System and method for testing permeability of magnesium hydride composite hydrogen storage briquette

Abstract

The invention discloses a system and method for testing the permeability of a magnesium hydride composite hydrogen storage briquette, and the system comprises a testing device which is connected with a vacuum pump and a pressure difference transmitter through a pipeline; the hydrogen conveying device is connected with a flow controller through a pressure reducing valve, and the flow controller is connected with the testing device; when the permeability of the pressing block is tested, hydrogen is conveyed into the testing device through the hydrogen conveying device, the pressure difference between the two ends of the testing device is monitored through the pressure difference transmitter, and the permeability of the pressing block is calculated in combination with the size of the pressing block. The system can accurately control the test environment and ensure the stability of parameters such as hydrogen flow and pressure in the test process; meanwhile, the pressure difference between the two ends of the testing device can be monitored in real time, the permeability of the pressing block can be accurately calculated in combination with the size information of the pressing block, the testing accuracy and reliability are improved, different testing requirements are met, and the technical defect that in the prior art, the axial permeability and the radial permeability of the composite hydrogen storage pressing block cannot be tested respectively is overcome.

Description

Technical Field

[0001] The invention belongs to the technical field of permeability testing of magnesium hydride composite hydrogen storage compacts, and in particular relates to a system and method for testing the permeability of magnesium hydride composite hydrogen storage compacts. Background Art

[0002] Magnesium-based solid-state hydrogen storage technology has the advantages of high hydrogen storage density (7.6wt%), safety, low cost (the raw material is abundant in the earth's crust), and stable circulation. It is one of the important directions for the development of large-scale hydrogen storage technology at this stage. However, due to the limitations of the thermodynamic characteristics of the reaction, the high reaction kinetics of magnesium hydride can only be fully utilized in applications when the heat released or absorbed during the hydrogen absorption or desorption process is fast enough; if the heat is not released or absorbed in time, the magnesium hydride hydrogen absorption or desorption process will stop. Therefore, magnesium hydride hydrogen storage materials must have good heat transfer properties during use in order to continuously and quickly release or absorb hydrogen.

[0003] Magnesium hydride composite hydrogen storage briquette is made by cold pressing magnesium hydride powder and high thermal conductivity materials (expanded graphite, etc.) in a mold. It is an effective device for strengthening bed heat transfer and can evenly distribute magnesium hydride powder in the bed to prevent powder agglomeration from causing hydrogen storage material to absorb hydrogen and expand, resulting in stress concentration on the tank body.

[0004] At present, the permeability testing equipment for magnesium hydride composite hydrogen storage briquettes on the market is unable to separately test the two important permeabilities of the composite hydrogen storage briquettes, axial and radial, during the permeability testing of magnesium hydride composite hydrogen storage briquettes. This results in the inability to fully grasp the mass transfer performance of the briquettes and the inability to effectively carry out hydrogen storage operations. Summary of the invention

[0005] The purpose of the present invention is to provide a magnesium hydride composite hydrogen storage briquette permeability testing system and method to solve the technical defect that the prior art cannot test the two important axial and radial permeabilities of the composite hydrogen storage briquette separately, which makes it impossible to fully grasp the mass transfer performance of the briquette and cannot effectively carry out hydrogen storage operations.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: In a first aspect, a magnesium hydride composite hydrogen storage compact permeability testing system is provided, comprising: A test device, to which a vacuum pump and a differential pressure transmitter are connected through pipelines; A hydrogen delivery device, connected to a flow controller via a pressure reducing valve, wherein the flow controller is connected to the testing device; When the briquette permeability test is performed, hydrogen is delivered to the testing device through the hydrogen delivery device, and the pressure difference at both ends of the testing device is monitored by the differential pressure transmitter, and the briquette permeability is calculated in combination with the briquette size.

[0007] Further, the testing device comprises an upper shell and a lower shell, and the upper shell and the lower shell are connected by bolts; The upper shell is communicated with the lower shell, a sample slot is provided in one end of the upper shell connected with the lower shell, and a pressing block is built in the sample slot.

[0008] Furthermore, one end of the lower shell away from the upper shell is an air inlet end, and one end of the upper shell away from the lower shell is an air outlet end.

[0009] Furthermore, the cross section of the sample slot is rectangular.

[0010] Furthermore, the pressing block is a rectangular structure.

[0011] Furthermore, the length of the pressing block is greater than the length of the test channel formed between the upper shell and the lower shell.

[0012] Furthermore, the upper shell and the lower shell have the same structure.

[0013] Furthermore, the hydrogen delivery device is a hydrogen cylinder.

[0014] Furthermore, the pressing block is a cube.

[0015] In a second aspect, a method for testing the permeability of a magnesium hydride composite hydrogen storage compact is provided, the method being performed using the testing system as described above, comprising: Input replacement gas into the pipeline, and repeatedly evacuate and inflate it to make the hydrogen content in the pipeline reach the preset value; The flow controller is used to set different hydrogen flow rates into the test device, and the differential pressure transmitter is used to obtain the differential pressure at both ends of the test device; Based on the pressure difference, combined with the sample dimensions, the compact permeability was calculated.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. The system can accurately control the test environment by integrating equipment such as vacuum pumps, differential pressure transmitters and flow controllers to ensure the stability of parameters such as hydrogen flow and pressure during the test; at the same time, the differential pressure transmitter can monitor the pressure difference at both ends of the test device in real time, and combined with the size information of the briquette, it can accurately calculate the permeability of the briquette to improve the accuracy and reliability of the test; finally, the hydrogen delivery device is connected to the flow controller through a pressure reducing valve, which can easily adjust the input amount and speed of hydrogen to meet different test requirements, solving the problem that the existing technology cannot test the two important axial and radial permeabilities of the composite hydrogen storage briquette separately during the permeability test of the magnesium hydride composite hydrogen storage briquette, which makes it impossible to fully grasp the mass transfer performance of the briquette and effectively carry out hydrogen storage operations.

[0017] 2. The split test device makes it easier to install, disassemble and replace the pressure block, which not only improves the test efficiency, but also reduces the difficulty of operation and maintenance costs. At the same time, the interconnected upper and lower shells ensure the smooth flow of hydrogen during the test, avoiding test errors caused by structural problems. Secondly, the sample slot ensures that the pressure block can fit tightly in the slot, reducing the possibility of hydrogen leakage, thereby improving the accuracy of the test.

[0018] 3. After hydrogen enters the test device from the air inlet, it is discharged from the air outlet after the penetration of the compression block, making the test process more efficient because hydrogen can quickly flow through the compression block and complete the test. At the same time, it also reduces the residence time of hydrogen in the test device, reducing potential hydrogen leakage and safety hazards.

[0019] 4. The rectangular cross-section helps hydrogen form a more uniform airflow distribution in the sample slot. Compared with circular or other irregular shapes, the rectangular cross-section reduces the accumulation and eddy current of the airflow at the corners and edges, thereby improving the accuracy and reliability of the test.

[0020] 5. Rectangular briquette can make more effective use of space, achieve full contact with hydrogen, and reduce space waste.

[0021] 6. When the length of the pressure block exceeds the test channel, its two ends can form a closer contact with the edges of the upper shell and the lower shell, which helps to reduce the leakage of hydrogen during the test, thereby improving the sealing and accuracy of the test.

[0022] 7. The upper and lower shells with the same structure have higher interchangeability. When repairing, replacing or upgrading the test device, damaged or worn parts can be easily replaced without worrying about compatibility issues. This interchangeability improves the reliability and availability of the test device.

[0023] 8. As a hydrogen delivery device, hydrogen cylinders have the ability to efficiently store and deliver hydrogen. Because the interior of hydrogen cylinders has been specially treated, they can withstand higher hydrogen pressures, thereby achieving effective storage of hydrogen. When needed, hydrogen cylinders can quickly release hydrogen. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0025] Figure 1 A schematic diagram of the structure of a test device in the permeability test system of the magnesium hydride composite hydrogen storage compact provided by the present invention; Figure 2 A schematic diagram of a permeability testing system for magnesium hydride composite hydrogen storage compacts provided by the present invention; Figure 3 A flow chart of a method for testing the permeability of a magnesium hydride composite hydrogen storage compact provided by the present invention; In the figure: 1. upper shell; 2. lower shell; 3. bolts; 4. sample slot; 5. pressure block. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0027] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0029] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0030] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0031] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it 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 it can be indirectly connected 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.

[0032] Magnesium-based solid-state hydrogen storage technology has the advantages of high hydrogen storage density (7.6wt%), safety, low cost (the raw material is abundant in the earth's crust), and stable circulation. It is one of the important directions for the development of large-scale hydrogen storage technology at this stage. However, due to the limitations of the thermodynamic characteristics of the reaction, the high reaction kinetics of magnesium hydride can only be fully utilized in applications when the heat released or absorbed during the hydrogen absorption or desorption process is fast enough; if the heat is not released or absorbed in time, the magnesium hydride hydrogen absorption or desorption process will stop. Therefore, magnesium hydride hydrogen storage materials must have good heat transfer properties during use in order to continuously and quickly release or absorb hydrogen.

[0033] Magnesium hydride composite hydrogen storage briquette is made by cold pressing magnesium hydride powder and high thermal conductivity materials (expanded graphite, etc.) in a mold. It is an effective device for strengthening bed heat transfer and can evenly distribute magnesium hydride powder in the bed to prevent powder agglomeration from causing hydrogen storage material to absorb hydrogen and expand, resulting in stress concentration on the tank body.

[0034] At present, the permeability testing equipment of magnesium hydride composite hydrogen storage briquette on the market cannot test the two important permeabilities of composite hydrogen storage briquette in the axial direction and radial direction respectively during the permeability testing of magnesium hydride composite hydrogen storage briquette, which makes it impossible to fully grasp the mass transfer performance of the briquette and effectively perform hydrogen storage operation. In order to solve the above-mentioned defects of the prior art, the inventor provides a permeability testing system and method for magnesium hydride composite hydrogen storage briquette.

[0035] The present invention is further described in detail below in conjunction with the accompanying drawings: First, as Figure 1 and Figure 2 As shown, an embodiment of the present invention provides a magnesium hydride composite hydrogen storage block permeability test system, including a test device, a pipeline is connected at both ends of the test device, a valve and a differential pressure transmitter are installed on the pipeline, and the two ends of the differential pressure transmitter are connected to the two ends of the test device, one end of the pipeline is connected to a vacuum pump, and the other end is connected to a pressure reducing valve, and the pressure reducing valve is connected to a hydrogen delivery device, and the hydrogen delivery device is preferably a hydrogen bottle, and the hydrogen delivery device is connected to the test device through a flow controller. The hydrogen bottle, as a hydrogen delivery device, has the ability to efficiently store and deliver hydrogen. Because the inside of the hydrogen bottle is specially treated, it can withstand a higher hydrogen pressure, thereby achieving effective storage of hydrogen. When necessary, the hydrogen bottle can quickly release hydrogen. The hydrogen delivery device is connected to the test device through a flow controller, wherein, when the permeability test of the block 5 is performed, hydrogen is delivered to the test device through a gas replacement device, and the pressure difference at both ends of the test device is monitored by a differential pressure transmitter, and the permeability of the block 5 is calculated in combination with the size of the block 5. During the permeability test of the compact 5, the system can accurately control the test environment by integrating a vacuum pump, a differential pressure transmitter and a flow controller, ensuring the stability of parameters such as hydrogen flow and pressure during the test; at the same time, the differential pressure transmitter can monitor the pressure difference at both ends of the test device in real time, and combined with the size information of the compact 5, it can accurately calculate the permeability of the compact 5, thereby improving the accuracy and reliability of the test; finally, the gas replacement device is connected to the flow controller through a pressure reducing valve, and the input amount and speed of hydrogen can be easily adjusted to meet different test requirements, thus solving the problem that the prior art cannot test the two important axial and radial permeabilities of the composite hydrogen storage compact separately during the permeability test of the magnesium hydride composite hydrogen storage compact, which results in the inability to fully grasp the mass transfer performance of the compact and the inability to effectively perform hydrogen storage operations.

[0036] like Figure 1As shown, the test device includes an upper shell 1 and a lower shell 2. The upper shell 1 and the lower shell 2 have the same structure. The upper shell 1 and the lower shell 2 with the same structure have higher interchangeability. When repairing, replacing or upgrading the test device, damaged or worn parts can be easily replaced without worrying about compatibility issues. This interchangeability improves the reliability and availability of the test device. The upper shell 1 and the lower shell 2 are connected by bolts 3. By adopting a split test device, it becomes easier to install, disassemble and replace the pressure block 5 during the penetration test, which not only improves the test efficiency, but also reduces the difficulty of operation and maintenance costs. The upper shell 1 and the lower shell 2 are connected, and a sample slot 4 is provided in one end of the upper shell 1 and the lower shell 2. The cross section of the sample slot 4 is rectangular, and a pressure block 5 is built in the sample slot 4. The upper shell 1 and the lower shell 2 are connected to each other, which ensures the smooth flow of hydrogen during the test and avoids test errors caused by structural problems. The rectangular cross-section of the sample slot 4 helps the hydrogen to form a more uniform airflow distribution in the sample slot 4. Compared with a circular or other irregular shape, the rectangular cross-section reduces the accumulation and eddy current of the airflow at the corners and edges, thereby improving the accuracy and reliability of the test. Figure 1 As shown, the end of the lower shell 2 away from the upper shell 1 is the air inlet end, and the end of the upper shell 1 away from the lower shell 2 is the air outlet end. After hydrogen enters the test device from the air inlet end, it is discharged from the air outlet end after the penetration of the pressing block 5, making the test process more efficient, because hydrogen can quickly flow through the pressing block and complete the test. At the same time, it also reduces the residence time of hydrogen in the test device, reducing potential hydrogen leakage and safety hazards. The pressing block 5 is a rectangular structure, specifically a cube structure. The rectangular pressing block 5 can more effectively utilize space, achieve full contact with hydrogen, and reduce space waste.

[0037] like Figure 1 As shown, the length of the pressing block 5 is greater than the length of the test channel formed between the upper shell 1 and the lower shell 2. When the length of the pressing block 5 exceeds the test channel, its two ends can form a closer contact with the edges of the upper shell 1 and the lower shell 2, which helps to reduce the leakage of hydrogen during the test, thereby improving the sealing and accuracy of the test. In addition, since the two ends of the pressing block 5 exceed the test channel, it is easier to observe the changes of the pressing block 5 during the test. At the same time, due to the close contact between the pressing block 5 and the upper shell 1, it is easier to record and compare the test data, providing strong support for subsequent research and improvement.

[0038] In a second aspect, this embodiment provides a method for testing the permeability of a magnesium hydride composite hydrogen storage compact, the method being performed using the testing system described above. Figure 3 As shown, including: S101, inputting replacement gas into the pipeline, and repeatedly evacuating and inflating, so that the hydrogen content in the pipeline reaches a preset value; illustratively, Figure 2 As shown, the gas inside the pipeline is replaced first. Before replacing the gas inside the system, the air inside the system pipeline is emptied, and an inert gas such as helium, nitrogen or argon is transported into the system pipeline as an intermediate replacement gas to perform a gas replacement operation; secondly, the content of the original gas inside the system pipeline is reduced by a vacuum pump to improve the gas replacement efficiency; then, as shown Figure 2 As shown, close the V12 valve, open the remaining V1, V2, V3, V4, V5, V6, V7, V8, V9, V10 and V11 stop valves of the system, and then use a vacuum pump to reduce the pressure inside the system pipeline to 0.1pa; then close the V11 stop valve, open the pressure reducing valve 1 to fill the system pipeline with inert gas, and adjust the inflation pressure to 2Mpa. After the inflation is completed, close the pressure reducing valve 1, and then repeat the vacuum and inflation operations to reduce the air volume fraction to 0.05%, and finally make the hydrogen content in the pipeline reach the preset value, which is 95.5% of the hydrogen content in the pipeline.

[0039] S102, setting different hydrogen flow rates into the test device through a flow controller, and obtaining the pressure difference between the two ends of the test device using a differential pressure transmitter; illustratively, Figure 2 As shown, open the V2, V9, V10 and V12 valves, and the gas replacement device adjusts the pressure. Specifically, the gas replacement device is a hydrogen cylinder, and the pressure reducing valve 2 is used to adjust the pressure to 0.1~2MPa. Different hydrogen flow rates are set through the flow controller, and the pressure difference transmitter p4 is monitored to obtain the pressure difference at both ends of the test device; in this solution, valve V12 is a back pressure valve, which can test the permeability of the briquette under different pressures.

[0040] S103, based on the pressure difference, combined with the sample size, calculate the permeability of the compact; illustratively, based on the pressure difference at both ends of the test device obtained in the above step, combined with the size of the compact 5, calculate the permeability of the compact 5. Since the hydrogen pressure gradient of the magnesium hydride bed is not obvious, the flow belongs to the laminar flow section, which is applicable to Darcy's law. Therefore, the permeability can be obtained by the following formula: .

[0041]

[0042] In the formula, is the permeability, m 2 ; q is the volume flow rate, m 3 / s; μ is the dynamic viscosity coefficient, Pa∙s; is the side length of the cubic briquette sample, m; It is the differential pressure Pa measured by the differential pressure transmitter.

[0043] By testing the permeability of magnesium hydride composite hydrogen storage compacts through the permeability testing method, not only can the test environment be accurately controlled to ensure the stability of parameters such as hydrogen flow and pressure during the test, but the pressure difference at both ends of the test device can be monitored in real time through the differential pressure transmitter, and combined with the size information of the compact, the permeability of the compact can be accurately calculated to improve the accuracy and reliability of the test; finally, the hydrogen delivery device is connected to the flow controller through a pressure reducing valve, and the input amount and speed of hydrogen can be easily adjusted to meet different test requirements, which solves the problem that the prior art cannot test the two important axial and radial permeabilities of the composite hydrogen storage compacts separately during the permeability test of magnesium hydride composite hydrogen storage compacts, which makes it impossible to fully grasp the mass transfer performance of the compact and effectively perform hydrogen storage operations.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit its protection scope. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that after reading the present invention, those skilled in the art can still make various changes, modifications or equivalent substitutions to the specific implementation methods of the invention, but these changes, modifications or equivalent substitutions are all within the protection scope of the pending claims of the invention.

Claims

1. A magnesium hydride composite hydrogen storage block permeability test system, characterized in that: include: A test device, to which a vacuum pump and a differential pressure transmitter are connected through pipelines; A hydrogen delivery device, connected to a flow controller via a pressure reducing valve, wherein the flow controller is connected to the testing device; When the briquette permeability test is performed, hydrogen is delivered to the testing device through the hydrogen delivery device, and the pressure difference at both ends of the testing device is monitored by the differential pressure transmitter, and the briquette permeability is calculated in combination with the briquette size.

2. The magnesium hydride composite hydrogen storage block permeability testing system according to claim 1, characterized in that: The testing device comprises an upper shell (1) and a lower shell (2), wherein the upper shell (1) and the lower shell (2) are connected via bolts (3); The upper shell (1) and the lower shell (2) are in communication with each other, and a sample groove (4) is provided in one end of the upper shell (1) connected to the lower shell (2), wherein a pressing block (5) is built in the sample groove (4).

3. The magnesium hydride composite hydrogen storage block permeability testing system according to claim 2, characterized in that: The end of the lower shell (2) away from the upper shell (1) is an air inlet end, and the end of the upper shell (1) away from the lower shell (2) is an air outlet end.

4. The magnesium hydride composite hydrogen storage block permeability testing system according to claim 2, characterized in that: The cross section of the sample tank (4) is rectangular.

5. The magnesium hydride composite hydrogen storage compact permeability testing system according to claim 2, characterized in that: The pressing block (5) is a rectangular structure.

6. The magnesium hydride composite hydrogen storage block permeability testing system according to claim 2, characterized in that: The length of the pressing block (5) is greater than the length of the test channel formed between the upper shell (1) and the lower shell (2).

7. The magnesium hydride composite hydrogen storage compact permeability testing system according to claim 2, characterized in that: The upper shell (1) and the lower shell (2) have the same structure.

8. The magnesium hydride composite hydrogen storage block permeability testing system according to claim 1, characterized in that: The hydrogen delivery device is a hydrogen cylinder.

9. The magnesium hydride composite hydrogen storage compact permeability testing system according to claim 1, characterized in that: The valve V12 is a back pressure valve, which can test the permeability of the compact under different pressures.

10. A method for testing the permeability of magnesium hydride composite hydrogen storage compacts, characterized in that: The method is performed using the test system according to any one of claims 1 to 9, comprising: Input replacement gas into the pipeline, and repeatedly evacuate and inflate it to make the hydrogen content in the pipeline reach the preset value; The flow controller is used to set different hydrogen flow rates into the test device, and the differential pressure transmitter is used to obtain the differential pressure at both ends of the test device; Based on the pressure difference, combined with the sample dimensions, the compact permeability was calculated.

Images