Submerged pump and method for extracting submerged pump

Abstract

A submerged pump 10 comprises a cylindrical barrel 15 fixed to a top wall 2, a protective pipe 36 connecting a plurality of cylindrical bodies 37 in the form of a linear pipe, a pump part 32 attached to the lower end of the protective pipe 36 and disposed in a barrel 15 together with the protective pipe 36 as an integrated unit, a plate-shaped upper cover 21 attached to the upper end of the barrel 15, and a receiving seat 40 that is detachably disposed on the upper cover 21 and that supports the pump part 32 via the protective pipe 36 by holding connecting parts 37a of the cylindrical bodies 37. The receiving seat 40 has insertion holes 41d which are smaller than the connecting parts 37a of the cylindrical bodies 37 and into which portions other than the connection parts 37a can be inserted.

Description

Submerged pump and method for extracting the same

[0001] The present invention relates to a submerged pump and a method for extracting a submerged pump.

[0002] Patent Document 1 discloses an ammonia tank discharge pump that discharges liquid ammonia from a tank. This pump includes a barrel inserted into the tank, a foot valve provided at the bottom of the barrel, and a discharge pump suspended within the barrel. During maintenance, the discharge pump is lifted to close the foot valve, and then the interior of the barrel is purified by supplying purge gas into the barrel while sucking gas from within the barrel. Thereafter, a head plate closing the top end of the barrel is removed, and the discharge pump is removed from the top end of the barrel to prevent ammonia gas from diffusing outside the barrel (to the atmosphere).

[0003] JP 2023-90418 A

[0004] It is difficult to completely purify the interior of the barrel by supplying purge gas. On the other hand, in the pump of Patent Document 1, the head plate is removed, and the dispensing pump is lifted from the bottom of the barrel and removed from the top, so vaporized gas can diffuse from the wide-open top end of the barrel to the outside (atmosphere). In other words, the pump of Patent Document 1 has room for improvement in terms of measures to prevent vaporized gas from diffusing from the barrel.

[0005] An object of the present invention is to prevent vaporized gas from diffusing into the atmosphere during maintenance.

[0006] The submerged pump of the present invention includes a cylindrical barrel fixed to the top wall and extending vertically within the tank with an open upper end, the barrel having a branched discharge portion located above the top wall of the tank, a protective tube formed by connecting multiple cylindrical bodies in a straight pipe shape and inserted into the barrel along the axis of the barrel, the protective tube having connecting portions protruding in a direction intersecting the axis of the barrel, a pump unit attached to the lower end of the protective tube and disposed within the barrel integrally with the protective tube, the pump unit discharging liquefied gas from the discharge portion through between the barrel and the protective tube, a plate-shaped upper cover attached to the upper end of the barrel and having an opening through which the connecting portions can be inserted, and a receiving seat having an insertion hole smaller than the connecting portions through which portions of the cylindrical bodies other than the connecting portions can be inserted, the receiving seat being detachably mounted on the upper cover to cover the opening, the receiving seat supporting the pump unit via the protective tube by holding the connecting portions. In a first aspect, the submerged pump is provided with a submerged pump, the receiving seat having an inner periphery provided with a seal protruding toward the protective tube. In a second aspect, there is provided a submerged pump, wherein the receiving seat is formed by dividing an annular body into two or more divided bodies in the circumferential direction.

[0007] Another aspect of the present invention provides a method for extracting a submerged pump, which is disposed within a cylindrical barrel fixed to the top wall of a tank and extending vertically within the tank, and which discharges liquefied gas from a discharge section of the barrel located above the top wall through a pump section attached to the lower end of a protective tube formed by connecting a plurality of cylindrical bodies in a straight pipe shape, the method including a lifting step of lifting the protective tube and the pump section together as a unit; a support step of placing a receiving seat on an upper cover attached to the upper end of the barrel so as to cover an opening of the upper cover, and holding on the receiving seat a connecting section at an upper end of the cylindrical body that protrudes in a direction intersecting the axis of the barrel and is exposed from the upper cover, thereby supporting the pump section via the protective tube; and a separation step of separating the cylindrical body above the receiving seat. After repeatedly performing these steps, an extraction step is performed in which, when the upper end of the cylindrical body at the lower end directly connected to the pump section becomes exposed from the upper cover, the pump section is extracted together with the upper cover from the top end of the barrel.

[0008] The pump unit is attached to the lower end of a protective tube, which is made up of multiple cylindrical bodies connected in a straight pipe shape, and is disposed within the barrel as a single unit with the protective tube. A support seat, detachably mounted on the upper cover, supports the pump unit via the protective tube by holding the connecting portion. Therefore, the pump unit can be lifted to the top of the barrel by repeatedly performing a lifting step in which the protective tube and the pump unit are lifted together, a support step in which the connecting portion of the cylindrical bodies is held by the support seat and the pump unit is supported via the protective tube, and a separation step in which the cylindrical bodies above the support seat are separated. The support seat covering the opening of the upper cover has an insertion hole that is smaller than the connecting portion of the cylindrical bodies and allows insertion of the portion other than the connecting portion. Therefore, in the case of a liquefied gas such as ammonia, leakage and diffusion of vaporized gas into the atmosphere can be minimized. The pump unit can then be removed from the barrel by performing an extraction step in which the pump unit is removed from the barrel together with the upper cover, improving maintainability.

[0009] In the present invention, the vaporized gas can be prevented from diffusing into the atmosphere during maintenance.

[0010] FIG. 2 is a cross-sectional view of a submerged pump according to an embodiment of the present invention attached to a tank. FIG. 3 is an enlarged cross-sectional view of part II of FIG. 1. FIG. 4 is an exploded perspective view of an upper cover at the upper end of the barrel and a receiving seat according to a first embodiment. FIG. 5 is a cross-sectional view of the receiving seat according to the first embodiment. FIG. 6 is a cross-sectional view showing a blocking process during maintenance. FIG. 7 is a cross-sectional view showing a connecting step of a lifting process during maintenance. FIG. 8 is a cross-sectional view showing a lifting step of a lifting process during maintenance. FIG. 9 is a cross-sectional view showing a supporting step of a lifting process during maintenance. FIG. 10 is a cross-sectional view showing a separating step of a lifting process during maintenance. FIG. 11 is a cross-sectional view showing a connecting step of a withdrawal process during maintenance. FIG. 12 is a cross-sectional view showing a withdrawal step of a withdrawal process during maintenance. FIG. 13 is a cross-sectional view of a receiving seat according to a second embodiment. FIG. 14 is a cross-sectional view of a receiving seat according to a third embodiment. FIG. 15 is a cross-sectional view of a receiving seat according to a fourth embodiment.

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0012] (First embodiment) Referring to Figure 1, a submerged pump 10 according to a first embodiment of the present invention is installed on a ceiling wall 2 of a tank 1 and discharges a liquefied gas (liquid) such as ammonia from the inside of the tank 1 to a specified external facility.

[0013] The submerged pump 10 includes a barrel 15, a pump section 32, and a protective tube 36. The pump section 32 is attached to the lower end of the protective tube 36. The pump section 32 and the protective tube 36 are inserted together into the barrel 15 from above. The submerged pump 10 also includes a receiving seat 40 that is used when the pump section 32 is inserted into and removed from the barrel 15.

[0014] The configurations of the barrel 15, the pump portion 32, the protective tube 36, and the receiving seat 40 will be specifically described below.

[0015] The barrel 15 is cylindrical with open top and bottom ends, and extends vertically within the tank 1, penetrating the top wall 2. The barrel 15 includes a base plate 15a for fixing to the top wall 2, and a portion of the upper side of the barrel 15 protrudes above the top wall 2 and is exposed to the atmosphere. The total length of the barrel 15 is determined according to the overall height of the tank 1, and is, for example, 50 m. Although the barrel 15 in FIG. 1 is illustrated as a single continuous straight pipe, in reality it is composed of multiple straight pipes connected in a liquid-tight manner. However, depending on the overall height of the tank 1, the barrel 15 may be composed of a single straight pipe.

[0016] A cylindrical liquid discharge port 15b, a gas inlet port 15c, and a gas outlet port 15d are branched and connected to a portion of the barrel 15 located above the top wall 2. The liquid discharge port 15b is connected to a delivery pipe 4 connected to downstream equipment. A gate valve 5 is installed in the delivery pipe 4. The gas inlet port 15c is connected to a gas supply source 7 for supplying an inert gas (e.g., N2 gas) into the barrel 15. The gas outlet port 15d is connected to equipment (not shown) that processes the inert gas and vaporized gas inside the barrel 15.

[0017] A foot valve 16 is attached to the lower end of the barrel 15. A seal member 24 is attached to the upper end of the barrel 15 via an upper cover 21.

[0018] The foot valve 16 includes a valve seat 17 and a valve element 18. The valve seat 17 is cylindrical and is attached liquid-tight to the lower end of the barrel 15 with bolts. The valve element 18 is disk-shaped and has the same diameter as the flange portion at the lower end of the valve seat 17, and is attached so as to be movable up and down relative to the valve seat 17. The valve element 18 may have a diameter different from the outer diameter of the flange portion of the valve seat 17, or may have a shape other than a disk, as long as it can close the valve seat 17 and close the valve.

[0019] The valve element 18 is provided with a plurality of shaft portions 18a and protrusions 18b spaced apart in the circumferential direction. The shaft portions 18a penetrate the flange portion of the valve seat 17 and protrude upward. A stopper 19 is attached to the upper end of the shaft portion 18a. A coil spring 20 is disposed between the stopper 19 and the flange portion, surrounding the shaft portion 18a, and biases the valve element 18 upward. The protrusions 18b protrude upward, and a portion of the protrusions 18b is located within the valve seat 17. When the pump portion 32 is placed on the protrusions 18b, the valve element 18 separates from the valve seat 17 against the biasing force of the coil spring 20, opening the valve (see FIG. 5). When the pump portion 32 separates from the protrusions 18b, the biasing force of the coil spring 20 presses the valve element 18 against the valve seat 17, closing the valve (see FIG. 7).

[0020] 2 and 3, the upper cover 21 is made of an annular metal plate and is attached by bolts to the flange 15e at the upper end of the barrel 15 in a liquid-tight and airtight manner. The center of the opening 21a of the upper cover 21 is located on the axis A. The diameter of the opening 21a is smaller than the outer shape of the pump section 32 and larger than the outer shape of the protective tube 36, and is large enough to allow the connecting section 37a of the protective tube 36, which will be described in detail later, to be inserted therethrough.

[0021] The outer periphery of the upper cover 21 is provided with a plurality of bolt holes 21b for bolting to the barrel 15. The inner periphery of the upper cover 21 is provided with a plurality of bolt holes 21c for bolting to the seal member 24. A pair of bolt holes 21d is provided between the bolt holes 21b and 21c, into which eyebolts 44 (see FIG. 10) attached to a lifting wire 43 are threadedly engaged. The bolt holes 21c and 21d are each a non-through, bottomed cylinder with an open upper end and a closed lower end.

[0022] A guide protrusion 22 is provided between the opening 21a and the bolt hole 21c of the upper cover 21. The guide protrusion 22 is configured to guide a pair of divided bodies 41 that make up the receiving seat 40. The guide protrusion 22 is configured by a stud bolt, and is detachably screwed into a bottomed cylindrical bolt hole 21e provided in the upper cover 21.

[0023] 1 and 2, the guide protrusions 22 are normally removed from the upper cover 21. As shown in FIGS. 3 and 6 to 11, the guide protrusions 22 are attached to the upper cover 21 when the pump unit 32 is pulled out or inserted into the barrel 15. When attached to the upper cover 21, the guide protrusions 22 protrude upward from the upper cover 21 along the axis A. Two guide protrusions 22 are used for each divided body 41, for a total of four guide protrusions 22. The number of guide protrusions 22 can be changed as needed as long as it is possible to guide the pair of divided bodies 41.

[0024] 2, sealing member 24 is configured to prevent vaporized gas in barrel 15 from leaking and diffusing to the outside through protective tube 36 under normal conditions. Sealing member 24 includes a bobbin-shaped base body 25 that is attached to upper cover 21 in a liquid-tight and airtight manner.

[0025] The lower flange portion 25a of the base body 25 has bolt through holes that correspond to the bolt holes 21c (see FIG. 3) of the upper cover 21. The sealing member 24 is connected to the upper cover 21 by threading bolts that pass through the lower flange portion 25a into the bolt holes 21c of the upper cover 21.

[0026] The upper flange of the base 25 is provided with bolt through holes for bolting the terminal block 28. A gland packing (not shown) is attached to the inner periphery between the lower flange 25a and the upper flange to seal the protective tube 36.

[0027] 1, a terminal block 28 is attached by bolts to the upper side of the seal member 24. A power supply connection portion for supplying power to the pump unit 32 and a control panel for controlling the pump unit 32 are connected to the terminal block 28.

[0028] The pump unit 32 is of an immersion type and is disposed at the lower end of the barrel 15. The pump unit 32 discharges liquefied gas that has entered the barrel 15 from the liquid discharge unit 15b through the gap between the barrel 15 and the protective tube 36. When disposed in the barrel 15, the pump unit 32 presses the valve element 18 downward to open the foot valve 16, and is then placed on the valve element 15. The pump unit 32 includes a motor and an impeller (not shown) within the casing. The motor is connected to the terminal block 28 by a cable 33 routed within the protective tube 36. The cable 33 is configured by connecting multiple electric wires via a connector 34. The cable 33 may also be configured as a single electric wire without being connected by the connector 34.

[0029] 1 , the protective tube 36 is cylindrical overall and is configured to protect the cable 33. The protective tube 36 is made of metal and configured by connecting multiple cylindrical bodies 37 in a straight pipe shape, and is inserted into the barrel 15 along the axis A. The outer diameter of each cylindrical body 37 is the same and is smaller than the inner diameter of the barrel 15 as well as the inner diameter of the opening 21a of the upper cover 21. The overall length of each cylindrical body 37 is a length (e.g., 5 m) that can be lifted by a crane (lifting mechanism) not shown. The connectors 34 for the cable 33 described above are attached to the upper and lower ends of the cylindrical bodies 37.

[0030] Of the multiple cylindrical bodies 37, connecting portions 37a protruding radially outward are provided at the upper and lower ends of each body except for the lower cylindrical body 37A and the upper cylindrical body 37B. The connecting portion 37a is provided only at the upper end of the cylindrical body 37A, and the pump section 32 is connected to the lower end of the cylindrical body 37A. The connecting portion 37a is provided only at the lower end of the cylindrical body 37B. The multiple cylindrical bodies 37 are connected in a straight pipe shape by overlapping the connecting portions 37a of adjacent cylindrical bodies 37 vertically and fastening them with bolts.

[0031] The connecting portion 37a is configured as a flange that protrudes in a circular ring shape relative to the cylindrical body 37. The outer diameter of the connecting portion 37a is smaller than the diameter of the opening 21a of the upper cover 21. This allows the connecting portion 37a to pass through the opening 21a of the upper cover 21 and be removable from the upper end of the barrel 15. As long as the connecting portion 37a is configured to protrude radially outward relative to the cylindrical body 37, it may be an interrupted circular ring shape or may have a shape other than a ring.

[0032] The top of the upper cylinder 37B protrudes upward, penetrating the upper cover 21 and the seal member 24. Referring to Figure 6, during maintenance, a connecting member 38 for connecting a wire 43 is attached to the upper end of the cylinder 37B. The connecting member 38 is annular and has an outer diameter larger than the diameter of the opening 21a of the upper cover 21. The connecting member 38 has a bolt hole into which an eyebolt 44 for the wire 43 is threaded.

[0033] 6 to 8, the receiving seat 40 is used when inserting and removing the pump unit 32 from the barrel 15, and is detachably disposed on the upper cover 21. The receiving seat 40 is made of metal, and supports the pump unit 32 in a suspended position via the protective tube 36 by holding the connecting portion 37a at the upper end of the cylindrical body 37.

[0034] 2 to 4, the receiving seat 40 of the first embodiment is configured by a pair of divided bodies 41 obtained by dividing a bobbin-shaped annular body as a whole into two in the circumferential direction. Each divided body 41 includes a base 41a, a lower support portion 41b provided at the lower end of the base 41a, and an upper support portion 41c provided at the upper end of the base 41a, and forms an annular shape when in use with the divided bodies 41 facing each other so that their linear divided edges are in contact. The receiving seat 40 may be configured by three or more divided bodies 41.

[0035] The base 41a is semi-cylindrical with an inner diameter larger than the outer diameter of the main body of the cylindrical body 37 and smaller than the outer diameter of the connecting portion 37a, and is formed into a cylindrical shape by arranging the pair of divided bodies 41 facing each other and close to each other. The internal space of the base 41a forms an insertion hole 41d through which the portion of the cylindrical body 37 other than the connecting portion 37a can be inserted.

[0036] A seal portion 41e is provided by joining on the inner periphery of the base portion 41a, protruding radially inward toward the protective tube 36. The seal portion 41e is semicircular and is formed by arranging the pair of divided bodies 41 facing each other and close to each other. The inner diameter of the seal portion 41e is larger than the outer diameter of the main body of the cylindrical body 37 excluding the connecting portion 37a, but is set as small as possible within the range that allows the cylindrical body 37 to be inserted.

[0037] The lower support portion 41b is joined to the lower end of the base portion 41a. The lower support portion 41b has a semicircular ring shape, which is formed by arranging the pair of segments 41 facing each other and in close proximity. The outer diameter of the lower support portion 41b is larger than the diameter of the opening 21a of the upper cover 21. The outer diameter of the lower support portion 41b is also smaller than the dimension between the pair of bolt holes 21d in the upper cover 21, i.e., the imaginary diameter at the position where the bolt holes 21d are formed in the upper cover 21. This allows the bolt holes 21d to be exposed when the receiving seat 40 is placed on the upper cover 21.

[0038] The lower support portion 41b has a pair of guide grooves 41f extending from the outer periphery toward the dividing edge. The pair of guide grooves 41f extend parallel to the dividing edge in a direction perpendicular to the dividing edge. By inserting the guide protrusions 22 of the upper cover 21 into these guide grooves 41f, the pair of divided bodies 41 can be guided in a direction in which they approach each other (radially inward) or move away from each other (radially outward). When the pair of divided bodies 41 are spaced apart, the connecting portion 37a of the protective tube 36 can be inserted through the insertion hole 41d. When the pair of divided bodies 41 are close to each other, the connecting portion 37a of the protective tube 36 cannot be inserted through the insertion hole 41d.

[0039] The upper support portion 41c is joined to the upper end of the base portion 41a. The upper support portion 41c has a semicircular ring shape, which is formed by arranging the pair of divided bodies 41 facing each other and close to each other. The outer diameter of the upper support portion 41c is larger than the outer diameter of the connecting portion 37a of the cylindrical body 37 and smaller than the outer diameter of the lower support portion 41b. The outer diameter of the upper support portion 41c is large enough to expose the guide groove 41f. A plurality of reinforcing ribs 41g are provided between the upper support portion 41c and the lower support portion 41b at intervals in the circumferential direction. The ribs 41g are joined to the base portion 41a, the lower support portion 41b, and the upper support portion 41c, respectively.

[0040] Next, a method for removing the pump portion 32 of the submerged pump 10 from the barrel 15 during maintenance will be described.

[0041] The method for extracting the submerged pump 10 of this embodiment includes a shutoff step shown in FIG. 5, a lifting step shown in FIGS. 6 to 9, and an extraction step shown in FIGS.

[0042] In the shutoff process, the gate valve 5 shown in Fig. 1 is switched from an open state to a closed state. Also, as shown in Fig. 5, the terminal block 28 is removed from the seal member 24, and the cable 33 is disconnected.

[0043] Next, in the lifting step, the gas supply source 7 is activated to start supplying inert gas to the gas inlet 15c, thereby purging the inside of the barrel 15 (purging step). In addition, in the lifting step, in parallel with the purging step, the connecting step shown in Fig. 6, the lifting step shown in Fig. 7, the supporting step shown in Fig. 8, and the separating step shown in Fig. 9 are repeatedly performed until the connecting portion 37a of the lower end cylindrical body 37A is exposed.

[0044] Specifically, when lifting the uppermost (first from the top) cylindrical body 37B, in the connecting step shown in Figure 6, first, the bolts on the lower flange portion 25a of the seal member 24 are removed to release the connection of the seal member 24 to the upper cover 21. Next, the seal member 24 is removed from the cylindrical body 37B. After that, a pair of divided bodies 41 are placed on the upper cover 21 on which the guide protrusions 22 (see Figure 3) are arranged. Furthermore, a connecting member 38 is attached to the upper end of the cylindrical body 37B, and an eyebolt 44 attached to the tip of a wire 43 is screwed into the connecting member 38.

[0045] 7, the wire 43 is raised by a crane to raise the pump unit 32 via the protective tube 36. This separates the pump unit 32 from the valve body 18, and closes the foot valve 16. When the connecting portion 37a at the upper end of the second cylindrical body 37 connected to the first cylindrical body 37B becomes exposed above the upper cover 21, more specifically, above the receiving seat 40, the raising of the wire 43 by the crane is stopped.

[0046] 8, the pair of divided bodies 41 are moved toward each other along the guide grooves 41f (see FIG. 3) so that the opening 21a of the upper cover 21 is covered by the receiving seat 40. After that, the wire 43 is pulled down by the crane to place the connecting portion 37a of the second cylindrical body 37 on the receiving seat 40. As a result, the pump unit 32 is supported in a suspended state by the receiving seat 40 via the protective tube 36.

[0047] 9, the bolt connecting the connecting portion 37a of the cylindrical bodies 37B and 37 is removed. After that, the wire 43 is again pulled up by the crane, and the connection of the cable 33 by the connector 34 is released. This separates the cylindrical body 37B above the receiving seat 40.

[0048] 6, the connecting, lifting, supporting, and separating of the second and subsequent cylinders 37 from the top are repeated until the connecting portion 37a of the lowermost cylinder 37A is exposed. When lifting the second and subsequent cylinders 37, the eyebolt 44 is threaded onto the connecting portion 37a of the cylinder 37 located on the receiving seat 40 instead of the connecting member 38, but the other points are the same. During this time, the purging step continues.

[0049] In the lifting process, a receiving seat 40 having an insertion hole 41d through which only the main body of the cylindrical body 37 can be inserted is placed above the opening 21a of the upper cover 21 through which the protective tube 36 can be inserted. Moreover, the receiving seat 40 is formed with a seal portion 41e that protrudes toward the protective tube 36 so as to make the gap as small as possible within the range that allows the main body of the cylindrical body 37 to be inserted. This effectively prevents the vaporized gas inside the barrel 15 from leaking and diffusing to the outside.

[0050] As shown in Figure 10, the connecting portion 37a of the lower end cylindrical body 37A connected to the pump section 32 is supported by the receiving seat 40, and the cylindrical body 37 on the receiving seat 40 is separated, and then the extraction process is carried out. In the connecting step shown in Figure 10 of the extraction process, the eyebolt 44 is threaded into the bolt hole 21d of the upper cover 21. In addition, the bolt connecting the flange 15e of the barrel 15 to the upper cover 21 is removed. In addition, the gas supply source 7 is stopped, and the supply of inert gas to the gas inlet portion 15c is stopped.

[0051] 11, the wire 43 is pulled up by a crane. As a result, the pump unit 32 is pulled out from the upper end of the barrel 15, and the upper cover 21 and the lower cylindrical body 37A are removed together with the pump unit 32.

[0052] On the other hand, when placing the pump unit 32 inside the barrel 15 after maintenance, the procedure for removing the pump unit 32 from the barrel 15 is reversed. That is, the steps of connecting the other cylindrical bodies 37, 37B to the cylindrical bodies 37A, 37 supported by the receiving seats 40 with bolts and then lowering them using a crane are repeated. This allows the pump unit 32 to be placed inside the barrel 15 installed in the tank 1, as shown in FIG. 1 .

[0053] The submerged pump 10 configured in this manner has the following features.

[0054] The pump unit 32 is attached to the lower end of a protective tube 36, which is made up of multiple cylindrical bodies 37 connected in a straight pipe shape, and is disposed within the barrel 15 integrally with the protective tube 36. A receptacle 40, which is detachably disposed on the upper cover 21, supports the pump unit 32 via the protective tube 36 by holding the connecting portions 37a. Therefore, the pump unit 32 can be lifted to the top of the barrel 15 by repeatedly performing a lifting step in which the protective tube 36 and the pump unit 32 are lifted together, a support step in which the connecting portions 37a of the cylindrical bodies 37 are held by the receptacle 40 and the pump unit 32 are supported via the protective tube 36, and a separation step in which the cylindrical bodies 37 above the receptacle 40 are separated. Furthermore, because the separation step is performed with the pump unit 32 suspended by the receptacle 40 via the protective tube 36, the operation of separating the cylindrical bodies 37 above the receptacle 40 can be easily and stably performed.

[0055] The receiving seat 40 covering the opening 21a of the upper cover 21 has an insertion hole 41d that is smaller than the connecting portion 37a of the cylindrical body 37 and allows the portion other than the connecting portion 37a to be inserted therethrough, so that in the case of a liquefied gas such as ammonia, leakage of vaporized gas into the atmosphere and diffusion can be minimized. Then, by performing an extraction step in which the pump unit 32 is extracted together with the upper cover 21 from the top end of the barrel 15, the pump unit 32 can be extracted from the barrel 15, thereby improving maintainability.

[0056] A seal portion 41e that protrudes toward the protective tube 36 is provided on the inner periphery of the receiving seat 40. Therefore, the seal portion 41e can effectively prevent the vaporized gas from leaking between the inner periphery of the receiving seat 40 and the protective tube 36.

[0057] The receiving seat 40 is composed of divided bodies 41 obtained by dividing an annular body into two or more bodies. Therefore, the receiving seat 40 can be easily and reliably positioned so as to surround the outer periphery of the cylindrical body 37 of the protective tube 36 that is lifted above the upper cover 21.

[0058] The divided body 41 is formed with a guide groove 41f extending from the outer periphery toward the divided edge, and the upper cover 21 is provided with a guide protrusion 22 that is inserted into the guide groove 41f. Therefore, when the connecting portion 37a of the cylindrical body 37, which cannot pass through the insertion hole 41d, is lifted above the receiving seat 40, the divided body 41 can be easily passed by moving in a direction away from the receiving seat 40. Furthermore, after the connecting portion 37a is lifted, the divided body 41 can be easily returned to the support position by moving in a direction toward the receiving seat 40, and the pump section 32 can be reliably supported via the protective tube 36.

[0059] The connecting portion 37a is configured by a flange that protrudes radially outward from the cylindrical body 37. Therefore, there is no need to worry about directionality when arranging the receiving seat 40, and the receiving seat 40 can easily and stably hold the connecting portion 37a.

[0060] Other embodiments and various modifications of the present invention will be described below, but in these descriptions, points that are not particularly mentioned are the same as those in the first embodiment. In the drawings referred to below, the same elements as those in the first embodiment are denoted by the same reference numerals.

[0061] The seal portion 41e of the receiving seat 40 may be configured as shown in FIGS. 12 to 14. In the receiving seat 40 of a second embodiment shown in FIG. 12, multiple (three in this embodiment) seal portions 41e are provided at intervals along the axis A of the barrel 15 (the axis of the protective tube 36). In the receiving seat 40 of a third embodiment shown in FIG. 13, multiple (three in this embodiment) semicircular seal portions 41e are provided at intervals along the axis A of the barrel 15. In the receiving seat 40 of a fourth embodiment shown in FIG. 14, the seal portion 41e is formed in a spiral shape when a pair of divided bodies 41 are arranged facing each other in close proximity. With the receiving seat 40 configured as described above, it is possible to more effectively prevent the vaporized gas in the barrel 15 from leaking and diffusing to the outside when the pump portion 32 is pulled out of the barrel 15.

[0062] The present invention is not limited to the configuration of the above embodiment, and various modifications are possible.

[0063] For example, the seal portion 41e may be a separate body from the base portion 41a that constitutes the divided body 41, and may be made of a resin that has good sliding properties.

[0064] Receiving seat 45 may be formed of a single member instead of dividing an annular body in the circumferential direction. Specifically, receiving seat 45 may be formed in a C-shaped groove in an annular body including cylindrical base 46 a and annular support portions 46 b, 46 c, through which the portion of cylindrical body 41 other than connecting portion 41 a can be inserted, so as to form a C-shape when viewed from above.

[0065] Water (moisture) instead of the inert gas may be sprayed as a treatment agent into the inlet portion 15c of the barrel 15. If the seal portion 41e of the receiving seat 40 can prevent the vaporized gas in the barrel 15 from diffusing to the outside, the barrel 15 may be configured without the inlet portion 15c and the outlet portion 15d for supplying the inert gas.

[0066] The liquid discharged by the submerged pump 10 is not limited to liquefied gas such as ammonia, and can be changed as required.

[0067] DESCRIPTION OF SYMBOLS 1 Tank 2 Ceiling wall 4 Delivery pipe 5 Gate valve 7 Gas supply source 10 Submerged pump 15 Barrel 15a Base plate 15b Liquid discharge portion 15c Gas inlet portion 15d Gas outlet portion 15e Flange 16 Foot valve 17 Valve seat 18 Valve body 18a Shaft portion 18b Protrusion portion 19 Stopper 20 Coil spring 21 Upper cover 21a Opening portion 21b Bolt hole 21c Bolt hole 21d Bolt hole 21e Bolt hole 22 Guide protrusion 24 Seal member 25 Base body 25a Lower flange portion 28 Terminal block 32 Pump portion 33 Cable 34 Connector 36 Protective tube 37 Cylinder 37A Lower end cylinder 37B Upper end cylinder 37a Connecting portion 38 Connecting member 40 Receiving seat 41 Divided body 41a Base portion 41b Lower support portion 41c Upper support portion 41d Insertion hole 41e Sealing portion 41f Guide groove 41g Rib 43 Wire 44 Eyebolt

Claims

1. A submerged pump comprising: a cylindrical barrel fixed to the top wall of the tank, extending vertically within the tank, and having an open upper end, and having a branched discharge section located above the top wall; a protective tube formed by connecting multiple cylindrical bodies in a straight pipe shape, each having a connecting section protruding in a direction intersecting the axis of the barrel, and inserted into the barrel along the axis; a pump section attached to the lower end of the protective tube and disposed within the barrel integrally with the protective tube, for discharging liquefied gas from the discharge section through between the barrel and the protective tube; a plate-shaped upper cover attached to the upper end of the barrel, having an opening through which the connecting section can be inserted; and a receiving seat having an insertion hole smaller than the connecting section through which portions of the cylindrical bodies other than the connecting section can be inserted, detachably disposed on the upper cover so as to cover the opening, and supporting the pump section via the protective tube by holding the connecting section, wherein a seal section protruding toward the protective tube is provided on the inner periphery of the receiving seat.

2. A submerged pump according to claim 1, wherein the receiving seat is formed by dividing an annular body into two or more segments in the circumferential direction.

3. A submerged pump comprising: a cylindrical barrel having a branched discharge section located above the top wall of the tank, fixed to the top wall, extending vertically within the tank, and open at its upper end; a protective tube formed by connecting multiple cylindrical bodies in a straight pipe shape, each having a connecting section protruding in a direction intersecting the axis of the barrel, and inserted into the barrel along the axis; a pump section attached to the lower end of the protective tube and disposed within the barrel integrally with the protective tube, for discharging liquefied gas from the discharge section through between the barrel and the protective tube; a plate-shaped upper cover attached to the upper end of the barrel, having an opening through which the connecting section can be inserted; and a receiving seat having an insertion hole smaller than the connecting section through which portions of the cylindrical bodies other than the connecting section can be inserted, detachably disposed on the upper cover so as to cover the opening, and supporting the pump section via the protective tube by holding the connecting sections, wherein the receiving seat is formed by dividing an annular body into two or more segments in the circumferential direction.

4. A submerged pump as claimed in claim 2 or 3, wherein the divided bodies are formed with guide grooves extending from the outer periphery towards the divided edges, and the upper cover is provided with detachable guide protrusions which are inserted into the guide grooves and guide the two or more divided bodies in contact and separation directions, i.e., directions in which they approach and move away from each other.

5. A submerged pump according to any one of claims 1 to 3, wherein the connecting portion is constituted by a flange that protrudes radially outward from the cylindrical body.

6. A method for extracting a submerged pump, which is disposed within a cylindrical barrel fixed to the top wall of a tank and extending vertically within the tank, and which discharges liquefied gas from a discharge section of the barrel located above the top wall through a pump section attached to the lower end of a protective tube formed by connecting multiple cylindrical bodies in a straight pipe, the method comprising: a lifting step for lifting the protective tube and the pump section together; a support step for placing a receiving seat on an upper cover attached to the upper end of the barrel so as to cover an opening of the upper cover, and holding on the receiving seat the connecting section of the upper end of the cylindrical body that protrudes in a direction intersecting the axis of the barrel and is exposed from the upper cover, thereby supporting the pump section via the protective tube; and a separation step for separating the cylindrical body above the receiving seat; and, when the upper end of the cylindrical body at the lower end directly connected to the pump section becomes exposed from the upper cover, an extraction step for extracting the pump section together with the upper cover from the top end of the barrel.

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