connected to the liquid inlet of the storage tank.

4. The supercritical carbon dioxide pipeline flow assurance experimental test system according to claim 3, wherein The temperature control module includes a temperature control box, a first heating pipe belt and a second heating pipe belt, the first heating pipe belt is wound around the trunk pipeline, the second heating pipe belt is wound around the outer wall of the storage tank, and the first heating pipe belt and the second heating pipe belt are both connected to the temperature control box.

5. The supercritical carbon dioxide pipeline flow assurance experimental test system according to claim 1, characterized in that, A plurality of first pressure sensors and a plurality of first temperature sensors are installed on the trunk pipeline along its length direction, and both the first pressure sensors and the first temperature sensors are communicatively connected with the control module.

6. The supercritical carbon dioxide pipeline flow assurance experimental test system according to claim 3, wherein The storage tank is equipped with a pressure gauge and a second temperature sensor. The storage tank is provided with a safety outlet, and a safety valve is installed on the safety outlet.

7. The supercritical carbon dioxide pipeline flow assurance experimental test system according to any one of claims 3-6, characterized in that, The supercritical carbon dioxide pipeline flow assurance experimental test system also includes a leakage test module, which includes a leakage test pipe, a test box and an optical fiber rack. The top of the test box is an open structure, and the test box is filled with soil. A plurality of air outlets are arranged on the outer wall of the test box. One end of the leakage test pipe is connected to the trunk pipeline, and the other end of the leakage test pipe extends into the test box and is in a closed state. A leakage hole is arranged on the leakage test pipe in the test box, and a bursting disc is installed in the leakage hole. The optical fiber rack is pre-buried in the test box, and an optical fiber temperature sensor is installed on the optical fiber rack.

8. The supercritical carbon dioxide pipeline flow assurance experimental test system according to claim 7, characterized in that, A plurality of carbon dioxide concentration sensors are placed on the top of the test box, and a high-definition camera is arranged above the test box. Both the carbon dioxide concentration sensor and the high-definition camera are communicatively connected with the control module.

9. A shutdown experiment test method carried out based on the supercritical carbon dioxide pipeline flow assurance experimental test system according to any one of claims 2-8, characterized in that, The following steps are involved: The control module controls the first valve to open and the second valve to close, and the carbon dioxide supply module is used to fill the trunk pipeline with liquid carbon dioxide until the trunk pipeline is full; Using a temperature control module to increase the temperature of the trunk pipeline and obtain temperature and pressure information in the trunk pipeline; Use the control module to determine the size of the temperature value and the pressure value and the corresponding experimental working condition required value; If both the temperature value and the pressure value are equal to the corresponding experimental condition requirement values, the temperature control module is used to keep the temperature and pressure values unchanged and stay still for the first set time; After reaching the first set time, a shutdown experiment test is carried out, which specifically includes: closing the first valve through the control module, controlling the main pipeline to be at the expected ambient temperature through the temperature control module, so that the carbon dioxide in the main pipeline undergoes natural temperature drop, using a high-speed camera to photograph the inside of the visible pipe section during the natural temperature drop, and recording the pressure and temperature values of the carbon dioxide in the main pipeline in real time until the temperature in the main pipeline drops to the expected ambient temperature.

10. A leakage experiment test method carried out based on the supercritical carbon dioxide pipeline flow assurance experimental test system described in any one of claims 7-8, characterized in that, The leakage experiment test method includes the following steps: The control module is used to control the first valve to open and the second valve to close, and a tanker is used to fill the storage tank and the main pipeline with liquid carbon dioxide until it is full; The temperature control module is used to heat up the storage tank and the main pipeline and obtain the temperature and pressure information in the storage tank and the main pipeline; The control module is used to judge the magnitudes of the temperature values and pressure values in the storage tank and the main pipeline and the corresponding experimental condition requirement values; If both the temperature value and the pressure value in the storage tank and the main pipeline are equal to the corresponding experimental condition requirement values, the temperature control module is used to keep the temperature and pressure values unchanged and stay still for the first set time; After reaching the first set time, a leakage test experiment is carried out, which specifically includes: The control module is used to open the second valve and start timing, and the carbon dioxide leaks out from the leakage hole; During the leakage process, the temperature value in the test box and the carbon dioxide concentration value on the surface of the test box are obtained in real time; the visible cloud during the leakage process and the characteristics of the soil surface in the test box are obtained through a high-definition camera; When the pressure value in the obtained main pipeline drops to the normal temperature pressure, it is determined that the leakage is complete, the control module is used to control the first valve and the second valve to close, and the timing ends.

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