Liquid hydrogen storage tank

Abstract

This liquid hydrogen storage tank comprises a tank body, a dike, a pump, and a housing chamber. The tank body includes an inner tank for storing liquid hydrogen, and an outer tank formed with a cold insulation layer between the inner tank and the outer tank. The dike is erected so as to surround the outer periphery of the tank body. The pump discharges the liquid hydrogen in the inner tank to the outside through a side plate of the inner tank. The housing chamber houses the pump. The dike includes a ridge part protruding outward in the radial direction. The housing chamber is positioned between an outer peripheral surface of the ridge part and the side plate of the inner tank. A horizontal cross-section of the housing chamber is circular.

Description

Liquefied hydrogen storage tank

[0001] The present disclosure relates to a tank for storing liquefied hydrogen.

[0002] Liquefied gas storage tanks are known as storage facilities for low-temperature liquefied gases, such as liquefied hydrogen and liquefied natural gas. The tank includes a flat-bottomed tank body that stores the liquefied gas and a dike surrounding the tank body. The dike is constructed to prevent the stored liquefied gas from leaking out into the surrounding area in the event of damage to the tank body. Liquefied gas storage tanks are equipped with a pump for discharging the liquefied gas from the tank body (see, for example, Patent Document 1).

[0003] When the liquefied gas to be stored is liquefied hydrogen, it may be difficult to install the pump inside the inner tank of the tank body due to the difficulty of maintenance work, etc. In this case, a structure can be considered in which a pipe is installed that penetrates the tank body and the liquid barrier, and a pump storage chamber is installed inside the liquid barrier. The pipe is connected to the pump in the storage chamber, and the liquefied hydrogen stored in the tank body is dispensed through the pipe by operating the pump.

[0004] When the above tank structure is adopted, there is a possibility that liquefied hydrogen may leak from the inner tank into the pump chamber inside the dike due to some cause. The leaked liquefied hydrogen can be contained within the pump chamber, preventing it from diffusing into the atmosphere. However, measures must be taken to prevent the internal pressure of the pump chamber from increasing as the leaked liquefied hydrogen accumulates in the pump chamber.

[0005] Japanese Patent Application Laid-Open No. 2017-132619

[0006] An object of the present disclosure is to provide a liquefied hydrogen storage tank that can increase the resistance to an increase in internal pressure in a pump storage chamber provided inside a liquid barrier when liquefied hydrogen enters the pump storage chamber.

[0007] A liquefied hydrogen storage tank according to one aspect of the present disclosure comprises a tank body including an inner tank for storing liquefied hydrogen and an outer tank formed between the inner tank and the outer tank with an insulation layer interposed therebetween; a liquid barrier erected to surround the outer periphery of the tank body; a pump that discharges liquefied hydrogen in the inner tank to the outside through a side plate of the inner tank; and a storage chamber that houses the pump, wherein the liquid barrier includes a protrusion that protrudes radially outward, and the storage chamber is located between the outer peripheral surface of the protrusion and the side plate of the inner tank, and the horizontal cross section of the storage chamber is circular.

[0008] The liquefied hydrogen storage tank of the present disclosure can provide a liquefied hydrogen storage tank that can increase the resistance to an increase in internal pressure in a pump storage chamber provided inside a liquid containment dike when liquefied hydrogen enters the pump storage chamber.

[0009] Fig. 1 is a cross-sectional view showing a liquefied hydrogen storage tank according to an embodiment of the present disclosure. Fig. 2 is a cross-sectional view taken along line II-II in Fig. 1. Fig. 3A is a partial cross-sectional view showing a modified example of the protrusion portion of the liquid barrier dike. Fig. 3B is a partial cross-sectional view showing a modified example of the protrusion portion of the liquid barrier dike. Fig. 4 is a cross-sectional view showing a pump chamber having an inner member. Fig. 5 is a cross-sectional view showing a pump chamber having a heat insulating layer. Fig. 6 is a cross-sectional view showing a pump chamber having a dome-shaped bottom wall. Fig. 7 is a partial cross-sectional view showing a further modified example of the protrusion portion of the liquid barrier dike.

[0010] [Overall Tank Structure] An embodiment of a liquefied hydrogen storage tank according to the present disclosure will now be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view showing a liquefied hydrogen storage tank 1 according to an embodiment of the present disclosure, and FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1. The liquefied hydrogen storage tank 1 is a multi-shell tank that stores liquefied hydrogen LH. The liquefied hydrogen storage tank 1 includes a tank body 10 having a multi-shell structure, a liquid barrier 2 erected to surround the outer periphery of the tank body 10, a pump 3 that discharges liquefied hydrogen LH from the tank body 10 to the outside, and a chamber 51 for the pump 3 located within the structure of the liquid barrier 2. FIG. 1 illustrates a double-shell tank as an example of a multi-shell tank.

[0011] The tank body 10 is a flat-bottom tank having a storage space 10A for storing liquefied hydrogen LH, and includes an outer tank 11 erected on a tank foundation 21, an inner tank 12 enclosed within the outer tank 11, and a cold insulation layer 13 disposed between the outer tank 11 and the inner tank 12. The tank foundation 21 is a concrete layer that forms the foundation of the tank body 10 and the dike 2. The outer tank 11 and the inner tank 12 both have a circular shape when viewed from above and are arranged concentrically. The tank body 10 may also be a multi-shell tank provided with an intermediate tank between the outer tank 11 and the inner tank 12.

[0012] The outer tank 11 is a sealed body made of metal such as carbon steel or stainless steel, and includes an outer tank bottom plate 11B, outer tank side plates 11S, and an outer tank roof 11R. The outer tank bottom plate 11B is laid directly on the tank foundation 21 and has a disk-like shape. The outer tank side plate 11S is erected from the periphery of the outer tank bottom plate 11B and has a cylindrical shape. The outer tank roof 11R is attached to the upper end of the cylindrical outer tank side plate 11S so as to cover the upper opening of the outer tank side plate 11S and has a dome-like shape.

[0013] The inner tank 12 is a tank that forms the storage space 10A that actually stores the liquefied hydrogen LH. The inner tank 12 is a sealed body made of a metal such as stainless steel, and is surrounded by the outer tank 11 via a predetermined space that serves as the cold insulation layer 13. The inner tank 12 includes an inner tank bottom plate 12B, inner tank side plates 12S, and an inner tank roof 12R. The inner tank bottom plate 12B has a disk-like shape with a smaller diameter than the outer tank bottom plate 11B. The inner tank side plate 12S stands upright from the periphery of the inner tank bottom plate 12B and has a cylindrical shape. The inner tank roof 12R is attached to the upper end of the inner tank side plate 12S and has a dome-like shape. Liquefied hydrogen LH is stored inside the inner tank 12, and gas vaporized from the liquefied hydrogen LH accumulates in the upper layer of the inner tank 12.

[0014] The cold insulation layer 13 utilizes the gap between the outer tub 11 and the inner tub 12 as an insulating space to improve the cold insulation of the inner tub 12. The cold insulation layer 13 may contain powder insulation material or solid insulation material. For example, the gap between the outer tub roof 11R and the inner tub roof 12R is filled with powder insulation material such as granular perlite. The gap between the outer tub side plate 11S and the inner tub side plate 12S is filled with granular perlite and glass wool. The gap between the outer tub bottom plate 11B and the inner tub bottom plate 12B is filled with insulating blocks such as foam glass.

[0015] The cold insulation layer 13 is filled with hydrogen gas, helium gas, nitrogen gas, or the like, together with a cold insulation material such as granular perlite. The gas to be filled preferably has a boiling point equal to or lower than that of the stored liquefied hydrogen LH, and from this perspective, hydrogen gas or helium gas is preferable. For example, a communication pipe may be provided to communicate the internal space of the inner tank 12 with the space of the cold insulation layer 13, and the vaporized gas of the stored liquefied hydrogen LH may be introduced into the cold insulation layer 13.

[0016] The dike 2 prevents the stored liquefied hydrogen LH from leaking out to the surrounding area in the event of damage to the tank body 10. The dike 2 is a cylindrical concrete structure constructed on the tank foundation 21 and erected to surround the outer periphery of the tank body 10. It is desirable for the concrete structure to incorporate reinforcing materials such as steel bars and prestressed concrete (PC) steel. A PC structure is particularly desirable, as it allows for the construction of a dike 2 with excellent strength. The dike 2 of this embodiment has a structure that does not leave a separation distance between it and the outer periphery of the tank body 10, i.e., the dike 2 and the outer tank side panel 11S are integrated. In the event of damage to the tank body 10, the dike 2 acts as a barrier to prevent leakage of the liquefied hydrogen LH, and the liquefied hydrogen LH is retained in the space of the cold insulation layer 13. In other words, the space located inside the outer peripheral surface 2A of the dike 2 becomes a storage space for leaked liquefied hydrogen LH.

[0017] The dike 2 has an outer peripheral surface 2A exposed to the outside and an inner peripheral surface 2B in contact with the outer tank side plate 11S. The dike 2 is characterized by a circular portion 22 and a protruding portion 23. The circular portion 22 is a cylindrical dike that surrounds the entire outer periphery of the tank body 10. Figure 1 shows an example in which the height of the circular portion 22 is approximately the same as the height of the outer tank side plate 11S. The protruding portion 23 is a structural portion that extends vertically and is provided corresponding to the location where the pump 3 is installed. A portion of the circular portion 22 protrudes radially outward. As shown in Figure 2, the outer peripheral surface 2A of the dike 2 bulges radially outward at the location where the protruding portion 23 is formed.

[0018] The pump 3 is disposed on the side of the tank body 10 and inside the protrusion 23, and generates a pumping force to discharge the liquefied hydrogen LH in the inner tank 12 to the outside through the side plates of the tank body 10. In this embodiment, the side plates are the inner tank side plate 12S and the outer tank side plate 11S. An extraction pipe 31 and a discharge pipe 32 are connected to the pump 3.

[0019] The extraction pipe 31 is a straight pipe that penetrates the side plate of the tank body 10 and the side of the dike 2 and dispenses the liquefied hydrogen LH stored in the inner tank 12. The extraction pipe 31 is a conduit that penetrates from the outside of the tank body 10 through the outer tank side plate 11S, the cold insulation layer 13, and the inner tank side plate 12S to the storage space 10A of the inner tank 12. One end of the extraction pipe 31 faces the liquefied hydrogen LH stored in the inner tank 12, and the other end is connected to the inlet end of the pump 3. The dispensing pipe 32 is a conduit that extends upward inside the protruding portion 23, passes over the top surface 23T of the protruding portion 23, and reaches the outside of the liquefied hydrogen storage tank 1. One end of the dispensing pipe 32 is connected to the outlet end of the pump 3, and the other end is connected to the inlet end of equipment that uses liquefied hydrogen LH as fuel or a transport truck.

[0020] In this embodiment, the pump 3 for dispensing the liquefied hydrogen LH inside the tank body 10 is located outside the inner tank 12. This is because maintenance work is easier than if the pump 3 were installed in the storage space 10A where the liquefied hydrogen LH is stored. In this case, space for installing the pump 3 is required on the side of the tank body 10. In this embodiment, the above-mentioned protrusion 23 is formed on the liquid barrier dyke 2, and a storage chamber 51 is provided inside it, thereby ensuring a place to install the pump 3.

[0021] The storage chamber 51 is disposed within the body of the protrusion portion 23, and has a spatial volume large enough to accommodate the pump 3 and a portion of the extraction pipe 31 and the discharge pipe 32. The storage chamber 51 is a cylindrical space extending in the vertical direction, and has a length that covers almost the entire vertical length of the liquid barrier dyke 2. In this embodiment, the storage chamber 51 has a shape with a circular horizontal cross section to ensure strength. The significance of making the storage chamber 51 circular in cross section will be described in detail below.

[0022] In this embodiment, the provision of the protrusions 23 causes the outer peripheral surface 2A of the liquid barrier 2 to form a portion that bulges outward in the radial direction, creating space for arranging the storage chamber 51. An outer wall 23A exists between the outer peripheral surface 2A and the storage chamber 51. An inner wall 23B exists between the storage chamber 51 and the tank body 10. The inner wall 23B is part of the annular portion 22 and is the body of the portion where the protrusions 23 exist.

[0023] An outlet opening 33 is provided in the inner wall portion 23B located radially inside the storage chamber 51, allowing the outlet pipe 31 to pass through into the storage chamber 51. The outlet opening 33 is a cylindrical hole that passes radially through the inner wall portion 23B near the lower end of the liquid barrier 2. A gap exists between the inner surface of the outlet opening 33 and the outer peripheral surface of the outlet pipe 31. Note that the outlet pipe 31 is joined where it passes through the outer tank side plate 11S. The pump 3 is disposed in the storage chamber 51 at a position opposite the outlet opening 33. The outlet pipe 31 may be an L-shaped pipe extending upward, and the pump 3 may be installed above the outlet opening 33.

[0024] The accommodation chamber 51 has an upper end opening 53 that opens to the top surface 23T of the protrusion portion 23. The upper portion of the accommodation chamber 51 also serves as a passageway 52. ​​The passageway 52 serves as a passageway when an operator accesses the pump 3 installed in the accommodation chamber 51 from the upper end opening 53. A ladder (not shown) is installed in the passageway 52 to allow the operator to move forward and backward. The upper end opening 53 is provided with an opening / closing door 54 that opens and closes the upper end opening 53. The opening / closing door 54 is normally closed and is opened during maintenance work, etc. The installation of the opening / closing door 54 can prevent rainwater, dust, and the like from entering the accommodation chamber 51 and the passageway 52, thereby keeping them clean.

[0025] The space of the storage chamber 51 is isolated from the cold insulation layer 13, and therefore can be an air environment. Therefore, workers can easily access the pump 3 near the bottom of the storage chamber 51 through the passage 52, facilitating maintenance work, etc. Note that in order to improve explosion-proof properties, the space of the storage chamber 51 may be filled with an inert gas such as nitrogen gas.

[0026] In the liquefied hydrogen storage tank 1 according to this embodiment, the inner space of the outer tank 11 and the storage chamber 51, which is the space within the body of the protrusion 23, form a liquid storage space that can store liquid that leaks from the inner tank 12. The upper surface of the liquid storage space is sealed by the outer tank roof 11R and the opening / closing door 56. Therefore, even if a liquid leak occurs due to damage to the tank body 10 or the like, the leaked liquid is contained in the liquid storage space, and the outflow of vaporized liquefied hydrogen LH can be suppressed.

[0027] Furthermore, a storage chamber 51 is provided in the protruding portion 23 of the dike 2, and the storage chamber 51 accommodates a pump 3 that discharges liquefied hydrogen LH to the outside through the tank side plate. This makes maintenance easier than when the pump is installed inside the inner tank 12. When the pump 3 is installed inside the inner tank 12 of a liquefied hydrogen storage tank 1 that stores liquefied hydrogen LH, the pump 3, which is immersed in the liquefied hydrogen LH, must be removed to the outside, making it difficult to develop a maintenance method that is safe and easy to operate. In contrast, in this embodiment, the pump 3 is disposed in the storage chamber 51 outside the inner tank side plate 12S, so the work of removing the pump 3 from the inner tank 12 itself does not occur, making maintenance easier.

[0028] [Details of the protrusion and storage chamber] In the liquefied hydrogen storage tank 1 having the above-described structure, leakage of liquefied hydrogen LH from the inner tank 12 to the storage chamber 51 in the dike 2 may occur due to some factor. For example, damage to the extraction pipe 31 may be one factor causing the leakage. The leaked liquefied hydrogen LH can be contained in the storage chamber 51 and prevented from diffusing into the atmosphere. However, it is expected that the internal pressure of the storage chamber 51 will increase as the leaked liquefied hydrogen LH accumulates in the storage chamber 51 and the volume increases due to vaporization of the liquefied hydrogen LH. The storage chamber 51 of this embodiment has a structure that is resistant to such an increase in internal pressure.

[0029] As shown in Figures 1 and 2, the protrusion 23 has approximately the same height as the outer tank side plate 11S and protrudes radially outward relative to the annular portion 22. The outer peripheral surface of the outer wall 23A of the protrusion 23 has a semicircular arc surface AR in the horizontal direction. The storage chamber 51 has a circular horizontal cross section. The center of the arc of the arc surface AR and the center of the circle of the storage chamber 51 approximately coincide with each other. While a "circular" horizontal cross section of the storage chamber 51 is most preferably a perfect circle, it may also be an ellipse or polygon that can be treated as a substantial circle, or a shape including irregular shapes such as slight straight lines or non-circular arcs.

[0030] Making the horizontal cross section of the storage chamber 51 circular has the following advantages. As noted at the bottom left of FIG. 2 , when the internal pressure of the storage chamber space R partitioned by the storage chamber 51 increases, a force F1 is generated from the radially inner side of the storage chamber space R toward the inner wall of the storage chamber 51. The force F1 is a force that tries to push the inner wall of the storage chamber 51 apart. If the horizontal cross section of the inner wall is circular, a balanced state can be formed to resist the circumferential stress F2 generated by the force F1. If the horizontal cross section of the storage chamber 51 were rectangular, stress concentration would occur at the corners, reducing the ability to resist the force F1. Therefore, the storage chamber 51 of this embodiment can withstand an increase in internal pressure, such as when liquefied hydrogen LH leaks.

[0031] In the event of a leak of the liquefied hydrogen LH, the liquefied hydrogen LH stored in the inner tank 12 flows into the storage chamber 51. The liquid level of the liquefied hydrogen LH in the storage chamber 51 is the same as the liquid level of the liquefied hydrogen LH in the tank body 10 and the cold insulation layer 13. Therefore, it is desirable that the horizontal cross section of the storage chamber 51 be circular up to the position of the liquid level of the liquefied hydrogen LH in the storage chamber 51, which is assumed when the inner tank 12 is full of liquefied hydrogen LH and the leakage occurs. Of course, the horizontal cross section may be circular over the entire vertical length of the storage chamber 51.

[0032] As long as the storage chamber 51 has a circular cross section, there are no limitations on the outer shape of the protrusion 23. Figures 3A and 3B show protrusions 231 and 232 according to modified examples. The protrusion 231 in Figure 3A has a rectangular horizontal cross section. The storage chamber 51, which has a circular horizontal cross section, is disposed inside the protrusion 231, which protrudes in a rectangular shape from the annular portion 22 of the liquid barrier 2. The protrusion 232 shown in Figure 3B has an arc surface AR that continues to the protrusion base from the annular portion 22, and has an outer shape that is approximately circular in horizontal cross section. The circular storage chamber 51 is disposed concentrically with the protrusion 232.

[0033] [Storage Chamber with Inner Member] In the above-described embodiment, it is desirable to provide an inner member on the wall surface that partitions the storage chamber 51 in the dike 2. Figure 4 is a cross-sectional view showing the storage chamber 51 of the pump 3 having the inner member 6. The shape of the protrusion 23 itself is the same as the protrusion 23 illustrated in Figure 2. The storage chamber 51 provided inside the protrusion 23 is provided with an inner member 6 as a lining. The inner member 6 may line the entire length of the storage chamber 51 in the vertical direction, or may extend up to a height equivalent to the liquid level of the liquefied hydrogen LH in the event of a leak.

[0034] The inner member 6 is desirably made of a material and thick enough to provide a reinforcing function for the storage chamber 51 and / or a barrier function for the liquefied hydrogen LH. The reinforcing function is to improve the strength of the wall of the storage chamber 51. The barrier function is to prevent hydrogen from leaking from the storage chamber 51 to the outside through the protrusions 23 when the liquefied hydrogen LH enters the storage chamber 51, and to prevent low-temperature embrittlement of the protrusions 23. The inner member 6 can be made of a metal material, a resin material, a ceramic material, or the like, as long as it provides the reinforcing function and / or barrier function. For example, low-temperature steel is one preferred material for the inner member 6. The inner member 6 may be made of a combination of multiple materials.

[0035] Regarding the combination of the protrusion portion 23 and the inner member 6, either of the following approaches can be adopted: (1) the protrusion portion 23 ensures strength against the internal pressure of the storage chamber 51, or (2) the inner member 6 ensures strength against the internal pressure of the storage chamber 51.

[0036] In the case of (1) above, the protrusions 23 may be made of prestressed concrete, which has excellent strength, and the inner member 6 may be made of a member that is resistant to low-temperature embrittlement (low-temperature resistance). For example, the inner member 6 may be made of low-temperature steel, which is thick enough to serve as a liner but is insufficient for strength reinforcement. In this case, the horizontal cross section of the inner wall itself that defines the storage chamber 51 is circular so that the inner wall generates circumferential stress. According to the above aspect (1), the strength of the protrusions 23 can be imparted by the prestressed concrete, and low-temperature embrittlement of the protrusions 23 can be suppressed even if liquefied hydrogen LH enters the storage chamber 51.

[0037] In the case of (2) above, the protrusions 23 may be made of reinforced concrete, and the inner member 6 may be a member that is resistant to low-temperature embrittlement (low-temperature resistance) and has the strength to withstand the internal pressure generated in the storage chamber 51. For example, low-temperature steel having a thickness sufficient to withstand the internal pressure alone may be used as the inner member 6. In this case, the inner surface of the inner member 6 forms the inner wall that defines the storage chamber 51, and therefore the horizontal cross section of the inner surface of the inner member 6 is circular. On the other hand, the horizontal cross section of the space within the protrusions 23 that houses the inner member 6 does not necessarily need to be circular. According to the above aspect (2), the inner member 6 can suppress low-temperature embrittlement of the protrusions 23 in the event of a leak of liquefied hydrogen LH, and the strength of the inner member 6 can also withstand the pressure of the leaked liquid. Therefore, the protrusions 23 can be made of reinforced concrete, which is relatively easy to construct. Alternatively, the protrusions 23 may be made of unreinforced concrete.

[0038] The inner member 6 may be a composite material that combines a metal material and a heat insulating material. Fig. 5 is a cross-sectional view showing a housing chamber 51 of the pump 3 having a heat insulating layer. In the example of Fig. 5, the pump 3 includes an outer liner 61, an inner liner 62, and a heat insulating layer 63 disposed between the liners 61 and 62, which correspond to the inner member 6 described above.

[0039] The outer liner 61 and the inner liner 62 can be made of a metal material such as steel, low-temperature steel, or aluminum alloy. The insulating layer 63 can be made of a foam material such as rigid urethane foam or insulating concrete. The insulating layer 63 may be formed as a space that can be evacuated and functions as a vacuum insulating layer during operation. Either the outer liner 61 or the inner liner 62 may be omitted. That is, it is sufficient to have a metal liner and an insulating layer 63 disposed inside or outside the liner. According to the embodiment of FIG. 5 , the liners 61 and 62 function as a barrier layer to prevent hydrogen leakage, while the insulating layer 63 can suppress heat transfer from the storage chamber 51 to the outer peripheral surface of the protrusion 23. Therefore, when liquefied hydrogen LH enters the storage chamber 51, low-temperature embrittlement of the concrete constituting the protrusion 23, frost formation on the outer peripheral surface of the protrusion 23 due to heat transfer from the cold of the liquefied hydrogen LH, the generation of liquefied air, and thermal stress in the protrusion 23 can be suppressed.

[0040] Other Embodiments Although the embodiments of the present disclosure have been described above, they are not limited to the above-described embodiments and various modifications are possible. For example, in the above-described embodiments, the storage chamber 51 has a circular horizontal cross section. However, the bottom wall of the storage chamber 51 may also be modified. FIG. 6 is a cross-sectional view showing a storage chamber 51 having a dome-shaped bottom wall 55. The bottom wall 55 has a downwardly convex hemispherical shape. A support base (not shown) for supporting the pump 3 is mounted on the bottom wall 55. According to the embodiment shown in FIG. 6, by making the bottom wall 55 of the storage chamber 51 dome-shaped, stress concentration areas are less likely to occur in the bottom wall 55 when the internal pressure of the storage chamber 51 increases.

[0041] In the above embodiment, an example has been shown in which the accommodation chamber 51 is disposed within the frame of the protrusion 23. The accommodation chamber 51 may be disposed between the outer wall 23A of the protrusion 23 and the inner tank side plate 12S. For example, the accommodation chamber 51 may be provided between the inner tank side plate 12S and the outer tank side plate 11S.

[0042] In the above embodiment, an example has been shown in which one protrusion 23 protrudes from the annular portion 22 of the dike 2. Alternatively, a plurality of protrusions 23 may be provided in the circumferential direction of the annular portion 22. Furthermore, in the above embodiment, an example has been shown in which one pump 3 is provided in one storage chamber 51. Alternatively, the volume of the storage chamber 51 may be increased, and a plurality of pumps 3 may be provided in the storage chamber 51.

[0043] The protrusion 23 may be provided in a manner spaced apart from the annular portion 22. Figure 7 shows a modified protrusion 233. The protrusion 233 includes a main body portion having a circular cross section and located at a position spaced apart from the annular portion 22 of the liquid barrier 2, and a connecting portion 24 connecting the main body portion to the annular portion 22. The width of the connecting portion 24 is set to be smaller than the outer diameter of the main body portion. The extraction opening 33 passes through the main body portion of the protrusion 233 from the annular portion 22, through the connecting portion 24, and reaches the storage chamber space R.

[0044] [Summary of the Disclosure] The specific embodiments described above include disclosures having the following configurations.

[0045] A liquefied hydrogen storage tank according to a first aspect of the present disclosure comprises a tank body including an inner tank for storing liquefied hydrogen and an outer tank formed between the inner tank and the outer tank with an insulation layer interposed therebetween; a liquid barrier erected to surround the outer periphery of the tank body; a pump that discharges liquefied hydrogen in the inner tank to the outside through a side plate of the inner tank; and a storage chamber that houses the pump, wherein the liquid barrier includes a protrusion that protrudes radially outward, and the storage chamber is located inside between the outer peripheral surface of the protrusion and the side plate of the inner tank, and the horizontal cross section of the storage chamber is circular.

[0046] According to the first aspect, the housing chamber that houses the pump has a shape with a circular horizontal cross section. When the horizontal cross section of the inner wall of the housing chamber is circular, a state of equilibrium can be formed and resistance can be achieved against the circumferential stress that occurs on the inner wall as the internal pressure of the housing chamber increases, making it possible to maintain the shape of the housing chamber. Therefore, even if liquefied hydrogen leaks from the inner tank into the housing chamber, the housing chamber can be made to be resistant to the liquid pressure. Note that a "circular" horizontal cross section includes not only a perfect circle but also an ellipse that can be treated as a substantial circle, and may include slight straight lines or non-circular arcs.

[0047] A liquefied hydrogen storage tank according to a second aspect is the liquefied hydrogen storage tank according to the first aspect, wherein the outer peripheral surface of the protrusion portion has an arcuate surface in the horizontal direction.

[0048] According to the second aspect, the outer peripheral surface of the protruding portion can be formed in a shape that corresponds to the shape of the accommodation chamber, which has a circular cross section.

[0049] A liquefied hydrogen storage tank according to a third aspect is the liquefied hydrogen storage tank according to the first or second aspect, wherein an inner member is provided on a wall surface that partitions the storage chamber.

[0050] According to the third aspect, the installation of the inner member can improve the strength of the wall surface of the storage chamber. Furthermore, the inner member can also function as a barrier layer that prevents hydrogen from leaking out of the storage chamber when liquefied hydrogen enters the storage chamber.

[0051] A liquefied hydrogen storage tank according to a fourth aspect is the liquefied hydrogen storage tank of the third aspect, wherein the protrusion portion is made of prestressed concrete, and the inner member is resistant to low temperatures.

[0052] According to the fourth aspect, the strength of the protrusions can be ensured by making the protrusions from prestressed concrete, and the low-temperature resistance of the inner member can suppress low-temperature deterioration of the protrusions even if they come into contact with liquefied hydrogen that has entered the storage chamber.

[0053] A liquefied hydrogen storage tank according to a fifth aspect is the liquefied hydrogen storage tank according to the third aspect, wherein the protrusion portion is made of concrete, and the inner member has resistance to low temperatures and strength sufficient to withstand the internal pressure generated in the storage chamber.

[0054] According to the fifth aspect, the inner member has low-temperature resistance and resistance to the internal pressure. This prevents the protrusions from becoming brittle at low temperatures, and the strength of the inner member can withstand the liquid pressure in the event of a leak of liquefied hydrogen. Therefore, the protrusions can be made of concrete, which is relatively easy to construct.

[0055] A liquefied hydrogen storage tank according to a sixth aspect is the liquefied hydrogen storage tank of the third aspect, wherein the inner member is made of a metal member and further comprises a heat insulating layer disposed on the inside or outside of the inner member.

[0056] According to the sixth aspect, the inner member serves as a barrier layer to prevent hydrogen leakage, while the insulating layer suppresses heat transfer from the storage chamber to the outer peripheral surface of the protrusions. Therefore, when liquefied hydrogen enters the storage chamber, it is possible to suppress the formation of frost on the outer peripheral surface of the protrusions and the generation of liquefied air due to heat transfer from the cold of the liquefied hydrogen.

[0057] A liquefied hydrogen storage tank according to a seventh aspect is the liquefied hydrogen storage tank according to any one of the first to sixth aspects, wherein the storage chamber includes a bottom wall having a downwardly convex dome shape.

[0058] According to the seventh aspect, by forming the bottom wall of the storage chamber in a dome shape, stress concentration areas are less likely to occur on the bottom wall when the internal pressure of the storage chamber increases.

[0059] REFERENCE SIGNS LIST 1 liquefied hydrogen storage tank 10 tank body 11 outer tank 11S outer tank side plate 12 inner tank 12S inner tank side plate 13 cold insulation layer 2 liquid barrier 23 protrusion 3 pump 51 storage chamber 55 bottom wall 6 inner member 63 heat insulation layer LH liquefied hydrogen AR arc surface

Claims

1. A liquefied hydrogen storage tank comprising: a tank body including an inner tank for storing liquefied hydrogen, and an outer tank formed between the inner tank and the outer tank with a cold insulation layer interposed therebetween; a liquid barrier erected to surround the outer periphery of the tank body; a pump that discharges liquefied hydrogen within the inner tank to the outside through a side plate of the inner tank; and a storage chamber for accommodating the pump, wherein the liquid barrier includes a protrusion portion protruding radially outward, the storage chamber is located between the outer periphery of the protrusion portion and the side plate of the inner tank, and the horizontal cross section of the storage chamber is circular.

2. A liquefied hydrogen storage tank as claimed in claim 1, wherein the outer peripheral surface of the protrusion portion has an arcuate surface in the horizontal direction.

3. A liquefied hydrogen storage tank as claimed in claim 1 or 2, wherein an inner member is provided on a wall surface that divides the storage chamber.

4. A liquefied hydrogen storage tank as claimed in claim 3, wherein the protrusion is made of prestressed concrete, and the inner member is resistant to low temperatures.

5. A liquefied hydrogen storage tank as claimed in claim 3, wherein the protrusion is made of concrete, and the inner member has resistance to low temperatures and strength sufficient to withstand the internal pressure generated in the storage chamber.

6. A liquefied hydrogen storage tank as claimed in claim 3, wherein the inner member is made of a metal member, and further comprises a heat insulating layer disposed on the inside or outside of the inner member.

7. A liquefied hydrogen storage tank as claimed in claim 1, wherein the storage chamber includes a bottom wall having a downwardly convex dome shape.

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