JP2001012836A - Cryogenic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently remove oxygen or water remaining in a closed loop by a simple configuration after extracting a refrigerant from all cooling circuits in maintenance. SOLUTION: When evaporation bubbles 11 are generated in a closed loop that is composed of an upper auxiliary liquid storage part 7, cooling piping 8a, a bottom auxiliary liquid storage part 9, and cooling piping 8b, maintenance operation is done for extracting a refrigerant from all cooling circuits. In this case, although oxygen or water remains in the closed loop, the oxygen or water can be efficiently removed by energizing a heater 15 mounted to the bottom auxiliary liquid storage part 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cryogenic apparatus for cooling an object to be cooled to a cryogenic state using a liquefied refrigerant such as liquefied nitrogen.

[0002]

2. Description of the Related Art In order to use a superconducting magnet device in a superconducting state, it is necessary to cool a superconducting coil to a cryogenic state. In the field of linear motor cars, in general, liquefied nitrogen,
A system that naturally circulates a refrigerant such as liquefied helium is often used. FIG. 10 is a configuration diagram of a conventional cryogenic device employing such a natural circulation system.

[0003] In FIG. 10, a refrigerant reservoir 2 is provided above a vacuum insulated container 1.
Is connected to a liquefied refrigerant supply pipe 3 and a vaporized refrigerant exhaust pipe 4. A liquefied refrigerant (for example, liquefied nitrogen) from a liquefier (not shown) is supplied from the liquefied refrigerant supply pipe 3 into the refrigerant liquid reservoir 2. The vaporized refrigerant vaporized above the liquid surface 5a of the refrigerant liquid 5 stored therein is discharged from the vaporized refrigerant exhaust pipe 4 and returns to the liquefier.

A connection pipe 6 is attached to the bottom of the coolant reservoir 2, and the coolant reservoir 2 is connected through the connection pipe 6.
An upper auxiliary liquid reservoir 7 communicating with the inside is provided below the refrigerant liquid reservoir 2. Two bellows-like cooling pipes 8a, 8b extend downward from the upper auxiliary liquid reservoir 7, and these two cooling pipes 8a, 8b join at the bottom auxiliary liquid reservoir 9. Therefore, these upper auxiliary liquid reservoir 7, cooling pipe 8
a, a bottom auxiliary liquid reservoir 9, and a cooling pipe 8b form a closed loop cooling circuit. A cooling target 10 (for example, the above-described superconducting magnet device) is provided around the cooling pipes 8a and 8b, and the cooling target 10 and the cooling pipes 8a and 8 are provided.
By performing heat exchange with the refrigerant liquid 5 passing through the inside b, the object to be cooled 10 is cooled down to an extremely low temperature state. The heat exchange at this time generates vapor bubbles 11 in the closed loop.
The inclination angle and diameter of the cooling pipes 8a and 8b are determined by the fact that the buoyancy of the vaporized bubbles 11 overcomes the surface tension and the adhesive strength.
It is designed so as not to adhere to the tube walls of a and 8b as much as possible. In addition, as a main material used for the cooling pipes 8a and 8b, a good heat conductor such as aluminum, copper, or an alloy thereof, or a stainless steel capable of maintaining high strength even in a very low temperature state is used. Is done.

A room temperature gas distribution pipe 12 is connected to a lower portion of the bottom auxiliary liquid reservoir 9.
A bellows joint 13 and a valve 14 are attached in the middle of the process. A supply source of a non-illustrated room-temperature gas (a gas of the same type as the refrigerant liquid 5, which is assumed to be a nitrogen gas in the conventional apparatus) is provided to the external port 12a at the upper end of the room-temperature gas distribution pipe 12. It is connected. Valve 14
Is always in a closed state, so that the liquid level 5a of the refrigerant liquid 5 in the normal temperature gas distribution pipe 12 is the same as the liquid level 5a of the refrigerant liquid 5 in the refrigerant liquid reservoir 2 as shown in the figure. Height. In FIG. 10, in order to simplify the drawing as much as possible, the detailed structure of
A radiation shield plate that covers the periphery of the cooled object 10 and the coolant reservoir 2, or various valves and sensors are not shown.

Next, the operation of FIG. 10 will be described. The refrigerant liquid 5 supplied from the liquefied refrigerant supply pipe 3 is supplied to the refrigerant liquid reservoir 2.
And a part of the heat is exchanged with the cooled object 10 around a closed loop formed by the upper auxiliary liquid reservoir 7, the cooling pipe 8a, the bottom auxiliary liquid reservoir 9, and the cooling pipe 8b. . Evaporation bubbles 11 are generated in the process of heat exchange at this time. As described above, the inclination angles of the cooling pipes 8a and 8b and the inclination angles of the cooling pipes 8a and 8b are set so that the buoyancy of the evaporation bubbles 11 can overcome its surface tension and adhesive force. Because the diameter etc. are designed,
Most of the evaporating bubbles 11 float toward the upper coolant reservoir 2. A part of the refrigerant liquid 5 which has completed the heat exchange with the cooled object 10 in the closed loop is vaporized, discharged from the vaporized refrigerant exhaust pipe 4 to the outside of the vacuum insulated container 1, and collected in a liquefier (not shown). You.

As described above, the refrigerant liquid 5 and the cooled object 1
0, and the supply of the liquefied refrigerant from the liquefied refrigerant supply pipe 3 to the refrigerant liquid reservoir 2 is repeatedly performed. However, after a certain period of time, the air in the refrigerant liquid 5 The amount of oxygen and moisture increases, and the amount of evaporative bubbles 11 present in the closed loop also increases. When the amount of the evaporating bubbles 11 increases, the smooth flow of the refrigerant liquid 5 in the closed loop is hindered. Not only lowers the heat exchange efficiency, but also causes cracks in the cooling pipes 8a and 8b (particularly the aluminum pipe portion) due to oxygen and moisture contained in the evaporating bubbles 11, making the operation of the apparatus impossible. That could happen.

Therefore, when the amount of the evaporative bubbles 11 exceeds a certain amount (the amount of the evaporative bubbles 11 is estimated based on monitoring of a temperature change, a temperature rise rate, and the like in each part of the object 10 to be cooled). Is stopped, and maintenance work for replacing the refrigerant in all the cooling circuits is performed. However, if oxygen or moisture remains in the cooling circuit, many vapor bubbles 11 will be generated again after the operation of the apparatus is restarted. Therefore, at the time of performing the maintenance work, the refrigerant is extracted from all the cooling circuits, then the valve 14 is opened, and the room temperature nitrogen gas is supplied from the room temperature gas supply source (not shown) into the room temperature gas distribution pipe 12. Introduce it. As a result, oxygen or moisture remaining in the closed loop and the cooling circuit above the closed loop can be removed.

[0009]

As described above, FIG.
Is provided with a normal temperature gas distribution pipe 12, and blows the normal temperature gas into a closed loop formed by the upper auxiliary liquid reservoir 7, the cooling pipe 8a, the bottom auxiliary liquid reservoir 9, and the cooling pipe 8b, thereby forming a closed loop cooling circuit. Further, it is intended to remove oxygen or moisture remaining in the cooling circuit above it. However, since such a cooling circuit configuration has a large structural restriction, it has been extremely disadvantageous in terms of design, particularly in a field such as a linear motor car in which the size and weight of the device are strongly required. .

For example, since the refrigerant liquid 5 always exists in the normal temperature gas distribution pipe 12, the external port 12a
Must be higher than the coolant reservoir 2, and a valve 14 as a shut-off valve must be provided to keep the inside of the normal-temperature gas flow pipe 12 in a vacuum state. Further, since the temperature of the ordinary temperature gas distribution pipe 12 changes over a wide range from a normal temperature state to an extremely low temperature state, it is necessary to provide a bellows joint 13 for absorbing a difference in heat shrinkage of various members in the middle of the pipe.

As described above, the configuration of the cooling circuit as shown in FIG. 10 has to adopt a complicated piping configuration.
Moreover, the normal temperature gas distribution pipe 12 has an additional characteristic that is not used at all during operation of the apparatus. Therefore, a configuration in which the room temperature gas distribution pipe 12 is omitted drastically has been conventionally considered. However, in the case where the normal temperature gas distribution pipe 12 is omitted, once a situation in which the closed loop is closed by the evaporation bubble 11 occurs, the operation of the apparatus is stopped immediately, and then the entire cooling circuit is started. It is necessary to perform a complicated operation such as removing the refrigerant liquid 5 to completely raise the temperature of the apparatus and repeating the operation of replacing the cooling circuit with high-purity gas many times. Therefore, a large amount of recovery time is required, which is a serious problem in operation.

As a measure for removing oxygen or moisture remaining in the closed loop after the refrigerant is drawn, it has been considered to attach a heating heater to the entire cooling pipes 8a and 8b. The total capacity of the heater for heating becomes very large, which results in an impractical configuration.

The present invention has been made in view of the above circumstances, and after removing refrigerant from all cooling circuits at the time of maintenance, efficiently removes oxygen or moisture remaining in a closed loop while having a simple configuration. It is intended to provide a cryogenic device that can be obtained.

[0014]

Means for Solving the Problems As means for solving the above-mentioned problems, the invention according to claim 1 comprises a refrigerant reservoir having a liquefied refrigerant supply pipe and a vaporized refrigerant exhaust pipe; Through both auxiliary liquid reservoirs of an upper auxiliary liquid reservoir disposed below and communicating with the inside of the refrigerant liquid reservoir, and a bottom auxiliary liquid reservoir disposed further below the upper auxiliary liquid reservoir. Forming a closed-loop cooling circuit, a cooling pipe disposed so that the liquefied refrigerant circulating in the closed loop can exchange heat with the object to be cooled, and a cryogenic device of a natural circulation cooling system including: A heating heater for removing oxygen or moisture remaining in the closed loop after removing the refrigerant from all the cooling circuits during maintenance is attached to the bottom auxiliary liquid reservoir.

According to a second aspect of the present invention, in the first aspect of the present invention, a plurality of the closed loops are formed.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the heating heater is also attached to the upper auxiliary liquid reservoir.

According to a fourth aspect of the present invention, in the first aspect of the present invention, a thermometer is mounted on a mounting portion of the heating heater.

According to a fifth aspect of the present invention, in the first aspect of the present invention, the heating heater is mounted via a good heat conducting member.

According to a sixth aspect of the present invention, in the first aspect of the present invention, the heating heater comprises:
It is characterized in that a magnetic field variation in one resistor portion forms an inductive circuit that is offset by a magnetic field variation in another resistor portion arranged along the resistor portion.

According to a seventh aspect of the present invention, in the sixth aspect of the present invention, the resistor portion of the heating heater is formed such that a folded portion is formed at one position. .

According to an eighth aspect of the present invention, in the sixth aspect of the present invention, the resistor portion of the heating heater is formed such that a plurality of folded portions are formed.
It is characterized by the following.

According to a ninth aspect of the present invention, in the heater according to the sixth aspect, a common connection portion for connecting the certain resistor portion and the other resistor portion is provided so that a folded portion is not formed. Characterized in that:

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. However, the same components as those in FIG. 10 are denoted by the same reference numerals, and redundant description will be omitted. FIG. 1 is a configuration diagram of the first embodiment. FIG. 1 differs from FIG.
The point is that the room temperature gas distribution pipe 12, the bellows joint 13, the valve 14, and the like are deleted, and the point that the heater 15 is attached to the bottom auxiliary liquid reservoir 9. The heater 15 is intended to promote the vaporization of oxygen or moisture remaining in a closed loop formed by the upper auxiliary liquid reservoir 7, the cooling pipe 8a, the bottom auxiliary liquid reservoir 9, and the cooling pipe 8b. . In the heating heater 15, the resistor portion is covered with an insulating resin and formed in a flat shape, so that the heat conduction efficiency is increased and the heater 15 can be easily attached. . In addition, heater 1 for heating
5 is attached to and integrated with the bottom surface of the bottom auxiliary liquid reservoir 9 with an adhesive. The adhesive is mainly composed of an epoxy resin containing a reinforcing agent having good heat conductivity, Alternatively, it is preferable to use a thermoplastic resin or the like mainly containing a copolymer of ethylene and methacrylic acid.

Next, the operation of FIG. 1 will be described. As described above, the generation amount of the evaporative bubbles 11 is estimated based on monitoring of a temperature change, a temperature rise rate, and the like in each part of the object to be cooled 10, and when the generation amount of the evaporative bubbles 11 exceeds a certain amount, Stop operation of the device and perform maintenance work.
In other words, the refrigerant is evacuated to extract the refrigerant from all the cooling circuits. And then, the heater 1 for heating
5 between the heater terminals. This promotes the vaporization of oxygen or moisture remaining in the closed loop and removes them all after a certain time.

As is apparent from a comparison of the configuration of FIG. 1 with FIG. 10, the configuration of FIG. 1 does not include the normal-temperature gas distribution pipe 12 and the like, and instead includes a heater 15 for the bottom auxiliary liquid reservoir 9.
It's a simple one just attached to Therefore, it is extremely advantageous in terms of design in a field such as a linear motor car in which miniaturization and weight reduction are strongly required. Further, the time during which oxygen or moisture remaining in the closed loop can be removed by energizing the heating heater 15 is also shorter than the case where the room temperature gas distribution pipe 12 of FIG. 10 is used, and the maintenance time can be greatly reduced. Can be. Further, the heating heater 15 is energized even when the cooling circuit is still in a very low temperature state while the refrigerant is being extracted from the cooling circuit, that is, while the cooling circuit is being evacuated. If this is the case, the time for removing oxygen or moisture from the closed loop can be further reduced.

FIG. 2 is a configuration diagram of the second embodiment. FIG. 2 differs from FIG. 1 in that there are two cooled bodies, 10A and 10B, and the upper auxiliary liquid reservoirs 7A and 7B, respectively.
This is the point that a communication pipe 16 is provided between B, and the point that a heater 15 is attached to each bottom auxiliary liquid reservoir 9. Since the present invention is simple in that the heater 15 is simply attached to the bottom auxiliary liquid reservoir 9, even if the number of objects to be cooled increases, the size and weight of the entire apparatus hardly change. . The operation of the second embodiment is the same as that of the first embodiment, and the description is omitted.

FIG. 3 is a block diagram of the third embodiment. FIG. 3 differs from FIG. 1 in that a thermometer 17 is attached to an attachment portion of the heater 15 in the bottom auxiliary liquid reservoir 9. Thus, the thermometer 1 is provided in the bottom auxiliary liquid reservoir 9.
By mounting the device 7, it is possible to estimate the generation amount of the evaporative bubbles 11 in the bottom auxiliary liquid reservoir 9 during operation of the apparatus, and to monitor the behavior of a temperature rise change due to energization of the heating heater 15 during maintenance. .

FIG. 4 is a configuration diagram of the fourth embodiment. FIG. 4 differs from FIG. 1 in that a heating heater 18 is attached to the upper auxiliary liquid reservoir 7. The upper auxiliary liquid reservoir 7 is a location where the evaporation bubbles 11 easily stay together with the bottom auxiliary liquid reservoir 9, and therefore is a location where oxygen or moisture easily remains even during maintenance. By attaching the heating heater 18 to the upper auxiliary liquid reservoir 7 as well, it becomes possible to more quickly remove oxygen or moisture remaining in the closed loop.

FIG. 5 is a configuration diagram of the fifth embodiment. In this embodiment, a heater 18 is attached to each of the upper auxiliary liquid reservoirs 7A and 7B in the configuration shown in FIG.

FIG. 6 is a configuration diagram of the sixth embodiment. 6 is different from FIG. 1 in that the upper end side of the connecting member 19 is attached to the bottom surface of the bottom auxiliary liquid reservoir 9 and the good heat conducting plate 20 is attached to the lower end side of the connecting member 19. . The periphery of the good heat conducting plate 20 is supported by the radiation shield plate 21. The material of the good heat conductive plate 20 includes aluminum, aluminum alloy, copper, copper alloy and the like. Further, in FIG. 6, the radiation shield plate 21 is shown without being omitted, but this radiation shield plate 21 is not shown in FIGS.
0 is a member provided also in the configuration of FIG.

According to the sixth embodiment, the heater 15 can be easily mounted. In other words, the size of the bottom auxiliary liquid reservoir 9 is not always the same, and differs depending on the model of the apparatus. Therefore, depending on the model, the heater heating surface is too large than the heating surface of the bottom auxiliary liquid reservoir 9. In some cases, installation may not be successful. In this embodiment,
Since the heater 15 is attached via the good heat conducting plate 20, even if the size of the bottom auxiliary liquid reservoir 9 is different for each model, one heater 15 is used.
It is possible to limit the number of types to those having different sizes, and it is not necessary to increase the types of the heaters 15 for heating.

FIGS. 7 to 9 are explanatory diagrams showing the configuration of the heater 15 used in each of the above embodiments. In FIG. 7, the heater 15 includes heater terminals 22 and 23, a first resistor 24, a second resistor 25 disposed along the first resistor 24, and a first resistor 25.
Of the first resistor 24, the second resistor 25, and the folded portion 26, which are formed between the first resistor 24, the second resistor 25, and the second resistor 25. And an insulating member 27.

As the resistor portion, a thin wire-shaped one, a copper-nickel alloy, a stainless steel material or the like processed into a thin plate to have a certain width is used.
The electric resistance of the energizing circuit of the heater 15 is set to be able to maintain about several hundred Ω even at a low temperature. Further, as the insulating member 27, for example, PVF (polyvinyl formal), PTFE (polytetrafluoroethylene), or the like is used.

The arrow shown in the figure indicates the direction of the current. As shown, the direction of the current flowing through the first resistor 24 and the direction of the current flowing through the second resistor 25 are opposite to each other. Direction, and these resistor portions form a non-inductive circuit. As described above, since the resistor portion of the heater 15 is formed so as to form a non-inductive circuit, even if a magnetic field fluctuates around the heater 15, a current caused by the magnetic field fluctuates. Flow can be prevented.

That is, the energization of the heater 15 is performed at the time of maintenance.
5 itself is attached even during operation of the apparatus, so that if the object to be cooled 10 is accompanied by a magnetic field fluctuation such as a superconducting magnet apparatus, the object to be cooled will be directly affected by the magnetic field fluctuation. Become. Therefore, if the resistor portion of the heater 15 is formed in a normal spiral shape,
Assuming that the current was flowing in the same direction,
Even when power is not supplied from the power supply, an induction current is generated by the electromagnetic induction phenomenon during operation of the device, and heat is generated.
This results in unnecessarily increasing the load on the cooling circuit.

However, according to the configuration shown in FIG. 7, even if a magnetic field fluctuates around the heating heater 15, the magnetic field lines generated by the current flowing through the first resistor 24 and the second resistor Since the lines of magnetic force generated by the current flowing in the resistor 25 cancel each other, no current flows through these resistor portions and no heat is generated.

FIG. 7 shows a folded portion 2 having a small heater capacity.
6 is a case where only one place is formed,
If the heater capacity is large, it can be dealt with by providing a plurality of folded portions 26 as shown in FIG. Also, instead of the configuration of FIG. 7, as shown in FIG. 9, the first resistor 24 and the second resistor 25 are connected by providing a common connection portion 28, and two closed loop circuits are provided. In this way, a non-guided cycle may be formed. According to the configuration of FIG. 9, since the folded portion 26 does not need to be provided, the manufacture of the heating heater 15 is further facilitated.

The heater 15 shown in FIGS. 7 to 9 has a circular planar shape. However, in the present invention, various shapes such as a square and a rectangle correspond to the shape of the heater mounting portion. Can be adopted.

In each of the embodiments described above, it is assumed that the object to be cooled 10 generates a magnetic field fluctuation, for example, a superconducting magnet device of a linear motor car. Is not particularly limited to this, and the technology of the present invention may be applied to a cooled object that does not generate a magnetic field fluctuation.

[0040]

As described above, according to the present invention, a heater for heating is attached to the bottom auxiliary liquid reservoir.
Even with a simple configuration, it is possible to efficiently remove oxygen or moisture remaining in the closed loop after extracting the refrigerant from all cooling circuits during maintenance.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a second embodiment of the present invention.

FIG. 3 is a configuration diagram of a third embodiment of the present invention.

FIG. 4 is a configuration diagram of a fourth embodiment of the present invention.

FIG. 5 is a configuration diagram of a fifth embodiment of the present invention.

FIG. 6 is a configuration diagram of a sixth embodiment of the present invention.

FIG. 7 is an explanatory diagram showing a configuration of a heater 15 used in each of the above embodiments.

FIG. 8 is an explanatory diagram showing a configuration of a heater 15 used in each of the above embodiments.

FIG. 9 is an explanatory view showing a configuration of a heater 15 used in each of the embodiments.

FIG. 10 is a configuration diagram of a conventional cryogenic device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum heat insulation container 2 Refrigerant liquid storage part 3 Liquefied refrigerant supply pipe 4 Vaporized refrigerant exhaust pipe 5 Refrigerant liquid 5a Liquid surface 6 Connection pipe 7, 7A, 7B Upper auxiliary liquid storage parts 8a, 8b Cooling pipe 9 Bottom auxiliary liquid storage part 10 , 10A, 10B Object to be cooled 11 Evaporation bubble 12 Room temperature gas flow pipe 13 Bellows joint 14 Valve 15 Heater 16 Communication pipe 17 Thermometer 18 Heater 19 Connection member 20 Good heat conduction plate 21 Radiation shield plate 22, 23 Heater Terminal 24 First resistor 25 Second resistor 26 Folded part 27 Insulating member 28 Common connection part

Claims (9)

[Claims] A refrigerant reservoir having a liquefied refrigerant supply pipe and a vaporized refrigerant exhaust pipe; an upper auxiliary liquid reservoir disposed below the refrigerant liquid reservoir and communicating with the interior of the refrigerant liquid reservoir; A closed loop cooling circuit is formed through both auxiliary reservoirs of the bottom auxiliary reservoir disposed further below the upper auxiliary reservoir, and the liquefied refrigerant circulating through the closed loop communicates with the object to be cooled. A cooling pipe arranged so that heat can be exchanged in a cryogenic device of a natural circulation cooling system comprising: oxygen or moisture remaining in the closed loop after removing the refrigerant from all cooling circuits during maintenance. A cryogenic device, wherein a heater for removing the water is attached to the bottom auxiliary liquid reservoir. 2. The cryogenic device according to claim 1, wherein a plurality of said closed loops are formed. 3. The cryogenic device according to claim 1, wherein the heater for heating is also attached to the upper auxiliary reservoir. 4. The cryogenic device according to claim 1, wherein a thermometer is mounted on a mounting portion of the heating heater. 5. The cryogenic device according to claim 1, wherein said heater for heating is mounted via a good heat conducting member. 6. The heating heater forms a non-inductive circuit in which a magnetic field variation in a certain resistor portion is offset by a magnetic field variation in another resistor portion disposed along the resistor portion. The cryogenic device according to any one of claims 1 to 5, wherein: 7. The cryogenic device according to claim 6, wherein the resistor portion of the heating heater is formed so that a folded portion is formed at one position. 8. The cryogenic device according to claim 6, wherein the resistor portion of the heater is formed so that a folded portion is formed at a plurality of positions. 9. The heating heater according to claim 1, wherein a common connection portion for connecting the certain resistor portion and the other resistor portion is provided so that a folded portion is not formed. The cryogenic device according to claim 6, wherein