Sample structure and experimental device for supercritical carbon dioxide corrosion test

Abstract

The invention relates to the technical field of experimental equipment, and discloses a sample structure for supercritical carbon dioxide corrosion testing and an experimental device.The sample structure comprises a sample body and a clamping end, an axially-penetrating hollow cavity is formed in the sample body, and the hollow cavity is used for introducing a high-pressure flowing carbon dioxide medium; the clamping ends are located at the two ends of the sample, clamping steps are arranged on the outer surfaces of the clamping ends, conical end faces are arranged at the ends of the clamping ends, the clamping steps are used for bearing tensile loads, and the conical end faces are used for forming mechanical extrusion sealing with a sealing joint. According to the sample structure provided by the invention, the technical bottlenecks of simulation distortion, out-of-control leakage and short service life of equipment existing in the supercritical carbon dioxide corrosion test field for a long time are overcome through the collaborative design of the axially penetrating hollow cavity, the clamping step and the conical end surface; and a high-fidelity, low-cost and long-period experiment basis is provided for material selection of key components of the supercritical carbon dioxide power generation system.

Description

Technical Field

[0001] The present application relates to the technical field of experimental equipment, for example, to an experimental device for evaluating carbon dioxide flow accelerated corrosion and stress corrosion of materials. Background Art

[0002] In supercritical carbon dioxide (S-CO2) power generation systems, key components (such as turbine blades and heat exchange tubes) are exposed to high-temperature, high-pressure (>31°C, >7.4MPa) and high-speed flow supercritical carbon dioxide environments for a long time. They face the synergistic effects of flow-accelerated corrosion (FAC) and stress corrosion (SCC), which significantly increases the risk of material failure.

[0003] However, existing experimental devices suffer from a single function. Existing equipment (such as CN112285011B and CN117347250A) can only test uniform corrosion or FAC and cannot simultaneously apply mechanical loads to evaluate SCC performance. Dedicated SCC devices (such as CN117571588A) can apply stress but lack the ability to simulate high-velocity corrosion environments.

[0004] In summary, existing technologies are unable to realize switching tests between FAC (no load) and SCC (loaded) on a single sample, resulting in low experimental efficiency.

[0005] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of this application, and therefore may include information that does not constitute prior art known to ordinary technicians in this field. Summary of the Invention

[0006] In order to provide a basic understanding of some aspects of the disclosed embodiments, a brief summary is given below. The summary is not an extensive review, nor is it intended to identify key / critical elements or delineate the scope of protection of these embodiments, but rather serves as a prelude to the detailed description that follows.

[0007] The embodiments of the present disclosure provide a sample structure and experimental device for supercritical carbon dioxide corrosion testing, which can be applied to the detection and analysis of materials in terms of flow-accelerated corrosion and stress corrosion.

[0008] In some embodiments, the sample structure includes: a sample body, wherein an axially penetrating hollow cavity is provided inside the sample body, wherein the hollow cavity is used to introduce a high-pressure flowing carbon dioxide medium; The clamping end is located at both ends of the sample, and its outer surface is provided with a clamping step. The end of the clamping end is provided with a tapered end face. The clamping step is used to bear the tensile load, and the tapered end face is used to form a mechanical extrusion seal with the sealing joint.

[0009] Optionally, the tapered end face and the sealing joint are sealed by mechanical extrusion.

[0010] Optionally, the cone angle of the conical end face is 15° to 60°.

[0011] In some embodiments, the experimental apparatus for supercritical carbon dioxide corrosion testing comprises: The sample structure used for supercritical carbon dioxide corrosion testing as described above; A CO2 circulation loop connected to the hollow cavity of the sample structure to form an independent closed flow path; a high-temperature autoclave with a built-in inert gas protective layer covering the outer surface of the sample structure; A mechanical loading system is used to connect the fixtures of the sample structure and apply tensile load.

[0012] Optionally, the experimental device further comprises a sealing joint for connecting the sample structure with the CO2 circulation loop; The inner side surface of the sealing joint is provided with an internal thread for cooperating with the clamping end of the sample structure; and / or, a right-angle step structure is provided inside the sealing joint for cutting into the tapered end surface to achieve sealing.

[0013] Optionally, the experimental device also includes a clamp, which includes a sample upper pressing plate and a sample lower pressing plate, and the middle parts of the sample upper pressing plate and the sample lower pressing plate are both split structures, the sample upper pressing plate abuts against the lower surface of the clamping step at the upper part of the clamping end, and the sample lower pressing plate abuts against the upper surface of the clamping step at the lower part of the clamping end.

[0014] Optionally, the fixture further comprises: The upper end surface of the sample support stand is located above the clamping step on the upper part of the clamping end and is connected to the sample upper pressing piece through the upper clamp fastening bolts; The lower clamp support base is located below the clamping step at the lower part of the clamping end and is connected to the sample lower pressing plate through the lower clamp fastening bolts.

[0015] Optionally, the CO2 circulation loop includes a gas booster pump, a preheater, a cooler, and a filter, and is isolated from the internal space of the high-temperature and high-pressure autoclave.

[0016] Optionally, the inert gas protective layer is formed by argon gas introduced into a high-temperature autoclave.

[0017] Optionally, the tensile shaft of the mechanical loading system is connected to the lower fixture support base through a threaded connection, and the entire system is placed outside the high-temperature autoclave.

[0018] The sample structure and experimental device for supercritical carbon dioxide corrosion testing provided by the embodiments of the present disclosure can achieve the following technical effects: The sample structure provided by the present invention achieves the following effects through the coordinated design of the axially penetrating hollow cavity, the clamping step, and the tapered end face: Improved simultaneous testing efficiency: The hollow chamber allows high-pressure CO2 to flow through the sample at high speed, accurately simulating flow-accelerated corrosion (FAC) under no-load conditions. Once the clamping step is loaded with tensile stress, the system can switch directly to stress corrosion corrosion (SCC) testing within the same chamber. This design eliminates the cumbersome process of changing samples or equipment required in traditional solutions, improving testing equipment utilization.

[0019] Improved sealing reliability: The clamping end of the sample structure is threadedly connected to the sealing structure. As the sealing structure is screwed in, the internal step of the sealing structure gradually embeds into the tapered end face. The tapered end face undergoes plastic deformation, creating a closed space between the tapered end face and the sealing structure, thus achieving a sealing effect. At the same time, the clamping step isolates the tensile load outside the sealing interface, ensuring zero relative displacement of the sealing surface during loading. This can eliminate the risk of gas leakage under high-pressure loading conditions.

[0020] Optimization of the entire equipment life and economy: The micro-flow path design of the hollow cavity significantly reduces the CO2 consumption in a single test compared to the traditional solution of filling the entire reactor with supercritical carbon dioxide. More importantly, the CO2 is strictly restricted to flow inside the sample, avoiding contact with the high-temperature and high-pressure reactor. Combined with the anti-corrosion effect of the argon protective layer on the reactor body, it can extend the service life of the equipment and significantly reduce operation and maintenance costs.

[0021] The sample structure, with its triple innovations of "cavity simulation + step decoupling + conical sealing", has overcome the long-standing technical bottlenecks of "simulation distortion, uncontrolled leakage, and short equipment life" in the field of supercritical carbon dioxide corrosion testing. It provides a high-fidelity, low-cost, and long-cycle experimental basis for the selection of key components of supercritical carbon dioxide power generation systems, which is of great significance to ensuring the safe service of energy equipment.

[0022] Furthermore, the sample structure's clamping end features a clamping step to absorb the forces applied during stress corrosion testing. This design transfers most of the tensile load from the sealing interface (tapered end face) to the fixture press. This design maintains near-zero stress in the sealing area throughout the test, effectively avoiding the micro-leakage issues associated with sample deformation in traditional solutions and significantly improving sealing reliability under high-pressure supercritical conditions.

[0023] The above general description and the following description are exemplary and explanatory only and are not intended to limit the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] One or more embodiments are exemplarily described by corresponding drawings. These exemplary descriptions and drawings do not limit the embodiments. Elements with the same reference numerals in the drawings are shown as similar elements. The drawings do not constitute a scale limitation. In addition, Figure 1 Schematic diagram of an experimental device for supercritical carbon dioxide corrosion testing provided by an embodiment of the present disclosure; Figure 2 is a schematic cross-sectional view of a sample structure fixture provided by an embodiment of the present disclosure; Figure 3 This is a schematic diagram of a structure for supercritical carbon dioxide corrosion testing provided by an embodiment of the present disclosure; Figure 4 This is a schematic diagram of a sample structure provided by an embodiment of the present disclosure and its cooperation with a sealing joint.

[0025] Reference numerals: 1. Cooler; 2. Chiller outlet pipe; 3. Circulating chiller; 4. Chiller return pipe; 5. Air outlet pipe; 6. Second pressure gauge; 7. Argon cylinder; 8. Argon inlet pipe; 9. Mechanical loading mechanism; 10. High-temperature autoclave base; 11. Inlet pipe; 12. Preheater; 13. First pressure gauge; 14. Stop valve; 15. Gas booster pump; 16. Gas cylinder; 17. Waste gas treatment device; 18. Gas storage tank; 19. Gas composition detector; 20. Third pressure gauge; 21. Back pressure valve; 22. Secondary filter; 23. Primary filter; 2 4. Argon waste gas treatment device; 25. Argon gas outlet pipe; 26. Sample support stand; 27. High-temperature and high-pressure autoclave; 28. Heating plate; 29. ​​Sample body; 30. Sample upper clamp; 31. Sample lower clamp; 32. Upper sealing joint; 33. Clamping end; 34. Sample lower pressure plate; 35. Upper clamp fastening bolt; 36. Upper end face of sample support stand; 37. Sample upper pressure plate; 38. Lower clamp fastening bolt; 39. Lower clamp support base; 40. Lower sealing joint; 41. Tensile shaft; 42. Conical end face; 43. Clamping step; 44. Hollow cavity. DETAILED DESCRIPTION

[0026] In order to be able to understand the features and technical content of the embodiments of the present disclosure in more detail, the implementation of the embodiments of the present disclosure is described in detail below in conjunction with the accompanying drawings. The accompanying drawings are for reference only and are not used to limit the embodiments of the present disclosure. In the following technical description, for the sake of convenience of explanation, a full understanding of the disclosed embodiments is provided through multiple details. However, one or more embodiments can still be implemented without these details. In other cases, to simplify the drawings, well-known structures and devices can be simplified for display.

[0027] In the description and claims of the embodiments of the present disclosure, as well as in the accompanying drawings, the terms "first," "second," and the like are used to distinguish similar items and are not necessarily used to describe a particular order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate to describe the embodiments of the present disclosure herein. In addition, the terms "including," "having," and any variations thereof are intended to cover non-exclusive inclusions.

[0028] In the embodiments of the present disclosure, the terms "upper", "lower", "inside", "middle", "outside", "front", "back" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. These terms are mainly intended to better describe the embodiments of the present disclosure and their embodiments, and are not intended to limit the indicated devices, elements or components to having a specific direction, or to be constructed and operated in a specific direction. Moreover, in addition to being used to indicate directions or positional relationships, some of the above terms may also be used to indicate other meanings. For example, the term "upper" may also be used to indicate a certain dependency or connection relationship in certain circumstances. For those of ordinary skill in the art, the specific meanings of these terms in the embodiments of the present disclosure can be understood according to specific circumstances.

[0029] Furthermore, the terms "disposed," "connected," and "fixed" should be interpreted broadly. For example, "connected" can mean a fixed connection, a removable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be a direct connection, an indirect connection through an intermediary, or an internal connection between two devices, elements, or components. Those skilled in the art will understand the specific meanings of these terms in the embodiments of this disclosure based on the specific circumstances.

[0030] Unless otherwise stated, the term "plurality" means two or more.

[0031] In the embodiment of the present disclosure, the character " / " indicates that the preceding and following objects are in an "or" relationship. For example, A / B means: A or B.

[0032] The term "and / or" describes an association between objects, indicating that three relationships can exist. For example, A and / or B means: A or B, or A and B.

[0033] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present disclosure can be combined with each other.

[0034] Combine Figure 2 、 3 As shown, an embodiment of the present disclosure provides a sample structure for supercritical carbon dioxide corrosion testing, including a sample body 29 and a clamping end 33 .

[0035] The sample body 29 has an axially penetrating hollow cavity 44 disposed therein, and the hollow cavity 44 is used to allow high-pressure flowing carbon dioxide medium to flow; The clamping end 33 is located at both ends of the sample, and its outer surface is provided with a clamping step 43. The end of the clamping end 33 is provided with a tapered end face 42. The clamping step 43 is used to bear the tensile load, and the tapered end face 42 is used to form a mechanical extrusion seal with the sealing joint.

[0036] It is understood that the sample body 29 and the clamping end 33 can be an integrated structure, and the clamping end 33 can also be a structure that is sleeved outside the sample body 29 and located at both ends of the sample body 29. In this application, the sample body 29 and the clamping end 33 are preferably an integrated structure.

[0037] Optionally, the tapered end face 42 and the sealing joint form a seal through mechanical extrusion.

[0038] Optionally, the cone angle of the conical end surface 42 is 15° to 60°.

[0039] The sample structure for supercritical carbon dioxide corrosion testing provided by the embodiment of the present disclosure has a hollow sample body 29, and the high-pressure CO2 gas injected by the gas booster pump 15 flows through the interior of the sample at a high speed. When the sample is loaded without using a mechanical loading device, the flow-accelerated corrosion performance can be studied, and the stress corrosion performance can be studied during loading; the upper and lower clamping ends 33 of the sample are both processed with steps for fixing and bearing tensile stress; the end face of the sample is conical, and the ends of the air inlet pipe 11 and the air outlet pipe are both connected to a sealing joint, which is connected to the top of the sample clamping end 33 through a thread, and the right-angle step inside the sealing joint cuts into the conical end face 42 of the sample to form a seal through mechanical extrusion deformation, thereby realizing quick loading and unloading and sealing (similar to the form of a ferrule joint).

[0040] In summary, by setting an axially penetrating hollow cavity 44 inside the sample body 29, dual use of one cavity can be achieved. High-pressure CO2 is introduced into the hollow cavity 44 to realize the no-load flow accelerated corrosion (FAC) test, and after the clamping step 43 bears the tensile stress, it can be directly switched to the stress corrosion (SCC) test in the same cavity, which significantly improves the experimental efficiency.

[0041] The cone angle range of 15°–60° balances sealing strength and assembly tolerance, avoiding leakage failure due to angle deviation.

[0042] Combine Figure 1 As shown, the embodiment of the present disclosure provides an experimental device for supercritical carbon dioxide corrosion testing, comprising: The sample structure used for supercritical carbon dioxide corrosion testing as described above; A CO2 circulation loop is connected to the hollow cavity 44 of the sample structure to form an independent closed flow path; a high-temperature autoclave 27 with a built-in inert gas protective layer covering the outer surface of the sample structure; A mechanical loading system is used to connect the fixtures of the sample structure and apply tensile load.

[0043] It can be understood that the CO2 circulation loop is connected to the sample body 29 through the pipeline and the sample fixture, forming an independent closed flow path for providing high-speed circulating CO2 gas inside the sample; the CO2 circulation and control system includes an air inlet pipeline 11, a gas booster pump 15, a stop valve 14, a pressure gauge, a preheater 12, an air outlet pipeline 5, a cooler 1, a filter, a back pressure valve 21, a gas composition detector 19, a gas storage tank 18, an exhaust gas treatment device 17, a CO2 cylinder 16, etc.; the passage order is: CO2 cylinder 16 → gas storage tank 18 → gas booster pump 15 → stop valve 14 → first pressure gauge 13 → preheater 12 → sample lower fixture 31 → sample body 29 → sample upper fixture 30 → second pressure gauge 6 → cooler 1 → primary and secondary filters 23, 22 → back pressure valve 21 → third pressure gauge 20 → gas composition detection and purification and drying device → gas storage tank 18.

[0044] The primary and secondary filters 23 and 22 are used to filter out corrosion products that may be carried in the high-speed CO2 gas.

[0045] In this way, the CO2 circulation loop connects to the sample through a micro-flow path (hollow cavity), which significantly reduces the gas consumption of a single test and intercepts corrosion products through a double-stage filter to protect downstream equipment.

[0046] Optionally, the inert gas protective layer is formed by argon gas introduced into the high-temperature autoclave 27 .

[0047] Understandably, traditional methods require the entire autoclave to be filled with supercritical carbon dioxide, resulting in long-term exposure of the autoclave to corrosive media, leading to seal failure and structural safety hazards. Furthermore, during high-temperature testing, the sample's outer surface is exposed to an oxygen-containing environment (such as air). High-temperature oxidation can obscure the true SCC crack morphology, distorting the data. The inert gas protective layer employed in this application, specifically an argon protective layer, covers the sample's outer surface, reducing the oxygen content and minimizing the interference of high-temperature oxidation on the sample's SCC performance evaluation.

[0048] The experimental device for supercritical carbon dioxide corrosion testing provided by the present invention achieves multiple breakthrough effects by integrating a sample structure, a partitioned CO2 circulation loop, an argon protective layer, and an externally isolated mechanical loading system: 1. Simultaneous FAC / SCC testing: A CO2 circulation loop connects the hollow cavity 44 in the sample. Under no-load conditions, the gas flow rate is adjusted (>15 m / s) to accurately simulate flow-accelerated corrosion (FAC). After applying a tensile load, the same device directly switches to stress corrosion corrosion (SCC) testing. A single sample loading allows for both key experiments, significantly improving efficiency compared to traditional separate equipment.

[0049] 2. The outer surface of the sample is covered with an argon protective layer to keep the oxygen content in the high-temperature autoclave 27 at a low level, thereby eliminating the influence of oxygen on the sample and obtaining a more accurate evaluation of the SCC performance (including crack morphology and mechanical properties, etc.) in a supercritical carbon dioxide environment.

[0050] 3. The CO2 circulation loop is strictly physically isolated from the internal space of the high-temperature autoclave 27 - the corrosive supercritical carbon dioxide only flows through the micro-flow path (hollow cavity) inside the sample, and the autoclave body is completely isolated from the corrosive medium by the inert gas layer, which can extend the service life of the equipment and reduce maintenance costs.

[0051] 4. The mechanical loading system 9 is placed outside the autoclave as a whole, and the stretching shaft 41 is connected to the lower fixture base 39 through a thread, completely out of the supercritical carbon dioxide environment, preventing supercritical carbon dioxide from corroding precision transmission components, thereby effectively reducing the equipment failure rate.

[0052] 5. The micro-flow path design of the hollow cavity in the sample structure significantly reduces the CO2 consumption in a single test, effectively reducing the test cost.

[0053] 6. Maintenance costs reduced by 80%: The dual-stage filter intercepts corrosion products >1 μm, protecting key components such as the booster pump, reducing equipment maintenance frequency and spare parts replacement costs.

[0054] In summary, this device, with its core features of "zonal protection" (CO2 internal flow / argon external protection) and "functional integration" (FAC-SCC integration), has for the first time overcome the three major contradictions in the field of supercritical CO2 corrosion testing: "simulation distortion, short equipment life, and high cost": Lifespan: Autoclave > 5 years (150% longer than traditional solutions); Fidelity: oxygen content <10 ppm; Economical: The overall cost of a single test is reduced by 90%, providing a zero-compromise, full-cycle, low-cost experimental benchmark platform for the selection of key components of supercritical CO2 power generation systems.

[0055] like Figure 4As shown, in some embodiments, the experimental device also includes a sealing joint for connecting the sample structure with the CO2 circulation loop, and the inner side surface of the sealing joint is provided with an internal thread for cooperating with the clamping end 33 of the sample structure; and / or, a right-angle step structure is provided inside the sealing joint for cutting into the conical end surface 42 to achieve sealing.

[0056] It can be understood that the inner side surface of the sealing joint is threadedly matched with the middle and lower side surface of the clamping end 33 of the sample structure. As the sealing joint is screwed in, the right-angle step structure inside the sealing joint cuts into the conical end surface 42 of the clamping end 33 to form a mechanical interlock, which can resist tensile deformation. At the same time, the conical end surface of the clamping end will also produce a certain amount of plastic deformation, so that there is a closed space between the conical end surface and the sealing structure, thereby achieving a sealing effect.

[0057] Optionally, the experimental device also includes a clamp, which includes a sample upper pressing plate 37 and a sample lower pressing plate 34. The middle parts of the sample upper pressing plate 37 and the sample lower pressing plate 34 are both split structures. The sample upper pressing plate 37 abuts against the lower surface of the clamping step 43 at the upper part of the clamping end 33, and the sample lower pressing plate 34 abuts against the upper surface of the clamping step 43 at the lower part of the clamping end 33.

[0058] The sample structure's clamping end features a clamping step to absorb the forces applied during stress corrosion testing. This design primarily transfers the tensile load from the sealing interface (tapered end face) to the fixture press. This design maintains near-zero stress in the sealing area throughout the test, effectively avoiding micro-leakage issues caused by sample deformation in traditional solutions and significantly improving sealing reliability under high-pressure supercritical conditions.

[0059] Optionally, the fixture further comprises: The upper end surface of the sample support stand 26 is located above the clamping step 43 on the upper part of the clamping end 33 and is connected to the sample upper pressing piece 37 through the upper clamp fastening bolt 35; The lower clamp support base 39 is located below the clamping step 43 at the lower portion of the clamping end 33 and is connected to the sample lower pressing plate 34 via the lower clamp fastening bolts 38 .

[0060] It can be understood that the upper and lower sample pressing plates are both split along the centerline (two halves for easy assembly and placement of the sample). The upper pressing plate is fixed to the upper end surface of the sample support frame 26 by fastening bolts, and the lower pressing plate is fixed to the lower fixture support base 39 by fastening bolts. The upper and lower pressing plates secure the sample by pressing the clamping step 43.

[0061] The split-type tabletting fixture decouples the load transfer path from the sealing interface by abutting the clamping step 43, reducing loading and unloading time to 10 minutes. The rigid framework formed by the support frame and base ensures precise alignment of the load axes, eliminating seal failure caused by uneven loading. This structure is beneficial in that it prevents the sealing joint on the inlet and outlet pipes 5 from separating from the seal at the sample's tapered end face 42 due to tensile loads (even slight deformation can affect the sealing effect), which could affect the sealing effect.

[0062] Optionally, the CO2 circulation loop includes a gas booster pump 15, a preheater 12, a cooler 1, and a filter, and is isolated from the internal space of the high-temperature and high-pressure autoclave 27.

[0063] It can be understood that the preheater 12 is used to preheat the CO2 gas so that the gas reaching the high-temperature autoclave 27 is quickly heated to the experimental temperature; the high-temperature autoclave 27 is used to maintain a high-temperature environment. In particular, the inert gas argon is introduced into the autoclave to protect the outer surface of the sample from being oxidized in the high-temperature environment and eliminate the impact of high-temperature air oxidation on the stress corrosion performance of the sample; the cooler 1 is used to cool the gas flowing out of the high-temperature autoclave 27 to reduce corrosion and high-temperature damage to subsequent pipelines.

[0064] Optionally, the stretching shaft 41 of the mechanical loading system is connected to the lower fixture support base 39 through a threaded connection, and the entire system is placed outside the high-temperature autoclave 27 .

[0065] It is understandable that the external isolation of the mechanical loading system allows the stretching shaft 41 to be completely isolated from the corrosive environment, thereby reducing the equipment failure rate and extending the service life.

[0066] In addition, this embodiment also provides a supercritical carbon dioxide flow accelerated corrosion and stress corrosion performance evaluation test method, comprising the following steps: 1. Preparation before the experiment 1.1. Sample assembly and sealing verification Assemble the sample body 29 and the upper and lower sealing joints 40 and perform an airtightness test.

[0067] Install the lower fixture support base 39, place the sample and fix the lower pressing piece.

[0068] Assemble the sample upper structure and fix it to the upper fixture, and adjust the stretching axis 41 through the mechanical loading mechanism 9 to achieve sample pre-tightening.

[0069] 1.2 System Preprocessing Pre-flow carbon dioxide gas to remove other gases in the pipeline.

[0070] The gas booster pump 15 cooperates with the back pressure valve 21 to increase the pressure of carbon dioxide to the test required value and pass it into the hollow cavity 44 of the sample body 29.

[0071] Argon gas is introduced into the high-temperature autoclave 27, and the heating and protection systems are started to raise the temperature to a predetermined operating temperature.

[0072] 2. Test Execution 2.1. Flow Accelerated Corrosion Test (FAC) The flow rate of the gas booster pump 15 is adjusted to control the gas flow rate in the hollow cavity 44 to the test set value.

[0073] Keep the mechanical loading system closed and maintain only the supercritical carbon dioxide environment.

[0074] 2.2. Stress corrosion testing (SCC) The mechanical loading mechanism 9 is turned on to apply stress to the sample at a preset loading rate, or to stretch the sample to a target strain and then maintain the stress.

[0075] A supercritical carbon dioxide environment was simultaneously maintained to monitor the corrosion and stress coupling behaviors of the samples.

[0076] 3. Data Analysis 3.1 Mechanical properties analysis Analyze the changes in the mechanical properties of materials before and after the test (such as yield strength, tensile strength, etc.).

[0077] Specifically, surface morphology characterization can use scanning electron microscopy (SEM) and other means to observe the surface corrosion morphology and crack distribution of the sample; combined with energy spectrum analysis (EDS) and other means, the composition and structural characteristics of the corrosion products can be studied.

[0078] The beneficial effects of the present invention are: (1) It can be used to conduct high-flow accelerated corrosion tests and stress corrosion tests on materials at the same time; (2) Protecting samples from being oxidized by ambient gases in high temperature environments; (3) Avoid corrosion of high-temperature and high-pressure autoclave bodies and reduce equipment maintenance costs.

[0079] The above description and the accompanying drawings sufficiently illustrate the embodiments of the present disclosure to enable those skilled in the art to practice them. Other embodiments may include structural and other changes. The embodiments represent only possible variations. Unless expressly required, individual components and functions are optional, and the order of operations may vary. Portions and features of some embodiments may be included in or replace portions and features of other embodiments. The embodiments of the present disclosure are not limited to the structures described above and shown in the accompanying drawings, and various modifications and changes may be made without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims.

Claims

1. A sample structure for supercritical carbon dioxide corrosion testing, characterized in that: include: The sample body (29) is provided with an axially penetrating hollow cavity (44) therein, wherein the hollow cavity (44) is used to pass a high-pressure flowing carbon dioxide medium; The clamping end (33) is located at both ends of the sample, and its outer surface is provided with a clamping step (43). The end of the clamping end (33) is provided with a tapered end surface (42). The clamping step (43) is used to bear the tensile load, and the tapered end surface (42) is used to connect with the sealing joint for sealing.

2. The sample structure according to claim 1, characterized in that The tapered end surface (42) and the sealing joint form a seal through mechanical extrusion.

3. The sample structure according to claim 1, characterized in that The cone angle of the conical end surface (42) is 15° to 60°.

4. An experimental device for supercritical carbon dioxide corrosion testing, characterized in that: include: The sample structure for supercritical carbon dioxide corrosion testing according to any one of claims 1 to 3; A CO2 circulation loop is connected to the hollow cavity (44) of the sample structure to form an independent closed flow path; a high-temperature autoclave (27) with a built-in inert gas protective layer covering the outer surface of the sample structure; A mechanical loading system is used to connect the fixtures of the sample structure and apply tensile load.

5. The experimental device according to claim 4, characterized in that: Also includes: A sealed joint for connecting the sample structure with the CO2 circulation loop; The inner side surface of the sealing joint is provided with an internal thread for cooperating with the clamping end (33) of the sample structure; and / or, A right-angle step structure is provided inside the sealing joint for cutting into the tapered end surface (42) to achieve sealing.

6. The experimental device according to claim 4, characterized in that Also includes: The clamp comprises a sample upper pressing piece (37) and a sample lower pressing piece (34), wherein the middle parts of the sample upper pressing piece (37) and the sample lower pressing piece (34) are both split-type structures, the sample upper pressing piece (37) abuts against the lower surface of the clamping step (43) at the upper part of the clamping end (33), and the sample lower pressing piece (34) abuts against the upper surface of the clamping step (43) at the lower part of the clamping end (33).

7. The experimental device according to claim 6, characterized in that The fixture further comprises: The upper end surface of the sample support stand (26) is located above the clamping step (43) on the upper part of the clamping end (33) and is connected to the sample upper pressing plate (37) through the upper clamp fastening bolt (35); The lower clamp support base (39) is located below the clamping step (43) at the lower part of the clamping end (33) and is connected to the sample lower pressing plate (34) through the lower clamp fastening bolt (38).

8. The experimental device according to claim 7, characterized in that: The tensile shaft (41) of the mechanical loading system is connected to the lower fixture support base (39) through a threaded connection, and the entire system is placed outside the high-temperature autoclave (27).

9. The experimental device according to claim 4, characterized in that: The inert gas protective layer is formed by argon gas introduced into the high-temperature autoclave (27).

10. The experimental device according to claim 4, characterized in that: The CO2 circulation loop includes a gas booster pump (15), a preheater (12), a cooler (1), and a filter, and is isolated from the internal space of the high-temperature and high-pressure autoclave (27).

Images