Buried carbon dioxide pipeline leakage diffusion experiment device and method

Abstract

The invention belongs to the technical field of pipeline conveying, and particularly relates to a carbon dioxide pipeline leakage diffusion experiment device and method. The carbon dioxide pipeline leakage diffusion experiment device comprises a gas supply boosting mechanism used for providing carbon dioxide and boosting the pressure of the carbon dioxide to be larger than a preset pressure value; the pressure reducing valve is arranged at an outlet of the air supply boosting mechanism and is used for controlling the emission pressure of the carbon dioxide; the water bath mechanism is arranged at an outlet of the pressure reducing valve, and two branches are arranged at the tail end of the water bath mechanism and are respectively a soil end discharge outlet and an atmosphere end discharge outlet; the soil end discharge port is connected with the bottom of the soil box, and the caliber of the atmosphere end discharge port is adjusted according to the mass discharge flow of the soil end discharge port, so that the atmosphere end discharge port is equivalent to the soil end discharge port connected with the soil box. The device can simulate the process that carbon dioxide is released to soil under the stable pressure condition.

Description

Technical Field

[0001] This invention belongs to the field of pipeline transportation technology, specifically relating to an experimental device for the leakage and diffusion of buried carbon dioxide pipelines and an experimental method for the leakage and diffusion of carbon dioxide pipelines. Background Technology

[0003] Carbon capture and storage (CCUS) technology has received increasing attention in recent years as a feasible method to reduce excess carbon dioxide concentration in the atmosphere. CCUS technology consists of three processes: carbon capture, carbon utilization, and carbon storage. Carbon dioxide transportation, as a key link in CCUS technology, plays a connecting role in the CCUS technology chain. Most long-distance carbon dioxide pipelines are buried underground. Due to the corrosion of underground soil, buried pipelines are prone to small-hole leaks. Because the pipelines are relatively long, the pressure change under small-hole leak conditions is relatively small, and can even be considered as constant pressure release. Therefore, conducting experimental research on the diffusion of small-hole leaks in buried carbon dioxide pipelines based on the constant pressure release scenario is of significant reference and application value for studying temperature changes near the leak point and the diffusion law of CO2 gas in shallow soil, and for developing key technologies such as carbon dioxide pipeline leak monitoring and early warning, personnel evacuation, and risk assessment. Summary of the Invention

[0004] To address the technical problems described above, this invention aims to provide a carbon dioxide pipeline leakage diffusion experimental device that can simulate the process of carbon dioxide being released into the soil under stable pressure conditions.

[0005] This invention also proposes an experimental method for carbon dioxide pipeline leakage and diffusion, which can simulate the leakage and diffusion of carbon dioxide pipelines.

[0006] According to the present invention, a carbon dioxide pipeline leakage diffusion experimental apparatus is provided, comprising:

[0007] The gas supply booster mechanism is used to supply carbon dioxide and boost its pressure to a value greater than a preset pressure.

[0008] A pressure reducing valve is installed at the outlet of the gas supply and pressure boosting mechanism to control the emission pressure of carbon dioxide.

[0009] A water bath mechanism is located at the outlet of the pressure reducing valve, and two branches are provided at the end of the water bath mechanism, namely a soil discharge port and an atmospheric discharge port.

[0010] A soil tank, wherein the soil end discharge port is connected to the bottom of the soil tank, and the diameter of the atmospheric end discharge port is adjusted according to the mass discharge flow rate of the soil end discharge port, so that the atmospheric end discharge port is equivalent to the soil end discharge port connected to the soil tank.

[0011] In a preferred embodiment, a temperature sensor is provided on the lower side of the soil tank, and a carbon dioxide sensor is provided on the upper side of the soil tank.

[0012] In a preferred embodiment, a plurality of the carbon dioxide sensors are arranged sequentially in a horizontal direction inside the soil tank, with the line of the carbon dioxide sensors located directly above the soil end discharge port, and the soil tank is made of a transparent material.

[0013] In a preferred embodiment, a sensor mounting frame is also included, on which the temperature sensor and the carbon dioxide sensor are mounted.

[0014] In a preferred embodiment, the gas supply and pressurization mechanism includes a gas storage cylinder, a pressurization pump, and a buffer tank connected in sequence.

[0015] In a preferred embodiment, a temperature control zone is provided between the pressurization pump and the buffer tank.

[0016] In a preferred embodiment, the water bath mechanism includes a water bath tank, a circulating pump, and a cold water tank connected in a closed loop in sequence, wherein the water bath tank heats the carbon dioxide flowing out of the pressure reducing valve.

[0017] In a preferred embodiment, the process for determining the mass discharge flow rate of the soil end discharge port is as follows:

[0018] The Fluent simulation software was selected, and the preset pressure value and the actual monitored temperature value were used as initial conditions. A suitable equation of state and turbulence model were selected. The porosity, particle diameter and permeability of the soil medium in the soil tank were experimentally detected, and the viscous resistance and inertial resistance coefficients of the soil were calculated according to the Ergun formula. The soil permeability, soil porosity, soil viscous resistance and inertial resistance were input into the Fluent simulation software. The software was run and the mass discharge flow rate at the inlet was monitored. The mass discharge flow rate after stabilization is the mass discharge flow rate at the soil end discharge port.

[0019] In a preferred embodiment, the appropriate state equation is selected as the PR equation.

[0020] In a preferred embodiment, the turbulence model is a k-epsilon or k-omega model.

[0021] In a preferred embodiment, the carbon dioxide sensor is provided with an encapsulation shell, the bottom of which is open and provided with a polymer breathable membrane.

[0022] According to the present invention, a method for testing the diffusion of carbon dioxide pipeline leakage is also provided, using the carbon dioxide pipeline leakage diffusion testing apparatus provided according to the present invention, comprising the following steps:

[0023] The carbon dioxide is pressurized to a pressure greater than the preset value using a gas supply booster mechanism.

[0024] Close the soil discharge port and open the pressure reducing valve, water bath mechanism and atmospheric discharge port;

[0025] After the flow rate at the atmospheric discharge port stabilizes, close the atmospheric discharge port and open the soil discharge port to conduct the experiment.

[0026] Compared with the prior art, the advantages of this application are as follows.

[0027] This invention can regulate the pressure of carbon dioxide by controlling the flow rate of the pressurizing pump, the temperature of the temperature control belt, and the temperature of the water bath mechanism.

[0028] This invention uses a soil box made of transparent material to fill with soil, which enables visual observation of the effect of gas on the soil during the experiment.

[0029] This invention features an atmospheric discharge port, which ensures that the fluid is released at the soil discharge port when it reaches a stable set state. This avoids the need to frequently replace the soil in the soil tank due to the pressure of carbon dioxide discharged from the soil end not meeting the set conditions in the early stages of the experiment.

[0030] This invention provides an arrangement for temperature and carbon dioxide sensors that reduces the number of sensors required. The carbon dioxide sensor is encapsulated in a perforated plastic shell, with a breathable polymer film adhered to the shell to prevent adverse effects from soil on the sensor. Attached Figure Description

[0031] The present invention will now be described with reference to the accompanying drawings.

[0032] Figure 1 A schematic diagram of an embodiment of a carbon dioxide pipeline leakage diffusion experimental apparatus according to the present invention is shown.

[0033] Figure 2 A schematic diagram of one embodiment of the sensor mounting frame of the present invention.

[0034] In the picture:

[0035] 1. Gas supply and pressure boosting mechanism; 11. Gas storage cylinder; 12. Pressure pump; 13. Buffer tank; 14. Temperature control band; 15. Safety valve;

[0036] 2. Pressure reducing valve;

[0037] 3. Water bath mechanism; 31. Water bath tank; 32. Circulating pump; 33. Cold water tank;

[0038] 4. Soil discharge port; 41. First valve;

[0039] 5. Atmospheric exhaust port; 51. Second valve;

[0040] 6. Soil tank;

[0041] 7. Temperature sensor;

[0042] 8. Carbon dioxide sensor;

[0043] 9. Data logger;

[0044] 10. Sensor mounting frame; 101. Mounting plate;

[0045] 100. Experimental apparatus for leakage and diffusion of buried carbon dioxide pipelines.

[0046] In this application, all drawings are schematic and are used only to illustrate the principles of the invention, and are not drawn to scale. Detailed Implementation

[0047] The invention will now be described with reference to the accompanying drawings.

[0048] It should be noted that in this application, the direction of carbon dioxide according to the present invention is described as "before" or similar terms, while the direction of carbon dioxide is described as "after" or similar terms.

[0049] Figure 1 The structure of the buried carbon dioxide pipeline leakage diffusion experimental apparatus 100 according to the present invention is shown. Figure 1 As shown, the buried carbon dioxide pipeline leakage diffusion experimental device 100 includes a gas supply and pressure boosting mechanism 1, a pressure reducing valve 2, a water bath mechanism 3, and a soil tank 6 connected in sequence from front to back.

[0050] The gas supply and pressurization mechanism 1 is located at the front end of the buried carbon dioxide pipeline leakage diffusion experimental device 100. It is used to supply carbon dioxide for the experimental process and pressurize the carbon dioxide to a value greater than the preset pressure. The preset pressure value can be set with reference to the pipeline pressure in the carbon dioxide delivery pipeline in the prior art.

[0051] Pressure reducing valve 2 is installed at the outlet of gas supply boosting mechanism 1 to control the emission pressure of carbon dioxide and keep the carbon dioxide emitted from gas supply boosting mechanism 1 within a certain pressure range.

[0052] The water bath mechanism 3 is located at the outlet of the pressure reducing valve 2. Two branches are located at the end of the water bath mechanism 3: a soil discharge port 4 and an atmospheric discharge port 5. The water bath mechanism 3 can further control the temperature of the carbon dioxide discharged from the pressure reducing valve 2, thereby achieving precise pressure regulation of the carbon dioxide.

[0053] In this setup, the gas supply boosting mechanism 1, the pressure reducing valve 2, and the water bath mechanism 3 are dynamically adjusted in real time, so that carbon dioxide can be discharged from the soil end discharge port 4 under stable pressure.

[0054] The soil end discharge port 4 is connected to the bottom of the soil tank 6, and the diameter of the atmospheric end discharge port 5 is set according to the mass discharge flow rate of the soil end discharge port 4, so that the atmospheric end discharge port 5 is equivalent to the soil end discharge port 4 connected to the soil tank 6.

[0055] At the initial stage of the experiment, the soil exhaust port 4 was first closed, and the atmospheric exhaust port 5 was opened. After the pressure output from the atmospheric exhaust port 5 stabilized, the atmospheric exhaust port 5 was then closed, and the soil exhaust port 4 was opened simultaneously to conduct the experiment. This method avoids the instability of carbon dioxide pressure in the early stages of the experiment, which could affect the accuracy of the experiment.

[0056] A temperature sensor 7 is installed on the lower side of the soil tank 6, and a carbon dioxide sensor 8 is installed on the upper side of the soil tank 6.

[0057] Specifically, multiple temperature sensors 7 are arranged in a matrix on the lower side of the soil tank 6, and all of the temperature sensors 7 are set on the same vertical plane, which passes through the soil end discharge port 4. In this embodiment, the multiple temperature sensors 7 are arranged in three rows and seven columns, close to the bottom of the soil tank 6. Preferably, several other temperature sensors 7 are also provided, arranged sequentially along the vertical direction, and set directly above the soil end discharge port 4.

[0058] Multiple carbon dioxide sensors 8 are arranged horizontally within the soil tank 6, with the line of the carbon dioxide sensors 8 positioned directly above the soil end discharge port 4. In a preferred embodiment, the multiple carbon dioxide sensors 8 are arranged in a matrix on the upper side of the interior of the soil tank 6. Figure 1 As shown, in this embodiment, a four-row, five-column carbon dioxide sensor 8 is arranged on the upper side inside the soil tank 6, and multiple carbon dioxide sensors 8 and multiple temperature sensors 7 are all located on the same vertical plane.

[0059] Temperature sensor 7 and carbon dioxide sensor 8 are both connected to data logger 9, which can record the data changes of temperature sensor 7 and carbon dioxide sensor 8 in real time. Data logger 9 is prior art and not a key feature of this invention, so it will not be described in detail here.

[0060] It should be noted that the number of carbon dioxide sensors 8 and temperature sensors 7 is not limited to the present invention, and the specific number can be adjusted according to the actual situation.

[0061] In a preferred embodiment, the soil tank 6 is made of a transparent material, specifically, it may be made of transparent plexiglass.

[0062] Temperature sensor 7 and carbon dioxide sensor 8 need to be buried in the soil for monitoring. During the soil burial and compaction process, their positions inevitably shift, which will affect subsequent experimental analysis. Therefore, in a preferred embodiment, the buried carbon dioxide pipeline leakage diffusion experimental device 100 also includes a sensor fixing frame 10 for mounting temperature sensor 7 and carbon dioxide sensor 8. Figure 2 As shown, the sensor fixing frame 10 includes multiple fixing plates 101 arranged laterally and longitudinally. In this embodiment, the fixing plates 101 are made of plexiglass. After the sensor fixing frame 10 is buried in the soil tank 6, its uppermost fixing plate 101 is located above the soil layer. The width of the fixing plate 101 is as close as possible to the diameter of the sensor. Preferably, the width of the fixing plate 101 is equal to the diameter of the sensor. This arrangement helps to maintain the distribution of the flow field in the soil as much as possible, ensuring the accuracy of the test results. Multiple mounting holes for installing the carbon dioxide sensor 8 and the temperature sensor 9 are evenly arranged on the fixing plate 101, and the number of mounting holes is as close as possible. This facilitates adjustment of the sensor placement and number, and minimizes the disruption of the soil flow field by the sensor fixing frame 10. The specific position and number of the temperature sensor 7 and the carbon dioxide sensor 8 can be designed according to the specific experimental requirements. The scope of protection of this invention is not limited to what is given in this application. Figure 1 The diagram shows an arrangement of temperature sensor 7 and carbon dioxide sensor 8. The sensor mounting frame 10 is primarily designed for monitoring the temperature and carbon dioxide concentration distribution in the vertical direction of the leak.

[0063] In one specific embodiment, the gas supply and pressurization mechanism 1 includes a gas storage cylinder 11, a pressurization pump 12, and a buffer tank 13 connected in sequence.

[0064] The gas cylinder 11 is located at the front end and is used to supply carbon dioxide. The pressurizing pump 12 and the buffer tank 13 are connected to the gas cylinder 11 in sequence. The pressurizing pump 12 can pump the carbon dioxide in the gas cylinder 11 into the buffer tank 13 and pressurize it so that the carbon dioxide pressure in the buffer tank 13 is higher than the preset pressure value.

[0065] In a preferred embodiment, a temperature control strip 14 is provided between the pressurization pump 12 and the buffer tank 13. The temperature control strip 14 is installed on the pipeline between the pressurization pump 12 and the buffer tank 13. In this embodiment, the temperature control strip 14 is an electric heating tape, which covers the pipeline between the pressurization pump 12 and the buffer tank 13. The temperature control strip 14 can heat the carbon dioxide, thereby increasing the pressure of the carbon dioxide in the buffer tank 13.

[0066] In this embodiment, the water bath mechanism 3 includes a water bath tank 31, a circulation pump 32, and a cold water tank 33 connected in a closed loop. The water bath tank 31 heats the carbon dioxide flowing out of the pressure reducing valve 2. When the temperature in the water bath tank 31 is too high, starting the circulation pump 32 allows the cold water tank 33 to exchange water with the water in the water bath tank 31, thereby lowering the temperature in the water bath tank 31.

[0067] In this embodiment, the diameter of the atmospheric discharge port 5 needs to be adjusted according to the mass discharge flow rate of the soil discharge port 4 to avoid any impact when switching between the soil discharge port 4 and the atmospheric discharge port 5. The process for determining the mass discharge flow rate of the soil discharge port 4 is as follows:

[0068] The Fluent simulation software was selected, and the preset pressure value and the actual monitored temperature value of the soil end discharge port 4 were used as initial conditions. A suitable equation of state and turbulence model were selected; in this embodiment, the PR equation was chosen, and the k-epsilon or k-omega model was selected. The porosity, particle diameter, and permeability of the soil medium in the soil tank 6 were experimentally measured, and the viscous resistance and inertial resistance coefficients of the soil were calculated according to the Ergun formula. The soil permeability, soil porosity, soil viscous resistance, and inertial resistance were input into the Fluent simulation software. The software was run, and the mass discharge flow rate was monitored. The stabilized mass discharge flow rate is the mass discharge flow rate at the soil end discharge port 4. The diameter of the atmospheric end discharge port 5 was adjusted according to the obtained mass discharge flow rate at the soil end discharge port 4, so that the diameter of the atmospheric end discharge port 5 is equivalent to that of the soil end discharge port 4 connected to the soil tank 6.

[0069] In a preferred embodiment, a safety valve 15 is provided on the buffer tank 13. The safety valve 15 is used to prevent damage caused by excessive internal pressure in the buffer tank 13.

[0070] In one embodiment of the present invention, a method for experimentally measuring the leakage and diffusion of carbon dioxide in a pipeline is provided, using the experimental apparatus for experimentally measuring the leakage and diffusion of carbon dioxide in a pipeline provided according to the present invention, comprising the following steps:

[0071] The carbon dioxide is pressurized to a pressure value greater than the preset pressure value using the gas supply booster mechanism 1;

[0072] Close the soil end discharge port 4, and open the pressure reducing valve 2, water bath mechanism 3 and atmospheric end discharge port 5;

[0073] After the flow rate at atmospheric outlet 5 stabilizes, close atmospheric outlet 5 and open soil outlet 4 to conduct the experiment.

[0074] In this embodiment, the gas storage cylinder 11 contains liquid carbon dioxide, which is pumped into the buffer tank 13 by the pressurization pump 12. The temperature control band 14 between the pressurization pump 12 and the buffer tank 13 can increase the pressure. When the pressure in the buffer tank 13 is greater than the preset pressure value, the pressure reducing valve 2 is opened to control the pressure of the discharged carbon dioxide to close to the preset pressure value. There is a friction loss along the way when the carbon dioxide flows from the pressure reducing valve 2 to the soil end discharge port 4. After being heated and pressurized by a water bath 31, the pressure at the soil end discharge port 4 is stabilized at the predetermined pressure value.

[0075] The atmospheric discharge port 5 of this invention can be used to regulate and stabilize the test pressure. A first valve 41 is provided at the soil discharge port 4, and a second valve 51 is provided at the atmospheric discharge port 5. In the initial stage of the experiment, before the pressure stabilizes to the preset pressure value, the first valve 41 at the soil discharge port 4 remains closed, and the second valve 51 at the atmospheric discharge port 5 remains open.

[0076] The constant pressure control process is as follows.

[0077] When the fluid in the buffer tank 13 reaches a certain level, the pressure reducing valve 2 is opened to reduce the pressure to the preset value. When the pressure at the atmospheric discharge port 5 is lower than the preset pressure value, the water bath 31 is opened for heating until the pressure at the atmospheric discharge port 5 reaches the preset pressure value. When the pressure at the atmospheric discharge port 5 is too high, the circulation pump 32 is turned on to replenish cold water in the water bath 31, while some hot water flows out of the water bath 31, causing the water temperature to drop and achieving the purpose of pressure reduction. After the pressure at the atmospheric discharge port 5 reaches the set operating pressure and stabilizes, the second valve 51 at the atmospheric discharge port 5 is closed, and the first valve 41 at the soil discharge port 4 is opened, thus starting the experiment and monitoring the temperature and carbon dioxide concentration changes at the soil discharge port 4.

[0078] To ensure that the carbon dioxide outlet pressure at the soil outlet 4 is the same as the outlet pressure at the atmospheric outlet 5 when the atmospheric outlet 5 is closed, this embodiment simulates the mass discharge flow rate at the soil outlet 4, and then adjusts the diameter of the atmospheric outlet 5 based on this, until the atmospheric outlet 5 has the same mass discharge flow rate as the soil outlet 4.

[0079] According to a specific embodiment of the present invention, it is necessary to keep the carbon dioxide phase unchanged during the experiment.

[0080] Phase control process of carbon dioxide: The phase of carbon dioxide is mainly controlled by temperature control band 14. Taking the experimental condition as the supercritical phase as an example, carbon dioxide is heated by temperature control band 14, and the pressure at pressure reducing valve 2 is controlled to be at least 7.8 MPa. When the temperature of the fluid after being heated by water bath 31 is still less than 31.1 degrees Celsius, the power of temperature control band 14 is adjusted and increased. When the temperature is greater than 31.1 degrees Celsius, the power increase is stopped, and the power of temperature control band 14 is kept constant.

[0081] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0082] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0083] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0084] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An experimental apparatus for the leakage and diffusion of buried carbon dioxide pipelines, characterized in that, include: Gas supply boosting mechanism (1) is used to supply carbon dioxide and boost the carbon dioxide pressure to a value greater than a preset pressure. A pressure reducing valve (2) is installed at the outlet of the gas supply boosting mechanism (1) to control the emission pressure of carbon dioxide; A water bath mechanism (3) is provided at the outlet of the pressure reducing valve (2). Two branches are provided at the end of the water bath mechanism (3), namely a soil end discharge port (4) and an atmospheric end discharge port (5). Soil tank (6), the soil end discharge port (4) is connected to the bottom of the soil tank (6), and the diameter of the atmospheric end discharge port (5) is adjusted according to the mass discharge flow rate of the soil end discharge port (4) so ​​that the atmospheric end discharge port (5) is equivalent to the soil end discharge port (4) connected to the soil tank (6).

2. The experimental apparatus for leakage and diffusion of buried carbon dioxide pipelines according to claim 1, characterized in that, A temperature sensor (7) is installed on the lower side inside the soil tank (6), and a carbon dioxide sensor (8) is installed on the upper side inside the soil tank (6).

3. The experimental apparatus for leakage and diffusion of buried carbon dioxide pipelines according to claim 2, characterized in that, Multiple carbon dioxide sensors (8) are arranged in sequence in the soil tank (6) in a horizontal direction. The line where the carbon dioxide sensors (8) are located is directly above the soil end discharge port (4). The soil tank (6) is made of transparent material.

4. The experimental apparatus for leakage and diffusion of buried carbon dioxide pipelines according to claim 3, characterized in that, It also includes a sensor mounting frame (10), on which the temperature sensor (7) and the carbon dioxide sensor (8) are mounted.

5. The experimental apparatus for leakage and diffusion of buried carbon dioxide pipelines according to any one of claims 1 to 4, characterized in that, The gas supply and pressure boosting mechanism (1) includes a gas storage cylinder (11), a pressure pump (12) and a buffer tank (13) connected in sequence, and a temperature control band (14) is provided between the pressure pump (12) and the buffer tank (13).

6. The experimental apparatus for leakage and diffusion of buried carbon dioxide pipelines according to any one of claims 1 to 3, characterized in that, The water bath mechanism (3) includes a water bath tank (31), a circulating pump (32) and a cold water tank (33) connected in a closed loop in sequence. The water bath tank (31) heats the carbon dioxide flowing out of the pressure reducing valve (2).

7. The experimental apparatus for leakage and diffusion of buried carbon dioxide pipelines according to any one of claims 1 to 3, characterized in that, The process for determining the mass discharge flow rate of the soil end discharge port (4) is as follows: The Fluent simulation software was selected, and the preset pressure value and the actual monitored temperature value were used as initial conditions. A suitable equation of state and turbulence model were selected. The porosity, particle diameter and permeability of the soil medium in the soil tank (6) were experimentally detected, and the viscous resistance and inertial resistance coefficients of the soil were calculated according to the Ergun formula. The soil permeability, soil porosity, soil viscous resistance and inertial resistance were input into the Fluent simulation software. The software was run and the mass discharge flow rate at the inlet was monitored. The mass discharge flow rate after stabilization was the mass discharge flow rate at the soil end discharge port (4).

8. The experimental apparatus for leakage and diffusion of buried carbon dioxide pipelines according to claim 7, characterized in that, Choose the appropriate equation of state as the PR equation.

9. The experimental apparatus for leakage and diffusion of buried carbon dioxide pipelines according to claim 7, characterized in that, The turbulence model is either the k-epsilon or the k-omega model.

10. A method for experimental diffusion of carbon dioxide leakage in a pipeline, characterized in that, The carbon dioxide pipeline leakage diffusion experimental apparatus according to any one of claims 1 to 9 comprises the following steps: The carbon dioxide is pressurized to a value greater than the preset pressure using the gas supply booster mechanism (1); Close the soil end discharge port (4), and open the pressure reducing valve (2), water bath mechanism (3) and atmospheric end discharge port (5); After the flow rate of the atmospheric discharge port (5) stabilizes, the atmospheric discharge port (5) is closed and the soil discharge port (4) is opened to conduct the experiment.

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