JPH058912U - Superconducting magnet cooling system - Google Patents

Abstract

(57) [Summary] [Purpose] To prevent a rapid increase in pressure in the refrigerant tank by suppressing the evaporation of the refrigerant when the superconducting magnet is quenched. A cooling device for a superconducting magnet, comprising a refrigerant tank 10 for accommodating a refrigerant 12, wherein a superconducting magnet 14 is immersed in the refrigerant 12.
A heat insulating material 24 is provided at a position covering at least a part of the surface of No. 4, leaving a gap between the heat insulating material and the surface.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

  The present invention relates to a device for cooling a superconducting magnet to a cryogenic temperature. It

[0002]

[Prior art]

  Generally, a superconducting magnet is cooled to a cryogenic temperature by a device as shown in FIG. It is used as it is. The refrigerant tank 110 shown in the figure is kept at a low temperature by a heat retention means (not shown). In the held state, the coolant 112 such as liquid helium is stored in the coolant tank 110. Has been done. Then, the cylindrical superconducting magnet 114 is immersed in the coolant 112. The superconducting magnet 114 is placed on the top of the lid 116 of the refrigerant tank 110. It is suspended and supported via several suspension bars 118. The lid 116 is steamed A gas outlet 120 is provided and a safety valve 122 is provided.

[0003]   In such a cooling device, in the vicinity of the surface of the superconducting magnet 114, as shown in FIG. The film boiling state as shown in (3) has occurred. That is, the table of the superconducting magnet 114 A gas film 124 formed by the vaporized refrigerant is formed on the surface, The gas becomes bubbles 126, passes through the liquid-phase refrigerant 112, and escapes upward. This evaporation The generated refrigerant gas is discharged to the outside of the system through the evaporative gas outlet 120. If the pressure in the tank 110 rises above a certain level, it will also be released from the safety valve 122. And

[0004]

[Problems to be solved by the device]

  The superconducting magnet 114 may be damaged by any cause of heat generation during its use. There is a case where the state is changed, that is, the superconducting state is changed to the normal conducting state. This If such a quench occurs while the superconducting magnet 114 is energized, the superconducting magnet 114 The electric resistance of the superconducting wire that constitutes 114 sharply increases, which causes Joule heat generation. Due to the rapid evaporation of the refrigerant, the pressure in the refrigerant tank 112 increases abnormally. A match occurs. Also, in order to cope with such a sudden pressure increase, a large diameter Since the safety valve 122 must be used, the cost increase cannot be avoided.

[0005]   In consideration of such a situation, the present invention provides a refrigerant when the superconducting magnet is quenched. By suppressing the evaporation of refrigerant, it is possible to prevent a sudden pressure increase in the refrigerant tank. An object of the present invention is to provide a cooling device for a conductive magnet.

[0006]

[Means for Solving the Problems]

  The present invention is provided with a coolant tank containing a coolant, in which the superconducting magnet is immersed. In the cooling device for the immersed superconducting magnet, If a heat insulating material is provided at a position that covers a part of it, leaving a gap between it and this surface (Claim 1).

[0007]   Furthermore, the heat insulating material covers the side surface of the superconducting magnet and opens the bottom surface. The shape of the heat insulating material is increased, and the opening area increases toward the lower end of this heat insulating material. The skirt part to be formed, and at the position inside or below this skirt part. By arranging the refrigerant inlet, more excellent effects as described below can be obtained (claim Item 2).

[0008]

[Action]

  In the above configuration, when the superconducting magnet is quenched, its Joule heat is generated. The refrigerant gas that evaporates due to it stays in the gap between the superconducting magnet and the heat insulating material and fills up. Therefore, a so-called gas layer is formed in the gap. That is, The gas layer and the heat insulating material are interposed between the magnet and the liquid refrigerant. Therefore, compared with the structure in which the superconducting magnet and the liquid phase refrigerant are adjacent to each other, the superconducting magnet The heat transfer from the refrigerant to the liquid-phase refrigerant is suppressed, and a sudden increase in pressure due to evaporation of the refrigerant is prevented. Be done. On the other hand, in the normal state where the quench does not occur, the Since the liquid-phase refrigerant penetrates into the heat insulating material, the superconducting magnet is the same as the conventional device. To be cooled.

[0009]   Further, according to claim 2, a skirt is provided at the lower end of the heat insulating material. According to the above, the evaporative gas of the refrigerant injected from the refrigerant inlet into the refrigerant tank during precooling is The superconducting magnet is collected on the surface of the superconducting magnet by the cart. Is effectively cooled.

[0010]

【Example】

  A first embodiment of the present invention will be described with reference to FIG.

[0011]   In the figure, 10 is a refrigerant tank, and this refrigerant tank 10 is a liquid nitrogen tank or vacuum not shown. It is housed in a cryogenic holding container consisting of a container. In the coolant tank 10, liquid A refrigerant 12 such as helium is contained, and a cylindrical superconducting magnet 14 is placed in the refrigerant 12. Is soaked. The superconducting magnet 14 is installed on the lid 16 of the refrigerant tank 10 as a cover. It is connected via a plurality of suspension rods 18 made of stainless steel, etc. Lowered and supported. Further, the lid 16 has an evaporative gas outlet 20 and a safety valve 22. Is provided.

[0012]   Further, as a feature of this device, the surrounding of the superconducting magnet 14 is A heat insulating material 24 is provided so as to cover the surface. This heat insulating material 24 is FRP , A bake plate or the like having a relatively low thermal conductivity, A top plate 24a that covers the upper surface from above and a bottom plate that covers the bottom surface of the superconducting magnet 14 from below. 24b and an outer plate 24c that covers the outer surface of the superconducting magnet 14 from the outer side in the radial direction. And the inner plate 24d that covers the inner surface of the superconducting magnet 14 from the inner side in the radial direction. It is joined to the body. The top plate 24a is provided for passing evaporative gas. A plurality of through holes 24e are provided, and the superconducting magnet 14 A through hole (not shown) for guiding the current lead wire is provided.

[0013]   Then, the suspension rod 18 is passed through an appropriate through hole of the through holes 24e. The upper surface and the outer side surface of the superconducting magnet 14 and the top plate 24a and the outer plate 24 in the closed state. By interposing an appropriate number of small-piece-shaped support spacers 23 with c, A predetermined gap is secured between the inner surface of 24a to 24d and the outer surface of the superconducting magnet 14. The entire heat insulating material 24 is supported in this state. Here, the superconducting magnet 14 When the outer diameter is 10 cm to 70 cm, the thickness of each of the plates 24a to 24d and the gap It is preferable that the dimension of a few mm to 1 cm. The support spacer 23 is a superconducting material. It may be fixed to the outer surface of the magnet 14 or fixed to the inner surface of the heat insulating material 24. You may do it.

[0014]   In such a cooling device, quenching does not occur in the superconducting magnet 14. In a normal state, liquid does not flow into the gap between the outer surface of the superconducting magnet 14 and the inner surface of the heat insulating material 24. Phase refrigerant 12 has invaded, which causes the superconducting magnet 14 to cool to an extremely low temperature. Will be rejected. On the other hand, near the surface of the superconducting magnet 14, film boiling as shown in FIG. Although a state has occurred, the refrigerant gas generated by this boiling forms bubbles in the through hole 24e. And then discharged to the outside of the system through the evaporative gas outlet 20. Also, in the refrigerant tank 10 When the pressure of the pressure rises above a certain level, the vaporized gas is also released from the safety valve 22.

[0015]   On the other hand, the superconducting magnet 14 is quenched due to some cause of heat generation. If it occurs, a large increase in the resistance will cause a large Joule heat generation. The evaporation of the refrigerant 12 near the surface of the conductive magnet 14 is promoted. However Since the superconducting magnet 14 is covered with the heat insulating material 24, the gap between the two is not present. The evaporated gas of the refrigerant 12 stays and fills, forming a so-called gas layer. sand That is, the gas layer and the heat insulating material are provided between the superconducting magnet 14 and the liquid-phase refrigerant 12. Since 24 is interposed, the superconducting magnet 14 and the liquid-phase refrigerant 12 are directly adjacent to each other. Heat transfer from the superconducting magnet 14 to the liquid-phase refrigerant 12 is suppressed compared to the conventional device Will be done. Therefore, even if the quench occurs, the liquid-phase refrigerant 12 is not rapidly Since it does not evaporate, the pressure in the refrigerant tank 12 is prevented from rising rapidly, and the safety valve 22 is also compared. It can be done on a small scale.

[0016]   The second embodiment is shown in FIG. Here, with the two members of the top plate 25 and the outer cylinder 26, A heat insulating material is formed, and only the upper surface and the outer surface of the superconducting magnet 14 are covered from the outside. It is in a broken state. Further, the top plate 25 has a through hole for passing the hanging rod 18. 25a is provided, and between the plates 25 and 26 and the superconducting magnet 14 is provided. The support spacers 23 are provided to secure the same clearance as in the first embodiment. It

[0017]   As described above, in the present invention, it is not necessary to cover the entire surface of the superconducting magnet 14, and By covering at least a part of the it can.

[0018]   A third embodiment is shown in FIG. Here, the top plate 25 is also omitted and the outer cylinder 26 The heat insulating material is composed of only the outer cylinder 26, and the outer cylinder 26 is hung by FRP or the like. The inner periphery of the outer cylinder 26 is suspended and supported by the lid 16 of the refrigerant tank 10 via a rod 28. A support spacer 23 is provided between the surface and the outer peripheral surface of the superconducting magnet 14. . As described above, in the present invention, regardless of the support structure of the heat insulating material, the heat insulating material is appropriately set according to its shape. You can set it.

[0019]   A fourth embodiment is shown in FIG. Here, at the lower end of the outer cylinder 26 of the third embodiment, , A skirt portion 27 whose opening area increases as it goes downward is formed. In addition, a through hole 27a is provided in a part of the skirt portion 27. And outside The refrigerant injection pipe 30 arranged outside the cylinder 26 is passed through the through hole 27a to form the skirt. The refrigerant injection pipe 30 is inserted into the inside of the portion 27, and the lower portion of the inside of the skirt portion 27 has the refrigerant injection pipe 30. A lower end refrigerant inlet 30a is provided. The coolant inlet 30a is a scar You may arrange | position in the position below the lower end of the toe part 27.

[0020]   In such a device, during the pre-cooling, the refrigerant injection port 30a is provided through the refrigerant injection pipe 30. When the refrigerant 12 is injected into the bottom of the refrigerant tank 12 from the It is gathered on the surface of the superconducting magnet 14 while being guided by the contact part 27, and is collected here. The superconducting magnet 14 is effectively pre-cooled because it flows in the middle.

[0021]   In the present invention, regardless of the specific shape of the superconducting magnet 14, The shape of the heat insulating material may be appropriately set accordingly. Regarding the support structure, In addition to the suspension type as shown in the embodiment, the superconducting magnet 14 is attached to the bottom surface of the refrigerant tank 10. It may be connected to and supported from below.

[0022]   In addition, the structure of the entire heat insulating material when the skirt portion 27 is provided is the same as that of the superconducting magnet. Any shape may be used as long as it covers the side surface of the hood 14 and opens the bottom surface. Is unquestioned.

[0023]

[Effect of device]

  As described above, according to the present invention, the superconducting magnet is immersed in the refrigerant contained in the refrigerant tank. In the cooling device for the superconducting magnet, the surface of the superconducting magnet A heat insulating material is provided at a position that covers at least a part, leaving a gap between this surface and Therefore, in the normal state where the superconducting magnet is not quenched, It is possible to cool the superconducting magnet in the same way as in the past with the refrigerant that enters. On the other hand, when the superconducting magnet is quenched, it evaporates due to its Joule heat generation. By allowing the refrigerant gas to stay in the gap, forming a so-called gas layer, It is possible to suppress heat transfer from the superconducting magnet to the surrounding liquid-phase refrigerant. Therefore, it is possible to suppress the evaporation rate of the refrigerant and prevent a rapid pressure increase in the refrigerant tank. effective.

[0024]   Furthermore, the heat insulating material covers the side surface of the superconducting magnet and opens the bottom surface. The shape of the heat insulating material is increased, and the opening area increases toward the lower end of this heat insulating material. Forming a skirt that has a coolant inlet in or below According to the above, the skirt collects the vaporized refrigerant gas injected from the refrigerant inlet. The effective flow of the superconducting magnet by intensively flowing it on the surface of the superconducting magnet. There is an effect that various pre-cooling can be performed.

[Brief description of drawings]

FIG. 1 is a sectional perspective view of a cooling device for a superconducting magnet according to a first embodiment of the present invention.

FIG. 2 is a sectional perspective view of a cooling device for a superconducting magnet according to a second embodiment of the present invention.

FIG. 3 is a sectional front view of a cooling device for a superconducting magnet according to a third embodiment of the present invention.

FIG. 4 is a sectional front view of a cooling device for a superconducting magnet according to a fourth embodiment of the present invention.

FIG. 5 is a sectional front view of a cooling device for a conventional superconducting magnet.

FIG. 6 is an explanatory diagram showing a film boiling state of a refrigerant on the surface of the superconducting magnet.

[Explanation of symbols]

10 Refrigerant tank 12 Refrigerant 14 Superconducting magnet 24 Thermal insulation 25 Top plate (constitutes heat insulating material) 26 Outer cylinder (constitutes heat insulating material) 27 Skirt 30a Refrigerant inlet

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Creator Masatoshi Yoshikawa             1-4-1 Migatadai, Nishi-ku, Kobe-shi             Dormitory Room 713

Claims (2)

[Scope of utility model registration request] 1. A cooling device for a superconducting magnet, comprising a refrigerant tank for accommodating a refrigerant, wherein the superconducting magnet is immersed in the refrigerant, at a position covering at least a part of the surface of the superconducting magnet, and between the surface and the surface. A cooling device for a superconducting magnet, characterized in that a heat insulating material is provided leaving a gap. 2. The cooling device for a superconducting magnet according to claim 1, wherein the heat insulating material is formed in such a shape as to cover a side surface of the superconducting magnet and open a bottom surface thereof, and extends downward to a lower end portion of the heat insulating material. A cooling device for a superconducting magnet, wherein a skirt portion having an opening area enlarged according to the above is formed, and a refrigerant inlet is arranged in or below the skirt portion.