Liquefied gas tank

Abstract

To realize work of taking out a pump from a tank with a simple structure.SOLUTION: A liquefied gas tank 1 is equipped with a tank body 10 that stores liquefied gas, a pump 3 that is disposed in the tank body 10 for delivering the liquefied gas, a pump barrel 2 that includes a cylindrical portion 21 extending upward from a position of the pump 3 and reaching the outside of the tank body 10 and an upper storage chamber 22 located above the cylindrical portion 21, a hoisting device 4 that is disposed in the upper storage chamber 22 and hoisting the pump 3 to the upper storage chamber 22 through the cylindrical portion 21, and an open / close valve 5 that is provided between the cylindrical portion 21 and the upper storage chamber 22 so as to open / close.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] A liquefied gas tank for storing liquefied gas such as liquefied hydrogen or liquefied natural gas is provided with a pump for discharging the liquefied gas in the tank. When discharging the liquefied gas through the tank roof, the pump is arranged inside the tank, and the liquefied gas is sent out to the outside through a cylindrical pump barrel penetrating the tank roof.

[0003] Here, for example, when performing work to remove the pump from inside the tank for pump maintenance, there may be a case where such work is carried out. Patent Document 1 below discloses a pump lifting device for lifting the pump through the pump barrel during such work. The pump lifting device of this Patent Document 1 includes a work deck constructed on the upper surface of the tank roof, a column member extending vertically fixed on the work deck, and a winch fixed to the column member and connected to the pump via a wire.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] According to the pump lifting device of the above Patent Document 1, the pump can be taken out of the tank through the pump barrel by winding the wire using the winch. However, since it is necessary to construct a structure such as a work deck or a column member on the tank roof to support the winch, there is a problem that the device is likely to be complicated or enlarged.

[0006] This disclosure is made in view of the circumstances described above, and aims to provide a liquefied gas tank that enables the removal of the pump from inside the tank with a relatively simple configuration. [Means for solving the problem]

[0007] To solve the aforementioned problems, a liquefied gas tank according to one aspect of the present disclosure comprises a tank body for storing liquefied gas, a pump disposed within the tank body for discharging the liquefied gas, a pump barrel including a cylindrical portion that houses the pump and extends upward from the pump's housing position to the outside of the tank body, and an upper housing chamber located above the cylindrical portion and defining a space capable of receiving the pump, a lifting device disposed within the upper housing chamber for lifting the pump into the upper housing chamber through the cylindrical portion, and an on / off valve provided between the cylindrical portion and the upper housing chamber so as to be openable and closable. [Effects of the Invention]

[0008] According to the liquefied gas tank of this disclosure, the operation of removing the pump from inside the tank can be achieved with a simple configuration. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram showing the structure of a liquefied gas tank according to one embodiment of the present disclosure. [Figure 2] This is a partially enlarged view of Figure 1 to show details of the pump barrel and its surrounding structure. [Figure 3] This is a diagram illustrating the procedure for removing the pump. [Figure 4] This is a diagram illustrating the procedure for installing a pump. [Figure 5] This figure illustrates a modified example of the above embodiment. [Modes for carrying out the invention]

[0010] Hereinafter, a liquefied gas tank according to an embodiment of the present disclosure will be described in detail with reference to the drawings. The liquefied gas tank of the present disclosure is a tank for storing low-temperature liquefied gases. The liquefied gases to be stored are, for example, liquefied hydrogen, liquid helium, liquid nitrogen, liquefied ammonia, liquefied natural gas, or liquefied petroleum gas. In particular, the liquefied gas tank according to the present disclosure is suitable as a tank for storing liquefied hydrogen.

[0011] [Overall structure of the tank] Figure 1 is a schematic diagram showing the structure of a liquefied gas tank 1 according to one embodiment of the present disclosure. The liquefied gas tank 1 is a tank for storing cryogenic liquefied hydrogen LH, and is a flat-bottomed tank with a multi-shell structure that is installed on the ground. The liquefied gas tank 1 comprises a tank body 10, a pump barrel 2, a pump 3, a lifting device 4, an on-off valve 5, and a gas replacement device 6. The tank body 10 is a dome-shaped container for storing liquefied hydrogen LH. The pump 3 is a submersible pump positioned inside the tank body 10 while immersed in liquefied hydrogen LH. The pump barrel 2 is a cylindrical body extending vertically through which the liquefied hydrogen LH discharged from the tank body 10 by the pump 3 flows. The lifting device 4 is a device for lifting the pump 3 through the pump barrel 2 when necessary for maintenance, etc. The on-off valve 5 is a valve that can be opened and closed in the middle of the pump barrel 2. The gas replacement device 6 is a device for replacing the gas in the space above the on-off valve 5 in the pump barrel 2 (the upper containment chamber 22, which will be described later).

[0012] The tank body 10 is a sealed body that defines a space inside for storing liquefied hydrogen LH. In Figure 1, the tank body 10 is simplified and shown as a single-shell structure, but the actual tank body 10 has a multi-shell structure such as a double-shell or triple-shell structure. In the case of a double-shell structure, the tank body 10 consists of an outer tank erected on a foundation and an inner tank enclosed within the outer tank. The liquefied hydrogen LH is stored inside the inner tank. A cooling layer is formed between the outer tank and the inner tank as an insulating space, and this cooling layer is filled with a powder insulation material such as granular perlite and a low-boiling point gas. In the case of a triple-shell structure, the tank body 10 has a structure that includes an intermediate tank between the outer tank and the inner tank.

[0013] Figure 2 is a partially enlarged view of Figure 1 to show details of the pump barrel 2 and its surrounding structure. As shown in Figures 1 and 2, the pump barrel 2 penetrates the tank roof 11 so as to connect the inside and outside of the tank body 10. That is, the pump barrel 2 is formed to extend vertically, penetrating the tank roof 11, from a height near the bottom inside the tank body 10 to a height above the tank roof 11. The pump barrel 2 functions as a discharge pipe for discharging liquefied hydrogen LH from inside the tank body 10 to the outside.

[0014] The pump barrel 2 comprises a cylindrical portion 21 located below the on-off valve 5 and an upper housing chamber 22 located above the on-off valve 5. In other words, the pump barrel 2 is divided into the cylindrical portion 21 and the upper housing chamber 22 by the on-off valve 5, which is installed midway along its vertical direction.

[0015] The cylindrical portion 21 is a straight cylindrical body with a substantially constant cross-section in the vertical direction, and is formed to extend upward from a position corresponding to the pump 3 inside the tank body 10 to the outside of the tank body 10 (above the tank roof 11). The cylindrical portion 21 has a lower end portion 21a that houses the pump 3 and an upper end portion 21b that protrudes above the tank roof 11. A discharge port 24 is provided protruding from the upper end portion 21b. The discharge port 24 is a port for discharging liquefied hydrogen L discharged when the pump 3 is operating to the outside.

[0016] The upper storage chamber 22 is connected to the upper end 21b of the cylindrical portion 21 via an on-off valve 5. The upper storage chamber 22 includes a storage chamber body 26 with an open top and a head plate 25 that covers the top opening of the storage chamber body 26. The head plate 25 corresponds to the ceiling member in this disclosure.

[0017] The containment chamber body 26 is a stepped cylindrical member formed such that the cross-sectional area of ​​the upper part is larger than the cross-sectional area of ​​the lower part. That is, as shown in Figure 2, the containment chamber body 26 has a small diameter portion 26a connected to the on / off valve 5, a large diameter portion 26b with an inner diameter larger than that of the small diameter portion 26a, and an intermediate portion 26c connecting the small diameter portion 26a and the large diameter portion 26b. The intermediate portion 26c is formed such that its inner diameter increases towards the upper part closer to the large diameter portion 26b.

[0018] The head plate 25 is a plate-shaped member that constitutes the ceiling of the upper storage chamber 22. The head plate 25 is detachably attached to the upper end of the storage chamber body 26 (large diameter section 26b) via bolts or the like so as to open and close the upper opening of the storage chamber body 26. A hanging handle 25a is provided protruding from the upper surface of the head plate 25.

[0019] The pump 3 is accommodated in the lower end portion 21a of the pump barrel 2 (cylindrical portion 21) and is disposed in the tank body 10 in a state of being immersed in the liquefied hydrogen L. A foot valve 23 for opening and closing an intake port, which is the lower surface opening, is attached to the lower end portion 21a of the pump barrel 2. The pump 3 is placed on the foot valve 23, and when the foot valve 23 descends under the weight of the pump 3, the intake port of the pump barrel 2 is opened. The pump 3 is driven in a state where the intake port is thus opened, takes in the liquefied hydrogen LH in the tank body 10 from the intake port, pumps it upward, and discharges the liquefied hydrogen LH to the outside through the pump barrel 2 (cylindrical portion 21).

[0020] The lifting device � is disposed in the upper accommodation chamber 22 of the pump barrel 2. The lifting device 4 is a winch capable of lifting the pump 3 accommodated in the lower end portion 21a of the pump barrel 2 (cylindrical portion 21) to the upper accommodation chamber 22. Specifically, the lifting device 4 includes a drum 41 rotatable about a horizontal axis and a suspension wire 42 connecting the drum 41 and the pump 3. The suspension wire 42 is wound around the drum 41 and is arranged to extend downward from the drum 41 to reach the pump 3. The drum 41 is a drum capable of rotating in a forward rotation direction for winding up the suspension wire 42 and a reverse rotation direction for pulling out the suspension wire 42, and is supported by a support member 43 fixed to the lower surface of the head plate 25. That is, the drum 41 is rotatably supported inside the upper accommodation chamber 22 by being attached to the lower surface of the head plate 25 via the support member 43. The lifting device 4 may further include a drive source for rotationally driving the drum 41 in the forward and reverse rotation directions. As the drive source, an appropriate one such as a pneumatic type using gas or an electric type using electric power may be used.

[0021] The on-off valve 5 is an openable and closable valve disposed between the cylindrical portion 21 and the upper accommodation chamber 22, and can be switched between an open state in which the cylindrical portion 21 and the upper accommodation chamber 22 communicate with each other and a closed state in which the two are blocked. In the figure, when the symbol representing the valve is painted black, it indicates that the valve is closed, and when the symbol representing the valve is not painted black, it indicates that the valve is open. As shown in FIGS. 1 and 2, during the operation of the liquefied gas tank 1, the on-off valve 5 is maintained in the open state. The suspension wire 42 is arranged to extend from the upper accommodation chamber 22 to the cylindrical portion 21 through the on-off valve 5 in this open state, and connects the pump 3 at the lower end portion 21a of the cylindrical portion 21 and the drum 41 in the upper accommodation chamber 22 to each other. On the other hand, when taking out the pump 3 from the tank body 10 for maintenance or the like, the pump 3 is lifted from the cylindrical portion 21 to the upper accommodation chamber 22 by the lifting device 4. At this time, the on-off valve 5 is maintained in the open state until the movement of the pump 3 to the upper accommodation chamber 22 is completed, and is switched to the closed state after the movement is completed. The on-off valve 5 has a valve body that can allow the passage of the pump 3 in the open state so that the pump 3 can move between the cylindrical portion 21 and the upper accommodation chamber 22. As such an on-off valve 5, a ball valve having a hollow ball-shaped valve body is suitable.

[0022] The gas replacement device 6 is a device that replaces the gas in the upper storage chamber 22 when necessary, such as when the pump 3 is withdrawn, and comprises a hydrogen gas supply source 61, a nitrogen gas supply source 62, a first inlet pipe 63, a second inlet pipe 64, a first outlet pipe 65, a second outlet pipe 66, and first to fourth valves 67A to 67D. The hydrogen gas supply source 61 is a supply source that supplies gas corresponding to the liquefied gas (in this case, liquefied hydrogen LH) stored in the tank body 10, i.e., hydrogen gas, and includes, for example, a pneumatic pump capable of pumping hydrogen gas. The nitrogen gas supply source 62 is a supply source that supplies nitrogen gas as an inert gas, and includes, for example, a pneumatic pump capable of pumping nitrogen gas. The first inlet pipe 63 is a pipe that connects the hydrogen gas supply source 61 and the upper storage chamber 22. The second inlet pipe 64 is a pipe that connects the nitrogen gas supply source 62 and the upper storage chamber 22. The first outlet pipe 65 and the second outlet pipe 66 are pipes connected to the upper containment chamber 22 for discharging the gas to be replaced from the upper containment chamber 22. The first valve 67A is a valve that can be opened and closed on the first inlet pipe 63, the second valve 67B is a valve that can be opened and closed on the second inlet pipe 64, the third valve 67C is a valve that can be opened and closed on the first outlet pipe 65, and the fourth valve 67D is a valve that can be opened and closed on the second outlet pipe 66.

[0023] The gas replacement device 6 replaces the gas in the upper storage chamber 22 by operating with the on-off valve 5 closed, that is, with communication between the cylindrical section 21 and the upper storage chamber 22 blocked. Specifically, the gas replacement device 6 can fill the upper storage chamber 22 with hydrogen gas supplied from the hydrogen gas supply source 61, or with nitrogen gas supplied from the nitrogen gas supply source 62. In other words, the upper storage chamber 22 can be switched between being filled with hydrogen gas and being filled with nitrogen gas. During gas replacement to change the gas in the upper storage chamber 22, the first to fourth valves 67A to 67D are opened as needed. On the other hand, during operation of the liquefied gas tank 1, as shown in Figures 1 and 2, the first to fourth valves 67A to 67D are all kept closed.

[0024] [Pump removal procedure] As mentioned above, the pump 3 may be removed from the tank body 10, for example, for maintenance. The details of this procedure will be explained using Figure 3.

[0025] Prior to the removal of pump 3 (Figure 3), the liquefied hydrogen LH in the pump barrel 2 is first pushed into the tank body 10. During the operation of the liquefied gas tank 1, liquefied hydrogen LH is present inside the pump barrel 2. Generally, except when discharging liquefied hydrogen LH, the liquefied hydrogen LH in the pump barrel 2 is at the same height as the liquid level in the tank body 10. From the viewpoint of reducing the lifting resistance of pump 3 or suppressing liquid entrapment, it is desirable that there is no liquid in the pump barrel 2 when pump 3 is removed. Therefore, in this embodiment, as preparation before removing pump 3, a gas corresponding to the stored liquefied gas (in this case, liquefied hydrogen LH), i.e., hydrogen gas, is supplied to the pump barrel 2 from the discharge port 24. At this time, the first to fourth valves 67A to 67D are all closed. Then, the liquefied hydrogen LH in the pump barrel 2 is pushed back into the tank body 10 by the hydrogen gas supplied from the discharge port 24. This results in the pump barrel 2 being completely filled with hydrogen gas. Note that this extrusion of liquefied hydrogen (LH) can be performed only as needed and can be omitted.

[0026] Next, as shown in step 1-1 of Figure 3, the pump 3 is lifted to the upper containment chamber 22 using the lifting device 4. During this lifting, the on-off valve 5 is kept open, just as it is during operation of the liquefied gas tank 1. The lifted pump 3 passes through the open on-off valve 5 and moves from the cylindrical part 21 of the pump barrel 2 to the upper containment chamber 22. Also, the first to fourth valves 67A to 67D are all kept closed until the movement (lifting) of the pump 3 to the upper containment chamber 22 is complete. As a result, the upper containment chamber 22 is kept filled with hydrogen gas until the movement (lifting) of the pump 3 is complete.

[0027] Next, as shown in step 1-2 of Figure 3, the gas in the upper containment chamber 22 is replaced from hydrogen gas to nitrogen gas. Specifically, the on-off valve 5 is switched from the open state to the closed state, and the second valve 67B and the third valve 67C are switched from the closed state to the open state. Meanwhile, the first valve 67A and the fourth valve 67D are kept in the closed state. As a result, with communication between the upper containment chamber 22 and the cylindrical section 21 blocked, nitrogen gas is introduced into the upper containment chamber 22 from the second inlet pipe 64. The introduced nitrogen gas fills the upper containment chamber 22, pushing the hydrogen gas that was present in the upper containment chamber 22 out to the first outlet pipe 65. In other words, the state in which the inside of the upper containment chamber 22 is filled is switched from a state in which it is filled with hydrogen gas to a state in which it is filled with nitrogen gas. The hydrogen gas pushed out through the first outlet pipe 65 is recovered, for example, in a predetermined recovery device connected to the first outlet pipe 65.

[0028] Next, as shown in step 1-3 of Figure 3, the head plate 25 is removed from the upper storage chamber 22, and the lifting device 4 and pump 3 are transported out together with the head plate 25. Specifically, with the first to fourth valves 67A to 67D all closed, the fixing means such as bolts that secure the head plate 25 to the storage chamber body 26 are released, and the head plate 25 is removed from the storage chamber body 26 and transported out using an external transport device such as a pre-prepared winch. For example, with the wire W extending from the external transport device attached to the lifting handle 25a of the head plate 25, the external transport device is operated to transport the head plate 25 to a predetermined destination. Once the head plate 25 is removed by this transport, the top surface of the upper storage chamber 22 (storage chamber body 26) is opened, and the gas (nitrogen gas) inside the upper storage chamber 22 is replaced with air as appropriate. Here, the lifting device 4 is fixed to the head plate 25, and the lifting device 4 holds the pump 3 by a lifting wire 42. Therefore, when the head plate 25 is removed, the lifting device 4 and the pump 3 are also removed along with the head plate 25.

[0029] With the above steps completed, the process of removing pump 3 from the tank body 10 is finished. The removed pump 3 will be subjected to maintenance and other prescribed procedures at the destination.

[0030] [Pump installation work] Next, the process of installing the pump 3 onto the tank body 10 will be explained using Figure 4.

[0031] First, the lifting device 4 and pump 3 are inserted into the upper containment chamber 22. This operation is the reverse of steps 1-3 in Figure 3, and is achieved by fixing the head plate 25, which includes the lifting device 4 and pump 3, to the upper surface of the containment chamber body 26. At this time, the on-off valve 5 and the first to fourth valves 67A to 67D are all kept closed. With the head plate 25 fixed in this state, air is trapped inside the upper containment chamber 22.

[0032] Next, as shown in step 2-1 of Figure 4, the gas in the upper containment chamber 22 is replaced from air to nitrogen gas. Specifically, while keeping the on-off valve 5, the first valve 67A, and the fourth valve 67D closed, the second valve 67B and the third valve 67C are opened. As a result, nitrogen gas is introduced into the upper containment chamber 22 from the second inlet pipe 64, and air is discharged from the upper containment chamber 22 through the first outlet pipe 65. In other words, the state in which the upper containment chamber 22 is filled is switched from being filled with air to being filled with nitrogen gas.

[0033] Next, as shown in step 2-2 of Figure 4, the gas in the upper containment chamber 22 is replaced from nitrogen gas to hydrogen gas. Specifically, while keeping the on-off valve 5 in the closed state, the first valve 67A and the fourth valve 67D are switched from the closed state to the open state, and the second valve 67B and the third valve 67C are switched from the open state to the closed state. As a result, hydrogen gas is introduced into the upper containment chamber 22 from the first inlet pipe 63, and nitrogen gas is discharged from the upper containment chamber 22 through the second outlet pipe 66. In other words, the state in which the upper containment chamber 22 is filled is switched from being filled with nitrogen gas to being filled with hydrogen gas.

[0034] Next, as shown in step 2-3 of Figure 4, the pump 3 is lowered from the upper housing chamber 22 to the lower end 21a of the cylindrical section 21 using the lifting device 4. Before this lowering, the first to fourth valves 67A to 67D are all closed, and the on-off valve 5 is switched from the closed state to the open state. The pump 3 moves from the upper housing chamber 22 to the lower end 21a of the cylindrical section 21, passing through the on-off valve 5, which is in the open state.

[0035] As a result, the pump 3 is returned to its proper storage position (the lower end 21a of the cylindrical portion 21) within the pump barrel 2, and the process of installing the pump 3 into the tank body 10 is completed.

[0036] [Effects and Effects] As described above, in this embodiment, a lifting device 4 capable of lifting the pump 3 from the cylindrical portion 21 of the pump barrel 2 to the upper storage chamber 22 is arranged in the upper storage chamber 22, and an on / off valve 5 is arranged between the cylindrical portion 21 and the upper storage chamber 22. This configuration has the advantage that the operation of removing the pump 3 from inside the tank body 10 can be achieved with a relatively simple setup.

[0037] In other words, according to the configuration of this embodiment in which the lifting device 4 and the on-off valve 5 are applied to the pump barrel 2, when removing the pump 3 from the tank body 10 for maintenance, etc., the pump 3 can be moved from the cylindrical part 21 of the pump barrel 2 to the upper storage chamber 22 by lifting the pump 3 with the on-off valve 5 open using the lifting device 4, and the pump 3 can be transported out from the upper storage chamber 22. In particular, since the lifting device 4 is located in the upper storage chamber 22 of the pump barrel 2, unlike when the lifting device 4 is located outside the pump barrel 2, it becomes unnecessary to construct a separate structure on the tank roof 11 to support the lifting device 4. In other words, in this embodiment, the removal of the pump 3 from the tank body 10 is made easy, so the man-hours or costs associated with maintenance of the pump 3 can be reduced.

[0038] Furthermore, after the pump 3 has been lifted to the upper storage chamber 22, the communication between the upper storage chamber 22 and the cylindrical section 21 can be blocked by switching the on / off valve 5 from the open state to the closed state. This prevents air from flowing from the upper storage chamber 22 into the cylindrical section 21, while allowing the head plate 25 to be removed from the upper storage chamber 22 and the upper storage chamber 22 to be opened, and the pump 3 to be easily removed from the upper storage chamber 22. In other words, in this embodiment, the pump 3 can be easily removed from the tank body 10 while preventing air from entering the tank body 10.

[0039] Furthermore, in this embodiment, since the lifting device 4 is attached to the lower surface of the detachable head plate 25 that constitutes the ceiling of the upper storage chamber 22, after lifting the pump 3 up to the upper storage chamber 22 using the lifting device 4, the pump 3 together with the head plate 25 can be easily removed from the upper storage chamber 22 by removing the head plate 25 from the storage chamber body 26.

[0040] Furthermore, in this embodiment, a gas replacement device 6 capable of filling the upper containment chamber 22 with hydrogen gas or nitrogen gas is applied to the pump barrel 2, thereby preventing improper gas inflow and outflow when the pump 3 is removed and installed.

[0041] For example, when removing the pump 3, the gas in the upper storage chamber 22 is replaced with nitrogen gas, an inert gas, before the pump 3 is removed from the upper storage chamber 22 (see Figure 3), thereby preventing the gas corresponding to the stored liquefied gas (liquefied hydrogen LH), i.e., hydrogen gas, from being dispersed into the atmosphere. On the other hand, when installing the pump 3, the gas in the upper storage chamber 22 is replaced with hydrogen gas before the pump 3 is lowered from the upper storage chamber 22 into the cylindrical section 21 (see Figure 4), thereby preventing gases other than hydrogen gas from being mixed into the tank body 10.

[0042] [Differentiation] While preferred embodiments of the present disclosure have been described above, the disclosure is not limited thereto, and variations such as the following are possible.

[0043] In the above embodiment, the lifting device 4 was attached to the lower surface of the head plate 25 that constitutes the ceiling of the upper storage chamber 22. However, the lifting device 4 only needs to be located inside the upper storage chamber 22, and its attachment point is not limited to the head plate 25. For example, the lifting device 4 may be detachably attached to the inner wall of the storage chamber body 26.

[0044] In the above embodiment, assuming that the liquefied gas stored in the liquefied gas tank 1 is liquefied hydrogen LH, a gas replacement device 6 capable of replacing the gas in the upper containment chamber 22 of the pump barrel 2 with hydrogen gas or nitrogen gas was applied to the pump barrel 2. However, the gas replacement device only needs to be capable of replacing the gas in the upper containment chamber with a gas corresponding to the liquefied gas or an inert gas, and the type of replacement gas can be changed as appropriate to that extent.

[0045] In the above embodiment, a single on-off valve 5 is provided between the cylindrical portion 21 of the pump barrel 2 and the upper storage chamber 22, but multiple on-off valves may be provided. For example, a first on-off valve may be attached to the upper end of the cylindrical portion 21, a second on-off valve may be attached to the lower end of the upper storage chamber 22, and a short cylindrical intermediate chamber may be provided between the first and second on-off valves. This has the advantage that when gas replacement is performed in the upper storage chamber 22, the inflow and outflow of gas between the upper storage chamber 22 and the cylindrical portion 21 can be prevented in multiple ways.

[0046] Although not specifically mentioned in the above embodiments, when discharging liquefied hydrogen LH from the tank body 10 using the pump 3, the liquid level of liquefied hydrogen LH in the pump barrel 2 may rise above the height of the discharge port 24. In particular, if the head of the pump 3 is sufficiently secured to expedite the discharge, the liquefied hydrogen LH may reach the height of the lifting device 4 beyond the on-off valve 5. Figure 5 illustrates a structure that incorporates measures to avoid such a situation. The upper storage chamber 122 shown in this figure has increased vertical dimensions compared to the upper storage chamber 22 in the above embodiments (Figures 1 to 4). An annular orifice 126 is also provided inside the upper storage chamber 122. The orifice 126 is provided so as to protrude radially inward from the inner wall of the upper storage chamber 122 in the vertical middle section, dividing the interior of the upper storage chamber 122 into two vertical sections. In other words, the upper chamber 122 has an orifice 126, a first divided chamber 122A formed above the orifice 126, and a second divided chamber 122B formed below the orifice 126. The first divided chamber 122A has space to accommodate the lifting device 4. The second divided chamber 122B has space to receive the pump 3 (shown by a dashed line in Figure 5) which has been lifted up to above the on-off valve 5 by the lifting device 4.

[0047] An opening 126a is formed in the center of the orifice 126 through which the suspension wire 42 can pass. Since the area of ​​the opening 126a is sufficiently smaller than the cross-sectional area of ​​the upper storage chamber 22, a large flow resistance acts on the liquefied hydrogen LH passing through the opening 126a. This prevents the liquefied hydrogen LH from reaching the lifting device 4 above the orifice 126 when it is being dispensed.

[0048] In the modified example shown in Figure 5, the orifice 126 needs to be removed from the upper housing chamber 122 in order to allow the pump 3 to be removed from the upper housing chamber 122. In other words, the orifice 126 is detachable from the upper housing chamber 122. Specifically, in the modified example shown in Figure 5, the upper housing chamber 122 has a two-part structure in which its first divided chamber 122A and second divided chamber 122B are flange-connected, and the orifice 126 is attached between the flange F1 of the first divided chamber 122A and the flange F2 of the second divided chamber 122B via fastening members such as bolts. When removing the pump 3, the orifice 126 can be removed from the upper housing chamber 122 by simultaneously removing it from flanges F1 and F2.

[0049] [summary] The above embodiments and their modified forms can be summarized as follows.

[0050] The liquefied gas tank comprises a tank body for storing liquefied gas, a pump disposed within the tank body for discharging the liquefied gas, a pump barrel including a cylindrical portion that houses the pump and extends upward from the pump's housing position to the outside of the tank body, and an upper housing chamber located above the cylindrical portion and defining a space capable of receiving the pump, a lifting device disposed within the upper housing chamber for lifting the pump into the upper housing chamber through the cylindrical portion, and an on / off valve provided between the cylindrical portion and the upper housing chamber so as to be openable and closable.

[0051] According to this embodiment, when removing the pump from the tank body for maintenance or other purposes, the pump can be moved from the cylindrical portion of the pump barrel to the upper storage chamber by lifting the pump with the lifting device while the on / off valve is open, and the pump can then be removed from the upper storage chamber. In particular, since the lifting device is located in the upper storage chamber of the pump barrel, unlike when the lifting device is located outside the pump barrel, it becomes unnecessary to construct a separate structure on the tank roof to support the lifting device. In other words, according to this disclosure, the removal of the pump from the tank body becomes easier, and the man-hours or costs associated with pump maintenance can be reduced.

[0052] Furthermore, after the pump has been lifted to the upper chamber, the communication between the upper chamber and the cylindrical section can be blocked by switching the on / off valve from the open to the closed position. This prevents air from flowing from the upper chamber into the cylindrical section while allowing the upper chamber to be opened, and the pump to be easily removed from the upper chamber. In other words, according to this disclosure, the pump can be easily removed from the tank body while preventing air from entering the tank body.

[0053] Preferably, the upper storage chamber comprises a storage chamber body with an open top and a removable ceiling member that covers the top opening of the storage chamber body, and the lifting device is attached to the lower surface of the ceiling member.

[0054] In this embodiment, after lifting the pump to the upper housing chamber using a lifting device, the ceiling member can be removed from the housing chamber body, allowing the pump to be easily transported out of the upper housing chamber together with the ceiling member.

[0055] Preferably, the liquefied gas tank further comprises a gas replacement device capable of switching between a state in which the interior of the upper storage chamber is filled with a gas corresponding to the liquefied gas to be stored and a state in which it is filled with an inert gas.

[0056] In this embodiment, it is possible to prevent improper gas inflow and outflow during pump removal and installation. For example, when removing the pump, by replacing the gas in the upper storage chamber with an inert gas before removing the pump from the upper storage chamber, it is possible to prevent the gas corresponding to the stored liquefied gas from being dispersed into the atmosphere. On the other hand, when installing the pump, by replacing the gas in the upper storage chamber with a gas corresponding to the liquefied gas before lowering the pump from the upper storage chamber into the cylindrical section, it is possible to prevent a gas different from the gas corresponding to the liquefied gas from being mixed into the tank body.

[0057] Preferably, the upper housing chamber has an annular orifice projecting radially inward from the inner wall of its intermediate vertical portion, a first partitioned chamber formed above the orifice and housing the lifting device, and a second partitioned chamber formed below the orifice and capable of receiving the pump.

[0058] In this embodiment, since an orifice is provided inside the upper containment chamber, it is possible to prevent the liquid level of the liquefied gas from reaching the height of the lifting device when the liquefied gas is discharged using the pump. Furthermore, the lifting device can be housed in the first division chamber above the orifice, and the pump lifted by the lifting device can be received in the second division chamber below the orifice. [Explanation of symbols]

[0059] LH Liquefied Hydrogen (Liquefied Gas) 1. Liquefied gas tank 2 pump barrels 3 pumps 4. Lifting device 5. Shut-off valves 6. Gas replacement device 10 Tank body 21 Cylindrical part 22 Upper containment chamber 25. Head plate (ceiling component) 26 Main body of the containment chamber 122 Upper containment chamber 122A 1st division room 122B 2nd division room 126 Orifice

Claims

1. The tank body for storing liquefied hydrogen, A pump is placed inside the tank body to discharge the liquefied hydrogen, A pump barrel including a cylindrical portion that houses the pump and extends upward from the pump's housing position to the outside of the tank body, and an upper housing chamber located above the cylindrical portion and defining a space capable of receiving the pump, A lifting device is provided, which is located in the upper containment chamber and lifts the pump into the upper containment chamber through the cylindrical portion. An opening / closing valve is provided between the cylindrical portion and the upper storage chamber so as to be openable and closable, The system includes a foot valve that opens and closes the intake port for liquefied hydrogen at the lower end of the cylindrical portion, The upper storage chamber is a liquefied gas tank that can be connected to both a hydrogen gas source and a nitrogen gas source.

2. In the liquefied gas tank according to Claim 1, The upper storage chamber comprises a storage chamber body with an open top and a removable ceiling member that covers the top opening of the storage chamber body. The lifting device is a liquefied gas tank attached to the lower surface of the ceiling member.

3. In the liquefied gas tank according to claim 1 or 2, A liquefied gas tank further comprising a gas exchange device that includes a hydrogen gas supply source and a nitrogen gas supply source, and is capable of switching between a state in which the interior of the upper containment chamber is filled with hydrogen gas and a state in which it is filled with nitrogen gas.

4. The tank body for storing liquefied gas, A pump is placed inside the tank body to discharge the liquefied gas, A pump barrel including a cylindrical portion that houses the pump and extends upward from the pump's housing position to the outside of the tank body, and an upper housing chamber located above the cylindrical portion and defining a space capable of receiving the pump, A lifting device is provided, which is located in the upper containment chamber and lifts the pump into the upper containment chamber through the cylindrical portion. The system includes an opening / closing valve that is provided between the cylindrical portion and the upper storage chamber, A liquefied gas tank having an annular orifice projecting radially inward from the inner wall of its upper intermediate portion, a first divided chamber formed above the orifice and housing the lifting device, and a second divided chamber formed below the orifice and capable of receiving the pump.

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