DE3127796C2 - Device for producing and dispensing a body from a material that has solidified by cooling - Google Patents

Abstract

A device for generating and controlled ejection of bodies from a material solidified by cooling, in particular hydrogen pellets for injection into a plasma-physical apparatus, a fusion reactor or the like. Contains an extrusion cryostat and a storage cryostat, the temperatures of which can be set independently of one another. The solidified material is extruded at a relatively high temperature suitable for extrusion from the extrusion cryostat into the storage cryostat, where it is cooled to a lower temperature which is suitable for ejection and ensures high strength. The device preferably contains a double piston, which serves as a whole for extrusion and contains a coaxially guided ejection piston of smaller diameter, by means of which the extruded material can be ejected from the storage cryostat at the desired speed. Freezing of the extruded material in the storage channel of the storage cryostat is prevented by a heater with a short time constant, with which the wall of the storage channel can be briefly heated to allow the solidified material to be properly ejected without it being significantly heated inside.

Description

characterized in that the cooling device (64) of the channel (76) of the receiving device ( T2) is designed for further cooling of the body from the outside, and that an ejection piston (18) is provided for the controlled ejection of the body from the channel (76)

2. Device according to claim 1, characterized in that the channel (76) additionally has a heating device (90) for controlled ejection of the body

3. Apparatus according to claim 1 or 2, characterized in that the ejection piston (18) is guided coaxially in an extrusion piston (16) arranged in the freezer cryostat (Tl), t

4. Device according to one of the preceding claims, characterized in that the channel (76) of the receiving device (T2) has a polygonal, in particular square, cross-section

5. Device according to one of the preceding claims, characterized in that the outlet opening (78) of the channel (76) of the receiving device (Tl) has a narrowed brake sleeve (80).

6. The device according to claim 2, characterized in that the channel (76) of the receiving device (T2) is formed by a cooling rod (74) which is in limited thermal contact with the cooling device (64) in the receiving device, and that the heating device (90) is arranged in the cooling rod (74).

7. Device according to one of the preceding claims, characterized in that the channel (76) for safe, direct receiving of the body extruded from the extrusion nozzle through a heat insulating bracket (47,48,50) with adjustable Distance at the extrusion nozzle-side end of the freezer cryostat equiaxed one behind the other is held

The present invention relates to a device according to the preamble of claim 1.

For refilling plasma and fusion machines it is intended to solidify the required hydrogen by cooling and the resulting solid bodies ("hydrogen pellets") through ultracentrifuge or to introduce other closing devices into the reaction space (see e.g. C. T. Chang et al "The Feasibility of Pellet Re-Filling of a Fusion Reactor", Nuclear Fusion, Vol. 20, No. 2 (1980) and S. L. Milora "Review of Pellet Fuelling", Journal of Fusion Energy, VoL 1, no. 1 (1981)). With larger fusion machines qyasi-continuous refilling over several seconds or longer is likely to be required. The fast provision and acceleration of the hydrogen pellets is still unresolved Problem.

ίο One has tried this problem using faster Dissolve extrusion of solid hydrogen. However, this method has proven to be inadequate because the Extrusion cannot be carried out quickly enough and in a sufficiently reproducible manner in terms of time. aside from that are the rod-shaped hydrogen pellets produced by rapid extrusion due to the for the extrusion required, relatively high temperature inevitably of low dimensional stability Since the Introduction of the hydrogen pellets into a centrifuge only for a short time because of the required accuracy Distance, a significant after-cooling by evaporation is not possible.

A device for producing individual pellets from frozen deuterium is from J. Phys. E: Be. Instrument, Volume 13, 1980, pp. 1170-1176, known This device contains an Ey.trusionskryostat with a chamber, in which the deuterium is solidified by cooling with liquid helium. The solidified deuterium is then extruded through an extrusion nozzle by means of a piston From the extruded deuterium rods the individual pellets are cut off by heatable cutting wires, which are then brought into the focus area falling from a laser beam. Also because of the relatively high temperature required for extrusion the pellets produced with this known device have a relatively low mechanical strength and are suitable therefore not for an acceleration by a centrifuge or other Einsußvor direction.

From US-PS 40 17 578, from which the invention is based, a device for generating deuterium pellets is finally known, which contains a so-called thread source, which is followed by a rotating cutting device and a receiving device, which is cooled with liquid nitrogen and a collecting funnel contains this subsequent pellet collimator. The pellet collimator consists of a tubular channel, cooled with liquid nitrogen, through which the pellets measuring approximately 25 μm to 75 μm in diameter fall into a laser combustion chamber. The Faso denquelle contains a vessel filled with liquid deuterium, the bottom of which has an extrusion opening that tapers towards the outside. The deuterium flowing out of this opening into a subsequent vacuum space cools down through the evaporation, so that it finally solidifies.The pressure acting on the liquid deuterium is selected with regard to the dimensions of the extrusion opening so that the solidification front forms somewhat within the tapering opening and a thin thread of solidified deuterium continuously emerges from the opening.

The hydrogen pellets produced with this known device are also unsuitable for acceleration by a centrifuge, since the temperature of the pellets, due to the way they are produced, is hardly below that The freezing point lies and is further increased by the much warmer collecting funnel and collimator and the exit of the pellets from the collimator cannot be timed.

The present invention is accordingly based on the object of a device for generating and dispensing a body of a cooling solidified material, e.g. B. hydrogen to indicate the allows a largely free temperature selection of the solidified body independent of the extrusion process, so that a high dimensional stability of the body and thus a high mechanical strength is guaranteed that enable reproducible ejection.

In a device of the type mentioned at the outset, this object is achieved according to the invention by the characterizing features Features of claim 1 solved.

Developments and advantageous configurations of the device according to the invention are the subject matter of subclaims.

The device according to the invention enables the solidified material with one of the extrusion To provide independent, lower temperature available, so that the body produced a high mechanical Has solidity and can be ejected at the required speed and timing can.

In the following, a preferred embodiment of the device according to the invention is referred to explained in more detail on the drawing. It is shown in

F i g. 1 is an axial section, shown somewhat schematically, of a preferred embodiment of the present invention Device for generating and controlled ejection of rod-shaped bodies from hydrogen serves;

F i g. 2 shows an enlarged, somewhat more precisely represented axial section of part of the device according to FIG. 1; F i g. 3 a view in a plane IH-III of FIG. 2;

4 shows an axial section of a coaxial piston arrangement the device according to FIG. 1;

5 shows a cross section in a plane V-V of FIG. 1;

6 is an enlarged cross-sectional view of part of FIG. 5;

F i g. 7 is a side view of a cooling rod contained in the device according to FIG. 1;

F i g. 8 is a partially sectioned, partially broken away, enlarged view of the cooling rod according to FIG Fig. 7;

9 is a plan view of the cooling rod according to FIG. 8th;

Fig. 10 is a cross-section in a plane X-X of FIG F i g. 8, and

F i g. 11 is a cross-sectional view of parts of the Cooling rod according to FIG. 7 before assembling.

The device shown in the drawings consists essentially of two cooling heads Ti and T2, which are arranged coaxially one behind the other (FIG. I). In order to be able to set the two cooling heads to different temperatures from one another, they are largely thermally separated from one another. The device shown in the drawing has the purpose of solidifying hydrogen gas by cooling, extruding the solidified hydrogen into a storage room, storing the extruded material there and finally, if necessary, expelling it quickly and in a precisely controlled manner in terms of direction and speed. In practice, this requires an operating temperature range of approx. 3 K to 20 K. The cooling head Ti , including the required radiation shields and operating aids, forms a freezing cryostal which, in the preferred embodiment of the invention described below, is designed as an extrusion cryostat, i.e. the solidified hydrogen is pressed out ("extruded") as a strand through a nozzle with a narrowed cross-section with plastic deformation. The cooling head T2 forms a storage cryostat with the radiation shields and operating aids. The extrusion cryostat forms a unit with its fastening devices, the supply lines necessary for operation and a vacuum vessel connection flange 10. The storage cryostat lies in the extension of an extrusion nozzle 12 of the extrusion cryostat.

The distance between the two cryostats is advantageously adjustable. The extrusion and the ejection the hydrogen rod takes place by means of a coaxial piston arrangement 14, which is an extrusion piston 16 and an ejector piston 18 contains (Figure 4). The extrusion head is via an operating rod 20 can be operated from the outside. The operating rod 20 has an axial bore in which a second operating rod 22 for actuating the ejection co. ' v «ns 18 arranged The operating rods 20 and 22 can in practice by not shown, for. B. electromagnetic Drives can be moved axially.

In detail, the device shown is constructed as follows:

A tubular, vacuum-tight housing 24 is connected to the connection flange 10, from the end face of which a cylindrical extension 26 protrudes inward. The cylindrical extension 26 forms a cylindrical cavity with a base 28 to which the cooling head Ti is connected via a mounting tube 30. The actuating rod 20 for the extrusion cylinder 16 is guided by means of a collar 32 in the extension 26 and sealed by a corrugated metal pipe or a bellows 34, the ends of which are tightly connected to the extension 32 or the base 28. The conditioning pipe is connected to a hydrogen gas inlet line 36. The lower part of the actuating rod 20 with the coaxial column arrangement is guided in the holding tube 30.

The lower end of the holding tube 30 is connected in a vacuum-tight manner to a first cooling head body 38 which belongs to the cabbage head Ti . A first temperature sensor 40 is located at the upper end of the first cooling head body 38. At the lower end, the cooling head body 38 has a laterally projecting flange 42, on the outer edge of which an inner radiation shield 44 is attached.

The cooling head T2 contains a second cooling head body 46 which is fastened to the flange 42 via a connecting device with low thermal conductivity. The in F i g. The adjustable connecting device shown in more detail in FIG. 2 contains three bolts made of stainless steel chrome, one of which is shown in FIG. 2 shows a stainless steel tube 47, a ring 48 carried by the bolts and made of a plastic with poor thermal conductivity, such as polycarbonate, and three sets of fastening tips 50 made of stainless steel, with which the second cooling head body 46 is clamped to the insulating ring 48. The fastening tips 50 simultaneously allow an adjustment of the position of the second cooling head body 46 with respect to the first cooling head body 38 and thus a safe introduction of the relatively soft hydrogen rod emerging from the extrusion nozzle 12 into the channel of the pre-atskryostat.

The first cooling head body 38 is externally connected to a cooling coil 52, the inlet of which is connected to a cooling medium inlet line 54 connected. The end-

Passing end of the cooling coil 52 is connected to a cooling coil 56, which is on the inside of an outer Radiation shield 58 is attached and with its output end to a refrigerant output line 60 is connected. A heating device 62 is also provided in the first cooling head body 38.

The second cooling head body 46 (FIG. 2) contains a helical cooling channel 64, of which the extrusion nozzle 12 facing away input end via a stainless steel coiled tubing 66 with the cooling medium input line 54 is connected. while its output end (in Fig. 2 above) via a second stainless steel coiled tubing 68 with a second refrigerant outlet line 70 is connected. The circuit of the cooling channel 64 and the tube coils 66.68 is from FIG. I can be seen. At the end of the second cooling head body facing away from the extrusion nozzle 12 46 is a cup-shaped inner diffuser screen 72 attached, the dodes of which has a central opening, of the edge of which is a cylindrical one Approach 72a through a hole in the bottom of the outer radiation shield surrounding the entire arrangement 58 protrudes.

A cooling rod 74 is arranged in the interior of the second cooling head body 46, which can be illustrated with reference to FIGS. 7 to 11 will be explained in more detail. The cooling rod 74 forms a storage channel 76 which is square in cross section. which has a funnel-shaped inlet end 76a facing the extrusion nozzle 12 and in alignment therewith and at the other end forms a discharge nozzle 78 which is provided with a brake sleeve 80. On the cooling rod 74, a temperature sensor 82 is connected in the vicinity of the discharge nozzle 78. Another temperature sensor 84 is at the flange-like widened end of the second cooling head body 46 with which the inner radiation shield 72 is connected, arranged

As shown in FIGS. 7 to 11 can be seen, has the Kühlsiab a substantially rectangular cross-section. Its outside forms raised, strip-shaped contact zones 86, which rest on the inner wall of the cooling head body 46 and through milled, recessed zones 88 are separated. It consists of two parts (Fig. 11), between which a meander-shaped heating coil 90 made of an electrical jacket heating conductor is hard soldered.

The brake sleeve has an opening of circular cross section, the diameter of which is slightly smaller than the side length of the supply channel 76 and in the case of a supply channel side length of 1.1 mm z. B. can be 1.0 mm.

A further temperature sensor 92 is arranged on the end of the second cooling head body 46 facing the cooling head Ti

The first cooling head body 38 forms a condensation space 39 which ends in the extrusion nozzle 12

functionality

The cryostats work on the principle of evaporator cryostats. The refrigerant, e.g. B. liquid helium, is first introduced via the refrigerant inlet line 54 into the cooling head Ti , where it evaporates, causes the cooling and is carried away via the outer radiation shield 58 using the enthalpy of the helium gas through the refrigerant outlet line 60. For cooling of the cooling head 7 "2, a Tei! Of the by-Kähemittei Eingangsieitung is diverted 54 refrigerant supplied and guided via the separate, second coolant output line 70 to the outside. The Kälte.-nitteidurchsatz in the cooling heads Ti and Tl may be about metering valve 94 or Set 96 "in the refrigerant outlet. In addition, the cooling heads are provided with electrical heating devices 62 and 90, with the aid of which it is possible to fine-tune the required temperatures.

With the coaxial piston 14 pulled up and the cooling head Ti sufficiently cooled, the hydrogen gas is first condensed and solidified in the condensation space 39. The hydrogen gas is supplied by means of the inlet line 36 through the warm area of the apparatus. If the condensation chamber 39 is filled with solid hydrogen, the coaxial piston with retracted ejection piston 18 is placed on the solid hydrogen and this is then slowly transferred from the extrusion nozzle S2 under suitable pressure and suitable heating of the cooling head 7 "! In the form of a hydrogen rod Vnrratskänäi 76 of the second bald head TI cxlrudiurs. If the cooling head T2 is now brought to a suitable storage temperature, which is lower than the extrusion temperature, the hydrogen rod can thread into the storage channel 76 and fill it in its entire length. After further heating of the cooling head Ti (Expulsion or softening of the remaining hydrogen in the condensation chamber 39), it is possible to slowly introduce the ejection piston 18 through the extrusion nozzle 12 into the storage channel the demand rth speed continuously or intermittently ejected through the discharge nozzle 78 from the supply channel.

The cross section of the supply channel 76 is square, so that the cylindrical hydrogen rod 98 (FIG. 6) ideally only touches the wall of the supply channel 76 in four lines in order to freeze solid if possible to prevent. Adhesion of the hydrogen rod to the walls of the supply channel 76 can lead to a Deformation or destruction of the hydrogen launder, an inadequate timing of the transport and / or a blockage of the ejector piston 18 lead. Such disturbances are avoided by the quick electrical heating with the heating coil 90, so that proper ejection is guaranteed. A heating of small time constant is thereby achieves that the cooling rod 74 forming the supply channel 76 has a small heat capacity and due to the relatively narrow contact zones 86 only in

so limited thermal contact with the intermediate Cooling head body 46 is standing. As a result of the quickly responding and only briefly switched on heating it can be achieved that a temperature increase occurs only at the points of the hydrogen rod 98, which rest on the wall of the cooling channel 76 and adhere to it, while the interior of the hydrogen rod 98 on the other hand, because of the poor thermal conductivity of hydrogen, as cold as possible and thus during remains dimensionally stable throughout the ejection time

The dimensional stability of the hydrogen bearings is due to the centrifugal constraining forces that occur during their acceleration are of decisive importance.

The transport of the condensed material from the freezer thermostat to the storage thermostat is not limited to extrusion processes associated with a reduction in cross-section. The cross section of the Rather, the nozzle 12 can be the same as the cross section of the chamber 39, so that the solidified in the chamber 39

7 8 i

te material without deformation from the chamber into the ',>

Storage channel 76 is transported. The described. · ';

Apparatus can be simplified to the effect that

a column frozen out in the extrusion cryostat consisting of '.'. '

D? -I: is by a simple piston with no transverse 5 H

visual change in the storage cryostat pressed i-j

where the Dj ice cream does not freeze and then with the fvj

ei -. 'jchen piston can be ejected quickly, oh- | j

nc that a nimble heating in the storage cryostat required ^

is borrowed. IO ||

The adjustability of the distance between extru- p

sion cryostat and storage cryostat (see Fig. 2) is before |

Partly, it serves to adapt the temperature of the extruded rod to that of the storage cryostat in order to prevent freezing in it as far as possible. The | 5 relatively warm extruded / .. B. D2 from existing rods cools by evaporation so far as from until the present in the vacuum D2 partial pressure corresponding GleichgewichistciTipcratiir is reached. Of course, this is only an approximation and the better the further away the threading rod zone is from the relatively warm extrusion nozzle.

The adjustable distance between the extrusion cryostat and the storage cryostat thus has a similar function like the linear guidance in the storage cryostat. namely to prevent freezing if possible.

The present device can be used wherever there is a need for rapid provision of Bodies made of a material that solidifies at low temperatures. In particular is suitable dif device according to the invention for a sufficiently fast loading of an ultracentrifuge with Frozen hydrogen bodies, especially Dj, for fusion machines.

35 Here are 3 sheets of drawings

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Claims (1)

Patent claims: 1. Device for producing and dispensing a body from a solidified by cooling Material, e.g. B. hydrogen, with - A freezing cryostat (Ti) which contains a space (39) for solidifying the material and an extrusion nozzle (12) from which the body emerges, and - A receiving device (T2 ) arranged after the extrusion nozzle (12) which contains a channel (76) provided with a cooling device (64) for receiving the body and an outlet opening (78) for exiting the body,