Transport container

Abstract

The invention relates to a transport container (1) for helium (He), comprising an inner container (6) for receiving the liquid (He), an insulation element (26) that is provided on the exterior of the inner container (6), a coolant container (14) for receiving a cryogenic liquid (N.sub.2), an outer container (2) in which the inner container (6) and the coolant container (14) are received, and a thermal shield (21) which can be actively cooled with the aid of the cryogenic liquid (N.sub.2) and in which the inner container (6) is received, wherein a peripheral gap (31) is provided between the insulation element (26) and the thermal shield (21), and said insulation element (26) comprises a copper layer (27) that faces the thermal shield (21).

Claims

1. A transport container for helium, comprising: an inner container for receiving helium, an insulation element, which is provided on the exterior of the inner container, a coolant container for receiving a cryogenic liquid, an outer container, in which the inner container and the coolant container are received, a thermal shield, which can be actively cooled with the aid of the cryogenic liquid and in which the inner container is received, and a multilayered insulating layer arranged between the thermal shield and the outer container, wherein a peripheral gap is provided between the insulation element and the thermal shield, and wherein the insulation element comprises a copper layer facing the thermal shield.

2. The transport container as claimed in claim 1, wherein the peripheral gap (31) has a gap width (b.sub.31) of 5 to 15 millimeters.

3. The transport container as claimed in claim 1, wherein the peripheral gap is evacuated.

4. The transport container as claimed in claim 1, wherein the insulation element comprises a multilayered insulating layer arranged between the inner container and the copper layer.

5. The transport container as claimed in claim 4, wherein the multilayered insulating layer arranged between the inner container and the copper layer comprises multiple alternately arranged layers of aluminum film and glass paper.

6. The transport container as claimed in claim 5, wherein the layers of aluminum film and glass paper are applied to the inner container without any gaps.

7. The transport container as claimed in claim 1, wherein the copper layer is a copper film.

8. The transport container as claimed in claim 1, wherein the multilayered insulating layer arranged between the thermal shield and the outer container comprises multiple alternately arranged layers of aluminum film and glass silk, glass mesh fabric or glass paper.

9. The transport container as claimed in claim 8, wherein the layers of aluminum film and glass silk, glass mesh fabric or glass paper are applied to the thermal shield with gaps.

10. The transport container as claimed in claim 1, wherein the outer container is evacuated.

11. The transport container as claimed in claim 1, wherein the thermal shield completely encloses the inner container.

12. The transport container as claimed in claim 1, wherein the thermal shield has a base portion and two cover portions, which close off the base portion at both end faces.

13. The transport container as claimed in claim 1, wherein the thermal shield is fluid-permeable.

14. A transport container for helium, comprising: an inner container for receiving helium, an insulation element, which is provided on the exterior of the inner container, a coolant container for receiving a cryogenic liquid, an outer container, in which the inner container and the coolant container are received, and a thermal shield, which can be actively cooled with the aid of the cryogenic liquid and in which the inner container is received, wherein a peripheral gap is provided between the insulation element and the thermal shield, and wherein the insulation element comprises a copper layer facing the thermal shield, and wherein the thermal shield is fluid-permeable.

15. The transport container as claimed in claim 1, wherein the cryogenic liquid is liquid nitrogen, liquid hydrogen, or liquid oxygen.

16. The transport container as claimed in claim 1, wherein the copper layer has a thickness of at least 5 micrometers and less than 20 micrometers.

17. The transport container as claimed in claim 1, wherein the copper layer has a thickness in the range from 10 to 20 micrometers.

18. The transport container as claimed in claim 1, wherein the thermal shield is produced from an aluminum material.

19. The transport container as claimed in claim 1, wherein the outer container comprises a tubular or cylindrical base portion, which is closed at each end face by, respectively, a first cover portion and a second cover portion, the first and second cover portions are curved in opposite directions such that both cover portions are outwardly curved with respect to the base portion, the inner container comprises a tubular or cylindrical base portion, which is closed at each end face by, respectively, a first cover portion and a second cover portion, the first and second cover portions are curved in opposite directions such that both cover portions are outwardly curved with respect to the base portion, the coolant container comprises a tubular or cylindrical base portion, which is closed at each end face by, respectively, a first cover portion and a second cover portion, the first and second cover portions are curved in the same direction, and the thermal shield comprises a cylindrical or tubular base portion, which is closed at each end face by, respectively, a first cover portion and a second cover portion.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further advantageous configurations of the transport container form the subject matter of the dependent claims and of the exemplary embodiments of the transport container described below. The transport container will be explained in detail hereinafter on the basis of preferred embodiments with reference to the appended figures, in which:

(2) FIG. 1 shows a schematic sectional view of one embodiment of a transport container; and

(3) FIG. 2 shows the view of a detail II according to FIG. 1.

(4) In the figures, elements that are identical or have the same function have been provided with the same reference signs, unless stated otherwise.

(5) FIG. 1 shows a highly simplified schematic sectional view of one embodiment of a transport container 1 for liquid helium He. FIG. 2 shows the view of a detail II according to FIG. 1. In the following, reference is made to FIGS. 1 and 2 at the same time.

(6) The transport container 1 may also be referred to as a helium transport container. The transport container 1 may also be used for other cryogenic liquids. Examples of cryogenic liquids, or cryogens for short, are the previously mentioned liquid helium He (boiling point at 1 bara: 4.222 K=268.928 C.), liquid hydrogen H.sub.2 (boiling point at 1 bara: 20.268 K=252.882 C.), liquid nitrogen N.sub.2 (boiling point at 1 bara: 77.35 K=195.80 C.) or liquid oxygen O.sub.2 (boiling point at 1 bara: 90.18 K=182.97 C.).

(7) The transport container 1 comprises an outer container 2. The outer container 2 is produced for example from high-grade steel. The outer container 2 may have a length I.sub.2 of for example 10 m. The outer container 2 comprises a tubular or cylindrical base portion 3, which is closed at each of both the end faces with the aid of a cover portion 4, 5, in particular with the aid of a first cover portion 4 and a second cover portion 5. The base portion 3 may have a circular or approximately circular geometry in cross section. The cover portions 4, 5 are curved. The cover portions 4, 5 are curved in opposite directions such that both cover portions 4, 5 are outwardly curved with respect to the base portion 3. The outer container 2 is fluid-tight, in particular gas-tight. The outer container 2 has an axis of symmetry or center axis M.sub.1, in relation to which the outer container 2 is constructed rotationally symmetrically.

(8) The transport container 1 also comprises an inner container 6 for receiving the liquid helium He. The inner container 6 is likewise produced for example from high-grade steel. As long as the helium He is in the two-phase region, a gas zone 7 with evaporated helium He and a liquid zone 8 with liquid helium He may be provided in the inner container 6. The inner container 6 is fluid-tight, in particular gas-tight, and may comprise a blow-off valve for controlled pressure reduction. Like the outer container 2, the inner container 6 comprises a tubular or cylindrical base portion 9, which is closed at both end faces by cover portions 10, 11, in particular a first cover portion 10 and a second cover portion 11. The base portion 9 may have a circular or approximately circular geometry in cross section.

(9) Like the outer container 2, the inner container 6 is formed rotationally symmetrically in relation to the center axis M.sub.1. An intermediate space 12 provided between the inner container 6 and the outer container 2 is evacuated. The transport container 1 also comprises a cooling system 13 with a coolant container 14. A cryogenic liquid, such as for example liquid nitrogen N.sub.2, is received in the coolant container 14. The coolant container 14 comprises a tubular or cylindrical base portion 15, which may be constructed rotationally symmetrically in relation to the center axis M.sub.1. The base portion 15 may have a circular or approximately circular geometry in cross section. The base portion 15 is closed at each of the end faces by a cover portion 16, 17. The cover portions 16, 17 may be curved. In particular, the cover portions 16, 17 are curved in the same direction. The coolant container 14 may also have a different construction.

(10) A gas zone 18 with evaporated nitrogen N.sub.2 and a liquid zone 19 with liquid nitrogen N.sub.2 may be provided in the coolant container 14. The coolant container 14 is arranged next to the inner container 6 in an axial direction A of the inner container 6. An intermediate space 20, which may be part of the intermediate space 12, is provided between the inner container 6, in particular the cover portion 11 of the inner container, and the coolant container 14, in particular the cover portion 16 of the coolant container 14. That is to say, the intermediate space 20 is likewise evacuated.

(11) The transport container 1 also comprises a thermal shield 21 assigned to the cooling system 13. The thermal shield 21 is arranged in the evacuated intermediate space 12 provided between the inner container 6 and the outer container 2. The thermal shield 21 is actively coolable or actively cooled with the aid of the liquid nitrogen N.sub.2. Active cooling should be understood in the present case as meaning that, for cooling the thermal shield 21, the liquid nitrogen N.sub.2 is passed through, or passed along, said shield. Here, the thermal shield 21 is cooled down to a temperature which corresponds approximately to the boiling point of the nitrogen N.sub.2.

(12) The thermal shield 21 comprises a cylindrical or tubular base portion 22, which is closed on both sides by a cover portion 23, 24 closing it off at the end face. Both the base portion 22 and the cover portions 23, 24 are actively cooled with the aid of the nitrogen N.sub.2. The base portion 22 may have a circular or approximately circular geometry in cross section. The thermal shield 21 is preferably likewise constructed rotationally symmetrically in relation to the center axis M.sub.1.

(13) A first cover portion 23 of the thermal shield 21 is arranged between the inner container 6, in particular the cover portion 11 of the inner container 6, and the coolant container 14, in particular the cover portion 16 of the coolant container 14. A second cover portion 24 of the thermal shield 21 faces away from the coolant container 14. The thermal shield 21 is in this case self-supporting. That is to say that the thermal shield 21 is not supported on either the inner container 6 or the outer container 2. For this purpose, the thermal shield 21 may be provided with a carrying ring, which is suspended from the outer container 2 by support rods, in particular tension rods. Also, the inner container 6 may be suspended from the carrying ring via further support rods. The heat input through the mechanical support rods is partially realized by the carrying ring. The carrying ring has pockets, which allow the support rods to be of the greatest possible thermal length. The coolant container 14 has bushings for the mechanical support rods.

(14) The thermal shield 21 is fluid-permeable. That is to say that an intermediate space 25 between the inner container 6 and the thermal shield 21 is in fluid connection with the intermediate space 12. As a result, the intermediate spaces 12, 25 can be evacuated simultaneously. Bores, apertures or the like may be provided in the thermal shield 21, in order to allow evacuation of the intermediate spaces 12, 25. The thermal shield 21 is preferably produced from a high-purity aluminum material.

(15) The first cover portion 23 of the thermal shield 21 shields the coolant container 14 completely from the inner container 6. That is to say, when looking in the direction from the inner container 6 toward the coolant container 14, the coolant container 14 is completely covered by the first cover portion 23 of the thermal shield 21. In particular, the thermal shield 21 completely encloses the inner container 6. That is to say, the inner container 6 is arranged completely inside the thermal shield 21, wherein, as already mentioned above, the thermal shield 21 is not fluid-tight.

(16) The thermal shield 21 comprises at least one, but preferably multiple, cooling lines for actively cooling it. For example, the thermal shield 21 may have six cooling lines. The cooling line(s) is/are in fluid connection with the coolant container 14 such that the liquid nitrogen N.sub.2 can flow into the cooling line(s) from the coolant container 14. The cooling system 13 may also comprise a phase separator (not shown in FIG. 1), which is set up to separate gaseous nitrogen N.sub.2 from liquid nitrogen N.sub.2. It is possible via the phase separator for the gaseous nitrogen N.sub.2 to be blown off from the cooling system 13.

(17) The cooling line(s) is/are provided both on the base portion 22 and on the cover portions 23, 24 of the thermal shield 21. The cooling line or the cooling lines has/have a gradient with respect to a horizontal H, which is arranged perpendicular to a direction of gravitational force g. In particular, the cooling line or the cooling lines includes/include an angle of greater than 3 with the horizontal H.

(18) The inner container 6 also comprises an insulation element 26 that is shown as a detail in FIG. 2. The insulation element 26 completely encloses the inner container 6. That is to say that the insulation element 26 is provided both on the base portion 9 and on the cover portions 10, 11 of the inner container 6. The insulation element 26 is provided between the inner container 6 and the thermal shield 21. That is to say that the insulation element 26 is arranged in the intermediate space 25. The insulation element 26 has a highly reflective copper layer 27 on the outer side, that is to say facing the thermal shield 21. The copper layer 27 is metallically bright. That is to say that the copper layer 27 does not have a surface coating or oxide layer. The copper layer 27 may be for example a copper film or an aluminum film with a vapor-deposited copper coating.

(19) The actual thermal damping of the inner container 6 with respect to the temperature level of the liquid nitrogen N.sub.2 of the thermal shield 21 is provided by the copper layer 27. Preferably, the copper layer 27 is a smooth film of high-purity bright copper, which is drawn tightly and without creases around a multilayer insulating layer 28 arranged between the copper layer 27 and the inner container 6. The insulating layer 28 comprises multiple alternately arranged layers of perforated and embossed aluminum film 29, as a reflector, and glass paper 30, as a spacer and as damping in the event of a breakdown of the vacuum, between the aluminum films 29. The insulating layer 28 may comprise 10 layers. The layers of aluminum film 29 and glass paper 30 are applied on the inner container 6 without any gaps, that is to say are pressed. The insulating layer 28 may be what is known as an MLI. The inner container 6 and also the insulation element 26 are, on the outside, approximately at a temperature corresponding to the boiling point of the helium He. During the mounting of the insulating layer 28, it is ensured that the layers of aluminum film 29 and glass paper 30 have the greatest possible mechanical pressing, to achieve the effect that all of the layers of the insulating layer 28 are as isothermal as possible.

(20) Provided between the insulation element 26 and the thermal shield 21 is a gap 31, running completely around the inner container 6. The gap 31 is also provided between the insulation element 26 and the cover portions 23, 24 of the thermal shield 21. The gap 31 has a gap width b.sub.31. The gap width b.sub.31 is preferably 5 to 15 mm, but preferably 10 mm. The gap 31 is evacuated. In particular, the gap 31 is part of the intermediate space 25. The intermediate space 25 is in this case filled by the insulation element 26 apart from the gap 31.

(21) A further multilayered insulating layer 32, in particular likewise an MLI, may be arranged between the thermal shield 21 and the outer container 2, which insulating layer completely fills the intermediate space 12 and thus makes contact with the outside of the thermal shield 21 and the inside of the outer container 2. The insulating layer 32 is provided both between the respective base portions 3, 22 and between the cover portion 24 of the thermal shield 21 and the cover portion 4 of the outer container 2 and also between the cover portion 23 of the thermal shield 21 and the coolant container 14. The insulating layer 32 likewise comprises alternately arranged layers of aluminum film 33 and glass silk, glass mesh fabric or glass paper 34, which however, in contrast to the previously described insulation element 26 of the inner container 6, are in this case introduced loosely into the intermediate space 12. Loosely means here that the layers of aluminum film 33 and glass paper 34 are not pressed, with the result that the embossing and perforation of the aluminum film 33 allows the insulating layer 32, and consequently the intermediate space 12, to be evacuated without any control.

(22) With the aid of the gap 31, the thermal shield 21 is arranged peripherally spaced apart from the copper layer 27 of the insulation element 26 of the inner container 6 and is not in contact with it. As a result, the heat input by radiation is reduced to the minimum physically possible. Heat is only transferred from the surfaces of the inner container 6 to the thermal shield 21 by radiation and residual gas conduction.

(23) The functioning mode of the transport container 1 will be explained below. Before the filling of the inner container 6 with the liquid helium He, firstly the thermal shield 21 is cooled down with the aid of cryogenic, initially gaseous and later liquid, nitrogen N.sub.2 at least approximately or right up to the boiling point (at 1.3 bara: 79.5 K) of the liquid nitrogen N.sub.2. The inner container 6 is in this case not yet actively cooled. During the cooling down of the thermal shield 21, the residual vacuum gas still situated in the intermediate space 12 is frozen out on the thermal shield 21. In this way, when filling the inner container 6 with the liquid helium He, it can be prevented that the residual vacuum gas is frozen out on the outside of the inner container 6 and thereby contaminates the metallically bright surface of the copper layer 27 of the insulation element 26 of the inner container 6. As soon as the thermal shield 21 and the storage container 14 have cooled down completely and the coolant container 14 is again filled, the inner container 6 is filled with the liquid helium He.

(24) The transport container 1 may then be transferred onto a transporting vehicle, such as for example a truck or a ship, for the purpose of transporting the liquid helium He. This involves cooling the thermal shield 21 continuously with the aid of the liquid nitrogen N.sub.2. The liquid nitrogen N.sub.2 is thus used and boils in the cooling lines of the cooling system 13. Gas bubbles produced in the process are fed through the phase separator that is arranged highest in the cooling system 13 with respect to the direction of gravitational force g. With the aid of the phase separator, the gaseous nitrogen N.sub.2 situated in the cooling system 13 can be blown off, whereby the liquid nitrogen N.sub.2 from the coolant container 14 can flow in after it.

(25) Since the copper layer 27 does not have any mechanical contact with the thermal shield 21 because of the gap 31, heat can only be transferred from the surfaces of the inner container 6 to the thermal shield 21 by radiation and residual gas conduction. Since the copper layer has been drawn tightly onto the insulating layer 28, it has good mechanical contact with the insulating layer 28, and the copper layer 27 is likewise at a temperature that is close to the temperature of the helium He. Since the degree of emission or the emissivity of the copper layer 27 decreases with decreasing temperature, the heat transfer by radiation also decreases, with the result that the overall heat input to the inner container 6 can be suppressed to below 6 W over the holding time for the helium He. The degree of emission of a body indicates how much radiation it gives off in comparison with an ideal heat emitter, a black body.

(26) The fact that the inner container 6 is completely surrounded by the thermal shield 21 means that it is ensured that the inner container 6 is only surrounded by surfaces that are at a temperature corresponding to the boiling point (1.3 bara, 78.5 K) of nitrogen N.sub.2. In this way, there is only a small difference in temperature between the thermal shield 21 (78.5 K) and the inner container (4.2-6 K). This allows the holding time for the liquid helium He to be lengthened significantly in comparison with known transport containers. The transport container 1 has in particular a holding time for helium of at least 45 days, and the supply of liquid nitrogen N.sub.2 is sufficient for at least 40 days. The insulation element 26 has the function of an emergency insulation for the inner container 6 for the event of a breakdown of the vacuum.

(27) Although the present invention has been described using exemplary embodiments, it is modifiable in various ways.

REFERENCE SIGNS USED

(28) 1 Transport container 2 Outer container 3 Base portion 4 Cover portion 5 Cover portion 6 Inner container 7 Gas zone 8 Liquid zone 9 Base portion 10 Cover portion 11 Cover portion 12 Intermediate space 13 Cooling system 14 Coolant container 15 Base portion 16 Cover portion 17 Cover portion 18 Gas zone 19 Liquid zone 20 Intermediate space 21 Shield 22 Base portion 23 Cover portion 24 Cover portion 25 Intermediate space 26 insulation element 27 Copper layer 28 Insulating layer 29 Aluminum film 30 Glass paper 31 Gap 32 Insulating layer 33 Aluminum film 34 Glass paper A Axial direction b.sub.31 Gap width g Direction of gravitational force H Horizontal He Helium H.sub.2 Hydrogen I.sub.2 Length M.sub.1 Central axis N.sub.2 Nitrogen O.sub.2 Oxygen