Low resistance low temperature conversion coil protected liquid hydrogen storage tank

Abstract

This invention relates to a liquid hydrogen storage tank protected by a low-resistance, low-temperature conversion coil, comprising a hydrogen storage inner liner, an insulated outer liner surrounding the inner liner, a conversion coil disposed between the inner and outer liners, and catalyst packing sections spaced apart within the conversion coil; wherein the conversion coil is used to draw out hydrogen gas from the inner liner; and along the hydrogen flow direction, the spacing between adjacent catalyst packing sections gradually decreases. Compared with the prior art, this invention uses a spaced-apart catalyst arrangement to reduce the impact of catalyst bed resistance, further fully utilize the cold energy from the conversion of secondary positive hydrogen, and improve the thermal insulation effect of the liquid hydrogen storage tank.

Description

Technical Field

[0001] This invention belongs to the field of liquid hydrogen storage technology and relates to a liquid hydrogen storage tank with low resistance and low temperature conversion coil protection. Background Technology

[0002] Liquid hydrogen has become an important mode of hydrogen storage and transportation due to its high energy density per unit volume. However, due to the heat leakage problem of hydrogen storage devices during the storage and transportation process, liquid hydrogen will inevitably evaporate due to heat leakage. Therefore, reducing liquid hydrogen evaporation is one of the urgent problems to be solved in the current liquid hydrogen storage and transportation.

[0003] Hydrogen is a diatomic molecule, with two hydrogen nuclei spinning around an axis. Based on the relative directions of their spins, hydrogen molecules can be divided into higher-energy orthogonal hydrogen and lower-energy secondary hydrogen. Ordinary hydrogen is a mixture of these two forms, and the equilibrium concentrations of orthogonal and secondary hydrogen are only temperature-dependent. At temperatures above room temperature, it contains 75% orthogonal hydrogen and 25% secondary hydrogen. When the temperature decreases, orthogonal hydrogen spontaneously converts to secondary hydrogen, releasing heat. Due to the slow conversion process, catalysts are often used in liquid hydrogen production to accelerate this conversion, ensuring that the secondary hydrogen content in the liquid hydrogen product reaches 95%. Conversely, when the temperature increases, secondary hydrogen absorbs heat and converts back to orthogonal hydrogen. Therefore, during the storage and transportation of liquid hydrogen, the conversion of secondary hydrogen to orthogonal hydrogen can be utilized to absorb heat leakage from the storage and transportation equipment, achieving long-term insulation of the equipment. Simultaneously, the hydrogen gas volatilized from the storage tank has an extremely low temperature and requires only a small amount of cooling to liquefy again, further reducing evaporation losses.

[0004] Invention patent CN 103836334 A discloses a device for continuous conversion of secondary hydrogen and utilization of cold energy. It mainly includes an outer container of a liquid hydrogen storage tank, an inner container of the liquid hydrogen storage tank, an insulation layer, a hydrogen outlet pipe, a hydrogen vent pipe, a coil, and a catalyst placed inside the coil. Secondary hydrogen obtained from the evaporation of liquid hydrogen is introduced into the coil containing the catalyst to absorb ambient heat leakage. However, for practical applications, although the catalyst can improve conversion efficiency, improper filling can increase bed resistance, hindering the flow of hydrogen within the coil and resulting in incomplete utilization of the cold energy from the secondary hydrogen conversion. Furthermore, when hydrogen flows out of the inner container of the liquid hydrogen storage tank, its temperature is low. As the hydrogen flows through the coil and continuously absorbs heat leakage, its temperature increases. Since the equilibrium concentrations of secondary and primary hydrogens are only temperature-dependent, even if the secondary and primary hydrogens are completely converted through the catalyst immediately after the hydrogen flows out of the inner container, the conversion cold energy is still very low. Therefore, the utilization rate of some catalysts is low, meaning that only a small amount of catalyst is needed to achieve optimal results. In the later stages of the coil, as the temperature continuously rises, it is necessary to increase the amount of catalyst to achieve efficient utilization of cooling capacity. Currently, most of the catalysts for the n- and para-n-hydrogen conversion in China are imported, which have long delivery cycles and high prices. Therefore, reasonable arrangement of the catalysts is beneficial to saving production costs. Summary of the Invention

[0005] The purpose of this invention is to provide a liquid hydrogen storage tank with low-resistance, low-temperature conversion coil protection. By rationally arranging the catalyst along the hydrogen flow direction, the catalyst bed resistance is reduced, fully utilizing the cold energy from the conversion of secondary hydrogen to positive hydrogen. Simultaneously, a throttling expansion device can be coupled in place to further maximize the utilization of the hydrogen's cold energy.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A liquid hydrogen storage tank with low resistance and low temperature conversion coil protection includes a hydrogen storage inner liner, an insulated outer liner sleeved outside the hydrogen storage inner liner, a conversion coil disposed between the hydrogen storage inner liner and the insulated outer liner, and a catalyst filling section spaced within the conversion coil.

[0008] The aforementioned conversion coil is used to draw out hydrogen from the hydrogen storage liner; and along the direction of hydrogen flow, the spacing between adjacent catalyst filling sections gradually decreases.

[0009] Furthermore, the catalyst filling section includes a catalyst filled in the conversion coil and catalyst filters disposed at both ends of the catalyst.

[0010] Furthermore, the catalyst is one or more of the following: porous columnar catalyst, porous block catalyst, or porous spherical catalyst.

[0011] Furthermore, the conversion coil is in contact with the inner surface of the insulated outer liner.

[0012] Furthermore, the conversion coil is arranged in a spiral shape.

[0013] Furthermore, multiple insulated outer liner are sequentially fitted around the hydrogen storage inner liner; conversion coils are interconnected between the innermost insulated outer liner and the hydrogen storage inner liner, as well as between adjacent insulated outer liners.

[0014] Furthermore, the innermost insulating outer liner and the hydrogen storage inner liner are in a vacuum state, or are filled with heat-insulating material.

[0015] Furthermore, the space between adjacent insulated outer liner is either in a vacuum state or filled with thermal insulation material.

[0016] Furthermore, two heat-insulating outer liner are sequentially fitted around the hydrogen storage inner liner.

[0017] Furthermore, it also includes a condenser tube installed inside the hydrogen storage liner and a throttling expansion device installed at the inlet of the condenser tube.

[0018] Compared with the prior art, the present invention has the following characteristics:

[0019] 1) This invention utilizes the cooling energy from the conversion of secondary hydrogen to positive hydrogen by setting up a conversion coil, thereby balancing the heat leakage of the liquid hydrogen storage tank and facilitating the storage of liquid hydrogen.

[0020] 2) The high-pressure hydrogen in the hydrogen storage tank releases a large amount of cold energy through the throttling expansion device, causing part of the high-pressure hydrogen to be converted into low-pressure, low-temperature hydrogen, and another part to be directly liquefied into low-temperature liquid hydrogen. This part of the low-temperature liquid hydrogen is liquefied again in the condenser tube through cold energy exchange, reducing the overall evaporation of liquid hydrogen in the hydrogen storage tank. At the same time, since the high-pressure hydrogen is converted into low-pressure hydrogen after throttling expansion, the low-pressure hydrogen flows slowly or even is blocked in the conversion coil filled with a large amount of catalyst, which is not conducive to the flow and conversion of hydrogen in the conversion coil. Therefore, this invention reduces the layer resistance caused by the catalyst bed by setting the catalyst at intervals according to the airflow direction, so that the low-pressure hydrogen after throttling expansion flows more smoothly in the conversion coil, while saving the amount of catalyst used and saving costs.

[0021] 3) The present invention provides catalyst filters at both ends of the catalyst filling section, which can prevent the catalyst from being discharged from the conversion coil with the airflow. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of a liquid hydrogen storage tank with low-resistance cryogenic conversion coil protection in Example 1;

[0023] Figure 2 This is a schematic diagram of the liquid hydrogen storage tank with a throttling expansion device in Example 2;

[0024] Figure 3 This is a schematic diagram of the catalyst-filled section.

[0025] Figure 4 This is a schematic diagram of the catalyst packing section distribution structure within the conversion coil;

[0026] Figure 5 Schematic diagram of the catalyst structure; Left: porous columnar; Middle: porous blocky; Right: porous spherical;

[0027] Explanation of markings in the diagram:

[0028] 1-Hydrogen storage inner liner, 2-Insulated outer liner, 3-Conversion coil, 4-Catalyst, 5-Catalyst filter, 6-Condenser, 7-Throttling expansion device. Detailed Implementation

[0029] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0030] Example 1:

[0031] like Figure 1 The liquid hydrogen storage tank shown is protected by a low-resistance cryogenic conversion coil. It includes a hydrogen storage inner liner 1, an insulated outer liner 2 fitted over the inner liner 1, and a conversion coil 3 located between the inner liner 1 and the outer liner 2, with multiple catalyst-filled sections spaced apart internally. One end of the conversion coil 3 is connected to the inner liner 1, and the other end is connected to the outer liner 2. It is used to draw out the hydrogen (mainly secondary hydrogen) evaporated from the inner liner 1 and convert it through a catalyst.

[0032] Specifically, such as Figure 2 As shown, the catalyst filling section includes catalyst 4 filled inside the conversion coil 3, and catalyst filters 5 located at both ends of catalyst 4. Catalyst 4 can be one or more of the following: carbon, chromium oxide, iron oxide, iron-aluminum oxide, iron hydroxide, chromium hydroxide, etc. Catalyst filters 5 prevent the gas from carrying catalyst 4 out of the conversion coil 3 during flow, thus protecting catalyst 4.

[0033] Preferably, a plurality of insulated outer liner 2 are sequentially fitted outside the hydrogen storage inner liner 1; a conversion coil 3 is provided between the innermost insulated outer liner 2 and the hydrogen storage inner liner 1, as well as between adjacent insulated outer liner 2. In this embodiment, two insulated outer liner 2 are sequentially fitted outside the insulated outer liner 2, and the conversion coil 3 spirally passes through the interlayer between the hydrogen storage inner liner 1 and the middle insulated outer liner 2, and the interlayer between the middle insulated outer liner 2 and the outer insulated outer liner 2.

[0034] Since ambient heat is gradually transferred to the interior through the outer liner, the conversion coil 3 is wound around the inner surface of each layer of insulated outer liner 2, allowing the leaked heat to be quickly absorbed and converted. By using two insulated outer liner 2, good thermal insulation is achieved while maintaining the volume of the hydrogen storage device. By setting up the conversion coil 3, the cooling energy from the conversion of secondary hydrogen to positive hydrogen is utilized to balance the heat leakage of the liquid hydrogen storage tank, which is beneficial for the storage of liquid hydrogen.

[0035] In some preferred embodiments, the space between the hydrogen storage inner liner 1 and the intermediate insulating outer liner 2 is either a vacuum or filled with thermal insulation material. Correspondingly, the space between the intermediate insulating outer liner 2 and the outer insulating outer liner 2 is either a vacuum or filled with thermal insulation material. The thermal insulation material includes one or more of the following: thermal insulation cotton, diene elastomer foamed flexible insulation material, porous polyurethane foam board, etc.

[0036] Meanwhile, due to the resistance of the catalyst bed, the gas flow in the conversion coil 3 can be slow or even stagnant. Therefore, to ensure smoother hydrogen flow in the conversion coil 3, it is necessary to reduce the bed resistance of the catalyst 4 within the conversion coil 3, thereby increasing the conversion efficiency from secondary hydrogen to positive hydrogen. Thus, this embodiment employs a method of spaced-out arrangement of the catalyst 4, such as... Figure 3As shown, this can greatly reduce the impact of bed resistance, which is beneficial to the flow of hydrogen in the conversion coil 3.

[0037] Furthermore, this embodiment continuously reduces the spacing between catalysts 4 according to the airflow direction, which is beneficial for fully and rationally utilizing the cooling energy of the conversion and improving the utilization rate of catalysts 4. Therefore, the above-mentioned method of setting the catalyst spacing in a throttling expansion coupling configuration results in better thermal insulation of the liquid hydrogen storage tank.

[0038] Meanwhile, due to the relatively long length of the conversion coil 3, when the liquid hydrogen in the liquid hydrogen storage tank evaporates rapidly, the hydrogen flux within the conversion coil 3 is high. In this situation, if fine particulate catalysts are used, the bed resistance is high, hindering hydrogen flow and affecting the conversion efficiency. If large, blocky particles with a smaller specific surface area are used, although bed resistance can be reduced, the high hydrogen flow rate decreases the contact area and contact time between hydrogen and the catalyst, which is also detrimental to conversion. Therefore, if… Figure 4 As shown, catalyst 4 is configured as one or more of porous columnar, porous block or porous spherical shapes. This can further reduce bed resistance and increase the contact area with hydrogen, thereby increasing the effective active area of ​​catalyst 4, which is beneficial to the conversion of secondary hydrogen to positive hydrogen.

[0039] Example 2:

[0040] like Figure 2 As shown, based on the liquid hydrogen storage tank described in Example 1, a condenser 6 and a throttling expansion device 7 located at the inlet of the condenser 6 are provided in the inner liner of the hydrogen storage tank. The throttling expansion device 7 is preferably a throttling expansion valve. That is, the high-pressure hydrogen gas evaporated in the inner liner 1 flows into the condenser 6 and the conversion coil 3 through the throttling expansion valve, and after being converted by the catalyst 4, it is finally discharged outside the liquid hydrogen storage tank.

[0041] Because the hydrogen gas evaporated from the hydrogen storage liner 1 has the characteristics of high pressure and low temperature, when it flows through the throttling expansion device 7, it releases cold energy instantly through the throttling expansion effect, turning the high-pressure low-temperature hydrogen gas into liquid hydrogen and even lower-temperature low-pressure hydrogen gas, which then flows into the condenser tube 6. At this time, the temperature of the liquid hydrogen and hydrogen gas in the condenser tube 6 is lower than that of the hydrogen gas in the hydrogen storage liner 1, so the low-temperature hydrogen gas around the outer wall of the condenser tube 6 can be liquefied through cold energy exchange.

[0042] To ensure more efficient heat exchange, in a preferred embodiment, the condenser tube 6 is configured as a spiral coil.

[0043] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A liquid hydrogen storage tank protected by a low-resistance cryogenic conversion coil, characterized in that, It includes a hydrogen storage inner liner (1), an insulated outer liner (2) fitted outside the hydrogen storage inner liner (1), a conversion coil (3) located between the hydrogen storage inner liner (1) and the insulated outer liner (2), and a catalyst filling section spaced within the conversion coil (3); The conversion coil (3) is used to draw out hydrogen from the hydrogen storage liner (1); and along the direction of hydrogen flow, the spacing between adjacent catalyst filling sections gradually decreases; The catalyst filling section includes a catalyst (4) filled in the conversion coil (3) and catalyst filters (5) disposed at both ends of the catalyst (4); The catalyst (4) is one or more of the following: porous columnar catalyst, porous block catalyst, or porous spherical catalyst; The conversion coil (3) is in contact with the inner surface of the heat-insulating outer liner (2); The conversion coil (3) is arranged in a spiral shape; Multiple heat-insulating outer liner (2) are sequentially fitted around the hydrogen storage inner liner (1); conversion coils (3) are provided between the innermost heat-insulating outer liner (2) and the hydrogen storage inner liner (1), as well as between adjacent heat-insulating outer liner (2).

2. The liquid hydrogen storage tank with low-resistivity cryogenic conversion coil protection according to claim 1, characterized in that, The innermost heat-insulating outer liner (2) and the hydrogen storage inner liner (1) are in a vacuum state, or are filled with heat-insulating material.

3. The liquid hydrogen storage tank with low-resistivity cryogenic conversion coil protection according to claim 1, characterized in that, The adjacent heat-insulating outer shells (2) are in a vacuum state, or are filled with heat-insulating materials.

4. The liquid hydrogen storage tank with low-resistivity cryogenic conversion coil protection according to claim 1, characterized in that, Two heat-insulating outer liner (2) are sequentially fitted outside the hydrogen storage inner liner (1).

5. A liquid hydrogen storage tank with low-resistance cryogenic conversion coil protection according to claim 1, characterized in that, It also includes a condenser (6) installed inside the hydrogen storage liner (1) and a throttling expansion device (7) installed at the inlet of the condenser (6).

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