DE1501283B1 - Device for cooling objects - Google Patents

Description

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The invention relates to a device for cooling the coil through the housing material to a certain extent management of objects, especially superconducting coils, minimum height required, which is located in a closed evacuable inlet To cool down the coil winding in a sol-

Set containers are located and the cryostats known by evaporation are considerable a low-boiling refrigerant, in particular liquid 5 quantities of the expensive refrigerant required, inssigen Helium, cooled down to low temperatures, especially if you are aiming for shorter cooling times, will. In the previously known cryostats for superconducting

The deep freezing of superconducting coils represents the cold content of the liquid helium only difficult technical problems both in terms of very incompletely exploited. A certain improvement simple and safe construction of the cooling from an economic point of view results if Device as well as with regard to one Wirt- one the inner one, intended for liquid helium continuous economic operation, in which the refrigerant vessel with the coil is initially consumed by liquid stick to maintain a given substance pre-cooled. However, this method is in practice low temperature should be kept low. With quite awkward to perform because of the nitrogen So-called superconducting coils, the coil winding is completely vented again before the helium is filled in must be reduced to temperatures during operation. Remaining in the bobbin half of the transition temperature of the material of the coil nitrogen residues can form ice and thus to winding to cool down. The transition temperatures of the clogging of supply and exhaust pipes Wire guides currently used for technical coils. The cryostat must therefore after cooling materials lie at around 17 to 15 ° K relative to nitrogen temperature, but they must be carefully evacuated, Relatively high, however, these leaps have to be used for longer operating times in the previously known

temperatures because of the magnetic behavior of the device required a larger supply of flüsder Materials in operation well below the level of helium causes further disadvantages. So must will. According to the state of the art, for example, in the event of a business interruption can thus be used as a refrigerant for freezing 25 liquid helium superconducting coils still in the cryostat only liquid helium can be used for vapors. Also occur in general. Further technical developments aim at greater refrigerant losses if the supradie Creation of wire materials with a considerable line coil in the normally conducting state (ohmic higher transition temperatures; however, materials are shear resistance) passes over during the imprinted with such properties for technical coils 30 still high superconducting currents in the transition interval not yet usable. is available. This results in a short-term

As is known, already gaseous helium produces strong heat, which has a corresponding a relatively expensive raw material. It results in the evaporation of the expensive refrigerant liquid costs for this gas because of tech- hat.

niche difficulties are also high, 35 Another disadvantage of conventional coil cooling methods, those who use liquid helium can be seen in the fact that it is practically impossible becomes, in general, expensive. For this is borrowed, temperatures above 4.2 ° K, the bottom of the boil arises for such freezers point of liquid helium, adjust and condense To keep the task of lowering as far as possible. According to previous experience is of refrigerant consumption. This is especially true for 40 but with a high probability to assume the cooling of superconducting coils, with which the most favorable working temperature for suprader Coil and the coil housing inevitably leading coils is above 4.2 ° K. aside from that substantial masses are to be cooled down and kept cold. may require newly developed materials A 50 kG coil with a magnetic field fulfills the setting and maintenance of higher temperatures Interior about 5 cm in diameter and about 45 fittings. On the other hand, it is known to have low tempe-28 cm in height, for example, has a mass of around ratures with the help of evaporator cryostats kg. testify, in which liquid helium from a source

According to the known technology, supermarket containers were previously conveyed into an evaporator body line coils in liquid cryostats are produced and these under evaporation to any conventional construction cooled. There are 5 ° preselectable temperature values between 4.2 ° K and the coil winding in a vacuum-insulated and room temperature cools. It is also used to cool from a nitrogen-cooled radiation protection to samples that are to be irradiated in the reactor, one given vessel, which is filled with liquid helium device known in which the sample is in a is. The coil winding is in a bath of with a liquid refrigerant, for example neon, liquid helium. The free interior space of a Zy- 55 filled insert container is located Linderspule is either also designed as a cooler from the liquid end. The cooler comes with Helium fulfills or can, in the case of a ring-shaped structure, another, boiling at a lower temperature way of the cryostat kept at room temperature refrigerant, for example hydrogen, filled, so will. Such cryostats are known in the art that the cooling literature evaporating from the insert container referred to as a »hot hole cryostat«. 60 medium recondensed and again downwards

The known cryostats have a height that drips. To accurately determine the condensation temperature of the on, which is a multiple of the coil height. to be able to set higher-boiling coolant, This unfavorable dimension ratio is provided by a heating element on the cooler. The sample the cooling principle used so far. With the help of this device you can reach a single longer operating times without refilling refrigerants 65 temperature, namely the boiling temperature of the higher too ensure, a boiling cooling medium must be brought over the coil winding, appropriate liquid level must be provided. . The invention is based on the task In addition, to avoid heat conduction, a device for cooling superconducting

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To create coils that allow the setting of variable advance in refrigerant consumption considerably more economical selectable temperatures above 4.2 ° K, and more economical than the previously known bath in which the risks resulting from the properties of supercryostats for freezing superconducting coils, line coils a minimum Furthermore, the device has the advantage that any are reduced, at which the refrigerant losses S preselectable temperatures are set above the boiling temperature of the cooling medium compared to the conventional bath cryostat technology and are substantially reduced and the simple, can be kept. It therefore enables technically safe continuous operation with optimal exposure of the respective optimal operating temperature,
use of the cold content of the liquid refrigerant to avoid a hazard during transition. The characteristic of the invention is seen from the superconducting to the normally conducting state in that the insert container via an overpressure safety device can also be advantageous to the interior of the known heat transfer medium, which is filled with the filling line and a filling device with a heat transfer medium in preferably helium, with at least approximately the type of an adjustable automatic safety constant maintenance of the pressure in the insert container on 15 valve, the response pressure of which is a little above the one preselectable constant value can be refilled, to secure the operating pressure. In the case of sudden evaporation of the heat transfer medium inside the insert container, an evaporator body is then arranged without a dangerous increase in pressure, with the circuit equalizing in a known manner, preferably after a gas collection space for the cooling medium in the evaporator body from 20 (helium recovery systems) . A pre-filling of the insert container is separate. partial structural arrangement can thereby be achieved

The refrigeration capacity of a suction line to one will be that the evaporator body is tubular Vacuum pump connected to the evaporator body coil winding at least on its outer circumference is expediently enclosed in a manner known per se. The evaporator body can be from by the suction power of the vacuum pump in a one-part or multi-part, deep-dependency known per se be surrounded by the temperature in the area of the cooled radiation protection body, weldes The throttle valve controlling the evaporator body is preferably connected to the exhaust port of the detuned (German interpretation 1161 570). steamer body is connected. In this way

The coil is located in this device - the cold content of the exhaust gas in the radiation winding is used in a protective body with the initially gaseous 30 and operation with a cooling medium only filled with heat transfer medium is enabled. The evaporator and the cooling of the heat transfer body and / or the radiation protection body can be carried out by means of an evaporator body with a separate refrigerant body, preferably located in the area of an end face, and thus also the coil winding which is expediently exchanged with it in heat from a bifilar tube winding with an exchange There are inlet and outlet openings. It appears circuit. The use of gaseous helium is also expedient; the filling line for the heat transfer medium in the deep tank is already known through thermal contact with the counter-temperature calorimetry, but the exhaust gas from the evaporator body, which flows out, is only followed by the immersion of a sample container of the radiation protection body cool. This vorers in a helium bath, whereby the sample container is used for cooling to reduce the refrigerant, neither highly evacuated or with helium as heat consumption.
Transmission medium can be filled. _ With appropriate training, the

A device according to the invention can be positioned opposite the superconducting coil in the free interior space Compact design in a relatively small space under the interior of the insert container in a gas-tight manner and does not need to be closed with liquid nitrogen 45, so that the in the interior of the cooled radiation protection. It can be used in each coil introduced samples at a higher temperature operating condition can be kept at the same temperature as the coil with just one cooling medium ("drive hot. hole"). The introduction of samples into the interior

In addition, the cooling device can be placed under the greatest possible space of the coil with the aid of a device for taking advantage of the cold content of the cold 50 sample introduction possible, which in the case of the Ermitteis (Heat of vaporization and enthalpy of the quay fill the interior with liquid helium Gas) to the desired operating temperatures, for example in the form of a gas lock be cooled down. You can flow to cool down.

siges helium as a cooling medium in the evaporator body The equipment arrangement can be used for the same. However, it can also be designed differently with only a minimal basic principle. It takes effort and without complicating the following seems favorable to choose a structure in which the helium operation is possible to use the bil vaporizer body for pre-cooling with the aid of poorly warmer liquid nitrogen. The pre-conducting mounting elements directly or below the direction have a very small dead volume. With the interposition of the radiation protection body during operational interruptions or when the transition of the 60 is held to the housing surrounding it.
An advantageous operating method for the correspondingly only slight refrigerant losses written device can be carried out in such a way that primarily through the evaporation or that the as heat transfer medium in the heating of the compared to the known bath- The inside of the insert container introduced cryostat low filling amount of the heat transfer medium 65 given at a predetermined constant pressure value in the insert container is maintained, while the heat transfer during the refrigerant loss in the evaporator circuit medium and thus the heat exchange with it is minimal. This proves the device standing coil winding through the evaporator body

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is displayed by, if necessary, until the gas 7 condenses. One as overpressure protection or vaporous heat transfer medium for the insert container 3 serving safety cooled will. The filling device valve 8 already described is also connected to the filling line 4 takes on the task of being gas-fed in each case and connects the insert container 3 with one Miges heat transfer medium in the interior 5 not shown recovery system for of the insert container, so that the pre-helium, and also can be given via a connection Pressure value is not fallen below. The valve 9 also does not connect to one The pressure value to be specified will be produced by the vacuum pump to be set, temperature determined. The pressure value is at the upper free end of the insert container 3 always over an atmosphere. io there is a connecting flange 10, which is a one-case Such a method can also bring device 11 for introducing samples into It may be expedient that the refrigerating capacity of the evaporator body, filled by the magnetic field, is the coil interior After the heat exchanger has cooled down, a sensor element 12 of the level indicator and the transfer medium carries a connection 13 of a control line 14 to the desired target temperature. With Depending on the state variables of the heat 15 aid of the sensor element 12, the fluid transmission medium in the insert container with the help of the heat that had cooled down to liquefaction Control arrangements known per se in such a way that the transmission medium in the insert container 3 can be overridden is that the temperature of the coil winding will be woken up. The sensing element 12 is functional an adjustable value at least approximately moderately designed as a resistance spiral, whose elekconstant is held. This regulation of the cold? .O Irish resistance itself when immersed in the performance allows the fluid level of the heat transfer medium to be set and kept constant changes significantly from temperatures above the boiling point.

liquid helium (4.2 ° K) as well as above the The evaporator body 2 is above a critical exhaust gas point of helium (5.2 ° K), in which outlet line 15 is also a bifilar tube area the best operating temperatures for 25 winding executed radiation protection body 16 on superconducting coils should lie. ' closed, which surrounds the insert container 3 and to reduce costs, the cooling of the exhaust gas outlet 17 with the one in the drawing Coil winding also expediently in the manner not shown in the helium recovery system in take place in stages that the evaporator body is connected to.

next with a low-boiling cooling medium of 30 The radiation protection body 16 is together with higher boiling temperature, preferably with nitrogen, the insert container 3 is so-called cooled by layers is and that then surround a th superinsulation 18, which is essentially Temperature reduction through the evaporation borrowed through several layers of thin, metallized tion of cooling medium with a lower boiling temperature can be formed in the film with an air gap. This Evaporator body takes place. 35 The interior structure is enclosed in an evacuable jacket container 19 for further thermal insulation. Device enables the most varied of structural arrangements via a shut-off valve, such as cryostats with a connecting flange 20 also with the one at position 9 not liquid helium-free interior ("hot hole") shown vacuum pump is connected, and cryostats with a horizontal coil arrangement 40. The jacket container 19 is supported by a frame 21 or also cryostats, in which the coil winding is carried, under which a storage vessel 22 for the flowing the operation from a vertical to a sige cooling medium (helium, nitrogen) is arranged. horizontal position can be pivoted. This The storage vessel 22 is assigned to an constructive possibilities were with the previously connecting flange 23 also with the one known in the drawing Bad cryostats not available. The deepening 45 not shown helium recovery cooling device with the features of the invention system in connection.

furthermore creates the basic element of the liquid level in the storage vessel 22 with high operational reliability location for a largely maintenance-free permanent a vacuum-insulated riser pipe 24 leads to the operation over longer periods of operation. Inlet connection of the evaporator tube coil the drawing is an embodiment of a 50 body 2, which is on the exhaust side of the radiation device is connected with the features of the invention see protection body 16, the exhaust gas matic shown; it shows outlet 17 via an evacuation line 25 under FIG. 1 a longitudinal section through a deep-freeze interconnection of a pressure-controlled regulating device according to the invention, the direct valve 26 and a throttle valve 27 with a white a helium storage vessel is constructed, 55 direct vacuum pump 28 serving as a feed pump F i g. 2 shows a section through the in FIG. 1 shown in connection. This further vacuum pump 28 Deep freezing device with superconducting coil in is connected on the outlet side to the already mentioned several times, in larger scale. Helium recovery not shown in the drawing

You can see a tubular superconducting system connected.

coil 1, which is connected by an evaporator body 2 in 60. The control valve 26 stands over the control line 14, which is designed as a vapor pressure form of a cup-shaped, bifilar tubular winding thermometer and which is surrounded. The superconducting coil 1 and the steam pressure and temperature measurement association 2 are located in the interior of an insert-provided display instrument 14 a connected to the container 3, which is connected to a filling line 4 with the interior of the insert container 3 in the filling device 5 connected, with their 65 bond. At this point, as an alternative, helium gas from a gas bottle 6 in the interior can also be filled with an electromagnetic control valve 26 space of the insert container 3, and instead of the filling pressure formed as a vapor pressure thermometer by a pressure measuring instrument, an electrical control line 14 Temperature

Temperature regulator with an electrical temperature measuring device in the area of the junction of the siphon connection sensor be used. tube 48 in the spiral tube is in a gas-permeable

F i g. 2 shows details of the structure of the cool-permeable envelope 50, an activated carbon filling 51

contraption. Here you can see more clearly the pots housed, which, when cooled, are

shaped, bifilar tube winding of the evaporator body- 5 improvement of the vacuum in the jacket container 19

pers 2, which is turned from a bobbin 29 one.

Coil winding 30 and centering pieces 31 together. The radiation protection body 16 carries on its set superconducting coil 1 encloses. The upper end of a tubular extension piece 52, superconducting coil 1 standing in a thermally conductive connection with it, of the evaporator body 2 and the dung standing ring-shaped extension piece 52, superconducting coil 1 are enclosed in the insert container 3 io which is preferably by means of dip soldering, the connecting piece 53 attached to a badly thermally conductive pin with a Abten32 is carried, which are held in connection piece 54 as a heat choke and a set pipe pieces 34 which are inserted into a cooled carrier plate 33 and serve as a heat choke. The cooled radiation protection tube 55 in thermally conductive connection plate 33 rests in turn on poorly thermally conductive 15 manure. The radiation protection body 16 and the support element 35, which, like the pins 32, are symmetrical radiation protection tube 55, as already shown in FIG. 1 shown metrically on the circumference of the supported components, arranged in the form of super insulation 18 and surrounded by metal-coated foils wrapped in a base plate 36,
are laid. To cool the plate 33, a spiral pipe 37, which is connected to the exhaust gas outlet 17 of the jet (see FIG. The outlet pierces through the cooled plate 33 and in a vacuum of the spiral 37 leads to a vacuum-jacketed jacketed gas supply connection flange 56, which is shown in FIG. 1 with the as det. The further vacuum pump 28 connected to the plate 33 in a soldering point 58 is connected to the feed line 4 by means of screw windings. as 57 in thermal contact with the countercurrent

The insert container 3 is at its upper end th exhaust gas of the evaporator body 2 in the exhaust gas

closed with a cover piece 39, which in the outlet line 15 and in the radiation protection body 16

a detachable dip soldering 40 is used. That arranged. The connecting flange parts 20, 38, 49 and

Cover piece 39 takes centering pieces 31 of 56 are inserted into base plate 36.

Superconducting coil 1 in a correspondingly adapted 30 for operating the device according to the invention

Centering rings 41 and also carries a from is after assembly with evacuation of the

A single-shell container 19 consisting of poorly thermally conductive material is first of all the insert container 3

transfer tube 42. evacuated. Then on the filling device 5 a

The introduction tube 42 is provided with a cover plate corresponding to the desired temperature 43 of the jacket container 19 passed and set at 35 pressure and the heat transfer one O-ring sealed closure plate 44 gas-tight medium, e.g. B. helium gas, into the insert container 3 locked. Recessed between the cover plate 43 and the. Now the evaporator body 2 Bring tube 42 is put into operation for ease of adjustment and operation, i. i.e., it is made using the as Compensating for thermal expansions a movable delivery pump serving further vacuum pump 28 binding provided, which a bellows 45 on- 40 liquid helium from the storage vessel 22 via the has, on the one hand at the upper end of the riser pipe 24 and the siphon connection pipe 48 in bring tube 42 attached end flange 10 and the tube winding of the evaporator body 2 sucked, on the other hand, it is connected to a ring piece 46, where it evaporates and the desired cooling softens in turn, gas-tight with the cover plate 43 added. The exhaust gas flows through the radiation compound is. 45 protective body 16 and the spiral pipe 37, this cools

The closure plate 44 of the feed tube 42 escapes and finally arrives via the control valve 26, the holds an O-ring screw connection 47, through which the throttle valve 27 and the further vacuum pump 28 in Sensor element 12 (see. Fig. 1) of the level indicator to the helium recovery system. With a pre-carried out can be. Also in the cooling with nitrogen, the exhaust gas is in the atmospheric cover plate 43 connections provided for the control 50 sphere.

line 14 as well as the feeding device 11 are in

the representation of FIG. 2 not shown. shaped helium in the insert container 3, but what

For connection to the refrigerant supply by automatically flowing gas from the unit Riser pipe24 (Fig. 1) is a filling device5 which is immediately balanced again. Lifter connection pipe 48 made of poorly thermally conductive 55 When the target temperature is finally reached and Material provided, which the cooled plate 33 when this temperature value is below the critical pierces and is at its upper end as the inlet temperature of the helium, so condenses in the inlet connection the tube winding of the evaporator body 2 sets container 3 the helium filling. It imagines opens into the insert container 3. At its lower liquid bath, the level of which rises, because of the At the end there is another O-ring screw 60 filling device 5 continued Helium gas replenished 49. The tube winding of the evaporator body 2 is produced. Is a setting with the sensing element 12 reaches the maximum filling level in an annular space 59 on the insert container 3. the gas from there the exhaust gas outlet line 15 leads from the inflow of the filling device 5 shut off. the poorly thermally conductive material to the inlet temperature of the helium bath in the insert container 3 The jet, designed as a bifilar tube winding, is then controlled with the help of the steam pressure treatment protection body 16. The exhaust outlet 17 of the control valve 26 by the controllable cooling capacity of the Radiation protection body 16 is on the spiral pipe 37 evaporator body 2 at the preselectable value connected. kept constant.

If operating temperatures above the critical temperature are desired, at which there is no liquid bath of the heat transfer medium arises, so is the refrigerant throughput through the evaporator body 2 and thus the temperature with the help of a through an electrical sensor via a electric regulating device controlled electromagnetic regulating valve adjust and constant to keep. Otherwise, the aspects already mentioned apply. The electrical control can itself understandably can also be used for temperatures below the critical temperature (5.2 ° K).

Claims (12)

Patent claims: 1. Device for cooling objects, in particular superconducting coils, which are in a closed evacuable insert container are and by the evaporation of a low-boiling refrigerant, in particular liquid Helium, are cooled to low temperatures, characterized in that the Insert container (3) via a filling line (4) and a filling device (5) with a per se known heat transfer medium, preferably helium, with at least approximately constant maintenance the pressure in the insert container (3) can be refilled to a preselectable constant value and that within the insert container (3) receiving the object, an evaporator body (2) is arranged, the circuit of the cooling medium in a manner known per se is separated in the evaporator body (2) from the filling of the insert container (3). 2. Apparatus according to claim 1, characterized in that a preferably adjustable safety valve (8) is provided on the insert container (3). 3. Apparatus according to claim 1, characterized in that the evaporator body (2) the enclosing tubular coil winding (30) at least on its outer circumference. 4. Apparatus according to claim 1 or 3, characterized in that the evaporator body (2) from a one-part or multi-part, deep-frozen radiation protection body known per se (16) is surrounded, which is preferably connected to the annular space (59) of the evaporator body (2) is. 5. Apparatus according to claim 1 or 4, characterized in that the evaporator body (2) and / or the radiation protection body (16) made of a bifilar tube winding with preferably im In the area of an end face there is inlet and outlet openings. 6. Device according to one or more of the preceding claims, characterized in that that the filling line (4) of the insert container (3) is cooled and preferably in thermal contact with exhaust pipes of the evaporator body (2) and / or the radiation protection body (16) is designed in countercurrent gas flow. 7. Device according to one or more of the preceding claims, characterized in that that the free interior of the superconducting coil (1) is sealed gas-tight from the interior of the insert container (3). 8. Device according to one or more of the preceding claims, characterized in that that an introduction device (11) for introducing samples into the interior of the Superconducting coil (1) is provided. 9. Device according to one or more of the preceding claims, characterized in that that the evaporator body (2) with the help of poorly thermally conductive mounting elements (32, 34) directly or with the interposition of the radiation protection body (16) in the one surrounding it Housing is supported. 10. The method for operating a freezer according to claim 1, characterized in that that the introduced as a heat transfer medium in the interior of the insert container (3) Gas is kept at a predetermined constant pressure value, while the heat transfer medium and thus the with if necessary, coil winding (30) which is in heat exchange through the evaporator body (2) cooled until the gaseous or vaporous heat transfer medium condenses will. 11. The method for operating a freezer according to claim 1, characterized in that that the cooling capacity of the evaporator body (2) after cooling of the heat transfer medium to the desired target temperature depending on the state variables of the heat transfer medium in the insert container (3) with the help of a known control valve (26) can be controlled such that the temperature of the Coil winding (30) is kept at least approximately constant at an adjustable value. 12. The method for operating a freezer according to claim 1, characterized in that that the cooling of the coil winding (30) takes place in stages in such a way that the Evaporator body (2) initially with a low-boiling cooling medium with a higher boiling temperature, is preferably cooled with nitrogen and that then a further decrease in temperature through the evaporation of cooling media with a lower boiling temperature in the evaporator body (2) takes place. For this purpose 2 sheets of drawings