Supercritical phase carbon dioxide and associated gas mixing experimental device and experimental method

Abstract

The invention discloses a supercritical phase carbon dioxide and associated gas mixing experimental device and experimental method. The supercritical phase carbon dioxide and associated gas mixing experimental device comprises a CO2 preparation and phase state control system, a CO2 and associated gas injection system, a flow pattern control system, a CO2 and associated gas sufficient mixing system and a monitoring and control system. According to the invention, the mixing process of supercritical phase carbon dioxide and associated gas can be accurately controlled, the real flow condition of fluid in the pipeline under different mixing angles, different flows and different flow patterns can be simulated, and the phase state layering, interface fluctuation and mixing diffusion process of supercritical phase carbon dioxide and associated gas in the pipeline can be accurately observed and recorded; data can be automatically collected through a computer system, a parameter change curve can be generated, and an operator can control starting, stopping and power of all devices through a computer; the device has the advantages of being visual in experimental result, good in safety performance, convenient to operate and the like, and has important significance on revealing a supercritical phase carbon dioxide and associated gas mixing mechanism and formulating an associated gas separation and recovery scheme.

Description

Technical Field

[0001] The present invention relates to the technical field of mixed treatment of CO 2 and associated oilfield gas, and specifically to an experimental device and method for mixing supercritical-phase carbon dioxide and associated gas. Background Technique

[0002] Under the background of "dual carbon", as a key link in CCUS (carbon dioxide capture, utilization and storage), CO2 flooding technology has become an important means to improve oilfield recovery rate and achieve carbon sequestration. CO2 flooding injects high-pressure CO2 into oil wells, reduces the viscosity of crude oil, increases the volume of crude oil, and drives out the oil in the rock pores by virtue of the strong penetration ability of CO2. Supercritical-phase CO2 can also be used as an extractant to further improve the recovery rate. With the development of oilfields, a large amount of associated oilfield gas is generated, and the potential for treatment, recovery and utilization of associated gas is huge. However, the CO2 content in the associated gas produced in the middle and late stages of CO2 flooding can reach more than 40%. Especially under high temperature and high pressure conditions, the mixing uniformity of supercritical-phase CO2 and associated gas directly affects the subsequent separation efficiency. Uneven mixing is likely to cause phase instability, local condensation and equipment corrosion, resulting in increased separation energy consumption and process complexity.

[0003] The separation difficulty of carbon dioxide in different states after mixing with associated gas varies greatly. Gas-phase, liquid-phase and dense-phase carbon dioxide are relatively easy to separate from associated gas by simple methods such as pressure reduction. However, the density of supercritical-phase carbon dioxide is close to that of the liquid phase and the viscosity is close to that of the gas phase. The system is complex after mixing with associated gas, and traditional separation technologies such as gravity sedimentation fail.

[0004] To facilitate the development of carbon dioxide and associated gas separation technology, improve the CO2 capture efficiency and the utilization rate of associated gas, it is urgent to design an experimental device and method for mixing supercritical-phase CO 2 and associated gas, conduct research on the mixing mechanism of supercritical-phase carbon dioxide and associated gas, analyze the diffusion and mixing effects of supercritical-phase carbon dioxide and associated gas under different working conditions, and provide a basis for the design and installation location of the separation device. Summary of the Invention

[0005] In order to accurately explore the mixing mechanism of supercritical-phase carbon dioxide and associated gas, the present invention provides an experimental device and method for mixing supercritical-phase carbon dioxide and associated gas. This experimental device can accurately control the temperature, pressure and phase state of carbon dioxide and associated gas under set working conditions, precisely control the mixing angle of carbon dioxide and associated gas, and achieve flow pattern control and dynamic visualization of the flow process, and observe the fluid phase state and mixing state in the pipeline in real time.

[0006] To achieve the above purpose, the present invention adopts the following technical solution: an experimental device for mixing supercritical-phase carbon dioxide and associated gas, which device includes CO 2Preparation and phase state control system, CO 2 With associated gas injection system, flow pattern control system, CO 2 Fully mixed system with associated gas and monitoring and control system.

[0007] The CO 2 The preparation and phase state control system includes a liquid-phase CO 2 bottle (1), first electric contact pressure gauge (2), first needle valve (3), first booster pump (4), second electric contact pressure gauge (5), second needle valve (6), CO 2 inlet pipeline (41), CO 2 reaction kettle (7), first electric heating device (49), first thermocouple (47), first pressure sensor (48), first discharge pipe (45), first quick-opening valve (8) and first scale regulating valve (9), the CO 2 The first electric contact pressure gauge (2), the first needle valve (3), the first booster pump (4), the second electric contact pressure gauge (5) and the second needle valve (6) are provided on the CO 2 inlet pipeline (41), the intake direction of the first needle valve (3) is communicated with the liquid-phase CO 2 bottle (1), the first discharge pipe (45) is inserted into the surface of the CO 2 reaction kettle (7), the first quick-opening valve (8) and the first scale regulating valve (9) are sequentially connected in the normal direction of the reaction kettle (7) from the insertion point to the CO 2 The reaction kettle (7) is internally provided with the first electric heating device (49), the first thermocouple (47) and the first pressure sensor (48).

[0008] The CO 2The associated gas injection system includes a natural gas cylinder (10), a third electric contact pressure gauge (11), a third needle valve (12), a second booster pump (13), a fourth electric contact pressure gauge (14), a fourth needle valve (15), a natural gas inlet pipeline (42), a natural gas reactor (16), a second electric heating device (52), a second thermocouple (50), a second pressure sensor (51), a second discharge pipe (46), a second quick-opening valve (17), a second scale regulating valve (18), a fifth needle valve (19), a sixth needle valve (20), a first flow controller (21), a second flow controller (22), and a first replaceable pipe section (23). The third electric contact pressure gauge (11), the third needle valve (12), the second booster pump (13), the fourth electric contact pressure gauge (14), and the fourth needle valve (15) are provided on the natural gas inlet pipeline (42). The inlet direction of the third needle valve (12) is connected to the natural gas cylinder (10). The second discharge pipe (46) is inserted into the surface of the natural gas reactor (16), and the second quick-opening valve (17) and the second scale regulating valve (18) are sequentially connected in the normal direction of the natural gas reactor (16) from the insertion point. The second electric heating device (52), the second thermocouple (50), and the second pressure sensor (51) are arranged inside the natural gas reactor (16). The first replaceable pipe section (23) is respectively connected to the CO 2 reactor (7) and the natural gas reactor (16). The sixth needle valve (20) and the first flow controller (21) are provided on the side where the first replaceable pipe section (23) is connected to the CO 2 reactor (7). The fifth needle valve (19) and the second flow controller (22) are provided on the side where the first replaceable pipe section (23) is connected to the natural gas reactor (16).

[0009] The flow pattern control system includes a second replaceable pipe section (25), a seventh needle valve (24), and an eighth needle valve (26). The first replaceable pipe section (23) is connected to the second replaceable pipe section (25). The seventh needle valve (24) and the eighth needle valve (26) are provided on both sides of the second replaceable pipe section (25).

[0010] The CO 2The system for fully mixing with associated gas includes a ninth needle valve (34), a tenth needle valve (36), a circulation pump (37), an eleventh needle valve (38), a fully developed pipeline (43) and a circulation pipeline (44). The second replaceable pipe section (25) is communicated with the fully developed pipeline (43), the fully developed pipeline (43) is communicated with the circulation pipeline (44), and the ninth needle valve (34), the tenth needle valve (36), the circulation pump (37) and the eleventh needle valve (38) are arranged on the circulation pipeline (44).

[0011] The monitoring and control system includes a first methane sensor (27), a second methane sensor (28), a third methane sensor (29), a fourth methane sensor (30), a fifth methane sensor (31), an upper sampling port (32), a lower sampling port (33), an anti-high-pressure visual window (35), a high-definition camera (39) and a computer (40). The first methane sensor (27), the second methane sensor (28), the third methane sensor (29), the fourth methane sensor (30) and the fifth methane sensor (31) are arranged on the fully developed pipeline (43) and the circulation pipeline (44). The anti-high-pressure visual window (35) is installed between the fourth methane sensor (30) and the fifth methane sensor (31). The upper sampling port (32) and the lower sampling port (33) are arranged on one side of the fourth methane sensor (30) of the anti-high-pressure visual window (35). The high-definition camera (39) is arranged outside the anti-high-pressure visual window (35). The computer (40) is connected with the first booster pump (4), the second booster pump (13), the first electric heating device (49), the second electric heating device (52), the first thermocouple (47), the second thermocouple (50), the first pressure sensor (48), the second pressure sensor (51), the first flow controller (21), the second flow controller (22), the first methane sensor (27), the second methane sensor (28), the third methane sensor (29), the fourth methane sensor (30), the fifth methane sensor (31) and the circulation pump (37) through data lines.

[0012] The present invention adopts the above technical solutions and can achieve the following beneficial effects:

[0013] 1. The present invention can accurately control the mixing process of supercritical carbon dioxide and associated gas, simulate the real flow conditions of the fluid in the pipeline at different mixing angles, different flow rates and different flow patterns (stratified flow / turbulent flow), and can accurately observe and record the phase stratification, interface fluctuation and mixing diffusion process of supercritical carbon dioxide and associated gas in the pipeline.

[0014] 2. It can automatically collect data through a computer system and generate a parameter change curve, and the operator can control the start-stop and power of each device through the computer.

[0015] 3. It has the advantages of intuitive experimental results, good safety performance, and convenient operation, and is of great significance for revealing the mixing mechanism of supercritical-phase carbon dioxide and associated gas and formulating a separation and recovery plan for associated gas. Description of the Drawings

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0017] Figure 1 It is a process diagram of the supercritical-phase carbon dioxide and associated gas mixing experimental device of the present invention.

[0018] Figure 2 It is a carbon dioxide phase diagram.

[0019] Figure 3 It is a schematic diagram of the first replaceable pipeline structure of the present invention.

[0020] Figure 4 It is a diagram of the second replaceable pipeline device of the present invention.

[0021] In the figure: 1 liquid-phase CO 2 bottle, 2, second electric contact pressure gauge, 3, first needle valve, 4, first booster pump, 5, second electric contact pressure gauge, 6, second needle valve, 7, CO 2 reaction kettle, 8, first quick-opening valve, 9, first scale regulating valve, 10, natural gas bottle, 11, third electric contact pressure gauge, 12, third needle valve, 13, second booster pump, 14, fourth electric contact pressure gauge, 15, fourth needle valve, 16, natural gas reaction kettle, 17, second quick-opening valve, 18, second scale regulating valve, 19, fifth needle valve, 20, sixth needle valve, 21, first flow controller, 22, second flow controller, 23, first replaceable pipe section, 24, seventh needle valve, 25, second replaceable pipe section, 26, eighth needle valve, 27, first methane sensor, 28, second methane sensor, 29, third methane sensor, 30, fourth methane sensor, 31, fifth methane sensor, 32, upper sampling port, 33, lower sampling port, 34, ninth needle valve, 35, high-pressure resistant viewing window, 36, tenth needle valve, 37, circulation pump, 38, eleventh needle valve, 39, high-definition camera, 40, computer, 41, CO 2Intake pipeline, 42. Natural gas intake pipeline, 43. Fully developed pipeline, 44. Circulation pipeline, 45. First drain pipe, 46. Second drain pipe, 47. First thermocouple, 48. First pressure sensor, 49. First electric heating device, 50. Second thermocouple, 51. Second pressure sensor, 52. Second electric heating device. Detailed implementation manners

[0022] To enable those skilled in the art to better understand the solutions of this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only a part rather than all of the embodiments of this application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application without creative efforts shall fall within the scope of protection of this application.

[0023] Taking the mixed transportation of supercritical carbon dioxide and associated gas as an experimental example below, supercritical phase CO 2 The temperature is 40 °C and the pressure is 10 MPa. The test pipeline is 40-meter-long 316L stainless steel, with a pipeline diameter of DN32 and a wall thickness of 2 mm.

[0024] As Figure 1 shown, a supercritical phase carbon dioxide and associated gas mixing experimental device, which includes a CO 2 preparation and phase control system, a CO 2 and associated gas injection system, a flow pattern control system, a CO 2 and associated gas full mixing system, and a monitoring and control system.

[0025] CO 2 The preparation and phase control system includes a liquid-phase CO 2 bottle 1, a first electric contact pressure gauge 2, a first needle valve 3, a first booster pump 4, a second electric contact pressure gauge 5, a second needle valve 6, a CO 2 intake pipeline 41, a CO 2 reaction kettle 7, a first drain pipe 45, a first quick-opening valve 8, and a first scale regulating valve 9. A first electric contact pressure gauge 2, a first needle valve 3, a first booster pump 4, a second electric contact pressure gauge 5, and a second needle valve 6 are provided on the CO 2 intake pipeline 41. The intake direction of the first needle valve 3 is connected to the liquid-phase CO 2 bottle 1. The first drain pipe 45 is inserted into the surface of the CO 2 reaction kettle 7. A first quick-opening valve 8 and a first scale regulating valve 9 are sequentially connected in the normal direction of the CO 2 reaction kettle 7 from the insertion point. The CO 2 reaction kettle 7 is internally provided with a first electric heating device 49, a first thermocouple 47, and a first pressure sensor 48.

[0026] CO 2 The associated gas injection system includes a natural gas cylinder 10, a third electric contact pressure gauge 11, a third needle valve 12, a second booster pump 13, a fourth electric contact pressure gauge 14, a fourth needle valve 15, a natural gas inlet pipeline 42, a natural gas reactor 16, a second drain pipe 46, a second quick-opening valve 17, a second scale regulating valve 18, a fifth needle valve 19, a sixth needle valve 20, a first flow controller 21, a second flow controller 22 and a first replaceable pipe section 23. The third electric contact pressure gauge 11, the third needle valve 12, the second booster pump 13, the fourth electric contact pressure gauge 14 and the fourth needle valve 15 are provided on the natural gas inlet pipeline 42. The inlet direction of the third needle valve 12 is connected to the natural gas cylinder 10. The second drain pipe 46 is inserted into the surface of the natural gas reactor 16, and the second quick-opening valve 17 and the second scale regulating valve 18 are sequentially connected in the normal direction of the natural gas reactor 16 from the insertion point. The natural gas reactor 16 is internally provided with a second electric heating device 52, a second thermocouple 50 and a second pressure sensor 51. The first replaceable pipe section 23 is respectively connected to the CO 2 reactor 7 and the natural gas reactor 16. The side of the first replaceable pipe section 23 connected to the CO 2 reactor 7 is provided with a sixth needle valve 20 and a first flow controller 21. The side of the first replaceable pipe section 23 connected to the natural gas reactor 16 is provided with a fifth needle valve 19 and a second flow controller 22.

[0027] The flow pattern control system includes a second replaceable pipe section 25, a seventh needle valve 24 and an eighth needle valve 26. The first replaceable pipe section 23 is connected to the second replaceable pipe section 25. The seventh needle valve 24 and the eighth needle valve 26 are provided on both sides of the second replaceable pipe section 25.

[0028] CO 2 The associated gas and CO full mixing system includes a ninth needle valve 34, a tenth needle valve 36, a circulation pump 37, an eleventh needle valve 38, a fully developed pipeline 43 and a circulation pipeline 44. The second replaceable pipe section 25 is connected to the fully developed pipeline 43. The fully developed pipeline 43 is connected to the circulation pipeline 44. The ninth needle valve 34, the tenth needle valve 36, the circulation pump 37 and the eleventh needle valve 38 are provided on the circulation pipeline 44.

[0029] The monitoring and control system includes a first methane sensor 27, a second methane sensor 28, a third methane sensor 29, a fourth methane sensor 30, a fifth methane sensor 31, an upper sampling port 32, a lower sampling port 33, an anti-high-pressure visible window 35, a high-definition camera 39, and a computer 40. The first methane sensor 27, the second methane sensor 28, the third methane sensor 29, the fourth methane sensor 30, and the fifth methane sensor 31 are provided on the fully developed pipeline 43 and the circulation pipeline 44. An anti-high-pressure visible window 35 is installed between the fourth methane sensor 30 and the fifth methane sensor 31. The anti-high-pressure visible window 35 is provided with an upper sampling port 32 and a lower sampling port 33 on one side of the fourth methane sensor 30. A high-definition camera 39 is provided outside the anti-high-pressure visible window 35 to record in real time the fluid flow state and the CO 2 image of the mixing and stratification situation of the natural gas mixture. The computer 40 is connected to the first booster pump 4, the second booster pump 13, the first electric heating device 49, the second electric heating device 52, the first thermocouple 47, the second thermocouple 50, the first pressure sensor 48, the second pressure sensor 51, the first flow control instrument 21, the second flow control instrument 22, the first methane sensor 27, the second methane sensor 28, the third methane sensor 29, the fourth methane sensor 30, the fifth methane sensor 31, and the circulation pump 37 through data lines, and can collect the data of each instrument in real time, form corresponding parameter change curves, and control the start-stop and power of each device.

[0030] In this embodiment, by liquefying the liquid-phase CO 2 in the liquid-phase CO 2 bottle 1 by the booster pump 4 and pumping it into the CO 2 reactor 7, the conversion of liquid-phase CO 2 to dense-phase CO 2 can be completed; by heating the dense-phase CO 2 in the reactor 7 by the electric heating device 49, the conversion of dense-phase CO 2 to supercritical-phase CO 2 can be completed. 2

[0031] In this embodiment, the quick-opening valve is an internal-thread ball valve, and the scale regulating valve is a high-precision scale regulating valve. By opening the quick-opening valves 8 and 17, the rapid discharge of the CO 2 reactor 7 and the natural gas reactor 16 can be realized; by accurately controlling the discharge aperture through the scale regulating valves 9 and 18, the discharge and pressure reduction under different apertures can be realized.

[0032] ​In this embodiment, through the high-pressure resistant visual window 35, the stratification of supercritical carbon dioxide and associated gas under various flow patterns and different mixing angles can be observed, and through the high-definition camera 39, the flow state and mixing condition of the fluid in the pipe during the dynamic mixing process of supercritical carbon dioxide and associated gas can be recorded in real time.

[0033] In this embodiment, an upper sampling port 32 and a lower sampling port 33 are respectively arranged on the circulation pipeline 44, so as to sample the mixed medium after mixing and conduct physical property tests, and the density, molecular weight, etc. of the mixed medium at different positions can be tested.

[0034] In this embodiment, the pressure of the liquid-phase CO 2 bottle 1 can be observed through the first electric contact pressure gauge 2, and by rotating the pressure setting pointer of the second electric contact pressure gauge 5, the upper and lower limits of the pressure in the connecting pipeline can be set to prevent the pressure from exceeding the preset range, so as to ensure the safe and stable operation of the system.

[0035] In this embodiment, the first needle valve 3, the second needle valve 6, the third needle valve 12, the fourth needle valve 15, the fifth needle valve 19, the sixth needle valve 20, the seventh needle valve 24, the eighth needle valve 26, the ninth needle valve 34, the tenth needle valve 36 and the eleventh needle valve 38 are all needle valves to accurately control the flow rate of the fluid and provide better sealing performance.

[0036] In this embodiment, the computer 40 is connected to the booster pump, the electric heating device, the thermocouple and the pressure sensor through data lines, and can collect the data of each instrument in real time, form the corresponding parameter change curve, and control the start-stop and power of each device.

[0037] The present invention can accurately measure and observe the dynamic mixing of supercritical carbon dioxide and associated gas under different flow patterns and different mixing angles under set working conditions, and specifically includes the following steps:

[0038] Step S1: Open the first needle valve 3, the second needle valve 6, the third needle valve 12 and the fourth needle valve 15, and all other valves in the system are in the closed state; the liquid-phase CO 2 in the bottle 1 of liquid-phase CO 2 is pumped into the CO 2 reactor 7 through the first booster pump 4, and combined with Figure 2 , the liquid-phase CO 2 is pressurized to the critical pressure of 7.38 MPa to complete the conversion of liquid-phase CO 2 to dense-phase CO 2 ; the dense-phase CO 2 in the CO 2 reactor 7 is heated through the electric heating device, and combined with Figure 2 , the temperature is raised to the critical temperature of 31.1 °C to complete the dense-phase CO 2to supercritical phase CO 2 conversion. The natural gas in the natural gas cylinder 10 is pumped into the natural gas reactor 16 by the second booster pump 13.

[0039] Step S2: Open the fifth needle valve 19, the sixth needle valve 20, the seventh needle valve 24, the eighth needle valve 26, the ninth needle valve 34, the tenth needle valve 36 and the circulation pump 37. Set the frequency of the circulation pump 37 to 30 Hz through the computer 40, and control the flow rates of the supercritical phase CO 2 and natural gas entering the fully developed pipe 43 and the circulation pipe 44 respectively through the first flow controller 21 and the second flow controller 22.

[0040] It should be noted that the circulation pump 37 adopts a high-pressure resistant magnetic drive pump, with a rotational speed of 2900 r / min and a flow rate of 3 m 3 / h. Set the frequency of the circulation pump 37 through the computer 40 to control the rotational speed of the circulation pump 37, thereby controlling the flow velocity of the mixture in the pipeline.

[0041] Step S3: Turn on the high-definition camera 39. After the supercritical phase CO 2 and natural gas mixture in the fully developed pipe 43 and the circulation pipe 44 flow stably, record the flow and stratification of the mixture through the high-pressure resistant viewing window 35.

[0042] Step S4: Detect the methane concentration at different positions in the pipeline through the first methane sensor 27, the second methane sensor 28, the third methane sensor 29, the fourth methane sensor 30 and the fifth methane sensor 31.

[0043] Step S5: Adjust the first flow controller 21 and the second flow controller 22 through the computer 40, and observe the mixing and stratification of the supercritical phase CO 2 and natural gas and the methane concentration distribution under different flow rates.

[0044] Step S6: Take samples of the mixture through the upper sampling port 32 and the lower sampling port 33, and test the physical properties such as the medium density, compression factor, uniformity, viscosity, etc. to explore the variation law of the physical properties of the blending medium.

[0045] Step S7: Replace each replaceable pipe section structure as shown in Figure 3 through the first replaceable pipe section 23, restart the device, and observe the mixing and stratification of the supercritical phase CO 2 and natural gas and the methane concentration distribution under different mixing angles.

[0046] Step S8: Replace different flow pattern controllers as shown in Figure 4 through the second replaceable pipe section 25, restart the device, and observe the supercritical phase CO 2and natural gas mixing stratification and methane concentration distribution.

[0047] Step S9: Perform sensitivity analysis on factors affecting the mixing effect of supercritical / dense phase carbon dioxide and natural gas (including pressure, temperature, flow rate ratio, mixing angle and flow pattern control device structure, etc.) by controlling variable method. Under the condition of keeping other parameters constant, change single variables one by one, and record the mixture density, compression factor, methane concentration distribution and mixed stratification at each test point. Based on the collected data, statistical analysis is performed by computer to draw trend curves of mixing effect with changes in key variables, so as to identify the variables that most significantly affect mixing uniformity, and provide data support for subsequent equipment optimization design and operation parameter selection.

[0048] Beneficial effects of the present invention: The present invention uses a CO2 reactor, a booster pump, an electric heating device, a circulating pump and multiple sets of needle valves to accurately adjust the temperature, pressure and flow rate of liquid phase CO2 and natural gas to achieve phase conversion of liquid phase CO2 to dense phase CO2 and supercritical phase CO2, and accurately control the temperature, pressure and flow rate during the natural gas injection process, thereby ensuring the stability and controllability of the experimental working conditions. The computer is connected with the thermocouple, pressure sensor, methane sensor, mass flow meter, circulating pump, booster pump and electric heating device by data line, which can realize the computer to start and stop the circulating pump, booster pump, and electric heating device and adjust the power, and collect experimental data in real time and generate temperature, pressure, flow and methane concentration change curves, which provides highly automated data recording and analysis functions for the experimental process, greatly facilitating the operation of researchers. By adopting a replaceable flow type control device and a pipe section design with replaceable mixing angles, it is possible to realize experimental research on the mixing process of supercritical phase CO2 and associated gas with different mixing angles and different flow types, further improving the flexibility and applicability of the experiment. With the high-definition camera and the high-pressure resistant visual window, the flow state and stratification of the mixed medium under different flow patterns and different mixing angles can be observed in real time. In addition, by arranging multiple groups of methane sensors, real-time detection of changes in methane concentration of the mixed medium at different pipe sections can be achieved. In general, the present invention can conduct blending experiments of supercritical phase CO2 and associated gas under different temperatures, pressures, flow rate ratios, mixing angles and flow patterns under high temperature and high pressure conditions. It has the advantages of short experimental cycle and high test accuracy, and has strong safety and controllability. It can provide scientific experimental data and theoretical support for the design of separation devices in natural gas gathering and transportation, CCUS (carbon capture, utilization and storage) and associated gas recovery.

[0049] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A supercritical phase carbon dioxide and associated gas mixing experimental device, characterized in that: It includes CO2 preparation and phase control system, CO2 and associated gas injection system, flow control system, CO2 and associated gas full mixing system and monitoring and control system, among which: The CO2 preparation and phase control system comprises a liquid CO2 bottle (1), a first electric contact pressure gauge (2), a first needle valve (3), a first booster pump (4), a second electric contact pressure gauge (5), a second needle valve (6), a CO2 intake pipeline (41), a CO2 reactor (7), a first electric heating device (49), a first thermocouple (47), a first pressure sensor (48), a first discharge pipe (45), a first quick-opening valve (8) and a first scale regulating valve (9). The CO2 intake pipeline (41) is provided with the first electric contact pressure gauge (2), the first needle valve (3), a first booster pump (4), a second electric contact pressure gauge (5), a second needle valve (6), a CO2 intake pipeline (41), a CO2 reactor (7), a first electric heating device (49), a first thermocouple (47), a first pressure sensor (48), a first discharge pipe (45), a first quick-opening valve (8) and a first scale regulating valve (9). valve (3), the first booster pump (4), the second electric contact pressure gauge (5) and the second needle valve (6), the first needle valve (3) is connected to the liquid CO2 bottle (1) in the air inlet direction, the first discharge pipe (45) is inserted into the surface of the CO2 reactor (7), and is connected to the first quick-opening valve (8) and the first scale regulating valve (9) in sequence from the insertion point to the normal direction of the CO2 reactor (7), and the CO2 reactor (7) is built-in with the first electric heating device (49), the first thermocouple (47) and the first pressure sensor (48); The CO2 and associated gas injection system comprises a natural gas cylinder (10), a third electric contact pressure gauge (11), a third needle valve (12), a second booster pump (13), a fourth electric contact pressure gauge (14), a fourth needle valve (15), a natural gas intake pipeline (42), a natural gas reactor (16), a second electric heating device (52), a second heating couple (50), a second pressure sensor (51), a second discharge pipe (46), a second quick-opening valve (17), a second scale regulating valve (18), a fifth needle valve (19), a sixth needle valve (20), a first flow controller (21), a second flow controller (22) and a first replaceable pipe section (23). The natural gas intake pipeline (42) is provided with the third electric contact pressure gauge (11), the third needle valve (12), the second booster pump (13), the fourth electric contact pressure gauge (14) and the fourth needle valve (15). The third needle valve (12) the gas inlet direction is connected to the natural gas cylinder (10); the second discharge pipe (46) is inserted into the surface of the natural gas reactor (16); the second quick-opening valve (17) and the second scale regulating valve (18) are connected in sequence from the insertion point to the normal direction of the natural gas reactor (16); the natural gas reactor (16) is equipped with the second electric heating device (52), the second thermocouple (50) and the second pressure sensor (51); the first replaceable pipe section (23) is respectively connected to the CO2 reactor (7) and the natural gas reactor (16); the sixth needle valve (20) and the first flow controller (21) are provided on the side of the first replaceable pipe section (23) connected to the CO2 reactor (7); the fifth needle valve (19) and the second flow controller (22) are provided on the side of the first replaceable pipe section (23) connected to the natural gas reactor (16); The flow pattern control system comprises a second replaceable pipe section (25), a seventh needle valve (24) and an eighth needle valve (26); the first replaceable pipe section (23) is connected to the second replaceable pipe section (25); the seventh needle valve (24) and the eighth needle valve (26) are provided on both sides of the second replaceable pipe section (25); The CO2 and associated gas fully mixing system comprises a ninth needle valve (34), a tenth needle valve (36), a circulation pump (37), an eleventh needle valve (38), a fully developed pipeline (43) and a circulation pipeline (44); the second replaceable pipe section (25) is connected to the fully developed pipeline (43); the fully developed pipeline (43) is connected to the circulation pipeline (44); the ninth needle valve (34), the tenth needle valve (36), the circulation pump (37) and the eleventh needle valve (38) are provided on the circulation pipeline (44); The monitoring and control system comprises a first methane sensor (27), a second methane sensor (28), a third methane sensor (29), a fourth methane sensor (30), a fifth methane sensor (31), an upper sampling port (32), a lower sampling port (33), a high-pressure resistant visual window (35), a high-definition camera (39) and a computer (40); the first methane sensor (27), the second methane sensor (28), the third methane sensor (29), the fourth methane sensor (30) and the fifth methane sensor (31) are provided on the fully developed pipeline (43) and the circulating pipeline (44); the high-pressure resistant visual window (35) is installed between the fourth methane sensor (30) and the fifth methane sensor (31); the high-pressure resistant visual window (35) is located on the fourth methane sensor (3 0) is provided with the upper sampling port (32) and the lower sampling port (33) on one side, the high-definition camera (39) is provided outside the high-pressure resistant visual window (35), and the computer (40) is connected to the first booster pump (4), the second booster pump (13), the first electric heating device (49), the second electric heating device (52), the first thermocouple (47), the second thermocouple (50), the first pressure sensor (48), the second pressure sensor (51), the first flow controller (21), the second flow controller (22), the first methane sensor (27), the second methane sensor (28), the third methane sensor (29), the fourth methane sensor (30), the fifth methane sensor (31) and the circulation pump (37) through a data line.

2. The experimental method of the supercritical phase carbon dioxide and associated gas mixing experimental device according to claim 1, characterized in that: The following steps are involved: Step S1: Open the first needle valve 3, the second needle valve 6, the third needle valve 12 and the fourth needle valve 15, and all other valves in the system are in a closed state; the liquid CO2 in the liquid CO2 bottle 1 is pumped into the CO2 reactor 7 through the first booster pump 4, and in conjunction with Figure 2, the liquid CO2 is pressurized to a critical pressure of 7.38 MPa to complete the conversion of the liquid CO2 to dense CO2; the dense CO2 in the CO2 reactor 7 is heated by an electric heating device, and in conjunction with Figure 2, the temperature is raised to a critical temperature of 31.1°C to complete the conversion of the dense CO2 to the supercritical CO2, and the natural gas in the natural gas bottle 10 is pumped into the natural gas reactor 16 through the second booster pump 13; Step S2: Open the fifth needle valve 19, the sixth needle valve 20, the seventh needle valve 24, the eighth needle valve 26, the ninth needle valve 34, the tenth needle valve 36 and the circulation pump 37, set the frequency of the circulation pump 37 to 30 Hz through the computer 40, and control the flow rates of the supercritical phase CO2 and natural gas entering the fully developed pipeline 43 and the circulation pipeline 44 respectively through the first flow controller 21 and the second flow controller 22; It should be noted that the circulation pump 37 adopts a high-pressure magnetic drive pump with a rotation speed of 2900r / min and a flow rate of 3m 3 / h, the frequency of the circulation pump 37 is set by the computer 40, and the speed of the circulation pump 37 is controlled, thereby controlling the flow rate of the mixture in the pipeline; Step S3: Turn on the high-definition camera 39, and after the supercritical phase CO2 and natural gas mixture in the pipeline 43 and the circulation pipeline 44 flows stably, record the mixture flow and stratification through the high-pressure resistant visual window 35; Step S4: detecting methane concentrations at different positions of the pipeline by means of the first methane sensor 27, the second methane sensor 28, the third methane sensor 29, the fourth methane sensor 30 and the fifth methane sensor 31; Step S5: adjusting the first flow controller 21 and the second flow controller 22 by the computer 40 to observe the mixed stratification of supercritical phase CO2 and natural gas and the distribution of methane concentration at different flow rates; Step S6: sampling the mixture through the upper sampling port 32 and the lower sampling port 33, testing the physical properties such as medium density, compression factor, uniformity, viscosity, etc., to explore the change law of the physical properties of the mixed medium; Step S7: replacing the replacement pipe segment structures shown in FIG. 3 through the first replaceable pipe segment 23, restarting the device, and observing the mixed stratification of supercritical phase CO2 and natural gas and the methane concentration distribution at different mixing angles; Step S8: Replace the different flow pattern controllers shown in FIG. 4 through the second replaceable pipe section 25, restart the device, and observe the mixed stratification of supercritical phase CO2 and natural gas and the distribution of methane concentration under different flow patterns (stratified flow / turbulent flow); Step S9: Perform sensitivity analysis on factors affecting the mixing effect of supercritical / dense phase carbon dioxide and natural gas (including pressure, temperature, flow rate ratio, mixing angle and flow pattern control device structure, etc.) by controlling variable method. While keeping other parameters constant, change single variables one by one, record the mixture density, compression factor, methane concentration distribution and mixing stratification at each test point, and based on the collected data, perform statistical analysis by computer to draw trend curves of mixing effect with changes in key variables, so as to identify the variables that most significantly affect mixing uniformity, and provide data support for subsequent equipment optimization design and operation parameter selection.

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