Dense-phase supercritical CO2 leakage diffusion similar model experiment system and experiment method

Abstract

The invention relates to a dense-phase supercritical CO2 leakage diffusion similar model experiment system and method, and the system comprises a gas supply system which is used for providing a CO2 leakage gas source in an experiment; the air supply system is used for providing environment air and measuring the average air speed; a reaction system and a heating system, the reaction system is connected with the gas supply system, and the reaction system is used for enabling a CO2 leakage gas source to react under the heating of the heating system to form supercritical CO2; the leakage system is connected with the reaction system and is used for leaking and releasing supercritical CO2; and the data acquisition system is arranged at the tail end of the leakage system and is used for acquiring temperature and concentration data of the released supercritical CO2. According to the method, the size of the offshore platform and the CO2 leakage key parameters can be synchronously and reasonably scaled, so that the method meets indoor development conditions in the aspects of operability, safety and the like, meanwhile, an experimental result is not distorted, and errors are within an acceptable range.

Description

Technical Field

[0001] The invention relates to the technical field of offshore CCS / CCUS engineering, and in particular to a dense phase supercritical CO2 leakage diffusion similarity model experimental system and an experimental method. Background Art

[0002] At present, injecting dense supercritical CO2 into the seabed saline layer through an offshore platform for storage is a relatively economical and efficient way. The CO2 injected through the offshore platform is in a supercritical state, with the characteristics of high pressure and high purity. After the supercritical CO2 leaks, it will change from the supercritical state to the saturated gas state in the space inside the leak, forming a high-pressure gas at the leak and releasing it. High concentrations of CO2 are extremely dangerous and can cause suffocation and death of operators.

[0003] In response to this situation, CO2 leakage and diffusion research is generally carried out to understand the CO2 concentration distribution characteristics under typical working conditions, clarify the CO2 dangerous concentration range, determine the safe range and distance for workers, and provide a basis for CO2 monitoring and probe layout plans.

[0004] At present, mathematical models, numerical simulations and experimental simulations are mainly used to study the leakage and diffusion of CO2. Mathematical models have good theoretical properties, but the calculation process is complex and the amount of calculation is large. The influence of obstacles on diffusion cannot be considered. Therefore, the calculated CO2 concentration is quite different from the actual concentration. The numerical simulation method has good economy and repeatability. At the same time, it can restore the leakage scene 1:1 through geometric modeling, and has good authenticity. However, the disadvantage is that it requires a large number of parameter settings and requires high quality of simulation personnel. In addition, its major disadvantage is the lack of experimental comparison and verification. The experimental method is the most realistic way to reflect the leakage and diffusion of CO2. However, it is very difficult to carry out the leakage and diffusion experiment of supercritical CO2 at the original scale. First, it is necessary to build a physical model of the offshore platform, and at the same time, it is necessary to build CO2 under the same working conditions and state. There are great safety hazards in the experimental process, and the operability and repeatability are very poor. It is time-consuming and laborious to complete the entire experiment.

[0005] Therefore, there is an urgent need for a dense phase supercritical CO2 leakage and diffusion similarity model experimental system and experimental method that can improve the original scale experiment. Summary of the invention

[0006] In view of the above problems, the purpose of the present invention is to provide a dense phase supercritical CO2 leakage and diffusion similarity model experimental system and experimental method, which can synchronously and reasonably scale the offshore platform size and key parameters of CO2 leakage, so that it can meet the conditions for indoor operation in terms of operability and safety, while the experimental results are not distorted and the error is within an acceptable range.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] The dense phase supercritical CO2 leakage and diffusion similarity model experimental system of the present invention comprises:

[0009] Gas supply system, used to provide CO2 leakage gas source in the experiment;

[0010] Air supply system, used to provide ambient wind speed and measure average wind speed;

[0011] A reaction system and a heating system, wherein the reaction system is connected to the gas supply system, and the reaction system is used to react the CO2 leaked gas source into supercritical CO2 under the heating of the heating system;

[0012] A leakage system, connected to the reaction system, for leaking and releasing supercritical CO2;

[0013] The data acquisition system is arranged at the tail end of the leakage system and is used to collect the temperature and concentration data of the released supercritical CO2.

[0014] The dense phase supercritical CO2 leakage and diffusion similarity model experimental system, preferably, the gas supply system includes: a liquid CO2 Dewar flask and a liquid CO2 pump; the liquid CO2 Dewar flask and the liquid CO2 pump are connected by a first pipeline; a liquid outlet valve is provided on the first pipeline; the outlet of the liquid CO2 pump is used to be connected to the storage tank of the reaction system through a second pipeline; the outlet of the liquid CO2 pump is also connected to a first ball valve; and a second ball valve is provided on the second pipeline.

[0015] The dense phase supercritical CO2 leakage and diffusion similarity model experimental system, preferably, the air supply system includes an industrial fan and an anemometer; the industrial fan and the anemometer are respectively arranged on the periphery of the reaction system, the industrial fan is used to provide ambient wind, and the anemometer is used to measure the average wind speed in the environment.

[0016] The dense phase supercritical CO2 leakage and diffusion similarity model experimental system, preferably, the reaction system includes: a storage tank, a pressure gauge and a safety valve; the inlet of the storage tank is used to be connected to the liquid CO2 pump of the gas supply system through a second pipeline; the pressure gauge and the safety valve are respectively plugged into the storage tank; the outlet of the storage tank is used to be connected to the leakage system through a third pipeline; a third ball valve is provided on the third pipeline; and a fourth ball valve is also connected to the bottom of the storage tank.

[0017] The dense phase supercritical CO2 leakage and diffusion similarity model experimental system, preferably, the heating system includes a heating blanket and a heating tape; the two heating blankets are respectively arranged at the two ends of the storage tank, and the heating tape is arranged on the periphery of the third pipeline, and the heating blanket and the heating tape are respectively used to heat the CO2 in the storage tank or in the third pipeline.

[0018] The dense phase supercritical CO2 leakage and diffusion similarity model experimental system, preferably, the leakage system includes a flange, a fourth pipeline and a leakage nozzle; one end of the fourth pipeline is used to connect with the third pipeline of the reaction system; the other end of the fourth pipeline is connected to the leakage nozzle; the fourth pipeline is divided into multiple sections, and the multiple sections of the fourth pipeline are connected by flanges; the fourth pipeline is provided with a fifth ball valve.

[0019] The dense phase supercritical CO2 leakage and diffusion similarity model experimental system, preferably, the data acquisition system includes a data recorder, a concentration sensor and a temperature sensor; the concentration sensor is used to detect the concentration of CO2 ejected from the leakage nozzle; the temperature sensor is used to detect the temperature of CO2 ejected from the leakage nozzle; the data recorder is used to record the concentration and temperature of CO2 ejected from the leakage nozzle.

[0020] The experimental method of the dense phase supercritical CO2 leakage and diffusion similarity model experimental system of the present invention comprises the following steps:

[0021] Scale down the set offshore platform;

[0022] Based on the scaled-down processing of the assumed offshore platform, the key parameters in the experiment are determined;

[0023] Based on the key parameters in the experiment, a dense phase supercritical CO2 leakage and diffusion experiment was carried out according to the experimental system.

[0024] The experimental method, preferably, the scaling down of the set offshore platform specifically comprises the following steps:

[0025] Assume the actual length of the offshore platform deck is L, the width is D, the height is H, and the inner diameter of the leaking pipe is E;

[0026] Based on the processing cost, site size and experimental operation, the geometric model of the offshore platform is converted into a geometric model with a scale of 1:n. 2 To scale,

[0027]

[0028] Where: subscripts δ1 and δ2 represent the geometric dimensions of the model and prototype respectively; is the similarity ratio;

[0029] The length l, width d, height h of the offshore platform model in the experiment, and the inner diameter e of the pipeline are calculated according to the similarity ratio.

[0030] The experimental method described above preferably comprises the following specific steps for determining the key parameters in the experiment:

[0031] Assuming the instantaneous leakage mass flow rate of CO2 at a certain point in the pipeline is Q, under the influence of the ambient wind speed v, the change of the CO2 volume fraction C at the distance s from the leakage port after time t is:

[0032]

[0033] Where: x, y, z are dimensional indices;

[0034] Based on similarity theory, the dimensional analysis of formula (2) can be transformed into:

[0035]

[0036] Where: π1 is a dimensionless quantity; L is the length dimension, T is the time dimension; M is the mass dimension;

[0037] According to the principle of dimensional homogeneity, we can get from formula (3):

[0038]

[0039] Solving the system of equations, we get x=0, y=1, z=-1;

[0040] Therefore, formula (3) can be written as:

[0041]

[0042] Since the geometric ratio is 1:n 2 , the time scale t1:t2 is 1:1. According to the relationship of formula (5), the geometric scale and the time scale, the ratio of the experimental wind speed v1 to the actual wind speed v2 is calculated to be 1:n 2 The ratio of the experimental leakage aperture e to the actual leakage aperture E is 1:n 2 , the ratio of the experimental leakage pressure to the actual leakage pressure is the square root of the geometric scale, that is, 1:n.

[0043] The experimental method, preferably, the dense phase supercritical CO2 leakage diffusion experiment carried out based on the experimental system specifically includes the following steps:

[0044] (1) Connect the experimental equipment according to the experimental system diagram;

[0045] (2) Place a CO2 concentration sensor at the target location to measure the CO2 concentration and connect it to the data acquisition system;

[0046] (3) Open the liquid outlet valve, the second ball valve, the third ball valve and the fifth ball valve of the liquid CO2 Dewar flask, purge the pipeline and check for leaks;

[0047] (4) Liquid CO2 filling, including:

[0048] a) Close the liquid outlet valve, the first ball valve 1 and the fourth ball valve, and open the second ball valve, the third ball valve and the fifth ball valve;

[0049] b) Open the liquid outlet valve and set the cooling time for the liquid CO2 pump;

[0050] c) After the pump has been cooled, turn on the motor of the liquid CO2 pump, close the fifth ball valve, start the liquid CO2 pump and adjust the speed of the pump to inject the liquid CO2 into the storage tank. When the pressure gauge of the storage tank is greater than 4MPa, close the liquid CO2 pump, the second ball valve and the liquid outlet valve in sequence;

[0051] d) Open the first ball valve to exhaust the CO2 in the pump and the CO2 in the first tube 1;

[0052] (5) Supercritical CO2 preparation, specifically including:

[0053] a) After the filling is completed, the temperature in the tank is lower than the set value, and the heating blanket and heating belt are turned on to heat the reaction system;

[0054] b) monitoring the pressure in the reaction system during the heating process, and when the pressure exceeds the set value, opening the fourth ball valve to release the pressure, and when the pressure drops to the set value, closing the fourth ball valve;

[0055] c) When the pressure in the reaction system exceeds the set value and the temperature exceeds the set value, the supercritical CO2 preparation is completed;

[0056] (6) Install the corresponding leakage nozzle according to the selected leakage diameter and leakage direction, and connect the leakage system to the tube reaction system using the flange;

[0057] (7) Supercritical CO2 leakage experiment, including:

[0058] a) Arrange a camera to record the supercritical CO2 leakage process;

[0059] b) Open the fifth ball valve and start the supercritical CO2 leakage experiment. When the leakage time is reached, close the fifth ball valve and record the concentration and temperature data;

[0060] c) After completing a set of experiments, the pressure and temperature of the reaction system will drop. Continue heating until the pressure reaches the requirements of the next set of experiments and repeat (7).

[0061] The present invention adopts the above technical solution, which has the following advantages:

[0062] (1) Based on the similarity theory, the present invention uses the dimensional analysis method to synchronously and reasonably scale the offshore platform size and key parameters of CO2 leakage, so that the operability and safety of the experiment can be achieved in the indoor environment, while the experimental results are not distorted and the error is within an acceptable range.

[0063] (2) The distribution of CO2 concentration after leakage is determined by key factors such as initial release pressure, ambient wind speed, distance and time. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the following detailed description of the preferred embodiment.The drawings are only for the purpose of illustrating the preferred embodiments and are not to be construed as limiting the invention.

[0065] Throughout the drawings, the same reference numerals are used to denote the same components. In the drawings:

[0066] Figure 1 It is a structural schematic diagram of the dense phase supercritical CO2 leakage and diffusion similarity model experimental system described in the present invention.

[0067] The reference numerals in the figures are as follows:

[0068] 1-Liquid CO2 Dewar flask; 2-Liquid CO2 pump; 3-First pipeline; 4-Liquid outlet valve; 5-Second pipeline; 6-First ball valve; 7-Second ball valve; 8-Storage tank; 9-Pressure gauge; 10-Safety valve; 11-Third pipeline; 12-Third ball valve; 13-Fourth ball valve; 14-Heating blanket; 15-Heating belt; 16-Flange; 17-Fourth pipeline; 18-Leakage nozzle; 19-Fifth ball valve; 20-Data recorder; 21-Concentration sensor; 22-Temperature sensor. DETAILED DESCRIPTION

[0069] The exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0070] The present invention provides a dense phase supercritical CO2 leakage and diffusion similarity model experimental system and experimental method. Based on the similarity theory, the offshore platform size and CO2 leakage key parameters are synchronously and reasonably scaled by using the dimensional analysis method, so that the conditions for indoor operation are achieved in terms of operability and safety, while the experimental results are not distorted and the error is within an acceptable range, thereby realizing the verification of numerical simulation. The present invention is practical, operable and economical, and is suitable for the leakage and diffusion experimental research of heavy gases.

[0071] like Figure 1 As shown, the present invention provides a dense phase supercritical CO2 leakage and diffusion similarity model experimental system, including: a gas supply system, used to provide a CO2 leakage gas source in the experiment; a wind supply system, used to provide an environmental wind speed and measure the environmental average wind speed; a reaction system and a heating system, wherein the reaction system is connected to the gas supply system, and the reaction system is used to react the CO2 leakage gas source into supercritical CO2 under the heating of the heating system; a leakage system, connected to the reaction system, used to leak and release supercritical CO2; a data acquisition system, arranged at the tail end of the leakage system, used to collect temperature and concentration data of the released supercritical CO2.

[0072] In the above embodiment, preferably, the gas supply system includes: a liquid CO2 Dewar flask 1 and a liquid CO2 pump 2; the liquid CO2 Dewar flask 1 and the liquid CO2 pump 2 are connected through a first pipeline 3; a liquid outlet valve 4 is provided on the first pipeline 3; the outlet of the liquid CO2 pump 2 is used to be connected to a storage tank 8 of the reaction system through a second pipeline 5; the outlet of the liquid CO2 pump 2 is also connected to a first ball valve 6; and a second ball valve 7 is provided on the second pipeline 5.

[0073] In the above embodiment, preferably, the air supply system includes an industrial fan and an anemometer (not shown in the figure); the industrial fan and the anemometer are respectively arranged on the periphery of the reaction system, the industrial fan is used to provide ambient wind, and the anemometer is used to measure the average wind speed in the environment.

[0074] In the above embodiment, preferably, the reaction system includes a storage tank 8, a pressure gauge 9 and a safety valve 10; the inlet of the storage tank 8 is used to be connected to the liquid CO2 pump 2 of the gas supply system through the second pipeline 5; the pressure gauge 9 and the safety valve 10 are respectively plugged into the storage tank 8, and the pressure gauge 9 is used to measure the pressure in the storage tank. When the pressure exceeds the set value, the safety valve opens to release the pressure; the outlet of the storage tank 8 is used to be connected to the leakage system through the third pipeline 11; the third pipeline 11 is provided with a third ball valve 12; and the bottom of the storage tank 8 is also connected to a fourth ball valve 13.

[0075] In the above embodiment, preferably, the heating system includes a heating blanket 14 and a heating tape 15; the two heating blankets 14 are respectively arranged at the two ends of the storage tank 8, and the heating tape 15 is arranged on the outer periphery of the third pipeline 11, and the heating blanket 14 and the heating tape 15 are respectively used to heat the CO2 in the storage tank 8 or in the third pipeline 11.

[0076] In the above embodiment, preferably, the leakage system includes a flange 16, a fourth pipe 17 and a leakage nozzle 18; one end of the fourth pipe 17 is used to be connected to the third pipe 11 of the reaction system; the other end of the fourth pipe 17 is connected to the leakage nozzle 18; the fourth pipe 17 is divided into multiple sections, and the multiple sections of the fourth pipe are connected by flanges 16; and a fifth ball valve 19 is provided on the fourth pipe 17.

[0077] In the above embodiment, preferably, the data acquisition system includes a data recorder 20, a concentration sensor 21 and a temperature sensor 22; the concentration sensor 21 is used to detect the concentration of CO2 ejected from the leakage nozzle 18; the temperature sensor 22 is used to detect the temperature of CO2 ejected from the leakage nozzle 18; the data recorder 20 is used to record the concentration and temperature of CO2 ejected from the leakage nozzle 18.

[0078] The present invention also provides a dense phase supercritical CO2 leakage diffusion similarity model experimental method, comprising the following steps:

[0079] S1. Scale down the set offshore platform;

[0080] S2. Determine the key parameters in the experiment based on the scaled-down processing of the set offshore platform;

[0081] S3. Based on the key parameters in the experiment, a supercritical CO2 leakage and diffusion experiment is carried out according to the experimental system.

[0082] In the above embodiment, preferably, the scaling down of the set offshore platform specifically includes the following steps:

[0083] Assume the actual length of the offshore platform deck is L, the width is D, the height is H, and the inner diameter of the leaking pipe is E;

[0084] Based on the processing cost, site size and experimental operation, the geometric model of the offshore platform is converted into a 1:n 2 To scale,

[0085]

[0086] Where: subscripts δ1 and δ2 represent the geometric dimensions of the model and prototype respectively; is the similarity ratio;

[0087] The length l, width d, height h of the offshore platform model in the experiment, and the inner diameter e of the pipeline are calculated according to the similarity ratio.

[0088] In the above embodiment, preferably, the specific steps for determining the key parameters in the experiment are:

[0089] Assume that the instantaneous leakage mass flow rate of CO2 at a certain point in the pipeline is Q. Under the influence of the ambient wind speed v, the change of the CO2 volume fraction C at the leakage port s after time t is: (The above-mentioned parameter variables affecting the change of CO2 volume concentration are Q, v, t, s and C, and the number of parameter variables is p = 5. Among them, the basic dimensions are M, T and L, and the number is q = 3)

[0090]

[0091] Where: x, y, z are dimensional indices;

[0092] Based on similarity theory, the dimensional analysis of formula (2) can be transformed into:

[0093]

[0094] Where: π1 is a dimensionless quantity; L is the length dimension, T is the time dimension; M is the mass dimension;

[0095] According to the principle of dimensional homogeneity, we can get

[0096]

[0097] Solving the system of equations, we get x=0, y=1, z=-1.

[0098] Therefore, formula (2) can be written as:

[0099]

[0100] Since the geometric ratio is 1:n 2 , the time scale t1:t2 is 1:1. According to the relationship of formula (5), the geometric scale and the time scale, the ratio of the experimental wind speed v1 to the actual wind speed v2 is calculated to be 1:n 2 The ratio of the experimental leakage aperture e to the actual leakage aperture E is 1:n 2 , the ratio of the experimental leakage pressure to the actual leakage pressure is the square root of the geometric scale, that is, 1:n.

[0101] In the above embodiment, preferably, the dense phase supercritical CO2 leakage and diffusion experiment carried out according to the experimental system specifically includes the following steps:

[0102] (1) Connect the experimental equipment according to the experimental system diagram;

[0103] (2) Place a CO2 concentration sensor at the target location to measure the CO2 concentration and connect it to the data acquisition system. The power supply voltage of the concentration sensor is 12V;

[0104] (3) Open the liquid outlet valve, the second ball valve, the third ball valve and the fifth ball valve of the liquid CO2 Dewar flask, purge the pipeline and check for leaks;

[0105] (4) Liquid CO2 filling, including:

[0106] a) Close the liquid outlet valve, the first ball valve 1 and the fourth ball valve, and open the second ball valve, the third ball valve and the fifth ball valve;

[0107] b) Open the liquid outlet valve and cool the liquid CO2 pump for 8 to 10 minutes;

[0108] c) After the pump has been cooled, turn on the motor of the liquid CO2 pump, close the fifth ball valve, start the liquid CO2 pump and adjust the speed of the pump to inject the liquid CO2 into the storage tank. When the pressure gauge of the storage tank is greater than 4MPa, close the liquid CO2 pump, the second ball valve and the liquid outlet valve in sequence;

[0109] d) Open the first ball valve to exhaust the CO2 in the pump and the CO2 in the first tube 1;

[0110] (5) Supercritical CO2 preparation, specifically including:

[0111] a) After the filling is completed, the temperature in the tank is lower than -20°C, and the heating blanket and heating belt are turned on to heat the reaction system;

[0112] b) monitoring the pressure in the reaction system during the heating process, and when the pressure exceeds 11 MPa, opening the fourth ball valve to release the pressure, and closing the fourth ball valve when the pressure drops to 9 MPa;

[0113] c) When the pressure in the reaction system exceeds 7.38MPa and the temperature exceeds 31.1°C, supercritical CO2 preparation is completed;

[0114] (6) Install the corresponding leakage nozzle according to the selected leakage diameter and leakage direction, and connect the leakage system to the tube reaction system using the flange;

[0115] (7) Supercritical CO2 leakage experiment, including:

[0116] a) Arrange a camera to record the supercritical CO2 leakage process;

[0117] b) Open the fifth ball valve and start the supercritical CO2 leakage experiment. When the leakage time is reached, close the fifth ball valve and record the concentration and temperature data;

[0118] c) After completing a set of experiments, the pressure and temperature of the reaction system will drop. Continue heating until the pressure reaches the requirements of the next set of experiments and repeat (7).

[0119] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A dense phase supercritical CO2 leakage and diffusion similarity model experimental system, characterized in that: include: Gas supply system, used to provide CO2 leakage gas source in the experiment; Air supply system, used to provide ambient wind and measure the average wind speed; A reaction system and a heating system, wherein the reaction system is connected to the gas supply system, and the reaction system is used to react the CO2 leaked gas source into supercritical CO2 under the heating of the heating system; A leakage system, connected to the reaction system, for leaking and releasing supercritical CO2; The data acquisition system is arranged at the tail end of the leakage system and is used to collect the temperature and concentration data of the released supercritical CO2.

2. The dense phase supercritical CO2 leakage and diffusion similarity model experimental system according to claim 1 is characterized in that: The gas supply system includes: a liquid CO2 Dewar bottle and a liquid CO2 pump; The liquid CO2 Dewar flask and the liquid CO2 pump are connected via a first pipeline; The first pipeline is provided with a liquid outlet valve; The outlet of the liquid CO2 pump is used to be connected to the storage tank of the reaction system through a second pipeline; The outlet of the liquid CO2 pump is also connected to a first ball valve; The second pipeline is provided with a second ball valve.

3. The dense phase supercritical CO2 leakage and diffusion similarity model experimental system according to claim 1 is characterized in that: The air supply system includes an industrial fan and an anemometer; The industrial fan and the anemometer are respectively arranged on the periphery of the reaction system, the industrial fan is used to provide the environmental wind speed, and the anemometer is used to measure the average wind speed in the environment.

4. The dense phase supercritical CO2 leakage and diffusion similarity model experimental system according to claim 1 is characterized in that: The reaction system comprises: a storage tank, a pressure gauge and a safety valve; The inlet of the storage tank is used to be connected to the liquid CO2 pump of the gas supply system through a second pipeline; The pressure gauge and the safety valve are respectively plugged into the storage tank; The outlet of the storage tank is used to be connected to the leakage system through a third pipeline; The third pipeline is provided with a third ball valve; The bottom of the storage tank is also connected to a fourth ball valve.

5. The dense phase supercritical CO2 leakage and diffusion similarity model experimental system according to claim 4 is characterized in that: The heating system includes a heating blanket and a heating tape; The two heating blankets are respectively arranged at the two ends of the storage tank, and the heating belt is arranged on the outer periphery of the third pipeline. The heating blanket and the heating belt are respectively used to heat the CO2 in the storage tank or in the third pipeline.

6. The dense phase supercritical CO2 leakage and diffusion similarity model experimental system according to claim 1 is characterized in that: The leakage system comprises a flange, a fourth pipeline and a leakage nozzle; One end of the fourth pipeline is used to connect with the third pipeline of the reaction system; The other end of the fourth pipeline is connected to the leakage nozzle; The fourth pipeline is divided into multiple sections, and the multiple sections of the fourth pipeline are connected by flanges; The fourth pipeline is provided with a fifth ball valve.

7. The dense phase supercritical CO2 leakage and diffusion similarity model experimental system according to claim 6 is characterized in that: The data acquisition system includes a data recorder, a concentration sensor and a temperature sensor; The concentration sensor is used to detect the concentration of CO2 sprayed from the leakage nozzle; The temperature sensor is used to detect the temperature of CO2 sprayed from the leaking nozzle; The data recorder is used to record the concentration and temperature of CO2 ejected from the leaking nozzle.

8. An experimental method based on the dense phase supercritical CO2 leakage and diffusion similarity model experimental system according to any one of claims 1 to 7, characterized in that: The steps include: Scale down the set offshore platform; Based on the scaled-down processing of the assumed offshore platform, the key parameters in the experiment are determined; Based on the key parameters in the experiment, a dense phase supercritical CO2 leakage and diffusion experiment was carried out according to the experimental system.

9. The experimental method according to claim 8, characterized in that: The scaling down of the offshore platform specifically includes the following steps: Assume the actual length of the offshore platform deck is L, the width is D, the height is H, and the inner diameter of the leaking pipe is E; Based on the processing cost, site size and experimental operation, the geometric model of the offshore platform is converted into a 1:n 2 To scale, Where: subscripts δ1 and δ2 represent the geometric dimensions of the model and prototype respectively; is the similarity ratio; The length l, width d, height h of the offshore platform model in the experiment, and the inner diameter e of the pipeline are calculated according to the similarity ratio.

10. The experimental method according to claim 8, characterized in that: The specific steps to determine the key parameters in the experiment are: Assuming the instantaneous leakage mass flow rate of CO2 at a certain point in the pipeline is Q, under the influence of the ambient wind speed v, the change of the CO2 volume fraction C at the distance s from the leakage port after time t is: Where: x, y, z are dimensional indices; Based on similarity theory, the dimensional analysis of formula (2) can be transformed into: Where: π1 is a dimensionless quantity; L is the length dimension, T is the time dimension; M is the mass dimension; According to the principle of dimensional homogeneity, we can get from formula (3): Solving the system of equations, we get x=0, y=1, z=-1; Therefore, formula (3) can be written as: Since the geometric ratio is 1:n 2 , the time scale t1:t2 is 1:

1. According to the relationship of formula (5), the geometric scale and the time scale, the ratio of the experimental wind speed v1 to the actual wind speed v2 is calculated to be 1:n 2 The ratio of the experimental leakage aperture e to the actual leakage aperture E is 1:n 2 , the ratio of the experimental leakage pressure to the actual leakage pressure is the square root of the geometric scale, that is, 1:n.

11. The experimental method according to claim 8, characterized in that: The dense phase supercritical CO2 leakage and diffusion experiment carried out according to the experimental system specifically includes the following steps: (1) Connect the experimental equipment according to the experimental system diagram; (2) Place a CO2 concentration sensor at the target location to measure the CO2 concentration and connect it to the data acquisition system; (3) Open the liquid outlet valve, the second ball valve, the third ball valve and the fifth ball valve of the liquid CO2 Dewar flask, purge the pipeline and check for leaks; (4) Liquid CO2 filling, including: a) Close the liquid outlet valve, the first ball valve 1 and the fourth ball valve, and open the second ball valve, the third ball valve and the fifth ball valve; b) Open the liquid outlet valve and set the cooling time for the liquid CO2 pump; c) After the pump has been cooled, turn on the motor of the liquid CO2 pump, close the fifth ball valve, start the liquid CO2 pump and adjust the speed of the pump to inject the liquid CO2 into the storage tank. When the pressure gauge of the storage tank is greater than 4MPa, close the liquid CO2 pump, the second ball valve and the liquid outlet valve in sequence; d) Open the first ball valve to exhaust the CO2 in the pump and the CO2 in the first tube 1; (5) Supercritical CO2 preparation, specifically including: a) After the filling is completed, the temperature in the tank is lower than the set value, and the heating blanket and heating belt are turned on to heat the reaction system; b) monitoring the pressure in the reaction system during the heating process, and when the pressure exceeds the set value, opening the fourth ball valve to release the pressure, and when the pressure drops to the set value, closing the fourth ball valve; c) When the pressure in the reaction system exceeds the set value and the temperature exceeds the set value, the supercritical CO2 preparation is completed; (6) Install the corresponding leakage nozzle according to the selected leakage diameter and leakage direction, and connect the leakage system to the tube reaction system using the flange; (7) Supercritical CO2 leakage experiment, including: a) Arrange a camera to record the supercritical CO2 leakage process; b) Open the fifth ball valve and start the supercritical CO2 leakage experiment. When the leakage time is reached, close the fifth ball valve and record the concentration and temperature data; c) After completing a set of experiments, the pressure and temperature of the reaction system will drop. Continue heating until the pressure reaches the requirements of the next set of experiments and repeat (7).

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