JP2018123683A - Low temperature fluid pump and low temperature fluid transfer device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low temperature fluid pump which can inhibit heat input to a cold temperature fluid, and to provide a low temperature fluid transfer device using the low temperature fluid pump.SOLUTION: A low temperature fluid pump 100 includes: an impeller 8; a rotary shaft including a first shaft 9 and a second shaft 31; an impeller shaft 10; a housing; and a magnetic bearing 11. The rotary shaft is used to rotationally drive the impeller 8. The impeller shaft 10 connects the rotary shaft with the impeller 8. The housing includes: an inner periphery side housing portion 6; an outer periphery side housing portion 40; a flange part 6c; an impeller shaft cover 6d; an impeller cover 6e; a second housing 7; and a lid body 18 and holds the rotary shaft therein. The magnetic bearing 11 rotatably supports the rotary shaft on the housing. The impeller shaft 10 is a hollow cylindrical body.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a cryogenic fluid pump and a cryogenic fluid transfer device.

  2. Description of the Related Art Conventionally, a cryogenic fluid pump for feeding a low temperature liquefied gas or the like is known. In such a cryogenic fluid pump, in particular, a pump used for an application where the pump cannot be stopped due to a failure or maintenance, such as a pump used for cooling a superconducting device that requires continuous operation for a long period of time. As a bearing, a magnetic bearing requiring no maintenance is adopted. For example, Japanese Patent Laying-Open No. 2013-57250 (Patent Document 1) discloses a cryogenic fluid pump having a configuration in which a magnetic bearing requiring no maintenance is employed as a bearing. In the cryogenic fluid pump disclosed in Patent Document 1, heat intrusion from the motor to the impeller side through the shaft is performed by magnetically coupling the upper shaft and the lower shaft of the motor, which are heat sources, in a non-contact state by a magnetic coupling. Is suppressed.

JP 2013-57250 A

  However, the heat source in the above-described cryogenic fluid pump is not limited to the motor. For example, since it is necessary to supply electric power to a magnetic bearing that supports the lower shaft in order to generate a supporting force, the magnetic bearing becomes a heat source. In this case, heat enters from the electromagnet coil of the magnetic bearing, which is a heat generation source, to the impeller side through the lower shaft. Also, heat is radiated to the low-temperature liquefied gas through the inner casing of the cryogenic fluid pump. As a result, the low-temperature liquefied gas in the low-temperature liquefied gas container in which the pump is installed is vaporized, so that the loss of the low-temperature liquefied gas increases and the pump efficiency also decreases.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a cryogenic fluid pump capable of suppressing heat input to a cold fluid and the cryogenic fluid pump. It is to provide a cryogenic fluid transfer device used.

  A cryogenic fluid pump according to the present disclosure includes an impeller, a rotating shaft, an impeller shaft, a housing, and a magnetic bearing. The rotating shaft is for rotating the impeller. The impeller shaft connects the rotating shaft and the impeller. The housing holds the rotating shaft inside. A magnetic bearing supports a rotating shaft rotatably with respect to a housing | casing. The impeller shaft is a hollow cylindrical body.

  A cryogenic fluid transfer device according to the present disclosure includes a container that accommodates a cryogenic fluid, the cryogenic fluid pump, and a flow conduit. The cryogenic fluid pump is installed in the container such that the impeller is disposed inside the container. The circulation pipe is connected to the container and is used for circulating a low-temperature fluid to which kinetic energy is imparted by a low-temperature fluid pump.

  According to the above, since the impeller shaft for connecting the rotating shaft supported by the magnetic bearing and the impeller has a thin hollow structure, heat transfer from the electromagnetic coil of the magnetic bearing, which is a heat generation source, to the impeller can be reduced. it can. In addition, since the housing supporting the magnetic bearing has a double structure, it is possible to reduce the heat intrusion from the magnetic bearing to the low-temperature fluid such as the low-temperature liquefied gas existing outside the low-temperature fluid pump. Thus, an efficient cryogenic fluid pump and cryogenic fluid transfer device can be realized.

It is a schematic diagram of the cryogenic fluid transfer apparatus which concerns on embodiment of this invention. It is a cross-sectional schematic diagram of the cryogenic fluid pump used for the cryogenic fluid transfer apparatus shown in FIG. It is a cross-sectional schematic diagram of the modification of the pump for low temperature fluids shown in FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated.

(Embodiment)
<Configuration of cryogenic fluid transfer device>
As shown in FIG. 1, the cryogenic fluid transfer apparatus 1 mainly includes a cryogenic fluid pump 100, a container 2, an inflow portion 3, and an outflow portion 4.

  The cryogenic fluid pump 100 includes a portion disposed outside the container 2 and a portion disposed inside the container 2. The cryogenic fluid pump 100 is attached to the pressure wall 5 of the container 2. Details of the cryogenic fluid pump 100 will be described later.

The container 2 is for storing therein a low-temperature fluid such as a low-temperature liquefied gas. The cryogenic fluid is, for example, liquid nitrogen (LN ₂ ). The container 2 is configured as a pressure-resistant container, and includes a main body that stores a low-temperature fluid therein and a pressure wall 5. For example, the main body has an opening at the top. The pressure wall 5 is connected to the main body so as to close the opening of the main body. The pressure wall 5 faces the internal space that stores the cryogenic fluid in the container 2. As shown in FIG. 1, the pressure wall 5 is disposed, for example, above the internal space of the container 2. As shown in FIG. 2, a through hole 5 a is formed in the pressure wall 5. In the through hole 5 a of the pressure wall 5, a portion disposed inside the container 2 in the cryogenic fluid pump 100 is inserted. The hole axis of the through hole 5a is, for example, arranged coaxially with the central axis of the first shaft 9 constituting the shaft of the pump 100 described later.

  In the portion of the pressure wall 5 located around the through hole 5a, a concave portion that is recessed toward the inner peripheral surface side with respect to the outer peripheral surface 5b of the pressure wall 5 is disposed. The said recessed part is a part into which the fixing member 14 mentioned later is screwed. The material that constitutes the pressure wall 5 is a material that is approved for use as a constituent material of a high-pressure gas container by laws and regulations, and includes, for example, stainless steel (SUS) or aluminum (Al).

  The inflow portion 3 includes a pipe line connected to the internal space of the container 2. The cryogenic fluid flows into the container 2 through the pipe line of the inflow portion 3. The outflow part 4 includes a pipe line connected to the internal space of the container 2. The cryogenic fluid flows out of the container 2 through the pipe line of the outflow portion 4.

  The inflow portion 3 and the outflow portion 4 are configured as a part of a flow conduit through which a low-temperature fluid flows. The distribution pipe includes a reservoir tank (not shown) and a refrigerator (not shown). The inflow part 3 is connected to a reservoir tank, for example. The outflow part 4 is connected with the refrigerator, for example.

  Further, from a different point of view, the cryogenic fluid transfer device described above includes a container 2 that accommodates cryogenic fluid, the cryogenic fluid pump 100, and a flow conduit including the inflow portion 3 and the outflow portion 4. The cryogenic fluid pump 100 is installed in the container 2 such that the impeller 8 is disposed inside the container 2 as shown in FIG. The distribution pipe is connected to the container 2 and is used for circulating the low-temperature fluid LG to which kinetic energy is given by the low-temperature fluid pump 100.

<Configuration of pump for cryogenic fluid>
As shown in FIG. 2, the cryogenic fluid pump 100 (hereinafter also simply referred to as a pump) according to the first embodiment is disposed so as to block the through hole 5 a disposed in the pressure wall 5 of the container 2. The cryogenic fluid pump 100 includes an impeller 8, a rotary shaft including a first shaft 9 and a second shaft 31, an impeller shaft 10, a housing, a radial magnetic bearing 11 as a magnetic bearing, and a second shaft 31. A motor 30 that rotates is mainly provided.

  The first shaft 9 and the second shaft 31 constituting the rotating shaft are coupled by the magnetic coupling 20 so as to be able to transmit the rotational force in a non-contact manner. The two radial magnetic bearings 11 support the first shaft 9 so as to be rotatable with respect to the housing. The two radial magnetic bearings 11 are spaced from each other in the extending direction of the first shaft 9. The magnetic coupling 20 includes a first coupling member 22 fixed to the end of the first shaft 9 and a second coupling member 21 fixed to the end of the second shaft 31. The second joint member 21 has a cup shape. The first joint member 22 is disposed inside the second joint member 21. Magnets are arranged in the opposing portions of the first joint member 22 and the second joint member 21. Due to the magnetic force generated by the magnet, the first joint member 22 and the second joint member 21 can transmit the rotational force without contact.

  A thrust magnetic bearing 12 is disposed at a position adjacent to the first joint member 22 on the first shaft 9. In addition, the radial magnetic bearing 11 is disposed in a portion of the first shaft 9 that is located on the side opposite to the first joint member 22 when viewed from the thrust magnetic bearing 12.

  The housing includes a first housing, a second housing 7 and a lid 18. The first housing includes an inner peripheral housing portion 6, an outer peripheral housing portion 40, a flange portion 6c, an impeller shaft cover 6d, and an impeller cover 6e. An upper end portion of the inner peripheral housing portion 6 is disposed in the through hole 5 b of the pressure wall 5. The flange portion 6 c is connected to the upper end portion of the inner peripheral housing portion 6. The first housing is arranged such that the flange portion 6 c extends on the outer peripheral surface 5 b of the pressure wall 5. The second housing 7 has a cylindrical shape, and a flange portion is formed at an end portion on the impeller 8 side. The flange portion of the second housing 7 is disposed so as to overlap the flange portion 6c of the first housing. A through hole for passing the fixing member 14 is formed in the flange portion of the second housing 7 and the flange portion 6c of the first housing. This through hole is arranged so as to overlap with a recess formed in the outer peripheral surface 5 b of the pressure wall 5. The first housing and the second housing 7 are fixed to the pressure wall 5 by screwing and fixing the fixing member 14 into the through hole and the recess.

  An opening is formed above the second housing 7. A lid 18 is disposed so as to close the opening of the second housing 7. A magnetic coupling 20 is disposed in an inner region of the casing surrounded by the lid 18 and the second casing 7. A motor 30 is installed on the outer peripheral side of the lid 18. A second shaft 31 is connected to the motor 30. An opening for inserting a part of the motor 30 is formed in the lid 18. A part of the motor 30 is inserted and fixed in the opening. In the motor 30, the second shaft 31 is disposed so as to protrude toward the inner peripheral side of the second housing 7 from the portion inserted into the opening.

  The inner peripheral housing portion 6, the outer peripheral housing portion 40, the impeller shaft cover 6 d and the impeller cover 6 e of the first housing are disposed inside the container 2. The inner peripheral housing part 6 and the outer peripheral housing part 40 have a cylindrical shape. The impeller shaft cover 6d is positioned on the inner peripheral housing portion 6 on the side facing the impeller 8, and is connected to the inner peripheral housing portion 6 and disposed so as to surround the impeller shaft 10. The impeller cover 6e is connected to the impeller shaft cover 6d and is disposed so as to surround the impeller 8.

  The impeller cover 6e is provided with an inlet 6a and an outlet 6b as openings. The inflow port 6a is disposed at the lower end of the impeller cover 6e and opens downward. The outlet 6b opens in the tangential direction of the outer peripheral surface of the impeller 8 as viewed from the extending direction of the central axis of the impeller 8 (the extending direction of the central axis of the first shaft 9).

  A radial magnetic bearing 11 is connected to the inner peripheral housing portion 6. The outer peripheral housing part 40 covers the inner peripheral housing part 6 from the outside, and is arranged with a gap from the inner peripheral housing part 6. The rotating shaft is for driving the impeller 8 to rotate. The impeller shaft 10 connects the first shaft 9 constituting the rotating shaft and the impeller 8. The extending direction of the first shaft 9 is, for example, the gravitational direction (vertical direction). The housing holds the first shaft 9 and the second shaft 31 as rotation axes inside. The radial magnetic bearing 11 supports the first shaft 9 constituting the rotation shaft so as to be rotatable with respect to the inner peripheral housing portion 6 which is a housing. The impeller shaft 10 is a hollow cylindrical body.

  As shown in FIG. 2, the outer peripheral housing part 40 is hermetically connected to the first end 43 on the impeller 8 side in the inner peripheral housing part 6, while the first in the inner peripheral housing part 6. The second end portion located on the opposite side of the end portion 43 is disposed with a space 41 therebetween. The gap is connected to the outside of the outer casing part 40 via the space 41. The end portion 42 on the motor 30 side of the outer casing portion 40 is a flange portion extending along the inner peripheral surface of the pressure wall 5. The end 42 of the outer casing part 40 is disposed above the liquid level of the low temperature fluid LG in the container 2. Therefore, the low temperature fluid LG does not flow into the gap between the inner peripheral housing portion 6 and the outer peripheral housing portion 40.

  In the cryogenic fluid pump 100, the lid 18, the second casing 7, the inner casing 6 of the first casing, the flange 6 c, the impeller shaft cover 6 d and the impeller cover 6 e are made of high-pressure gas according to laws and regulations. The material is approved for use as a constituent material of the container, and includes, for example, stainless steel (SUS) or aluminum (Al).

  In the cryogenic fluid pump 100, the outer casing portion 40 and the impeller shaft 10 of the first casing are made of a material having a relatively low thermal conductivity, for example, a stainless alloy or a resin material.

  The impeller 8 imparts kinetic energy to the cryogenic fluid LG in the container 2. The impeller 8 is configured as a centrifugal impeller, for example. The impeller 8 is connected to one end of the impeller shaft 10. The rotating shaft, the motor 30, the radial magnetic bearing 11 and the thrust magnetic bearing 12 constitute a drive unit that rotationally drives the impeller 8.

<Operation effect of cryogenic fluid transfer device and cryogenic fluid pump>
A cryogenic fluid pump 100 shown in FIGS. 1 and 2 is a top plate of a container 2 (low temperature liquefied gas container) that stores a low temperature liquefied gas as an example of a low temperature fluid, similarly to the pump disclosed in Patent Document 1. It is attached to a certain pressure wall 5. In the cryogenic fluid pump 100, the motor 30 is disposed outside the container 2, and at least the impeller 8 and the radial magnetic bearing 11 are disposed inside the container 2 in a state immersed in the cryogenic fluid. As described above, the magnetic coupling 20 is disposed between the second shaft 31 as the upper shaft driven by the motor 30 and the first shaft 9 as the lower shaft. For this reason, the driving force of the motor 30 is transmitted from the second shaft 31 to the first shaft 9 in a non-contact manner. Since the magnetic coupling 20 transmits the rotational force in a non-contact manner in this way, the movement of heat from the motor 30 that is a heat generation source to the impeller 8 side via the first shaft 9 is suppressed.

  On the other hand, it is necessary to supply electric power to the radial magnetic bearing 11 that supports the first shaft 9 in order to generate a supporting force. As a result, the radial magnetic bearing 11 becomes a heat source. Therefore, in the low-temperature fluid pump 100, the impeller shaft 10 that connects the impeller 8 and the first shaft 9 has a thin hollow structure to increase the thermal resistance. As a result, heat penetration from the radial magnetic bearing 11 to the impeller 8 is reduced. If it says from a different viewpoint, since the impeller shaft 10 is a hollow cylindrical body, the cross-sectional area of the impeller shaft 10 can be reduced compared with the case where the said impeller shaft 10 is solid. For this reason, when the heat generated from the radial magnetic bearing 11 as a heat source is conducted to the impeller 8 side through the first shaft 9 and the impeller shaft 10, the thermal resistance at the impeller shaft 10 which is a heat input path is increased. it can. Therefore, the amount of heat transmitted to the impeller 8 side through the impeller shaft 10 can be reduced. As a result, it is possible to suppress the gasification of the low temperature fluid LG and the decrease in pump efficiency in the low temperature fluid pump 100 due to the heat conduction to the impeller 8 side.

  Further, by adopting a double structure consisting of the inner peripheral side casing part 6 and the outer peripheral side casing part 40 for the part of the casing that is the casing part immersed in the low temperature fluid LG, the radial magnetic bearing 11 is provided. It can prevent that the inner peripheral side housing | casing part 6 to support contacts the cryogenic fluid LG directly. If it says from a different viewpoint, since the space | gap is formed between the inner peripheral side housing | casing part 6 and the outer peripheral side housing | casing part 40, the outer peripheral side housing | casing passes from the radial magnetic bearing 11 via the inner peripheral side housing | casing part 6. FIG. The amount of heat transmitted to the body part 40 can be reduced. In addition, since the cryogenic fluid pump 100 is arranged so that the second end located above the inner casing portion 6 is above the liquid level of the cryogenic fluid LG, without sealing the gap. It can be set as the state which formed the space | gap in which the low temperature fluid LG does not exist between the inner peripheral side housing | casing part 6 and the outer peripheral side housing | casing part 40. FIG. As a result, the movement of heat from the inner peripheral housing portion 6 to the external low temperature fluid LG via the outer peripheral housing portion 40 can be reduced.

  Further, in the above-described cryogenic fluid pump 100, the outer casing portion 40 and the impeller shaft 10 of the first casing are made of either a stainless alloy or a resin material. On the other hand, even if the cryogenic fluid pump 100 is applied, the soundness of the outer casing portion 40 and the impeller shaft 10 of the first casing can be maintained.

  In the cryogenic fluid transfer device 1 to which the cryogenic fluid pump 100 shown in FIG. 2 is applied, the heat intrusion from the heat source such as the radial magnetic bearing 11 to the impeller 8 side or the cryogenic fluid LG is reduced as described above. Can do. As a result, it is possible to realize a highly efficient low-temperature fluid transfer apparatus 1 that has little loss such as vaporization of a low-temperature fluid and can suppress a decrease in efficiency of the pump.

<Configuration and effect of modification>
The cryogenic fluid transfer apparatus having the cryogenic fluid pump shown in FIG. 3 basically has the same configuration as the cryogenic fluid transfer apparatus shown in FIGS. 1 and 2, but the cryogenic fluid pump has a single configuration. The department is different. Specifically, in the cryogenic fluid pump shown in FIG. 3, the inner peripheral housing portion 6 and the outer peripheral housing portion 40 are the inner peripheral housing portion 6 and the outer peripheral housing portion 40. It connects so that the space | gap formed between may be airtightly sealed. The space may be in a reduced pressure state reduced from atmospheric pressure or in a vacuum. In this case, heat transfer due to gas convection in the gap between the inner peripheral housing portion 6 and the outer peripheral housing portion 40 can be reduced, and the heat insulating performance of the void can be improved.

  Specifically, in the cryogenic fluid pump 100 shown in FIG. 3, the end 42 of the outer casing 40 is sandwiched and fixed between the lower surface of the flange portion 6 c and the upper surface of the pressure wall 5. Thus, the outer peripheral housing part 40 and the inner peripheral housing part 6 are connected. At this time, a method of disposing a seal member between the end portion 42 of the outer casing portion 40 and the lower surface of the flange portion 6c or forming a joint portion where the end portion 42 and the flange portion 6c are welded is formed. It may be adopted.

  In this case, regardless of the arrangement of the cryogenic fluid pump 100, it is possible to form a gap in which no low-temperature fluid exists between the inner peripheral housing portion 6 and the outer peripheral housing portion 40.

  Although the embodiment of the present invention has been described above, the above-described embodiment can be variously modified. The scope of the present invention is not limited to the above-described embodiment. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The present invention can be applied to a pump and a transfer device for transferring a low-temperature fluid used for cooling a superconducting device.

  DESCRIPTION OF SYMBOLS 1 Low temperature fluid transfer apparatus, 2 container, 3 inflow part, 4 outflow part, 5 pressure wall, 5a through-hole, 5b outer peripheral surface, 6 inner peripheral side housing | casing part, 6a inflow port, 6b outflow port, 6c flange part, 6d Impeller shaft cover, 6e Impeller cover, 7 Second housing, 8 Impeller, 9 First shaft, 10 Impeller shaft, 11 Radial magnetic bearing, 12 Thrust magnetic bearing, 14 Fixing member, 18 Lid, 20 Magnetic coupling, 21 First 2 joint members, 22 1st joint member, 30 motor, 31 2nd shaft, 40 outer peripheral side housing portion, 41 space, 42 end, 43 first end, 100 cryogenic fluid pump, LG cryogenic fluid.

Claims (9)

Impeller,
A rotating shaft for rotationally driving the impeller;
An impeller shaft connecting the rotating shaft and the impeller; and
A housing that holds the rotating shaft inside;
A magnetic bearing that rotatably supports the rotating shaft with respect to the housing;
The impeller shaft is a hollow cylinder and is a cryogenic fluid pump. The housing includes an inner circumferential housing portion to which the magnetic bearing is connected;
2. The cryogenic fluid pump according to claim 1, wherein the pump is for covering the inner peripheral housing portion from the outside, and includes the outer peripheral housing portion and the outer peripheral housing portion arranged with a gap. The outer peripheral housing portion is hermetically connected to the impeller side first end portion in the inner peripheral housing portion, and is located on the opposite side of the first end portion in the inner peripheral housing portion. The second end portion is arranged with a space therebetween,
The cryogenic fluid pump according to claim 2, wherein the gap is connected to the outside of the outer casing part through the space.   The cryogenic fluid pump according to claim 2, wherein the inner peripheral housing portion and the outer peripheral housing portion are connected so as to hermetically seal the gap.   The cryogenic fluid pump according to claim 4, wherein the gap is in a vacuum.   The pump for low-temperature fluid according to any one of claims 2 to 5, wherein the inner peripheral housing portion is made of any one of a stainless alloy and a resin material.   The pump for cryogenic fluid according to any one of claims 1 to 6, wherein the impeller shaft is made of any one of a stainless alloy and a resin material. The rotating shaft includes a first shaft connected to the impeller shaft, and a second shaft coupled to the first shaft in a non-contact manner by a magnetic coupling,
8. The cryogenic fluid pump according to claim 1, wherein the magnetic bearing supports the first shaft so as to be rotatable with respect to the housing. 9. A container containing a cryogenic fluid;
The cryogenic fluid pump according to any one of claims 1 to 8, which is installed in the container so that the impeller is disposed inside the container.
A cryogenic fluid transfer apparatus, comprising: a circulation pipe connected to the container and configured to circulate the cryogenic fluid to which kinetic energy is applied by the cryogenic fluid pump.

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