JP2007127298A - Cryogenic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent inflow of atmospheric air into a refrigerating machine sleeve in replacing the refrigerating machine of a cryogenic device. <P>SOLUTION: The inflow of outside air into a refrigerating machine insertion space can be prevented by forming a purge gas flow directing to a device external side from a storing case 14 side in the space by introducing a purge gas into the refrigerating machine insertion space from the external through a purge gas introduction tube 80 when the refrigerating machine 30 is taken out from the refrigerating machine insertion space connected with the storing case 14 and the external of the device. The purge gas introduction tube 80 is disposed along the refrigerating machine 30, and can be inserted and removed with respect to the refrigerating machine insertion space with the refrigerating machine 30. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cryogenic device for cooling a superconducting magnet or the like.

  2. Description of the Related Art Conventionally, as a cryogenic device for cooling a superconducting magnet (superconducting magnet) or the like, a device equipped with a cryogenic refrigerator is known. An example is shown in FIG.

  The illustrated apparatus is used as an MRI (Magnetic Resonance Diagnosis Apparatus), and includes a solenoid type superconducting magnet 10, and the magnet 10 is arranged so that the central axis of the solenoid type superconducting magnet 10 faces in the horizontal direction. It is a horizontal type that is placed.

  The illustrated apparatus is of a refrigerant type, and includes a storage container 14 that contains a refrigerant 12 made of liquid helium, a heat shield body 16 that surrounds the storage container 14 from the outside, and a vacuum that further surrounds the heat shield body 16 from the outside. And the superconducting magnet 10 is immersed in the refrigerant 12. A vacuum state is maintained in the gap between the storage container 14 and the vacuum container 18, and the heat shield body 16 is disposed in the gap.

  A magnetic field utilization space 20 extending in the horizontal direction is secured at the center of the apparatus, and the containment vessel 14, the heat shield body 16, and the vacuum vessel 18 are respectively donuts so as to surround the magnetic field utilization space 20. It is formed in a shape.

  The storage container 14 and the heat shield body 16 are respectively formed with sleeves 24 and 26 extending upward from the top wall thereof, and the upper end of the sleeve 24 of the storage container 14 is inside the sleeve 26 of the heat shield body 16. The part is inserted from the bottom. And the refrigerator 30 is arrange | positioned in the space inside these sleeves 24 and 26 so that insertion or removal is possible. That is, both the sleeves 24 and 26 constitute a refrigerator insertion portion that forms a refrigerator insertion space into which the refrigerator 30 is inserted and removed.

  The refrigerator 30 is for recondensing the refrigerant gas generated by the evaporation of the refrigerant 12 in the storage container 14, and the consumption and replenishment frequency of the refrigerant 12 are greatly reduced by the recondensation. Is done.

  In the illustrated example, a two-stage GM refrigerator is used as the refrigerator 30. Specifically, the refrigerator 30 has a substantially cylindrical overall shape extending in the up-down direction, has a first cooling stage 31 in the middle part thereof, and has a set temperature lower than that of the first cooling stage 31 in the lower end part. A low second cooling stage 32 is provided. The first cooling stage 31 is connected to the sleeve 26 of the heat shield body 16 so as to be able to conduct heat, and a fin 34 as a recondenser is connected to the second cooling stage 32 so as to be able to conduct heat. The fin 34 is disposed in the sleeve 24 of the storage container 14. The cooling temperature of the surface of the fin 34 is set to a temperature lower than the condensing temperature of the refrigerant 12 (4.2 K in the case of helium), and the fin 34 is brought into contact with the surface of the fin 34 by the refrigerant gas. The refrigerant gas is recondensed on the surface.

  The storage container 14 is provided with a safety device 36 for avoiding the internal pressure of the container 14 from exceeding a certain level. The safety device 36 includes a safety discharge pipe 37 provided so as to communicate with the outside from the storage container 14, and a safety valve 38 including a check valve provided at an outlet at the upper end of the safety discharge pipe 37. When the pressure in the storage container 14 becomes a certain level or more, the helium gas in the container 14 is released to the outside of the apparatus.

  By the way, in such a cryogenic apparatus, it is necessary to perform regular maintenance work on the refrigerator 30. In general, after the refrigerator 30 is removed from the sleeves 24 and 26, a new refrigerator 30 is inserted into the sleeves 24 and 26, and then the refrigerator 30 is started to move to a steady state. Is called.

  During the maintenance work, when the refrigerator 30 is extracted from the sleeves 24 and 26, there is a possibility that outside air corresponding to the volume occupied by the refrigerator 30 may flow from the outside of the apparatus. If there is an inflow of outside air, there arises a disadvantage that components having a relatively high freezing point such as oxygen, hydrogen, and water vapor contained in the outside air freeze in the sleeves 24 and 26 in an instant. When such freezing occurs, the thermal conductivity between the first cooling stage 31 and the heat shield body 16 of the refrigerator 30 to be newly inserted thereafter decreases, and thus the capacity of the refrigerator 30 is sufficiently exhibited. There is a risk that it will not be possible.

Therefore, as a means for solving such inconvenience, a method as described in Patent Document 1 below has been proposed. In this method, a maintenance bag that can be expanded and contracted is installed so as to close the sleeve in which the refrigerator is inserted from the outside, and the maintenance bag is formed in the maintenance bag in a state where a refrigerant gas is put into the maintenance bag. The maintenance operation of the refrigerator in the maintenance bag is performed from the outside of the bag by using the glove that is provided.
JP-A-5-223379 (pages 3-5, FIG. 4)

  In the method described in Patent Document 1, it is necessary to separately attach a maintenance bag every time the maintenance work of the refrigerator is performed. Furthermore, in order to make the inside of the maintenance bag a refrigerant gas atmosphere, an exhaust blower for sucking air from the bag, a gas cylinder for supplying refrigerant gas into the bag, and the like must be prepared. It becomes very troublesome.

  Further, the maintenance work in the maintenance bag must be performed by an operator inserting his / her hand into the bag through a glove, and the work is not easy.

  In view of such circumstances, the present invention easily performs the maintenance work while effectively suppressing air and the like from flowing into the sleeve in which the refrigerator is inserted during the maintenance work of the refrigerator. The purpose is to provide technology that makes this possible.

  As means for solving the above problems, the present inventors introduced purge gas from the outside of the apparatus through the purge gas introduction pipe into the refrigerator insertion space when pulling out the refrigerator from at least the refrigerator insertion space. The inventors have conceived a method for preventing the outside air from flowing into the refrigerator insertion space by forming a purge gas flow from the storage container side toward the outside of the apparatus in the refrigerator insertion space.

  However, in such a method, when a certain amount of high freezing point impurities (for example, water or carbon dioxide) are mistakenly mixed in the purge gas, the impurities may solidify and cause the purge gas introduction pipe to be blocked. In order to release such a closed state, it is necessary to raise the temperature in the purge gas introduction pipe and vaporize the solidified impurities. At this time, if the purge gas introduction pipe is fixedly installed on the apparatus main body side of the cryogenic apparatus, for example, the entire cryogenic apparatus with demagnetization and temperature rise of the superconducting magnet is required to heat the introduction pipe. The operation must be stopped, and a great deal of time and cost must be spent on the subsequent startup of the apparatus.

  In addition, a method of melting (liquefying) the solidified substance in the purge gas introduction pipe by partial heating without stopping the operation of the entire apparatus is conceivable. Even if this method is carried out, the liquefied impurities remain in the purge gas introduction pipe. It flows down into a low temperature containment vessel and solidifies again here, which is not a radical solution.

  The present invention has been made from the background as described above, and a storage container for storing a cooled object, and a refrigerator that generates cold heat that contributes to cooling the cooled object stored in the stored container. A cryogenic device comprising: a refrigerator insertion portion that is connected to the inside of the containment vessel and the outside of the device and surrounds the refrigerator insertion space into which the refrigerator can be inserted from the outside of the device; and from the refrigerator insertion space A purge gas for preventing outside air from flowing into the refrigerator insertion space when the refrigerator is pulled out of the apparatus is introduced into the refrigerator insertion space from the outside of the apparatus, and the storage container side is connected to the outside of the apparatus. And a purge gas introduction pipe for forming a purge gas flow toward the side. The purge gas introduction pipe is provided along the refrigerator and is inserted into and removed from the refrigerator insertion space together with the refrigerator. Those that are configured.

  The present invention also includes a cryogenic device that includes a refrigerator that is provided in a cryogenic apparatus having a storage container for storing a cooled object, and that generates cold heat that contributes to cooling of the cooled object stored in the storage container. A refrigerator unit for an apparatus, wherein the refrigerator is connected to a refrigerator insertion space formed in the cryogenic apparatus so as to be connected to the outside of the cryogenic apparatus and the inside of the containment vessel. It has an external shape that can be inserted from the outside, and purge gas for preventing outside air from flowing into the refrigerator insertion space when the refrigerator is pulled out from the refrigerator insertion space to the outside of the apparatus. A purge gas introduction pipe for introducing a purge gas flow into the refrigerator insertion space to form a purge gas flow from the storage container side toward the outside of the apparatus is provided, and the purge gas introduction pipe is provided along the refrigerator. Those that are configured to be inserted and removed with respect to the refrigerator insertion space together with the refrigerator.

  According to the above configuration, in a state where the refrigerator is inserted in the refrigerator insertion space, by introducing the purge gas into the refrigerator insertion space through the purge gas introduction pipe provided along the refrigerator, A purge gas flow from the storage container side toward the outside of the apparatus can be formed in the refrigerator insertion space, and by removing the refrigerator from the refrigerator insertion space while forming such a purge gas flow, Sometimes, air or the like can be effectively prevented from flowing into the refrigerator insertion space from the outside of the apparatus.

  Here, even if the impurities in the purge gas solidify and the purge gas introduction pipe is closed, the purge gas introduction pipe is removed from the refrigerator insertion space together with the refrigerator to operate the cryogenic apparatus main body. The purge gas introduction pipe can be restored (heating, etc.) outside the apparatus main body without significantly affecting the apparatus.

  The cryogenic apparatus according to the present invention is a so-called refrigerant type, that is, the containment vessel stores a liquid refrigerant for cooling the object to be cooled, and the object to be cooled is immersed in the refrigerant. The cooling object may be stored in a state, and the refrigerator may recondense the refrigerant gas generated by evaporation of the refrigerant in the storage container in the refrigerator insertion space. The so-called refrigerant-free type, that is, the refrigerator may be connected to the object to be cooled in the storage space so as to be able to conduct heat.

  In the former refrigerant type, the gas discharge port of the purge gas introduction pipe is in the refrigerating machine insertion space at the end in the insertion direction of the refrigerating machine (for example, recondensing fins or the like for recondensing refrigerant gas) It is more preferable that it is arranged so as to face the outside of the apparatus at a position farther away than the part. According to this configuration, even if the refrigerator insertion space is open to the storage container side, a stable purge gas flow from the storage container side toward the outside of the apparatus is formed, and the purge gas is directed to the storage container side. It is possible to suppress the inflow.

  In the present invention, the purge gas introduction pipe only needs to be provided along the refrigerator, and the specific piping mode is not limited. For example, if the purge gas introduction pipe is wound around the refrigerator, the introduction pipe is not easily separated from the refrigerator, and the refrigerator and the purge gas introduction pipe are more smoothly connected to the refrigerator insertion space. Can be inserted and removed.

  In the present invention, in the state where the refrigerator is inserted into the refrigerator insertion space, the outside end portion of the refrigerator insertion space is closed leaving a purge gas discharge passage, and the purge gas is inserted into the purge gas discharge passage. More preferably, a check valve that allows only the flow in the discharge direction to the outside of the apparatus is provided.

  According to this configuration, even in a state before the refrigerator is pulled out from the refrigerator insertion space, by introducing the purge gas introduction pipe from the purge gas introduction pipe into the space and discharging the check valve to the outside of the space, A good purge gas flow can be formed in the refrigerator insertion space. In this way, by forming a stable purge gas flow from the stage prior to the drawing operation of the refrigerator, it is possible to more effectively prevent the atmosphere and the like from flowing into the refrigerator insertion space. Become.

  On the other hand, when the operation of the refrigerator is in a steady state and the temperature of the recondensing chamber is extremely low (near 4K), the inside of the purge gas introduction pipe is moved from the room temperature to the refrigerator insertion space side from the room temperature. The purge gas having a temperature distribution that reaches an extremely low temperature is filled. In such a purge gas introduction pipe filled with a purge gas having a large temperature gradient, there is a possibility that thermoacoustic vibration that often causes a large pulsation or vibration may occur. However, the purge gas introduction pipe passes through a bypass pipe having a valve. When the purge gas introduction pipe is not used, the purge gas introduction pipe is connected to the large volume refrigerator insertion space through the bypass pipe when the purge gas introduction pipe is not used. It is possible to suppress the occurrence of thermoacoustic vibration in the introduction pipe.

  Moreover, in this invention, it is more preferable to provide the gas inflow suppression means which suppresses the purge gas introduce | transduced in the said refrigerator insertion space flowing into the said storage container. According to this configuration, it is possible to suppress the evaporation of the refrigerant in the container due to the purge gas having a temperature higher than that of the refrigerant gas flowing into the storage container, and to effectively reduce the loss of the refrigerant.

  As this gas inflow suppression means, for example, it has a communication part that forms a communication path that connects the refrigerator insertion space and the space in the containment vessel, and the cross-sectional area of the communication path of this communication part is A thing smaller than the minimum flow path cross-sectional area in the said refrigerator insertion space in the state which inserted the said refrigerator in the said refrigerator insertion space is suitable.

  According to this configuration, since the cross-sectional area of the internal space of the connection pipe that connects the refrigerator insertion portion and the storage container is suppressed, the purge gas introduced into the refrigerator insertion space from the purge gas introduction pipe is connected to the connection pipe. Inflow to the tube side, that is, the containment vessel side, is effectively suppressed.

  Further, as the gas inflow suppression means, it is effective to include a valve body that opens and closes a storage container side end of the refrigerator insertion space and a valve operation means for operating the valve body from the outside of the apparatus. is there.

  According to this configuration, when introducing the purge gas, it is possible to effectively prevent the purge gas from flowing into the storage container side by closing the storage container side end of the refrigerator insertion space by the valve body. it can.

  As the valve operating means, an urging means for urging the valve body in a direction in which the valve body opens the storage container side end of the refrigerator insertion space, one end is connected to the valve body, The other end portion is provided with an operation cord that is led out to the outside of the device, and the valve body is inserted against the urging force of the urging means by pulling the operation cord from the outside of the device. It is preferable that the operation cable body is routed so as to move to a position where the storage container side end of the space is closed.

  According to this configuration, during normal use, the urging means holds the valve body in the valve open position, thereby allowing the refrigerant gas to flow from the storage container into the refrigerator insertion space, while introducing the purge gas. The valve body can be closed against the urging force of the urging means simply by operating the operating cord from outside the apparatus.

  Here, the operation cable body has the insertion position of the refrigerator in the refrigerator insertion space so that a pulling operation from the outside of the apparatus is possible even when the refrigerator is present in the refrigerator insertion space. It is more preferable that the cables are routed so as to be bypassed.

  In addition, the valve body is configured in a portion of the valve body that contacts the storage container side end of the refrigerator insertion space in a portion that contacts the valve seat portion of the other party when the valve body is closed. It is more preferable that a seal layer made of a metal material (for example, solder or indium) that is more easily elastically deformed than the material is provided. With this configuration, the sealing performance between the valve body and the valve seat portion can be improved, and the effect of suppressing the inflow of purge gas into the storage container can be enhanced.

  As described above, according to the present invention, the purger is extracted from the space while introducing the purge gas into the refrigerator insertion space through the purge gas introduction pipe provided along the refrigerator. The maintenance work of the refrigerator can be easily performed while preventing air from flowing into the refrigerator. Even if the purge gas introduction pipe is clogged due to solidification of impurities, the purge gas introduction pipe is removed from the refrigerator insertion space together with the refrigerator, so that the operation of the cryogenic apparatus main body is hardly affected. In addition, the purge gas introduction pipe can be restored.

  A first embodiment of the present invention is shown in FIG. Note that the configuration of the cryogenic apparatus according to this embodiment is the same as that shown in FIG. 5 except for the insertion portion of the refrigerator 30 which is the main part, and therefore the common parts will not be described. Hereinafter, only the main part of the apparatus will be described.

  Moreover, although this embodiment applies this invention about the superconducting magnet apparatus which cools the superconducting magnet 10 as a to-be-cooled body, in this invention, regardless of cooling object, a SQUID magnetometer and other superconducting elements are used. It can also be applied to cooling.

  FIG. 1 shows a specific structure of the refrigerator 30 provided in the cryogenic apparatus and the sleeves 24 and 26 constituting the insertion portion of the refrigerator 30.

  As described above, the refrigerator 30 is constituted by a two-stage GM refrigerator, has a substantially cylindrical overall shape extending in the vertical direction, has a first cooling stage 31 in its middle portion, and has a lower end. The part has a second cooling stage 32 having a set temperature lower than that of the first cooling stage 31. Each of the stages 31 and 32 has a flange shape having a larger outer diameter than the other parts, and fins 34 as recondensers are connected to the second cooling stage 32 so as to conduct heat. The outer diameter of the first cooling stage 31 is set larger than the outer diameter of the second cooling stage 32 and the outer diameter of the fins 34.

  On the other hand, the heat shield body 16 and the vacuum vessel 18 are provided with through holes 40 and 42 for inserting the refrigerator 30, respectively, and a refrigerator that surrounds the refrigerator insertion space into which the refrigerator is inserted. A machine insert is provided. Specifically, the refrigerator insertion portion includes sleeves 44 and 46 made of bellows that can be expanded and contracted in the vertical direction, and a sleeve 48 made of a tube material therebelow.

  The sleeve 44 is provided at a position covering the through hole 40 on the outer side (upper side) of the vacuum vessel 18. The lower end of the sleeve 44 is connected in close contact with the top wall of the vacuum vessel 18, and a refrigerator supporting flange 50 fixed to the refrigerator 30 is press-fitted into the upper end opening part so as to be detachable. It has become.

  The refrigerator supporting flange 50 has a flange portion 52 fixed to the refrigerator 30 and a cylindrical press-fit portion 54 extending downward from the flange portion 52. The flange portion 52 is fixed to a portion above the first cooling stage 31 in the refrigerator 30 and has a shape that protrudes greatly from the refrigerator 30 in the radial direction. The press-fit portion 54 has an outer diameter slightly smaller than the inner diameter of the upper end portion of the sleeve 44, and a sealing O-ring 56 is provided over the entire circumference on the outer peripheral surface thereof. The O-ring 56 is press-fitted into the upper end portion so as to be insertable / removable when the O-ring 56 is in close contact with the inner peripheral surface of the upper end portion of the sleeve 44 (airtight state).

  The flange portion 52 of the refrigerator support flange 50 is supported on the top wall of the vacuum vessel 18 via the height adjusting mechanism 60. The height adjusting mechanism 60 is a height having a plurality of screw rods 62 erected around the through hole 42 on the top wall of the vacuum vessel 18 and through holes into which the screw rods 62 can be inserted. An adjustment flange 64 and nuts 66 and 68 screwed to the screw rods 62 are provided, and through holes through which the screw rods 62 can be inserted are provided in the flange portions 52 of the refrigerator support flange 50. It has been. Then, the height adjusting flange 64 is mounted on the lower nut 66, the flange portion 52 is mounted on the height adjusting flange 64, and the nut 68 is tightened from above, thereby the flange portion 52 is connected to the screw rod. It is fixed to 62 so that the height can be adjusted.

  The sleeve 46 is disposed so as to connect the top wall of the vacuum vessel 18 and a first cooling flange 70 disposed below the top wall. Specifically, the upper end of the sleeve 46 is connected in close contact with the peripheral portion of the through hole 42 in the top wall of the vacuum vessel 18, and the lower end of the sleeve 46 is in close contact with the outer peripheral portion of the first cooling flange 70. Linked in state. The outer periphery of the first cooling flange 70 is connected to the top wall of the heat shield body 16 through a heat conductor 72 made of a copper braided wire or the like so as to conduct heat.

  The first cooling flange 70 has a hollow donut plate shape, and has an inner diameter through which both the second cooling stage 32 and the fins 34 of the refrigerator 30 can be inserted from above. The outer edge portion of the first cooling stage 31 of the refrigerator 30 and the inner edge portion of the first cooling flange 70 come into contact with the refrigerator 30 inserted inside the first cooling flange 70. Both are connected so as to be able to conduct heat. Therefore, in this connection state, the first cooling stage 31 can cool the heat shield body 16 to an appropriate temperature via the first cooling flange 70 and the heat conductor 72.

  The first cooling stage 31 is provided with a through hole (not shown) for inserting a temperature measurement sensor, and a purge gas, which will be described later, flows from below to above through the through hole. Yes.

  The sleeve 48 surrounds a space from the first cooling flange 70 to a through hole 74 provided in the top wall of the containment vessel 14, and the upper end of the sleeve 48 is the first cooling flange. 70 is connected in close contact with the lower surface of the outer peripheral portion, and the lower end is connected in close contact with the peripheral portion of the through hole 74 in the top wall of the storage container 14.

  Here, the length dimension of the refrigerator 30 is a state in which the refrigerator 30 is inserted until the first cooling stage 31 comes into contact with the first cooling flange 70 (hereinafter referred to as “refrigerator inserted state”). )), The fin 34 at the lower end of the refrigerator 30 is set to enter the intermediate position of the sleeve 48 into the sleeve 48. Therefore, the space above the intermediate position (the space in the sleeves 44, 46, 48) is a refrigerator insertion space.

  The diameter of the lower portion of the sleeve 48 is locally reduced at a portion located below the fins 34 in the refrigerator insertion state (that is, a portion below the portion constituting the refrigerator insertion portion). A communicating portion 76 having a shape is formed. The communication portion 76 surrounds a communication passage 78 that communicates the refrigerator insertion space above the communication portion 76 and the space in the storage container 14. Set smaller than the minimum flow path cross-sectional area in the refrigerator insertion space when the refrigerator is inserted (that is, the minimum value of the area between the outer surface of the refrigerator 30 and the inner surface of the sleeve 48 when viewed from above and below). Has been.

  As a feature of this cryogenic apparatus, a purge gas introduction pipe 80 is provided along the refrigerator 30, and the refrigerator 30 and the purge gas introduction pipe 80 are integrally inserted into and removed from the refrigerator insertion space as a refrigerator unit. It has become so.

  The purge gas introduction pipe 80 is for introducing a purge gas into the refrigerator insertion space from the outside of the apparatus to form a purge gas flow from the storage container 14 side toward the outside of the apparatus. It is wrapped around

  An intermediate portion of the purge gas introduction pipe 80 passes through the first cooling flange 70. The upper portion of the pipe 80 passes through the refrigerator supporting flange 50 and is led out of the apparatus, and a valve 82 is provided at the upper end (gas inlet end) thereof. A purge gas supply source (for example, a helium gas cylinder) (not shown) is connected to the valve 82. On the other hand, the lower end portion of the purge gas introduction pipe 80, that is, the gas discharge portion 84 is rotated further below the fin 34, and is rotated approximately 180 ° at this position and directed upward (that is, toward the outside of the apparatus). It has become a state.

  The purge gas introduction pipe 80 is preferably a small-diameter hollow pipe made of a material having a low thermal conductivity (for example, stainless steel). The purge gas may be any low boiling point gas that does not solidify at the temperature in the refrigerator insertion space during normal operation, but helium gas is generally desirable.

  On the other hand, one end of an exhaust pipe 86 passes through the refrigerator supporting flange 50 at a position different from the purge gas introduction pipe 80, and a check valve 88 is provided at the other end of the exhaust pipe 86. . The check valve 88 is opened only when the pressure in the refrigerator insertion space is higher than the atmospheric pressure by a certain pressure or more, and releases the gas in the refrigerator insertion space to the outside. To keep the value below a certain level.

  Further, a bypass pipe 90 having a valve 92 is branched from the purge gas introduction pipe 80 outside the apparatus, and is connected to the inner space of the sleeve 44. That is, a portion of the purge gas introduction pipe 80 located outside the apparatus can communicate with the vicinity of the apparatus outside side end portion of the refrigerator insertion space via the bypass pipe 90. The role of the bypass pipe 90 will be described in detail later.

  Further, this cryogenic device is provided with a valve body 94 for opening and closing the communication passage 78 and an operation rope 98 for operating the valve body 94 from the outside of the apparatus.

  The valve body 94 is disposed in the sleeve 48 so as to be movable up and down at a position directly above the top wall of the storage container 14. The valve body 94 is formed of a material having high thermal conductivity such as copper, and its upper surface has a conical shape. On the other hand, a portion of the sleeve 48 immediately below the communication portion 76 is a valve seat portion 96 having a conical inner surface that can be brought into close contact with the upper surface of the valve body 94. The valve seat portion 96 and the valve body 94 Due to the close contact, the communication path 78 and the space in the storage container 14 are blocked.

  It is more preferable to provide a seal layer made of a metal material that is more easily elastically deformed than the material constituting the valve body 94 at a portion where the valve body 94 is in close contact with the valve seat portion 96. As this seal layer, for example, a laminate of a solder layer and an indium layer is suitable.

  The lower end of the operation cord 98 is connected to the apex portion of the valve body 94, and the valve body 94 is held in a suspended state. The operating cord 98 is guided upward along the refrigerator 30 from the valve body 94 and led out of the apparatus through a guide tube 100 extending outward from the sleeve 44. The operation plate 102 is fixed to the main body. A tension spring 104 is interposed between the operation plate 102 and the end of the guide tube 100. Then, the upper surface of the valve body 94 is separated downward from the valve seat portion 96 as shown in the state in which the tension spring 104 is not pulled and deformed, and against the urging force of the tension spring 104 from this state. When the operation plate 102 is pulled up, the length of the operation cord 98 is set so that the valve element 94 is pulled upward and the upper surface of the valve element 94 is in close contact with the valve seat portion 96. .

  The operation cord 98 is routed so as to bypass the refrigerator 30 so that the pulling operation can be performed even if the refrigerator 30 is inserted into the refrigerator insertion space. In order to maintain the routing state, a guide 106 for guiding the operating rope 98 is provided at a suitable position on the inner surface of the sleeves 44, 46, 48.

  Next, the usage point of this cryogenic apparatus will be described.

  First, normal operation is performed in the following state.

  1) A state where the refrigerator 30 is inserted at a regular position in the refrigerator insertion space is set. Specifically, the first cooling stage 31 of the refrigerator 30 is connected to the first cooling flange 70 so as to allow heat conduction, and the press-fit portion 54 of the refrigerator support flange 50 is press-fitted inside the upper end portion of the sleeve 44. To do. Further, the flange portion 52 of the flange 50 is fixed to the screw rod 62 of the height adjusting mechanism 60 at an appropriate height position. Specifically, the flange portion 52 is placed on the height adjusting flange 64 supported by the lower nut 66 on each screw rod 62, and the upper nut 68 is fastened and fixed thereto.

  2) The valve plate 94 is kept in the illustrated valve opening position (position away from the valve seat portion 96) without operating the operation plate 102.

  3) The valve 82 of the purge gas introduction pipe 80 is closed and the valve 92 of the bypass pipe 90 is kept open.

  In this state, when the refrigerator 30 reaches a steady operation, the first cooling stage 31 of the refrigerator 30 cools the heat shield body 16 to an appropriate temperature through the first cooling flange 70 and the heat conductor 72, and The 2nd cooling stage 32 of the refrigerator 30 will be in the state which cools the fin 34 to about 4K. Therefore, even if the refrigerant gas generated by the evaporation of the refrigerant 12 in the storage container 14 rises through the through-hole 74 and the communication path 78 of the container 14, the gas is regenerated by contacting with the fins 34. It will be condensed and reduced into the containment vessel 14, thereby significantly reducing the consumption and replenishment frequency of the refrigerant 12.

  On the other hand, when performing maintenance (for example, periodic maintenance) of the refrigerator 30, the operation of the refrigerator 30 is temporarily interrupted, and the refrigerator 30 is extracted from the refrigerator insertion space, and a new refrigerator 30 is obtained. Is required to be inserted into the refrigerator insertion space and restarted. This operation is performed according to the following procedure.

  1) The upper surface of the valve body 94 is brought into close contact with the valve seat portion 96 by pulling the operation plate 102 connected to the operation cable body 98 upward against the elastic return force of the tension spring 104. As a result, the inside of the storage container 14 is cut off from the refrigerator insertion space above the valve body 94, so that the purge gas flows into the storage container 14 even if a purge gas described later is introduced into the refrigerator insertion space. Is prevented. In addition, since the flow passage cross-sectional area of the communication passage 78 immediately above the valve body 94 is smaller than the minimum flow passage cross-sectional area in the refrigerator insertion space, even if the valve closing operation of the valve body 94 is defective. The purge gas is effectively prevented from flowing into the storage container 14 through the communication passage 78.

  2) By closing the valve 92 of the bypass pipe 90 and opening the valve 82 of the purge gas introduction pipe 80, the purge gas is introduced into the refrigerator insertion space through the purge gas introduction pipe 80. Specifically, the purge gas is discharged upward from the gas discharge portion 84 at the lower end of the purge gas introduction pipe 80 at a position below the fins 34 of the refrigerator 30. When the pressure in the refrigerator insertion space exceeds a certain level due to the introduction of the purge gas, the check valve 88 of the exhaust pipe 86 is opened. As a result, an upward purge gas flow is formed from the gas discharge part 84 to the check valve 88 through an opening (not shown) of the second cooling stage 32 (that is, from the storage container 14 side to the outside of the apparatus). Is discharged to the atmosphere through the exhaust pipe 86 and the check valve 88 while gradually warming the entire refrigerator 30.

  3) When the temperature in the vicinity of the second cooling stage 32 and the fins 34 rises to an appropriate temperature (for example, a temperature equal to or higher than the boiling point of oxygen), the introduction of the purge gas is continued, and the refrigerator 30 is inserted into the refrigerator insertion space. Pull out from the inside to the outside of the device (ie upward). Accordingly, the refrigerator supporting flange 50 and the exhaust pipe 86 fixed to the refrigerator 30 and the purge gas introduction pipe 80 wound around the refrigerator 30 are also integrated with the refrigerator 30 outside the apparatus. Pull up. At that time, the purge gas introduction pipe 80 and the bypass pipe 90 are separated in advance.

  In this way, by pulling out the refrigerator 30 while forming a purge gas flow, it is possible to effectively suppress the flow of air, water vapor, or the like from the outside of the apparatus into the refrigerator insertion space during the pulling out.

  Here, when the purge gas is mistakenly mixed with a high freezing point impurity (for example, water or carbon dioxide) of a certain level or more, this impurity may solidify and cause the purge gas introduction pipe 80 to be blocked. In order to release the blocked state, it is necessary to raise the temperature in the purge gas introduction pipe 80 to vaporize the solidified impurities. At this time, if the purge gas introduction pipe 80 is fixedly connected to, for example, the sleeve 48 as shown in FIG. 2 as a comparative example, the object to be cooled 10 is heated in order to heat the purge gas introduction pipe 80. As a result, the entire cryogenic device must be shut down with a temperature rise of a large amount of time, and enormous time and cost are required for the subsequent startup. In particular, when the object to be cooled is the superconducting magnet 10 as described above, it must be demagnetized once, and the time required for the restoration becomes extremely long.

  On the other hand, in the cryogenic apparatus shown in FIG. 1, the purge gas introduction pipe 80 is provided along the refrigerator 30, and both are integrally pulled up from the refrigerator insertion space. Even if the above-described blockage occurs in 80, the operation of the entire cryogenic apparatus is not stopped, and the purge gas introduction pipe 80 can be recovered (heating, etc.) outside the apparatus main body.

  4) After extracting the refrigerator 30 as described above, the new refrigerator 30 is quickly set in the refrigerator insertion space and returned to the state before extraction. That is, the valve 82 of the purge gas introduction pipe 80 is closed, the valve 92 of the bypass pipe 90 is opened, and the valve body 94 is lowered to the valve open position. And the said refrigerator 30 is started and it transfers to a steady state.

  At this time, the bypass pipe 90 plays the following role.

  After the refrigerating machine 30 is restarted, when the steady state is reached and the temperature of the recondensing chamber becomes around 4K, helium gas having a temperature distribution from room temperature to near absolute zero is inside the purge gas introduction pipe 80. To charge. In such a pipe filled with a gas having a large temperature gradient, a thermoacoustic vibration of the gas occurs and a very large heat transfer occurs, resulting in a large heat inflow toward the recondensing chamber (for example, superconductivity).・ Refer to Cryogenic Engineering Handbook, edited by Cryogenic Engineering Association). However, by making the purge gas introduction pipe 80 communicate with a large volume space such as a refrigerator insertion space through the bypass pipe 90, generation of the thermoacoustic vibration can be effectively suppressed.

  FIG. 3 shows data that clearly represents the effect of the bypass pipe 90. The right vertical axis of the graph shown in the figure shows the amplitude and frequency of pressure oscillation in the purge gas introduction pipe 80 measured at the position of the valve 82 provided in the purge gas introduction pipe 80, and the left vertical axis shows the refrigerator 30. The temperature of the 2nd cooling stage 32 and the liquid level temperature of the refrigerant | coolant 12 (liquid helium) are shown, and the horizontal axis has shown time.

  As shown at the left end of the figure, when the refrigerator 30 is in a steady state, the internal pressure of the storage container 14 is equal to or lower than the atmospheric pressure, and the liquid surface temperature of the refrigerant 12 is about 4K. Here, when the valve 92 is closed and the bypass pipe 90 is closed, the amplitude and frequency of the pressure fluctuation rapidly increase, and the temperature of the second cooling stage 32 rapidly increases. This is presumably because a large amount of heat was input to the second cooling stage 32 and the fins 34 due to thermoacoustic vibration generated in the purge gas introduction pipe 80. Thereafter, when the valve 92 is opened to bring the bypass pipe 90 into a communicating state, the temperature of the second cooling stage 32 is quickly restored.

  In the present invention, the bypass pipe 90 is not essential, and may be appropriately omitted depending on the inner diameter and length of the purge gas introduction pipe 80. Further, the small cross-sectional area communication portion 76 and the valve element 94 that are means for suppressing the inflow of the purge gas to the storage container 14 may not necessarily be provided, either one may be provided, or both may be omitted. May be. When the valve body 94 blocks the flow path on the storage container 14 side, an upward purge gas flow is formed as a result even if the lower end portion (gas discharge portion 84) of the purge gas introduction pipe 80 is directed downward. Is possible.

  A second embodiment of the present invention is shown in FIG.

  Although the apparatus shown in FIG. 1 cools the object 10 to be cooled by immersing it in the refrigerant 12, the apparatus according to the second embodiment is directly cooled by the refrigerator 30 without using the refrigerant. It is a refrigerant-free system that cools the body 10. In this apparatus, the heat shield body 16, the fins 34, and the small cross-sectional area communication portion 76 shown in FIG. 1 are omitted, and the second cooling stage 32 of the refrigerator 30 is directly connected to the body to be cooled 10. .

  In addition, a sleeve (refrigerator insertion portion) 110 is installed in a region extending from the upper surface of the superconducting magnet 10 to the outside of the apparatus through the top wall of the vacuum vessel 18, and a refrigerator insertion space is provided inside the sleeve 110. Is formed.

  Also in such an apparatus, when maintenance of the refrigerator 30 is performed, purge gas is introduced into the refrigerator insertion space in the sleeves 44, 46, 48 through the purge gas introduction pipe 80 wound around the refrigerator 30. By pulling up the refrigerator 30 while forming an upward purge gas flow, the refrigerator 30 can be replaced while effectively suppressing the flow of outside air into the refrigerator insertion space. Similarly to the first embodiment, by pulling up the purge gas introduction pipe 80 together with the refrigerator 30, even if the purge gas introduction pipe 80 is blocked, the operation of the entire cryogenic apparatus is not stopped. The purge gas introduction pipe 80 can be restored.

  In the present invention, the purge gas introduction pipe 80 does not necessarily have to be wound around the refrigerator 30, and may be piped substantially linearly along the refrigerator 30, for example. However, if the purge gas introduction pipe 80 is wound around the refrigerator 30 as shown in the figure, the introduction pipe 80 is unlikely to be separated from the refrigerator 30, and the purge gas introduction pipe 80 is caught by the first cooling flange 70 and the like. There is an advantage that the inconvenience can be avoided more reliably. Alternatively, the purge gas introduction pipe 80 may be incorporated in the main body of the refrigerator 30.

  In the present invention, the specific configuration of the refrigerator 30 is not limited, and may be, for example, a single-stage refrigerator.

It is sectional drawing which shows the principal part of the cryogenic device concerning the 1st Embodiment of this invention. It is sectional drawing which shows the principal part of the cryogenic apparatus concerning the comparative example of this invention. It is a graph showing the generation | occurrence | production state of the thermoacoustic vibration resulting from a purge gas introduction pipe when there is no bypass pipe. It is sectional drawing which shows the whole structure of the cryogenic device concerning the 2nd Embodiment of this invention. It is sectional drawing which shows an example of the conventional cryogenic apparatus.

Explanation of symbols

10 Solenoid superconducting magnet (cooled object)
DESCRIPTION OF SYMBOLS 12 Refrigerant 14 Storage container 16 Heat shield body 18 Vacuum container 20 Magnetic field utilization space 30 Refrigerator 31 1st cooling stage 32 2nd cooling stage 34 Fin 44, 46, 48 Sleeve (refrigerator insertion part)
70 First cooling flange 76 Communication part 78 Communication path 80 Purge gas introduction pipe 82 Valve 84 Gas discharge part 86 Exhaust pipe 88 Check valve 90 Bypass pipe 92 Valve 94 Valve body 96 Valve seat part 98 Operation cord body 102 Operation plate 104 Tension spring (biasing means)
106 Guide 110 Sleeve (Refrigerator insertion part)

Claims (18)

In a cryogenic apparatus comprising a storage container for storing a body to be cooled, and a refrigerator that generates cold that contributes to cooling the body to be cooled stored in the storage container.
A refrigerator insertion portion surrounding a refrigerator insertion space that is connected to the inside of the containment vessel and the outside of the apparatus and into which the refrigerator can be inserted from the outside of the apparatus;
A purge gas for preventing outside air from flowing into the refrigerator insertion space when the refrigerator is pulled out from the refrigerator insertion space to the outside of the apparatus is introduced into the refrigerator insertion space from the outside of the apparatus. A purge gas introduction pipe for forming a purge gas flow from the storage container side toward the outside of the apparatus,
The cryogenic apparatus is characterized in that the purge gas introduction pipe is provided along the refrigerator and is inserted into and removed from the refrigerator insertion space together with the refrigerator.   2. The cryogenic apparatus according to claim 1, wherein the containment vessel stores a liquid refrigerant for cooling the object to be cooled, and the object to be cooled is immersed in the refrigerant. A cryogenic apparatus for storing, wherein the refrigerator recondenses the refrigerant gas generated by evaporation of the refrigerant in the storage container in the refrigerator insertion space.   3. The cryogenic apparatus according to claim 2, wherein a gas discharge port of the purge gas introduction pipe is disposed in the refrigerator insertion space so as to face the outside of the apparatus at a position deeper than an end in the insertion direction of the refrigerator. A cryogenic device characterized by being made.   2. The cryogenic apparatus according to claim 1, wherein the refrigerator is connected to a cooled object in the storage space so as to be able to conduct heat.   The cryogenic apparatus according to any one of claims 1 to 4, wherein the purge gas introduction pipe is wound around the refrigerator.   The cryogenic apparatus according to any one of claims 1 to 5, wherein an end portion on the outside of the refrigerator insertion space is closed with a purge gas discharge passage in a state where the refrigerator is inserted into the refrigerator insertion space. A cryogenic apparatus characterized in that a check valve is provided in the purge gas discharge passage to allow only the flow of the purge gas in the discharge direction to the outside of the apparatus.   The cryogenic apparatus according to any one of claims 1 to 6, wherein the purge gas introduction pipe communicates with the vicinity of the apparatus external side end of the refrigerator insertion space via a bypass pipe having a valve. Features a cryogenic device.   The cryogenic apparatus according to any one of claims 1 to 7, further comprising gas inflow suppressing means for suppressing purge gas introduced into the refrigerator insertion space from flowing into the storage container. Cryogenic equipment.   9. The cryogenic apparatus according to claim 8, wherein the gas inflow suppression means has a communication portion that forms a communication passage that connects the refrigerator insertion space and the space in the containment vessel, and the communication passage of the communication portion. The cryogenic apparatus is characterized in that the flow path cross-sectional area of the refrigerator is smaller than the minimum flow path cross-sectional area in the refrigerator insertion space in a state where the refrigerator is inserted into the refrigerator insertion space.   10. The cryogenic apparatus according to claim 8 or 9, wherein the gas inflow suppression means operates a valve body that opens and closes a gas flow path from the refrigerator insertion space to the containment vessel, and operates the valve body from the outside of the apparatus. And a valve operating means.   11. The cryogenic apparatus according to claim 10, wherein the valve operating means is an urging means for urging the valve body in a direction in which the valve body opens the storage container side end of the refrigerator insertion space, and one end thereof. And an operating rope that is connected to the valve body and the other end is led out of the apparatus. The valve element is attached to the biasing means by pulling the operating rope from the outside of the apparatus. The cryogenic device, wherein the operation rope is routed so as to move to a position where the storage container side end of the refrigerator insertion space is closed against a force.   12. The cryogenic apparatus according to claim 11, wherein the operation cable body is placed in the refrigerator insertion space so that a pulling operation can be performed from outside the apparatus even when the refrigerator is present in the refrigerator insertion space. A cryogenic device characterized in that it is routed so as to bypass the inserted refrigerator.   The cryogenic device according to any one of claims 10 to 12, wherein a portion of the valve body that comes into contact with a counterpart valve seat portion when the valve body is closed is made of a material that constitutes the valve body. A cryogenic apparatus characterized in that a sealing layer made of a metal that is easily elastically deformed is provided. A cryogenic unit for a cryogenic apparatus including a refrigerator provided in a cryogenic apparatus having a storage container for storing an object to be cooled, and generating cold heat that contributes to cooling of the object to be cooled stored in the container. Because
The refrigerator has an outer shape that can be inserted from the outside of the cryogenic device into a refrigerator insertion space formed in the cryogenic device so as to be connected to the outside of the cryogenic device and the inside of the containment vessel. With
When this refrigerator is pulled out of the refrigerator insertion space to the outside of the apparatus, a purge gas for preventing outside air from flowing into the refrigerator insertion space is introduced into the refrigerator insertion space from outside the apparatus. A purge gas introduction pipe for forming a purge gas flow from the storage container side toward the outside of the apparatus;
A cryocooler unit for a cryogenic apparatus, wherein the purge gas introduction pipe is provided along the refrigerator and is inserted into and removed from the refrigerator insertion space together with the refrigerator.   15. The refrigerator unit for a cryogenic apparatus according to claim 14, wherein a storage container of the cryogenic apparatus contains a liquid refrigerant for cooling the object to be cooled, and the object to be cooled is immersed in the refrigerant. And the refrigerator is configured to recondense the refrigerant gas generated by evaporation of the refrigerant in the storage container in the refrigerator insertion space. Refrigerator unit for cryogenic equipment.   The refrigerator unit for a cryogenic apparatus according to claim 15, wherein a gas discharge port of the purge gas introduction pipe is disposed so as to face the outside of the apparatus at a position deeper than an end in the insertion direction of the refrigerator. A refrigerator unit for a cryogenic device characterized by that.   15. The refrigeration unit for a cryogenic apparatus according to claim 14, wherein the refrigerator is connected to a cooled object in the storage space so as to be able to conduct heat. Machine unit.   The refrigerator unit for a cryogenic device according to any one of claims 14 to 17, wherein the purge gas introduction pipe is wound around the refrigerator.

Images