Cryogenic tank pumping equipment

Abstract

To provide a liquid lifting device for a low-temperature tank that can reliably prevent storage liquid from flowing into a pump column when a submerged pump that is stored in the pump column is pulled out and maintained.SOLUTION: In a liquid lifting device for a low-temperature tank 1 that opens a foot valve 6 downward with the weight of a submerged pump 4 when the submerged pump 4 is lowered downward and closes a foot valve 6 with the force of a spring 17 when the submerged pump 4 is lifted upward, a pressurized gas 22 is supplied to an internal space 21 of a cylinder 15 through pressurizing piping 14 while the foot valve 6 is closed.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a liquid pumping device for use in a cryogenic tank. [Background technology]

[0002] A cryogenic tank for storing a cryogenic liquid such as ammonia is equipped with a liquid pumping device for discharging the stored liquid.

[0003] The liquid pumping device is composed of a cylindrical pump column having openings above the roof and near the bottom of the cryogenic tank, and a submerged pump that pumps out the liquid stored in the cryogenic tank housed within the pump column. A head plate is provided at the top of the pump column, and a support cable extending from the head plate is connected to the submerged pump. This support cable allows the submerged pump to be lowered within the pump column and raised and lowered by winding it up. A foot valve that opens and closes as the submerged pump rises and falls is provided at the bottom of the pump column, and a foot valve adapter is connected to support the foot valve in a state that allows it to be opened and closed. When the support cable connected to the submerged pump is reeled down and the submerged pump is lowered to its seat in the foot valve adapter, the tip of the submerged pump rests on the protrusion at the top of the foot valve, causing the foot valve to open against the force of the spring above it, opening the liquid suction port at the bottom of the foot valve adapter and allowing the stored liquid to flow into the pump column, enabling the submerged pump to pump liquid. After pumping is complete, the support cable connected to the submerged pump is reeled up and removed from its seat in the pump column. The foot valve closes under the force of the spring, acting as a check valve and closing the liquid suction port, preventing the stored liquid from flowing into the pump column.

[0004] When the submerged pump is removed from the pump column for maintenance, the pump column is first purged with pressurized gas such as N2 gas while the liquid suction port to the pump column is closed with a foot valve to prevent vaporized gas from the stored liquid remaining in the pump column from leaking out of the tank. Purging with N2 gas involves sealing N2 gas into the pump column through purge piping connected to the pump column, and then forcibly opening the foot valve using the pressure of the N2 gas, discharging the stored liquid remaining in the pump column into the cryogenic tank. When the pump column is filled with N2 gas and you can hear the sound of N2 gas being discharged into the cryogenic tank, stop filling the N2 gas and release the pressure in the pump column.

[0005] Next, the head plate closing the upper opening of the pump column is removed, and the lift cable hanging from the head plate is connected to a hoist or other hoisting device, and the hoisting device is operated to pull out the submerged pump hanging from the lift cable from inside the pump column. When performing maintenance on the submerged pump, the pump column should be purged with N2 gas to prevent vaporized gas from the liquid stored in the tank from leaking outside the cryogenic tank. In particular, when ammonia is stored in a cryogenic tank, care must be taken to prevent ammonia from leaking outside the tank during maintenance, as ammonia is lighter than air, flammable, and toxic.

[0006] Maintenance of submerged pumps is performed with the liquid suction port of the foot valve adapter attached to the bottom of the pump column closed with a foot valve, but if the foot valve is not completely closed, the liquid stored in the cryogenic tank will flow into the pump column through the gap between the bottom end face of the foot valve adapter and the top end face of the foot valve, and when the head plate is opened, the vaporized gas from the stored liquid that has flowed into the pump column will leak out of the cryogenic tank.

[0007] Preventing leakage of vaporized gas from the liquid stored in the cryogenic tank when performing maintenance on such a submerged pump is an issue, and a structure for a cryogenic tank liquid pumping device that solves this issue is required.

[0008] Conventional techniques for devices for pumping liquid from low-temperature tanks have been disclosed (Patent Documents 1 and 2).

[0009] Patent Document 1 discloses a pumping device for a cryogenic liquid storage tank, in which a foot valve is attached to the lower end opening of a pump barrel inserted vertically into the storage tank, a fluid pressure actuator is attached to the lower edge of the pump barrel, and the movable part of this fluid pressure actuator and the foot valve are connected by a spindle.

[0010] Patent Document 2 discloses a liquid pumping device for a cryogenic liquid storage tank, which comprises a foot valve attached to the lower opening of a pump barrel inserted vertically into the storage tank, a spring attached to the lower edge of the pump barrel, the spring and the foot valve connected by a spindle, and a fluid pressure actuator attached to the lower edge of the pump barrel, and the movable part of the fluid pressure actuator and the foot valve connected by a spindle so that the fluid pressure actuator can operate the foot valve in the closing direction.

[0011] The prior art described in Patent Documents 1 and 2 is a pumping device for a cryogenic liquid storage tank in which fluid pressure actuated devices and springs are alternately arranged on the concentric circumference of the lower edge of a pump column, and fluid is supplied to the fluid pressure actuated device to close a foot valve. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] Japanese Utility Model Application Publication No. 59-183598 [Patent Document 2] Japanese Utility Model Application Publication No. 59-183599 Summary of the Invention [Problem to be solved by the invention]

[0013] In conventional submerged pumps for cryogenic tanks, the force of the spring attached to the bottom of the foot valve adapter at the bottom of the pump column is insufficient to close the foot valve, causing the stored liquid in the cryogenic tank to flow into the pump column through the liquid suction port of the foot valve adapter, and causing vaporized gas from the stored liquid to leak out of the tank when the head plate at the top of the pump column is opened.

[0014] The present invention has been made in consideration of the above circumstances and provides a liquid pumping device for a cryogenic tank, in which a cylinder is attached to the bottom of a foot valve adapter part attached to the bottom of a pump column, and a shaft member and spring connected to the foot valve are provided inside the cylinder, and when the foot valve is closed, pressurized gas is supplied into the cylinder to apply additional force in the direction of closing the foot valve, thereby reliably preventing stored liquid from flowing into the pump column. [Means for solving the problem]

[0015] The present invention provides a cylindrical pump column erected by penetrating the roof of the cryogenic tank; a head plate that closes an upper opening of the pump column; a submerged pump housed in the pump column so as to be able to move up and down; a foot valve disposed between the submerged pump and the bottom of the inner shell of the cryogenic tank, the foot valve being opened and closed by the rise and fall of the submerged pump; a foot valve adapter portion connected to a lower portion of the pump column and supporting the foot valve in a state in which the foot valve can be opened and closed; and the foot valve adapter portion having a lower edge portion that contacts the foot valve, a cylinder attached to a lower portion of the foot valve adapter; a shaft member having a first end and a second end, the first end being widened to form a piston shape, the foot valve being connected to the opposite second end, and the first end being slidably disposed within the cylinder; a spring provided between an upper wall surface of the cylinder and the first end of the shaft member; a pressurizing pipe for supplying pressurized gas to a space between the first end of the shaft member and a bottom surface of the cylinder inside the cylinder, In the liquid pumping device for a cryogenic tank, when the submerged pump is lowered, the weight of the submerged pump opens the foot valve downward, and when the submerged pump is raised, the force of the spring closes the foot valve, The liquid pumping device for a cryogenic tank supplies the pressurized gas to the space inside the cylinder through the pressurizing piping while the foot valve is closed, thereby applying further force in the direction of closing the foot valve.

[0016] The present invention also provides The cryogenic tank pumping device is provided such that the pressurizing pipe is connected to the cylinder and supplies the pressurized gas into the space inside the cylinder.

[0017] Furthermore, the present invention provides a bellows in the space inside the cylinder; The pressurizing pipe is connected to the bellows, and the pressurized gas is supplied into the bellows.

[0018] Furthermore, the present invention provides A hollow bag having a doughnut shape is provided in the space of the cylinder, The liquid pumping device for a cryogenic tank is provided, in which the pressurizing pipe is connected to the bag body and the pressurized gas is supplied into the bag body.

[0019] Furthermore, the present invention provides The pressurized gas supplied by the pressurizing pipe is The gas is the same type as the pressurized gas used to purge the pump column. A liquid lifting device for the cryogenic tank is provided. [Effects of the Invention]

[0020] The present invention provides a liquid pumping device for a cryogenic tank that can reliably prevent stored liquid from flowing into a pump column when a submerged pump housed in the pump column is pulled out for maintenance. [Brief explanation of the drawings]

[0021] [Figure 1] 1 shows a vertical cross section of a cryogenic tank pumping device according to an embodiment of the present invention. [Figure 2] 1 shows the detailed structure of a submerged pump and a foot valve that constitute the cryogenic tank pumping device according to the present invention. [Figure 3] 1 shows a detailed structure of a first example of a cylinder according to the present invention. [Figure 4] 1 shows a detailed structure of a second example of a cylinder according to the present invention. [Figure 5] 10 shows a detailed structure of a third example of a cylinder according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0022] An embodiment of a cryogenic tank liquid pumping device according to the present invention will be described with reference to Figures 1 to 5. The present invention is not limited to the following embodiment. Of course, the following components can be omitted or added, and modifications to the embodiment, such as the shape of the components, can be made without departing from the spirit of the present invention. Note that the figures are schematic, depicting only a portion and omitting the detailed structure.

[0023] 1 is a longitudinal cross-sectional view of one embodiment of a cryogenic tank according to the present invention. The cryogenic tank 1 has an inner shell 2 forming an inner tank for storing a storage liquid 9, an outer shell 3 surrounding the inner shell 2 at a distance and forming an outer tank, and a heat insulating material 11 in the space between the inner shell 2 and the outer shell 3. As shown in FIG. 1, the low-temperature tank 1 has an inner shell bottom 2a mounted on a concrete foundation 12 with a bottom insulating material 11a such as perlite concrete interposed therebetween, an inner shell side 2b erected on the inner shell bottom 2a, and an inner shell roof 2c mounted on the inner shell side 2b. The outer shell bottom portion 3a is laid on a foundation 12. A PC outer shell side portion 3b serving as a liquid barrier is erected on the outer shell bottom portion 3a, outside the bottom insulation material 11a, and an outer shell roof portion 3c is provided on the outer shell side portion 3b. A seal metal 13 is attached to the inner peripheral surface of the outer shell side portion 3b, and the peripheral edge of the outer shell roof portion 3c is fixed to the upper end of the outer shell side portion 3b. Side insulation material 11b is filled between the inner shell side portion 2b and the outer shell side portion 3b. Furthermore, roof insulation material 11c is filled between the inner shell roof portion 2c and the outer shell roof portion 3c. The roof shapes of the inner shell roof portion 2c and the outer shell roof portion 3c can both be hemispherical or partially spherical. The cryogenic tank 1 may have not only a flat-bottomed cylindrical shape as shown in FIG. 1, but also a vertically placed cylindrical shape, a horizontally placed cylindrical shape, a spherical shape, or the like.

[0024] The liquid 9 stored in the low-temperature tank 1 is, for example, liquid ammonia, liquid hydrogen, or the like. Each of the components constituting the cryogenic tank 1, such as the inner shell 2 and outer shell 3, can be made of a material that is resistant to the storage liquid 9 stored in the cryogenic tank 1. For example, steel for cryogenic pressure vessels, stainless steel, aluminum alloy, etc.

[0025] The liquid pumping device for the cryogenic tank 1 comprises a cylindrical pump column 5 that is erected by penetrating the inner shell roof portion 2c and the outer shell roof portion 3c, a head plate 8 that closes the upper opening 5a of the pump column 5, a submerged pump 4 that is connected to the head plate 8 via a support cable 7 and is housed in the pump column 5 so that it can be raised and lowered, a foot valve 6 that is located between the submerged pump 4 and the inner shell bottom portion 2a of the cryogenic tank 1 and opens and closes when the submerged pump 4 is lowered and raised, and a foot valve adapter portion 27 that is connected to the bottom of the pump column 5 and supports the foot valve 6 in a state that allows it to be opened and closed. Here, the foot valve adaptor part 27 has a lower edge part that contacts the foot valve 6, and comprises a cylinder 15 attached to the lower part of the foot valve adaptor part 27, a shaft member 16 whose first end 16a is widened to provide a piston-like part and whose opposite second end 16b is connected to the foot valve 6, and whose first end 16a is arranged so that it can slide within the cylinder 15, and a spring 17 provided between the upper wall surface of the cylinder 15 and the upper end surface of the first end 16a of the shaft member 16. When the submerged pump 4 is lowered, the weight of the submerged pump 4 opens the foot valve 6 downward, and when the submerged pump 4 is raised, the foot valve 6 closes due to the force of the spring 17. Figure 1 shows the foot valve 6 in an open state. The upper flange 33 of the pump column 5 and the head plate 8 are fastened together with a plurality of flange mounting bolts 31 and a plurality of flange mounting nuts 32 .

[0026] The liquid pumping device for the cryogenic tank 1 includes a pressurizing pipe 14 that supplies pressurized gas 22 to a space 21 between the first end 16a of the shaft member 16 and the bottom of the cylinder 15 inside the cylinder 15, and a purge pipe 20 that is connected to the pump column 5 and introduces pressurized gas into the pump column 5, forcing the stored liquid 9 back into the cryogenic tank 1 and purging it. The pressurized gas supplied through the pressurizing pipe 14 and the purge pipe 20 may be N2 gas.

[0027] The submerged pump 4 is connected to a support cable 7 wound down from a head plate 8 that liquid-tightly closes the upper opening 5a of the pump column 5, and when the submerged pump 4 is lowered or raised within the pump column 5, the submerged pump 4 is suspended and supported via the support cable 7. A lift shaft 23 is also disposed passing through the head plate 8. The lift shaft 23 is lowered or raised when the submerged pump 4 is lowered or raised, and supports the submerged pump 4 via the support cable 7. A connecting member 23a is provided at the top of the lift shaft 23 to which a lift cable (not shown) from a lift (not shown) is connected. The support cable 7 suspends and supports the submerged pump 4 when the submerged pump 4 is raised or lowered within the pump column 5. The support cable 7 is made of a metal wire or the like. The support cable 7 is connected to the lift shaft 23 and the connecting member 4b at the top of the submerged pump 4.

[0028] Figure 2 shows the detailed structure of the submerged pump and foot valve that constitute the cryogenic tank pumping device of the present invention. (a) shows the foot valve in an open state, and (b) shows the foot valve in a closed state. A protrusion 35 is attached to the upper end surface 6a of the foot valve 6, and when the submerged pump 4 is pushed all the way down, the tip 4a of the submerged pump 4 comes into contact with the protrusion 35 of the foot valve 6, and the weight of the submerged pump 4 pushes the foot valve 6 down, opening it. A gap is created between the upper end surface 6a of the foot valve 6 and the lower end surface 30a of the lower flange part 30 of the foot valve adaptor part 27, and the stored liquid 9 in the cryogenic tank 1 is sucked into the pump column 5 through the lower opening 27b of the foot valve adaptor part 27. When the submerged pump 4 in the cryogenic tank 1 is driven, the stored liquid 9 sucked into the pump column 5 is pushed up to the top of the pump column 5 by the submerged pump 4 and is discharged from the discharge piping 10 at the top of the pump column 5.

[0029] The foot valve adapter portion 27 connected to the lower portion of the pump column 5 is composed of an upper flange portion 28 , a cylindrical portion 29 , and a lower flange portion 30 . The lower flange 34 of the pump column 5 and the upper flange portion 28 of the foot valve adapter portion 27 are fastened together by a plurality of flange mounting bolts 31 and a plurality of flange mounting nuts 32 . The lower opening 27b of the foot valve adaptor 27 serves as a liquid suction port for the stored liquid 9 into the pump column 5 when the foot valve 6 is open.

[0030] As shown in FIG. 2(a), the submerged pump 4 is lowered by winding down the support cable 7, and the foot valve 6 opens under the weight of the submerged pump 4. Also, as shown in (b), by winding up the support cable 7, the submerged pump 4 rises and the foot valve 6 can be closed. The strength of the spring 17 in the cylinder 15 provided in the lower flange portion 30 at the bottom of the foot valve adapter portion 27 is adjusted so that the foot valve 6 opens under the weight of the submerged pump 4 itself.

[0031] When the submerged pump 4 is pulled out from inside the pump column 5 for inspection, the operation of the submerged pump 4 is stopped. A cable (not shown) from a lift (not shown) is connected to the connecting member 23a of the lift shaft 23, and when the lift shaft 23 is raised by the lift, the submerged pump 4 rises via the support cable 7 connected to the lift shaft 23, and the foot valve 6 is released from the gravity of the submerged pump 4 and is closed by the force of the spring 17. The position of the lift shaft 23 is fixed in the raised position by a spacer (not shown). At this time, pressurized gas is purged into the pump column 5 through the purge piping 20. Next, pressurized gas 22 is supplied into cylinder 15 through pressurizing piping 14 to pressurize it, and the lower opening 27b of foot valve adapter part 27 attached to the bottom of pump column 5 is securely closed with foot valve 6, reliably preventing stored liquid 9 in cryogenic tank 1 from flowing into pump column 5 and vaporized gas of stored liquid 9 from leaking out of cryogenic tank 1. Next, the head plate 8 is removed from the top of the pump column 5, the support cable 7 connected to the head plate 8 is removed, and the lift cable (not shown) hanging from the head plate 8 is wound around a hoist or other hoisting device (not shown), and the hoisting device is operated to pull out the submerged pump 4 from inside the pump column 5.

[0032] A ring-shaped seal member 24 is attached to the lower flange portion 30 of the foot valve adapter portion 27 attached to the bottom of the pump column 5. When the foot valve 6 is closed, this seal member 24 seals the gap between the lower end surface 30a of the lower flange portion 30 and the upper end surface 6a of the foot valve 6. This seal member 24 is made of PTFE or the like. This seal member 24 is disposed in a seal groove 25 provided in the lower flange portion 30. When the submerged pump 4 is raised and the foot valve 6 rises in conjunction with the movement of the submerged pump 4, if the surface contact between the lower end surface 30a of the lower flange portion 30 and the upper end surface 6a of the foot valve 6 is uneven, the foot valve 6 will not completely close the lower opening 27b of the foot valve adapter portion 27, causing stored liquid 9 such as ammonia to flow from inside the cryogenic tank 1 into the pump column 5 and causing the vaporized gas of the stored liquid 9 to leak out of the cryogenic tank 1. Therefore, pressurized gas 22 is supplied into the cylinder 15 attached to the lower flange portion 30 below the foot valve adapter portion 27, pressurizing the foot valve 6 in the direction of closing it. This makes the surface contact between the lower end surface 30a of the lower flange portion 30 and the upper end surface 6a of the foot valve 6 stronger and more uniform, eliminating any gaps and completely preventing the stored liquid 9 from flowing into the pump column 5.

[0033] FIG. 3 shows the detailed structure of a first example of a cylinder according to the present invention. A plurality of cylinders 15 are provided at equal intervals on a concentric circle on the lower flange portion 30 at the bottom of the foot valve adapter portion 27 attached to the bottom of the pump column 5, and a pressurizing pipe 14 is attached to each cylinder 15. The shaft member 16 connected to the foot valve 6 has a first end 16a and a second end 16b, the first end 16a being widened to form a cylindrical portion, the foot valve 6 being connected to the opposite second end 16b, and the first end 16a being slidably arranged inside the cylinder 15. The shaft member 16 is inserted and slid through the insertion hole 30b of the lower flange portion 30 of the foot valve adapter portion 27 and the insertion hole 15b at the bottom of the cylinder 15, and can be raised and lowered in conjunction with the raising and lowering of the foot valve 6. In addition, a spring 17 is provided between the upper wall surface of the cylinder 15 and the upper end surface of the piston-shaped portion of the first end 16 a of the shaft member 16 . Furthermore, inside the cylinder 15, a space 21 is formed below the lower end surface of the piston-shaped portion of the first end 16a of the shaft member 16. The pressurizing pipe 14 is connected to an insertion hole 15 a provided in the cylinder 15 , and supplies pressurized gas 22 into a space 21 within the cylinder 15 . When the foot valve 6 is open as shown in (a), the submerged pump 4 is lowered and the foot valve 6 is pushed open by the weight of the submerged pump 4. At this time, the space 21 in the cylinder 15 is not filled with pressurized gas 22, and the spring 17 is extended by the amount pushed down by the weight of the submerged pump 4. When the foot valve 6 is closed in (b), the submerged pump 4 is raised, the foot valve 6 is released from the weight of the submerged pump 4, and the foot valve 6 is closed. As in (a), the space 21 in the cylinder 15 is not filled with pressurized gas 22, the spring 17 is released from the weight of the submerged pump 4, and due to its restoring force, it becomes shorter than when the foot valve 6 is open in (a). At the stage (c) after purging the interior of the pump column 5 with pressurized gas has been completed and before the head plate 8 is removed and the pump column 5 is opened (hereinafter referred to as time shut), pressurized gas 22 is supplied from the pressurizing pipe 14 to the space 21 within the cylinder 15, and further force is applied in the direction of closing the foot valve 6 connected to the shaft member 16, so that the lower opening 27b of the foot valve adapter part 27, which serves as the liquid suction port for the stored liquid 9 into the pump column 5, is securely closed by the foot valve 6.

[0034] FIG. 4 shows the detailed structure of a second example of a cylinder according to the present invention. The description of the same structure as in FIG. 3 will be omitted. A bellows 18 is placed in a space 21 inside the cylinder 15, and the pressurizing pipe 14 is connected to the bellows 18 to supply pressurized gas 22 into the bellows 18. The bellows 18 is made of a material that can be expanded by supplying pressurized gas 22, and is made of, for example, metal or resin. When the foot valve 6 is open as shown in (a), the submerged pump 4 is lowered and the foot valve 6 is pushed open by the weight of the submerged pump 4. At this time, the bellows 18 in the space 21 inside the cylinder 15 is not filled with pressurized gas 22, the bellows 18 is in a contracted state, and the spring 17 extends by the amount that the submerged pump 4 is pushed down by its own weight. When the foot valve 6 is closed as shown in (b), the submerged pump 4 is raised, the foot valve 6 is released from its own weight, and the foot valve 6 is closed. At this time, the bellows 18 in the space 21 inside the cylinder 15 is not filled with pressurized gas 22, the spring 17 is released from the own weight of the submerged pump 4, and due to its restoring force, it becomes shorter than when the foot valve 6 is open as shown in (a). In the time shut (c), pressurized gas 22 is supplied into the bellows 18 in the space 21 inside the cylinder 15 to expand the bellows 18, thereby applying further force in the direction of closing the foot valve 6 connected to the shaft member 16, and the foot valve 6 securely closes the lower opening 27b of the foot valve adapter part 27, which serves as the liquid suction port for the stored liquid 9 into the pump column 5.

[0035] The shaft member 26 in Figure 4 has a first end 26a with three or more insertion holes 26e formed on a concentric circumference, and three or more rod-shaped members 26c that are inserted into each of the insertion holes 26e in the first end 26a and have their second ends 26b connected to the foot valve 6, and the position of the first end 26a is fixed by fixing the top and bottom of the insertion holes 26e of each of the rod-shaped members 26c in the first end 26a with nuts 26d. The first end 26a is configured with a flange or the like, and is provided with three or more insertion holes 26e. The first end 26a of the shaft member 26 is widened to form a cylinder, and the foot valve 6 is connected to each of the second ends 26b on the opposite side, and the first end 26a is slidably arranged inside the cylinder 15. Each shaft-shaped member 26c is inserted and slid into each insertion hole 30b of the lower flange portion 30 of the foot valve adapter portion 27 and each insertion hole 15b of the bottom of the cylinder 15, and can be raised and lowered in conjunction with the raising and lowering of the foot valve 6. In addition, a spring 17 is provided between the upper wall surface of the cylinder 15 and the upper end of the piston-shaped portion of the first end 26 a of the shaft member 26 . Furthermore, inside the cylinder 15, a space 21 is formed below the lower end surface of the piston-shaped portion of the first end 26a of the shaft member 26, and the bellows 18 is located in the space 21. Bellows 18 is located radially inward of each of rod-shaped members 26c and is surrounded by three or more rod-shaped members 26c, so there is no misalignment of bellows 18. In addition, there is no need to provide an insertion hole in the center of bellows 18 for inserting rod-shaped members 26c of shaft member 26 therethrough.

[0036] FIG. 5 shows the detailed structure of a third example of a cylinder according to the present invention. The description of the same structures as those in FIGS. 3 and 4 will be omitted. A doughnut-shaped hollow bag 19 is placed in a space 21 inside the cylinder 15, and the pressurizing pipe 14 is connected to the bag 19 to supply pressurized gas 22 into the bag 19. The bag 19 has a central hole 19a through which the rod-shaped member 16c of the shaft member 16 is inserted. The bag 19 is made of a material that can expand when pressurized gas 22 is supplied, and is made of, for example, rubber or rubber containing a wire mesh. When the foot valve 6 is open as shown in (a), the submerged pump 4 is lowered and the foot valve 6 is pushed open by the weight of the submerged pump 4. At this time, the bag 19 in the space 21 inside the cylinder 15 is not filled with pressurized gas 22, the bag 19 is deflated, and the spring 17 extends by the amount pushed down by the weight of the submerged pump 4. When the foot valve 6 is closed as shown in (b), the submerged pump 4 is raised, the foot valve 6 is released from its own weight, and the foot valve 6 is closed. At this time, the bag 19 in the space 21 inside the cylinder 15 is not filled with pressurized gas 22, the spring 17 is released from the own weight of the submerged pump 4, and due to its restoring force, it becomes shorter than when the foot valve 6 is open as shown in (a). In the time shut (c), pressurized gas 22 is supplied into the bag body 19 in the space 21 inside the cylinder 15, causing it to expand, thereby applying further force in the direction of closing the foot valve 6 connected to the shaft member 16, and the lower opening 27b of the foot valve adapter part 27, which serves as the liquid suction port for the stored liquid 9 into the pump column 5, is securely closed by the foot valve 6.

[0037] The length of the cylinder 15 must be at least longer than the natural length of the spring 17, and must be long enough that when the foot valve 6 is pushed down and opened by the weight of the submerged pump 4, the spring 17 can expand by the amount that the foot valve 6 is pushed down. Furthermore, when the foot valve 6 is closed, it is necessary to provide a space 21 that can be pressurized with pressurized gas 22 from below the first end 16a of the shaft member 16 inside the cylinder 15 to the bottom of the cylinder 15, or a space 21 in which a pressurizing member such as a bellows 18 or a bag body 19 can be provided. The inner diameter of the cylinder 15 is set to a size that allows the first end 16a of the shaft member 16 of the foot valve 6 to not interfere with the inner wall surface of the cylinder 15, allows the shaft member 16 to move up and down without any hindrance, and leaves a slight gap between the inner wall side of the cylinder 15 and the outer edge of the piston-shaped portion of the first end 16a of the shaft member 16. The spring 17 has a force that allows the foot valve 6 to be opened by the weight of the submerged pump 4, and closes the foot valve 6 by the force of the spring 17 when it is released from the weight of the submerged pump 4. The spring 17 can be housed inside the cylinder 15, and its outer diameter is sized so as not to interfere with the inner wall surface of the cylinder 16.

[0038] Although one embodiment of the present invention has been described above, the present invention is not limited to this embodiment, and various modifications and changes are possible based on the technical concept of the present invention. For example, the pressurized gas supplied through the pressurizing pipe 14 and the purge pipe 20 according to the present invention is not limited to N2 gas, but other types of gases may also be used. Furthermore, the pressurized gases supplied through the pressurizing pipe 14 and the purge pipe 20 are not limited to the same type, but may be different types.

[0039] The cryogenic tank pumping device according to each embodiment of the present invention has at least one of the following effects. A shaft member connected to the foot valve, a spring, and space are provided inside the cylinder, integrating the structure that closes the foot valve with the structure that applies the closing force.When the submerged pump is raised, the foot valve is closed by spring force, and by supplying pressurized gas into the space within the cylinder, further force can be applied in the direction of pushing up the foot valve, and the synergistic effect of the spring force and gas pressure can be used to reliably close the foot valve. When an integrated structure is used in which the shaft member connected to the foot valve, the spring, and the bellows or bag are incorporated inside the cylinder, the position of the bellows or bag can be maintained by the cylinder, and pressurized gas can be supplied into the bellows or bag to stretch or expand it, so that further force can be applied in the direction of closing the foot valve and the foot valve can be closed reliably without having to consider the airtightness of the cylinder. Furthermore, by providing a space, bellows, or bag below the spring inside the cylinder, pressurized gas is supplied into the space, bellows, or bag rather than the entire cylinder when closing the foot valve, thereby achieving the effect of quickly increasing the closing force of the foot valve with a smaller gas pressure than before. During maintenance of the submerged pump, by supplying into the cylinder a gas pressure that overcomes the pressure of the gas that purges the inside of the pump column, the head plate at the top of the pump column can be removed with the foot valve securely closed, thereby preventing stored liquid such as ammonia from flowing into the pump column and reliably preventing vaporized gas of the stored liquid from leaking out of the tank from the upper opening of the pump column. The present invention can be easily implemented by simply adding a cylinder below the foot valve adapter attached to the bottom of the pump column and simple equipment such as pressurization piping to supply pressurized gas to the space within the cylinder or to the bellows or bag. Furthermore, since the present invention can be implemented by adding a process for pressurizing the inside of the cylinder to the maintenance of conventional submerged pumps, it can be implemented without significantly changing the way conventional submerged pumps are used. Furthermore, by using the same type of gas as the pressurized gas used to purge the inside of the pump column as the pressurized gas used to pressurize the inside of the cylinder, this can be easily implemented without the need to prepare a separate gas for pressurization.

[0040] The present invention is not limited to the above-described embodiment, and various modifications to the configuration are possible without departing from the spirit of the present invention. [Explanation of symbols]

[0041] 1. Cryogenic tank 2 Inner shell 2a Inner shell bottom 2b Inner shell side 2c Inner shell roof 3. Outer shell 3a Bottom of outer shell 3b Outer shell side 3c Outer shell roof section 4 Submerged Pump 4a Tip 4b Connecting member 5 Pump column 5a Top opening 5b Lower opening 6 Foot valve 6a Top end surface 7 Support Cable 8 Head Plate 9 Stock Solution 10 Discharge piping 11. Insulation 11a Bottom insulation 11b Side insulation 11c Roof insulation 12 Basics 13 Seal metal 14 Pressurizing piping 15 cylinders 15a Insertion hole 15b Insertion hole 16 Shaft member 16a First end (cylindrical portion) 16b 2nd end 16c Rod-shaped member 17 Spring 18 Bellow 19 Bag body 19a Center hole 20 Purge piping 21 Space 22 Pressurized Gas 23 Lift shaft 23a Connecting member 24 Sealing material 25 Seal groove 26 Shaft member 26a First end (cylindrical portion) 26b 2nd end 26c Rod-shaped member 26d Nut 26e Insertion hole 27 Foot valve adapter 27a Top opening 27b Lower opening (liquid inlet) 28 (Foot valve adapter part 27) upper flange part 29 Cylinder part 30 Lower flange portion (of foot valve adapter portion 27) 30a Bottom end surface 30b Insertion hole 31 Flange mounting bolt 32 Flange mounting nut 33 (Pump column 5) upper flange 34 Lower flange (of pump column 5) 35 Protrusion

Claims

1. a cylindrical pump column erected by penetrating the roof of the cryogenic tank; a head plate that closes an upper opening of the pump column; a submerged pump housed in the pump column so as to be able to move up and down; a foot valve disposed between the submerged pump and the bottom of the inner shell of the cryogenic tank, the foot valve being opened and closed by the rise and fall of the submerged pump; a foot valve adapter portion connected to a lower portion of the pump column and supporting the foot valve in a state in which the foot valve can be opened and closed; and the foot valve adapter portion having a lower edge portion that contacts the foot valve, a cylinder attached to a lower portion of the foot valve adapter; a shaft member having a first end and a second end, the first end being widened to form a piston shape, the foot valve being connected to the opposite second end, and the first end being slidably disposed within the cylinder; a spring provided between an upper wall surface of the cylinder and the first end of the shaft member; a pressurizing pipe for supplying pressurized gas to a space between the first end of the shaft member and a bottom surface of the cylinder inside the cylinder, In the liquid pumping device for a cryogenic tank, when the submerged pump is lowered, the weight of the submerged pump opens the foot valve downward, and when the submerged pump is raised, the force of the spring closes the foot valve, A liquid pumping device for a cryogenic tank, wherein, with the foot valve closed, the pressurized gas is supplied to the space inside the cylinder through the pressurizing piping, thereby applying further force in the direction of closing the foot valve.

2. 2. The cryogenic tank pumping device according to claim 1, wherein the pressurizing pipe is connected to the cylinder and supplies the pressurized gas into the space inside the cylinder.

3. a bellows in the space inside the cylinder; 2. The liquid pumping device for a cryogenic tank according to claim 1, wherein the pressurizing pipe is connected to the bellows and supplies the pressurized gas into the bellows.

4. A hollow bag having a doughnut shape is provided in the space of the cylinder, The liquid pumping device for a cryogenic tank according to claim 1 , wherein the pressurizing pipe is connected to the bag body and supplies the pressurized gas into the bag body.

5. The pressurized gas supplied by the pressurizing pipe is The gas is the same type as the pressurized gas used to purge the pump column.

5. The liquid pumping device for a cryogenic tank according to claim 1.

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