Carbon dioxide-rich phase electrochemical corrosion in-situ test system and method

Abstract

The invention discloses a carbon dioxide-rich phase electrochemical corrosion in-situ test system and method. The system comprises a carbon dioxide pressurizing device, a reaction kettle, a heating device, a first test piece and an electrochemical analyzer, the carbon dioxide pressurizing device is used for preparing pressurized carbon dioxide and injecting the pressurized carbon dioxide into the reaction kettle; the reaction kettle is used for providing and maintaining a stable set temperature and pressure environment in the kettle; the heating device comprises a temperature control system and a heating jacket, the heating jacket covers the reaction kettle, and the reaction kettle is heated under the control of the temperature control system; and the two first test pieces form double electrodes which are electrically connected with an electrochemical tester through wires. The double electrodes are composed of two first test pieces which are oppositely arranged in a grid-shaped crossed manner, and the distance between the electrode arrays of the double electrodes is less than or equal to 0.1 mm, so that the test surfaces of the double electrodes have a good conduction technical effect under the action of a discontinuous thin liquid film, and the characteristic simulation of a metal / solution interface process and non-uniform and discontinuous electrochemical parameters is realized.

Description

Technical Field

[0001] The invention relates to the technical field of electrochemical corrosion, and in particular to an in-situ testing system and method for electrochemical corrosion of a carbon dioxide-rich phase. Background Art

[0002] Carbon dioxide is an acidic gas. When it dissolves in water, it forms a carbonate solution, which can cause serious corrosion damage to metal materials. At the same time, carbon dioxide is one of the main greenhouse gases, and its emission has led to global climate change, which has become a consensus of the international community.

[0003] Under the vision of achieving carbon neutrality in my country, the field of carbon dioxide capture, utilization and storage (CCUS) faces huge demands, and pipeline transportation, as a large-capacity, low-cost, stable and continuous transportation method, is the key link to transport carbon dioxide from the capture site to the storage site or utilization site. In the process of pipeline transportation, in order to improve transportation efficiency and reduce costs, carbon dioxide is usually compressed to a high-pressure state, that is, it is transported in a supercritical state or dense phase state. The carbon dioxide transported by pipeline often contains a certain amount of water. Under certain environmental conditions, the water phase precipitates on the surface of the pipe wall to form a thin liquid film, which then dissolves the carbon dioxide to form a corrosive electrolyte solution, causing serious corrosion to the pipeline, threatening the safe operation of pipeline transportation and the smooth implementation of CCUS.

[0004] Different from the corrosion problem of conventional CO2-containing oil and gas pipelines, in CO2 transmission pipelines, CO2 is the main phase, i.e., the CO2-rich phase; while water is the impurity phase, which precipitates on the metal surface to form a thin liquid film. At this time, the metal / solution interface process and electrochemical parameters are uneven and discontinuous. This discontinuous feature makes it difficult to conduct in-situ testing and characterization of the electrochemical corrosion behavior of the pipe wall material under the action of the CO2-rich phase thin liquid film using a conventional three-electrode system. Existing test methods and devices usually immerse the test electrode in a CO2-saturated solution, which is very different from the thin liquid film solution system in the CO2-rich phase. Such a corrosion environment cannot truly simulate the corrosion behavior of the material under the action of the CO2-rich phase thin liquid film. Summary of the invention

[0005] In order to solve the problems existing in the above-mentioned prior art, the present invention provides an in-situ testing system and method for electrochemical corrosion in a carbon dioxide-rich phase, including the following specific technical solutions:

[0006] A carbon dioxide-rich phase electrochemical corrosion in-situ testing system, comprising a carbon dioxide pressurizing device, a reaction kettle, a heating device, a first test piece, and an electrochemical analyzer;

[0007] The carbon dioxide pressurizing device is used to prepare pressurized carbon dioxide and is fixedly connected to the reactor via a delivery pipe to inject pressurized carbon dioxide into the reactor;

[0008] The reactor is used to provide and maintain a stable set temperature and pressure environment in the reactor, the set temperature in the reactor is greater than 31.1°C, and the set pressure is greater than 7.38MPa;

[0009] The heating device comprises a temperature control system and a heating jacket, wherein the heating jacket covers the reactor, and the reactor is heated by the heating jacket under the control of the temperature control system;

[0010] The first test piece is arranged inside the reactor, and two of the first test pieces form a double electrode, which is electrically connected to an electrochemical tester outside the reactor through a wire.

[0011] Furthermore, the first test piece includes a first metal strip, a plurality of second metal strips, and a third metal strip; the third metal strip is arranged at the end of the first metal strip and is arranged vertically and equidistantly with the second metal strip on the same side of the first metal strip.

[0012] Furthermore, two of the first test pieces arranged in a relative grid-like cross pattern form a double electrode, and the second metal strips of the double electrode are arranged at equal intervals and staggered to form an electrode array.

[0013] Furthermore, the distance between adjacent second metal strips of the dual electrodes is ≤0.1 mm; the dual electrodes are encapsulated using epoxy resin; the encapsulated dual electrodes are polished to expose the dual electrode test surface, and the dual electrode test surface is polished to a roughness between 0.01 μm and 0.08 μm.

[0014] Furthermore, the thickness of the first test piece is 2 mm; the length of the first metal strip is 30 mm, and the width is 2 mm; the length of the second metal strip is 18 mm, and the width is 0.8 mm; and the length of the third metal strip is 18 mm, and the width is 5 mm.

[0015] Furthermore, the double electrodes are fixedly arranged at the upper end of the reactor through a polytetrafluoroethylene tube; the wires are buried in the polytetrafluoroethylene tube and are respectively connected to the third metal strips located at both ends of the double electrodes.

[0016] Furthermore, the in-situ test system also includes a second test piece; the second test piece is provided in plurality and is suspended inside the reactor by a polytetrafluoroethylene bracket.

[0017] Furthermore, a motor is arranged above the reactor, the output shaft of the motor is connected to a stirring shaft, the stirring shaft penetrates into the interior of the reactor, and a stirring blade is arranged at the end of the stirring shaft; the stirring blade rotates forward and / or reversely at a set frequency, so as to simulate the flow condition of carbon dioxide when being transported in an actual pipeline in the reactor.

[0018] Furthermore, two of the first test pieces are arranged in concentric circles or mosquito coils to form a double electrode, and the distance between the electrode test surfaces of the double electrode is ≦0.1 mm.

[0019] An in-situ testing method for electrochemical corrosion in a carbon dioxide-rich phase, using the above-mentioned in-situ testing system, comprises the following steps:

[0020] S1, adding deionized water into the reactor, wherein the volume of the deionized water is set so that the highest liquid level does not touch any part of the first test piece and the second test piece;

[0021] S2, the surfaces of the dual electrodes other than the test surface are encapsulated with epoxy resin. Before encapsulation, the third metal strips at both ends of the test surface are connected to the wires and led out; after encapsulation, the dual electrode test surface is polished step by step with water-abrasive sandpaper to the mirror surface, and then rinsed with deionized water and anhydrous ethanol respectively, dried with cold air, and placed in a dry environment for use;

[0022] S3, installing the packaged dual electrodes on the lid of the high-temperature and high-pressure reactor, and setting the dual electrodes in the reactor so that the dual electrode test surface faces downward;

[0023] The second test piece is suspended on a polytetrafluoroethylene bracket, and the second test piece is completely exposed above the liquid surface of deionized water;

[0024] S4, close the reactor, start the nitrogen booster pump, open the reactor exhaust valve, inject pressurized carbon dioxide into the reactor, and close the reactor exhaust valve after maintaining it for at least 60 minutes. When the pressure in the reactor is greater than 7.38 MPa, close the delivery pipe;

[0025] S5, start the temperature control system, heat the carbon dioxide in the reactor through the heating jacket, measure the temperature in the reactor through the temperature sensor, and control the temperature in the reactor to maintain greater than 31.1° C.;

[0026] S6, based on the data collected by the electrochemical analyzer, draw the polarization curve and AC impedance spectrum of the double electrode under the action of the thin liquid film rich in carbon dioxide phase;

[0027] After maintaining the test environment in the reactor for at least 24 hours, take out the second test piece, observe the corrosion state of the second test piece, and perform corrosion evaluation on the second test piece using analytical testing methods such as scanning electron microscopy and energy dispersive spectrometer;

[0028] Based on the collected dual-electrode polarization curves and AC impedance spectra, as well as the corrosion evaluation of the second test piece, the in-situ test analysis of the electrochemical corrosion of the carbon dioxide-rich phase was completed.

[0029] Based on the above technical solution, the in-situ testing system and method for electrochemical corrosion in a carbon dioxide-rich phase described in the present invention have the following beneficial effects:

[0030] 1. The dual electrode consists of two first test pieces arranged in a relative grid-like cross pattern. The second metal strips of the first test piece are arranged at equal intervals to form an electrode array. The spacing between adjacent second metal strips is ≤0.1mm, so that the dual electrode test surface can have a good conduction technical effect under the action of a discontinuous thin liquid film, and realize the simulation of the uneven and discontinuous characteristics of the metal / solution interface process and electrochemical parameters.

[0031] 2. Using epoxy resin to encapsulate the dual electrodes can ensure that the working electrode and the auxiliary electrode are insulated from each other, and the dual electrode test surface is polished to make the roughness of the dual electrode test surface between 0.01μm-0.08μm, achieving a mirror effect, and obtaining the technical effect of a smooth and flat surface and uniform structural organization of the dual electrode test surface.

[0032] 3. The first test piece and the second test piece are made of materials from the carbon dioxide transport pipeline at the operation site, realizing a true simulation of the transport pipeline. And the first test piece is set with detailed dimensions to obtain sufficient test area and strength.

[0033] 4. A dual-electrode test piece and a corrosion test piece are set in the reactor, which can collect the dual-electrode polarization curve and AC impedance spectrum through the electrochemical analyzer, and perform corrosion evaluation on the second test piece, so as to scientifically and effectively complete the in-situ test and analysis of the electrochemical corrosion of the carbon dioxide-rich phase, so as to provide technical guidance for the supercritical carbon dioxide pipeline transportation in the actual operation process.

[0034] 5. The carbon dioxide pressurizing device uses high-pressure nitrogen to drive the nitrogen booster pump to pressurize the carbon dioxide. Nitrogen is an inert gas, and there is no oil or other solvent attached to the nitrogen booster pump, thereby ensuring that the carbon dioxide entering the reactor remains pure.

[0035] 6. The temperature control system drives the heating jacket to heat the reactor. The temperature inside the reactor can be adjusted according to actual operating requirements and maintain a stable set temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 : Schematic diagram of the overall structure of the test system in the embodiment;

[0037] Figure 2 : Schematic diagram of the double electrode structure in the embodiment;

[0038] Figure 3 : Schematic diagram of double electrode packaging in the embodiment;

[0039] Figure 4 : Schematic diagram of the measurement results of the double-electrode electrochemical impedance spectroscopy after testing for 120 hours in the embodiment;

[0040] Figure 5 : Schematic diagram of the scanning electron microscope observation results of the hanging piece surface after testing for 120 hours in the embodiment.

[0041] Explanation of symbols

[0042] 101-carbon dioxide gas tank, 102-nitrogen booster pump, 103-high-pressure nitrogen gas tank, 104-delivery pipe, 105-first valve;

[0043] 201-reaction kettle, 202-motor, 203-stirring shaft, 204-stirring blade;

[0044] 301-temperature control system, 302-heating jacket 302;

[0045] 4-first test piece, 401-first metal strip, 402-second metal strip, 403-third metal strip, 404-epoxy resin, 405-polytetrafluoroethylene tube;

[0046] 5-second test piece, 501-polytetrafluoroethylene support;

[0047] 6-Electrochemical analyzer;

[0048] 701 - tail gas collection device, 702 - air pipe, 703 - second valve. DETAILED DESCRIPTION

[0049] It should be noted that:

[0050] 1. Certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that technicians may use different terms to refer to the same component. This specification and claims do not use the difference in terms as a way to distinguish components, but use the difference in the functions of the components as the criterion for distinction.

[0051] 2. Unless otherwise clearly specified and limited, the terms "installation", "setting", "connection", etc. should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0052] 3. Unless otherwise defined, technical or scientific terms used in the present disclosure should have the common meanings understood by persons having ordinary skills in the field to which the present disclosure belongs.

[0053] The following is combined with Figure 1 -Attached Figure 5 , the present invention is described in detail by way of embodiments.

[0054] This embodiment describes an in-situ testing system for electrochemical corrosion in a carbon dioxide-rich phase, comprising:

[0055] Carbon dioxide pressurizing device, reactor 201 , heating device, first test piece 4 , electrochemical analyzer 6 .

[0056] The carbon dioxide pressurizing device is used to prepare pressurized carbon dioxide, and is fixedly connected to the reactor 201 through the delivery pipe 104 to inject the pressurized carbon dioxide into the reactor 201. The delivery pipe 104 is provided with a first valve 105 for controlling the flow of carbon dioxide in the delivery pipe 104.

[0057] The carbon dioxide pressurizing device includes a carbon dioxide gas tank 101 , a nitrogen booster pump 102 , and a high-pressure nitrogen gas tank 103 .

[0058] The high-pressure nitrogen tank 103, the carbon dioxide tank 101, and the delivery pipe 104 are sequentially connected to the driving gas inlet, the air inlet, and the air outlet of the nitrogen booster pump 102, and the nitrogen drives the nitrogen booster pump 102 to operate and output carbon dioxide at a set pressure. The set pressure should be greater than 7.38MPa.

[0059] The reactor 201 is a high-temperature autoclave, which is used to provide and maintain a stable temperature and pressure environment in the reactor. The bearing temperature range of the reactor 201 is set to room temperature-150°C, and the bearing pressure is set to normal pressure-20MPa.

[0060] A motor 202 is arranged above the reactor 201, and the output shaft of the motor is connected to a stirring shaft 203, which penetrates into the reactor 201, and a stirring blade 204 is arranged at the end of the stirring shaft 203. The stirring inside the reactor 201 is arranged to simulate the flow condition when the pipeline transports carbon dioxide.

[0061] The heating device includes a temperature control system 301 and a heating jacket 302. The heating jacket 302 covers the reactor 201. Under the control of the temperature control system 301, the reactor 201 is heated by the heating jacket 302, so that the temperature inside the reactor 201 is increased and stabilized at a set temperature. The set temperature should be greater than 31.1°C.

[0062] The first test piece 4 is made of metal. In this embodiment, the first test piece 4 is made of a carbon dioxide transport pipeline at the operation site to achieve a true simulation of the transport pipeline.

[0063] The first test piece 4 includes a first metal strip 401, a plurality of second metal strips 402, and a third metal strip 403. The third metal strip 403 is disposed at the end of the first metal strip 401 and is vertically disposed on the same side of the first metal strip 401 with equal spacing from the second metal strip 402.

[0064] In order to obtain the technical effect of sufficient test area and strength, the present embodiment sets the size of the first test piece 4 as follows: the thickness of the first test piece 4 is 2 mm; the length of the first metal strip 401 is 30 mm and the width is 2 mm; the length of the second metal strip 402 is 18 mm and the width is 0.8 mm; the length of the third metal strip 403 is 18 mm and the width is 5 mm.

[0065] Two first test pieces 4 arranged in a grid-like cross pattern form a double electrode, including a working electrode and an auxiliary electrode, and the auxiliary electrode also serves as a reference electrode.

[0066] The second metal strips 402 of the dual electrodes are arranged at equal intervals to form an electrode array, and in order to obtain the technical effect of good conduction of the dual electrode test surface under the action of a discontinuous thin liquid film, the spacing between adjacent second metal strips 402 of the dual electrodes is ≤0.1 mm.

[0067] To ensure that the working electrode and the auxiliary electrode are insulated from each other, the double electrodes are packaged with epoxy resin 404. The packaged double electrodes are polished to expose the double electrode test surface. In order to obtain the technical effect of smooth and flat electrode surface and uniform structure, the double electrode test surface is further polished to make the roughness of the double electrode test surface between 0.01μm-0.08μm, achieving a mirror effect.

[0068] The double electrode is fixedly arranged at the upper end of the reactor 201 through a polytetrafluoroethylene tube 405, and is electrically connected to the electrochemical analyzer 6 outside the reactor 201 through a wire. The wire is buried inside the polytetrafluoroethylene tube 405, and the connection method between the wire and the double electrode is soldering. In order to obtain a technical effect of sufficient welding strength, when the wire is connected to the double electrode, the third metal strip 403 of the working electrode and the third metal strip 403 of the auxiliary electrode located at both ends of the double electrode test surface are connected respectively.

[0069] The second test piece 5 is made of metal. In this embodiment, the second test piece 5 is also made of materials taken from the carbon dioxide transportation pipeline at the operation site, so as to achieve a true simulation of the transportation pipeline.

[0070] The second test pieces 5 are arranged in plurality and are suspended inside the reaction vessel 201 via a polytetrafluoroethylene bracket 501 .

[0071] In this embodiment, the system further includes an exhaust gas collection device 701, which is connected to the exhaust valve of the reactor 201 via an air pipe 702, and a second valve 703 is provided on the air pipe 702; an alkaline solution is stored in the device for collecting and neutralizing carbon dioxide escaping or discharged from the reactor 201.

[0072] In addition, the working electrode and auxiliary electrode in the dual electrode can also be designed to be arranged in the form of concentric rings or mosquito coils. In order to obtain the technical effect of good conduction between the working electrode and the auxiliary electrode test surfaces under the action of a discontinuous thin liquid film, the spacing between the two electrode test surfaces should be ≤0.1mm.

[0073] According to the system described above, this embodiment also describes an in-situ testing method for electrochemical corrosion in a carbon dioxide-rich phase, comprising the following steps:

[0074] S1, select a high-temperature and high-pressure reactor 201 with a working volume of 1.6 L, add deionized water into the reactor 201, and set the amount or volume of the deionized water so that the highest liquid level does not touch any part of the first test piece 4 and the second test piece 5.

[0075] S2, the other surfaces of the dual electrodes except the test surface are encapsulated by epoxy resin 404. Before encapsulation, the third metal strips 403 located at both ends of the test surface are connected to the wires and led out; after encapsulation, the dual electrode test surface is polished step by step by water-abrasive sandpaper to the mirror surface, and then rinsed with deionized water and anhydrous ethanol respectively, dried with cold wind and placed in a dry environment for use;

[0076] S3, installing the packaged dual electrodes on the lid of the high-temperature and high-pressure reactor, and setting the dual electrodes in the reactor 201 with the dual electrode test surface facing downward, which can obtain the corrosion effect of the flowing thin liquid film;

[0077] The second test piece 5 is suspended on the polytetrafluoroethylene support 501 , and the second test piece 5 is completely exposed above the liquid surface of the deionized water.

[0078] S4, close the reactor 201, start the nitrogen booster pump 102, open the reactor exhaust valve, inject pressurized carbon dioxide into the reactor, and close the reactor exhaust valve after maintaining for at least 60 minutes. This operation method can discharge the residual gas in the reactor and the air dissolved in the deionized water. The reactor pressure gauge displays the air pressure in the reactor 201 in real time. When the air pressure is greater than 7.38MPa, close the delivery pipe 104.

[0079] S5, start the temperature control system 301, heat the carbon dioxide in the reactor through the heating jacket 302, measure the temperature in the reactor through the temperature sensor, and control the temperature in the reactor to maintain greater than 31.1°C.

[0080] S6, drawing the polarization curve and AC impedance spectrum of the double electrode under the action of the thin liquid film of the carbon dioxide-rich phase according to the data collected by the electrochemical analyzer 6;

[0081] After maintaining the test environment in the reactor for at least 24 hours, take out the second test piece 5, observe the corrosion state of the second test piece 5, and perform corrosion evaluation on the second test piece 5 using analysis and testing methods such as scanning electron microscopy and energy dispersive spectrometer;

[0082] Based on the collected dual-electrode polarization curve and AC impedance spectrum, as well as the corrosion evaluation of the second test piece 5, the in-situ test analysis of the electrochemical corrosion of the carbon dioxide-rich phase is completed.

[0083] The method described in this embodiment can also realize in-situ corrosion test analysis of thin liquid films after adding corrosion inhibitors to the carbon dioxide-rich phase, and further evaluate the effect of the corrosion inhibitors.

[0084] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A carbon dioxide-rich phase electrochemical corrosion in-situ testing system, characterized in that: include A carbon dioxide pressurizing device, a reaction kettle, a heating device, a first test piece, and an electrochemical analyzer; The carbon dioxide pressurizing device is used to prepare pressurized carbon dioxide and is fixedly connected to the reactor via a delivery pipe to inject pressurized carbon dioxide into the reactor; The reactor is used to provide and maintain a stable set temperature and pressure environment in the reactor, the set temperature in the reactor is greater than 31.1°C, and the set pressure is greater than 7.38MPa; The heating device comprises a temperature control system and a heating jacket, wherein the heating jacket covers the reactor, and the reactor is heated by the heating jacket under the control of the temperature control system; The first test piece is arranged inside the reactor, and two of the first test pieces form a double electrode, which is electrically connected to an electrochemical tester outside the reactor through a wire.

2. The in-situ testing system for electrochemical corrosion in a carbon dioxide-rich phase according to claim 1, characterized in that: The first test piece includes a first metal strip, a plurality of second metal strips, and a third metal strip; the third metal strip is arranged at the end of the first metal strip and is arranged vertically and equidistantly with the second metal strip on the same side of the first metal strip; The two first test pieces arranged in a relative grid-like cross pattern form a double electrode, and the second metal strips of the double electrode are arranged at equal intervals and staggered to form an electrode array.

3. The in-situ testing system for electrochemical corrosion in a carbon dioxide-rich phase according to claim 2, characterized in that: The distance between adjacent second metal strips of the dual electrodes is ≤0.1 mm; The double electrodes are encapsulated with epoxy resin; The packaged dual electrodes are ground until the dual electrode test surface is exposed, and the dual electrode test surface is polished until its roughness is between 0.01 μm and 0.08 μm.

4. A carbon dioxide-rich phase electrochemical corrosion in-situ testing system according to any one of claims 2 or 3, characterized in that: The thickness of the first test piece is 2 mm; The first metal strip has a length of 30 mm and a width of 2 mm; The second metal strip has a length of 18 mm and a width of 0.8 mm; The third metal strip has a length of 18 mm and a width of 5 mm.

5. A carbon dioxide-rich phase electrochemical corrosion in-situ testing system according to claim 2 or 3, characterized in that: The double electrodes are fixedly arranged at the upper end of the reactor through a polytetrafluoroethylene tube; The wire is buried in the polytetrafluoroethylene tube and is respectively connected to the third metal strips located at both ends of the double electrodes.

6. A carbon dioxide-rich phase electrochemical corrosion in-situ testing system according to any one of claims 1 to 5, characterized in that: The in-situ test system also includes a second test piece; the second test piece is arranged in plurality and is suspended inside the reactor by a polytetrafluoroethylene bracket.

7. A carbon dioxide-rich phase electrochemical corrosion in-situ testing system according to any one of claims 1 to 5, characterized in that: A motor is arranged above the reactor, and an output shaft of the motor is connected to a stirring shaft. The stirring shaft penetrates into the reactor, and a stirring blade is arranged at the end of the stirring shaft; the stirring blade rotates forward and / or reversely at a set frequency, so as to simulate the flow condition of carbon dioxide when being transported in an actual pipeline in the reactor.

8. A carbon dioxide-rich phase electrochemical corrosion in-situ testing system according to any one of claims 1 to 5, characterized in that: The carbon dioxide pressurizing device includes a carbon dioxide gas tank, a nitrogen booster pump, and a high-pressure nitrogen tank; the high-pressure nitrogen tank, the carbon dioxide gas tank, and the delivery pipe are sequentially connected to the driving gas inlet, the air inlet, and the air outlet of the nitrogen booster pump, and the nitrogen drives the nitrogen booster pump to operate and output carbon dioxide under a set pressure.

9. The in-situ testing system for electrochemical corrosion in a carbon dioxide-rich phase according to claim 1, characterized in that: The two first test pieces are arranged in concentric circles or mosquito coils to form a double electrode, and the distance between the electrode test surfaces of the double electrode is ≤0.1 mm.

10. An in-situ testing method for electrochemical corrosion in a carbon dioxide-rich phase, using the in-situ testing system according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1, adding deionized water into the reactor, wherein the volume of the deionized water is set so that the highest liquid level does not touch any part of the first test piece and the second test piece; S2, the surfaces of the dual electrodes other than the test surface are encapsulated with epoxy resin. Before encapsulation, the third metal strips at both ends of the test surface are connected to the wires and led out; after encapsulation, the dual electrode test surface is polished step by step with water-abrasive sandpaper to the mirror surface, and then rinsed with deionized water and anhydrous ethanol respectively, dried with cold air, and placed in a dry environment for use; S3, installing the packaged dual electrodes on the lid of the high-temperature and high-pressure reactor, and setting the dual electrodes in the reactor so that the dual electrode test surface faces downward; The second test piece is suspended on a polytetrafluoroethylene bracket, and the second test piece is completely exposed above the liquid surface of deionized water; S4, close the reactor, start the nitrogen booster pump, open the reactor exhaust valve, inject pressurized carbon dioxide into the reactor, and close the reactor exhaust valve after maintaining it for at least 60 minutes. When the pressure in the reactor is greater than 7.38 MPa, close the delivery pipe; S5, start the temperature control system, heat the carbon dioxide in the reactor through the heating jacket, measure the temperature in the reactor through the temperature sensor, and control the temperature in the reactor to maintain greater than 31.1° C.; S6, based on the data collected by the electrochemical analyzer, draw the polarization curve and AC impedance spectrum of the double electrode under the action of the thin liquid film rich in carbon dioxide phase; After maintaining the test environment in the reactor for at least 24 hours, take out the second test piece, observe the corrosion state of the second test piece, and perform corrosion evaluation on the second test piece using analytical testing methods such as scanning electron microscopy and energy dispersive spectrometer; Based on the collected dual-electrode polarization curves and AC impedance spectra, as well as the corrosion evaluation of the second test piece, the in-situ test analysis of the electrochemical corrosion of the carbon dioxide-rich phase was completed.

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