Test structure for hydrogen permeation test under high pressure gas phase hydrogen environment, and installation method and application thereof

Abstract

The application relates to the technical field of hydrogen energy transportation and material performance testing, and relates to a test structure for hydrogen permeation testing under a high-pressure gaseous hydrogen environment, a mounting method and application thereof. The test structure comprises a sample body and an insulating sealing assembly, and the sample body is in a double-stage disc structure. The uppermost edge of the first sealing insulating assembly is flush with the upper end surface of the cylindrical platform, and the sample body is matched with the inner side of the first sealing insulating assembly for installation. The second sealing insulating assembly is in an open-upward shape, and the first sealing insulating assembly is matched with the second sealing insulating assembly for installation. The test surface of the sample body of the test structure is kept consistent with the flow field of the gas main stream, and when the test structure is used for testing, the permeation behavior of the hydrogen flow to the material surface can be truly reflected. All clamping and conducting structures are arranged on the outer part of the pipe wall of the test pipeline or the left part of the sample body, so that flow field disturbance is avoided in the main path of the gas flow.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hydrogen energy transportation and material performance testing, and is a test structure for hydrogen permeation testing under a high-pressure gaseous hydrogen environment, and an installation method and application thereof. BACKGROUND

[0002] In the development of hydrogen energy, efficient and safe transportation of hydrogen has become a technical problem. The hydrogen permeation characteristics in metal pipelines directly affect their service safety, especially under high-pressure gaseous flow conditions, hydrogen-induced failure is prone to occur. Therefore, it is of great significance to construct a structure that can truly simulate a high-pressure gaseous hydrogen environment and realize hydrogen permeation testing of in-service steel materials, for in-depth understanding of hydrogen embrittlement mechanism and evaluation of material service capability.

[0003] Patent application document with publication number CN118688069A discloses a permeation rate testing device and testing method for non-metal pipeline for pure hydrogen transportation, which sets a sealed cavity outside the to-be-detected section of the non-metal pipeline to collect hydrogen permeated therefrom, detects the hydrogen concentration in the sealed cavity through a gas chromatograph, and calculates the permeation condition of the to-be-detected section based on time. Each to-be-detected section can be detected in a certain order; or a sealed cavity can be set outside each to-be-detected section for simultaneous detection.

[0004] Patent application document with publication number CN115814702A discloses a propeller type hydrogen permeation single-view window high-pressure kettle, which includes a kettle body with a single-view window; a sample clamp with a hollow structure installed in the single-view window, one end of which is used to clamp a sample and passes through the single-view window to extend into the interior of the kettle body, and the other end is connected to a hydrogen permeation testing device; an agitation assembly including a propeller extending into the interior of the kettle body and a drive thereof; the hydrogen in the high-pressure kettle is disturbed by the propeller to simulate the flow of hydrogen in the pipeline, and thus the hydrogen permeation degree of the material under the motion state of hydrogen can be tested.

[0005] Currently, the samples commonly used for hydrogen permeation testing are mostly circular sheet structures, which need to be installed by pressing and sealing through clamps on both sides (for example, the appendix of patent application document with publication number CN115814702A, subject name “a propeller type hydrogen permeation single-view window high-pressure kettle”). Figure 5The sample fixture is shown). In the detection of hydrogen permeation performance in a dynamic gas phase environment, in order to achieve airtightness and electrical phase resistance, heavy clamps or special mounting components are often arranged at the upper and lower ends of the sample. However, these clamp structures inevitably form geometric mutations and flow field disturbance areas on the surface of the sample, seriously affecting the uniformity of the high-pressure gas-phase hydrogen flow on the surface of the sample and the stability of the boundary layer, and further deviating the hydrogenation conditions of the sample. Especially in the high-pressure dynamic flow field simulating the actual operation conditions of the pipeline, it is difficult for such structure to truly restore the hydrogen flow scouring and concentration gradient distribution on the surface of the material, which limits the accuracy of the characterization of the hydrogen permeation behavior, and deviates from the engineering practice. Therefore, there is an urgent need for a new sample structure that can be conveniently loaded and unloaded with the test container and can minimize boundary disturbance, in order to improve the authenticity and repeatability of dynamic gas-phase hydrogen permeation testing. SUMMARY

[0006] The present application provides a test structure for hydrogen permeation testing in a high-pressure gas-phase hydrogen environment, as well as its installation method and application, which overcomes the shortcomings of the prior art. The test structure can be repeatedly loaded and unloaded with the test container, and can minimize boundary disturbance.

[0007] One of the technical solutions of the present application is achieved by the following measures: a test structure for hydrogen permeation testing in a high-pressure gas-phase hydrogen environment, comprising a sample body and an insulating sealing assembly, the sample body is a double-stage disc structure, the sample body comprises a cylindrical platform and an annular extension located below the cylindrical platform, the upper end of the extension is integrated with the lower end of the cylindrical platform; the insulating sealing assembly comprises a first sealing insulating assembly and a second sealing insulating assembly, the first sealing insulating assembly is a double-stage ring structure, the uppermost edge of the first sealing insulating assembly is flush with the upper end surface of the cylindrical platform, the sample body is installed in the inner side of the first sealing insulating assembly, the second sealing insulating assembly is a U-shaped structure with an opening facing upward, and the first sealing insulating assembly is installed in the second sealing insulating assembly.

[0008] The following is a further optimization or / and improvement of the above-mentioned one of the technical solutions:

[0009] The extension of the above-mentioned sample body is installed in the second-stage step of the lower part of the first sealing insulating assembly, the second-stage step of the first sealing insulating assembly is installed in the second sealing insulating assembly, and the bottom end surface of the extension is in contact with the upper end surface of the second sealing insulating assembly.

[0010] The uppermost edge of the above-mentioned second sealing insulating assembly is flush with the uppermost end surface of the second-stage step of the first sealing insulating assembly.

[0011] The above-mentioned test structure further comprises a sample side pressing flange for connecting with the fixed flange of the test pipeline, and the outer surface of the second sealing insulating assembly is in contact with the inner wall surface of the sample side pressing flange.

[0012] The test structure further comprises a transition pipe, an upper end of the transition pipe is provided with a connecting part, the connecting part extends into a sample cavity of the cylindrical platform from the middle of the sample side compression flange through the second sealing and insulating assembly, at least one sealing element is arranged between the outer side of the transition pipe and the inner side of the sample side compression flange, auxiliary electrode holes, reference electrode holes and liquid discharge holes are arranged on the pipe wall of the transition pipe, and the inner cavity of the transition pipe is an electrolytic cell.

[0013] The test structure further comprises a test pipe, mounting holes are arranged on the test pipe in a radial direction, the mounting holes are in a stepped shape, the outer edge of the first step of the first sealing and insulating assembly is attached to the first step of the mounting hole, the uppermost edge of the first sealing and insulating assembly and the uppermost end surface of the cylindrical platform are flush with the inner wall of the test pipe, the upper side edge of the second sealing and insulating assembly and the upper end surface of the second step of the first sealing and insulating assembly are attached to the second step of the mounting hole, a fixed flange corresponding to the mounting hole is fixed to the test pipe, the fixed flange is fixedly connected with the sample side compression flange, and the inner wall of the fixed flange is attached to the outer wall of the second sealing and insulating assembly.

[0014] The third technical scheme of the present application is realized by the following measures: the application of the test structure in the hydrogen permeation test under the high-pressure gas-phase hydrogen environment.

[0015] Firstly, the first sealing and insulating assembly is embedded into the mounting hole of the test pipe;

[0016] Then, the sample body is completely embedded into the first sealing and insulating assembly, and the upper end surface of the cylindrical platform of the sample body is flush with the inner surface of the inner wall of the test pipe;

[0017] Subsequently, the second sealing and insulating assembly is installed below the first sealing and insulating assembly, the second step of the first sealing and insulating assembly is enclosed in the second sealing and insulating assembly, and the bottom surface of the extension part of the sample body is attached to the bottom surface in the second sealing and insulating assembly;

[0018] Then, the transition pipe is inserted into the sample side compression flange, extends into the sample cavity of the cylindrical platform of the sample body after passing through the second sealing and insulating assembly;

[0019] Finally, the fixed flange of the test pipe is aligned and installed with the sample side compression flange, and the sample body is firmly clamped.

[0020] The third technical scheme of the present application is realized by the following measures: the application of the test structure in the hydrogen permeation test under the high-pressure gas-phase hydrogen environment.

[0021] The following is a further optimization or / and improvement of the third technical scheme of the present application:

[0022] The method of the application comprises:

[0023] The sample cavity serves as a working electrode, the auxiliary electrode and the reference electrode are inserted into the electrolytic cell of the transition tube, the auxiliary electrode and the reference electrode form a stable electrochemical loop interface with the sample cavity, the auxiliary electrode and the reference electrode are connected to the potentiostat through the quick connection cable, and the continuous test of hydrogen permeation current is carried out.

[0024] The present application has the following beneficial effects:

[0025] (1) The sample body of the tested structure is flatly embedded, the test surface (i.e. the rightmost surface of the cylindrical platform of the sample body) is consistent with the flow field of the main gas flow, and when the test structure is used for testing, the hydrogen flow to the material surface can be truly reflected;

[0026] (2) All clamping and conducting structures (i.e. flange structure and transition tube) are arranged on the outer wall of the test pipeline or the left part of the sample body, compared with the traditional clamping sample piece which introduces flow field disturbance in the main path of gas flow, the present application can avoid introducing flow field disturbance in the main path of gas flow;

[0027] (3) The flange and sealing structure have strong universality and are suitable for various sample materials and test systems;

[0028] (4) The installation process is simple and convenient, supports high repeatability assembly and multi-specification quick replacement, and is a basic process unit of high-pressure dynamic hydrogen permeation test. BRIEF DESCRIPTION OF DRAWINGS

[0029] FIG. 1 shows a front view of the sample body of the present application installed in the test pipeline. Figure 1

[0030] FIG. 4 shows a B-B cross-sectional view of FIG. 3. Figure 2 Figure 1 FIG. 5 shows an axonometric view of FIG. 3.

[0031] FIG. 6 shows a streamline diagram of hydrogen permeation simulation test using a sample clamp to clamp a thin sheet structure sample (inlet flow rate 10 m / s). Figure 3 Figure 1 FIG. 7 shows a streamline diagram of hydrogen permeation simulation test using the test structure of the present application (inlet flow rate 10 m / s).

[0032] FIG. 8 shows a streamline diagram of hydrogen permeation simulation test using a sample clamp to clamp a thin sheet structure sample (inlet flow rate 5 m / s). Figure 4 FIG. 9 shows a streamline diagram of hydrogen permeation simulation test using the test structure of the present application (inlet flow rate 5 m / s).

[0033] Figure 5 FIG. 10 shows a streamline diagram of hydrogen permeation simulation test using a sample clamp to clamp a thin sheet structure sample (inlet flow rate 2 m / s).

[0034] FIG. 11 shows a streamline diagram of hydrogen permeation simulation test using the test structure of the present application (inlet flow rate 2 m / s). Figure 6 FIG. 12 shows a streamline diagram of hydrogen permeation simulation test using a sample clamp to clamp a thin sheet structure sample (inlet flow rate 1 m / s).

[0035] Figure 7 ​​​​​A streamline diagram (inlet flow velocity 5 m / s) of hydrogen permeation simulation test using the test structure described in this invention is shown.

[0036] The codes in the attached diagram are as follows: 1 for mounting hole, 2 for cylindrical platform, 3 for extension, 4 for first sealing and insulating assembly, 5 for second sealing and insulating assembly, 6 for fixing flange, 7 for sample-side clamping flange, 8 for transition pipe, 9 for connection, 10 for sample cavity, 11 for auxiliary electrode hole, 12 for reference electrode hole, 13 for drain hole, 14 for test pipe, a for first-stage step, and b for second-stage step. Figure 2 In the image, the arrow indicates the direction of hydrogen flow. Detailed Implementation

[0037] The present invention is not limited to the following embodiments, and the specific implementation can be determined according to the technical solution of the present invention and the actual situation.

[0038] In this invention, it should be noted that the terms "first," "second," etc., are used only for the convenience of describing the invention and simplifying the description, and are not intended to indicate or imply that the modules or elements referred to must have a specific order and operation, and therefore should not be construed as limitations on the invention, such as the first sealing and insulating assembly.

[0039] For ease of description, the relative positions of the components are described based on the appendix to the instruction manual. Figure 2 The layout is described using a diagrammatic method, such as the positional relationships of front, back, top, bottom, left, and right, which are based on the instructions attached. Figure 2 The orientation of the layout is determined by the direction of the map.

[0040] The present invention will be further described below with reference to embodiments:

[0041] Example 1: As Figures 1 to 3 As shown, a test structure for hydrogen permeation testing under high-pressure gaseous hydrogen environment includes a sample body and an insulating sealing assembly. The sample body has a double-stage disk structure and includes a cylindrical platform 2 and an annular extension 3 located below the cylindrical platform 2. The upper end of the extension 3 is integrated with the lower end of the cylindrical platform 2. The insulating sealing assembly includes a first sealing insulating assembly 4 and a second sealing insulating assembly 5. The first sealing insulating assembly 4 has a double-stage annular structure, and the uppermost edge of the first sealing insulating assembly 4 is flush with the upper end face of the cylindrical platform 2. The sample body is fitted inside the first sealing insulating assembly 4. The second sealing insulating assembly 5 has an upward-opening U-shape, and the first sealing insulating assembly 4 is fitted inside the second sealing insulating assembly 5.

[0042] The sample body supports a variety of material choices: including low alloy steel, stainless steel, nickel-based alloys and other metallic materials of different strength levels, as well as non-metallic materials such as ceramics and polymer composites.

[0043] A physical vapor deposition (PVD), electroplating or spraying other existing hydrogen inhibition coating can also be constructed on the surface of the sample body (i.e. the upper end surface of the cylindrical platform 2) for the study of the interface behavior under various hydrogen permeation environments.

[0044] To enhance versatility, the outer diameter and step height of the sample body support standardized series design (such as φ35 mm, φ30 mm, etc.), which is matched with the flange structure stroke and pipeline size for quick replacement.

[0045] Example 2: As shown in Figure 1 As an optimization of the above examples, the extension 3 of the sample body is fitted into the second step b of the lower part of the first sealing and insulating assembly 4, the second step b of the first sealing and insulating assembly 4 is fitted into the second sealing and insulating assembly 5, and the bottom end surface of the extension 3 is in close contact with the upper end surface of the second sealing and insulating assembly 5.

[0046] The first step a and the second step b are counted from top to bottom.

[0047] The first sealing and insulating assembly 4 is a double-step annular structure formed in one piece, and the outer side surface of the upper step (i.e. the first step a) and the upper end surface of the second step b are in close contact with the mounting hole 1 of the test pipeline 14 wall, forming external insulation and sealing; the inner side is in close contact with the outer wall of the sample body for positioning and isolating the gas from the flange area, achieving primary axial sealing and electrical insulation.

[0048] Example 3: As shown in Figure 1 As an optimization of the above examples, the uppermost edge of the second sealing and insulating assembly 5 is flush with the uppermost end surface of the second step b of the first sealing and insulating assembly 4.

[0049] The bottom end surface of the extension 3 is in close contact with the bottom surface inside the second sealing and insulating assembly 5, and the outer wall of the lower part of the second sealing and insulating assembly 5 is in close contact with the inner wall surface of the fixed flange 6; the inner side surface of the second sealing and insulating assembly 5 is in close contact with the outer wall of the second step b of the first sealing and insulating assembly 4, and the outer side surface of the upper part of the second sealing and insulating assembly 5 is in close contact with the inner surface of the second step b of the mounting hole 1, forming a complete multi-surface contact sealing and electrical insulation structure.

[0050] Example 4: As shown in Figure 1 As an optimization of the above examples, the test structure further includes a sample side compression flange 7 for connecting with the fixed flange 6 of the test pipeline 14, and the bottom surface of the second sealing and insulating assembly 5 is in close contact with the upper end surface of the sample side compression flange 7.

[0051] The flange structure and the sealing and insulation assembly can also be standardized and customized according to different system requirements. The flange connection mode can be designed according to GB / T, ASME standards or special working conditions, and the sealing and insulation assembly can be supported by rubber rings, metal sealing rings, composite sealing gaskets and the like to meet the requirements of high temperature, high pressure, corrosion or dynamic flow hydrogen environment.

[0052] As shown in the above embodiment, the test structure further comprises a transition pipe 8, an upper end of the transition pipe 8 is provided with a connecting part 9, the connecting part 9 extends into a sample concave cavity 10 of the cylindrical platform 2 from the middle of the sample side compression flange 7 after passing through the second sealing and insulation assembly 5, at least one sealing element is arranged between the outer side of the transition pipe 8 and the inner side of the sample side compression flange 7, auxiliary electrode holes 11, reference electrode holes 12 and liquid discharge holes 13 are arranged on the wall of the transition pipe 8, and the inner cavity of the transition pipe 8 is an electrolytic cell. Figure 1

[0053] The auxiliary electrode holes 11 and the reference electrode holes 12 support various structures, including central through type and eccentric blind hole type, and the connection mode can be thread locking, welding or quick plug-in type to adapt to various types of electrochemical instruments.

[0054] After the experiment is completed, the electrolyte is discharged through the liquid discharge hole 13. The liquid discharge hole 13 can be plugged with a plug structure during the experiment.

[0055] The transition pipe 8 is an elongated cylindrical metal pipe or a high-strength insulation material pipe.

[0056] As shown in the above embodiment, the test structure further comprises a test pipe 14, a mounting hole 1 is arranged radially on the test pipe 14, the mounting hole 1 is in a stepped shape, the outer edge of the first step a of the first sealing and insulation assembly 4 is attached to the first step a of the mounting hole 1, the uppermost edge of the first sealing and insulation assembly 4 and the uppermost end surface of the cylindrical platform 2 are flush with the inner wall of the test pipe 14, the upper side edge of the second sealing and insulation assembly 5 and the upper end surface of the second step b of the first sealing and insulation assembly 4 are attached to the second step b of the mounting hole 1, the test pipe 14 corresponding to the mounting hole 1 is fixed with a fixed flange 6, the fixed flange 6 is fixedly connected with the sample side compression flange 7, and the inner wall of the fixed flange 6 is attached to the outer wall of the second sealing and insulation assembly 5. Figures 1 to 3 The upper end surface of the cylindrical platform 2 of the sample body is flush with the inner surface of the inner wall of the test pipe 14, so that the upper end surface of the cylindrical platform 2 of the sample body and the inner wall of the pipe form a smooth and continuous structure, without causing flow field mutation.

[0057] The stepped mounting hole 1 can form a fitting structure with the sample body and the first sealing and insulation assembly 4, thereby improving the structural stability and sealing performance of the sample body and the test pipe 14.

[0058] The stepped mounting hole 1 can form a fitting structure with the sample body and the first sealing and insulation assembly 4, thereby improving the structural stability and sealing performance of the sample body and the test pipe 14.​

[0059] Embodiment 7: As shown in the figure, a method for installing a test structure for hydrogen permeation testing under high-pressure gaseous hydrogen environment, comprising: Figure 1

[0060] First, embed the first sealing and insulating assembly 4 into the mounting hole 1 of the test pipe 14;

[0061] Next, embed the sample body completely into the first sealing and insulating assembly 4, with the upper end surface of the cylindrical platform 2 of the sample body flush with the inner surface of the inner wall of the test pipe 14; to form a continuous airflow wall structure, avoid flow field interference, establish stable wall flow, and form a true boundary layer structure;

[0062] Subsequently, install the second sealing and insulating assembly 5 below the first sealing and insulating assembly 4, with the second level step b of the first sealing and insulating assembly 4 enclosed in the second sealing and insulating assembly 5, and the bottom surface of the extension 3 of the sample body fitted with the bottom surface in the second sealing and insulating assembly 5;

[0063] Next, insert the transition pipe 8 into the sample side compression flange 7, pass through the second sealing and insulating assembly 5, and extend into the sample cavity 10 of the cylindrical platform 2 of the sample body, with the outer wall of the transition pipe 8 forming an interference fit with the through hole of the sample side compression flange 7;

[0064] Finally, align and install the fixed flange 6 of the test pipe 14 with the sample side compression flange 7, and firmly clamp the sample body.

[0065] Pre-drill mounting grooves on the outside of the transition pipe 8 or the inside of the sample side compression flange 7, and install the sealing element in the mounting grooves.

[0066] Embodiment 8: Application of the test structure described in the above embodiments in hydrogen permeation testing under high-pressure gaseous hydrogen environment.

[0067] Embodiment 9: As an optimization of Embodiment 8, the method of application comprises:

[0068] The sample cavity 10 serves as the working electrode, the auxiliary electrode and the reference electrode are inserted into the electrolytic cell of the transition pipe 8, the auxiliary electrode and the reference electrode form a stable electrochemical loop interface with the sample cavity 10, and the auxiliary electrode and the reference electrode are connected to the potentiostat through the quick-connection cable for continuous testing of hydrogen permeation current.

[0069] Embodiment 10: Processing and assembly of metal material sample body

[0070] ​The embodiment selects a 316L stainless steel disc with a thickness of 4 mm as the original blank of the sample body, the initial outer diameter is 35 mm, and the surface roughness is Ra≤0.8 μm after mechanical finishing. Then, the double-stage disc structure is processed by numerical control CNC equipment: the upper stage (i.e. the cylindrical platform 2) is provided as a boss with a diameter of 20 mm and a height of 2.8 mm, the platform thickness is 0.8 mm, and is used as a gas flow field contact surface; the lower stage (the extension part 3) is processed as a ring-shaped platform structure with a diameter of 35 mm and a thickness of 1.2 mm, which is used as a positioning and sealing compression area. At the same time, a circular shallow cavity (i.e. the sample cavity 10) is dug in the center of the sample body, the cavity depth is 3.2 mm, the diameter is 10 mm, and is used as a working electrode, the right side bottom surface of the circular shallow cavity is a hydrogen permeation reaction surface, and the inner wall is a current collection channel.

[0071] A stepped mounting hole 1 is provided on the wall surface of the test pipe 14, which is used for mounting the sample body and the matching sealing assembly (including the first sealing and insulating assembly 4 and the second sealing and insulating assembly 5): the upper port of the mounting hole 1 (i.e. the first stage a) has a diameter of 22 mm and a depth of 0.8 mm, which is flush with the uppermost edge of the upper stage of the sample body and the first sealing and insulating assembly 4; the diameter of the second stage b of the mounting hole 1 is 39 mm, which is in close contact with the outer edge of the second sealing and insulating assembly 5.

[0072] The sample body assembly process is as follows:

[0073] Firstly, the first sealing and insulating assembly 4 is embedded in the mounting hole 1 of the test pipe 14, the first sealing and insulating assembly 4 is made of PPS engineering plastic by injection molding, the thickness is 2 mm, and has a double-stage ring structure, the outer diameter of the upper stage (i.e. the first stage a) is 22 mm, the outer edge of the upper stage is in close contact with the upper port of the mounting hole 1, and the height is 0.8 mm; the outer diameter of the lower stage (i.e. the second stage b) is 37 mm, and the height is 3.2 mm, the outer side and bottom surface of the lower stage of the first sealing and insulating assembly 4 are in close contact with the inner surface of the second sealing and insulating assembly 5. The first sealing and insulating assembly 4 simultaneously bears the functions of sample body outer circle positioning, gas isolation and primary electrical insulation.

[0074] Then, the processed 316L sample body is completely embedded in the first sealing and insulating assembly 4, ensuring that the uppermost end surface is flush with the inner wall surface of the test pipe 14, forming a continuous gas flow wall structure, avoiding flow field interference.

[0075] Subsequently, the second sealing and insulating assembly 5 is installed below the first sealing and insulating assembly 4, the second sealing and insulating assembly 5 is made of PEEK material, the thickness is 2 mm, and is a hollow cylindrical structure with a through hole, the bottom surface of the extension part 3 of the sample body is in close contact with the bottom surface in the second sealing and insulating assembly 5, a diameter of 10 mm through hole is provided in the center of the second sealing and insulating assembly 5 for the insertion and connection of the transition pipe 8.

[0076] After the sample body and the sealing assembly are positioned, the sample side compression flange 7 is attached to the outer side of the second sealing and insulating assembly 5. The sample side compression flange 7 is made of stainless steel and has a thickness of 6 mm. The inner hole size is slightly larger than the outer diameter of the transition tube 8, and six symmetric bolt holes are provided around the flange. Then, the fixed flange 6 of the test pipeline 14 is aligned and installed. High-strength stainless steel bolts of M4 specification are sequentially inserted into the bolt holes, and uniform axial compression force is applied in a diagonal order. The tightening torque is 8 N·m. During the flange compression process, the sample body is firmly clamped, the sealing assembly is three-sidedly attached, the transition tube 8 is stably positioned at the end, and the overall assembly is completed.

[0077] After the sample body is compressed, the transition tube 8 is inserted into the through hole of the sample side compression flange 7, passes through the second sealing and insulating assembly 5, and extends into the sample recess 10 of the sample body. The transition tube 8 is made of acrylic material and has an interference fit with the through hole of the sample side compression flange 7. A sealing element (PTFE or PFA sealing gasket) is installed between the outer side of the transition tube 8 and the inner side of the sample side compression flange 7. A tapered surface compression or O-ring design is used to achieve double-point radial sealing through axial pressure, ensuring that hydrogen or electrolyte does not leak.

[0078] Finally, the auxiliary electrode and the reference electrode of the electrolytic cell are inserted into the electrolytic cell through the transition tube 8 to form a stable electrochemical loop interface with the sample recess 10. The outside is connected to a constant potential instrument through a quick connection cable to realize continuous testing of hydrogen permeation current. The system is subjected to a leakage test under 10 MPa nitrogen or helium gas. No gas escape is considered as a qualified seal, and the system can be used for formal high-pressure hydrogen permeation experiments. After the experiment is completed, the electrolyte is discharged through the drain hole 13.

[0079] According to the working principle of the electrochemical three-electrode system, the auxiliary electrode and the reference electrode are placed in the electrolytic cell.

[0080] Example 11: Preparation and assembly of non-metal material sample body

[0081] In this example, the sample body material is replaced with an alumina ceramic disc (Al2O3, purity ≥ 99.5%, thickness 4.0 mm) based on Example 10. Considering the high brittleness and easy edge collapse characteristics of ceramic materials, the sample is processed using a combination of ultrasonic grinding and precision grinding technology to form a stepped structure with an upper step diameter of 20 mm and a thickness of 0.8 mm, and a lower step diameter of 35 mm and a thickness of 1.2 mm. The sample recess 10 is shaped by laser processing with a depth of 3.2 mm.

[0082] The inner wall of the sample cavity 10 is coated with a layer of silver paste conductive layer, which forms a stable conductive interface after drying at 120°C for 1 hour, replacing the electrode passage of the metal body. The remaining sealing assembly, flange, and transition tube 8 are the same as in Example 10, but the tightening torque is controlled to be ≤5 N·m during compression to avoid ceramic cracking. The electrode contacts the sample cavity 10 in a flexible probe or liquid contact mode.

[0083] Example 12: Preparation and application of metal-based coating sample

[0084] Based on Example 10, the sample body is still a 316L stainless steel disc, and the same sample body and sample cavity 10 design is retained. The difference is that the uppermost end surface of the cylindrical platform 2 of the sample body (which contacts hydrogen) is pre-treated (sandblasting + ultrasonic cleaning) and then coated with a TiN coating layer with a thickness of about 500 nm using physical vapor deposition (PVD) technology. The TiN coating layer is used to inhibit the hydrogen permeation rate.

[0085] The sample body installation, sealing assembly, transition tube 8 structure, and operation process are exactly the same as in Example 10. This structure (sample body with TiN coating) is suitable for studying the performance stability and film failure behavior of hydrogen inhibition coatings under high-pressure flowing gas. The inside of the sample cavity 10 is not coated and retains a metal bare area to form an internal and external interface permeation passage.

[0086] The present application provides an embedded stepped hydrogen permeation test sample (sample body) with standardized structure, repeatable installation and removal, and minimized flow field disturbance, as well as its installation assembly (including a sealing assembly, etc.), which can realize real simulation testing of material hydrogen permeation performance under high-pressure gas phase conditions. The sample body is adapted to be installed on the inner wall of the pipeline of a gas circulation system, has excellent airflow adhesion, structural sealing, and electrode conduction connection functions, and effectively ensures testing accuracy and system adaptability.

[0087] Flow field disturbance comparison experiment:

[0088] (1) In actual hydrogen transportation engineering, the hydrogen flow rate in the pipeline can reach more than 10 m / s, which is in a high-speed shear flow state. The sample structure used in traditional hydrogen permeation testing is usually a thin sheet clamped in the middle, which is fixed and insulated by a clamp-shaped structure (such as the clamp-shaped structure in the appendix of the patent with the publication number CN115814702A and the subject name "A propeller type hydrogen permeation single-view window high-pressure kettle"). Figure 5The simulation results show that under the condition of an inlet flow velocity of 10 m / s, the traditional clamping type sheet structure forms stable vortexes at both ends of the sample, the boundary layer is separated, and the hydrogen concentration and flow velocity distribution on the surface of the sample are extremely uneven, which is difficult to truly reflect the dynamic hydrogen permeation behavior under the operation of the pipeline (see Figure 4 ). The sample body of the application is flush with the pipe wall of the test pipeline 14, can significantly reduce local flow disturbance, maintain a stable and uniform surface flow state under the condition of an inlet flow velocity of 10 m / s (see Figure 5 ), and is more conducive to establishing a stable hydrogen concentration gradient.

[0089] (2) In the conventional hydrogen permeation test in the laboratory, the flow velocity of the gas-phase hydrogen is usually maintained at about 5 m / s due to the limitation of the flow control ability of the equipment. Although this flow velocity is lower than the actual operating condition of the engineering pipeline, it can still reflect part of the permeation characteristics of the material in the dynamic gas flow environment. The simulation results show that under this flow velocity condition, the clamping structure of the traditional clamping type sheet structure (such as the publication CN115814702A, the subject name of which is “a propeller type hydrogen permeation single-view window autoclave”) forms a protrusion on both sides of the sample, which causes disturbance in the local flow field, and obvious backflow and vortexes appear, which destroys the continuity of the hydrogen gas boundary layer on the surface of the sample, and further affects the stability of the hydrogen concentration distribution (see Figure 6 ). The sample body of the application is flush with the pipe wall of the test pipeline 14, can significantly reduce local flow disturbance, maintain a stable and uniform surface flow state under the condition of an inlet flow velocity of 5 m / s (see Figure 7 ), and is more conducive to establishing a stable hydrogen concentration gradient.

[0090] Compared under different gas flow velocities, the sample body of the application is flush with the inner wall of the pipeline, and the boundary of the sample area is continuously transitioned without a sudden flow disturbance source. Under the same flow velocity condition, the sample body of the application significantly reduces the formation of backflow and secondary flow near the wall, so that the hydrogen gas maintains a uniform and stable high-shear flow on the surface of the sample body, which is conducive to simulating the hydrogen permeation environment under the actual pipeline service condition. The optimized design of the application ensures the flow consistency of the sample test surface (the uppermost end surface of the cylindrical platform 2 of the sample body) and the repeatability of the experimental results, which is the key structural basis for realizing the high-pressure gas-phase dynamic hydrogen permeation test.

[0091] The above technical features respectively constitute embodiments of the application, have strong adaptability and implementation effect, and can be increased or decreased according to actual needs to meet the needs of different situations.

Claims

1. A test structure for hydrogen permeation testing under high pressure gas phase hydrogen environment, characterized by, The test sample body and the insulating sealing assembly, the test sample body is a double-stage disc structure, the test sample body includes a cylindrical platform and an annular extension located below the cylindrical platform, the upper end of the extension is integrated with the lower end of the cylindrical platform; the insulating sealing assembly includes a first sealing insulating assembly and a second sealing insulating assembly, the first sealing insulating assembly is a double-stage annular structure, the uppermost edge of the first sealing insulating assembly is flush with the upper end surface of the cylindrical platform, the test sample body is fitted and installed inside the first sealing insulating assembly, the second sealing insulating assembly is a U-shaped structure with an opening facing upward, the first sealing insulating assembly is fitted and installed inside the second sealing insulating assembly.

2. The test structure for hydrogen permeation test under high pressure gas phase hydrogen environment according to claim 1, characterized by, The extension of the test sample body is fitted and installed in the second-stage step of the lower part of the first sealing insulating assembly, the second-stage step of the first sealing insulating assembly is fitted and installed inside the second sealing insulating assembly, and the bottom end surface of the extension is attached to the upper end surface of the second sealing insulating assembly.

3. The test structure for hydrogen permeation testing under high pressure gas phase hydrogen environment according to claim 2, characterized in that, The uppermost edge of the second sealing insulating assembly is flush with the uppermost end surface of the second-stage step of the first sealing insulating assembly.

4. The test structure for hydrogen permeation testing under high pressure gas phase hydrogen environment according to claim 2 or 3, characterized in that, It also includes a test sample side pressing flange for connecting with the fixed flange of the test pipeline, and the bottom surface of the second sealing insulating assembly is attached to the upper end surface of the test sample side pressing flange.

5. The test structure for hydrogen permeation testing under high pressure gas phase hydrogen environment according to claim 4, characterized in that, It also includes a transition tube, the upper end of the transition tube is provided with a connecting part, the connecting part extends into the test sample cavity of the cylindrical platform after passing through the second sealing insulating assembly from the middle of the test sample side pressing flange, at least one sealing element is arranged between the outer side of the transition tube and the inner side of the test sample side pressing flange, the tube wall of the transition tube is provided with an auxiliary electrode hole, a reference electrode hole and a liquid discharge hole, and the inner cavity of the transition tube is an electrolytic cell.

6. The test structure for hydrogen permeation testing under high pressure gas phase hydrogen environment according to claim 5, characterized in that, It also includes a test pipeline, the test pipeline is radially provided with a mounting hole, the mounting hole is a stepped structure, the outer edge of the first-stage step of the first sealing insulating assembly is attached to the first-stage step of the mounting hole, the uppermost edge of the first sealing insulating assembly and the uppermost end surface of the cylindrical platform are flush with the inner wall of the test pipeline, the upper side edge of the second sealing insulating assembly and the upper end surface of the second-stage step of the first sealing insulating assembly are attached to the second-stage step of the mounting hole, the fixed flange is fixed to the test pipeline corresponding to the mounting hole, the fixed flange is fixedly connected with the test sample side pressing flange, and the inner wall of the fixed flange is attached to the outer wall of the second sealing insulating assembly.

7. A method of installing the test structure for hydrogen permeation testing under a high-pressure gas-phase hydrogen environment according to claim 5 or 6, characterized by, It includes: First, embed the first sealing insulating assembly into the mounting hole of the test pipeline; Then, completely embed the test sample body into the first sealing insulating assembly, and the upper end surface of the cylindrical platform of the test sample body is flush with the inner surface of the inner wall of the test pipeline; Subsequently, install the second sealing insulating assembly below the first sealing insulating assembly, the second-stage step of the first sealing insulating assembly is enclosed in the second sealing insulating assembly, and the bottom surface of the extension of the test sample body is attached to the bottom surface in the second sealing insulating assembly; Then, insert the transition tube into the test sample side pressing flange, pass through the second sealing insulating assembly, and extend into the test sample cavity of the cylindrical platform of the test sample body; Finally, align and install the fixed flange of the test pipeline with the test sample side pressing flange, and firmly clamp the test sample body.

8. The application of the test structure according to any one of claims 1 to 6 in hydrogen permeation test in a high-pressure gas-phase hydrogen environment.

9. Use according to claim 8, characterized in that, The method of the application includes: The sample cavity is used as a working electrode, and the auxiliary electrode and the reference electrode are inserted into the electrolytic cell of the transition tube. The auxiliary electrode and the reference electrode form a stable electrochemical loop interface with the sample cavity. The auxiliary electrode and the reference electrode are connected to a constant potential instrument through a quick connection cable for continuous testing of hydrogen permeation current.

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