JP5458072B2 - Low temperature liquefied gas pump - Google Patents

Description

  The present invention relates to a low-temperature liquefied gas pump, and more particularly, to a low-temperature liquefied gas pump for feeding a low-temperature liquefied gas of −100 ° C. or lower such as liquid nitrogen.

  As a pump for taking out and sending various liquids stored in a container (tank), a drive unit arranged outside the container, a pump unit arranged in the container (in liquid), a drive unit and a pump unit A pump comprising a vertical shaft to be connected and a casing for supporting the shaft via a rolling bearing, wherein the shaft is divided into upper and lower parts, and the upper and lower divided shafts are magnetically coupled by a magnetic coupling (magnet coupling). An apparatus is known (for example, refer to Patent Document 1).

JP 2003-269375 A

  In the pump device described in Patent Document 1, since a rolling bearing such as a ball bearing is used as the shaft bearing, maintenance of the bearing is necessary every certain period, which is almost a problem in a general use state. However, it could not be used as a pump for high-temperature superconducting equipment that requires long-term continuous operation.

  In addition, it is possible to increase the heat insulation performance of the shaft by lengthening the shaft or increasing the number of divisions of the shaft, and it can be used as a pump for sending low temperature liquefied gas of -100 ° C or lower. When the low-temperature liquefied gas that has entered the casing through the gap between the bearings supporting the impellers in the casing is vaporized in the casing, the low-temperature liquefied gas flows back from the gap between the bearings to the impeller due to the pressure of the vaporized gas, and is sent by this reverse flow. Pulsation may occur in the low-temperature liquefied gas in the liquid.

  Therefore, an object of the present invention is to provide a low-temperature liquefied gas pump that can be operated continuously for a long period of time, can prevent pulsation, and can send a low-temperature liquefied gas in a stable state.

In order to achieve the above object, a low-temperature liquefied gas pump of the present invention includes a drive unit disposed outside a low-temperature liquefied gas container, a pump unit disposed inside a low-temperature liquefied gas container, an impeller of the pump unit, In a low-temperature liquefied gas pump comprising a shaft that connects a drive shaft of a drive unit and a casing that rotatably accommodates the shaft via a bearing, the drive shaft that is rotationally driven by the drive unit; A driven side shaft coupled to the impeller, and the drive side shaft and the driven side shaft are magnetically coupled in a non-contact state by a magnetic coupling, and at least the driven side shaft is connected via a magnetic bearing. thereby rotatably supported by the casing in a non-contact state, the lower end of the casing, said low-temperature liquefied gas container within the casing It is characterized in that a communication hole which communicates with.

  Further, in the low-temperature liquefied gas pump of the present invention, the diameter of the communication hole is in the range of 1 to 5 mm, and the magnetic coupling is provided between the drive-side shaft and the driven-side shaft, A partition member for partitioning the pump part side space is provided.

  According to the low-temperature liquefied gas pump of the present invention, since the shaft bearing is a magnetic bearing that does not require maintenance, continuous operation over a long period of time is possible. In addition, because the casing has a communication hole, even if the low-temperature liquefied gas that has entered the casing is vaporized, it does not flow back to the impeller side and is discharged from the communication hole. Can be prevented.

It is sectional drawing which shows the 1st form example of the low-temperature liquefied gas pump of this invention. It is sectional drawing which shows the 2nd form example of the low-temperature liquefied gas pump of this invention.

  The low-temperature liquefied gas pump 10 shown in FIG. 1 is mounted on the top plate member or the lid member 11a of the low-temperature liquefied gas container 11 storing the low-temperature liquefied gas L, and is disposed outside the low-temperature liquefied gas container 11. The drive unit 12, the pump unit 13 disposed in the low temperature liquefied gas inside the low temperature liquefied gas container 11, the impeller 14 of the pump unit 13 disposed in the low temperature unit, and the normal temperature unit are disposed. A shaft 16 that connects the drive shaft 15 of the drive unit 12 and a cylindrical casing 19 that rotatably accommodates the shaft 16 via a thrust magnetic bearing 17 and a radial magnetic bearing 18 are provided.

  The shaft 16 is divided into a driving-side upper shaft (motor shaft) 16a integrated with the driving shaft 15 and a driven-side lower shaft (pump shaft) 16b having the impeller 14 attached to the lower end thereof. The upper shaft 16a and the lower shaft 16b are magnetically coupled by a magnetic coupling (magnet coupling) 20 in a non-contact state.

  The magnetic coupling 20 has a cup-shaped drive side joint member 20a having an open bottom, an outer diameter smaller than the inner diameter of the drive side joint member 20a, and an inverted cup-shaped partition member inside the drive side joint member 20a. The cylindrical driven side coupling member 20b disposed via 21 is arranged concentrically, and the permanent magnets 22a and 22b are disposed on the inner circumferential surface of the driving side coupling member 20a and the outer circumferential surface of the driven side coupling member 20b. N poles and S poles are alternately arranged, and the rotation of the driving side coupling member 20a that rotates integrally with the upper shaft 16a is transmitted to the driven side coupling member 20b by the magnetic force of the permanent magnets 22a and 22b. Thus, the lower shaft 16b is rotated while keeping the upper shaft 16a and the lower shaft 16b in a non-contact state.

  The thrust magnetic bearing 17 provided on the upper portion of the lower shaft 16b is provided on the outer periphery of the lower shaft 16b and the pair of upper and lower electromagnets 17a and 17a fixed to the inner periphery of the casing 19 and arranged opposite to each other in the axial direction of the shaft. And a thrust plate 17b disposed between the upper and lower electromagnets 17a, 17a, and the magnetic force generated by the electromagnets 17a, 17a attracts the thrust plate 17b made of a magnetic material to each other so that the attracting force of the electromagnets 17a, 17a The thrust plate 17b in a balanced position is held in a non-contact state, and the movement in the axial direction of the lower shaft 16b including the impeller 14 is restricted.

  Further, the radial magnetic bearing 18 provided in each of the intermediate portion and the lower end portion of the lower shaft 16b is provided with a plurality of electromagnets 18a in a ring shape on the inner periphery of the casing 19 so as to surround the lower shaft 16b. The radial motion of the lower shaft 16b is regulated in a non-contact state by the magnetic force generated in the electromagnet 18a.

  The casing 19 has a cylindrical portion 19a inserted into the cryogenic liquefied gas container 11, and an upper flange 19b provided at the upper end of the cylindrical portion 19a. From the opening provided in the lid member 11a, the cylindrical portion In a state where 19a is inserted into the low temperature liquefied gas container 11, the upper flange 19b is fixed to the outer surface of the lid member 11a. In addition, a motor serving as the drive unit 12 is attached to the upper surface of the upper flange 19b via a support cylinder 23. A pump casing 25 that houses the impeller 14 of the pump portion 13 is connected to the lower end of the cylindrical portion 19a via a shaft insertion member 24, and a suction port 25a is provided at the lower portion of the pump casing 25 at the outer peripheral portion. Each is provided with a discharge port 25b.

  Furthermore, a communication hole 26 is provided at the lower end of the cylindrical portion 19a to allow communication between the inside of the casing 19 and the inside of the low-temperature liquefied gas container 11. If the diameter of the communication hole 26 is too small, the function as the communication hole cannot be obtained sufficiently. If the diameter is too large, the low-temperature liquefied gas boosted by the impeller 14 may escape from the communication hole 26, so It is preferable to set the range.

  In the low-temperature liquefied gas pump 10 formed in this way, the bearings that rotatably support the lower shaft 16b are magnetic bearings 17 and 18 that support the shaft in a non-contact state, so there are no wear parts and no maintenance is required. Yes, it can handle long-term continuous operation. Further, foreign matters are not generated in the bearing portion, and foreign matters can be prevented from being mixed into the low-temperature liquefied gas.

  Further, since the upper shaft 16a and the lower shaft 16b are magnetically coupled in a non-contact state by the magnetic coupling 20, heat penetration through the shaft can be suppressed. Thereby, since the shaft can be shortened, the natural frequency of the shaft can be increased and the shaft can be rotated at a high speed, and the impeller 14 can be rotated at a high speed to improve the liquid feeding efficiency.

  Further, the driven joint member 20b provided at the upper end of the lower shaft 16b is covered with a partition member 21, and the normal temperature space on the drive unit 12 side and the low temperature space on the pump unit 13 side are separated by the magnetic joint 20 portion. 21 is airtightly partitioned by the air inlet 21 so that outside air can be prevented from flowing into the low temperature liquefied gas container 11 and gas vaporized in the low temperature liquefied gas container 11 can be prevented from flowing to the outside. Can be reliably prevented from entering the low-temperature liquefied gas container 11. As a result, the quality of the low-temperature liquefied gas can be maintained, and the consumption of the low-temperature liquefied gas can be suppressed. Moreover, since it is not necessary to make the drive part 12 an airtight structure, a general-purpose motor can be used as a drive source of the drive part 12.

  Since the communication hole 26 is provided in the cylindrical portion 19a of the casing 19, even if the low-temperature liquefied gas that has entered the casing 19 is vaporized and the pressure in the casing 19 is increased, the low-temperature liquefied gas in the casing 19 is increased. Or the vaporized gas can be discharged from the communication hole 26, and the low-temperature liquefied gas or vaporized gas does not flow back into the pump casing 25 from between the shaft insertion member 24 and the lower shaft 16b, and is sent by the rotating impeller 14. Pulsation can be prevented from occurring in the liquefied low-temperature liquefied gas.

  This makes it possible to continuously feed a low-temperature liquefied gas such as liquid nitrogen of −100 ° C. or less that is easy to vaporize in a stable state over a long period of time, and thus a high-temperature superconducting device that requires long-term continuous operation It is optimal as a pump for circulating subcooled liquid nitrogen for cooling.

  FIG. 2 shows a second embodiment of the low temperature liquefied gas pump of the present invention. In the following description, the same components as those of the low-temperature liquefied gas pump shown in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the low-temperature liquefied gas pump shown in this embodiment, the magnetic coupling 30 includes a drive-side disc member 30a provided at the lower end of the upper shaft 16a and a driven-side disc member 30b provided at the upper end of the lower shaft 16b in an inverted cup shape. The structure is such that the N poles and S poles of the permanent magnets 31a and 31b are alternately arranged on the opposing surfaces of both the disk members 30a and 30b, while being opposed to each other via the upper surface of the partition member 21. Similarly to the above, this magnetic coupling 30 also transmits the rotation of the driving disk member 30a that rotates integrally with the upper shaft 16a to the driven disk member 30b by the magnetic force of the permanent magnets 31a and 31b, and rotates the lower shaft 16b. .

  Further, in the magnetic coupling 30 having such a structure, the driven-side disc member 30b is attracted to the upper drive-side disc member 30a side by the magnetic force of the permanent magnets 31a, 31b, so that the thrust magnetic bearing provided on the upper portion of the lower shaft 16b. 32, an electromagnet 32a for pulling the driven-side disk member 30b downward is arranged below the driven-side disk member 30b. The pulling force of the driven-side disk member 30b by the electromagnet 32a and the permanent magnet 31a in the magnetic coupling 30 are arranged. , 31b holds the driven disk member 30b in a non-contact state and regulates the movement of the lower shaft 16b including the impeller 14 in the axial direction.

  Therefore, the magnet as the thrust magnetic bearing 32 can be only the electromagnet 32a below the driven disk member 30b, and the magnet above the driven disk member 30b can be omitted, thus simplifying the pump structure. Can be planned.

  In addition, each magnetic bearing can also be provided in three or more places according to the length of a shaft. Further, the shaft can be divided into three or more and each can be formed to be supported by a plurality of magnetic bearings. Moreover, although the position and the number of the communication holes provided in the casing are arbitrary, it is preferable to provide at least one at the lowermost end portion of the casing in consideration of discharging the low-temperature liquefied gas from the casing.

  DESCRIPTION OF SYMBOLS 10 ... Low temperature liquefied gas pump, 11 ... Low temperature liquefied gas container, 11a ... Lid member, 12 ... Drive part, 13 ... Pump part, 14 ... Impeller, 15 ... Drive shaft, 16 ... Shaft, 16a ... Upper shaft, 16b ... Lower shaft 17 ... Thrust magnetic bearing, 17a ... Electromagnet, 17b ... Thrust plate, 18 ... Radial magnetic bearing, 18a ... Electromagnet, 19 ... Casing, 19a ... Cylindrical part, 19b ... Upper flange, 20 ... Magnetic joint, 20a ... Drive side joint Member, 20b ... driven side coupling member, 21 ... partition member, 22a, 22b ... permanent magnet, 23 ... support cylinder, 24 ... shaft insertion member, 25 ... pump casing, 25a ... suction port, 25b ... discharge port, 26 ... communication Hole 30, magnetic coupling, 30 a, drive side disk member, 30 b, driven side disk member, 31 a, 31 b, permanent magnet, 32, thrust magnetic shaft , 32a ... electromagnet, L ... low-temperature liquefied gas

Claims (3)

A drive unit disposed outside the cryogenic liquefied gas container, a pump unit disposed inside the cryogenic liquefied gas container, a shaft connecting the impeller of the pump unit and the drive shaft of the drive unit, and the shaft In a low-temperature liquefied gas pump including a casing that is rotatably accommodated via a bearing, the shaft is divided into a drive-side shaft that is rotationally driven by the drive unit and a driven-side shaft that is connected to the impeller. The drive side shaft and the driven side shaft are magnetically coupled in a non-contact state by a magnetic coupling, and at least the driven side shaft is rotatably supported by the casing in a non-contact state via a magnetic bearing, and The low-temperature liquefied gas pump which provided the communicating hole which connects the inside of this casing and the said low-temperature liquefied gas container in the lower end part of the casing. The low-temperature liquefied gas pump according to claim 1, wherein the diameter of the communication hole is within a range of 1 to 5 mm. 3. The low-temperature liquefied gas pump according to claim 1, wherein the magnetic coupling includes a partition member that partitions the drive unit side space and the pump unit side space between the drive side shaft and the driven side shaft.

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