Magnesium hydride hydrogen storage device and method with double-bin structure

Abstract

The invention belongs to the technical field of hydrogen storage devices, and relates to a magnesium hydride hydrogen storage device with a double-bin structure and a method, the magnesium hydride hydrogen storage device comprises a first magnesium hydride bed bin and a second magnesium hydride bed bin connected with the first magnesium hydride bed bin; and the first magnesium hydride bed bin and the second magnesium hydride bed bin are both connected with the ejector. The magnesium hydride hydrogen storage device has efficient heat exchange and high-capacity hydrogen desorption capabilities; compared with a traditional single bed layer structure, the hydrogen storage capacity of the device can be increased by 30%.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogen storage devices, and relates to a magnesium hydride hydrogen storage device and method with a dual-chamber configuration. Background Art

[0002] As a highly potential solid hydrogen storage material, magnesium hydride has received extensive attention in the field of hydrogen energy storage in recent years due to its high hydrogen storage density, good reversibility, and low cost. However, the core challenge in its practical application lies in the thermal management problem: the hydrogen absorption reaction is an exothermic process (ΔH ≈ -75 kJ / mol H 2 ), while the dehydrogenation reaction requires a large amount of heat absorption (ΔH ≈ 75 kJ / mol H 2 ), and the reaction temperature usually needs to be maintained in the high temperature range of 250 - 400°C. Without an effective thermal management design, the energy consumption in the dehydrogenation stage will significantly increase the operating cost, severely restricting its commercial application.

[0003] To address this problem, various thermal management strategies have been proposed in the prior art. Among them, in scenarios with high-temperature steam consumption or production capabilities (such as industrial boilers, power plants, or large-scale high-temperature thermal energy storage systems), the thermal management design of magnesium hydride hydrogen storage devices is particularly crucial. The reaction heat released during the hydrogen absorption stage can be recovered by heat transfer media (such as molten salts, heat transfer oils, etc.) and used to produce high-quality steam, thereby partially offsetting the energy consumption requirements in the dehydrogenation stage. For example, Patent CN117899771A proposes a thermal management device for a magnesium hydride reactor using molten salt as a heat transfer medium, precisely regulating the temperature and flow rate of the molten salt through a temperature control unit and a flow meter, and achieving efficient recovery and utilization of waste heat in combination with a heat exchange section and a heat storage device. Similarly, Patent CN117404949A uses phase change materials (PCM) combined with a circulating water system for thermal management, and adjusts the temperature of the phase change materials through cold / hot water under abnormal conditions to maintain the stable operation state of the hydrogen storage bed layer.

[0004] However, there are still significant technical bottlenecks in traditional thermal management solutions. To improve the heat transfer efficiency, the magnesium hydride bed layer usually adopts a compact heat transfer structure design, but this also leads to uneven temperature distribution inside the bed layer. Especially on the outlet side of the heat transfer fluid, due to insufficient heat transfer, some magnesium hydride is difficult to reach the temperature required for dehydrogenation, resulting in incomplete reactions and a serious loss of hydrogen storage capacity (up to 20 - 30%).

[0005] Therefore, there is an urgent need to develop a new type of magnesium hydride hydrogen storage device that can optimize the temperature distribution of the magnesium hydride bed layer, reduce capacity loss, and improve the overall hydrogen storage and release efficiency while ensuring efficient heat transfer. Summary of the Invention

[0006] The object of the present invention is to solve the problems in the prior art, and to provide a magnesium hydride hydrogen storage device and method with a double-chamber configuration, which can achieve high-efficiency heat exchange and high-capacity hydrogen release ability at the same time.

[0007] To achieve the above object, the present invention adopts the following technical solutions: In the first aspect, the present invention provides a magnesium hydride hydrogen storage device with a double-chamber configuration, including a first magnesium hydride bed chamber and a second magnesium hydride bed chamber connected thereto; both the first magnesium hydride bed chamber and the second magnesium hydride bed chamber are connected to an ejector.

[0008] Preferably, the ejector includes a driving nozzle, a suction chamber, and a mixing chamber; the first magnesium hydride bed chamber is communicated with the driving nozzle; the suction chamber is arranged around the outlet of the driving nozzle; the suction chamber is communicated with the second magnesium hydride bed chamber; both the driving nozzle and the suction chamber are communicated with the mixing chamber.

[0009] Preferably, the mixing chamber is connected to a hydrogen utilization system.

[0010] Preferably, the outlet cross-sectional area of the driving nozzle is smaller than the inlet cross-sectional area.

[0011] Preferably, a first pressure sensor is arranged between the first magnesium hydride bed chamber and the ejector; a second pressure sensor is arranged between the second magnesium hydride bed chamber and the ejector.

[0012] Preferably, a one-way valve is arranged between the ejector and the second magnesium hydride bed chamber.

[0013] In the second aspect, the present invention provides a magnesium hydride hydrogen storage method, including the following steps: Introduce heat transfer oil into the first magnesium hydride bed chamber, and dehydrogenate the first magnesium hydride bed chamber by heating with the heat transfer oil to generate first-pressure hydrogen. Introduce the heat transfer oil flowing out of the first magnesium hydride bed chamber into the second magnesium hydride bed chamber, and dehydrogenate the second magnesium hydride bed chamber by heating with the waste heat of the heat transfer oil to generate second-pressure hydrogen. Use the first-pressure hydrogen as a driving gas source and input it into the ejector, suck the second-pressure hydrogen through the ejector, and reduce the air pressure in the second magnesium hydride bed chamber. The first-pressure hydrogen and the second-pressure hydrogen are mixed in the ejector to form third-pressure hydrogen, and then output for utilization.

[0014] Preferably, the initial temperature of the heat transfer oil is 390-400 °C.

[0015] Preferably, the absolute pressure of the first-pressure hydrogen is greater than 0.3 MPa, the absolute pressure of the second-pressure hydrogen is lower than the standard atmospheric pressure, and the pressure of the third-pressure hydrogen is between the first-pressure hydrogen and the second-pressure hydrogen.

[0016] Compared with the prior art, the present invention has the following beneficial effects: In the present invention, the magnesium hydride bed layer is divided into two bed bins, and its "dual-bin configuration" enables the bed layer pressure to form high-pressure hydrogen and low-pressure hydrogen respectively according to the change of the heat exchange fluid temperature; through the ejector, the high-pressure hydrogen is used to pump and suck the low-pressure hydrogen, accelerating the dehydrogenation reaction of the bed layer on the outlet side of the heat exchange fluid, enabling the magnesium hydride hydrogen storage device to have high-efficiency heat exchange and high-capacity hydrogen release capabilities; compared with the traditional single-bed layer configuration, the hydrogen storage capacity of the device of the present invention can be increased by 30%. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for use in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0018] Figure 1 It is a schematic structural diagram of a magnesium hydride hydrogen storage device with a dual-bin configuration of the present invention; Wherein: 1. The first magnesium hydride bed bin; 2. The second magnesium hydride bed bin; 3. The ejector; 4. The first pressure sensor; 5. The second pressure sensor; 6. The check valve. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] In order to make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, 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.

[0020] Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed present invention, but merely represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0021] It should be noted that: similar reference numerals and letters indicate similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0022] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper", "lower", "horizontal", "inner", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the invention product is usually placed during use, it is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be construed as a limitation on the present invention. In addition, terms such as "first", "second", etc. are only used for distinguishing descriptions and cannot be construed as indicating or implying relative importance.

[0023] In addition, if the term "horizontal" appears, it does not mean that the component is required to be absolutely horizontal, but it can be slightly inclined. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but it can be slightly inclined.

[0024] In the description of the embodiments of the present invention, it should also be noted that unless otherwise clearly specified and limited, if terms such as "set", "installed", "connected", "connected" are 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 directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0025] The following further describes the present invention in detail with reference to the drawings: The first object of the present invention is to provide a hydrogen storage device with a double-chamber configuration of magnesium hydride, including a first magnesium hydride bed chamber 1 and a second magnesium hydride bed chamber 2 connected thereto; both the first magnesium hydride bed chamber 1 and the second magnesium hydride bed chamber 2 are connected to an ejector 3.

[0026] In the present invention, the magnesium hydride bed is divided into two bed compartments, with the gas path isolated between them and having independent hydrogen pressures. The high-temperature heat-conducting oil first heats the first magnesium hydride bed compartment 1, and the high temperature causes the hydrogen pressure generated in the first magnesium hydride bed compartment 1 to be higher, which is high-pressure hydrogen (the absolute pressure is generally greater than 0.3 MPa). The temperature of the heat-conducting oil coming out of the first magnesium hydride bed compartment 1 decreases, and then it heats the second magnesium hydride bed compartment 2. The lower temperature causes the hydrogen pressure generated in the second magnesium hydride bed compartment 2 to be lower, which is low-pressure hydrogen. Using the ejector 3, the high-pressure hydrogen is used to eject and pump the low-pressure hydrogen, which can help the second magnesium hydride bed compartment 2 to form an even lower reaction pressure, even lower than the atmospheric pressure, that is, a vacuum atmosphere. Furthermore, it accelerates the dehydrogenation reaction in the second magnesium hydride bed compartment 2 and overcomes the problem that the dehydrogenation reaction is difficult to continue due to the low temperature of the heat-conducting oil in the second magnesium hydride bed compartment 2. Through the vacuum atmosphere created by the ejector 3, the second magnesium hydride bed compartment 2 can absorb more heat from the heat-conducting oil (in a vacuum environment, the activation energy requirement for the decomposition of magnesium hydride decreases, and even at a lower temperature, the reaction can still proceed efficiently), realizing the cascaded and full utilization of thermal energy. After the high-pressure hydrogen and the low-pressure hydrogen are mixed by the ejector 3, medium-pressure hydrogen between the two is generated, which is convenient for downstream utilization.

[0027] The ejector 3 includes a driving nozzle, a suction chamber, and a mixing chamber; the first magnesium hydride bed compartment 1 is communicated with the driving nozzle; the suction chamber is arranged around the outlet of the driving nozzle; the suction chamber is communicated with the second magnesium hydride bed compartment 2; both the driving nozzle and the suction chamber are communicated with the mixing chamber.

[0028] The driving nozzle adopts a convergent flow channel design, and its outlet cross-sectional area is smaller than the inlet cross-sectional area. When the high-pressure hydrogen flows through the driving nozzle, a significant throttling effect is generated due to the sharp contraction of the flow cross-section. According to Bernoulli's equation and the continuity equation, at this time, the kinetic energy of the hydrogen increases significantly, the flow velocity can be increased to the subsonic range, and at the same time, the static pressure drops significantly, forming a strong low-pressure vortex area at the outlet of the driving nozzle; using the Venturi effect, the low-pressure hydrogen in the second magnesium hydride bed compartment 2 is automatically sucked through the surrounding suction chamber, and the mixing and pressurization of the two-pressure hydrogen can be realized without additional energy consumption; the mixing chamber enables the high-pressure hydrogen and the low-pressure hydrogen to be fully mixed and completes the conversion of kinetic energy-pressure energy, and finally outputs stable medium-pressure hydrogen.

[0029] The mixing chamber is connected to the hydrogen utilization system for the recovery and utilization of hydrogen.

[0030] A first pressure sensor 4 is provided between the first magnesium hydride bed bin 1 and the ejector 3; a second pressure sensor 5 is provided between the second magnesium hydride bed bin 2 and the ejector 3, realizing real-time and accurate monitoring of the hydrogen output pressures of the two magnesium hydride bed bins, promptly discovering performance differences or abnormalities in the bed bins, thereby enhancing the system safety and response speed. Specifically, if the pressure sensor on one side decreases abnormally, it may indicate problems such as local blockage, uneven hydrogen release, or material deterioration in the corresponding bed bin; if the pressure increases abnormally, it may reflect valve regulation failure or pipeline blockage. This dual-channel pressure monitoring mechanism greatly improves the system's fault diagnosis ability, enabling maintenance personnel to quickly locate problems and take adjustment measures to avoid a decrease in the overall hydrogen storage efficiency caused by the failure of a single-side bed bin.

[0031] A check valve 6 is provided between the ejector 3 and the second magnesium hydride bed bin 2. The opening direction of the check valve 6 is consistent with the low-pressure hydrogen flow direction, effectively preventing high-pressure hydrogen from flowing back into the second magnesium hydride bed bin 2, and also avoiding the problem of bed bin pressure imbalance caused by hydrogen backflow, significantly improving the safety and operation stability of the hydrogen storage system. At the same time, the check valve 6 is made of a special alloy material with high pressure resistance and hydrogen embrittlement resistance to ensure its long-term reliable operation.

[0032] The second object of the present invention is to provide a magnesium hydride hydrogen storage method, including the following steps: Pass heat-conducting oil at 390 - 400 °C into the first magnesium hydride bed bin 1, and dehydrogenate the first magnesium hydride bed bin 1 through heat-conducting oil heating to generate first-pressure hydrogen (high-pressure hydrogen, absolute pressure greater than 0.3 MPa); Pass the heat-conducting oil flowing out of the first magnesium hydride bed bin 1 into the second magnesium hydride bed bin 2, and dehydrogenate the second magnesium hydride bed bin 2 through the waste heat of the heat-conducting oil to generate second-pressure hydrogen (low-pressure hydrogen, absolute pressure lower than the standard atmospheric pressure); Input the first-pressure hydrogen as a driving gas source into the ejector 3, suck the second-pressure hydrogen through the ejector 3, and reduce the air pressure in the second magnesium hydride bed bin 2 to even lower than the atmospheric pressure to form a vacuum atmosphere; The first-pressure hydrogen and the second-pressure hydrogen are mixed in the ejector 3 to form third-pressure hydrogen with a pressure between the first-pressure hydrogen and the second-pressure hydrogen, and then output for utilization.

[0033] In the present invention, the magnesium hydride bed is divided into two independent bed bins, namely a high-pressure bin and a low-pressure bin. By using high-temperature heat-conducting oil for cascade heating, high-pressure hydrogen is generated in the first magnesium hydride bed bin 1 to drive the ejector 3, creating a vacuum atmosphere in the second magnesium hydride bed bin 2, significantly reducing the requirement for dehydrogenation activation energy, and enabling low-temperature waste heat to still efficiently drive the reaction. At the same time, the ejector 3 automatically mixes high-pressure and low-pressure hydrogen through the Venturi effect to achieve pressurization and output suitable medium-pressure hydrogen. The device of the present invention does not require additional energy consumption, solves the problems of reaction stagnation in the low-temperature bed layer and low thermal energy utilization efficiency of traditional magnesium hydride hydrogen storage devices, realizes the optimal matching of hydrogen pressure, and significantly improves the overall efficiency and practicality of the hydrogen storage system.

[0034] Exemplarily, the device of the present invention can be flexibly expanded into a multi-bin configuration according to the actual application scenario, such as a configuration design with 3 bins, 4 bins or more bins. In a multi-bin system, a multi-stage ejector 3 can be used to achieve a better hydrogen pressure regulation effect. Specifically, the medium-pressure hydrogen output by the previous-stage ejector 3 can be used as the driving gas source for the next stage. Through this cascading method, precise control of the pressure gradient of multiple bed bins can be achieved, further improving the cascade utilization efficiency of thermal energy. In addition, the heat exchange system of this device has a wide range of medium adaptability, not limited to heat-conducting oil as the heat exchange fluid, and other heat exchange media can also be selected according to different working temperature requirements, including but not limited to: air (suitable for low-temperature occasions), water / steam (suitable for medium-temperature ranges), molten salt (suitable for high-temperature stable heat transfer), and liquid metal (suitable for extremely high-temperature scenarios), etc.

[0035] Example 1 A magnesium hydride hydrogen storage device with a two-bin configuration, comprising: The first magnesium hydride bed bin 1, the inlet of the first magnesium hydride bed bin 1 is connected to the high-temperature heat-conducting oil supply pipeline, and the outlet is connected to the heat-conducting oil inlet of the second magnesium hydride bed bin 2 through a pipeline.

[0036] The second magnesium hydride bed bin 2, whose heat-conducting oil inlet receives the waste heat-conducting oil from the first magnesium hydride bed bin 1.

[0037] The ejector 3, which is arranged between the two bed bins, its high-pressure inlet is connected to the hydrogen outlet of the first magnesium hydride bed bin 1, and the low-pressure inlet is connected to the hydrogen outlet of the second magnesium hydride bed bin 2.

[0038] High-temperature dehydrogenation stage: Heat-conducting oil at 395°C is introduced into the first magnesium hydride bed bin 1, and the temperature of the first magnesium hydride bed bin 1 is maintained at 380 - 395°C, and dehydrogenation reaction generates high-pressure hydrogen.

[0039] After the heat-conducting oil flows out of the first magnesium hydride bed bin 1, its temperature drops to 340°C and enters the second magnesium hydride bed bin 2, heating the second magnesium hydride bed bin 2 to 320 - 335°C to trigger low-pressure dehydrogenation.

[0040] High-pressure hydrogen drives the ejector 3 at high pressure, sucking the low-pressure hydrogen in the second magnesium hydride bed bin 2, and reducing the internal pressure of the second magnesium hydride bed bin 2 to a vacuum state.

[0041] The pressure of the mixed third hydrogen is output for utilization.

[0042] Embodiment 2 A magnesium hydride hydrogen storage device with a three-bin configuration includes: The first magnesium hydride bed bin 1 receives high-temperature heat-conducting oil at 400 °C, and the temperature of the first magnesium hydride bed bin 1 is maintained at 380 - 400 °C to dehydrogenate and generate high-pressure hydrogen.

[0043] The second magnesium hydride bed bin 2 receives the heat-conducting oil flowing out of the first magnesium hydride bed bin 1 (the temperature drops to 350 °C), heats the second magnesium hydride bed bin 2 to 330 - 360 °C, and dehydrogenates to generate medium-pressure hydrogen.

[0044] The third magnesium hydride bed bin 3 receives the heat-conducting oil flowing out of the second magnesium hydride bed bin 2 (the temperature drops to 300 °C), heats the second magnesium hydride bed bin 2 to 280 - 320 °C, and dehydrogenates to generate low-pressure hydrogen.

[0045] The first ejector has its high-pressure inlet connected to the hydrogen outlet of the first magnesium hydride bed bin 1 and its low-pressure inlet connected to the hydrogen outlet of the second magnesium hydride bed bin 2, and mixes and outputs medium-high-pressure hydrogen.

[0046] The second ejector has its high-pressure inlet connected to the output end of the first ejector and its low-pressure inlet connected to the hydrogen outlet of the third magnesium hydride bed bin 3.

[0047] The mixed hydrogen is output for utilization.

[0048] High-temperature dehydrogenation stage: The heat-conducting oil flows through the first magnesium hydride bed bin 1, the second magnesium hydride bed bin 2, and the third magnesium hydride bed bin 3 in sequence for gradient heating.

[0049] The first ejector uses high-pressure hydrogen to suck medium-pressure hydrogen, reducing the pressure of the second bed bin. The second ejector further sucks low-pressure hydrogen, reducing the pressure of the third bed bin to a vacuum environment.

[0050] The mixed hydrogen is output for utilization after two-stage ejection.

[0051] The test results are shown in Table 1: Table 1 Hydrogen storage capacity cycle stability test

[0052] As can be seen from Table 1, after 10 cycles of the device of the present invention, the hydrogen storage capacity is 95% of the initial hydrogen storage capacity, while for the traditional single-bed system after 10 cycles, it is 65% of the initial hydrogen storage capacity. Compared with the traditional single-bed configuration, the hydrogen storage capacity of the device of the present invention can be increased by 30%.

[0053] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A magnesium hydride hydrogen storage device with a double-compartment configuration, characterized in that: It comprises a first magnesium hydride bed bin (1) and a second magnesium hydride bed bin (2) connected thereto; the first magnesium hydride bed bin (1) and the second magnesium hydride bed bin (2) are both connected to an ejector (3).

2. A magnesium hydride hydrogen storage device with a double-compartment configuration according to claim 1, characterized in that: The ejector (3) comprises a driving nozzle, a suction chamber and a mixing chamber; the first magnesium hydride bed chamber (1) is connected to the driving nozzle; the suction chamber is arranged around the driving nozzle outlet; the suction chamber is connected to the second magnesium hydride bed chamber (2); the driving nozzle and the suction chamber are both connected to the mixing chamber.

3. A dual-chamber magnesium hydride hydrogen storage device according to claim 2, characterized in that: The mixing chamber is connected to a hydrogen utilization system.

4. A dual-chamber magnesium hydride hydrogen storage device according to claim 2, characterized in that: The outlet cross-sectional area of ​​the driving nozzle is smaller than the inlet cross-sectional area.

5. A dual-chamber magnesium hydride hydrogen storage device according to claim 1, characterized in that: A first pressure sensor (4) is provided between the first magnesium hydride bed bin (1) and the ejector (3); and a second pressure sensor (5) is provided between the second magnesium hydride bed bin (2) and the ejector (3).

6. A dual-chamber magnesium hydride hydrogen storage device according to claim 1, characterized in that: A one-way valve (6) is provided between the ejector (3) and the second magnesium hydride bed chamber (2).

7. A method for storing hydrogen in magnesium hydride, characterized in that: The device according to any one of claims 1 to 6 comprises the following steps: Passing heat transfer oil into the first magnesium hydride bed chamber (1), heating the first magnesium hydride bed chamber (1) with the heat transfer oil to dehydrogenate the first magnesium hydride bed chamber (1) and generate hydrogen at a first pressure; Passing the heat transfer oil flowing out of the first magnesium hydride bed chamber (1) into the second magnesium hydride bed chamber (2), heating the second magnesium hydride bed chamber (2) with the residual heat of the heat transfer oil to dehydrogenate the second magnesium hydride bed chamber (2) and generate hydrogen at a second pressure; The first-pressure hydrogen is input as a driving gas source into an ejector (3), the second-pressure hydrogen is sucked through the ejector (3), and the gas pressure in the second magnesium hydride bed chamber (2) is reduced; The first pressure hydrogen and the second pressure hydrogen are mixed in the ejector (3) to form third pressure hydrogen, which is then output for use.

8. A method for storing hydrogen in magnesium hydride according to claim 7, characterized in that: The initial temperature of the heat transfer oil is 390-400°C.

9. A magnesium hydride hydrogen storage method according to claim 7, characterized in that: The absolute pressure of the first-pressure hydrogen is greater than 0.3 MPa, the absolute pressure of the second-pressure hydrogen is lower than the standard atmospheric pressure, and the pressure of the third-pressure hydrogen is between the first-pressure hydrogen and the second-pressure hydrogen.

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