Transport container

Abstract

The invention relates to a transport container (1) for helium (He), comprising an inner container (6) for receiving the helium (He), 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), the thermal shield (21) comprising a tubular base section (22) in which the inner container (6) is received, and a cover section (23, 24) that closes the base section (22) at the front and that is arranged between the inner container (6) and the coolant container (14), wherein an intermediate space (20) is provided between the inner container (6) and the coolant.

Claims

1. A transport container for helium comprising: an inner container for receiving the helium, a coolant container for receiving a cryogenic liquid, an outer container in which the inner container and the coolant container are accommodated, and a thermal shield which is actively coolable with aid of the cryogenic liquid, wherein the thermal shield has a tubular base portion in which the inner container is accommodated, and a cover portion which closes off the base portion at an end face and which is arranged between the inner container and the coolant container, wherein an intermediate space, in which the cover portion of the thermal shield is arranged, is provided between the inner container and the coolant container, wherein the thermal shield has at least one cooling line for actively cooling the thermal shield, in which line the cryogenic liquid is receivable, and at least a portion of the at least one cooling line has a gradient with respect to a horizontal, and said container further comprises a phase separator for separating a gaseous phase of the cryogenic liquid from a liquid phase of the cryogenic liquid, wherein the at least one cooling line is arranged such that said at least one portion of the at least one cooling line has a positive gradient in the direction of the phase separator.

2. The transport container as claimed in claim 1, wherein the thermal shield is arranged in an evacuated intermediate space provided between the inner container and the outer container.

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

4. The transport container as claimed in claim 1, wherein the thermal shield is not supported on either the inner container or the outer container.

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

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

7. The transport container as claimed in claim 1, wherein the coolant container is in fluid connection with the at least one cooling line such that the cryogenic liquid flows into the at least one cooling line from the coolant container if the cryogenic liquid in the at least one cooling line partially evaporates.

8. The transport container as claimed in claim 1, wherein the at least one cooling line is provided on the base portion and/or on the cover portion of the thermal shield.

9. The transport container as claimed in claim 1, wherein said container has comprising a multiplicity of cooling lines.

10. The transport container as claimed in claim 1, wherein the cover portion of the thermal shield shields the coolant container completely from the inner container.

11. The transport container as claimed in claim 1, wherein the coolant container is arranged next to the inner container in an axial direction of the inner container.

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

13. The transport container as claimed in claim 1, wherein the base portion is connected to the cover portion in an integrally bonded manner.

14. The transport container as claimed in claim 8, wherein the base portion is connected to the cover portion in an integrally bonded manner.

15. The transport container as claimed in claim 1, wherein the outer container comprises a cylindrical a base portion which is closed at each end face by a cover portion, and each cover portion of the outer container is outwardly curved with respect to the base portion thereof, and the inner container comprises a cylindrical a base portion which is closed at each end face by a cover portion.

16. The transport container as claimed in claim 1, wherein the at least cooling line comprises two vertical portions and two portions having a gradient with respect to a horizontal.

17. The transport container as claimed in claim 1, wherein the at least cooling line is in fluid connection with the coolant container via a first connection line and is in fluid connection with the phase separator via a second connection line.

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;

(3) FIG. 2 shows a further schematic sectional view of the transport container as per FIG. 1;

(4) FIG. 3 shows a further schematic sectional view of the transport container as per FIG. 1;

(5) FIG. 4 shows a schematic sectional view of one embodiment of a phase separator for the transport container as per FIG. 1;

(6) FIG. 5 shows the detail view V as per FIG. 4;

(7) FIG. 6 shows a schematic rear view of the phase separator as per FIG. 4; and

(8) FIG. 7 shows a schematic partially sectional view of the phase separator as per FIG. 4.

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

(10) FIG. 1 shows a highly simplified schematic sectional view of one embodiment of a transport container 1 for liquid helium He. FIGS. 2 and 3 show further schematic sectional views of the transport container 1. In the following text, reference is made to FIGS. 1 to 3 simultaneously.

(11) 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.).

(12) 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 l.sub.2 of for example 10 meters. 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.

(13) 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.

(14) 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 inner container 6 may also have an insulating element (not shown in FIGS. 1 to 3). The insulating element has, on the outside, a highly reflective copper layer, for example a copper foil or an aluminum foil with a vapor-deposited copper coating, and a multilayered insulating layer arranged between the inner container 6 and the copper layer. The insulating layer comprises multiple alternately arranged layers of perforated and embossed aluminum foil, as a reflector, and glass paper, as a spacer, between the aluminum foils. The insulating layer may comprise 10 layers. The layers of aluminum foil and glass paper are applied on the inner container 6 without any gaps, that is to say are pressed. The insulating layer is a so-called MLI. The inner container 6 and also the insulating element are, on the outside, approximately at a temperature corresponding to the boiling point of the helium He.

(15) The transport container 1 also comprises a cooling system 13 (FIGS. 2, 3) with a coolant container 14. A cryogenic liquid, such as for example liquid nitrogen N.sub.2, is accommodated 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.

(16) 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 6, 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.

(17) 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 is to 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 to a temperature which corresponds approximately to the boiling point of the nitrogen N.sub.2.

(18) 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. 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 via support rods, in particular tension rods. Also, the inner container 6 may be suspended from the carrying ring via further support rods, in particular tension 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.

(19) A further multilayered insulating layer, in particular 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. In contrast to the above-described insulating element of the inner container 6, in this case, layers of aluminum foil and glass paper, glass silk or glass mesh fabric of the insulating layer are introduced loosely into the intermediate space 12. Loosely means here that the layers of aluminum foil and of glass paper, glass silk or glass mesh fabric are not pressed, with the result that the embossing and perforation of the aluminum foil allows the insulating layer, and consequently the intermediate space 12, to be evacuated without any problem. Since, as a result, the thermal-mechanical contact between the reflector layers is minimized, the temperature gradient of the reflector layers is established more or less according to pure radiation exchange, whereby the heat transport is minimized.

(20) 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. The thermal shield 21 is arranged peripherally spaced apart from the copper layer of the insulating element of the inner container 6 and does not make contact with it. As a result, the heat input is mainly realized by radiation and is consequently reduced to the minimum physically possible. A gap width of a gap provided between the copper layer and the thermal shield 21 may be 10 mm. Consequently, heat can be transferred from the inner container 6 to the thermal shield 21 only by radiation and residual gas conduction.

(21) The first cover portion 23 of the thermal shield 21 shields the cooling 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.

(22) As is also shown in FIGS. 2 and 3, the thermal shield 21 comprises at least one cooling line 26 for actively cooling it. Preferably, multiple such cooling lines 26 are provided, for example six such cooling lines 26. The cooling line 26 may comprise two vertical portions 27, 28, extending in a direction of gravitational force g, and two sloping portions 29, 30. The vertical portions 27, 28 may be provided on the cover portions 23, 24 of the thermal shield 21.

(23) The cooling line 26 is in fluid connection with the coolant container 14 via a connection line 31 such that the liquid nitrogen N.sub.2 is forced from the coolant container 14 into the cooling line 26. The connection line 31 opens out into a distributor 32, from which the portion 27 and the portion 30 branch off. The portion 29 and the portion 28 meet at a manifold 33, from which a connection line 34 leads to a phase separator 35 arranged outside the outer container 2. The phase separator 35 is set up to separate gaseous nitrogen N.sub.2 from liquid nitrogen N.sub.2. It is possible via the phase separator 35 for the gaseous nitrogen N.sub.2 to be blown off from the cooling system 13.

(24) The cooling line 26 or the cooling lines 26 is/are provided both on the base portion 22 and on the cover portions 23, 24 of the thermal shield 21. Alternatively, the cover portions 23, 24 are connected to the base portion 22 in a materially bonded manner. For example, the cover portions 23, 24 are welded to the base portion 22. If the cover portions 23, 24 are connected to the base portion 22 in a materially bonded manner, that is to say in an integrally bonded manner, the cooling of the cover portions 23, 24 can be realized by heat conduction. The cooling line 26, and in particular the sloping portions 29, 30 of the cooling line 26, has/have a gradient with respect to a horizontal H, which is arranged perpendicular to the direction of gravitational force g. In particular, the portions 29, 30 include an angle of greater than 3 with the horizontal H. The angle may be 3 to 15 or even more. In particular, the angle may also be exactly 3. In particular, the portions 29, 30 have a positive gradient in the direction of the phase separator 35.

(25) One embodiment of the phase separator 35 is shown in FIGS. 4 to 7. The phase separator 35 comprises a housing 36 with a tubular base portion 37, which is closed at the end face at each of the two end faces by cover portions 38, 39. Accommodated in the housing 36 is an inner housing 40 with a tubular base portion 41, which is closed at each of the two end faces by cover portions 42, 43. An evacuated insulating space 44 is provided between the housing 36 and the inner housing 40. The insulating space 44 may, for example, be provided with an MLI or be filled with perlite or glass microbeads. A connection line 45, which is partially likewise vacuum-insulated, is in fluid connection with the connection line 34. The phase separator 35 also comprises a blow-off line 46, via which gaseous nitrogen N.sub.2 is discharged. The connection line 45 is in fluid connection with an interior space 47 provided in the inner housing 40. The connection line 45 is rotationally offset with respect to the blow-off line 46 by an angle . The angle may be 45 to 90.

(26) A float 48 is provided in the interior space 47. The float 48 comprises a float body 49, which is provided with a gas-tight metallic casing and has its interior filled by a plastic foam. The float body 49 is connected fixedly to a counterweight 51 via a shaft 50. A valve body 52 which is arranged in a linearly displaceable manner in a valve seat 53 is fastened to the shaft 50. The shaft 50 is mounted rotatably in the inner housing 40 at an axis of rotation 54. That is to say, when the liquid level of the liquid nitrogen N.sub.2 in the interior space 47 falls, the float body 49 falls, whereby the shaft 50 rotates about the axis of rotation 54, whereby in turn the valve body 52 is lifted off from the valve seat 53 in order to blow off the gaseous nitrogen N.sub.2 via the blow-off line 46. The phase separator 35 ensures that only evaporated, cryogenic nitrogen N.sub.2 is delivered to the surroundings. The phase separator 35 is in particular a cryogenic valve regulated by the float 48. The special feature of the phase separator 35 is the counterweight 51 of the horizontally mounted float body 49, which counterweight prevents the valve body 52 from being lifted off from the valve seat 53 unintentionally in the event of accelerations.

(27) The phase separator 35 also comprises a valve 55 for generating a vacuum in the insulating space 44. An impact sheet 56, which is intended to reduce sloshing movement of the liquid nitrogen N.sub.2, may be arranged in the inner housing 40.

(28) Also, as is shown in FIGS. 2 and 3, a blow-off valve 57 is arranged at the coolant container 14 in order to maintain the set positive pressure in the coolant container 14 by blowing off the gaseous nitrogen N.sub.2.

(29) The functioning 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 of the insulating element of the inner container 6. As soon as the thermal shield 21 and the coolant container 14 have cooled down completely and the coolant container 14 is again completely filled with nitrogen N.sub.2, the inner container 6 is filled with the liquid helium He.

(30) 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 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 26. Gas bubbles produced in the process are fed through the phase separator 35, which is arranged highest in the cooling system 13 with respect to the direction of gravitational force g. As a result, the liquid level in the interior space 47 of the phase separator 35 falls, whereby the float body 49 also falls and the shaft 50 rotates about the axis of rotation 54, whereby the valve body 52 is lifted off from the valve seat 53. In this way, the gaseous nitrogen N.sub.2 is blown off via the blow-off line 46. As soon as the gaseous nitrogen N.sub.2 has been removed from the cooling system 13, liquid nitrogen N.sub.2 flows into the phase separator 35, whereby the float body 49 floats up again and the valve body 52 is pressed onto the valve seat 53. Here, the opening and closing of the phase separator 35 is realized in the Hertz range.

(31) Due to the mass inertia of the counterweight 51, unintended acceleration of the float body 49 during transport, for example due to vibrations, as a result of which the valve body 52 could lift off from the valve seat 53, can be prevented. Consequently, undesired loss of nitrogen N.sub.2 can be prevented. The fact that the thermal shield 21 is also arranged between the coolant container 14 and the inner container 6 means that it can be reliably ensured that the inner container 6 is sufficiently cooled even when there is a falling filling level or liquid level of nitrogen N.sub.2 in the coolant container 14. 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 surrounded only by surfaces which are at a temperature corresponding to the boiling point (at 1.3 bara, 79.5 K) of nitrogen N.sub.2. In this way, there is only a small difference in temperature between the thermal shield 21 (79.5 K) and the inner container 6 (4.2-6 K). This allows the holding time for the liquid helium He to be lengthened significantly in comparison with known transport containers. Heat is in this case transferred from the inner container 6 to the thermal shield 21 only by radiation and residual gas conduction. 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.

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

REFERENCE SIGNS USED

(33) 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 Cooling line 27 Portion 28 Portion 29 Portion 30 Portion 31 Connection line 32 Distributor 33 Manifold 34 Connection conductor 35 Phase separator 36 Housing 37 Base portion 38 Cover portion 39 Cover portion 40 Inner housing 41 Base portion 42 Cover portion 43 Cover portion 44 Insulating space 45 Connection line 46 Blow-off line 47 Interior space 48 Float 49 Float body 50 Shaft 51 Counterweight 52 Valve body 53 Valve seat 54 Axis of rotation 55 Valve 56 Impact sheet 57 Blow-off valve A Axial direction g Direction of gravitational force H Horizontal He Helium H.sub.2 Hydrogen l.sub.2 Length M.sub.1 Center axis N.sub.2 Nitrogen O.sub.2 Oxygen Angle Angle