CN105987530B - Low refrigerant system - Google Patents

Abstract

The present invention discloses a low refrigerant system comprising a low refrigerant magnet, a cryogenic refrigerator including a recondenser, a heat shield for thermally shielding the low refrigerant magnet, a liquid storage device, a gas storage device and a suspension device, Wherein, the liquid storage device is located in the heat shield and is in fluid communication with the recondenser for cooling the low refrigerant magnet, the gas storage device is located in the heat shield and is in fluid communication with the recondenser, and the suspension device has a A heat shield and a plurality of supports for the gas storage device, each support being a rigid member with low thermal conductivity. The suspension arrangement of the present invention provides a better connection between the gas storage device and the heat shield, and when the low refrigerant magnet cools down rapidly, the suspension arrangement of the present invention accommodates a lower gap between the heat shield and the gas storage device. Large differential thermal shrinkage, and can minimize differential thermal stress.

Description

low refrigerant system

technical field

The present invention relates generally to cooling systems, and more particularly to a low cryogen system for cooling low cryogen magnets.

Background technique

A cooling system is used to cool the low refrigerant magnets to cryogenic temperatures. An existing cooling system for a low-refrigerant magnet includes a cryogenic refrigerator, a heat shield for thermally isolating the low-refrigerant magnet from ambient temperature, and an air receiver located in the heat shield The hood and is used to store helium to supply the recondenser of the cryogenic refrigerator. In this existing cooling system, the gas storage tank is usually welded directly to the heat shield for thermally coupling the gas storage tank and the heat shield. However, since the gas storage tank is usually made of stainless steel, and the heat shield is usually made of aluminum material, the gas storage tank is not easily welded to the heat shield due to the difference in materials.

Therefore, there is a need for an improved system that addresses at least one of the problems described above.

Contents of the invention

An aspect of the present invention is to provide a low refrigerant system comprising a low refrigerant magnet, a cryogenic refrigerator including a recondenser, a heat shield for thermally shielding the low refrigerant magnet, a liquid storage device, a gas storage device and a suspension device, wherein the liquid storage device is located within the heat shield and is in fluid communication with the recondenser for cooling the low refrigerant magnet, the gas storage device is located in the Within the heat shield and in fluid communication with the recondenser, the suspension arrangement has a plurality of brackets for connecting the heat shield to the gas storage device, each of the brackets being of low thermal conductivity Sexual rigid components.

The low refrigerant system according to the specific embodiment of the present invention can better connect the gas storage device and the heat shield, and when the low refrigerant magnet cools down rapidly, the low refrigerant system according to the specific embodiment of the present invention can adapt to the Large differential thermal shrinkage between the heat shield and the gas storage device and minimizes differential thermal stress.

Description of drawings

These and other features, aspects and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings, in which like reference numerals are used to refer to like parts throughout, wherein :

1 is a schematic block diagram of a low refrigerant system according to a specific embodiment of the present invention;

Fig. 2 is a partial perspective assembly view of the heat shield and the gas storage device, and schematically shows a bracket for connecting the gas storage device and the heat shield according to the first embodiment of the present invention;

Fig. 3 is a three-dimensional exploded view of the flange of the heat shield of Fig. 2 and the gas storage device with the bracket;

4 schematically shows a partial cross-sectional view of connecting the flange of the heat shield to the gas storage device by means of a bracket according to a first embodiment of the present invention;

Figure 5 shows a simplified schematic diagram of the connection of the flange of the heat shield to the gas storage device by means of a bracket according to a second embodiment of the invention; and

6 and 7 schematically show the installation steps of the bracket in FIG. 5 .

Detailed ways

In order to help those skilled in the art to accurately understand the claimed subject matter of the present invention, the specific implementation manners of the present invention will be described in detail below in conjunction with the accompanying drawings. In the following detailed descriptions of these specific embodiments, this specification does not describe some well-known functions or structures in detail to avoid unnecessary details affecting the disclosure of the present invention.

Unless otherwise defined, the technical terms or scientific terms used in the claims and the description shall have the ordinary meanings understood by those skilled in the technical field to which the present invention belongs. "First", "second" and similar words used in the specification and claims do not indicate any sequence, quantity or importance, but are only used to distinguish different components. "A" or "one" and similar words do not indicate a limitation of number, but mean that there is at least one. Words such as "comprising" or "having" and similar terms mean that the elements or objects appearing before "comprising" or "having" include the elements or objects listed after "comprising" or "having" and their equivalent elements, and do not exclude other components or objects. Words such as "connected" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

Fig. 1 shows a schematic block diagram of a low refrigerant system according to a specific embodiment of the present invention. As shown in FIG. 1 , a low refrigerant system 100 according to a specific embodiment of the present invention includes a low refrigerant magnet 1 , a cryogenic refrigerator 2 including a recondenser 20 , and a heat shield for thermally shielding the low refrigerant magnet 1 . The shield 3, the liquid storage device 4, the gas storage device 5 and the suspension device 6, wherein the liquid storage device 4 is located in the heat shield 3 and is in fluid communication with the recondenser 20 for cooling the low refrigerant magnet 1, the gas The storage device 5 is located in the heat shield 3 and is in fluid communication with the recondenser 20 , and the suspension device 6 is used to connect the heat shield 3 and the gas storage device 5 .

Via the suspension device 6 of the present invention, the protective heat shield 3 and the gas storage device 5 are thermally coupled to each other. The suspension arrangement 6 of the present invention enables the heat shield 3 to cool the gas storage device 5 during cooling from room temperature. By providing suspension means 6 the gas storage means 5 will not heat up rapidly in the event of a power outage in order to maintain low pressure and prolong the operation of the low refrigerant magnet 1 .

Continuing to refer to FIG. 1 , the low refrigerant magnet 1 includes at least one coil support shell 12 and a plurality of magnet coils 14 . A plurality of magnet coils 14 are supported and positioned by at least one coil support case 12 . The coil support case 12 is formed of a thermally conductive material such as aluminum. A plurality of cooling tubes 10, which may be formed from any suitable metal (eg, copper, stainless steel, aluminum, etc.), are thermally coupled to at least one coil support housing 12 and are in fluid communication with liquid storage device 4 .

In a specific embodiment, the liquid storage device 4 may be, for example, a liquid helium storage device, and the liquid helium storage device may be composed of one or more liquid helium storage tanks. Fluid communication between the recondenser 20 and the liquid storage device 4 may be via one or more passages 91 . The liquid storage device 4 has a refrigerant inlet 42 for supplying a liquid refrigerant such as liquid helium (He). The refrigerant inlet 42 is provided with a hermetically sealed arrangement forming a closed loop cooling system. The liquid storage 4 contains liquid He for the closed loop cooling system to cool the magnet coils 14 . Between the plurality of cooling tubes 10 and the liquid storage device 4 , fluid communication may be achieved via one or more fluid passages 92 . Accordingly, the liquid He supplied from the liquid storage device 4 flows through the cooling pipe 10 to cool the magnet coil 14 .

Referring to FIG. 1 , in one embodiment of the invention, a low refrigerant system 100 is shown in a two-stage cooling arrangement. The cryogenic refrigerator 2 has two stages of different temperatures.

In a specific embodiment, the gas storage device 5 may be, for example, a helium storage device, and the helium storage device may consist of one or more helium tanks. Between the recondenser 20 and the helium storage device 5 fluid communication may be via one or more passages 94 . The plurality of cooling tubes 10 is also in fluid communication with a vapor return manifold 93 which is in fluid communication with the gas storage device 5 through the recondenser 20 . The gas storage device 5 contains He gas received from the cooling tube 10 as a He vapor to remove heat from the magnet coils 14 and form part of a closed loop cooling system.

A recondenser 20 is connected to the second stage of the cryogenic refrigerator 2 . The recondenser 20 draws He gas from the gas storage device 5 and operates to form a free convection circulation loop to cool the magnet coils 14 and coil support housing 12 to cryogenic temperatures while filling with liquid He via one or more passages 91 Liquid storage device 4. The liquid He in the liquid storage device 4 can be used to cool the magnet coils 14 during a power outage or shutdown of the cryogenic refrigerator 2, such as during a warranty period (eg, within 10 to 12 hours).

A heat shield 3 is connected to the first stage of the cryogenic refrigerator 2 . The heat shield 3 can be in thermal contact with the gas storage device 5 via the suspension device 6 . The heat shield 3 is thermally coupled to a plurality of cooling tubes 30 (eg, pre-cooling tubes) that are distinct from and not in fluid communication with the cooling tubes 10 . For example, the cooling tube 10 uses He for cooling, while the cooling tube 30 can use liquid nitrogen (LN ₂ ) for cooling or pre-cooling.

In the low refrigerant system 100 of the present invention with a two-stage cooling arrangement, cooling through the heat shield 3 can achieve the first stage cooling at a temperature of about 40-50K by contacting the first stage of the cryogenic refrigerator 2 , and pre-cooling may also be provided eg using LN ₂ at a temperature between about 77K and 80K. The second stage of cooling is achieved using He cooling to achieve an operating temperature of about 4.2K. However, the low refrigerant system 100 of the present invention should not be limited thereto. In one aspect, the low refrigerant system 100 of the present invention can be adapted to any multi-stage cooling arrangement.

The low refrigerant system 100 of the present invention is positioned within the vacuum vessel 8 . The cryogenic refrigerator 2 includes a cold head (not shown), a motor 22 for driving the cold head to work, and a cold head sleeve (not shown). The cold head of the cryogenic refrigerator 2 can be positioned in the cold head sleeve so as not to affect the vacuum in the vacuum container 8 . In addition, the motor 22 of the cryogenic refrigerator 2 is provided outside the vacuum vessel 8 .

2-4 show schematic diagrams of the connection between the heat shield 3 and the gas storage device 5 according to a first embodiment of the invention. FIG. 2 shows a partial perspective assembly view of the heat shield 3 and the gas storage device 5 . In Fig. 2, parts of the heat shield 3 and the gas storage device 5 are cut away in order to clearly show the individual components. As shown in FIG. 2 , the heat shield 3 includes a pair of flanges 31 , an outer cylinder 32 and an inner cylinder 34 . The outer cylinder 32 is positioned between the pair of flanges 31 . The inner cylinder 34 is in the middle of the heat shield 3 and extends through the pair of flanges 31 . The outer cylinder 32 is disposed around the inner cylinder 34 . In this detailed description, as a specific example, the gas storage device 5 is shown as comprising a pair of helium gas tanks. However, the gas storage device 5 of the present invention should not be limited thereto. In a specific embodiment of the invention, the heat shield 3 is made of aluminum and the gas storage device 5 is made of stainless steel.

FIG. 3 is an exploded perspective view of the flange 31 and the gas storage device 5 of the heat shield 3 of FIG. 2 . Referring to FIG. 2 and FIG. 3 , the suspension device 6 of the present invention includes a plurality of brackets 61 for connecting the heat shield 3 and the gas storage device 5 . Each bracket 61 is a rigid member with low thermal conductivity. In a specific embodiment, each bracket 61 has a thin-walled structure. For example, the pair of brackets 61 are typically made of thin-walled stainless steel.

In this specific embodiment, the gas storage device 5 is an annular gas storage device, and the gas storage device 5 is arranged around the inner cylinder 34 of the heat shield 3 . A plurality of brackets 61 are arranged along the circumferential direction of the gas storage device 5 and connected to the flange 31 of the heat shield 3 . In the drawings of the present invention, as a specific example, the plurality of brackets 61 are shown as six, and the six brackets 61 are equidistantly arranged on the gas storage device 5 along the circumferential direction of the annular gas storage device 5 . However, the number and distribution of the brackets 61 of the present invention should not be limited thereto, and the number and distribution of the brackets 61 of the present invention can be adjusted accordingly according to practical applications.

The plurality of brackets 61 are flexible in the radial direction of the plane where the gas storage device 5 is located, so that when the low refrigerant magnet 1 cools down rapidly, the plurality of brackets 61 can accommodate a relatively small gap between the heat shield 3 and the gas storage device 5. Large differential thermal shrinkage, and can minimize differential thermal stress. The plurality of brackets 61 are rigid in the axial direction and transverse direction of the plane where the gas storage device 5 is located, so the natural vibration frequency is high and will not adversely affect the imaging quality of the low-refrigerant system 100 . Furthermore, the plurality of racks 61 can also provide sufficient heat conduction through the heat shield 3 to cool the gas storage device 5 within a reasonable time.

FIG. 4 shows a partial sectional view of the connection of the flange 31 of the heat shield 3 to the gas storage device 5 by means of brackets 61 according to a first embodiment of the invention. As shown in FIGS. 3 and 4 with combined reference to FIG. 2 , each bracket 61 comprises a first bracket 611 connected to the gas storage device 5 and a second bracket 612 connected to the flange 31 of the heat shield 3 .

In the first embodiment of the present invention, the first bracket 611 and the second bracket 612 of each bracket 61 are two independent components, and the first bracket 611 and the second bracket 612 are connected to each other at a certain angle. The second bracket 612 is connected to the inner surface of the flange 31 of the heat shield 3 .

In a specific embodiment, the first bracket 611 and the second bracket 612 are made of the same material, and the first bracket 611 is welded to the second bracket 612 . For example, the first bracket 611 and the second bracket 612 are made of stainless steel.

Referring to FIGS. 3 and 4 , an opening 310 for facilitating connection between the first bracket 611 and the second bracket 612 is provided on the flange 31 . Through the opening 310, the first bracket 611 and the second bracket 612 can be welded together.

In this specific embodiment, the first bracket 611 and the second bracket 612 have the same material as the gas storage device 5, so the first bracket 611 can be connected to the gas storage device 5 by welding.

Because the first bracket 611 and the second bracket 612 have a different material from the heat shield 3 , the second bracket 612 cannot be directly welded to the heat shield 3 . In this case, as shown in FIGS. 3 and 4 , the flange 31 is provided with a plurality of holes 312 , and the second bracket 612 is also provided with a plurality of holes 6122 . In a specific embodiment, a plurality of rivets (not shown) can be riveted to the plurality of holes 312 on the flange 31 and the plurality of holes 6122 on the second bracket 612 from the inside or outside of the flange 31, so that The second bracket 612 is connected to the flange 31 . In another optional specific embodiment, a plurality of bolts (not shown) can be screwed to the plurality of holes 312 on the flange 31 and the plurality of bolts on the second bracket 612 from the inside or outside of the flange 31, respectively. A hole 6122 is provided to connect the second bracket 612 to the flange 31.

When assembling, first, the first bracket 611 of each bracket 61 can be welded to the gas storage device 5 , and the second bracket 612 can be connected to the flange 31 of the heat shield 3 by riveting or by bolts. Then, through the opening 310 of the flange 31 , the first bracket 611 and the second bracket 612 are welded together, so as to complete the assembly of all the brackets 61 of the suspension device 6 . Thus, the gas storage device 5 is connected to the heat shield 3 via the bracket 61 of the suspension device 6 .

The suspension device 6 comprising a plurality of brackets 61 of the present invention can rapidly cool the low-refrigerant magnet 1, and the suspension device 6 comprising a plurality of brackets 61 can maintain an almost constant air pressure, so that the low-refrigerant magnet 1 It can still run for a long time in the case of power failure, and the suspension device 6 including a plurality of brackets 61 can provide sufficient heat transfer by heat conduction to the heat shield 3 in a reasonable time to cool the gas storage device 5.

FIG. 5 shows a simplified schematic diagram of the connection of the flange 31 of the heat shield 3 to the gas storage device 5 by means of a bracket 62 according to a second embodiment of the invention. As shown in FIG. 5 , different from the bracket 61 in the first embodiment, in the second embodiment, the first bracket 621 and the second bracket 622 of the bracket 62 are integrally formed as a single-piece bracket, and, by pre-bending The brackets 62 are at an angle to each other.

Similar to the support 61 of the first embodiment, in the support 62 of the second embodiment, the first support 621 and the second support 622 also have the same material as the gas storage device 5, for example, the first support 621 and the second support The second bracket 622 is made of stainless steel. So the first bracket 621 can also be connected to the gas storage device 5 by welding.

Similar to the bracket 61 of the first embodiment, in the bracket 62 of the second embodiment, an opening 310 is also provided on the flange 31 of the heat shield 3 . But different from the bracket 61 of the first embodiment, in the bracket 62 of the second embodiment, the second bracket 622 extends through the opening 310 of the flange 31 to be connected to the outer surface of the flange 31 .

In addition, unlike the bracket 61 of the first embodiment, in the second embodiment, each bracket 62 further includes a block 623 , and the second bracket 622 is connected to the flange 31 through the block 623 . In a specific embodiment, the second bracket 622 is connected to the block 623 , and the block 623 is connected to the flange 31 . The block 623 has a different material from the first bracket 621 and the second bracket 622 , so the block 623 cannot be directly welded to the second bracket 622 . In a specific embodiment, a plurality of holes (not shown) are provided on both the second bracket 622 and the block 623 . The second bracket 622 may be connected to the block 623 by riveting or by bolts.

The block 623 has the same material as the heat shield 3, for example, the block 623 may be made of aluminum. Since the block 623 has the same material as the heat shield 3, the block 623 can be connected to the flange 31 of the heat shield 3 by welding.

In addition, in order to improve the uniformity of thermal conductivity between the second bracket 622 and the block 623 , a thermal interface (not shown) is provided between the second bracket 622 and the block 623 .

When assembling, referring to FIG. 6 , the first bracket 621 of each bracket 62 is respectively welded to the gas storage device 5 , and each bracket 62 is slid through the opening 310 of the flange 31 . Referring to FIG. 7 , then, the block 623 is screwed to the second bracket 622 of each bracket 62 . Next, referring to FIG. 5 , the flange 31 of the heat shield 3 is axially slid, and then the block 623 is welded to the flange 31 . Next, the second bracket 622 of each bracket 62 is separated from the mass 623, and the second bracket 622 is coated with a thermally conductive interface. Finally, the second bracket 622 is screwed down with thermal interface bonding. Thus, the assembly of all brackets 62 is completed, and the gas storage device 5 is connected to the flange 31 of the heat shield 3 through the suspension device 6 comprising a plurality of brackets 62 .

The suspension device 6 comprising multiple brackets 62 according to the second specific embodiment has beneficial technical effects similar to those of the multiple brackets 61 of the first specific embodiment, so details will not be repeated here.

Although the present invention has been described in detail in conjunction with specific embodiments, those skilled in the art can understand that many modifications and variations can be made to the present invention. It is, therefore, to be realized that the intent of the appended claims is to cover all such modifications and variations as are within the true spirit and scope of the invention.

Claims (12)

1. a kind of low refrigerant system comprising:

Low refrigerant magnet；

Cryo Refrigerator comprising after-condenser；

Solar heat protection shield is used for low refrigerant magnet described in heat shielding；

Fluid storage device is located in the solar heat protection shield and is in fluid communication with the after-condenser for cooling down the low system Cryogen magnet；

Gas storage device is located in the solar heat protection shield and is in fluid communication with the after-condenser；And

Draft hitch has multiple brackets for connecting the solar heat protection shield Yu the gas storage device, wherein each A bracket is the rigid member with low heat conductivity.

2. low refrigerant system as described in claim 1, wherein each described bracket has thin-wall construction.

3. low refrigerant system as described in claim 1, wherein the gas storage device is annular gas storage device, The multiple bracket is arranged along the circumferential direction of the annular gas storage device.

4. low refrigerant system as described in claim 1, wherein the solar heat protection shield includes flange, and the multiple bracket connects It is connected to the flange of the solar heat protection shield, each described bracket includes the first support for being connected to the gas storage device And it is connected to the second support of the flange of the solar heat protection shield.

5. low refrigerant system as claimed in claim 4, wherein the first support and the second support are two independences Component, also, the first support and the second support are connected to each other at an angle.

6. low refrigerant system as claimed in claim 5, wherein the second support is connected to the described of the solar heat protection shield The inner surface of flange is equipped on the flange for facilitating opening for the connection between the first support and the second support Mouthful.

7. low refrigerant system as claimed in claim 6, wherein the first support and the second support are by identical Material is made, also, the first support is welded to the second support, and the first support is connected by welding to the gas Body storage device is equipped with multiple holes on the flange and the second support, and the second support is by riveting or passes through It is bolted to the flange.

8. low refrigerant system as claimed in claim 4, wherein the first support and the second support are integrally formed as Single-piece bracket, also, the first support and the second support by bracket described in prebuckling each other at an angle.

9. low refrigerant system as claimed in claim 8, wherein be equipped with opening on the flange, the second support is prolonged The opening is extended through to be connected to the outer surface of the flange.

10. low refrigerant system as claimed in claim 9, wherein each described bracket further includes block, and described second Bracket is connected to the flange by the block, and the second support connects the block, and the block is connected to The flange.

11. low refrigerant system as claimed in claim 10, wherein the block has and the first support and described The different material of second support, the first support and the second support have material identical with the gas storage device Material, the block have material identical with the solar heat protection shield, and the first support is connected by welding to the gas Storage device, the second support is by riveting or is bolt-connected to the block, and the block is connected by welding It is connected to the flange.

12. low refrigerant system as claimed in claim 10, wherein be equipped between the second support and the block Thermally-conductive interface.