Cryogenic cooling system and cryogenic cooling method

Abstract

Even if a malfunction occurs in the control valve that controls the flow rate of refrigerant to multiple superconducting coils, the superconducting coils can continue to be cooled. [Solution] In a cryogenic cooling system 50 in which a cryogenic refrigerator 12 and a plurality of high-temperature superconducting coils 11A, 11B are connected by a cooling pipe 13 that has branched pipe sections 14A, 14B corresponding to the high-temperature superconducting coils, and control valves 18A, 18B are provided in each branched pipe section, the flow rate of refrigerant flowing from the cryogenic refrigerator to the high-temperature superconducting coils is controlled by the control valves, thereby cooling the high-temperature superconducting coils, the plurality of high-temperature superconducting coils are thermally connected by a heat transfer member 51.

Description

Technical Field

[0001] Embodiments of the present invention relate to a cryogenic cooling system and a cryogenic cooling method.

Background Art

[0002] Generally, superconducting devices need to be cooled to cryogenic temperatures. In recent years, high-temperature superconductors and high-temperature superconducting magnets using them have been developed, and the cooling temperature has increased from near the conventional 4K to about 20K. In this temperature range, the power required for cooling generally decreases in approximate proportion to the absolute temperature, so that the application of high-temperature superconducting magnets to devices with a large heat load has become possible. As a result, a large refrigeration capacity is often required in the cooling system of high-temperature superconducting devices.

[0003] Also, since the cooling temperature is high, the conventional method using liquid helium is not suitable. For this reason, a method of cooling a high-temperature superconducting magnet by a conduction cooling method or a gas circulation method using a mechanical refrigerator is used. In particular, in a cooling system with a large heat load, in the conduction cooling method, there is a problem that the temperature difference between the refrigerator and the high-temperature superconducting magnet becomes large and the temperature of the high-temperature superconducting magnet becomes high, so the gas circulation cooling method is suitable.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] Here, as shown in Figure 7, we consider a large cryogenic cooling system 100 that uses multiple high-temperature superconducting magnets 101. In such a cryogenic cooling system 100, a cooling pipe 103 that circulates a gaseous refrigerant by a circulation pump 102 is branched to form a piping configuration with multiple parallel branch pipe sections 104, and each branch pipe section 104 is connected to a high-temperature superconducting magnet 101. However, such a piping configuration presents the problem of instability in the gaseous refrigerant flow.

[0006] This means that when a thermal load imbalance occurs in the high-temperature superconducting magnet 101 from the state shown in Figure 8(A) to the state shown in Figure 8(B) (the size of the arrow in the figure indicates the thermal load), the temperature of the branch piping section 104 connected to the high-temperature superconducting magnet 101 with a large thermal load rises. This temperature rise increases the pressure loss in the branch piping section 104, making it difficult for the gaseous refrigerant to flow, which in turn causes the temperature of the branch piping section 104 to rise further, creating a negative chain reaction. Therefore, a method is adopted in which control valves 105 are provided in each branch piping section 104 that are arranged in parallel to control the flow rate of the gaseous refrigerant flowing through each branch piping section 104. Note that reference numeral 106 in Figure 7 indicates a heat exchanger.

[0007] However, in the gas circulation type cryogenic cooling system 100 described above, there is a problem in that impurities in the circulating gas refrigerant accumulate on the control valve 105, causing the control valve 105 to become blocked. When the control valve 105 becomes blocked, it becomes difficult for the gas refrigerant to flow into the branch piping section 104 where the control valve 105 is located, causing the temperature of the high-temperature superconducting magnet 101 being cooled in this branch piping section 104 to rise and leading to a quench. Furthermore, even if the control valve 105 is not completely blocked, a significant increase in pressure loss can make it impossible to control the control valve 105, or a failure in the control system can also cause similar problems.

[0008] The embodiments of the present invention have been made in consideration of the above circumstances, and aim to provide a cryogenic cooling system and cryogenic cooling method that can continuously cool superconducting coils even if a malfunction such as blockage occurs in the control valve that controls the flow rate of refrigerant supplied to each of the multiple superconducting coils. [Means for solving the problem]

[0009] The cryogenic cooling system in the embodiment of the present invention is characterized in that a cryogenic refrigerator and a plurality of objects to be cooled are connected by cooling piping having a plurality of branched piping sections corresponding to the objects to be cooled, and a control valve is provided in each of the branched piping sections, and the objects to be cooled are cooled by controlling the flow rate of refrigerant flowing from the cryogenic refrigerator to the objects to be cooled by the control valve, and the plurality of objects to be cooled are thermally connected by heat transfer members.

[0010] The cryogenic cooling method in an embodiment of the present invention is characterized in that a refrigerant is flowed from a cryogenic refrigerator to a plurality of objects to be cooled via a plurality of branch pipe sections of a cooling pipe, and the flow rate of the refrigerant is controlled by control valves arranged in each of the branch pipe sections to cool the objects to be cooled, wherein the plurality of objects to be cooled are thermally connected by heat transfer members, and the objects to be cooled are cooled by heat conduction by the heat transfer members. [Effects of the Invention]

[0011] According to an embodiment of the present invention, even if a malfunction such as blockage occurs in the control valve that controls the flow rate of the refrigerant supplied to each of the multiple superconducting coils, the superconducting coils can be continuously cooled. [Brief explanation of the drawing]

[0012] [Figure 1] A piping diagram showing a cryogenic cooling system according to the first embodiment. [Figure 2] A piping diagram showing a portion of the cryogenic cooling system according to the second embodiment. [Figure 3] A piping diagram showing a portion of the cryogenic cooling system according to the third embodiment. [Figure 4] A piping diagram showing a portion of the cryogenic cooling system according to the fourth embodiment. [Figure 5]A piping diagram showing a portion of the cryogenic cooling system according to the fifth embodiment. [Figure 6] A piping diagram showing a portion of the cryogenic cooling system according to the sixth embodiment. [Figure 7] A piping diagram showing a conventional cryogenic cooling system. [Figure 8] This is a part of Figure 7, where (A) shows the case where the refrigerant flow rate in each branch piping section is equal, and (B) shows the case where the refrigerant flow rate in the branch piping section decreases due to an increase in the thermal load of the high-temperature superconducting coil. [Modes for carrying out the invention]

[0013] Hereinafter, embodiments for carrying out the present invention will be described based on the drawings. [A] First embodiment (Figure 1) Figure 1 is a piping diagram showing a cryogenic cooling system according to the first embodiment. The cryogenic cooling system 10 shown in Figure 1 cools a plurality of high-temperature superconducting coils (e.g., high-temperature superconducting coils 11A and 11B) as objects to be cooled using a gas circulation method, and comprises a cryogenic refrigerator 12, cooling piping 13 equipped with a plurality of branch piping sections (e.g., branch piping sections 14A and 14B), a circulation pump 15, heat exchangers 16 and 17, a plurality of control valves (e.g., control valves 18A and 18B), connecting piping 19 equipped with a connecting valve 20, a plurality of temperature measuring means (e.g., temperature measuring means 21A and 21B), and a control unit 22.

[0014] The cryogenic refrigerator 12 has a first cooling stage 12N and a second cooling stage 12M, and these first cooling stage 12N and second cooling stage 12M are connected in series to the cooling pipe 13. In addition, the branch pipe sections 14A and 14B of the cooling pipe 13 are arranged in parallel to correspond to multiple high-temperature superconducting coils 11A and 11B, and each is connected to the high-temperature superconducting coils 11A and 11B. In this way, the cryogenic refrigerator 12 and the high-temperature superconducting coils 11A and 11B are connected by the cooling pipe 13.

[0015] The circulation pump 15 circulates a gas refrigerant such as helium gas through the loop-shaped cooling pipe 13, and it may be a compressor, a blower, or the like. The gas refrigerant is sequentially fed by the circulation pump 15 to the first cooling stage 12N and the second cooling stage 12M of the cryogenic refrigerator 12 and cooled step by step.

[0016] The heat exchanger 16 is disposed in the cooling pipe 13, and cools the refrigerant flowing from the first cooling stage 12N to the second cooling stage 12M of the cryogenic refrigerator 12 by heat exchange with the gas refrigerant after cooling the high-temperature superconducting coils 11A and 11B. Further, the heat exchanger 17 is disposed in the cooling pipe 13, and cools the refrigerant flowing to the first cooling stage 12N of the cryogenic refrigerator 12 by heat exchange with the gas refrigerant flowing out from the heat exchanger 16.

[0017] Each of the control valves 18A and 18B is disposed in each of the branch pipe portions 14A and 14B of the cooling pipe 13. The gas refrigerant flowing through the cooling pipe 13 by the action of the circulation pump 15 and sequentially cooled step by step by the heat exchanger 17, the first cooling stage 12N of the cryogenic refrigerator 12, the heat exchanger 16, and the second cooling stage 12M of the cryogenic refrigerator 12 flows to the high-temperature superconducting coil 11A through the branch pipe portion 14A of the cooling pipe 13 and to the high-temperature superconducting coil 11B through the branch pipe portion 14B, and cools these high-temperature superconducting coils 11A and 11B. At this time, when there is an imbalance in the heat load in the high-temperature superconducting coils 11A and 11B, the control valves 18A and 18B perform flow rate control to preferably ensure the flow rate of the gas refrigerant flowing in the branch pipe portions 14A and 14B, and cool the high-temperature superconducting coils 11A and 11B well.

[0018] The connecting pipe 19 is a pipe that connects the downstream sides of the control valves 18A and 18B in the plurality of branch pipe portions 14A and 14B of the cooling pipe 13. For example, one connecting pipe 19 connects two of the plurality of branch pipe portions 14A and 14B on the downstream side of the control valves 18A and 18B.

[0019] The control unit 22 controls the opening degree of the connecting valve 20 located in the connecting pipe 19 based on temperature measurements from temperature measuring means 21A and 21B. Specifically, temperature measuring means 21A is installed on the high-temperature superconducting coil 11A to measure the temperature of the high-temperature superconducting coil 11A, and temperature measuring means 21B is installed on the high-temperature superconducting coil 11B to measure the temperature of the high-temperature superconducting coil 11B. The temperature measurements from these temperature measuring means 21A and 21B are input to the control unit 22.

[0020] The control unit 22 determines that a malfunction such as blockage has occurred in the control valve 18A or 18B that supplies gaseous refrigerant to the high-temperature superconducting coil 11A or 11B, to which the temperature measuring means 21A or 21B that measured the temperature has rapidly increased, i.e., the rate of change of the temperature measurement value exceeds a predetermined value. The control unit 22 then opens (fully opens) the connecting valve 20 provided in the connecting pipe 19 downstream of the malfunctioning control valve 18A or 18B.

[0021] In other words, the control unit 22 opens the connecting valve 20 of the connecting pipe 19 that connects the branch piping section 14A or 14B, where the flow of gas refrigerant is poor due to a malfunction of the control valve 18A or 18B, to the branch piping section 14B or 14A, where the flow of gas refrigerant is good. As a result, gas refrigerant is supplied from the branch piping section 14B or 14A, which has a good control valve 18B or 18A and a good flow of gas refrigerant, to the branch piping section 14A or 14B, which has a malfunctioning control valve 18A or 18B and a poor flow of gas refrigerant.

[0022] Furthermore, when the temperature readings from the temperature measuring means 21A and 21B exceed a predetermined value, the control unit 22 may open the connecting valve 20 provided in the connecting pipe 19 downstream of the control valve 18A or 18B, regardless of whether the control valve 18A or 18B that supplies gas refrigerant to the high-temperature superconducting coil 11A or 11B to which the temperature measuring means 21A or 21B that measured the temperature reading is installed is malfunctioning (e.g., blocked). This makes it possible to supply gas refrigerant to the high-temperature superconducting coil 11A or 11B to which the temperature readings exceed a predetermined value are installed, by diverting the gas from the branch piping section 14B or 14A equipped with another control valve 18B or 18A, via the opened connecting valve 20.

[0023] As configured as described above, the first embodiment provides the following effect (1). (1) In the cryogenic cooling system 10, gaseous refrigerant is flowed from the cryogenic refrigerator 12 through multiple branch pipe sections 14A and 14B of the cooling pipe 13 to multiple high-temperature superconducting coils 11A and 11B, and the flow rate of the gaseous refrigerant is controlled by control valves 18A and 18B installed in each branch pipe section 14A and 14B to cool the high-temperature superconducting coils 11A and 11B. Furthermore, in the cryogenic cooling system 10, the multiple branch pipe sections 14A and 14B are connected downstream of the control valves 18A and 18B by connecting pipes 19 equipped with connecting valves 20. Furthermore, if a malfunction occurs in the control valve 18A or 18B, a connecting valve 20 located in the connecting pipe 19 downstream of the malfunctioning control valve 18A or 18B is opened, and gaseous refrigerant is diverted from the branch piping section 14B or 14A equipped with a working control valve 18B or 18A to the branch piping section 14A or 14B equipped with the malfunctioning control valve 18A or 18B via this connecting valve 20. As a result, the high-temperature superconducting coils 11A and 11B can be continuously cooled.

[0024] [B] Second embodiment (Figure 2) Figure 2 is a piping diagram showing a part of the cryogenic cooling system according to the second embodiment. In this second embodiment, parts that are the same as in the first embodiment are denoted by the same reference numerals as in the first embodiment, and their explanation is simplified or omitted. Note that Figure 2 shows the configuration below the cryogenic refrigerator in the cryogenic cooling system shown in Figure 1.

[0025] The difference between the cryogenic cooling system 25 of this second embodiment and the first embodiment is that each of the multiple branch pipe sections (for example, branch pipe sections 14A, 14B) of the cooling pipe 13 is provided with multiple flow rate measuring means (for example, flow rate measuring means 26A, 26B) for measuring the flow rate of the gaseous refrigerant flowing inside, and the control unit 27 receives the flow rate measurements from each of the flow rate measuring means 26A, 26B and controls the opening degree of the connecting valve 20 provided on the connecting pipe 19.

[0026] In other words, when the flow rate measured by the flow rate measuring means 26A or 26B falls below a predetermined flow rate, the control unit 27 determines that a malfunction such as blockage has occurred in the control valve 18A or 18B located in the branch piping section 14A or 14B where the flow rate measuring means 26A or 26B that measured the flow rate is provided. The control unit 27 then opens (fully opens) the connecting valve 20 located in the connecting piping 19 downstream of the malfunctioning control valve 18A or 18B.

[0027] In other words, the control unit 27 opens the connecting valve 20 of the connecting pipe 19 that connects the branch piping section 14A or 14B, where the flow of gas refrigerant is poor due to a malfunction of the control valve 18A or 18B, to the branch piping section 14B or 14A, where the flow of gas refrigerant is good. As a result, gas refrigerant is supplied from the branch piping section 14B or 14A, which has a good control valve 18B or 18A and a good flow of gas refrigerant, to the branch piping section 14A or 14B, which has a malfunctioning control valve 18A or 18B and a poor flow of gas refrigerant, via the opened connecting valve 20.

[0028] As described above, in the second embodiment, the flow rate of the gaseous refrigerant flowing through the branch pipe sections 14A and 14B of the cooling pipe 13 that supplies gaseous refrigerant to the high-temperature superconducting coils 11A and 11B is measured to determine if there is a malfunction in the control valves 18A and 18B installed in these branch pipe sections 14A and 14B, and the system controls the opening of the connecting valve 20 provided in the connecting pipe 19 downstream of the malfunctioning control valve 18A or 18B. Therefore, in the second embodiment as well, the high-temperature superconducting coils 11A and 11B can be continuously cooled, similar to the effect (1) of the first embodiment.

[0029] [C] Third embodiment (Figure 3) Figure 3 is a piping diagram showing a part of the cryogenic cooling system according to the third embodiment. In this third embodiment, parts that are the same as in the first embodiment are denoted by the same reference numerals as in the first embodiment, and their explanation is simplified or omitted. Note that Figure 3 shows the configuration below the cryogenic refrigerator in the cryogenic cooling system shown in Figure 1.

[0030] The difference between the cryogenic cooling system 30 of this third embodiment and the first embodiment is that the downstream sides of the control valves 18A and 18B in multiple branch pipe sections (for example, branch pipe sections 14A and 14B) of the cooling pipe 13 are connected by connecting pipes 31 and 32, and a differential pressure driven valve 33 is installed in the connecting pipe 31 and a differential pressure driven valve 34 is installed in the connecting pipe 32 as connecting valves.

[0031] The differential pressure driven valves 33 and 34 are normally closed due to the biasing force of an elastic body such as a spring, but they open when the pressure difference between their upstream and downstream sides exceeds a predetermined pressure difference.

[0032] In other words, the differential pressure drive valve 33 is opened when, for example, a malfunction such as blockage occurs in the control valve 18A and the pressure in the branch piping section 14A falls below a predetermined pressure value compared to the pressure in the branch piping section 14B, allowing the gaseous refrigerant in the branch piping section 14B to flow into the branch piping section 14A via the connecting pipe 31 and the differential pressure drive valve 33. Similarly, the differential pressure drive valve 34 is opened when, for example, a malfunction such as blockage occurs in the control valve 18B and the pressure in the branch piping section 14B falls below a predetermined pressure difference compared to the pressure in the branch piping section 14A, allowing the gaseous refrigerant in the branch piping section 14A to flow into the branch piping section 14B via the connecting pipe 32 and the differential pressure drive valve 34.

[0033] As described above, in the third embodiment, when the pressure difference in the branch pipe sections 14A and 14B of the cooling pipe 13 that supplies gaseous refrigerant to the high-temperature superconducting coils 11A and 11B exceeds a predetermined pressure difference, the differential pressure drive valve 33 of the connecting pipe 31 or the differential pressure drive valve 34 of the connecting pipe 32 that connects the branch pipe sections 14A and 14B is opened. Therefore, even if a malfunction such as blockage occurs in the control valve 18A of the branch pipe section 14A or the control valve 18B of the branch pipe section 14B, the gaseous refrigerant flows from the branch pipe section 14B to the branch pipe section 14A via the connecting pipe 31 and the differential pressure drive valve 33, and from the branch pipe section 14A to the branch pipe section 14B via the connecting pipe 32 and the differential pressure drive valve 34. As a result, similar to the effect (1) of the first embodiment, the high-temperature superconducting coils 11A and 11B can be continuously cooled.

[0034] [D] Fourth embodiment (Figure 4) Figure 4 is a piping diagram showing a part of the cryogenic cooling system according to the fourth embodiment. In this fourth embodiment, parts that are the same as in the first embodiment are denoted by the same reference numerals as in the first embodiment, and their explanation is simplified or omitted. Note that Figure 4 shows the configuration below the cryogenic refrigerator in the cryogenic cooling system shown in Figure 1.

[0035] The difference between the cryogenic cooling system 40 of this fourth embodiment and the first embodiment is that there are no connecting pipes and connecting valves, and in the multiple branch pipe sections of the cooling pipe 13 (for example, branch pipe sections 14A and 14B), for example, a bypass pipe 41 that bypasses the control valve 18A is provided in branch pipe section 14A, and a bypass pipe 42 that bypasses the control valve 18B is provided in branch pipe section 14B, and differential pressure driven valves 43 and 44 that function as bypass valves are provided in each of the bypass pipes 41 and 42, respectively.

[0036] The differential pressure driven valves 43 and 44 are normally closed by the biasing force of an elastic body such as a spring, but they open when the pressure difference between their upstream and downstream sides exceeds a predetermined pressure difference.

[0037] In other words, the differential pressure driven valve 43 is opened when, for example, a malfunction such as blockage occurs in the control valve 18A and the pressure downstream of the control valve 18A in the branch piping section 14A becomes lower than the pressure upstream by a predetermined pressure difference, allowing the gaseous refrigerant upstream of the control valve 18A in the branch piping section 14A to flow downstream of the control valve 18A via the bypass pipe 41. Similarly, the differential pressure driven valve 44 is opened when, for example, a malfunction such as blockage occurs in the control valve 18B and the pressure downstream of the control valve 18B in the branch piping section 14B becomes lower than the pressure upstream by a predetermined pressure difference, allowing the gaseous refrigerant upstream of the control valve 18B in the branch piping section 14B to flow downstream of the control valve 18B via the bypass pipe 42.

[0038] As described above, in the fourth embodiment, when the pressure difference between the upstream and downstream sides of the control valves 18A and 18B, each provided in the branch piping sections 14A and 14B of the cooling pipe 13 that supplies gaseous refrigerant to the high-temperature superconducting coils 11A and 11B, exceeds a predetermined pressure difference, the differential pressure drive valves 43 and 44, each provided in the bypass pipes 41 and 42, open. Therefore, if a malfunction such as blockage occurs in the control valve 18A or 18B, the differential pressure drive valve 43 or 44 opens, and gaseous refrigerant is supplied to the high-temperature superconducting coils 11A or 11B via the bypass pipes 41 or 42. As a result, similar to the effect (1) of the first embodiment, even if a malfunction occurs in the control valves 18A or 18B, the high-temperature superconducting coils 11A and 11B can be continuously cooled.

[0039] [E] Fifth embodiment (Figure 5) Figure 5 is a piping diagram showing a part of the cryogenic cooling system according to the fifth embodiment. In this fifth embodiment, parts that are the same as in the first embodiment are denoted by the same reference numerals as in the first embodiment, and their explanation is simplified or omitted. Note that Figure 5 shows the configuration below the cryogenic refrigerator in the cryogenic cooling system shown in Figure 1.

[0040] The difference between the cryogenic cooling system 50 of this fifth embodiment and the first embodiment is that there are no connecting pipes and connecting valves, multiple high-temperature superconducting coils (e.g., high-temperature superconducting coils 11A, 11B) 11 are thermally connected by a heat transfer member 51, the temperatures of the high-temperature superconducting coils 11A, 11B are measured by temperature measuring means 21A, 21B, and a control unit 52 is provided to control the opening degree of control valves 18A, 18B.

[0041] In other words, the control unit 52 first determines the occurrence of a malfunction, such as blockage, in the control valve 18A or 18B, causing the high-temperature superconducting coil 11A or 11B to overheat, based on the temperature measurement value of the temperature measuring means 21A or 21B. Next, the control unit 52 increases the opening of the functioning control valve 18B or 18A, which is not malfunctioning, thereby supplying more gaseous refrigerant to the high-temperature superconducting coil 11B or 11A, and cooling the high-temperature superconducting coil 11A or 11B connected to the malfunctioning control valve 18A or 18B by heat conduction through the heat transfer member 51.

[0042] As described above, since the high-temperature superconducting coils 11A and 11B are thermally connected by the heat transfer member 51, even if a malfunction occurs in the control valves 18A and 18B, the high-temperature superconducting coils 11A and 11B can be continuously cooled by the heat conduction of the heat transfer member 51, similar to the effect (1) of the first embodiment.

[0043] [F] Sixth embodiment (Figure 6) Figure 6 is a piping diagram showing a part of the cryogenic cooling system according to the sixth embodiment. In this sixth embodiment, parts that are the same as those in the first and second embodiments are denoted by the same reference numerals as in the first and second embodiments, and their descriptions are simplified or omitted. Note that Figure 6 shows the configuration below the cryogenic refrigerator in the cryogenic cooling system shown in Figure 1.

[0044] The difference between the cryogenic cooling system 60 of this sixth embodiment and the first and second embodiments is that there are no connecting pipes and connecting valves, and multiple branch piping sections (for example, branch piping sections 14A-1 and 14A-2) are connected to each of the multiple high-temperature superconducting coils (for example, high-temperature superconducting coils 11A and 11B), that is, multiple branch piping sections (for example, branch piping sections 14B-1 and 14B-2) are connected to each of the multiple high-temperature superconducting coils (for example, high-temperature superconducting coils 11A and 11B).

[0045] Furthermore, in the cryogenic cooling system 60, flow rate measuring means 26A-1, 26A-2, 26B-1, and 26B-2 are provided in each of the branch piping sections 14A-1, 14A-2, 14B-1, and 14B-2, respectively. In addition, the cryogenic cooling system 60 is provided with a control unit 62 that controls the opening degree of each of the control valves 18A-1, 18A-2, 18B-1, and 18B-2 provided in the branch piping sections 14A-1, 14A-2, 14B-1, and 14B-2, respectively.

[0046] In other words, the control unit 62 first determines, based on the flow rate measurements of the flow rate measuring means 26A-1, 26A-2, 26B-1, and 26B-2, that a malfunction such as blockage has occurred in the control valves 18A-1, 18A-2, 18B-1, and 18B-2. If a malfunction occurs in control valves 18A-1 and 18B-1, the control unit 62 then increases the opening of the healthy control valves 18A-2 and 18B-2, which are not malfunctioning, thereby increasing the refrigerant flow rate through the branch piping sections 14A-2 and 14B-2, respectively, and thereby ensuring the continued cooling of the high-temperature superconducting coils 11A and 11B.

[0047] As described above, a single high-temperature superconducting coil 11A is connected to multiple branch piping sections, branch piping sections 14A-1 and 14A-2, and a single high-temperature superconducting coil 11B is connected to multiple branch piping sections, branch piping sections 14B-1 and 14B-2. Therefore, even if a malfunction occurs in one of the control valves 18A-1 and 18A-2 provided in branch piping sections 14A-1 and 14A-2, gaseous refrigerant can be supplied to the high-temperature superconducting coil 11A from branch piping section 14A-2 or 14A-1, which is equipped with a functioning control valve 18A-2 or 18A-1 that is not malfunctioning. As a result, similar to the effect (1) of the first embodiment, the high-temperature superconducting coils 11A and 11B can be continuously cooled.

[0048] Although several embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be carried out in various other forms, and various omissions, substitutions, modifications, and combinations can be made without departing from the spirit of the invention, and such substitutions, modifications, and combinations are included in the scope and spirit of the invention, as well as in the claims and their equivalents. [Explanation of Symbols]

[0049] 10...Cryogenic cooling system, 11A, 11B...High-temperature superconducting coil, 12...Cryogenic refrigerator, 13...Cooling piping, 14A, 14A-1, 14A-2, 14B, 14B-1, 14B-2...Branch piping section, 18A, 18B...Control valve, 19...Connecting piping, 20...Connecting valve, 21A, 21B...Temperature measuring means, 22...Control unit, 25...Cryogenic cooling system, 26A, 26B...Flow rate measuring means, 27...Control unit, 30...Cryogenic cooling system, 31, 32...Connecting piping, 33, 34...Differential pressure driven valve, 40...Cryogenic cooling system, 41, 42...Bypass piping, 43, 44...Differential pressure driven valve, 50...Cryogenic cooling system, 51...Heat transfer member, 52...Control unit, 60...Cryogenic cooling system, 62...Control unit

Claims

1. A cryogenic refrigerator and multiple objects to be cooled are connected by a cooling pipe that has branched sections corresponding to the objects to be cooled, and a control valve is provided in each of the branched sections. In a cryogenic cooling system in which the flow rate of refrigerant flowing from the cryogenic refrigerator to the object to be cooled is controlled by the control valve, A cryogenic cooling system characterized in that multiple objects to be cooled are thermally connected by heat transfer members.

2. Each of the objects to be cooled is provided with a temperature measuring means for measuring the temperature of the object to be cooled, and the control unit further comprises a temperature measuring means for inputting the temperature measurement value from the temperature measuring means. The cryogenic cooling system according to claim 1, characterized in that the control unit is configured to determine, when the rate of change of the temperature measurement value exceeds a predetermined value, that a malfunction has occurred in the control valve that supplies refrigerant to the object to be cooled, on which the temperature measuring means that measured the temperature is installed, and to increase the opening degree of the control valve that is not malfunctioning.

3. A cryogenic refrigerator and multiple objects to be cooled are connected by a cooling pipe that has branched sections corresponding to the objects to be cooled, and a control valve is provided in each of the branched sections. In a cryogenic cooling system in which the flow rate of refrigerant flowing from the cryogenic refrigerator to the object to be cooled is controlled by the control valve, The cryogenic cooling system is characterized in that the branched piping section is configured by connecting multiple piping sections to a single object to be cooled.

4. Each of the aforementioned branch pipe sections is provided with a flow rate measuring means for measuring the flow rate of the refrigerant flowing inside the branch pipe section, and the system further comprises a control unit that receives the flow rate measurement value from the flow rate measuring means. The cryogenic cooling system according to claim 3, characterized in that the control unit is configured to determine, when the flow rate measurement value falls below a predetermined flow rate, that a malfunction has occurred in the control valve disposed in the branch piping section where the flow rate measuring means that measured the flow rate measurement value is provided, and to increase the opening degree of the control valve that is not malfunctioning.

5. In a cryogenic cooling method in which a refrigerant is flowed from a cryogenic refrigerator to multiple objects to be cooled via multiple branch pipe sections of a cooling pipe, and the flow rate of the refrigerant is controlled by control valves installed in each of the branch pipe sections, A cryogenic cooling method characterized in that a plurality of objects to be cooled are thermally connected by a heat transfer member, and the objects to be cooled are cooled by heat conduction by the heat transfer member.

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