Liquid hydrogen storage system

Abstract

The utility model relates to a liquid hydrogen storage system which comprises an integrated hydrogen storage device and a hydrogen storage medium, the integrated hydrogen storage device comprises a liquid storage tank for storing a hydrogen storage medium, a gas storage tank for storing hydrogen, a reactor connected with the output ends of the liquid storage tank and the gas storage tank, a condenser connected with the reactor, a gas-liquid separator connected with the output end of the condenser, a gas compressor and a gas buffer tank, and one or more unsaturated aromatic hydrocarbons or heterocyclic unsaturated compounds with a saturated vapor pressure of more than 1 kPa and a temperature of 20 DEG C. The gas-phase storage medium of the liquid hydrogen storage system sequentially passes through the condenser, the gas-liquid separator, the gas compressor and the gas buffer tank, so that a hydrogen pressurizing, cooling and refluxing process is realized, a liquid hydrogen storage material can be effectively recycled, and the purity of hydrogen can be ensured.

Description

Technical Field

[0001] This utility model relates to the field of hydrogen storage, and in particular to a liquid hydrogen storage system. Background Technology

[0002] The industrial hydrogen energy chain for chlorine can be divided into three basic aspects: production, storage, and utilization. Currently, hydrogen is mainly produced through the reforming of fossil fuels, but in the future, it may be produced by electrolyzing water using electricity generated from renewable energy sources. After production, hydrogen can be utilized through fuel cells or internal combustion engines; lower-cost fuel cells are also under development.

[0003] However, there are still many problems to be solved in the efficient storage of hydrogen. Among the three conversion methods that can overcome the difficulties in storing hydrogen, reversible hydrogen storage through chemical bonds is considered a promising solution.

[0004] Chemically bonded reversible hydrogen storage refers to the process where a hydrogen-poor molecule undergoes hydrogenation at one location, providing abundant and inexpensive hydrogen to corresponding hydrogen-rich molecules. These hydrogen-rich molecules can be stored long-term and transported using existing energy transmission infrastructure. At the point of use, hydrogen is released through catalytic dehydrogenation, and the hydrogen-poor molecule can then return to each hydrogen supply point for re-hydrogenation and energy storage. In this "chemical storage," liquid-phase hydrogen storage materials are more advantageous than gas-phase materials, hence the name liquid hydrogen storage carrier (LOHC) materials. LOHC materials are mostly high-boiling-point organic molecules that readily undergo catalytic reversible dehydrogenation.

[0005] CN104555914A discloses a liquid hydrogen storage system. This system comprises at least two different hydrogen storage components, which are unsaturated aromatic hydrocarbons or heterocyclic unsaturated compounds, and at least one of these components is a low-melting-point compound with a melting point below 80°C. This liquid hydrogen storage system is essentially a multi-component mixed liquid fused heterocyclic aromatic hydrocarbon hydrogen storage system. This invention, by mixing two or more fused heterocyclic unsaturated compounds, forms a mixed system with a eutectic point at least lower than the melting point of one of the components.

[0006] CN109704274A discloses a feedstock system for organic liquid hydrogen storage. A component is cut from the distillate oil of aromatic petroleum or coal-based petroleum as a hydrogen storage material, and this material is hydrogenated to obtain the feedstock system for organic liquid hydrogen storage; alternatively, a component is cut from the distillate oil of naphthenic petroleum as a feedstock system for organic liquid hydrogen storage; or a mixture of the above two methods is used as the feedstock system for organic liquid hydrogen storage technology. This feedstock system is widely available, inexpensive, liquid at room temperature, and convenient to store and transport, showing strong application prospects.

[0007] CN109353987A discloses a liquid hydrogen storage material and its preparation method. This liquid hydrogen storage material includes a carbazole-based hydrogen storage component and a low-melting-point additive with a high thermal conductivity. The carbazole-based hydrogen storage component is at least one selected from carbazole, N-methylcarbazole, N-ethylcarbazole, N-n-propylcarbazole, N-isopropylcarbazole, or N-n-butylcarbazole. The low-melting-point thermally conductive additive component is at least one selected from dibenzyltoluene or hydrogenated terphenyl. This novel liquid hydrogen storage material is formed by mixing a high-melting-point carbazole-based hydrogen storage material with a low-melting-point thermally conductive additive. The resulting mixture has a eutectic point at least lower than the melting point of one of the components, allowing the overall melting point of the hydrogen storage material to drop below 0°C. Simultaneously, the low-melting-point thermally conductive additive has a high thermal conductivity; after mixing with the carbazole-based hydrogen storage material, the thermal conductivity of the resulting mixture is higher than that of the carbazole-based hydrogen storage material. During dehydrogenation, this allows the entire hydrogen storage material to rapidly reach the dehydrogenation temperature, increasing the hydrogen release rate.

[0008] The aforementioned patents have achieved some results in exploring suitable hydrogen storage materials. However, the hydrogen storage materials provided by CN104555914A and CN109704274A have high volatility, which is not conducive to long-term storage. Moreover, the hydrogen storage material described in the former has a low hydrogen storage capacity; the hydrogen storage material described in the latter has a high dehydrogenation temperature of the hydrogenation product and low hydrogen storage efficiency; the hydrogen storage material provided by CN109353987A has a slow dehydrogenation rate, which is not conducive to industrial applications.

[0009] The current technical challenge lies in the fact that some LOHCs with high hydrogen storage capacity are solids or high-viscosity liquids at room temperature, such as N-ethylcarbazole, which are not conducive to large-scale applications. The conventional approach is to add low-melting-point organic liquids to form solutions or control incomplete dehydrogenation to lower the melting point, but this also reduces the hydrogen storage capacity of the material.

[0010] The catalytic dehydrogenation process of LOHCs involves a high enthalpy change, requiring a large amount of heat and a high temperature, typically above 300 °C. Therefore, the energy consumed in LOHC dehydrogenation cannot be supplied by the waste heat from fuel cells, which reduces the energy utilization efficiency of hydrogen-carrying LOHCs.

[0011] Therefore, it is indeed necessary to provide an improved hydrogen storage system to overcome the problems existing in current hydrogen storage methods. Utility Model Content

[0012] This invention provides a liquid hydrogen storage system, which includes an integrated hydrogen storage device and a hydrogen storage medium. The integrated hydrogen storage device includes a liquid storage tank for storing the hydrogen storage medium, a gas storage tank for storing hydrogen, a reactor connected to the output end of the liquid storage tank and the gas storage tank, a condenser connected to the reactor, a gas-liquid separator connected to the output end of the condenser, a gas compressor, and a gas buffer tank. The hydrogen storage medium is selected from one or more unsaturated aromatic hydrocarbons or heterocyclic unsaturated compounds with a boiling point of less than 100°C, a saturated vapor pressure of greater than 1 kPa, and a saturation temperature of 20°C.

[0013] Furthermore, a sampling port is provided at the bottom of the storage tank to facilitate real-time sampling for controlling the reaction progress. The storage tank and the reactor are connected by a first infusion pipe and a second infusion pipe. The second infusion pipe has a liquid flow meter and a second infusion valve for conveying the hydrogen storage medium in the storage tank to the reactor. The reactor is connected to the storage tank at the bottom by a first infusion pipe. The first infusion pipe is equipped with an infusion valve and an infusion pump for returning the partially reacted liquid in the lower part of the reactor to the storage tank.

[0014] Furthermore, the gas storage tank is used to store hydrogen. The gas storage tank is connected to the bottom of the reactor through a first gas supply pipe. The first gas supply pipe is equipped with a pressure reducing valve and a gas flow meter for inputting the gas from the gas storage tank into the reactor.

[0015] Furthermore, the reactor contains a catalyst layer and a heater from top to bottom.

[0016] Furthermore, a condenser is installed above the reactor to condense and liquefy the hydrogen storage medium gas. The other end of the condenser is connected to a gas-liquid separator. The gas-liquid separator is equipped with a third gas supply pipe connected to a gas compressor and a third liquid supply pipe connected to the reactor. The condensed liquid hydrogen storage medium re-enters the reactor through the third liquid supply pipe. The hydrogen separated by the gas-liquid separator is discharged through a vent valve or enters a gas buffer tank through a gas compressor. The gas buffer tank is connected to the reactor and the gas storage tank through a second gas supply pipe and a fourth gas supply pipe, respectively. The hydrogen can either be fed into the reactor to continue participating in the reaction or stored in the gas storage tank. The gas buffer tank is connected to the reactor, and the connection has a gas supply valve. The second gas supply pipe has a gas supply valve, and the fourth gas supply pipe has a gas pressure reducing valve.

[0017] Furthermore, the heteroatoms in the heterocyclic unsaturated compound are one or more of N, S, O and P, and the total number of heterocycles and aromatic rings is 1 to 20, and the total number of heteroatoms is 1 to 20.

[0018] Furthermore, the hydrogen storage medium is selected from one or more of propionaldehyde, acetone, isobutyraldehyde, acrylonitrile, butyraldehyde, benzene, and cyclohexene.

[0019] Furthermore, the hydrogen storage medium is acetone.

[0020] Furthermore, the catalyst is one or more of Cu, Zn, Pt, Pd, Ni, Ru, and Rh, and the support is one or more of Al2O3, activated carbon, zeolite, and carbon nanotubes.

[0021] Furthermore, the catalyst is Cu-Ni(Al2O3).

[0022] The beneficial effects of this invention are as follows: By selecting a hydrogen storage liquid with a low melting and boiling point, the hydrogen storage material remains liquid over a wide temperature range, which is beneficial for its large-scale application. Furthermore, the dehydrogenation and hydrogenation temperatures are low, which helps reduce energy consumption. The dehydrogenation and hydrogenation are carried out under gaseous conditions, resulting in a faster reaction rate. In this invention's liquid hydrogen storage system, the hydrogenation products, after heating, form a gaseous storage medium and a hydrogen mixture, which sequentially pass through a condenser, a gas-liquid separator, a gas compressor, and a gas buffer tank. This achieves a hydrogen pressurization, cooling, and reflux process, effectively recovering the liquid hydrogen storage material and ensuring the purity of the hydrogen.

[0023] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit the present invention. Attached Figure Description

[0024] The accompanying drawings, which form part of this application, are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention.

[0025] Figure 1 This is a schematic diagram of one embodiment of the integrated hydrogenation device of this utility model.

[0026] The attached diagram is labeled as follows: 1. Liquid storage tank; 11. Sampling port; 12. Second infusion valve; 13. Liquid flow meter; 2. Gas storage tank; 21. Gas pressure reducing valve 1; 22. Gas flow meter; 3. Reactor; 31. Catalyst layer; 32. Heater; 33. Manhole; 34. First infusion valve; 35. Infusion pump; 4. Condenser; 5. Gas-liquid separator; 51. Exhaust valve; 6. Gas compressor; 7. Gas buffer tank; 71. Gas pressure reducing valve; 72. Gas infusion valve. Detailed Implementation

[0027] Figure 1 The present invention discloses an integrated liquid hydrogen storage system, which includes an integrated hydrogen storage device and a hydrogen storage medium. The integrated hydrogen storage device includes a liquid storage tank 1 for storing the hydrogen storage medium, a gas storage tank 2 for storing hydrogen, a reactor 3 connected to the output end of the liquid storage tank 1 and the gas storage tank 2, a condenser 4 connected to the reactor 3, a gas-liquid separator 5 connected to the output end of the condenser 4, a gas compressor 6, and a gas buffer tank 7.

[0028] A sampling port 11 is provided at the bottom of the storage tank 1 for real-time sampling to control the reaction progress. The storage tank 1 is connected to the reactor 3 via a first delivery pipe and a second delivery pipe. The second delivery pipe has a liquid flow meter 13 and a second delivery valve 12 for delivering the hydrogen storage medium from the storage tank 1 to the reactor 3. The reactor 3 is connected to the storage tank 1 at the bottom via a first delivery pipe. The first delivery pipe has a delivery valve 34 and a delivery pump 35 for returning the partially reacted liquid in the lower part of the reactor 3 to the storage tank 1. The gas storage tank 2 is used to store hydrogen. The gas storage tank 2 is connected to the bottom of the reactor 3 via a first gas delivery pipe. The first gas delivery pipe has a pressure reducing valve 21 and a gas flow meter 22 for inputting the gas from the gas storage tank 2 into the reactor 3. The reactor 3 contains a catalyst layer 31 and a heater 32 from top to bottom. A manhole 33 is provided on the wall of the reactor 3 for maintenance. A condenser 4 is provided at the top of the reactor 3 for condensing and liquefying the hydrogen storage medium gas. The other end of the condenser 4 is connected to the gas-liquid separator 5. The gas-liquid separator 5 is equipped with a third gas supply pipe connected to the gas compressor 6 and a third liquid supply pipe connected to the reactor 3. The condensed liquid hydrogen storage medium re-enters the reactor 3 through the third liquid supply pipe. The hydrogen separated by the gas-liquid separator 5 is discharged through the vent valve 51 or enters the gas buffer tank 7 through the gas compressor 6. The gas buffer tank 7 is connected to the reactor 3 and the gas storage tank 2 through the second gas supply pipe and the fourth gas supply pipe, respectively. The hydrogen can either be fed into the reactor 3 to continue participating in the reaction or stored in the gas storage tank 2. The gas buffer tank is connected to the reactor, and the connection has a gas supply valve 71. The second gas supply pipe has a gas supply valve, and the fourth gas supply pipe has a gas pressure reducing valve 72.

[0029] The hydrogen storage medium is selected from one or more unsaturated aromatic hydrocarbons or heterocyclic unsaturated compounds with a boiling point less than 100°C, a saturated vapor pressure greater than 1 kPa, and a saturated vapor pressure of 20°C. The heteroatoms in the heterocyclic unsaturated compounds are one or more of N, S, O, and P. The total number of heterocycles and aromatic rings in the heterocyclic unsaturated compounds is 1 to 20, and the total number of heteroatoms is 1 to 20. The hydrogen storage medium is selected from one or more of propionaldehyde, acetone, isobutyraldehyde, acrylonitrile, butyraldehyde, benzene, and cyclohexene. The hydrogen storage medium is acetone.

[0030] The catalyst is one or more of Cu, Zn, Pt, Pd, Ni, Ru, and Rh, and the support is one or more of Al2O3, activated carbon, zeolite, and carbon nanotubes. The catalyst is Cu-Ni(Al2O3).

[0031] The integrated hydrogen storage device provided by this utility model is used as follows:

[0032] Hydrogenation process:

[0033] Step 1: The hydrogen storage medium in the storage tank 1 is introduced into the reactor 3 through the second liquid delivery pipe and heated to the hydrogenation temperature; since the hydrogen storage medium selected in this device has a high saturated vapor pressure, it can be quickly converted into the gas phase.

[0034] Step 2: Hydrogen gas is introduced into reactor 3. Under the action of a catalyst, the gaseous storage medium rapidly undergoes an addition reaction with the hydrogen gas to generate hydrogenated products.

[0035] Step 3: The hydrogenated liquid product is discharged through the drain port at the bottom of reactor 3 and transported to storage tank 1 through the delivery pipe.

[0036] Step 4: The gas above reactor 3 is discharged through the gas outlet and separated into hydrogen gas and liquid hydrogen storage medium after passing through the condenser. The hydrogen storage medium is returned to reactor 3 to continue the reaction, and the hydrogen gas is fed into reactor 3 as circulating hydrogen through the compressor to continue the reaction.

[0037] The reaction progress can be controlled by detecting the content of hydrogenation products in storage tank 1.

[0038] Dehydrogenation process:

[0039] Step 1: The hydrogen storage medium in storage tank 1 is introduced into reactor 3 through the delivery pipe and heated to the dehydrogenation temperature; since the hydrogen storage medium selected in this device has a high saturated vapor pressure, it can be quickly converted into the gas phase.

[0040] Step 2: The gaseous storage medium undergoes a rapid dehydrogenation reaction under the action of a catalyst, generating dehydrogenation products and hydrogen gas.

[0041] Step 3: The dehydrogenated liquid product is discharged through the drain port at the bottom of reactor 3 and transported to storage tank 1 through the delivery pipe.

[0042] Step 4: The gas above reactor 3 passes through condenser 4 and gas-liquid separator 5 to separate hydrogen gas and liquid hydrogen storage medium; the hydrogen storage medium flows back into reactor 3 to continue the reaction, and the hydrogen is discharged to storage tank 2 through gas pipeline.

[0043] The reaction progress can be controlled by detecting the content of hydrogenation products in storage tank 1.

[0044] This invention utilizes a hydrogen storage liquid with a low melting and boiling point, allowing the hydrogen storage material to remain liquid at room temperature and even over a wide temperature range, which is beneficial for large-scale application. Furthermore, the dehydrogenation and hydrogenation temperatures are relatively low, reducing energy consumption. The dehydrogenation and hydrogenation occur in the gas phase, resulting in a faster reaction rate. In this invention's liquid hydrogen storage system, the hydrogenation products, after heating, form a gaseous storage medium and a hydrogen mixture, which sequentially pass through a condenser 4, a gas-liquid separator 5, a gas compressor, and a gas buffer tank 7. This process achieves hydrogen pressurization, cooling, and reflux, effectively recovering the liquid hydrogen storage material and ensuring the purity of the hydrogen.

[0045] 300g of hydrogen storage medium was added to the integrated hydrogen storage device as the hydrogen storage medium. The hydrogen storage performance of different hydrogen storage media was tested under different temperatures and catalyst conditions. The catalyst addition amount was 1g, and the hydrogenation and dehydrogenation time was 5h. In this invention, "hydrogenation amount" and "dehydrogenation amount" refer to the weight percentage of hydrogen relative to the total mass of the original hydrogen storage system. The experimental results are shown in the table below.

[0046] Table 1 Hydrogen storage performance of different hydrogen storage media

[0047] The above description is merely a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any changes or substitutions conceived without inventive effort should be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the scope defined in the claims.

Claims

1. A liquid hydrogen storage system, characterized in that, It includes an integrated hydrogen storage device and a hydrogen storage medium. The integrated hydrogen storage device includes a liquid storage tank (1) for storing the hydrogen storage medium, a gas storage tank (2) for storing hydrogen, a reactor (3) connected to the output end of the liquid storage tank (1) and the gas storage tank (2), a condenser (4) connected to the reactor (3), a gas-liquid separator (5) connected to the output end of the condenser (4), a gas compressor (6), and a gas buffer tank (7). The hydrogen storage medium is selected from one or more unsaturated aromatic hydrocarbons or heterocyclic unsaturated compounds with a boiling point of less than 100°C, a saturated vapor pressure of greater than 1 kPa, and a temperature of 20°C.

2. The liquid hydrogen storage system according to claim 1, characterized in that, A sampling port (11) is provided below the storage tank (1) to facilitate real-time sampling to control the reaction progress. The storage tank (1) and the reactor (3) are connected by a first infusion pipe and a second infusion pipe. The second infusion pipe has a liquid flow meter (13) and a second infusion valve (12) for conveying the hydrogen storage medium in the storage tank (1) to the reactor (3). The reactor (3) is connected to the storage tank (1) below by a first infusion pipe. The first infusion pipe is equipped with an infusion valve and an infusion pump (35) for conveying the partially reacted liquid in the lower part of the reactor (3) back to the storage tank (1).

3. The liquid hydrogen storage system according to claim 1, characterized in that, The gas storage tank (2) is used to store hydrogen. The gas storage tank (2) is connected to the bottom of the reactor (3) through the first gas supply pipe. The first gas supply pipe is equipped with a pressure reducing valve and a gas flow meter (22) for inputting the gas from the gas storage tank (2) into the reactor (3).

4. The liquid hydrogen storage system according to claim 1, characterized in that, The reactor (3) is provided with a catalyst layer (31) and a heater (32) from top to bottom.

5. The liquid hydrogen storage system according to claim 1, characterized in that, A condenser (4) is provided above the reactor (3) for condensing and liquefying the hydrogen storage medium gas. The other end of the condenser (4) is connected to the gas-liquid separator (5). The gas-liquid separator (5) is provided with a third gas supply pipe connected to the gas compressor (6) and a third liquid supply pipe connected to the reactor (3). The condensed liquid hydrogen storage medium re-enters the reactor (3) through the third liquid supply pipe. The hydrogen separated by the gas-liquid separator (5) is discharged through the vent valve (51) or enters the gas buffer tank (7) through the gas compressor (6). The gas buffer tank (7) is connected to the reactor (3) and the gas storage tank (2) through the second gas supply pipe and the fourth gas supply pipe, respectively. The gas buffer tank (7) is connected to the reactor (3) and has a gas supply valve (72) on the connection. The second gas supply pipe has a gas supply valve (72) and the fourth gas supply pipe has a gas pressure reducing valve (71).

6. The liquid hydrogen storage system according to claim 1, characterized in that, The heteroatoms in the heterocyclic unsaturated compound are one or more of N, S, O and P, and the total number of heterocycles and aromatic rings is 1 to 20, and the total number of heteroatoms is 1 to 20.

7. The liquid hydrogen storage system according to claim 6, characterized in that, The hydrogen storage medium is selected from one or more of propionaldehyde, acetone, isobutyraldehyde, acrylonitrile, butyraldehyde, benzene, and cyclohexene.

8. The liquid hydrogen storage system according to claim 7, characterized in that, The hydrogen storage medium is acetone.

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