A magnesium-based hydrogen-heat storage system based on MgO / MgCO3 thermochemical heat storage

Abstract

The application discloses a magnesium-based hydrogen-heat combined storage system based on MgO / MgCO3 thermochemical heat storage, and relates to the field of hydrogen energy, which comprises a magnesium-based solid-state hydrogen storage device (1), an MgO / MgCO3 heat storage device (2) wrapping the magnesium-based solid-state hydrogen storage device (1), a vacuum heat insulation layer (3) wrapping the magnesium-based solid-state hydrogen storage device (1) and the MgO / MgCO3 heat storage device (2), a hydrogen supply device (4) and a hydrogen utilization device (21) connected with the magnesium-based solid-state hydrogen storage device (1), and a carbon dioxide storage device (14) and a carbon dioxide supply device (18) connected with the MgO / MgCO3 heat storage device (2). The application utilizes the MgO / MgCO3 thermochemical heat storage reaction to efficiently store the heat released when the magnesium-based hydrogen storage material absorbs hydrogen and to supply heat when the magnesium-based hydrogen storage material releases hydrogen, so that the energy utilization rate of the magnesium-based hydrogen-heat combined storage system can be effectively improved, and the vacuum heat insulation layer can reduce heat dissipation of the system.

Description

TECHNICAL FIELD

[0001] The application relates to the field of hydrogen energy, in particular to a magnesium-based hydrogen thermal storage system based on MgO / MgCO3 thermochemical heat storage. BACKGROUND

[0002] Hydrogen energy has the characteristics of low carbon pollution, high weight energy density, and easy conversion with other energy, and is an important direction for sustainable development in China. Hydrogen storage and transportation is a key node connecting the hydrogen production end and the hydrogen use end, and efficient and safe hydrogen storage and transportation is a bottleneck for the hydrogen energy industry. Solid-state hydrogen storage technology has the advantages of high hydrogen storage density, high safety, low cost, and long cycle period.

[0003] Among solid-state hydrogen storage materials, magnesium-based hydrogen storage materials have high mass and volume hydrogen storage density (7.6wt%, 110 gL -1 ), high safety, normal temperature and pressure storage and transportation, abundant resources, and low cost, and are considered an important way to realize large-scale hydrogen storage and transportation. However, the magnesium-based hydrogen storage material involves a large heat change (~74.7 kJ mol -1 H2) in the hydrogen absorption and desorption process, and when it is filled in a solid-state hydrogen storage device for use, the heat released in the hydrogen absorption process is not effectively utilized and is easily dissipated, and a large amount of heat needs to be supplied by an external heat source in the hydrogen desorption process. This leads to low energy efficiency of the magnesium-based hydrogen storage system, hindering its popularization and application.

[0004] The reversible reaction of MgO / MgCO3 also involves a large heat change (~100.9 kJ mol -1 CO2), and its reaction temperature is similar to that of Mg / MgH2, and is a very potential thermochemical heat storage reaction pair for use with magnesium-based hydrogen storage materials. Magnesium oxide is a low-cost carbon dioxide adsorbent with a high theoretical adsorption capacity (24.8 mmol g -1 ) and medium-temperature adsorption and desorption (200℃-400℃). However, the actual adsorption capacity of pure magnesium oxide is very small (<1 mmol g -1 ), and the reaction kinetics is very slow. By doping and compounding alkali metal nitrates (such as LiNO3, NaNO3, and KNO3), the actual capacity and kinetic performance of the magnesium oxide adsorbing carbon dioxide can be effectively improved, and the heat storage performance of the MgO / MgCO3 reaction pair can be improved.

[0005] Therefore, the person skilled in the art is committed to developing a MgO / MgCO3 thermochemical heat storage reaction pair that can effectively store the heat released when the magnesium-based hydrogen storage material absorbs hydrogen and supply heat when the magnesium-based hydrogen storage material desorbs hydrogen, so as to effectively improve the energy utilization rate of the magnesium-based hydrogen thermal storage system and lay a foundation for developing and applying a magnesium-based hydrogen storage system that is efficient, safe, and low in energy consumption. SUMMARY

[0006] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present application is that the heat released in the hydrogen absorption process of the existing magnesium-based solid-state hydrogen storage device is not effectively utilized, a large amount of heat needs to be supplied by an external heat source in the hydrogen release process, and the system energy efficiency is low. In the MgO / MgCO3 thermochemical heat storage reaction pair, the actual adsorption capacity of pure magnesium oxide to carbon dioxide is low, and the heat storage capacity is limited. The magnesium-based solid-state hydrogen storage device generally uses a metal shell such as steel and iron, and the heat dissipation of the device is serious during use.

[0007] The present application utilizes the MgO / MgCO3 thermochemical heat storage reaction pair for hydrogen-heat storage, and the magnesium oxide-based thermochemical heat storage material efficiently stores the heat released when the magnesium-based hydrogen storage material absorbs hydrogen, and quickly releases heat when the magnesium-based hydrogen storage material needs heat supply during hydrogen release, thereby improving the system energy efficiency. By using a single or doped composite alkali metal nitrate (such as 10wt% NaNO3, 10wt% KNO3, 10wt% LiNO3, 5wt% NaNO3-5wt% KNO3, 5wt% NaNO3-5wt% LiNO3, 5wt% KNO3-5wt% LiNO3) in a certain mass ratio, the actual capacity and kinetic performance of the magnesium oxide to adsorb carbon dioxide are improved. When the temperature reaches the melting point of the alkali metal nitrate (about 300℃), the nitrate will become liquid, promoting the reaction of magnesium oxide and carbon dioxide, improving the adsorption and desorption capacity and kinetics, and further improving the heat storage performance. A vacuum thermal insulation layer is designed and constructed on the outermost layer of the magnesium-based solid-state hydrogen storage device to reduce heat dissipation during use. The thermal conductivity of vacuum is basically zero, and there is no heat convection in vacuum. By designing and constructing a vacuum thermal insulation layer on the outermost layer of the magnesium-based solid-state hydrogen storage device, the heat dissipation loss due to heat conduction and heat convection of the device can be effectively reduced.

[0008] To achieve the above-mentioned purpose, the present application provides a magnesium-based hydrogen-heat storage system based on MgO / MgCO3 thermochemical heat storage, which comprises a magnesium-based solid-state hydrogen storage device 1;

[0009] The MgO / MgCO3 heat storage device 2 wraps the magnesium-based solid-state hydrogen storage device 1;

[0010] The vacuum thermal insulation layer 3 wraps the magnesium-based solid-state hydrogen storage device 1 and the MgO / MgCO3 heat storage device 2;

[0011] The hydrogen supply device 4 and the hydrogen utilization device 21 connected with the magnesium-based solid-state hydrogen storage device 1;

[0012] The carbon dioxide storage device 14 and the carbon dioxide supply device 18 connected with the MgO / MgCO3 heat storage device 2.

[0013] Further, the magnesium-based solid-state hydrogen storage device 1 and the MgO / MgCO3 heat storage device 2 have a heat transfer structure, preferably the heat transfer structure is a heat transfer fin made of a good thermal conductive metal material (such as copper, stainless steel) or carbon material.

[0014] Further, the hydrogen supply device 4 is connected to the magnesium-based solid-state hydrogen storage device 1 in sequence through the first pressure reducing valve 5, the hydrogen metering device 6, the first pressure sensor 7, and the first valve 8.

[0015] Further, the hydrogen using device 21 is connected to the magnesium-based solid-state hydrogen storage device 1 in sequence through the sixth valve 20, the back pressure valve 19, the hydrogen metering device 6, and the first valve 8; and / or in sequence through the sixth valve 20, the second vacuum pump 23, the seventh valve 24, the hydrogen metering device 6, and the first valve 8; and the first pressure sensor 7 is arranged between the hydrogen metering device 6 and the first valve 8.

[0016] Further, the MgO / MgCO3 heat storage device 2 is connected to the carbon dioxide storage device 14 in sequence through the second valve 9, the carbon dioxide metering device 11, the third valve 12, and the fourth valve 13; and / or in sequence through the second valve 9, the carbon dioxide metering device 11, the fifth valve 16, the first vacuum pump 15, the fourth valve 13, and the carbon dioxide storage device 14; and the carbon dioxide storage device 14 can supply carbon dioxide to the carbon dioxide supply device 18 through the booster pump 17, and the carbon dioxide supply device 18 supplies carbon dioxide to the MgO / MgCO3 heat storage device 2 in sequence through the second pressure reducing valve 22, the carbon dioxide metering device 11, and the second valve 9; and the second pressure sensor 10 is arranged between the second valve 9 and the carbon dioxide metering device 11.

[0017] Further, the first valve 8 and the second valve 9 should have a flow regulating function.

[0018] Preferably, the magnesium-based solid-state hydrogen storage device 1 is filled with magnesium-nickel-based hydrogen storage alloy hydrogen storage material.

[0019] Preferably, the MgO / MgCO3 heat storage device 2 is filled with magnesium oxide heat storage material doped with single or mixed alkali metal nitrate (such as 10wt% NaNO3, 10wt% KNO3, 10wt% LiNO3, 5wt% NaNO3-5wt% KNO3, 5wt% NaNO3-5wt% LiNO3, 5wt% KNO3-5wt% LiNO3) in a certain mass ratio, and the mass ratio of hydrogen storage material to heat storage material is between 1:2 and 1:10.

[0020] Preferably, the carbon dioxide storage device 14 can use gaseous or liquid direct storage or MOF, activated carbon, etc. for adsorption storage.

[0021] In the preferred embodiment of the present application, when the system is first used, the magnesium-based solid-state hydrogen storage device 1, the MgO / MgCO3 heat storage device 2, and the vacuum insulation layer 3 are first vacuumized. Then, the MgO / MgCO3 heat storage device 2 is preheated to 500°C, vacuumized for 3 hours to remove impurities, and then carbonated with carbon dioxide to fully carbonize the magnesium oxide.

[0022] When the system needs to absorb hydrogen, the magnesium-based solid-state hydrogen storage device 1 and the MgO / MgCO3 heat storage device 2 are preheated to 350°C. Then, the hydrogen supply device 4 supplies hydrogen, which flows through the first pressure reducing valve 5, and then sequentially flows through the hydrogen gas metering device 6, the first pressure sensor 7, and the first valve 8, and is supplied to the magnesium-based solid-state hydrogen storage device 1 at a constant flow rate and a pressure greater than the plateau pressure of the magnesium-based hydrogen storage material. The magnesium-based hydrogen storage material in the magnesium-based solid-state hydrogen storage device 1 undergoes a hydrogen absorption reaction and releases heat, and the released heat is conducted to the MgO / MgCO3 heat storage device 2 through the heat transfer structure. The magnesium carbonate in the MgO / MgCO3 heat storage device 2 is decomposed by heat, and the decomposed carbon dioxide flows through the second valve 9, and then sequentially flows through the second pressure sensor 10, the carbon dioxide gas metering device 11, and enters the carbon dioxide collection device 14 through the third valve 12 and the fourth valve 13. When the carbon dioxide pressure is lower than 1 bar, the third valve 12 is closed, the first vacuum pump 15 and the fifth valve 16 are opened, and the remaining carbon dioxide is pumped to the carbon dioxide collection device 14. The carbon dioxide stored in the carbon dioxide collection device 14 can be pressurized by the booster pump 17 and supplied to the carbon dioxide supply device 18 for use in carbonizing the magnesium oxide.

[0023] When the system needs to release hydrogen, the magnesium-based solid-state hydrogen storage device 1 and the MgO / MgCO3 heat storage device 2 are preheated to 300°C. Then, the first valve 8 is opened, and the released hydrogen sequentially flows through the first pressure sensor 7 and the hydrogen gas metering device 6, and flows to the hydrogen using device 21 through the back pressure valve 19 and the sixth valve 20. At the same time, the carbon dioxide supply device 18 supplies carbon dioxide, which flows through the second pressure reducing valve 22 at a pressure greater than or equal to 2 bar, and then sequentially flows through the carbon dioxide gas metering device 11 and the second pressure sensor 10, and enters the MgO / MgCO3 heat storage device 2 through the second valve 9, carbonizes the magnesium oxide and releases heat, and the released heat is conducted to the magnesium-based solid-state hydrogen storage device 1 through the heat transfer structure to support the absorption of heat required during the hydrogen release process. When the hydrogen release pressure is lower than 1.5 bar, the back pressure valve 19 is closed, the second vacuum pump 23 and the seventh valve 24 are opened, and the remaining hydrogen is quickly pumped out for use by the hydrogen using device 21.

[0024] Technical effects

[0025] 1. In this invention, when the magnesium-based hydrogen storage material absorbs hydrogen and releases heat, the heat is transferred to the magnesium oxide-based thermochemical thermal storage material via thermal conduction. Magnesium carbonate decomposes and absorbs the heat released from hydrogen storage, achieving efficient chemical thermal storage. When the magnesium-based hydrogen storage material needs heat to release hydrogen, carbon dioxide is introduced into the magnesium oxide-based thermochemical thermal storage material to release heat, which is then transferred back to the magnesium-based hydrogen storage material via thermal conduction. By utilizing the MgO / MgCO3 thermochemical thermal storage reaction pair, hydrogen-thermal co-storage of the magnesium-based solid-state hydrogen storage system is achieved, enabling thermal self-sufficiency management and improving the system's energy utilization rate.

[0026] 2. This invention utilizes alkali metal nitrate-doped composite magnesium oxide to achieve high thermal storage performance of the MgO / MgCO3 thermochemical thermal storage reaction pair, making it more suitable for hydrogen thermal storage.

[0027] 3. This invention utilizes a vacuum insulation layer to achieve low heat dissipation in a magnesium-based solid-state hydrogen storage system, thereby improving the system's hydrogen thermal co-storage performance. Attached Figure Description

[0028] The following will further explain the concept, specific structure, and technical effects of the present invention in conjunction with the accompanying drawings, so as to fully understand the purpose, features, and effects of the present invention.

[0029] Figure 1 This is a schematic diagram of a magnesium-based hydrogen thermal co-storage system based on MgO / MgCO3 thermochemical thermal storage, according to a preferred embodiment of the present invention.

[0030] Reference numerals in the attached figures: 1. Magnesium-based solid-state hydrogen storage device; 2. MgO / MgCO3 thermal storage device; 3. Vacuum insulation layer; 4. Hydrogen supply device; 5. First pressure reducing valve; 6. Hydrogen metering device; 7. First pressure sensor; 8. First valve; 9. Second valve; 10. Second pressure sensor; 11. Carbon dioxide metering device; 12. Third valve; 13. Fourth valve; 14. Carbon dioxide storage device; 15. First vacuum pump; 16. Fifth valve; 17. Booster pump; 18. Carbon dioxide supply device; 19. Back pressure valve; 20. Sixth valve; 21. Hydrogen consumption device; 22. Second pressure reducing valve; 23. Second vacuum pump; 24. Seventh valve.

[0031] Figure 2 This is a schematic cross-sectional view of the hydrogen thermal storage tank of a magnesium-based hydrogen thermal storage system based on MgO / MgCO3 thermochemical thermal storage, according to a preferred embodiment of the present invention.

[0032] Reference numerals: 1. Magnesium-based solid-state hydrogen storage device; 2. MgO / MgCO3 thermal storage device; 3. Vacuum insulation layer; 25. Heat transfer fins Detailed Implementation

[0033] The following description, with reference to the accompanying drawings, illustrates several preferred embodiments of the present invention to make its technical content clearer and easier to understand. The present invention can be embodied in many different forms, and the scope of protection of the present invention is not limited to the embodiments mentioned herein.

[0034] In the accompanying drawings, components with the same structure are indicated by the same numerical designation, and components with similar structures or functions are indicated by similar numerical designations. The dimensions and thicknesses of each component shown in the drawings are arbitrary, and the present invention does not limit the dimensions and thicknesses of each component. To make the illustrations clearer, the thickness of some components has been appropriately exaggerated in the drawings.

[0035] like Figure 1 As shown, the present invention provides a magnesium-based hydrogen thermal co-storage system based on MgO / MgCO3 thermochemical thermal storage, which includes a magnesium-based solid hydrogen storage device 1.

[0036] A MgO / MgCO3 thermal storage device 2 encapsulating a magnesium-based solid hydrogen storage device 1;

[0037] Vacuum insulation layer 3 encapsulating magnesium-based solid hydrogen storage device 1 and MgO / MgCO3 thermal storage device 2;

[0038] Hydrogen supply device 4 and hydrogen consumption device 21 are connected to the magnesium-based solid hydrogen storage device 1;

[0039] A carbon dioxide storage device 14 and a carbon dioxide supply device 18 are connected to the MgO / MgCO3 thermal storage device 2.

[0040] The magnesium-based solid hydrogen storage device 1 and the MgO / MgCO3 thermal storage device 2 have a heat transfer structure, and the preferred heat transfer structure is a heat transfer fin.

[0041] The hydrogen supply device 4 is connected to the magnesium-based solid hydrogen storage device 1 in sequence via the first pressure reducing valve 5, the hydrogen metering device 6, and the first valve 8; the hydrogen consumption device 21 is connected to the magnesium-based solid hydrogen storage device 1 in sequence via the sixth valve 20, the back pressure valve 19, the hydrogen metering device 6, and the first valve 8; and / or is connected to the magnesium-based solid hydrogen storage device 1 in sequence via the sixth valve 20, the second vacuum pump 23, the seventh valve 24, the hydrogen metering device 6, and the first valve 8; a first pressure sensor 7 is provided between the hydrogen metering device 6 and the first valve 8.

[0042] The MgO / MgCO3 heat storage device 2 is connected with the carbon dioxide storage device 14 through the second valve 9, the carbon dioxide gas metering device 11, the third valve 12, the fourth valve 13 in sequence; and / or connected with the carbon dioxide storage device 14 through the second valve 9, the carbon dioxide gas metering device 11, the fifth valve 16, the first vacuum pump 15, the fourth valve 13 in sequence; the carbon dioxide storage device 14 can supply carbon dioxide to the carbon dioxide supply device 18 through the booster pump 17, and the carbon dioxide supply device 18 supplies carbon dioxide to the MgO / MgCO3 heat storage device 2 through the second pressure reducing valve 22, the carbon dioxide gas metering device 11, the second valve 9 in sequence; the second pressure sensor 10 is arranged between the second valve 9 and the carbon dioxide gas metering device 11.

[0043] Embodiment 1

[0044] In this embodiment, a magnesium-based hydrogen heat storage system based on MgO / MgCO3 thermochemical heat storage includes a magnesium-based solid-state hydrogen storage device 1, a MgO / MgCO3 heat storage device 2, a vacuum insulation layer 3, a hydrogen supply device 4, a first pressure reducing valve 5, a hydrogen gas metering device 6, a first pressure sensor 7, a first valve 8, a second valve 9, a second pressure sensor 10, a carbon dioxide gas metering device 11, a third valve 12, a fourth valve 13, a carbon dioxide storage device 14, a first vacuum pump 15, a fifth valve 16, a booster pump 17, a carbon dioxide supply device 18, a back pressure valve 19, a sixth valve 20, a hydrogen device 21, a second pressure reducing valve 22, a second vacuum pump 23, and a seventh valve 24 (as shown in Figure 1 The first valve 8 and the second valve 9 should have a flow regulating function. The magnesium-based solid-state hydrogen storage device 1 is filled with magnesium-nickel-based hydrogen storage alloy, and the MgO / MgCO3 heat storage device 2 is filled with 10wt% NaNO3 or 10wt% KNO3 doped composite magnesium oxide, and the mass ratio of the hydrogen storage material to the heat storage material is 1:5. The carbon dioxide storage device 14 can be directly stored in gaseous or liquid state or stored by adsorption with MOF, activated carbon and other materials. There are heat transfer fins 25 between the magnesium-based solid-state hydrogen storage device 1 and the MgO / MgCO3 heat storage device 2, and the devices are preheated by an electric heating rod.

[0045] When the system is used for the first time, first, the magnesium-based solid-state hydrogen storage device 1, the MgO / MgCO3 heat storage device 2, and the vacuum insulation layer 3 are subjected to vacuumizing operation. Then, the MgO / MgCO3 heat storage device 2 is preheated to 500°C, impurities are removed by vacuumizing for 3h, and then carbon dioxide is introduced to fully carbonize the magnesium oxide.

[0046] When the system needs to absorb hydrogen, the magnesium-based solid hydrogen storage device 1 and the MgO / MgCO3 heat storage device 2 are preheated to 350°C. Then, the hydrogen supply device 4 supplies hydrogen, which flows through the first pressure reducing valve 5, and then through the hydrogen metering device 6, the first pressure sensor 7, and the first valve 8, into the magnesium-based solid hydrogen storage device 1 at a constant flow rate and a pressure greater than the plateau pressure of the magnesium-based hydrogen storage material. The magnesium-based hydrogen storage material in the magnesium-based solid hydrogen storage device 1 undergoes a hydrogen absorption reaction and releases heat, which is conducted to the MgO / MgCO3 heat storage device 2 through the heat transfer fins 25. The magnesium carbonate in the MgO / MgCO3 heat storage device 2 decomposes upon heating, and the decomposed carbon dioxide flows through the second valve 9, and then through the second pressure sensor 10, the carbon dioxide metering device 11, the third valve 12, and the fourth valve 13 into the carbon dioxide collection device 14. When the carbon dioxide pressure is lower than 1 bar, the third valve 12 is closed, the first vacuum pump 15 and the fifth valve 16 are opened, and the remaining carbon dioxide is pumped into the carbon dioxide collection device 14. The carbon dioxide stored in the carbon dioxide collection device 14 can be pressurized by the booster pump 17 and supplied to the carbon dioxide supply device 18 for use in carbonating magnesia.

[0047] When the system needs to release hydrogen, the magnesium-based solid hydrogen storage device 1 and the MgO / MgCO3 heat storage device 2 are preheated to 300°C. Then, the first valve 8 is opened, and the released hydrogen flows through the first pressure sensor 7 and the hydrogen metering device 6, and then flows through the back pressure valve 19 and the sixth valve 20 to the hydrogen using device 21. At the same time, the carbon dioxide supply device 18 supplies carbon dioxide, which flows through the second pressure reducing valve 22 at a pressure greater than or equal to 2 bar, and then flows through the carbon dioxide metering device 11 and the second pressure sensor 10, and then flows through the second valve 9 into the MgO / MgCO3 heat storage device 2 to carbonate magnesia and release heat, which is conducted to the magnesium-based solid hydrogen storage device 1 through the heat transfer fins 25 to support the absorption of heat required during the hydrogen release process. When the hydrogen release pressure is lower than 1.5 bar, the back pressure valve 19 is closed, the second vacuum pump 23 and the seventh valve 24 are opened, and the remaining hydrogen is quickly pumped out for use by the hydrogen using device 21.

[0048] Example 2

[0049] In the present embodiment, a magnesium-based hydrogen thermal storage system based on MgO / MgCO3 thermochemical heat storage comprises a magnesium-based solid-state hydrogen storage device 1, a MgO / MgCO3 heat storage device 2, a vacuum insulation layer 3, a hydrogen supply device 4, a first pressure reducing valve 5, a hydrogen metering device 6, a first pressure sensor 7, a first valve 8, a second valve 9, a second pressure sensor 10, a carbon dioxide metering device 11, a third valve 12, a fourth valve 13, a carbon dioxide storage device 14, a first vacuum pump 15, a fifth valve 16, a booster pump 17, a carbon dioxide supply device 18, a back pressure valve 19, a sixth valve 20, a hydrogen-using device 21, a second pressure reducing valve 22, a second vacuum pump 23, and a seventh valve 24 (as shown in Figure 1 The first valve 8 and the second valve 9 should have a flow regulating function. The magnesium-based solid-state hydrogen storage device 1 is filled with a magnesium-nickel-based hydrogen storage alloy, the MgO / MgCO3 heat storage device 2 is filled with 5wt% NaNO3-5wt% LiNO3 or 5wt% KNO3-5wt% LiNO3 doped composite magnesium oxide, and the mass ratio of the hydrogen storage material to the heat storage material is 1:3. The carbon dioxide storage device 14 can be directly stored in a gaseous or liquid state or stored by adsorption using MOF, activated carbon or other materials. There are heat transfer fins 25 between the magnesium-based solid-state hydrogen storage device 1 and the MgO / MgCO3 heat storage device 2, and the devices are preheated by an electric heating rod.

[0050] When the system is used for the first time, first, the magnesium-based solid-state hydrogen storage device 1, the MgO / MgCO3 heat storage device 2, and the vacuum insulation layer 3 are subjected to a vacuumizing operation. Then, the MgO / MgCO3 heat storage device 2 is preheated to 500°C, impurities are removed by vacuumizing for 3h, and then carbon dioxide is introduced to fully carbonize the magnesium oxide.

[0051] When the system needs to absorb hydrogen, the magnesium-based solid-state hydrogen storage device 1 and the MgO / MgCO3 heat storage device 2 are preheated to 350℃. Then, the hydrogen supply device 4 supplies hydrogen, and the supplied hydrogen flows through the first pressure reducing valve 5, and then sequentially flows through the hydrogen metering device 6, the first pressure sensor 7, and the first valve 8, and is supplied to the magnesium-based solid-state hydrogen storage device 1 at a constant flow rate and a pressure greater than the plateau pressure of the magnesium-based hydrogen storage material. The magnesium-based hydrogen storage material in the magnesium-based solid-state hydrogen storage device 1 undergoes a hydrogen absorption reaction and releases heat, and the released heat is conducted to the MgO / MgCO3 heat storage device 2 through the heat transfer fins 25. The magnesium carbonate in the MgO / MgCO3 heat storage device 2 is decomposed by heat, and the decomposed carbon dioxide flows through the second valve 9, and then sequentially flows through the second pressure sensor 10 and the carbon dioxide metering device 11, and enters the carbon dioxide collection device 14 through the third valve 12 and the fourth valve 13. When the carbon dioxide pressure is lower than 1 bar, the third valve 12 is closed, the first vacuum pump 15 and the fifth valve 16 are opened, and the remaining carbon dioxide is pumped to the carbon dioxide collection device 14. The stored carbon dioxide in the carbon dioxide collection device 14 can be pressurized by the booster pump 17 and supplied to the carbon dioxide supply device 18 for use of carbonated magnesia.

[0052] When the system needs to release hydrogen, the magnesium-based solid-state hydrogen storage device 1 and the MgO / MgCO3 heat storage device 2 are preheated to 300℃. Then, the first valve 8 is opened, and the released hydrogen sequentially flows through the first pressure sensor 7 and the hydrogen metering device 6, and flows to the hydrogen using device 21 through the back pressure valve 19 and the sixth valve 20. At the same time, the carbon dioxide supply device 18 supplies carbon dioxide, and the supplied carbon dioxide flows through the second pressure reducing valve 22 at a pressure greater than or equal to 2 bar, and then sequentially flows through the carbon dioxide metering device 11 and the second pressure sensor 10, and enters the MgO / MgCO3 heat storage device 2 through the second valve 9, carbonates the magnesia and releases heat, and the released heat is conducted to the magnesium-based solid-state hydrogen storage device 1 through the heat transfer fins 25 to support the heat absorption required in the hydrogen release process. When the hydrogen release pressure is lower than 1.5 bar, the back pressure valve 19 is closed, the second vacuum pump 23 and the seventh valve 24 are opened, and the remaining hydrogen is quickly pumped out for use of the hydrogen using device 21.

[0053] The magnesium-based hydrogen-heat storage system based on the MgO / MgCO3 thermochemical heat storage of the application effectively stores the heat released in the hydrogen absorption process of the magnesium-based hydrogen storage material, and quickly supplies the heat when the magnesium-based hydrogen storage material releases hydrogen, thereby realizing efficient hydrogen-heat storage of the magnesium-based solid-state hydrogen storage system, and the energy utilization rate of the system working condition is not less than 90%. The system is easy to implement and has simple and clear operation logic, solves the difficulty of low energy utilization rate of the magnesium-based hydrogen storage system, lays a foundation for developing and applying high-efficiency, safe and low-energy-consumption magnesium-based hydrogen storage systems, and the market scale can reach hundreds of billions of yuan.

[0054] The preferred embodiments of the present application have been described above in detail. It should be understood that modifications and variations to the preferred embodiments could be made by those skilled in the art without departing from the spirit and scope of the application. Accordingly, it is intended that there be included within the scope of the application, all such modifications and variations as would be apparent to those skilled in the art upon reading this disclosure. It is intended to obtain for the inventors such patent rights as are available for any patent granted on the present application.

Claims

1. A magnesium-based thermo-hydrogen storage system based on MgO / MgCC thermal chemical heat storage, characterized in that, It comprises a magnesium-based solid-state hydrogen storage device (1); The MgO / MgCO3 heat storage device (2) wraps the magnesium-based solid-state hydrogen storage device (1); The vacuum insulation layer (3) wraps the magnesium-based solid-state hydrogen storage device (1) and the MgO / MgCO3 heat storage device (2); The hydrogen supply device (4) and the hydrogen utilization device (21) are connected with the magnesium-based solid-state hydrogen storage device (1); The carbon dioxide storage device (14) and the carbon dioxide supply device (18) are connected with the MgO / MgCO3 heat storage device (2); The MgO / MgCO3 heat storage device (2) is filled with magnesium oxide heat storage material doped with single or mixed composite alkali metal nitrate in a certain mass ratio; The MgO / MgCO3 heat storage device (2) is connected with the carbon dioxide storage device (14) through the second valve (9), the carbon dioxide gas metering device (11), the third valve (12), the fourth valve (13) in sequence; and / or connected with the carbon dioxide storage device (14) through the second valve (9), the carbon dioxide gas metering device (11), the fifth valve (16), the first vacuum pump (15), the fourth valve (13) in sequence; The carbon dioxide storage device (14) supplies carbon dioxide to the carbon dioxide supply device (18) through the booster pump (17), and the carbon dioxide supply device (18) supplies carbon dioxide to the MgO / MgCO3 heat storage device (2) through the second pressure reducing valve (22), the carbon dioxide gas metering device (11), and the second valve (9) in sequence; a second pressure sensor (10) is arranged between the second valve (9) and the carbon dioxide gas metering device (11).

2. The MgO / MgCC -based thermo-chemical heat storage based magnesium based hydrogen heat storage system as claimed in claim 1, wherein, The magnesium-based solid-state hydrogen storage device (1) and the MgO / MgCO3 heat storage device (2) have a heat transfer structure.

3. The MgO / MgCC -based thermo-chemical heat storage based magnesium based hydrogen heat storage system as claimed in claim 2, wherein, The heat transfer structure between the magnesium-based solid-state hydrogen storage device (1) and the MgO / MgCO3 heat storage device (2) is a heat transfer fin structure.

4. The MgO / MgCC -based thermo-chemical heat storage based magnesium based hydrogen heat storage system as claimed in claim 1, wherein, The hydrogen supply device (4) is connected with the magnesium-based solid-state hydrogen storage device (1) through the first pressure reducing valve (5), the hydrogen gas metering device (6), the first pressure sensor (7), and the first valve (8) in sequence.

5. The MgO / MgCC -based thermo-chemical heat storage based magnesium based hydrogen heat storage system as claimed in claim 1, wherein, The hydrogen utilization device (21) is connected with the magnesium-based solid-state hydrogen storage device (1) through the sixth valve (20), the back pressure valve (19), the hydrogen gas metering device (6), and the first valve (8) in sequence; and / or connected with the magnesium-based solid-state hydrogen storage device (1) through the sixth valve (20), the second vacuum pump (23), the seventh valve (24), the hydrogen gas metering device (6), and the first valve (8) in sequence; a first pressure sensor (7) is arranged between the hydrogen gas metering device (6) and the first valve (8).

6. A magnesium based thermochemical heat storage system based on MgO / MgCC thermal storage according to any one of claims 1, 4 and 5, characterized in that, The first valve (8) and the second valve (9) have a flow regulating function.

7. The MgO / MgCC -based thermo-chemical heat storage based magnesium based hydrogen heat storage system as claimed in claim 1, wherein, The magnesium-based solid-state hydrogen storage device (1) is filled with magnesium-nickel-based hydrogen storage alloy hydrogen storage material.

8. The MgO / MgCC -based thermo-chemical heat storage based magnesium based hydrogen heat storage system as claimed in claim 7, wherein, The mass ratio of the hydrogen storage material to the heat storage material is between 1:2 and 1:

10.

9. The MgO / MgCC -based thermo-chemical heat storage based magnesium based hydrogen heat storage system as claimed in claim 7, wherein, The mass ratio of the hydrogen storage material to the heat storage material is between 1:3 and 1:

5.

10. The MgO / MgCC -based thermo-chemical heat storage based magnesium based hydrogen heat storage system as claimed in claim 1, wherein, The carbon dioxide storage device (14) uses gaseous or liquid direct storage or MOF or activated carbon material adsorption storage.

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