Liquefied hydrogen storage tank

Abstract

To enhance tolerance to internal pressure rise of a pump storage chamber when liquefied hydrogen enters the pump storage chamber provided inside a dike.SOLUTION: A liquefied hydrogen storage tank 1 includes: a tank body 10 including an inner tank 12 for storing liquefied hydrogen LH, and an outer tank 11 formed with a cold insulation layer 13 interposed between the inner tank 12 and the outer tank 11; a dike 2 erected to surround an outer periphery of the tank body 10; a pump 3 for delivering the liquefied hydrogen LH in the inner tank 12 to the outside via an inner tank side plate 12S of the inner tank 12; and a storage chamber 51 for storing the pump 3. The dike 2 includes a protrusion 23 protruding outward in a radial direction, the storage chamber 51 is located inside between an outer peripheral surface of the protrusion 23 and the inner tank side plate 12S, and a horizontal cross section of the storage chamber 51 is circular.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] As a storage facility for low-temperature liquefied gas such as liquefied hydrogen or liquefied natural gas, a liquefied gas storage tank is known that includes a flat-bottom tank body that stores the liquefied gas and a liquid containment dike that surrounds the outer periphery of the tank body. The liquid containment dike is constructed for the purpose of preventing the stored liquefied gas from leaking out to the surroundings of the tank in the unlikely event that the tank body is damaged. A pump for discharging the liquefied gas from within the tank body is attached to the liquefied gas storage tank (for example, Patent Document 1).

[0003] When the liquefied gas to be stored is liquefied hydrogen, it may be difficult to install the pump in 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 provided that penetrates the tank body and the liquid barrier, and a pump storage chamber is provided 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 the operation of the pump. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-132619 A Summary of the Invention [Problem to be solved by the invention]

[0005] When the above tank structure is adopted, it is possible 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 and prevented from diffusing into the atmosphere. However, measures are required to prevent the internal pressure of the pump chamber from increasing as the leaked liquefied hydrogen accumulates in the pump chamber.

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

[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 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. Effect of the Invention

[0008] The liquefied hydrogen storage tank disclosed herein 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. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a cross-sectional view showing a liquefied hydrogen storage tank according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Diagram 3] 3(A) and (B) are partial cross-sectional views showing modified examples of the protruding portion of the liquid retaining dike. [Figure 4] FIG. 4 is a cross-sectional view of a pump chamber having an inner member. [Diagram 5] FIG. 5 is a cross-sectional view showing a pump chamber having a heat insulating layer. [Figure 6] FIG. 6 is a cross-sectional view showing a pump chamber having a dome-shaped bottom wall. [Figure 7] FIG. 7 is a partial cross-sectional view showing a further modified example of the protruding portion of the liquid barrier. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] [Overall tank structure] Hereinafter, an embodiment of a liquefied hydrogen storage tank according to the present disclosure will 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 for storing liquefied hydrogen LH. The liquefied hydrogen storage tank 1 includes a tank body 10 having a multi-shell structure, a liquid barrier 2 erected so as to surround the outer periphery of the tank body 10, a pump 3 for discharging the liquefied hydrogen LH in the tank body 10 to the outside, and a storage chamber 51 for the pump 3 arranged within the structure of the liquid barrier 2. In FIG. 1, a double-shell tank is illustrated 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 contained in 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 forming 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 disposed concentrically. The tank body 10 may 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, an outer tank side plate 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 close 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 in which the liquefied hydrogen LH is actually stored. The inner tank 12 is a sealed body made of a metal such as stainless steel, and is surrounded by the outer tank 11 through a space of a predetermined interval that serves as the cold insulation layer 13. The inner tank 12 includes an inner tank bottom plate 12B, an inner tank side plate 12S, and an inner tank roof 12R. The inner tank bottom plate 12B has a disk-shaped shape with a smaller diameter than the outer tank bottom plate 11B. The inner tank side plate 12S is erected 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-shaped shape. The 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 is a layer for improving the cold insulation of the inner tank 12 by utilizing the gap between the outer tank 11 and the inner tank 12 as an insulating space. The cold insulation layer 13 may contain a powder insulation material or a solid insulation material. For example, the gap between the outer tank roof 11R and the inner tank roof 12R is filled with a powder insulation material such as granular perlite. The gap between the outer tank side plate 11S and the inner tank side plate 12S is filled with granular perlite and glass wool. The gap between the outer tank bottom plate 11B and the inner tank bottom plate 12B is filled with an insulating block material such as foam glass.

[0015] The cold insulation layer 13 is filled with hydrogen gas, helium gas, nitrogen gas, etc., together with a cold insulation material such as granular perlite. The gas to be filled is preferably a gas having a boiling point equal to or lower than that of the stored liquefied hydrogen LH, and from this viewpoint, 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 liquid barrier 2 prevents the stored liquefied hydrogen LH from leaking out to the tank periphery in the event that the tank body 10 is damaged. The liquid barrier 2 is a cylindrical concrete structure constructed on the tank foundation 21 and erected so as to surround the outer periphery of the tank body 10. It is preferable that reinforcing materials such as steel bars and PC (prestressed concrete) steel materials are incorporated into the concrete structure. In particular, it is particularly preferable to adopt a PC structure, since it is possible to construct a liquid barrier 2 with excellent strength. The liquid barrier 2 of this embodiment has a structure in which there is no separation distance between the outer periphery of the tank body 10, that is, a structure in which the liquid barrier 2 and the outer tank side plate 11S are integrated. In the event that the tank body 10 is damaged, the liquid barrier 2 prevents the liquefied hydrogen LH from leaking out, and the liquefied hydrogen LH is retained in the space of the cold insulation layer 13. That is, the space present inside the outer peripheral surface 2A of the dike 2 becomes a storage space for the leaked liquefied hydrogen LH.

[0017] The liquid barrier 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 liquid barrier 2 has an annular portion 22 and a protruding portion 23 as shape characteristics. The annular portion 22 is a cylindrical dam that surrounds the entire outer periphery of the tank body 10. FIG. 1 shows an example in which the height of the annular portion 22 is approximately the same as the height of the outer tank side plate 11S. The protruding portion 23 is provided corresponding to the installation location of the pump 3, and is a structural portion that is formed so that a part of the annular portion 22 protrudes radially outward and extends in the vertical direction. As shown in FIG. 2, the liquid barrier 2 has an outer peripheral surface 2A that 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 portion 23, and generates a pumping force to pump the liquefied hydrogen LH in the inner tank 12 to the outside through the side plate of the tank body 10. In this embodiment, the side plate is 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 liquid barrier 2, and dispenses the liquefied hydrogen LH stored in the inner tank 12. The extraction pipe 31 is a pipe 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 discharge pipe 32 is a pipe that extends upward inside the protruding portion 23, goes 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 discharge pipe 32 is connected to the outlet end of the pump 3, and the other end is connected to the inlet end of an apparatus that uses liquefied hydrogen LH as fuel or a transport truck.

[0020] In this embodiment, the pump 3 for dispensing the liquefied hydrogen LH in the tank body 10 is disposed outside the inner tank 12. This is because maintenance work is easier to perform than if the pump 3 were disposed in the storage space 10A in which the liquefied hydrogen LH is stored. In this case, a space for installing the pump 3 is required on the side of the tank body 10. In this embodiment, the above-mentioned protrusion portion 23 is formed in the liquid barrier 2, and a storage chamber 51 is provided inside the protrusion portion 23, 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 capable of accommodating the pump 3 and a part 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 covering almost the entire vertical length of the liquid retaining dike 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 have a circular cross section will be described in detail later.

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

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

[0024] The accommodation chamber 51 has an upper end opening 53 that opens on the top surface 23T of the protrusion portion 23. The upper part of the accommodation chamber 51 also serves as a passage portion 52. The passage portion 52 serves as a passage 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 passage portion 52 for the operator to move forward and backward. The upper end opening 53 is provided with an opening / closing door 54 for opening and closing the upper end opening 53. The opening / closing door 54 is normally closed and is opened during maintenance work, etc. By installing the opening / closing door 54, it is possible to prevent rainwater, dust, etc. from entering the accommodation chamber 51 and the passage portion 52, and to keep 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, an operator can easily access the pump 3 near the bottom of the storage chamber 51 through the passage 52, and maintenance work can be facilitated. In order to improve explosion-proofing, the space of the storage chamber 51 may be filled with an inert gas such as nitrogen gas.

[0026] According to the liquefied hydrogen storage tank 1 of 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 portion 23, form a liquid storage space that can store liquid leaking 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 leakage occurs due to damage to the tank body 10, the leaked liquid is confined in the liquid storage space, and the outflow of vaporized liquefied hydrogen LH can be suppressed.

[0027] In addition, a storage chamber 51 is provided in the protruding portion 23 of the liquid barrier 2, and the storage chamber 51 stores the pump 3 that discharges the liquefied hydrogen LH to the outside through the tank side plate. Therefore, maintenance work can be performed more easily than when the pump is installed in the inner tank 12. When the pump 3 is installed inside the inner tank 12 in the liquefied hydrogen storage tank 1 that stores the liquefied hydrogen LH, it is necessary to remove the pump 3 immersed in the liquefied hydrogen LH to the outside, so it is difficult to plan a maintenance method that is safe and easy to work with. In contrast, in this embodiment, the pump 3 is arranged 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, and maintenance work can be facilitated.

[0028] [Details of the ridges and containment chamber] In the liquefied hydrogen storage tank 1 having the above-mentioned structure, leakage of liquefied hydrogen LH from the inner tank 12 to the storage chamber 51 in the liquid barrier 2 may occur due to some factor. For example, damage to the extraction pipe 31 may be one factor in 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 the 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 Figs. 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 portion 23A of the protrusion 23 has a semicircular arc surface AR in the horizontal direction. The accommodation 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 accommodation chamber 51 approximately coincide with each other. The horizontal cross section of the accommodation chamber 51 is most preferably a perfect circle, but may be an ellipse or polygon that can be treated as a substantial circle, or may be 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 radial inside 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, it is possible to form an equilibrium state and resist the circumferential stress F2 generated by such force F1. If the horizontal cross section of the storage chamber 51 is rectangular, stress concentration occurs at the corners, and the degree to which the force F1 can be resisted is reduced. Therefore, the storage chamber 51 of this embodiment can withstand an increase in internal pressure when the liquefied hydrogen LH leaks, etc.

[0031] When the liquefied hydrogen LH leaks, 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 is no restriction on the external shape of the protrusion 23. Figures 3(A) and (B) show protrusions 231, 232 according to modified examples. The protrusion 231 in Figure 3(A) has a rectangular shape in horizontal cross section. The storage chamber 51 having a circular horizontal cross section is disposed inside the protrusion 231 that protrudes in a rectangular shape from the annular portion 22 of the liquid barrier 2. The protrusion 232 shown in Figure 3(B) has an external shape that is approximately circular in horizontal cross section, with an arc surface AR continuing to the protruding base from the annular portion 22. The circular storage chamber 51 is disposed concentrically with the protrusion 232.

[0033] [Containment chamber with inner member] In the above-described embodiment, it is desirable to provide an inner member on the wall surface that divides the storage chamber 51 in the liquid barrier 2. Fig. 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 portion 23 itself is the same as the protrusion portion 23 illustrated in Fig. 2. The storage chamber 51 provided inside the protrusion portion 23 is provided with the inner member 6 as a lining. The inner member 6 may line the storage chamber 51 over the entire vertical length, or may be provided up to a height equivalent to the liquid level of the liquefied hydrogen LH at the time of leakage.

[0034] The inner member 6 is desirably made of a material and has a thickness capable of providing a reinforcing function for the storage chamber 51 and / or a barrier function for the liquefied hydrogen LH. The reinforcing function is a function of improving the strength of the wall surface of the storage chamber 51. The barrier function is a function of preventing hydrogen from leaking from the storage chamber 51 to the outside through the protruding portion 23 when the liquefied hydrogen LH enters the storage chamber 51, and preventing low-temperature embrittlement of the protruding portion 23. The inner member 6 can be made of a metal material, a resin material, a ceramic material, or the like, so long as it provides the reinforcing function and / or barrier function. For example, low-temperature steel is one of the preferred constituent materials of the inner member 6. The inner member 6 may be made of a combination of multiple members.

[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 above case of (1), the protrusions 23 may be made of prestressed concrete, which has excellent strength, and the inner member 6 may be a member having resistance to low-temperature embrittlement (low-temperature resistance). For example, the inner member 6 may be made of low-temperature steel, which is insufficient for strength reinforcement but has a thickness that serves as a liner. In this case, the horizontal cross section of the inner wall itself that defines the storage chamber 51 is made circular so that the inner wall generates circumferential stress. According to the above embodiment (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 above case (2), the protrusion 23 is made of reinforced concrete, and the inner member 6 is a member having resistance to low-temperature embrittlement (low-temperature resistance) and strength to withstand the internal pressure generated in the storage chamber 51. For example, low-temperature steel having a thickness that is sufficient to withstand the internal pressure alone can be used as the inner member 6. In this case, since the inner surface of the inner member 6 becomes the inner wall that divides the storage chamber 51, the horizontal cross section of the inner surface of the inner member 6 is made circular. On the other hand, the space inside the protrusion 23 that houses the inner member 6 does not necessarily have to have a circular horizontal cross section. According to the above embodiment (2), the inner member 6 can suppress low-temperature embrittlement of the protrusion 23 when the liquefied hydrogen LH leaks, and the strength of the inner member 6 can handle the leaking liquid pressure. Therefore, the protrusion 23 can be made of reinforced concrete, which is relatively easy to construct. Alternatively, the protrusion 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, as layers corresponding to the inner member 6 described above, an outer liner 61 and an inner liner 62, and a heat insulating layer 63 disposed between these liners 61 and 62 are provided.

[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 hard urethane foam or insulating concrete. The insulating layer 63 may be formed as a space that can be evacuated and function 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, while the liners 61 and 62 serve as a barrier layer to prevent hydrogen leakage, the insulating layer 63 can suppress heat transfer from the storage chamber 51 to the outer peripheral surface of the protruding portion 23. Therefore, when the liquefied hydrogen LH enters the storage chamber 51, it is possible to suppress low-temperature embrittlement of the concrete constituting the protruding portion 23, and the formation of frost and liquefied air on the outer peripheral surface of the protruding portion 23 due to the heat transfer of the cold heat of the liquefied hydrogen LH, as well as the generation of thermal stress in the protruding portion 23.

[0040] [Other embodiments] Although the embodiment of the present disclosure has been described above, it is not limited to the above embodiment, and various modifications are possible. For example, in the above embodiment, the storage chamber 51 has a circular horizontal cross section, but the bottom wall of the storage chamber 51 may also be modified. FIG. 6 is a cross-sectional view showing the 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 installed on the bottom wall 55. According to the embodiment of FIG. 6, by making the bottom wall 55 of the storage chamber 51 dome-shaped, it is possible to prevent stress concentration from occurring on 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 liquid retaining dike 2. Alternatively, a plurality of protrusions 23 may be provided in the circumferential direction of the annular portion 22. Also, 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. Fig. 7 shows a protrusion 233 according to a modified example. The protrusion 233 includes a main body portion having a circular cross section and arranged 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 and 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 this 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 for accommodating the pump, wherein the liquid barrier includes a protrusion portion protruding radially outward, the storage chamber is located inside 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.

[0046] According to the first aspect, the housing chamber that houses the pump has a shape having a circular horizontal cross section. If the horizontal cross section of the inner wall of the housing chamber is circular, an equilibrium state can be formed and resistance can be formed against the circumferential stress generated on the inner wall due to an increase in the internal pressure of the housing chamber, so that the shape of the housing chamber can be maintained. Therefore, even if liquefied hydrogen leaks from the inner tank to the housing chamber, the housing chamber can be made 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 circumferential surface of the protrusion can be shaped to correspond 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 inner member can be provided to improve the strength of the wall of the storage chamber. 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 according to 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. Also, by providing the inner member with low-temperature resistance, deterioration of the protrusions due to low temperatures can be suppressed 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 of 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 resistance to low temperatures and to the internal pressure. This makes it possible to suppress low-temperature embrittlement of the protrusions, and the strength of the inner member can withstand the liquid pressure when liquefied hydrogen leaks. 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 includes 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 heat insulating layer suppresses heat transfer from the storage chamber to the outer circumferential surface of the protrusions. Therefore, when liquefied hydrogen enters the storage chamber, it is possible to suppress the formation of frost on the outer circumferential surface of the protrusions and the generation of liquefied air due to the heat transfer of the cold heat 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 containing chamber into a dome shape, stress concentration areas are less likely to occur on the bottom wall when the internal pressure of the containing chamber increases. [Explanation of symbols]

[0059] 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 layer 2 Liquid dike 23 Projection part 3. Pump 51 Containment Room 55 Bottom wall 6 Inner member 63 Thermal insulation layer LH Liquid hydrogen AR Arc Surface

Claims

1. A tank body including an inner tank for storing liquefied hydrogen and an outer tank formed between the inner tank and an outer tank via a cold insulation layer; A liquid retaining wall erected so as to surround the outer periphery of the tank body; a pump that pumps out liquefied hydrogen from the inner tank through a side plate of the inner tank; A housing chamber that houses the pump, The liquid barrier includes a protrusion portion protruding radially outward, a storage chamber located between an outer peripheral surface of the protrusion portion and a side plate of the inner tank, and a horizontal cross section of the storage chamber is circular.

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

3. The liquefied hydrogen storage tank according to claim 1 or 2, A liquefied hydrogen storage tank, comprising an inner member provided on a wall surface that divides the storage chamber.

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

5. The liquefied hydrogen storage tank according to claim 3, The protrusion is made of concrete, The inner member is resistant to low temperatures and has a strength sufficient to withstand the internal pressure generated in the storage chamber.

6. The liquefied hydrogen storage tank according to claim 3, The inner member is made of a metal material, The liquefied hydrogen storage tank further comprises an insulating layer disposed on the inside or outside of the inner member.

7. The liquefied hydrogen storage tank according to claim 1, The liquefied hydrogen storage tank, wherein the storage chamber includes a bottom wall having a downwardly convex dome shape.

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