Foot valve assembly and submerged pump system

Abstract

To improve sealability of a foot valve assembly of a sub-merged pump system.SOLUTION: Foot valve assemblies 6, 6A respectively have: cylindrical adapters 10, 10A, each of which is fitted to a lower opening end 2b of a cylindrical pump column 2 where a pump 5 immersed in a handled liquid Lg is housed, and in which an intake port 5a of a pump is housed; disk-like valve bodies 20, 20A, each of which has a flow passage formation surface 21 located below a lower end surface 10a of the adapter to form an inflow passage FL for letting the handled liquid flow toward the pump with the lower end surface, and opens and closes a lower opening 11a of the adapter; an energizing member 62 which energizes the valve body toward the adapter; and a one-way valve 50 which is arranged in the inflow passage, and is opened according to the pressure of a fluid with respect to the fluid discharged from the lower opening and is closed with respect to the handled liquid flowing toward the lower opening, when the valve bodies are closed.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a foot valve assembly and a submerged pump system. [Background technology]

[0002] Submerged pumping systems are used to extract liquefied gas (such as liquefied natural gas or liquefied ammonia) from storage tanks. The pump (submerged pump) is housed in a pump column that extends from the ceiling of the storage tank into the liquefied gas and is submerged in the liquefied gas. The lower open end of the pump column is opened and closed by a foot valve assembly.

[0003] In a submerged pump system, the pump is removed from the storage tank, for example, for maintenance. When the pump is stopped, the pump column is filled with residual liquefied gas and vaporized liquefied gas (vaporized gas). If the head plate is removed in this state, the liquefied gas and vaporized gas (hereinafter collectively referred to as "residual gas") will leak to the outside. Since most residual gases are flammable and toxic, they must be removed before the head plate is removed. To remove the residual gas, a method is used in which an inert gas such as nitrogen is introduced into the pump column while the valve body of the foot valve assembly is closed (see, for example, Patent Document 1).

[0004] The valve disc is biased upward, i.e., in the valve closing direction, by a spring, and opens under the pump's own weight when the pump is operating (see, for example, Patent Document 2). Therefore, when the pump is lifted, the valve disc is closed by the biasing force of the spring. When inert gas is introduced into the pump column in this state, the residual gas returns to the storage tank while slightly opening the valve disc, and the inside of the pump column is purged with inert gas.

[0005] After purging, the valve disc is biased in the valve closing direction by a spring and hydraulic pressure corresponding to the amount (liquid level) of liquefied gas in the storage tank. As a result, the valve disc closes, and the protrusion on the valve disc presses against the opposing elastic material, sealing the foot valve assembly. In other words, the sealing performance of the foot valve assembly depends on the biasing force and hydraulic pressure. If the biasing force is increased to improve the sealing performance of the foot valve assembly, the valve disc will no longer open due to the pump's own weight, so there is a limit to how much the biasing force can be increased. Furthermore, if the amount (liquid level) of liquefied gas in the storage tank decreases, the hydraulic pressure will decrease, and the sealing performance of the foot valve assembly may deteriorate. As a result, a small amount of liquefied gas may leak into the foot valve assembly (into the pump column) during maintenance work. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-132619 [Patent Document 2] Japanese Utility Model Application Publication No. 05-78992 Summary of the Invention [Problem to be solved by the invention]

[0007] SUMMARY OF THE INVENTION An object of the present invention is to improve the sealing performance of a foot valve assembly in a submerged pump system. [Means for solving the problem]

[0008] In one embodiment of the present invention, a foot valve assembly includes: a cylindrical adapter attached to a lower open end of a cylindrical pump column that houses a pump that is immersed in pumped fluid and that houses the suction port of the pump; a disk-shaped valve element located below the lower end surface of the adapter and having a flow path forming surface that forms an inlet path between the adapter and the lower end surface and allows the pumped fluid to flow toward the pump, the disk-shaped valve element opening and closing the lower opening of the adapter; a biasing member that biases the valve element toward the adapter; and a one-way valve that is located in the inlet path and that opens in response to the pressure of the fluid released from the lower opening when the valve element is closed, and closes in response to the pumped fluid flowing toward the lower opening. a ring-shaped first seal member attached to the lower end surface of the adapter; Do not have The valve body is disposed opposite the first seal member and includes a ring-shaped protrusion protruding from the flow path forming surface toward the first seal member, and when the valve body is closed, the protrusion is pressed against the first seal member by the biasing force of the biasing member. .

[0009] One implementation of the present invention Aspects The submerged pump system in the above document comprises a pump that is immersed in the pumped liquid, a cylindrical pump column that houses the pump, and the foot valve assembly. [Effects of the Invention]

[0010] According to the present invention, the sealing performance of the foot valve assembly can be improved in a submerged pump system. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic cross-sectional view showing an embodiment of a submerged pump system according to the present invention. [Figure 2] 1 is a cross-sectional view showing an embodiment of a foot valve assembly according to the present invention. [Figure 3] FIG. 3 is a schematic enlarged cross-sectional view of a portion A of the foot valve assembly of FIG. 2. [Figure 4] FIG. 3 is a schematic enlarged cross-sectional view of part A of the foot valve assembly of FIG. 2 when the valve is closed. [Figure 5] 3 is a schematic enlarged cross-sectional view of part A of the foot valve assembly of FIG. 2 when an inert gas is being introduced. FIG. [Figure 6]3 is a schematic enlarged cross-sectional view of part A of the foot valve assembly of FIG. 2 after the introduction of the inert gas has been completed. FIG. [Figure 7] FIG. 4 is a schematic cross-sectional view showing a second embodiment of a submerged pump system according to the present invention. [Figure 8] FIG. 4 is a cross-sectional view showing a second embodiment of a foot valve assembly according to the present invention. [Figure 9] FIG. 9 is a schematic enlarged cross-sectional view of a portion B of the foot valve assembly of FIG. 8. [Figure 10] FIG. 9 is a schematic enlarged cross-sectional view of part B of the foot valve assembly of FIG. 8 when the valve is closed. [Figure 11] 9 is a schematic enlarged cross-sectional view of part B of the foot valve assembly of FIG. 8 when an inert gas is being introduced. [Figure 12] 9 is a schematic enlarged cross-sectional view of part B of the foot valve assembly of FIG. 8 after the introduction of the inert gas has been completed. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, the present invention will be described with reference to the drawings. Rusa An embodiment of a boosted pump system and a foot valve assembly will be described. In each drawing, the same components and elements are designated by the same reference numerals, and duplicated explanations will be omitted. In each drawing, the shapes and sizes of the components are intentionally exaggerated relative to their actual dimensions to clarify the configuration of each component.

[0013] In the following description and drawings, "downward" refers to the direction of gravity, and "upward" refers to the opposite direction of downward.

[0014] ●Submerged Pump System(1)● First, an embodiment of a submerged pump system according to the present invention will be described.

[0015] ●Configuration of Submerged Pump System (1) FIG. 1 is a schematic cross-sectional view showing an embodiment of a submerged pump system according to the present invention.

[0016] The submerged pump system 1 is attached to a storage tank T in which liquefied gas Lg is stored, and pumps the liquefied gas Lg from the storage tank T to the outside. The submerged pump system 1 includes a pump column 2, a sealing member 3, a support cable 4, a submerged pump (hereinafter referred to as "pump") 5, and a foot valve assembly 6. In this embodiment, the liquefied gas Lg is liquefaction Ammonia. Liquefied ammonia is an example of the handled liquid in the present invention.

[0017] In the present invention, the handled liquid is not limited to liquefied ammonia, and may be, for example, liquefied natural gas.

[0018] The pump column 2 houses the pump 5 and functions as a liquid transport path for the liquefied gas Lg discharged from the pump 5. The pump column 2 is cylindrical in shape. The pump column 2 is disposed so as to penetrate the ceiling T1 of the storage tank T and extends from the ceiling T1 into the liquefied gas Lg. A liquid transport path R1 for the liquefied gas Lg is connected to the outer peripheral surface of the upper part of the pump column 2. In the radial direction of the pump column 2, the lower end of the pump column 2 protrudes outward and forms a lower flange portion 2c.

[0019] The sealing member 3 liquid-tightly seals the upper open end 2a of the pump column 2, and supports the pump 5 by suspending it via a support cable 4 when the pump 5 is raised and lowered within the pump column 2. The sealing member 3 includes a head plate 3a that closes the upper open end 2a of the pump column 2, and a lift shaft 3b that is disposed to penetrate the head plate 3a. The lift shaft 3b is raised and lowered when the pump 5 is raised and lowered, and supports the pump 5 via the support cable 4.

[0020] The support cable 4 suspends and supports the pump 5 when the pump 5 is raised and lowered within the pump column 2. The support cable 4 is made of, for example, a metal wire. The support cable 4 is connected to the lift shaft 3b and the pump 5.

[0021] The pump 5 discharges the liquefied gas Lg that has flowed in from the foot valve assembly 6 into the pump column 2. The pump 5 is, for example, a known submerged pump that is configured with a multi-stage centrifugal pump and a motor that drives the multi-stage centrifugal pump. Power for the pump 5 is supplied via a power cable (not shown) that is connected to the sealing member 3. The pump 5 is housed in the lower part of the pump column 2 and is immersed in the liquefied gas Lg. The pump 5 moves between a lowered position and a lowered position in response to the elevation of the lift shaft 3b. rise The pump column 2 is raised and lowered between the above positions.

[0022] The "lowered position" is a position where the pump 5 is not lifted by the lift shaft 3b and is supported by an inclined surface 14 (described later) of the foot valve assembly 6. The "raised position" is a position where the pump 5 is suspended (lifted) from the lift shaft 3b via the support cable 4 when the lift shaft 3b is lifted to a predetermined height.

[0023] The foot valve assembly 6 opens and closes the lower open end 2b of the pump column 2. The specific configuration of the foot valve assembly 6 will be described later.

[0024] ●Configuration of foot valve assembly (1) Next, a specific configuration of the foot valve assembly 6 (the foot valve assembly according to the present invention) will be described.

[0025] FIG. 2 is a cross-sectional view showing an embodiment of the foot valve assembly 6. FIG. 3 is a schematic enlarged cross-sectional view of part A of the foot valve assembly 6 in FIG. Figures 2 and 3 show the foot valve assembly 6 when the pump 5 is in the lowered position. For ease of explanation, Figure 2 also shows the lower part of the pump column 2 and the pump 5. In the following explanation, the bolt holes corresponding to the first mounting bolts B1, which will be described later, are well known and will not be described further. Figure 1 will be referenced as needed in the following explanation.

[0026] The foot valve assembly 6 includes an adapter 10, a valve body 20, a seal member 30, a retainer plate 40, a seal valve 50, a plurality of biasing units 60, a plurality of first mounting bolts B1, a plurality of second mounting bolts B2, and a mounting nut N.

[0027] The adapter 10 is a member that attaches the valve element 20 to the pump column 2 and functions as a housing for the foot valve assembly 6. The adapter 10 includes a cylindrical portion 11, a first flange portion 12, a second flange portion 13, an inclined surface 14, a plurality of insertion holes 15, a first recess 16, and a second recess 17.

[0028] The cylindrical portion 11 accommodates an intake port (suction manifold) 5a disposed at the lower end of the pump 5. The cylindrical portion 11 is substantially cylindrical in shape. In the following description of the adapter 10, the term "radial direction" refers to the radial direction of the cylindrical portion 11, and the term "circumferential direction" refers to the circumferential direction of the cylindrical portion 11.

[0029] The upper end of the cylindrical portion 11 protrudes outward in the radial direction to form a ring-shaped first flange portion 12. The lower end of the cylindrical portion 11 protrudes outward in the radial direction to form a ring-shaped second flange portion 13. In other words, the cylindrical portion 11 is molded integrally with the first flange portion 12 and the second flange portion 13.

[0030] In the vertical direction, the upper half of the inner circumferential surface of the cylindrical portion 11 continuously increases in diameter from the center toward the upper end, forming an inclined surface 14 .

[0031] The insertion holes 15 are through-holes that pass through the second flange portion 13 in the up-down direction. The insertion holes 15 are arranged at equal intervals around the outer edge of the second flange portion 13 in the circumferential direction.

[0032] The area of ​​the lower end surface 10a of the adapter 10 (the lower surface of the cylindrical portion 11 and the second flange portion 13; the same applies below) on the inner edge side is recessed upward in a ring-like plate shape to form a first recess 16. The first recess 16 has a plurality of female threaded holes 16a. The female threaded holes 16a are arranged at equal intervals in the circumferential direction in the first recess 16.

[0033] The area of ​​the lower end surface 10a of the adapter 10 near the outer edge is recessed upward in a ring-like plate shape to form a second recess 17. The second recess 17 is located at the inner edge of the second recess 17 and has a side surface 17a that extends along the up-down direction. An insertion hole 15 is arranged at the outer edge of the second recess 17. In the radial direction, the second recess 17 is arranged outward of the first recess 16 and concentric with the first recess 16. The side surface 17a is an example of a movement restricting portion according to the present invention.

[0034] The adapter 10 is attached to the lower open end 2b of the pump column 2 by fastening the first flange portion 12 to the lower flange portion 2c of the pump column 2 with first mounting bolts B1 and mounting nuts N.

[0035] The valve element 20 opens and closes the lower opening 11a of the cylindrical portion 11 (i.e., the lower opening of the adapter 10). The shape of the valve element 20 is disk-shaped. The diameter of the valve element 20 is approximately the same as the outer diameter of the second flange portion 13 of the adapter 10. The valve element 20 includes a flow path forming surface 21, a convex portion 22, a plurality of vortex dissipation plates 23, a protrusion 24, and a plurality of insertion holes 25. In the following description of the valve element 20, "radial direction" means the radial direction of the valve element 20, and "circumferential direction" means the circumferential direction of the valve element 20.

[0036] The flow path forming surface 21 is the surface of the upper surface 20a of the valve body 20 that is located below the lower end surface 10a of the adapter 10. As will be described later, the flow path forming surface 21 forms an inflow path FL between the lower end surface 10a and the flow path forming surface 21, which allows the liquefied gas Lg to flow toward the pump 5 when the valve body 20 is open (when the valve is open).

[0037] The center of the valve body 20 protrudes upward in a generally truncated cone shape (mountain shape), forming a protrusion 22. The protrusion 22 reinforces the valve body 20 and guides the liquefied gas Lg that has flowed in from the inflow channel FL to the pump 5.

[0038] The vortex suppression plates 23 suppress the generation of vortices in the liquefied gas Lg that flows in from the inflow channel FL. The shape of the vortex suppression plates 23 is a substantially trapezoidal plate. The vortex suppression plates 23 are arranged in a region from the inside of the flow path forming surface 21 on the upper surface 20a of the valve body 20 to the outer edge of the protrusion 22, with both surfaces aligned in the radial direction. The vortex suppression plates 23 are also arranged at equal intervals in the circumferential direction. The upper surfaces 23a of the vortex suppression plates 23 are located above the top surfaces 22a of the protrusions 22.

[0039] When the valve body 20 is closed (valve closed), the protrusion 24 seals the inlet channel FL together with the seal member 30. A portion of the flow channel forming surface 21 located below the first recess 16 protrudes upward in a ring shape to form the protrusion 24. In the radial direction, the cross-sectional shape of the protrusion 24 is a triangle that is convex upward.

[0040] The fitting holes 25 are through-holes that pass through the valve body 20 in the up-down direction. The fitting holes 25 are arranged at equal intervals in the circumferential direction at positions that face the insertion holes 15.

[0041] The valve element 20 is attached to the adapter 10 so as to be able to open and close the lower opening 11a of the cylindrical portion 11 by the biasing unit 60. At this time, the protrusion 24 is disposed opposite the seal member 30 and protrudes from the flow path forming surface 21 toward the seal member 30. The details of the attachment of the valve element 20 will be described later.

[0042] When the valve is closed, the seal member 30 seals the inlet channel FL together with the protrusion 24. The seal member 30 is, for example, a ring-shaped gasket. The seal member 30 is made of, for example, a fluororesin such as PTFE (polytetrafluoroethylene). The seal member 30 is disposed in the first recess 16. The seal member 30 has a plurality of insertion holes 30a. In the circumferential direction of the seal member 30, the insertion holes 30a are disposed at equal intervals in positions facing the female threaded holes 16a. The seal member 30 is an example of a first seal member in the present invention.

[0043] The pressing plate 40 fixes the sealing member 30 to the first recess 16. The pressing plate 40 is shaped, for example, like a ring plate. The pressing plate 40 is disposed in the first recess 16. The pressing plate 40 has a plurality of insertion holes 40a. In the circumferential direction of the pressing plate 40, the insertion holes 40a are disposed at equal intervals in positions facing the insertion holes 30a of the sealing member 30.

[0044] The sealing member 30 and the pressing plate 40 are attached to the first recess 16 by threading the second mounting bolt B2, which is inserted through the two insertion holes 30a, 40a, into the female threaded hole 16a. At this time, the sealing member 30 is sandwiched between the first recess 16 and the pressing plate 40.

[0045] When closed, the seal valve 50 functions as a one-way valve that opens in response to the pressure of the fluid discharged from the lower opening 11a of the cylindrical portion 11 and closes in response to the liquefied gas Lg flowing toward the lower opening 11a. The seal valve 50 is formed, for example, of a ring-shaped packing. In this embodiment, the cross-sectional shape of the seal valve 50 is a "V" shape having two arms 51 and 52, but the seal valve 50 is not limited to a V-shaped packing having such a cross-sectional shape. The seal valve 50 is made of rubber such as EPDM (Ethylene Propylene Diene Monomer). That is, the seal valve 50 is formed of a single elastic material. The inner diameter of the seal valve 50 is slightly smaller than the diameter of the side surface 17a of the second recess 17. The lengths of the arms 51 and 52 are longer than the depth (vertical length) of the second recess 17.

[0046] The sealing valve 50 is attached to the adapter 10 by being fitted into the second recess 17. The tips of the arms 51 and 52 are directed toward the outer edge of the adapter 10. That is, the cross-sectional shape of the sealing valve 50 attached to the adapter 10 is a "<" or ">" shape with the two tips directed toward the outer edge. Of the arms 51 and 52, one arm 51 abuts against the second recess 17, and the other arm 52 is directed diagonally downward. The tip of the arm 52 protrudes slightly downward from the second recess 17. The arm 52 is an example of a deformable portion in the present invention.

[0047] The biasing unit 60 attaches the valve body 20 to the adapter 10 and biases the valve body 20 toward the adapter 10. The biasing unit 60 includes a shaft member 61, a spring 62, and a retainer 63.

[0048] The shaft member 61 guides the expansion and contraction of the spring 62. The shaft member 61 has a cylindrical shape extending in the up-down direction. The shaft member 61 is inserted from below into the insertion hole 25 of the valve body 20 and the insertion hole 15 of the adapter 10. The lower part of the shaft member 61 is inserted into the insertion hole 25. A part of the shaft member 61 protrudes above the second flange portion 13.

[0049] The spring 62 expands and contracts along the shaft member 61, and biases the valve body 20 toward the adapter 10. The spring 62 is, for example, a coil spring. The spring 62 is disposed above the second flange portion 13. The portion of the shaft member 61 that protrudes above the second flange portion 13 is inserted into the spring 62.

[0050] The retainer 63 fixes the position of one end (upper end) of the spring 62 relative to the shaft member 61. The retainer 63 is, for example, shaped like a ring plate. The retainer 63 is attached to the upper end of the shaft member 61 in a state in which the upper end of the spring 62 is pressed downward. As a result, the spring 62 is disposed between the retainer 63 and the second flange portion 13. The spring 62 biases the retainer 63 upward, thereby biasing the valve body 20 upward, i.e., toward the adapter 10, via the shaft member 61.

[0051] ●Operation of the foot valve assembly (1) Next, we will explain the operation of the foot valve assembly 6. Of the operations of the foot valve assembly 6, the opening and closing operation of the foot valve assembly 6 (i.e., the opening and closing operation of the valve element 20) is a well-known operation, so a detailed explanation of this will be omitted. In the following explanation, Figures 1 to 3 will be referenced as appropriate.

[0052] In the following description, the "upstream side" and "downstream side" of the inflow channel FL refer to the direction of flow of the liquefied gas Lg in the inflow channel FL. That is, for example, when the pump 5 is operating, the "upstream side" of the inflow channel FL refers to the outer edge side of the valve body 20 (the outer edge side of the second flange portion 13), and the "downstream side" of the inflow channel FL refers to the center side of the valve body 20 (the inner edge side of the second flange portion 13).

[0053] Operation when the valve is opened When the pump 5 is in the lowered position, the foot valve assembly 6 is opened by the weight of the pump 5 resisting the biasing force (hereinafter simply referred to as the "biasing force") of the spring 62. At this time, the lower end face of the pump 5 abuts against the upper face 23a of the vortex dissipation plate 23, and a part of the pump 5 abuts against the inclined face 14.

[0054] When the valve is open, an inlet channel FL is formed between the lower end surface 10a of the adapter 10 and the flow path forming surface 21 of the valve body 20. As a result, the liquefied gas Lg flows from the storage tank T through the inlet channel FL into the space between the vortex dissipation plates 23. Next, the liquefied gas Lg is rectified by the vortex dissipation plates 23 and guided to the pump 5 by the convex portions 22.

[0055] Here, the first recess 16 and the second recess 17 constitute a part of the lower end surface 10a. In other words, the lower end surface 10a includes the first recess 16 and the second recess 17. Therefore, the first recess 16 and the second recess 17 define a part of the inflow channel FL. Therefore, in this embodiment, the seal member 30, the presser plate 40, and the seal valve 50 are disposed in the inflow channel FL.

[0056] The arm portion 52 of the seal valve 50 is on the outer edge side of the adapter 10 and faces diagonally downward. Therefore, the arm portion 52 is pushed downstream by the liquefied gas Lg flowing through the inlet channel FL. As a result, the seal valve 50 is also pushed downstream. At this time, the seal valve 50 is supported by the side surface 17a of the second recess 17 and does not move downstream. In this way, the side surface 17a functions as a movement restriction portion in the present invention.

[0057] Operation when the valve is closed FIG. 4 is a schematic enlarged cross-sectional view of a portion A in FIG. 2 when the valve is closed.

[0058] The foot valve assembly 6 is closed by the biasing force when the lower end surface of the pump 5 is separated from the upper surface 23a of the vortex dissipation plate 23 (for example, when the pump 5 is in the raised position).

[0059] When the valve is closed, the protrusion 24 is pressed against the seal member 30 by an urging force. As a result, the protrusion 24 and the seal member 30 block the inflow channel FL. Meanwhile, the flow channel forming surface 21 of the valve body 20 is pressed against the arm portion 52 by an urging force in accordance with the protrusion length of the arm portion 52 of the seal valve 50 from the second recess 17. Therefore, the arm portion 51 abuts against the second recess 17, and the arm portion 52 abuts against the flow channel forming surface 21. As a result, the seal valve 50 blocks the inflow channel FL. Furthermore, the angle formed between the arm portion 52 and the flow channel forming surface 21 (hereinafter referred to as the "arm angle") is an acute angle on the downstream side of the arm portion 52 and an obtuse angle on the upstream side of the arm portion 52.

[0060] In the inflow channel FL, a space S having a width corresponding to the depth of the second recess 17 is formed between the second recess 17 and the flow channel forming surface 21. This space S is in communication with the inside of the storage tank T. Therefore, the liquefied gas Lg in the storage tank T is filled in this space S.

[0061] Operation from the time of inert gas introduction to the time of introduction completion The pump 5 is periodically (for example, every few years) removed from the pump column 2 for maintenance. Removing the pump 5 requires closing the foot valve assembly 6 and removing (purging) the residual gas (liquefied gas Lg and vaporized liquefied gas Lg) from the pump column 2. Removal (purging) of the residual gas is performed by introducing an inert gas into the pump column 2 after closing the foot valve assembly 6.

[0062] FIG. 5 is a schematic enlarged cross-sectional view of the portion A of the foot valve assembly 6 in FIG. 2 when the inert gas is being introduced. In the figure, the flow of residual gas is indicated by solid arrows, and the direction of deformation of the arm portion 52 is indicated by hollow arrows.

[0063] When the inert gas is introduced into the pump column 2, the residual gas in the pump column 2 is pressed downward by the pressure of the inert gas, and the valve element 20 opens slightly against the biasing force of the spring 62. As a result, a small gap is created between the upper end of the protrusion 24 and the seal member 30, and the residual gas is released through this gap to the downstream side of the protrusion 24. At this time, the pressure of the arm portion 52 by the flow path forming surface 21 is relaxed. However, the arm portion 52 is still in contact with the flow path forming surface 21, as shown by the dashed line in FIG. 5 . Therefore, the residual gas released to the downstream side of the protrusion 24 is blocked by the arm portion 52.

[0064] The residual gas released downstream of protrusion 24 applies downstream pressure to arm 52. As described above, the tip of arm 52 is directed toward the outer edge of adapter 10 (i.e., the upstream side), and the arm angle on the upstream side of arm 52 is an acute angle. Therefore, arm 52 is subjected to upward downstream pressure by the residual gas.

[0065] Here, the space above the arm portion 52 is filled with liquefied gas Lg, but the arm portion 52 resists this pressure almost solely through its own elastic force. Therefore, when the pressure applied to the arm portion 52 exceeds the elastic force of the arm portion 52, the arm portion 52 is bent (deformed) upward toward the downstream side by the pressure. As a result, the residual gas is released (purged) downstream of the arm portion 52, i.e., into the storage tank T. In this way, the arm portion 52 functions as a deforming portion in the present invention.

[0066] FIG. 6 is a schematic enlarged cross-sectional view of part A in FIG. 2 after the introduction of the inert gas has been completed.

[0067] When the introduction of the inert gas into the pump column 2 is completed (when the residual gas is purged), the pump column 2 and the foot valve assembly 6 are filled with inert gas. At this time, a hydraulic pressure corresponding to the liquid amount (liquid level) of the liquefied gas Lg stored in the storage tank T is applied to the lower surface 20b of the valve body 20. In other words, the valve body 20 is biased toward the adapter 10 by the biasing force and hydraulic pressure. At this time, the protrusion 24 is pressed against the seal member 30 by the biasing force and hydraulic pressure.

[0068] The liquefied gas Lg reaches the seal valve 50 through the space S between the second recess 17 and the flow path forming surface 21. At this time, the arm portion 52 abuts against the flow path forming surface 21. As described above, the arm angle on the upstream side of the arm portion 52 is obtuse. Therefore, the arm portion 52 is subjected to hydraulic pressure from the liquefied gas Lg directed diagonally downward downstream. At this time, because the arm portion 52 abuts against the flow path forming surface 21, the arm portion 52 cannot deform downward. Furthermore, when the arm portion 52 is pushed downstream, frictional force is generated at the contact point between the arm portion 52 and the flow path forming surface 21, preventing the arm portion 52 from deforming downstream. In this way, the arm portion 52 cannot deform downward or downstream, and the inlet channel FL is sealed by the seal valve 50. With this structure, the sealing performance of the seal valve 50 is largely independent of the biasing force, but rather relies on hydraulic pressure, elastic force, and frictional force.

[0069] When the amount of liquefied gas Lg in the storage tank T decreases, the liquid pressure decreases. As a result, the force pressing the protrusion 24 against the seal member 30 decreases in accordance with the amount of decrease in liquid pressure. Even in this case, the protrusion 24 is pressed against the seal member 30 mainly by the biasing force. Meanwhile, although the liquid pressure applied to the arm portion 52 decreases, the arm portion 52 is still pressed downward downstream and abuts against the flow path forming surface 21. Therefore, downward and downstream deformation of the arm portion 52 is inhibited in the same way as before the decrease in liquid level. As a result, the inflow channel FL is sealed by the seal valve 50 regardless of the liquid level.

[0070] Thus, when the inert gas is introduced, the arm portion 52 opens (deforms) in response to the pressure of the fluid (residual gas and inert gas) being discharged from the lower opening 11a of the cylindrical portion 11 toward the inlet channel FL, thereby discharging the fluid upstream. On the other hand, after the introduction of the inert gas is completed, the arm portion 52 closes (does not deform) due to the hydraulic pressure of the fluid (liquefied gas Lg) flowing from the upstream side toward the downstream side (toward the lower opening 11a). In other words, the seal valve 50 (specifically, the arm portion 52) functions as a one-way valve in the present invention.

[0071] The downstream side of the seal valve 50 is sealed by the protrusion 24 and the seal member 30. In other words, after the inert gas introduction is complete, the inlet channel FL is doubly sealed by the seal valve 50, the protrusion 24, and the seal member 30. In this embodiment, the handled liquid is liquefied ammonia, and the vaporized gas is ammonia gas, which is flammable and highly toxic to living organisms. Furthermore, ammonia gas is lighter than air, so it is easily inhaled by maintenance workers. The foot valve assembly 6 according to the present invention has a double sealing structure, making it suitable for handling liquids that are difficult to handle, such as liquefied ammonia.

[0072] Summary (1) According to the embodiment described above, the foot valve assembly 6 includes an adapter 10, a valve element 20, a spring 62, and a seal valve 50. The adapter 10 is attached to the lower open end 2b of the pump column 2. The valve element 20 is located below the lower end surface 10a of the adapter 10 and has a flow path forming surface 21 that forms an inlet channel FL between itself and the lower end surface 10a, thereby opening and closing the lower opening 11a of the cylindrical portion 11. The spring 62 biases the valve element 20 toward the adapter 10. The seal valve 50 is disposed in the inlet channel FL and, when closed, functions as a one-way valve that opens in response to the pressure of the fluid released from the lower opening 11a and closes in response to the liquefied gas Lg flowing toward the lower opening 11a. With this configuration, when the valve is closed, the inlet channel FL is sealed by the seal valve 50, which is a one-way valve. Therefore, in the foot valve assembly 6, purging of residual gas with inert gas is easier and sealing performance after purging is improved compared to conventional foot valve assemblies that are sealed only by protrusions and elastic material. Furthermore, the seal valve 50 opens and closes according to the pressure of the fluid applied to the seal valve 50. In other words, the seal valve 50 opens and closes independently of the biasing force. Therefore, the seal valve 50 can maintain its sealing performance regardless of the biasing force. Therefore, according to the present invention, the sealing performance of the foot valve assembly 6 in the submerged pump system 1 is improved compared to that of conventional foot valve assemblies.

[0073] Furthermore, according to the embodiment described above, the foot valve assembly 6 includes a ring-shaped seal member 30 attached to the lower end surface 10a (first recess 16) of the adapter 10. The valve element 20 is disposed opposite the seal member 30 and includes a protrusion 24 that protrudes from the flow path forming surface 21 toward the seal member 30. When the valve is closed, the protrusion 24 is pressed against the seal member 30 by an urging force. With this configuration, when the valve is closed, the inlet channel FL is doubly sealed by the protrusion 24, the seal member 30, and the seal valve 50. Therefore, the sealing performance of the foot valve assembly 6 is improved over that achieved by the protrusion 24 and the seal member 30 or the seal valve 50 alone.

[0074] Furthermore, according to the embodiment described above, the seal valve 50 is disposed radially outward of the protrusion 24 of the valve body 20. With this configuration, the seal valve 50, which can maintain sealing performance regardless of the biasing force, is disposed upstream (outside) of the protrusion 24 in the inflow passage FL. Therefore, in the inflow passage FL, the liquefied gas Lg from the storage tank T is blocked by the seal valve 50 and does not leak to the protrusion 24. Even if the liquefied gas Lg reaches the downstream side (inside) of the seal valve 50, the liquefied gas Lg is blocked by the protrusion 24 and the seal member 30. In this way, the seal valve 50, which does not depend on the biasing force, is disposed upstream of the protrusion 24 and the seal member 30, which depend on the biasing force and the liquid volume, thereby improving the sealing performance of the foot valve assembly 6.

[0075] Furthermore, according to the embodiment described above, the adapter 10 has a side surface 17a that restricts movement of the seal valve 50 in the radial direction of the valve body 20. The seal valve 50 is attached to the second recess 17. With this configuration, the seal valve 50 does not move in the radial direction of the valve body 20 due to the fluid flowing through the inlet channel FL. Therefore, the seal valve 50 can stably seal the inlet channel FL. As a result, the sealing performance of the foot valve assembly 6 is stable and improved.

[0076] Furthermore, according to the embodiment described above, the seal valve 50 is made of a ring-shaped elastic material and includes an arm portion 52 that deforms in response to the pressure of the fluid flowing upstream through the inlet channel FL. With this configuration, the one-way valve can be easily constructed using a single ring-shaped elastic material, such as a V-packing. The seal valve 50 opens and closes due to the pressure applied to the seal valve 50 and the elastic force of the arm portion 52. In other words, the sealing performance of the seal valve 50 depends on the pressure and elastic force, not the biasing force. Therefore, the seal valve 50 can maintain its sealing performance regardless of the biasing force. Therefore, the sealing performance of the foot valve assembly 6 is improved with a simple configuration.

[0077] ●Submerged Pump System (2)● Next, another embodiment (hereinafter referred to as the "second embodiment") of the submerged pump system and foot valve assembly according to the present invention will be described, focusing on the differences from the previously described embodiment (hereinafter referred to as the "first embodiment"). The second embodiment differs from the first embodiment in that the foot valve assembly is provided with a second seal member. In the following description, elements common to the first embodiment will be given the same reference numerals, and Figures 1 to 3 will be referenced as appropriate, with their description omitted.

[0078] ●Configuration of Submerged Pump System (2) FIG. 7 is a schematic cross-sectional view showing a second embodiment of a submerged pump system according to the present invention.

[0079] The submerged pump system 1A is attached to a storage tank T in which liquefied gas Lg is stored, and pumps the liquefied gas Lg from the storage tank T to the outside. The submerged pump system 1A includes a pump column 2, a sealing member 3, a support cable 4, a pump 5, and a foot valve assembly 6A.

[0080] ●Configuration of foot valve assembly (2) FIG. 8 is a cross-sectional view showing a second embodiment of a foot valve assembly 6A. FIG. 9 is a schematic enlarged cross-sectional view of part B of the foot valve assembly 6A of FIG. This figure shows the foot valve assembly 6A when the pump 5 is in the lowered position (valve open). For ease of explanation, Figure 8 also shows the lower parts of the pump column 2 and pump 5. In the following description, Figure 7 will be referenced as appropriate.

[0081] The foot valve assembly 6A includes an adapter 10A, a valve body 20A, a sealing member (hereinafter referred to as the "first sealing member" in the second embodiment) 30, a pressure plate 40, a sealing valve 50, a plurality of biasing units 60, a second sealing member 70, a plurality of first mounting bolts B1, a plurality of second mounting bolts B2, and a mounting nut N.

[0082] The adapter 10A is a component that attaches the valve element 20A to the pump column 2 and functions as a housing for the foot valve assembly 6A. The adapter 10A includes a cylindrical portion 11, a first flange portion 12, a second flange portion 13, an inclined surface 14, an insertion hole 15, a first recess 16, a first seal groove 18, and a second seal groove 19. In the following description of the adapter 10A, the term "radial direction" refers to the radial direction of the cylindrical portion 11, and the term "circumferential direction" refers to the circumferential direction of the cylindrical portion 11.

[0083] The configuration of the lower end surface 10a of the adapter 10A is the same as the configuration of the lower end surface 10a in the first embodiment, except that a first seal groove 18 and a second seal groove 19 are arranged instead of the second recess 17.

[0084] The first seal groove 18 is a ring-shaped groove in which the seal valve 50 is disposed. The cross-sectional shape of the first seal groove 18 is rectangular in the radial direction. The first seal groove 18 is located at the inner edge of the first seal groove 18 and has a side surface 18a that extends along the up-down direction. In the radial direction, the first seal groove 18 is disposed on the lower end surface 10a of the adapter 10A outward of the first recess 16 and concentric with the first recess 16. The depth (length in the up-down direction) of the first seal groove 18 is shorter than the length of the arm portions 51, 52. The side surface 18a is an example of a movement restricting portion in the present invention.

[0085] The second seal groove 19 is a ring-shaped groove in which the second seal member 70 is disposed. In the radial direction, the second seal groove 19 is disposed concentrically with the first recess 16 on the lower end surface 10a of the adapter 10A, outward of the first seal groove 18.

[0086] The adapter 10A is attached to the lower open end 2b of the pump column 2 with a first mounting bolt B1 and a mounting nut N, similar to the adapter 10 in the first embodiment.

[0087] The valve element 20A opens and closes the lower opening 11a of the cylindrical portion 11. The valve element 20A is disk-shaped. The diameter of the valve element 20A is approximately the same as the outer diameter of the second flange portion 13 of the adapter 10A. The valve element 20A includes a flow path forming surface 21, a convex portion 22, a plurality of vortex dissipation plates 23, a protrusion 24, a plurality of insertion holes 25, and a recess 26. In the following description of the valve element 20A, "radial direction" means the radial direction of the valve element 20A, and "circumferential direction" means the circumferential direction of the valve element 20A.

[0088] The configuration of the flow path forming surface 21 is the same as the configuration of the flow path forming surface 21 of the first embodiment, except that the recessed portion 26 is arranged therein.

[0089] The recess 26 is a ring-shaped groove against which the lower end of the second seal member 70 abuts when the valve is closed. The cross section of the recess 26 is rectangular in the radial direction. The recess 26 is disposed on the flow path forming surface 21 below the second seal groove 19 and concentric with the protrusion 24.

[0090] The valve body 20A is attached to the cylindrical portion 11 by the biasing unit 60 so as to be able to open and close the lower opening 11a, similar to the valve body 20 in the first embodiment.

[0091] When the valve is closed, the second seal member 70 abuts against the lower end surface 10a (second seal groove 19) of the adapter 10A and the flow path forming surface 21 (recess 26) to block the inlet channel FL. The second seal member 70 is, for example, a ring-shaped O-ring. That is, the cross-sectional shape of the second seal member 70 is circular. The material of the second seal member 70 is, for example, rubber such as EPDM. The second seal member 70 is fitted into the second seal groove 19. The lower end of the second seal member 70 protrudes downward from the second seal groove 19. The protruding length of the second seal member 70 in the vertical direction is longer than the length (depth) of the recess 26.

[0092] ●Operation of the foot valve assembly (2) Next, the operation of the foot valve assembly 6A will be explained, focusing on the differences from the operation of the foot valve assembly 6 in the first embodiment. In the following explanation, Figures 7 to 9 will be referenced as appropriate. In the following explanation, the terms "upstream side" and "downstream side" have the same meanings as those in the first embodiment.

[0093] Operation when the valve is opened When the valve is open, an inflow passage FL is formed between the lower end surface 10a of the adapter 10A and the passage forming surface 21 of the valve body 20A.

[0094] As in the first embodiment, the seal valve 50 is pushed downstream by the liquefied gas Lg in the inlet channel FL. At this time, the seal valve 50 does not move downstream because it is supported by the side surface 18a of the first seal groove 18. In this way, the side surface 18a functions as a movement restriction portion in the present invention.

[0095] The lower end of the second seal member 70 protrudes downward from the second seal groove 19. Therefore, the second seal member 70 is pushed downstream, similar to the seal valve 50. In the radial direction, the cross-sectional shape of the lower end of the second seal member 70 is semicircular, and the resistance that the liquefied gas Lg flowing through the inlet channel FL receives from the second seal member 70 is smaller than the resistance that the second seal member 70 receives from the seal valve 50. In addition, the second seal member 70 is fitted into the second seal groove 19. Therefore, the second seal member 70 does not move downstream.

[0096] Here, the first recess 16, the first seal groove 18, and the second seal groove 19 constitute a part of the lower end surface 10a. In other words, the lower end surface 10a includes the first recess 16, the first seal groove 18, and the second seal groove 19. Furthermore, the recess 26 constitutes a part of the flow path forming surface 21. In other words, the flow path forming surface 21 includes the recess 26. Therefore, the first recess 16, the first seal groove 18, the second seal groove 19, and the recess 26 define a part of the inflow path FL. Therefore, the first seal member 30, the presser plate 40, the seal valve 50, and the second seal member 70 are disposed within the inflow path FL.

[0097] Operation when the valve is closed FIG. 10 is a schematic enlarged cross-sectional view of part B in FIG. 8 when the valve is closed.

[0098] When the valve is closed, the protrusion 24, the first seal member 30, and the seal valve 50 seal the inflow passage FL, similar to the first embodiment.

[0099] The recess 26 of the valve body 20A is pressed against the lower end of the second seal member 70 by an urging force. At this time, the second seal member 70 is compressed (deformed) in the vertical direction by the second seal groove 19 and the recess 26, and abuts against the second seal groove 19 and the flow path forming surface 21 (recess 26). As a result, the second seal member 70 blocks the inflow path FL. Here, the second seal member 70 is compressed in the vertical direction within the range of the second seal groove 19 and the recess 26. Therefore, the lower end surface 10a abuts against the flow path forming surface 21 at positions adjacent to the upstream and downstream sides of the second seal groove 19 (recess 26).

[0100] Operation from the time of inert gas introduction to the time of introduction completion FIG. 11 is a schematic enlarged cross-sectional view of part B in FIG. 8 when the inert gas is introduced. In the figure, the flow of residual gas is indicated by solid arrows, and the direction of deformation of the arm portion 52 is indicated by hollow arrows.

[0101] When the valve body 20A opens slightly due to the pressure of the inert gas, the residual gas is released downstream of the seal valve 50, as in the first embodiment. Also, small gaps are formed between the lower end surface 10a and the flow path forming surface 21, and between the second seal member 70 and the flow path forming surface 21. The residual gas released downstream of the arm portion 52 is released (purged) through these gaps to the downstream side of the second seal member 70, i.e., into the storage tank T.

[0102] FIG. 12 is a schematic enlarged cross-sectional view of part B in FIG. 8 after the introduction of the inert gas has been completed.

[0103] When the introduction of the inert gas into the pump column 2 is completed (when the residual gas is purged), the valve element 20A is biased toward the adapter 10A by the biasing force and hydraulic pressure. At this time, the biasing force and hydraulic pressure press the protrusion 24 against the first seal member 30, press the recess 26 against the second seal member 70, and bring the lower end surface 10a into contact with the flow path forming surface 21. In addition, the arm portion 52 is in contact with the flow path forming surface 21. At this time, the inlet channel FL is sealed by the second seal member 70.

[0104] When the amount of liquefied gas Lg in the storage tank T decreases, the liquid pressure decreases. As a result, the force pressing the protrusion 24 against the seal member 30 and the force pressing the recess 26 against the second seal member 70 decrease in accordance with the amount of decrease in liquid pressure. Even in this case, the protrusion 24 is pressed against the seal member 30, the recess 26 is pressed against the second seal member 70, and the lower end surface 10a abuts against the flow path forming surface 21, mainly due to the biasing force.

[0105] Here, as the liquid pressure decreases, the liquefied gas Lg may enter between the lower end surface 10a and the flow path forming surface 21, and between the recess 26 and the second seal member 70. As a result, the liquefied gas Lg may reach the downstream side of the second seal member 70. However, the downstream side of the second seal member 70 is sealed by the seal valve 50, as in the first embodiment. Therefore, the liquefied gas Lg does not leak downstream of the seal valve 50.

[0106] In this way, the seal valve 50 functions as a one-way valve, just like in the first embodiment. After the inert gas has been introduced, the inlet passage FL is triple-sealed by the second seal member 70, the seal valve 50, the protrusion 24, and the first seal member 30. Because the foot valve assembly 6A according to the present invention has a triple-sealed structure, it is even more suitable for handling liquids that are difficult to handle, such as liquefied ammonia.

[0107] Summary (2) According to the embodiment described above, the foot valve assembly 6A has a common configuration with the foot valve assembly 6 in the first embodiment. Therefore, the foot valve assembly 6A has the same effects as the foot valve assembly 6 in the first embodiment.

[0108] Furthermore, according to the embodiment described above, the foot valve assembly 6A is provided with a second seal member 70 that abuts against the lower end surface 10a of the adapter 10A and the flow path forming surface 21 when the valve is closed. With this configuration, when the valve is closed, the inlet channel FL is triple-sealed by the protrusion 24, first seal member 30, seal valve 50, and second seal member 70. Therefore, the sealing performance of the foot valve assembly 6A is improved beyond that achieved by the protrusion 24, seal member 30, and / or seal valve 50 alone.

[0109] Furthermore, according to the embodiment described above, the second seal member 70 is disposed radially outward (upstream) of the seal valve 50 in the adapter 10A. With this configuration, the inflow passage FL is sealed upstream by the second seal member 70, whose sealing performance depends on the biasing force and hydraulic pressure. Even if the sealing performance of the second seal member 70 is reduced due to a drop in hydraulic pressure, causing liquefied gas Lg to reach the downstream side of the second seal member 70, the inflow passage FL is sealed by the seal valve 50, which does not rely on the biasing force. Thus, the inflow passage FL is sealed by the second seal member 70 when the biasing force and hydraulic pressure are sufficient, and is sealed by the seal valve 50, which does not rely on the biasing force, when the biasing force and hydraulic pressure are reduced. As a result, the sealing performance of the foot valve assembly 6A is improved.

[0110] Furthermore, according to the embodiment described above, the second seal member 70 is attached to the second seal groove 19 of the adapter 10A. The valve disc 20A has a recess 26 against which the second seal member 70 abuts when the valve is closed. With this configuration, by compressing the second seal member 70 within the recess 26, the lower end surface 10a of the adapter 10A can abut against the flow path forming surface 21 at positions adjacent to the upstream and downstream sides of the recess 26. As a result, the sealing performance of the foot valve assembly 6A is improved compared to a state in which a gap exists between the lower end surface 10a and the flow path forming surface 21.

[0111] Other embodiments In each of the above-described embodiments, the seal valve 50 may be attached to the valve body 20, 20A. In this case, for example, the outer edge portion of the flow path forming surface 21 of the valve body 20, 20A may be recessed in the shape of a ring plate, forming a recess corresponding to the second recess 17 in each of the embodiments.

[0112] Furthermore, in the second embodiment described above, the second seal member 70 may be attached to the valve body 20A. In this case, for example, the recess 26 of the valve body 20A may be configured so that the second seal member 70 is fitted into it. In this case, when the valve is closed, the second seal member 70 may abut against the lower end surface 10a (second seal groove 19) of the adapter 10A.

[0113] Furthermore, in each of the embodiments described above, the foot valve assembly 6, 6A does not have to include the protrusion 24 and the seal member 30 (first seal member 30). That is, for example, when the foot valve assembly 6, 6A is closed, it may be sealed only by the seal valve 50, or by the seal valve 50 and the second seal member 70.

[0114] Furthermore, in each of the above-described embodiments, the cross-sectional shape of the top of the protrusion 24 is not limited to the illustrated shape (pointed shape). That is, for example, the cross-sectional shape may be semicircular or flat.

[0115] Furthermore, in the first embodiment described above, the second recess 17 may be a ring-shaped groove. In this case, when the valve is closed, the lower end surface 10a of the adapter 10 may abut against the flow path forming surface 21 on the upstream and downstream sides of the second recess 17.

[0116] Furthermore, in each of the embodiments described above, the valve body 20, 20A may be provided with a recess at a position facing the seal valve 50, against which the deformed arm portion 52 abuts.

[0117] Furthermore, in each of the embodiments described above, the sealing valve 50 may be disposed downstream of the protrusion 24 in the inflow passage FL.

[0118] Furthermore, in the second embodiment described above, the seal valve 50 may be disposed in the inflow passage FL on the upstream side (outside) of the second seal member 70. In this case, the first seal groove 18 may be configured by recessing the outer edge portion of the lower end surface 10a of the adapter 10A into a ring-shaped plate.

[0119] Furthermore, in each of the above-described embodiments, the cross-sectional shape of the tip of the arm portion 52 is not limited to the illustrated shape (rectangular shape). That is, for example, the cross-sectional shape may be tapered so that the area in contact with the flow path forming surface 21 is increased.

[0120] Furthermore, in the second embodiment described above, the valve body 20A does not necessarily have to have the recess 26. In this case, the second seal member 70 abuts against the flow path forming surface 21, and gaps may be formed between the lower end surface 10a of the adapter 10A and the flow path forming surface 21 on the upstream and downstream sides of the second seal member 70.

[0121] Furthermore, in each of the embodiments described above, the second recess 17 (first seal groove 18) may be continuous with the first recess 16. That is, for example, the upstream (outer) portion of the first recess 16 may function as the second recess 17 (first seal groove 18). In this case, the seal valve 50 may be disposed in contact with the upstream (outer) side surface of the retainer plate 40, so that the retainer plate 40 may function as a movement restricting portion.

[0122] Furthermore, in each of the embodiments described above, the cross-sectional shape of the seal valve 50 is not limited to a V-shape. That is, for example, the cross-sectional shape of the seal valve 50 may be a Y-shape or a C-shape. Also, for example, the seal valve 50 may include a main body portion having a rectangular cross-sectional shape and a segment (arm portion) extending from the main body portion.

[0123] Furthermore, in each of the embodiments described above, the cross-sectional shape of the seal valve 50 may be I-shaped or L-shaped. In this case, the flow path forming surface 21 may have a recess at a position facing the seal valve 50, which prevents the arm portion (portion extending in the vertical direction) of the seal valve 50 from deforming downstream.

[0124] Furthermore, in each of the above-described embodiments, the material of the seal valve 50 is not limited to EPDM as long as it functions as a sealant for the pumped liquid. For example, the material of the seal valve 50 may be a fluororesin.

[0125] Furthermore, in the second embodiment described above, the material of the second seal member 70 is not limited to EPDM as long as it functions as a sealant for the pumped fluid. For example, the material of the second seal member 70 may be a fluororesin.

[0126] Furthermore, in each of the above-described embodiments, the material of the seal member 30 is not limited to PTFE, and may be any material that functions as a sealant for the pumped liquid.

[0127] Furthermore, in each of the embodiments described above, the arm portion 52 of the seal valve 50 does not have to protrude downward from the second recess 17 (first seal groove 18). In this case, the arm portion 52 does not abut against the flow path forming surface 21 when the valve is closed or while the inert gas is being introduced, and after the introduction of the inert gas is completed, the arm portion 52 may be raised downstream by the liquefied gas Lg and abut against the flow path forming surface 21.

[0128] ●Embodiments of the present invention● Next, the embodiments of the present invention that can be understood from the above-described embodiments will be described below, using the terms and symbols used in the embodiments.

[0129] A first embodiment of the present invention is a cylindrical pump column (e.g., pump column 2) that accommodates a pump (e.g., pump 5) immersed in a handled liquid (e.g., liquefied gas Lg) and is attached to a lower open end (e.g., lower open end 2b) of the pump column. The cylindrical adapter (e.g., adapter 10, 10A) accommodates an inlet (e.g., inlet 5a) of the pump, and a flow path forming surface (e.g., a flow path forming surface) that is located below the lower end surface (e.g., lower end surface 10a) of the adapter and forms an inlet path (e.g., inlet path FL) that allows the handled liquid to flow toward the pump. a one-way valve (e.g., seal valve 50) that is disposed in the inlet passage and that, when the valve is closed, opens in response to the pressure of the fluid released from the lower opening and closes in response to the pressure of the fluid, and that closes in response to the handled fluid flowing toward the lower opening. With this configuration, the sealing performance of the foot valve assembly in a submerged pump system is improved over that of conventional foot valve assemblies.

[0130] A second embodiment of the present invention is the first embodiment, wherein the adapter The aforementionedThis foot valve assembly comprises a ring-shaped first seal member (e.g., (first) seal member 30) attached to the lower end surface, the valve body is disposed opposite the first seal member and has a ring-shaped protrusion (e.g., protrusion 24) protruding from the flow path forming surface toward the first seal member, and when the valve body is closed, the protrusion is pressed against the first seal member by the biasing force of the biasing member. With this configuration, the inlet passage is doubly sealed, and therefore the sealing performance of the foot valve assembly is improved compared to sealing by the protrusion and sealing member or the sealing valve alone.

[0131] A third embodiment of the present invention is the foot valve assembly of the second embodiment, wherein the one-way valve is disposed outward from the protrusion in the radial direction of the valve body. According to this configuration, the sealing valve that does not depend on the biasing force is disposed upstream (outside) of the protrusion and sealing member that depend on the biasing force, thereby improving the sealing performance of the foot valve assembly.

[0132] A fourth embodiment of the present invention is any one of the first to third embodiments, wherein the one-way valve is attached to either the adapter or the valve body, and the adapter or the valve body to which the one-way valve is attached has a movement restriction portion ( for example, The foot valve assembly has sides 17a, 18a. With this configuration, the seal valve can stably seal the inlet passage, resulting in stable and improved sealing performance of the foot valve assembly.

[0133] A fifth embodiment of the present invention is a foot valve assembly in which, in any one of the first to fourth embodiments, the one-way valve is made of a ring-shaped elastic material and has a deforming portion (e.g., arm portion 52) that deforms in response to the pressure of the fluid. According to this configuration, the sealing performance of the foot valve assembly is improved with a simple configuration.

[0134] A sixth embodiment of the present invention is a foot valve assembly (e.g., foot valve assembly 6A) according to any one of the first to fifth embodiments, which has an annular second seal member (e.g., second seal member 70) that abuts against the lower end surface and the flow path forming surface when the valve body (e.g., valve body 20A) is closed. With this configuration, the sealing performance of the foot valve assembly is further improved compared to sealing achieved by the protrusion and the sealing member and / or the sealing valve alone.

[0135] A seventh embodiment of the present invention is the foot valve assembly of the sixth embodiment, wherein the second seal member is arranged outward of the one-way valve of the inlet passage in the radial direction of the adapter. This configuration improves the sealing performance of the foot valve assembly.

[0136] An eighth embodiment of the present invention is a foot valve assembly according to the sixth or seventh embodiment, wherein the second seal member is attached to either the adapter or the valve body, and at least one of the adapter or the valve body has a recess (e.g., recess 26) against which the second seal member abuts when the valve is closed. With this configuration, the sealing performance of the foot valve assembly is improved compared to when a gap is generated between the lower end surface and the flow path forming surface.

[0137] A ninth embodiment of the present invention is a submerged pump system comprising a pump immersed in a pumped liquid, a cylindrical pump column accommodating the pump, and a foot valve assembly according to any one of the first to eighth embodiments. With this configuration, the sealing performance of the foot valve assembly in a submerged pump system is improved over that of conventional foot valve assemblies. [Explanation of symbols]

[0138] 1 Submerged Pump System 2 Pump column 2b Lower open end 5. Pump 5a Intake port 6 Foot valve assembly 10 Adapters 10a Lower end surface 11a Bottom opening 17a Side (movement restriction part) 20 Valve body 21 Flow path forming surface 24 Protrusion 30 sealing member (first sealing member) 50 Seal valve (one-way valve) 52 Arm part (transformation part) 62 Spring 1A Submerged Pump System 6A Foot valve assembly 10A adapter 18 First seal groove 18a Side (movement restriction part) 19 Second seal groove 20A valve body 26 Recess 70 second seal member FL inflow path Lg liquefied gas

Claims

1. a cylindrical adapter attached to a lower open end of a cylindrical pump column that houses a pump that is immersed in the pumped liquid, and that houses a suction port of the pump; a disc-shaped valve body that is located below a lower end surface of the adapter and has a flow path forming surface that forms an inlet path between the adapter and the lower end surface and allows the pumped fluid to flow toward the pump, and that opens and closes a lower opening of the adapter; a biasing member that biases the valve body toward the adapter; a one-way valve that is disposed in the inlet passage and that opens to the fluid discharged from the lower opening in response to a pressure of the fluid when the valve body is closed, and closes to the pumped fluid flowing toward the lower opening; a ring-shaped first seal member attached to the lower end surface of the adapter; and the valve body is disposed opposite the first seal member and includes a ring-shaped protrusion that protrudes from the flow path forming surface toward the first seal member, When the valve body is closed, the protrusion is pressed against the first seal member by the biasing force of the biasing member. Foot valve assembly.

2. The one-way valve is disposed outward from the protrusion in the radial direction of the valve body.

2. The foot valve assembly of claim 1.

3. the one-way valve is attached to either the adapter or the valve body, The adapter or the valve body to which the one-way valve is attached includes a movement restricting portion that restricts movement of the one-way valve in the radial direction of the valve body.

3. A foot valve assembly according to claim 1 or 2.

4. The one-way valve is made of a ring-shaped elastic material and has a deformation portion that deforms in response to the pressure of the fluid.

4. A foot valve assembly according to any one of claims 1 to 3.

5. a second annular seal member that contacts the lower end surface and the flow path forming surface when the valve body is closed; 5. A foot valve assembly according to any one of claims 1 to 4.

6. In the radial direction of the adapter, the second seal member is disposed outward of the one-way valve of the inlet passage.

6. The foot valve assembly of claim 5.

7. the second seal member is attached to either the adapter or the valve body, At least one of the adapter and the valve body has a recess against which the second seal member abuts when the valve is closed.

7. A foot valve assembly according to claim 5 or 6.

8. a pump immersed in the handled liquid; a cylindrical pump column that houses the pump; The foot valve assembly according to any one of claims 1 to 7; consisting of Submerged pump system.

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