Liquefied gas tank

Abstract

To prevent mixing of air into a pump barrel when taking out a pump for delivery of a liquefied gas from the inside of a tank.SOLUTION: A liquefied gas tank 1 includes: a tank body 10 for storing a liquefied gas; a pump barrel 2 penetrating the tank body 10 in the vertical direction; a pump 3 installed in the tank body 10, and for delivering the liquefied gas stored in the tank body 10 through the pump barrel 2; a chamber 4 installed on a tank roof 11 so as to cover a barrel opening 2H of the pump barrel 2; a suspension device 5 installed in the chamber 4, and for suspending the pump 3 into a space 4A in the chamber through the pump barrel 2; and a gas replacement device 6 for replacing the space 4A in the chamber at least with a gas environment of the liquefied gas to be stored or into an inert gas environment.SELECTED DRAWING: Figure 2

Description

【Technical Field】 【0001】 The present disclosure relates to a liquefied gas tank for storing liquefied gas at low temperature. 【Background Art】 【0002】 For example, a liquefied gas tank for storing liquefied gas such as liquefied hydrogen or liquefied natural gas needs to be equipped with a pump for discharging the liquefied gas in the tank. When discharging the liquefied gas through the tank roof, the pump is installed inside the tank, and the liquefied gas is sent out to the outside through a cylindrical pump barrel penetrating the tank roof (for example, Patent Document 1). 【0003】 For maintenance work of the pump, etc., it may be necessary to remove the pump from inside the tank. In this case, the pump is lifted through the pump barrel, and the pump is removed from the barrel opening at the upper end of the pump barrel. 【Prior Art Documents】 【Patent Documents】 【0004】 【Patent Document 1】 Japanese Patent Application Laid-Open No. 2017-132619 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0005】 When removing the pump for discharging the liquefied gas from inside the tank, it is desirable not to mix air into the pump barrel. In particular, when the liquefied gas stored in the tank is cryogenic liquefied hydrogen, various problems including safety problems occur because the air entering the barrel from the barrel opening is liquefied or solidified. 【0006】 An object of the present disclosure is to provide a liquefied gas tank capable of preventing the mixing of air into the pump barrel when removing the pump for discharging the liquefied gas from inside the tank. 【Means for Solving the Problems】 【0007】 A liquefied gas tank according to one aspect of the present disclosure comprises a tank body for storing liquefied gas, a pump barrel penetrating the tank body vertically, a pump installed inside the tank body for discharging the liquefied gas stored inside the tank body through the pump barrel, a chamber installed outside the tank body so as to cover the barrel opening at the upper end of the pump barrel, a lifting device installed outside the tank body for lifting the pump into the chamber through the pump barrel, and a gas replacement device for replacing the chamber with at least the gas environment of the stored liquefied gas or an inert gas environment. The lifting device provides a pump inlet / outlet for transporting the pump from inside the chamber to the outside or from the outside into the chamber, It is equipped with. [Effects of the Invention] 【0008】 According to this disclosure, it is possible to provide a liquefied gas tank that can prevent air from entering the pump barrel when removing the pump for discharging liquefied gas from inside the tank. [Brief explanation of the drawing] 【0009】 [Figure 1] Figure 1 is a schematic diagram of the structure of a liquefied gas tank according to this disclosure, and shows the tank body in cross-section. [Figure 2] Figure 2 is a schematic diagram showing the inside of the chamber installed outside the tank body. [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 gas. The liquefied gas to be stored is, for example, liquefied hydrogen, liquid helium, liquid nitrogen, liquefied natural gas, liquefied petroleum gas, or liquefied ammonia. 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 the liquefied gas tank 1 according to this 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 for storing liquefied hydrogen LH, a pump barrel 2 which is a structure for discharging liquefied hydrogen LH from the tank body 10, a submersible pump 3 which is installed inside the tank body 10 and immersed in the liquefied hydrogen LH, and a chamber 4 which is installed outside the tank body 10. In Figure 1, a portion of the tank body 10 is shown in cross-section. 【0012】 The tank body 10 has a storage space for storing liquefied hydrogen LH. Although Figure 1 shows a simplified single-shell structure, 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, an inner tank enclosed within the outer tank, and a cooling layer between the outer tank and the inner tank. The liquefied hydrogen LH is stored inside the inner tank. The 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 an intermediate tank between the outer tank and the inner tank. In addition, the tank body 10 may be a tank with a shape other than a flat bottom, or a tank that is buried underground, etc. 【0013】 The pump barrel 2 is a cylindrical body installed so as to penetrate the tank body 10 vertically, and serves as a discharge pipe for discharging liquefied hydrogen LH from the tank body 10 to the outside. The pump barrel 2 comprises a barrel interior space 2A, which is the internal space through which the liquefied hydrogen LH flows, a lower end portion 21 located near the bottom plate of the tank body 10 and immersed in the liquefied hydrogen LH, and an upper end portion 22 that extends upward through the tank roof 11. A portion of the upper end portion 22 is contained within the chamber 4. The barrel interior space 2A extends vertically between the lower end portion 21 and the upper end portion 22 and has an inner diameter that allows the pump 3 to pass through. 【0014】 Pump 3 is housed in the barrel space 2A near the lower end 21. A foot valve 23 is attached to the intake opening at the lower end 21 of the pump barrel 2. Pump 3 is positioned on top of the foot valve 23, and the weight of the pump 3 causes the foot valve 23 to hang down, opening the intake opening at the lower end 21. Pump 3 takes in liquefied hydrogen LH from the tank body 10, increases the pressure, and sends the liquefied hydrogen LH into the barrel space 2A. 【0015】 A discharge port 24 is provided near the upper end 22 of the pump barrel 2. The upper end of the pump barrel 2, which is housed in the chamber 4, is provided with a barrel opening 2H that connects the internal barrel space 2A with the external space. When the liquefied gas tank 1 is in operation, the barrel opening 2H is sealed by the head plate 25. When the pump 3 is operated, liquefied hydrogen LH is discharged from the internal barrel space 2A through the discharge port 24. 【0016】 On the other hand, during maintenance work on the pump 3, the head plate 25 is removed and the barrel opening 2H is opened. The pump 3 is lifted through the pump barrel 2 and removed from the barrel opening 2H. When the weight of the pump 3 is no longer applied due to the lifting, the foot valve 23 rises and seals the intake opening at the lower end 21. After the maintenance work is completed, the pump 3 is lowered through the pump barrel 2 from the barrel opening 2H and installed on top of the foot valve 23. After that, the barrel opening 2H is sealed with the head plate 25. 【0017】 Chamber 4 is installed on the tank roof 11 at the position where the pump barrel 2 penetrates the tank body 10. Chamber 4 is installed so as to cover the barrel opening 2H at the upper end of the pump barrel 2, which is sealed by the head plate 25. To "cover" the barrel opening 2H means, for example, to surround the barrel opening 2H with a space having a larger cross-sectional area than the opening area of ​​the barrel opening 2H. In this embodiment, an example is shown in which Chamber 4 is installed so that the upper, side, and lower parts of the barrel opening 2H are located within the chamber interior space 4A, which is a sealed space enclosed by Chamber 4. 【0018】 As described above, when removing the pump 3 installed inside the tank body 10 during maintenance work, etc., it is necessary to open the barrel opening 2H. At this time, air may enter the pump barrel 2. In this embodiment, since the tank body 10 stores liquefied hydrogen LH, the air (nitrogen and oxygen) that enters the pump barrel 2 will liquefy or solidify, causing various problems, including safety issues. Therefore, in this embodiment, a chamber 4 is installed to prevent air from entering the pump barrel 2 when removing the pump 3 from inside the tank body 10. With the installation of the chamber 4, even when the head plate 25 is removed during maintenance work, etc., the barrel interior space 2A and the atmosphere are not directly connected through the barrel opening 2H, and the chamber interior space 4A is interposed between them. The detailed structure of the chamber 4 will be described below. 【0019】 [Detailed structure of the chamber] Figure 2 is a schematic diagram showing the internal structure of chamber 4. Chamber 4 includes the chamber body 41, a spare chamber 42, an opening / closing door 43 (inlet), an inner door 44, a pump inlet / outlet 45, and a temporary pump storage area 46. A lifting device 5 for lifting the pump 3 is located inside chamber 4. A gas replacement device 6 capable of supplying inert gas to chamber 4 is also attached. 【0020】 Chamber 4 is assembled on a deck 40 installed on the tank roof 11. The deck 40 is installed on the tank roof 11 so as to surround the upper end portion 22 of the pump barrel 2. The deck 40 includes a vertical frame 401 that stands on the tank roof 11 and serves as a support column for supporting the chamber 4 below, and a horizontal frame 402 supported by the vertical frame 401. The horizontal frame 402 is installed at a position lower than the barrel opening 2H and supports the bottom surface of the chamber 4. 【0021】 The chamber body 41 partitions a chamber inner space 4A which is a closed space except for an opening for intake and exhaust of the replacement gas. Regarding the shape of the chamber body 41, there is no limitation as long as it is installed so as to cover the barrel opening 2H and a working space can be secured, and for example, it can be set to a rectangular parallelepiped shape, a fan shape, a cylindrical shape, a semi-circular shape, a gable roof shape. In FIG. 2, a rectangular parallelepiped chamber body 41 is illustrated, and the chamber body 41 includes a ceiling wall 411, an inner side wall 412, an outer side wall 413, a bottom wall 414, and a radial side wall 415. 【0022】 The top wall 411 demarcates the ceiling surface of the chamber body 41, and the bottom wall 414 demarcates the bottom surface of the chamber body 41. Passing through the bottom wall 414, the upper end 22 of the pump barrel 2 enters the inner space 4A of the chamber. In FIG. 2, the head plate 25 is open, showing a state where the barrel opening 2H of the pump barrel 2 opens into the inner space 4A of the chamber. Below the bottom plate 414, a telescopic tube 26 is externally fitted to the pump barrel 2. The upper end of the telescopic tube 26 is airtightly attached to the bottom plate 414, and the lower end is airtightly attached to the outer periphery of the pump barrel 2. Since the tank body 10 expands and contracts in the direction toward the center of the tank due to heat shrinkage, relative displacement occurs with respect to the permanent chamber 4. The telescopic tube 26 is provided to absorb the relative displacement and ensure the airtightness of the inner space 4A of the chamber. Note that the telescopic tube 26 may also be arranged above the bottom plate 414, that is, in the inner space 4A of the chamber. The inner wall 412 is the side wall on the center side of the tank body 10. The outer wall 413 is the side wall on the radially outer side of the tank body 10. The radial side wall 415 is the side wall along the radial direction of the tank body 10, connecting the edges of the inner wall 412 and the outer wall 413 to each other. 【0023】 The chamber body 41 has a protruding portion 41T that protrudes radially outward from the outer periphery of the tank body 10, that is, from the side wall of the tank body 10. The protruding portion 41T is provided to facilitate the removal of the pump 3 lifted from the tank body 10. For the support of the protruding portion 41T, the horizontal frame 402 extends radially outward from the outer periphery of the tank body 10. The outer wall 413 is located radially outward of the side wall of the tank body 10. 【0024】 The side walls of the chamber body 41 are provided with an inlet 416 and an exhaust 417. In this embodiment, an example is shown in which the inlet 416 is provided on the inner wall 412 and the exhaust 417 is provided on the outer wall 413. Alternatively, the inlet 416 and exhaust 417 may be provided using the top wall 411, the outer wall 413, or the radial side wall 415. The inlet 416 is an opening for introducing replacement gas into the chamber space 4A of the chamber 4. The exhaust 417 is an opening for exhausting replacement gas from the chamber space 4A. 【0025】 The spare chamber 42 is installed adjacent to the inner wall 412 of the chamber body 41 and partitions the spare chamber space 4B. An opening / closing door 43 is installed on the side wall of the spare chamber 42. Furthermore, an inner door 44 is installed on the inner wall 412. The opening / closing door 43 and the inner door 44 are entrances that allow workers to access the inside of the chamber body 41. The spare chamber 42 is positioned between the opening / closing door 43 and the chamber body 41 and is provided to make it difficult for the environment of the chamber space 4A to directly communicate with the atmospheric environment outside the tank. During maintenance, etc., workers open the opening / closing door 43 to enter the spare chamber space 4B, close the opening / closing door 43, and then open the inner door 44 to enter the chamber space 4A of the chamber body 41. The spare chamber 42 is equipped with a spare chamber inlet 421 and a spare chamber exhaust vent 422 for replacing the environment of the spare chamber space 4B with a predetermined replacement gas environment. 【0026】 The pump inlet / outlet 45 is an opening used for loading and unloading the pump 3 into and out of the chamber 4. The pump inlet / outlet 45 is opened in the bottom wall 414 of the chamber body 41 at the protruding portion 41T. The pump inlet / outlet 45 is used when unloading the pump 3 from the chamber interior space 4A to the outside, or when unloading the pump 3 from the outside to the chamber interior space 4A. The pump inlet / outlet 45 is equipped with a door that is normally closed but is opened when loading or unloading the pump 3. 【0027】 The pump temporary storage section 46 is installed inside the chamber body 41 and is a storage section where the pump 3, which has been lifted from inside the tank body 10, is temporarily held. In this embodiment, the pump temporary storage section 46 is assembled to the bottom wall 414 and is exemplified as a small chamber capable of housing the pump 3. The lifted pump 3 is temporarily held inside the pump temporary storage section 46 before being removed from the pump inlet / outlet 45. During this time, it is possible to purge any liquefied hydrogen LH remaining inside the pump 3. To facilitate the purging, it is desirable to provide an inert gas inlet and exhaust port in the pump temporary storage section 46. Note that the pump temporary storage section 46 may be a temporary storage space installed in an appropriate location inside the chamber body 41, rather than a small chamber. 【0028】 The lifting device 5 is installed near the top wall 411 inside the chamber body 41. The lifting device 5 may be installed outside the tank body 10, or outside the chamber body 41, for example, above the top wall 411. The lifting device 5 lifts the pump 3 requiring maintenance into the chamber space 4A through the pump barrel 2. The lifting device 5 also suspends the pump 3 after maintenance or a new pump 3 into the tank body 10 through the pump barrel 2. Furthermore, the lifting device 5 lifts and lowers the pump 3 through the pump inlet / outlet 45. 【0029】 The lifting device 5 includes a drum 51 that rotates forward and backward around an axis, and a lifting wire 52 wound around the drum 51. The lifting wire 52 is unwound when the drum 51 rotates forward, and the lifting wire 52 is wound back in when the drum 51 rotates backward. When lifting the pump 3, the lifting wire 52 is suspended through the barrel opening 2H into the barrel interior space 2A, and the end of the lifting wire 52 is connected to the pump 3. 【0030】 The lifting device 5 is installed so as to be movable vertically above the pump barrel 2 and vertically above the pump inlet / outlet 45. A hoist rail 53 extending horizontally is installed near the top wall 411 of the chamber body 41. The hoist rail 53 extends from above the barrel opening 2H to above the pump inlet / outlet 45 between the inner wall 412 and the outer wall 413 of the protrusion 41T. A movable roller 54 that holds the drum 51 is engaged with the hoist rail 53. This allows the drum 51 to move horizontally along the hoist rail 53 from above the barrel opening 2H to above the pump inlet / outlet 45. A temporary pump storage area 46 is also located along this movement path. 【0031】 The gas replacement device 6 is equipment that replaces the air environment in the chamber space 4A and the auxiliary chamber space 4B with a predetermined replacement gas environment. The replacement gas environment is at least the gas environment of the liquefied gas stored in the tank body 10, a hydrogen gas environment which is the vaporized gas of liquefied hydrogen LH in this embodiment, or an inert gas environment. Examples of inert gases include noble gases such as helium and nitrogen gas. 【0032】 The gas replacement device 6 includes a replacement gas supply source, an air supply pump, a flow control valve, etc. The main air supply pipe 61 of the gas replacement device 6 is connected to the inlet port 416 of the chamber body 41, and the air supply pipe 62 for the spare chamber is connected to the spare chamber inlet port 421. During maintenance of the pump 3, hydrogen gas or helium gas is supplied from the gas replacement device 6 to the chamber space 4A through the main air supply pipe 61. The air that was present in the chamber space 4A before the supply is discharged to the outside through the exhaust port 417. This prevents air from entering the barrel space 2A from the barrel opening 2H even when the head plate 25 of the pump barrel 2 is opened to lift the pump 3. 【0033】 Alternatively, nitrogen gas may be supplied to the chamber space 4A instead of helium gas. In this case, measures must be taken to prevent the nitrogen gas from entering the barrel space 2A. For example, pressure adjustment is performed to set the pressure in the chamber space 4A lower than the pressure in the barrel space 2A. The pressure difference resulting from this pressure adjustment prevents the nitrogen gas filling the chamber space 4A from entering the barrel space 2A. 【0034】 Furthermore, during maintenance, an inert gas such as nitrogen gas is supplied to the reserve chamber space 4B from the gas replacement device 6 through the reserve chamber air supply pipe 62. The air that was present in the reserve chamber space 4B before the supply is discharged to the outside through the reserve chamber exhaust port 422. This prevents air from entering the chamber space 4A even if the inner door 44 is opened and the airtightness of the chamber space 4A is released. Hydrogen gas or helium gas may be supplied to the reserve chamber space 4B instead of nitrogen gas. 【0035】 [Pump removal work] Next, we will briefly explain an example of the work performed in the chamber 4 when removing the pump 3 during maintenance work. First, the gas replacement device 6 is activated to supply the predetermined replacement gas, as described above, to the chamber space 4A and the auxiliary chamber space 4B. It is desirable to continuously supply the replacement gas during maintenance work to maintain ventilation of the chamber space 4A and the auxiliary chamber space 4B. When workers enter through the opening / closing door 43, they are equipped with oxygen cylinders. 【0036】 The worker removes the head plate 25 to open the barrel opening 2H and takes out the suspension wire 52 stored inside the pump barrel 2 near the head plate 25. One end of the suspension wire 52 is attached to the lifting device 5. The other end of the suspension wire 52 is already attached to the pump 3. The worker then operates the lifting device 5 to wind the suspension wire 52 onto the drum 51. As a result of this operation, the pump 3, which was installed at the lower end 21 of the pump barrel 2, is lifted through the barrel space 2A into the chamber space 4A. After that, the barrel opening 2H is closed with the head plate 25. 【0037】 Next, the worker operates the hoist drive device to move the drum 51, with the pump 3 suspended from it, along the hoist rail 53, positioning it above the temporary pump storage area 46. Then, the pump 3 is lowered and stored in the temporary pump storage area 46. After holding the pump 3 in the temporary pump storage area 46 for a predetermined purging time, the drum 51 is made to rewind the suspension wire 52, lifting the pump 3 again. Subsequently, the drum 51 is moved along the hoist rail 53 to above the pump loading / unloading outlet 45. 【0038】 Subsequently, the pump inlet / outlet 45 is opened. Then, the pump suspension wire 52 is unfurled from the drum 51, and the suspended pump 3 is lowered, and as shown by the dotted line in Figure 2, the pump 3 is transported outside the chamber body 41 through the pump inlet / outlet 45. Since the pump inlet / outlet 45 is opened in the protruding section 41T, the pump 3 can be brought into contact with the ground or the bed of a recovery vehicle simply by lowering it. Once the lowering is complete, the suspension wire 52 is removed from the pump 3, and the pump 3 is recovered. When installing a pump 3 after maintenance, or a new pump 3, inside the tank body 10, the reverse of the above procedure is performed. 【0039】 As described above, according to the liquefied gas tank 1 of this embodiment, the chamber space 4A of the chamber 4, which is installed to cover the barrel opening 2H, can be replaced by the gas replacement device 6 with a hydrogen gas environment or an inert gas environment corresponding to the stored liquefied hydrogen. Furthermore, the lifting device 5 lifts the pump 3 into the chamber space 4A through the pump barrel 2. As a result, the pump 3 inside the tank body 10 can be removed to the outside of the tank body 10 without the barrel opening 2H being exposed to air. Therefore, it is possible to prevent air present around the tank body 10 from mixing into the pump barrel 2. 【0040】 [Differentiation] Although embodiments of the present invention have been described above, the present invention is not limited to these, and for example, the following modified embodiments can be taken. 【0041】 (1) In order to simplify the chamber 4, the spare chamber 42 and the temporary pump storage area 46 may be omitted. Conversely, the spare chamber 42 may be configured in two stages, with one spare chamber used as a space for replacing air with nitrogen gas, and the other spare chamber, which is closer to the main chamber 41, used as a space for replacing nitrogen gas with hydrogen gas or helium gas. 【0042】 (2) In the above embodiment, an example was given in which the lifted pump 3 is moved along the hoist rail 53. Alternatively, a first lifting device for raising and lowering the pump 3 through the pump barrel 2 and a second lifting device for raising and lowering the pump 3 through the pump inlet / outlet 45 may be installed in the chamber body 41, and the movement of the pump 3 between the two devices may be carried out by a transport device such as a mobile cart or a transport robot. 【0043】 (3) In the above embodiment, an example was shown in which a protrusion 41T is provided on the chamber body 41, and a pump inlet / outlet 45 is opened in the bottom wall 414 of the protrusion 41T. Alternatively, instead of providing a protrusion 41T, an opening for the removal of the pump 3 may be provided in the radial side wall 415 or the top wall 411, and the pump 3 may be lowered to the ground using a crane installed outside. 【0044】 [Summary of this disclosure] The specific embodiments described above include disclosures having the following configurations. 【0045】 A liquefied gas tank according to a first aspect of the present disclosure comprises: a tank body for storing liquefied gas; a pump barrel penetrating the tank body vertically; a pump installed inside the tank body for discharging the liquefied gas stored inside the tank body through the pump barrel; a chamber installed outside the tank body so as to cover the barrel opening at the upper end of the pump barrel; a lifting device installed outside the tank body for lifting the pump into the chamber through the pump barrel; and a gas replacement device for replacing the chamber with at least the gas environment of the stored liquefied gas or an inert gas environment. 【0046】 This liquefied gas tank allows the inside of a chamber, which is installed to cover the barrel opening, to be replaced by a gas environment of the stored liquefied gas or an inert gas environment using a gas replacement device. Furthermore, a lifting device lifts the pump into the chamber through the pump barrel. Therefore, the pump inside the tank body can be removed to the outside of the tank body without the barrel opening being exposed to air. Consequently, the ingress of air present around the tank body into the pump barrel can be prevented. 【0047】 A liquefied gas tank according to a second embodiment is a liquefied gas tank according to a first embodiment, wherein the chamber includes a projection that protrudes radially outward from the outer circumference of the tank body, and the projection is provided with a pump inlet / outlet for transporting the pump from inside the chamber to the outside or from the outside into the chamber. 【0048】 According to the second embodiment, a pump lifted from inside the tank body can be removed from the chamber to the outside through the pump inlet / outlet, or a new pump or a pump after maintenance can be brought into the chamber from the outside. Furthermore, since the pump inlet / outlet is provided on a protruding part of the chamber, the pump can be brought in and out of the chamber using a simple lifting device. 【0049】 A liquefied gas tank according to a third embodiment further comprises a pump temporary storage section installed in the chamber and for temporarily holding the pump that has been suspended from the tank body, in addition to the liquefied gas tank according to the first or second embodiment. 【0050】 According to the third embodiment, the suspended pump can be temporarily held in the chamber by utilizing the temporary pump storage section. Therefore, for example, it becomes possible to purge any liquefied gas remaining in the pump while it is temporarily stored in the temporary pump storage section. 【0051】 A liquefied gas tank according to the fourth embodiment is a liquefied gas tank according to any of the first to third embodiments, wherein the chamber is installed on the roof of the tank body and has an inlet that allows access to the chamber from the central side wall of the tank body or from the radial side wall of the tank body. 【0052】 According to the fourth embodiment, an inlet is provided in the side wall on the central side of the tank body or in the side wall along the radial direction, so that workers can easily enter and exit the chamber from the roof of the tank body through the inlet. 【0053】 A liquefied gas tank according to the fifth embodiment further comprises a spare chamber installed between the inlet and the chamber in the liquefied gas tank of the fourth embodiment. 【0054】 According to the fifth embodiment, the presence of a spare chamber makes it difficult for the chamber's internal space and the atmosphere to communicate directly when the inlet is opened and closed. Therefore, it is easier to restrict the entry of air into the chamber. 【0055】 The liquefied gas tank according to the sixth embodiment is a liquefied gas tank according to the fifth embodiment, wherein the gas replacement device replaces the contents of the pre-chamber with at least an inert gas environment or an atmospheric environment. 【0056】 According to the sixth embodiment, for example, the preliminary chamber can be replaced with an inert gas environment in advance before the inlet is opened, thereby suppressing the inflow of air from the preliminary chamber into the chamber. [Explanation of symbols] 【0057】 LH Liquid Hydrogen (Liquefied Gas) 1. Liquefied gas tank 10 Tank body 2 pump barrels 2A Barrel interior space 2H barrel opening 3 pumps 4 chambers 4A Chamber space 4B Reserve interior space 41 Chamber body (chamber) 41T protrusion 412 Inner wall (side wall on the center side of the tank body) 42 Spare Room 43. Opening / closing door (entrance area) 44 Inner door 45 Pump Inlet / Outlet 46 Pump temporary storage area 5. Lifting device 6. Gas replacement device

Claims

[Claim 1] The tank body for storing liquefied gas, A pump barrel that penetrates the tank body in the vertical direction, A pump installed inside the tank body, which discharges the liquefied gas stored inside the tank body through the pump barrel, A chamber is installed outside the tank body so as to cover the barrel opening at the upper end of the pump barrel, A lifting device installed on the outside of the tank body, which lifts the pump into the chamber through the pump barrel, A gas replacement device that replaces the inside of the chamber with at least the gas environment of the stored liquefied gas or an inert gas environment, The lifting device provides a pump inlet / outlet for transporting the pump from inside the chamber to the outside or from the outside into the chamber, A liquefied gas tank equipped with [a specific feature / feature]. [Claim 2] In the liquefied gas tank according to claim 1, The chamber includes a protrusion that extends radially outward from the outer circumference of the tank body, The aforementioned protrusion is a liquefied gas tank equipped with the pump inlet and outlet. [Claim 3] In the liquefied gas tank according to claim 1, A liquefied gas tank further comprising a pump temporary storage section installed within the chamber, for temporarily holding the pump that has been suspended from the tank body. [Claim 4] In the liquefied gas tank according to any one of claims 1 to 3, The chamber is installed on the roof of the tank body, A liquefied gas tank having an inlet that allows access to the chamber from the central side wall of the tank body or from the radial side wall of the tank body in the chamber. [Claim 5] In the liquefied gas tank according to claim 4, A liquefied gas tank further comprising a spare chamber installed between the inlet and the chamber. [Claim 6] In the liquefied gas tank according to claim 5, The gas replacement device is a liquefied gas tank that replaces the contents of the pre-chamber with at least an inert gas environment or an atmospheric environment. [Claim 7] A tank body for storing liquefied hydrogen, A pump barrel that penetrates the tank body in the vertical direction, A pump installed inside the tank body, which discharges the liquefied hydrogen stored inside the tank body through the pump barrel, A chamber is installed outside the tank body so as to cover the barrel opening at the upper end of the pump barrel, A lifting device installed on the outside of the tank body, which lifts the pump into the chamber through the pump barrel, A gas replacement device for replacing the environment inside the chamber with a nitrogen gas environment, A pressure adjustment mechanism that sets the pressure inside the chamber of the chamber to be less than the pressure inside the barrel of the pump barrel, A liquefied gas tank equipped with [a specific feature / feature].

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