EP3495711A1 - Transport container with coolable, thermal shield - Google Patents

Abstract

A transport container (1) for helium (He), with an inner container (6) for receiving the helium (He), a coolant container (14) for receiving a cryogenic fluid (N2), an outer container (2), in which the inner container ( 6) and the coolant container (14) are received, a thermal shield (21) in which the inner container (6) is accommodated and with the aid of the cryogenic fluid (N2) is actively cooled, wherein the thermal shield (21) at least one Cooling line (26) which is in fluid communication with the coolant container (14) and in which for the active cooling of the thermal shield (21) the cryogenic fluid (N2) is receivable, and at least one return line (34, 35), with the aid thereof the at least one cooling line (26) is in fluid communication with the coolant reservoir (14) for returning the cryogenic fluid (N2) to the coolant reservoir (14).

Description

The invention relates to a transport container for helium.

Helium is extracted together with natural gas. For economic reasons, transport of large quantities of helium is meaningful only in liquid or supercritical form, that is, at a temperature of about 4.2 to 6 K and under a pressure of 1 to 6 bar. To transport the liquid or supercritical helium transport containers are used, which are to avoid too rapid pressure increase of helium, consuming thermal insulation. Such transport containers can be cooled, for example, with the aid of liquid nitrogen. Here, a cooled with the liquid nitrogen thermal shield is provided. The thermal shield shields an inner container of the transport container. In the inner container, the liquid or cryogenic helium is added. The holding time for the liquid or cryogenic helium is in such transport containers 35 to 40 days, that is, after this time, the pressure in the inner container has risen to the maximum value of 6 bar. The supply of liquid nitrogen is sufficient for about 35 days.

Against this background, the object of the present invention is to provide an improved transport container available.

Accordingly, a transport container for helium is proposed. The transport container comprises an inner container for receiving the helium, a coolant container for receiving a cryogenic fluid, an outer container in which the inner container and the coolant container are accommodated, a thermal shield in which the inner container is accommodated and which can be actively cooled with the aid of the cryogenic fluid wherein the thermal shield has at least one cooling conduit in fluid communication with the coolant reservoir and in which the cryogenic fluid is receivable for actively cooling the thermal shield, and at least one return conduit with which the at least one cooling conduit is in fluid communication with the coolant reservoir is to supply the cryogenic fluid back to the coolant tank.

Characterized in that the return line is provided, the cryogenic fluid used for cooling from the cooling line is returned to the coolant tank. In particular, a liquid phase of the cryogenic fluid, which is entrained from the cooling line of the thermal shield due to bubble formation in the cooling line in the return line, and a vaporized phase of the cryogenic fluid can be returned to the coolant reservoir by means of the return line. By entraining the liquid phase, it can be ensured that the cryogenic fluid always remains in or is present in this up to a highest point of the cooling line. Non-evaporated cryogenic fluid is recirculated to the coolant tank in one circulation, in particular in a natural circulation, that is, in an automatic circulation. The gaseous phase is also returned to the coolant tank in this circulation.

On the use of a phase separator, which usually separates the gaseous phase of the cryogenic fluid from the liquid phase of the cryogenic fluid, this can be completely dispensed with. This reduces the cost of manufacturing and servicing the shipping container. Such a phase separator comprises moving parts and therefore has a limited life. Likewise, the incidence of heat on a comprehensive refrigeration system cooling system by a phase separator is not insignificant. This incidence of heat is eliminated by dispensing with the phase separator. Such a phase separator can also be damaged as outside of the transport container provided attachment during handling of the transport container. This danger is no longer due to the omission of the phase separator. The transport container is thus phase-separator-free or phase-separatorless.

The aforementioned natural circulation works preferably without or at least with a slight overpressure. Therefore, the pressure in the coolant tank can be lowered from 1.3 bara to 1.1 bara. This reduction in pressure leads to a lowering of the boiling temperature of the cryogenic fluid, in this case, for example, nitrogen, by 1.5 K. The heat input to the helium is thereby reduced by about 5%, so that the helium hold time compared to known transport containers by about three days increases.

The inner container may also be referred to as a helium container or as an inner tank. The transport container may also be referred to as a helium transport container. The helium can be referred to as liquid or cryogenic helium. The helium is in particular also a cryogenic fluid. The transport container is in particular adapted to transport the helium in cryogenic or liquid or in supercritical form. In thermodynamics, the critical point is a thermodynamic state of a substance characterized by equalizing the densities of liquid phase and gas phase. The differences between the two states of aggregation cease to exist at this point. In a phase diagram, the critical point represents the upper end of the vapor pressure curve.

The helium is filled in liquid or cryogenic form in the inner container. In the inner container then forms a liquid zone with liquid helium and a gas zone with gaseous helium. The helium therefore has two phases with different states of aggregation, namely liquid and gaseous, after being filled into the inner container. That is, in the inner container there is a phase boundary between the liquid helium and the gaseous helium. After a certain time, that is, when the pressure in the inner container rises, the helium in the inner container becomes single-phase. The phase boundary then no longer exists and the helium is supercritical.

The cryogenic fluid or cryogen is preferably liquid nitrogen. The cryogenic fluid may also be referred to as a coolant. The cryogenic fluid may alternatively be, for example, liquid hydrogen or liquid oxygen. By virtue of the fact that the thermal shield is actively coolable or actively cooled, it is to be understood that the cryogenic fluid at least partially flows through or flows around the thermal shield in order to cool it. In this case, the cryogenic fluid is boiling, and thus there is the gaseous phase and the liquid phase of the cryogenic fluid. In the cooling line, therefore, the cryogenic fluid can be accommodated both in its gaseous and in its liquid phase. Likewise, the cryogenic fluid may be received in the return line in its liquid phase and / or in its gaseous phase or be conveyed back to the coolant tank. In the return line, the liquid phase of the cryogenic fluid may at least partially vaporize. Unevaporated fractions of liquid phase of the cryogenic fluid fall back into the coolant tank. The liquid phase is promoted in particular by means of the gaseous phase of the cryogenic fluid. On a pump with moving components can be omitted. During operation of the transport container or of the thermal shield, during the evaporation of the cryogenic fluid, the liquid phase of the cryogenic fluid from the coolant container flows into the cooling line, so that the cooling line is always filled with the liquid phase over its entire length. The coolant tank, the cooling line and the return line thus form a cooling system. The cooling system is a closed system in which a circulation of the cryogenic fluid is possible.

In particular, the thermal shield is only actively cooled during operation of the transport container, that is, when the inner container is filled with helium. When the cryogenic fluid is exhausted, the thermal shield may also be uncooled. As previously mentioned, with active cooling of the thermal shield, the cryogenic fluid in the cooling line, but also in the return line, may evaporate. The thermal shield thus has a temperature which corresponds approximately or exactly to the boiling point of the cryogenic fluid. The boiling point of the cryogenic fluid is preferably higher than the boiling point of the liquid helium. The thermal shield is arranged in particular within the outer container. Preferably, the coolant reservoir is disposed outside of the thermal shield. Preferably, the cooling line and the return line are two separate components. That is, the cooling line does not correspond to the return line.

Preferably, the inner container has on the outside a temperature which corresponds approximately or exactly to the temperature of the helium stored in the inner container. The temperature of the helium is, depending on whether the helium is in liquid or supercritical form, 4.2 to 6 K. Preferably, a cover portion of the thermal shield completes a base portion of the same in each case from the front side completely. The base portion of the thermal shield may have a circular or approximately circular cross-section. The outer container, the inner container, the coolant container and the thermal shield can be constructed rotationally symmetrical to a common center or axis of symmetry. The inner container and the outer container are preferably made of stainless steel. The inner container preferably has a tubular base portion which is closed on both sides with curved lid portions.

The inner container is fluid-tight. The outer container preferably also has a tubular base portion, which is closed on both sides of the lid portions on the front side. The base portion of the inner container and / or the base portion of the outer container may have a circular or an approximately circular cross-section. The thermal shield is preferably made of a high purity aluminum material. The thermal shield is preferably not fluid-tight. That is, the thermal shield may have apertures or holes.

According to one embodiment, the at least one cooling line is in fluid communication with a liquid zone of the coolant tank, and the at least one return line is in fluid communication with a gas zone of the coolant tank.

With respect to a direction of gravity, the gas zone is located above the liquid zone. Between the gas zone and the liquid zone, a phase boundary is arranged. When the cryogenic fluid is introduced into the coolant reservoir, it at least partially evaporates, and the gas zone arranged above the fluid zone is formed. The cooling line thus opens into the liquid zone, and the return line opens into the gas zone.

According to a further embodiment, the at least one return line opens into the coolant container with respect to a direction of gravity above the at least one cooling line.

The return line is in particular connected directly to the coolant tank. The cooling line can be connected via a connecting line with the coolant tank. Alternatively, the cooling line can also be connected directly to the coolant tank. The cooling duct may have two vertical sections extending in the direction of gravity, which are interconnected by means of sections inclined relative to a horizontal plane. The cooling line may further comprise a distributor, in which the aforementioned connection line opens and which is connected by means of the connecting line with the coolant container. The distributor represents a lowest point of the cooling line. From the distributor then lead away a vertical and an oblique section of the cooling line. The vertical and the inclined sections of the cooling line reunite at a collector. The Collector represents a highest point of the cooling line. The return line is connected to the collector.

According to another embodiment, a lowest point of the at least one cooling line is in fluid communication with the coolant reservoir.

The lowest point of the cooling line may be the aforementioned manifold, which is in fluid communication with the coolant reservoir by means of the connecting line. The lowest point can also be referred to as a distributor or the distributor can be referred to as the lowest point of the cooling line.

According to a further embodiment, a highest point of the at least one cooling line is in fluid communication with the coolant container by means of the at least one return line.

The highest point of the cooling line is the aforementioned collector. The return line connects the collector to the coolant tank. The highest point can also be referred to as a collector or the collector can also be referred to as the highest point of the cooling line.

According to a further embodiment, an inner diameter of the at least one return line is greater than an inner diameter of the at least one cooling line.

This reliably prevents the cryogenic fluid from accumulating in the return line. Rather, in the cryogenic fluid forming gas bubbles, the liquid phase of the cryogenic fluid from the cooling line can tear into the return line. For example, the inner diameter of the return line is 10%, 20%, 30% or 40% larger than the inner diameter of the cooling line.

According to a further embodiment, the inner diameter of the at least one cooling line is greater than 10 millimeters.

For example, the inner diameter of the cooling line 12, 13, 14 or more millimeters.

According to a further embodiment, the at least one return line is inclined at an angle of inclination in the direction of the coolant container.

That is, the return line drops in the direction of the coolant tank. This ensures that the liquid phase of the cryogenic fluid flows back into the coolant tank. The inclination angle is defined as an inclination angle of the return line relative to a horizontal or to the symmetry axis of the transport container. The horizontal is positioned parallel to the symmetry axis.

According to a further embodiment, the at least one return line is connected to the thermal shield and arranged between the thermal shield and the outer container.

Preferably, the return line extends with respect to the direction of gravity at an upper portion of the thermal shield. The return line may be thermally and / or mechanically coupled to the thermal shield. For example, the return line can be glued or clamped to the thermal shield. The return line can also be arranged inside the thermal shield, instead of outside the thermal shield.

According to a further embodiment, during operation of the transport container, the cryogenic fluid boils for active cooling of the thermal shield in the at least one cooling line, such that gas bubbles of a gaseous phase of the cryogenic fluid which are formed in the at least one cooling line introduce a liquid phase of the cryogenic fluid into the at least one return line to supply the gaseous phase of the cryogenic fluid and / or the liquid phase of the cryogenic fluid back to the coolant reservoir.

The gas bubbles entrain the liquid phase of the cryogenic fluid from the cooling line into the return line. However, this results in no continuous, but a discontinuous promotion of the liquid phase of the cryogenic fluid. The cooling line and the return line thus form a pumping device in the form of a bubble pump or mammoth pump, which is adapted to the cryogenic fluid from the Coolant tank through the cooling line and from the cooling line via the return line to the coolant tank again.

According to a further embodiment, a first return line and a second return line are provided, which run parallel to one another.

The return lines can also run away from each other. The number of return lines is arbitrary. At least, however, a return line is provided.

According to a further embodiment, the coolant reservoir has a blow-off valve for blowing off a gaseous phase of the cryogenic fluid from the coolant reservoir.

As a result, the pressure in the coolant tank is regulated. The blown-off gaseous phase of the cryogenic fluid can be supplied to an actively coolable insulation element arranged between the thermal shield and the outer container. After passing through the gaseous phase of the cryogenic fluid through this insulating element, the gaseous phase is no longer cryogenic and can be discharged as a heated gaseous phase to the environment, without causing undesirable icing on the transport container.

According to a further embodiment, the inner container is completely surrounded by the thermal shield.

That is, the thermal shield completely envelops the inner container. The thermal shield is preferably not fluid-tight.

According to a further embodiment, the thermal shield has a cover section which is separate from the coolant reservoir and which is arranged between the inner reservoir and the coolant reservoir.

Preferably, the thermal shield on the tubular base portion which is closed on both sides of the lid portions. Between the inner container and the coolant container, one of the lid portions of the thermal shield is arranged. The lid portion of the thermal shield is in particular in one positioned between the inner container and the coolant tank space provided.

According to a further embodiment, the coolant reservoir is arranged outside the thermal shield.

Preferably, the coolant tank is positioned in an axial direction of the transport container adjacent to the thermal shield. Between the coolant tank and the thermal shield, a gap is provided. The coolant tank is preferably not part of the thermal shield.

Further possible implementations of the transport container also include not explicitly mentioned combinations of features or embodiments described above or below with regard to the exemplary embodiments. The expert will also add individual aspects as improvements or additions to the respective basic shape of the transport container.

• Fig. 1 zeigt eine schematische Ansicht einer Ausführungsform eines Transportbehälters;
• Fig. 2 zeigt eine weitere schematische Ansicht des Transportbehälters gemäß Fig. 1; und
• Fig. 3 zeigt eine schematische Schnittansicht des Transportbehälters gemäß der Schnittlinie III-III der Fig. 2.

Further advantageous embodiments of the transport container are the subject of the dependent claims and the embodiments of the transport container described below. Furthermore, the transport container will be explained in more detail by means of preferred embodiments with reference to the attached figures.

• Fig. 1 shows a schematic view of an embodiment of a transport container;
• Fig. 2 shows a further schematic view of the transport container according to Fig. 1 ; and
• Fig. 3 shows a schematic sectional view of the transport container according to the section line III-III of Fig. 2 ,

In the figures, the same or functionally identical elements have been given the same reference numerals, unless stated otherwise. The Fig. 1 shows a highly simplified schematic view of an embodiment of a transport container 1 for liquid helium He. The Fig. 2 shows another strong simplified schematic view of the transport container 1, and the Fig. 3 shows a schematic sectional view of the transport container 1 according to the section line III-III of Fig. 2 , The following is on the Fig. 1 to 3 simultaneously referred to.

The transport container 1 can also be referred to as a helium transport container. The transport container 1 can also be used for other cryogenic fluids. Examples of cryogenic fluids, or cryogens for short, are the aforementioned liquid helium He (boiling point at 1 bara: 4.222 K = -268.929 ° C), liquid hydrogen H2 (boiling point at 1 bara: 20.268 K = -252.882 ° C), more liquid Nitrogen N2 (boiling point at 1 bara: 7.35 K = 195.80 ° C) or liquid oxygen 02 (boiling point at 1 bara: 9.18 K = 182.97 ° C).

The transport container 1 comprises an outer container 2. The outer container 2 is made of stainless steel, for example. The outer container 2 may have a length L2 of, for example, 10 meters. The outer container 2 comprises a tubular or cylindrical base portion 3 which is closed on both sides in each case by means of a cover section 4, 5, in particular by means of a first cover section 4 and a second cover section 5. The base portion 3 may have a circular or approximately circular geometry in cross section. The lid sections 4, 5 are curved. The cover sections 4, 5 are arched in opposite directions, so that both cover sections 4, 5 are curved outwardly with respect to the base section 3. The outer container 2 is fluid-tight, in particular gas-tight. The outer container 2 has a center or symmetry axis M1, to which the outer container 2 is constructed rotationally symmetrical.

The transport container 1 further comprises an inner container 6 for receiving the helium He. The inner container 6 is in the Fig. 2 Not shown. The inner container 6 is also made of stainless steel, for example. In the inner container 6, as long as the helium He is in the two-phase region, a gas zone 7 with vaporized helium He and a liquid zone 8 with liquid helium He can be provided. The inner container 6 is fluid-tight, in particular gas-tight, and may comprise a blow-off valve for controlled pressure reduction. The inner container 6, like the outer container 2, comprises a tubular or cylindrical base portion 9 which is closed on both sides at the front by cover sections 10, 11, in particular a first cover section 10 and a second cover section 11. The Base section 9 may have a circular or approximately circular geometry in cross section. The inner container 6 is, like the outer container 2, constructed rotationally symmetrical to the axis of symmetry M1. The inner container 6 is completely enclosed by the outer container 2. Between the outer container 2 and the inner container 6, an evacuated gap or gap 12 is provided.

The transport container 1 further comprises a cooling system 13 (FIG. Fig. 2 ) with a coolant tank 14. The intermediate space 12 is also provided between the coolant tank 14 and the outer tank 2. The gap 12 is evacuated, as previously mentioned. The intermediate space 12 envelops the inner container 6 and the coolant reservoir 14 completely.

In the coolant tank 14, a cryogenic fluid such as nitrogen N2 is accommodated. Hereinafter, the cryogenic fluid is referred to as nitrogen N2. The coolant container 14 comprises a tubular or cylindrical base portion 15, which may be constructed rotationally symmetrical to the axis of symmetry M1. The base portion 15 may have a circular or approximately circular geometry in cross section. The base section 15 is closed at the front by a cover section 16, 17, in particular by a first cover section 16 and a second cover section 17. The lid portions 16, 17 may be curved. In particular, the lid portions 16, 17 are curved in the same direction. The coolant reservoir 14 may also have a different structure. The coolant reservoir 14 is arranged outside of the inner container 6, but inside the outer container 2.

In the coolant tank 14, a gas zone 18 with vaporized or gaseous nitrogen GN2 and a liquid zone 19 with liquid nitrogen LN2 may be provided. Viewed in a direction of gravity g, the gas zone 18 is arranged above the liquid zone 19. The gaseous nitrogen GN2 may also be referred to as the gaseous phase of the nitrogen N2 or of the cryogenic fluid. The liquid nitrogen LN2 can also be referred to as the liquid phase of the nitrogen N2 or of the cryogenic fluid. Viewed in an axial direction A of the transport container 1, the coolant container 14 is arranged next to the inner container 6. The axial direction A is positioned parallel to or agrees with the axis of symmetry M1. The axial direction A may be oriented by the first lid portion 4 of the outer container 2 in the direction of the second lid portion 5 of the outer container 2. Between the inner container 6, in particular between the second lid portion 11 of the inner container 6, and the coolant container 14, in particular the first lid portion 16 of the coolant container 14, a gap or gap 20 is provided, which may be part of the gap 12. That is, the gap 20 is also evacuated.

The transport container 1 further comprises a thermal shield 21 associated with 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 cooled or actively cooled with the aid of nitrogen N2. Active cooling in the present case is to be understood as meaning that the nitrogen N2 for the purpose of cooling the thermal shield 21 is passed through it or passed along it. The thermal shield 21 is hereby cooled to a temperature which corresponds approximately to the boiling point of the nitrogen N2.

The thermal shield 21 comprises a cylinder-shaped or tubular base section 22, which is closed on both sides by a cover section 23, 24, in particular a first cover section 23 and a second cover section 24, which terminates this end face. Both the base portion 22 and the lid portions 23, 24 are actively cooled by means of the nitrogen N2. The base portion 22 may have a circular or approximately circular geometry in cross section. The thermal shield 21 is preferably also constructed rotationally symmetrical to the axis of symmetry M1.

Viewed in the axial direction A, the second cover section 24 of the thermal shield 21 is arranged between the inner container 6, in particular the second lid section 11 of the inner container 6, and the coolant container 14, in particular the first lid section 16 of the coolant container 14. The thermal shield 21, in particular the second cover portion 24 of the thermal shield 21, is a separate component from the coolant reservoir 14. That is, the thermal shield 21, particularly the second lid portion 24 of the thermal shield 21, is not part of the coolant tank 14. The gap 12 completely envelops the thermal shield 21.

The first cover portion 23 of the thermal shield 21 is facing away from the coolant tank 14. The first lid portion 23 of the thermal shield 21 is disposed between the first lid portion 4 of the outer container 2 and the first lid portion 10 of the inner container 6. The thermal shield 21 is self-supporting. That is, the thermal shield 21 rests neither on the inner container 6 nor on the outer container 2. For this purpose, a support ring may be provided on the thermal shield 21, which is suspended by means of support rods, in particular tension rods, on the outer container 2. Furthermore, the inner container 6 can be suspended on the support ring via further support rods, in particular tension rods. The heat input through the mechanical support rods is partially realized by the support ring. The support ring has pockets that allow the greatest possible thermal length of the support rods. The coolant reservoir 14 may include bushings for the mechanical support rods.

The thermal shield 21 is fluid-permeable. That is, a gap or gap 25 between the inner container 6 and the thermal shield 21 is in fluid communication with the gap 12. In this way, the gaps 12, 25 can be evacuated simultaneously. The intermediate space 25 envelops the inner container 6 completely. In the intermediate space 25 can, in the Fig. 1 to 3 not shown, be arranged isolation element. This isolation element may be or include a so-called MLI (Multilayer Insulation). In the thermal shield 21 holes, openings or the like may be provided to allow simultaneous evacuation of the spaces 12, 25. The thermal shield 21 is preferably made of a high purity aluminum material.

The second cover portion 24 of the thermal shield 21 completely shields the coolant reservoir 14 from the inner container 6. That is, as seen from the inner container 6 to the coolant tank 14, in particular, viewed in the axial direction A, the coolant tank 14 is completely covered or shielded by the second lid portion 24 of the thermal shield 21. In particular, the thermal shield 21 encloses the inner container 6 completely. That is, the inner container 6 is completely disposed within the thermal shield 21, the thermal shield 21, as previously mentioned, is not fluid-tight.

As the Fig. 2 1, in which the inner container 6 is not shown, furthermore, the thermal shield 21 for actively cooling the same comprises at least one cooling line 26. The cooling line 26 is assigned to the cooling system 13. Preferably, a plurality of such cooling lines 26, for example six such cooling lines 26, are provided. However, the number of cooling lines 26 is arbitrary. The cooling line 26 may comprise two perpendicular sections 27, 28 extending in the direction of gravity g and two inclined sections 29, 30. The vertical sections 27, 28 may be provided on the lid sections 23, 24 and / or on the base section 22 of the thermal shield 21. The oblique sections 29, 30 may also be provided on the lid sections 23, 24 and / or on the base section 22. The portion 27 is in fluid communication with the portion 29 and the portion 30 is in fluid communication with the portion 28.

The cooling line 26 is connected to the thermal shield 21 both mechanically and thermally. For this purpose, the cooling line 26 can be materially connected to the thermal shield 21. In cohesive connections, the connection partners are held together by atomic or molecular forces. Cohesive connections are non-detachable compounds that can only be separated by destroying the connection means or the connection partners. Cohesive can be connected for example by gluing, soldering, welding or vulcanization. Preferably, the cooling line 26 or the cooling lines 26 are welded to the thermal shield 21, soldered or glued.

The cooling line 26 is in fluid communication with the coolant reservoir 14 by means of a connecting line 31, so that when the coolant reservoir 14 is filled, the nitrogen N 2 is forced from the coolant reservoir 14 into the cooling line 26. The connecting line 31 is part of the cooling line 26. The cooling line 26 may also be directly in communication with the coolant reservoir 14. The connection line 31 opens into a distributor 32, from which the section 27 and the section 30 of the cooling line 26 branch off. The distributor 32 forms a lowest point of the cooling line 26 with respect to the direction of gravity g. Therefore, the distributor 32 can also be referred to as the lowest point of the cooling line 26. This lowest point of the cooling line 26 is in fluid communication with the liquid zone 19 of the coolant tank 14 by means of the connecting line 31. In this case, the connection line 31 can open into a point of the coolant container 14 which is the lowest point with respect to the direction of gravity g. The Section 29 and the section 28 of the cooling line 26 meet at a collector 33, which forms a highest point of the cooling line 26 with respect to the direction of gravity g. Therefore, collector 33 may also be referred to as the highest point of the cooling line 26.

As mentioned above, the cooling pipes 26 are provided both on the base portion 22 and on the lid portions 23, 24 of the thermal shield 21. Alternatively, the cover sections 23, 24 are integral with one another, in particular materially bonded, to the base section 22. For example, the lid portions 23, 24 are welded to the base portion 22. As a result of the fact that the cover sections 23, 24 are connected to the base section 22 in a material-integral manner, that is to say in a material-locking manner, the cooling of the cover sections 23, 24 can also take place by heat conduction.

The cooling line 26 and in particular the inclined sections 29, 30 of the cooling line 26 have a pitch relative to a horizontal H1, which is arranged perpendicular to the direction of gravity g and parallel to the axis of symmetry M1. In particular, the inclined portions 29, 30 are inclined in the direction of the coolant tank 14. The sections 29, 30 with the horizontal H preferably include an angle of inclination α greater than 3 °. The inclination angle α can be 3 ° to 15 ° or even more. In particular, the inclination angle α can also be exactly 3 °. The inclination angle α can also be referred to as the first inclination angle. In particular, the sections 29, 30 have a positive gradient in the direction of the collector 33, so that gas bubbles produced during the boiling of the nitrogen N 2 in the cooling line 26 ascend to the collector 33. To the collector 33, a phase separator arranged outside the outer container 2 can be connected, which is set up to separate the gaseous nitrogen GN2 from the liquid nitrogen LN2 and to blow off the gaseous nitrogen GN2 into the environment. In the present case, however, dispensed with such a phase separator.

In the space 12, a in the Fig. 1 to 3 not shown isolation element may be arranged, which fills the gap 12. This insulating element is provided on the outside of the thermal shield 21 and can fill the gap 12. The insulation element preferably completely fills the gap 12 in the region of the inner container 6, so that there the insulation element thermal shield 21 on the outside and the outer container 2 inside contacted. The insulating member encloses the thermal shield 21 except for the second lid portion 24 thereof, that is, enclosing the first lid portion 23 and the base portion 22. Further, the cylindrical base portion 15 and the second lid portion 17 of the coolant tank 14 are enclosed by the insulating member. The isolation element is preferably also a so-called MLI or may comprise an MLI. The insulation element, like the thermal shield 21, can be actively cooled. The active cooling takes place with the aid of the cryogenic nitrogen GN2. For active cooling of the insulation element, a further cooling line can be passed through it. The cooling line can be helical or helical.

Furthermore, the transport container 1 comprises at least one return line 34, 35 (FIG. Fig. 3 ). Preferably, a first return line 34 and a second return line 35 are provided. However, the number of return lines 34, 35 is arbitrary. With the help of the return lines 34, 35, the cooling line 26 and the cooling lines 26 in fluid communication with the coolant tank 14 to supply the nitrogen N2 after passing through the cooling line 26 and the cooling lines 26 again to the coolant tank 14. The return lines 34, 35 may be provided on the outside of the thermal shield 21. The return lines 34, 35 are at least mechanically connected to the thermal shield 21 and preferably arranged between the thermal shield 21 and the outer container 2. Alternatively, the return lines 34, 35 may also be thermally connected to the thermal shield 21.

The return lines 34, 35 are inclined in the direction of the coolant tank 14. In particular, the return lines 34, 35 are inclined at an inclination angle β relative to a horizontal H2. The horizontal H2 is arranged parallel to or coincides with the horizontal H1. The inclination angle β may also be referred to as the second inclination angle. The inclination angle β may be 4 °, for example. The inclination angle β may be 4 ° to 15 ° or even more. In particular, the inclination angle β can also be exactly 4 °. The return lines 34, 35 are preferably associated with the cooling system 13.

Unlike the cooling line 26 and the cooling lines 26, respectively, which are in fluid communication with the liquid zone 19 of the coolant tank 14, the return lines 34, 35 are in fluid communication with the gas zone 18 of the coolant tank. That is, with respect to the direction of gravity g, the cooling lines 34, 35 above the cooling line 26, in particular above the connection line 31 of the cooling line 26, open into the coolant container 14. The accumulator 33, which is the highest point of the cooling line 26, is in fluid communication with the coolant reservoir 14 by means of the return lines 34, 35. For this purpose, for example, be provided on both sides of the thermal shield 21, such a collector 33. The return lines 34, 35 preferably run parallel to one another. An inner diameter d34, d35 of the return lines 34, 35 is greater than an inner diameter d26 of the cooling line 26. In this case, the inner diameter d26 of the cooling line 26 is preferably greater than 10 millimeters. The inner diameter d26 may be 12 millimeters, for example.

The cooling system 13 further comprises a blow-off valve 36, with the aid of which the gaseous nitrogen GN2 can be blown out of the coolant reservoir 14 in a pressure-dependent manner. The blow-off valve 36 is adapted to blow off the gaseous nitrogen GN2 to the environment. Alternatively, the aforementioned actively cooled isolation member disposed between the outer container 2 and the thermal shield 21 may be connected to the blow-off valve 36. Blown cryogenic nitrogen gas GN2 is then passed through the isolation element to actively cool it. The thereby heated gaseous nitrogen GN2 can then be released after passing through the cooling line of the insulation element to the environment. Due to the fact that the gaseous nitrogen GN2 is no longer cryogenic when it exits the insulation element, but is heated, undesirable icing of the exit point can be prevented.

The operation of the transport container 1 will be explained below. Before filling the inner container 6 with helium He, the thermal shield 21 is first of all approximately at least approximately or completely up to the boiling point (1.3 bara, 7.95 K) of the liquid nitrogen LN2 with the aid of cryogenic, initially gaseous and later liquid nitrogen N2 cooled. The inner container 6 is not actively cooled. Upon cooling of the thermal shield 21, the vacuum residual gas still remaining in the interstices 12, 20, 25 on the thermal shield 21 frozen out. As a result, it can be prevented when filling the inner container 6 with the helium He that the vacuum residual gas on the outside of the inner container 6 freezes and thus contaminated. As soon as the thermal shield 21 and the coolant reservoir 14 are completely cooled and the coolant reservoir 14 is again completely filled with nitrogen N 2, the inner reservoir 6 is filled with the liquid helium He.

The transport container 1 can now be transported on a transport vehicle, such as a truck or a ship, for transporting the helium He. Here, the thermal shield 21 is continuously cooled by means of the liquid nitrogen LN2. In this case, the liquid nitrogen LN 2 boils in the cooling line 26 or in the cooling lines 26. Resulting gas bubbles are supplied as gaseous nitrogen GN 2 to the highest point of the cooling system 13, namely the collector 33. In this case, it is always ensured that the cooling line 26 or the cooling lines 26 are acted upon over their entire length with liquid nitrogen LN2 and thereby have a temperature approximately corresponding to the boiling point of the nitrogen N2.

The gas bubbles thereby entrain liquid nitrogen LN2 from the cooling line 26 or from the cooling lines 26 and thus convey it into the return lines 34, 35. The liquid nitrogen LN2 is entrained by the resulting gas bubbles up to a static height of about two meters. This results in no continuous, but a discontinuous promotion of the liquid nitrogen LN2. The liquid nitrogen LN2 is pumped like a gush or in a surge. The conveyed into the return lines 34, 35 liquid nitrogen LN2 and the gaseous nitrogen GN2 are supplied via the return lines 34, 35 back to the coolant tank 14. The liquid nitrogen LN2 partially vaporizes in the return lines 34, 35. Unevaporated portions of the liquid nitrogen LN2 fall back into the coolant tank 14. Because the return lines 34, 35 have a larger inner diameter d34, d35 than the cooling line 26, the entrained liquid nitrogen LN2 can be conveyed freely into the return lines 34, 35.

This results in a natural circulation of the nitrogen N2. That is, the nitrogen N2 is from the cooling line 26 and the cooling lines 26 and the Return lines 34, 35 promoted without a moving parts having pump in a circle. The liquid nitrogen LN2 is conveyed only with the help of the gaseous nitrogen GN2. The cooling line 26 or the cooling lines 26 and the return lines 34, 35 act as a so-called bubble pump or mammoth pump, which is suitable for conveying the liquid nitrogen LN2. This natural circulation described above works without or at least approximately without overpressure. Therefore, the pressure in the coolant tank 14 can be reduced from the commonly required 1.3 bara to 1.1 bara. This lowering of the pressure in the coolant tank 14 leads to a lowering of the boiling temperature of the liquid nitrogen LN2 by 1.5 K. The heat input to the helium He is thereby reduced by about 5%, so that the helium hold time compared to an arrangement without Such return lines 34, 35 increases significantly, namely by about three days.

In the transport container 1 can advantageously be dispensed with a phase separator for separating the liquid nitrogen LN2 of the gaseous nitrogen N2. Such a phase separator comprises movable components which are subject to wear. That is, the phase separator has a limited life. By dispensing with a phase separator thus reduces both the cost of manufacturing and maintenance of such a transport container 1. Furthermore, by dispensing with the phase separator, which is usually arranged on the outside of the outer container 2 as an additional component, even the same damage is excluded. The handling of the transport container 1 is simplified by this. Also, caused by the phase separator heat input into the cooling system 13 is not negligible. Also for this reason, the waiver of the phase separator is advantageous.

Since cryogenic nitrogen gas is released only at one point, namely at the blow-off valve 36, the implementation of the active cooling of the insulation element arranged between the thermal shield 21 and the outer container 2 is simpler, since only one cooling line has to be laid. In the event that such an actively cooled insulation element is provided, only heated gaseous nitrogen GN2 exits from the transport container 1, so that in addition to the drastically increased Holding time for the liquid nitrogen LIN2 also, as already mentioned, no unwanted icing on the transport container 1 may occur.

Although the present invention has been described with reference to embodiments, it is variously modifiable.

Used reference signs

1

transport container

2

outer container

3

base section

4

cover section

5

cover section

6

inner container

7

gas zone

8th

liquid zone

9

base section

10

cover section

11

cover section

12

gap

13

cooling system

14

Coolant tank

15

base section

16

cover section

17

cover section

18

gas zone

19

liquid zone

20

gap

21

thermal shield

22

base section

23

cover section

24

cover section

25

gap

26

cooling line

27

section

28

section

29

section

30

section

31

connecting cable

32

distributor

33

collector

34

Return line

35

Return line

36

blow-off valve

A

axially

d26

Inner diameter

d34

Inner diameter

d35

Inner diameter

G

The direction of gravity

GN2

nitrogen

H1

horizontal

H2

horizontal

He

helium

LN2

nitrogen

L2

length

M1

axis of symmetry

N2

nitrogen

α

tilt angle

β

tilt angle

Claims (15)

Transport container (1) for helium (He), with an inner container (6) for receiving the helium (He), a coolant container (14) for receiving a cryogenic fluid (N2), an outer container (2), in which the inner container (6 ) and the coolant container (14), a thermal shield (21) in which the inner container (6) is accommodated and which is actively cooled by means of the cryogenic fluid (N2), wherein the thermal shield (21) at least one cooling line (26) which is in fluid communication with the coolant reservoir (14) and in which the cryogenic fluid (N2) is receivable for actively cooling the thermal shield (21) and at least one return line (34, 35) with the aid of which at least one cooling line (26) is in fluid communication with the coolant reservoir (14) for returning the cryogenic fluid (N2) to the coolant reservoir (14). The transport container according to claim 1, wherein the at least one cooling line (26) is in fluid communication with a liquid zone (19) of the coolant tank (14), and wherein the at least one return line (34, 35) is connected to a gas zone (18) of the coolant tank (14). is in fluid communication. Transport container according to claim 1 or 2, wherein the at least one return line (34, 35) opens with respect to a direction of gravity (g) above the at least one cooling line (26) in the coolant container (14). Transport container according to one of claims 1-3, wherein a lowest point of the at least one cooling line (26) with the coolant container (14) is in fluid communication. Transport container according to one of claims 1 - 4, wherein a highest point of the at least one cooling line (26) by means of the at least one return line (34, 35) in fluid communication with the coolant container (14). Transport container according to one of claims 1-5, wherein an inner diameter (d34, d35) of the at least one return line (34, 35) is greater than an inner diameter (d26) of the at least one cooling line (26). Transport container according to claim 6, wherein the inner diameter (d26) of the at least one cooling line (26) is greater than 10 millimeters. Transport container according to one of claims 1-7, wherein the at least one return line (34, 35) at an inclination angle (β) in the direction of the coolant container (14) is inclined. Transport container according to one of claims 1-8, wherein the at least one return line (34, 35) connected to the thermal shield (21) and between the thermal shield (21) and the outer container (2) is arranged. Transport container according to one of claims 1 - 9, wherein the cryogenic fluid (N2) during operation of the transport container (1) for actively cooling the thermal shield (21) in the at least one cooling line (26) boils, so that in the at least one cooling line ( 26) gas bubbles of a gaseous phase (GN2) of the cryogenic fluid (N2) produce a liquid phase (LN2) of the cryogenic fluid (N2) into the at least one return line (34, 35) to deliver the gaseous phase (GN2) of the cryogenic fluid (N2) and / or the liquid phase (LN2) of the cryogenic fluid (N2) again to the coolant tank (14) to supply. Transport container according to one of claims 1 - 10, wherein a first return line (34) and a second return line (35) are provided which are parallel to each other. Transport container according to one of claims 1 - 11, wherein the coolant container (14) has a blow-off valve (36) for blowing off a gaseous phase (GN2) of the cryogenic fluid (N2) from the coolant container (14). Transport container according to one of claims 1 - 12, wherein the inner container (6) is completely surrounded by the thermal shield (21). The transport container according to claim 13, wherein the thermal shield (21) has a lid portion (24) separated from the refrigerant container (14), which is disposed between the inner container (6) and the refrigerant container (14). Transport container according to one of claims 1-14, wherein the coolant container (14) outside the thermal shield (21) is arranged.

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