EP3495711B1 - Transport container with coolable, thermal shield - Google Patents

Description

The invention relates to a transport container for helium.

Helium is extracted together with natural gas. For economic reasons, transporting large quantities of helium only makes sense 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. Transport containers are used to transport the liquid or supercritical helium, as in US47182439 and WO2017 / 190849 proposed that, in order to avoid a rapid rise in pressure of the helium, are thermally insulated in a complex manner. Such transport containers can be cooled using liquid nitrogen, for example. Here, a thermal shield cooled with the liquid nitrogen is provided. The thermal shield shields an inner container of the transport container. The liquid or cryogenic helium is accommodated in the inner container. The holding time for the liquid or cryogenic helium in such transport containers is 35 to 40 days, that is to say 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.

Accordingly, a transport container for helium is proposed. The transport container comprises an inner container for holding the helium, a coolant container for holding 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 using the cryogenic fluid , wherein the thermal shield has at least one cooling line which is in fluid communication with the coolant container and in which the cryogenic fluid can be received for actively cooling the thermal shield, and at least one return line, with the aid of which the at least one cooling line is in fluid communication with the coolant container is to feed the cryogenic fluid back to the coolant tank.

Because the return line is provided, the cryogenic fluid used for cooling is fed back from the cooling line to the coolant container. With the aid of the return line, in particular a liquid phase of the cryogenic fluid, which is entrained from the cooling line of the thermal shield due to the formation of bubbles in the cooling line into the return line, and an evaporated phase of the cryogenic fluid can be returned to the coolant container. The entrainment of the liquid phase can ensure that the cryogenic fluid is always in the cooling line up to the highest point or is present in the cooling line. Unevaporated cryogenic fluid is returned to the coolant tank in one cycle, in particular in a natural cycle, that is, in an automatic cycle. The gaseous phase is also returned to the coolant tank in this cycle.

The use of a phase separator, which usually separates the gaseous phase of the cryogenic fluid from the liquid phase of the cryogenic fluid, can thus be completely dispensed with. This reduces the cost of manufacturing and maintaining the shipping container. Such a phase separator comprises moving parts and therefore has a limited service life. Likewise, the incidence of heat on a cooling system comprising the cooling line through a phase separator is not insignificant. This loss of heat is eliminated by dispensing with the phase separator. Such a phase separator can also be damaged as an attachment provided on the outside of the transport container when handling the transport container. This risk also no longer exists due to the absence of the phase separator. The transport container is thus free of phase separators or without phase separators.

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

The inner container can also be called a helium container or an inner tank. The transport container can also be referred to as a helium transport container. The helium can be referred to as liquid or cryogenic helium. In particular, the helium is also a cryogenic fluid. The transport container is in particular set up to transport the helium in cryogenic or liquid or in supercritical form. In thermodynamics, the critical point is a thermodynamic state of a substance, which is characterized by matching the densities of the liquid phase and gas phase. The differences between the two aggregate states 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 into the inner container in liquid or cryogenic form. A liquid zone with liquid helium and a gas zone with gaseous helium then form in the inner container. After being filled into the inner container, the helium therefore has two phases with different aggregate states, namely liquid and gaseous. This means that there is a phase boundary between the liquid helium and the gaseous helium in the inner container. 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 can also be referred to as a coolant. The cryogenic fluid can alternatively also be liquid hydrogen or liquid oxygen, for example. The fact that the thermal shield can be actively cooled or actively cooled means that the cryogenic fluid flows through or around the thermal shield at least partially in order to cool it. The cryogenic fluid boils and the gaseous phase and the liquid phase of the cryogenic fluid are thus present. The cryogenic fluid can therefore be taken up in the cooling line both in its gaseous and in its liquid phase. Likewise, the cryogenic fluid in the return line can be taken up in its liquid phase and / or in its gaseous phase or can be conveyed back to the coolant container. The liquid phase of the cryogenic fluid can at least partially evaporate in the return line. Unevaporated portions of the liquid phase of the cryogenic fluid fall back into the coolant tank. The liquid phase is conveyed in particular with the help of the gaseous phase of the cryogenic fluid. There is no need for a pump with moving components. When the transport container or the thermal shield is in operation, when the cryogenic fluid evaporates, the liquid phase of the cryogenic fluid flows out of the coolant container 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 the cryogenic fluid can circulate.

In particular, the thermal shield is actively cooled only when the transport container is in operation, that is to say when the inner container is filled with helium. When the cryogenic fluid is used up, the thermal shield can also be uncooled. As previously mentioned, when the thermal shield is actively cooled, the cryogenic fluid in the cooling line, but also in the return line, can evaporate. As a result, the thermal shield has a temperature that approximately or exactly corresponds 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 in particular arranged inside the outer container. The coolant container is preferably arranged outside the thermal shield. The cooling line and the return line are preferably two separate components. This means that the cooling line does not correspond to the return line.

The inner container preferably has a temperature on the outside which approximately or exactly corresponds to the temperature of the helium stored in the inner container. The temperature of the helium, depending on whether the helium is in liquid or supercritical form, is 4.2 to 6 K. Preferably, a cover section of the thermal shield completely closes off a base section of the same at the end. The base portion of the thermal shield can 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 symmetrically to a common center or symmetry axis. The inner container and the outer container are preferably made of stainless steel. The inner container preferably has a tubular base section which is closed on both sides with curved cover sections.

The inner container is fluid-tight. The outer container preferably also has a tubular base section which is closed on both ends by cover sections. The base section of the inner container and / or the base section of the outer container can 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. This means that the thermal shield can have openings or holes.

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

With regard to a direction of gravity, the gas zone is arranged above the liquid zone. A phase boundary is arranged between the gas zone and the liquid zone. When the cryogenic fluid is filled into the coolant container, it evaporates at least partially, and the gas zone arranged above the liquid zone forms. 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 tank 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 to the coolant tank via a connecting line. Alternatively, the cooling line can also be connected directly to the coolant tank. The cooling line can have two vertical sections running in the direction of gravity, which are connected to one another by means of sections arranged obliquely with respect to a horizontal. The cooling line can furthermore have a distributor into which the aforementioned connection line opens and which is connected to the coolant tank with the aid of the connection line. The distributor represents a lowest point of the cooling line. A vertical and an inclined section of the cooling line then lead away from the distributor. The vertical and the oblique sections of the cooling line are combined again in one collector. Of the Collector represents the highest point of the cooling line. The return line is connected to the collector.

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

The lowest point of the cooling line can be the aforementioned distributor, which is in fluid communication with the coolant tank by means of the connecting line. The lowest point can also be called the distributor or the distributor can be called 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 tank by means of the at least one return line.

The highest point of the cooling line is the previously mentioned collector. The return line connects the collector to the coolant tank. The highest point can also be called the collector or the collector can also be called the highest point of the cooling line.

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

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

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

For example, the inside diameter of the cooling line is 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 towards the coolant tank. This ensures that the liquid phase of the cryogenic fluid flows back into the coolant container. The angle of inclination is defined as an angle of inclination of the return line relative to a horizontal or to the axis of symmetry of the transport container. The horizontal is positioned parallel to the axis of symmetry.

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

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

According to a further embodiment, the cryogenic fluid boils in the operation of the transport container for actively cooling the thermal shield in the at least one cooling line, so that gas bubbles of a gaseous phase of the cryogenic fluid arising in the at least one cooling line result in a liquid phase of the cryogenic fluid in the at least one return line promote to feed the gaseous phase of the cryogenic fluid and / or the liquid phase of the cryogenic fluid back to the coolant tank.

The gas bubbles tear the liquid phase of the cryogenic fluid from the cooling line into the return line. However, this does not result in continuous, but rather discontinuous, conveyance of the liquid phase of the cryogenic fluid. The cooling line and the return line thus form a pump device in the form of a bubble pump or mammoth pump, which is suitable for removing the cryogenic fluid from the Return the coolant tank to the coolant tank through the cooling line and from the cooling line via the return line.

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 one return line is provided.

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

This regulates the pressure in the coolant tank. 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 the gaseous phase of the cryogenic fluid has passed through this insulation element, the gaseous phase is no longer cryogenic and can be released into the environment as a heated gaseous phase without undesired icing of the transport container being able to occur.

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

This means that 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 container and is arranged between the inner container and the coolant container.

The thermal shield preferably has the tubular base section, which is closed on both sides by the cover sections. One of the lid sections of the thermal shield is arranged between the inner container and the coolant container. The lid portion of the thermal shield is particularly in one positioned between the inner container and the coolant tank space.

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

The coolant container is preferably positioned in an axial direction of the transport container next to the thermal shield. A space is provided between the coolant tank and the thermal shield. The coolant tank is preferably not part of the thermal shield.

Further possible implementations of the transport container also include combinations of features or embodiments described above or below with reference to the exemplary embodiments that are not explicitly mentioned. The specialist 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 subclaims and the exemplary embodiments of the transport container described below. Furthermore, the transport container is explained in more detail based on preferred embodiments with reference to the accompanying 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 section line III-III of Fig. 2 .

In the figures, elements that are the same or have the same function have been provided with the same reference symbols, 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 the 1 to 3 referred to at the same time.

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 can have a length L2 of, for example, 10 meters. The outer container 2 comprises a tubular or cylindrical base section 3, which is closed on both sides with a cover section 4, 5, in particular with a first cover section 4 and a second cover section 5. The base section 3 can have a circular or approximately circular geometry in cross section. The lid sections 4, 5 are curved. The cover sections 4, 5 are curved in opposite directions, so that both cover sections 4, 5 are curved outwards 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 symmetrically.

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. 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 can be provided in the inner container 6. The inner container 6 is fluid-tight, in particular gas-tight, and can comprise a blow-off valve for controlled pressure reduction. Like the outer container 2, the inner container 6 comprises a tubular or cylindrical base section 9, which is closed on both ends by cover sections 10, 11, in particular a first cover section 10 and a second cover section 11. Of the The base section 9 can have a circular or approximately circular geometry in cross section. The inner container 6, like the outer container 2, is constructed rotationally symmetrically to the axis of symmetry M1. The inner container 6 is completely enclosed by the outer container 2. An evacuated gap or space 12 is provided between the outer container 2 and the inner container 6.

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

A cryogenic fluid, such as nitrogen N2, is received in the coolant container 14. The cryogenic fluid is therefore referred to below as nitrogen N2. The coolant container 14 comprises a tubular or cylindrical base section 15, which can be constructed rotationally symmetrical to the axis of symmetry M1. The base section 15 can have a circular or approximately circular geometry in cross section. The base section 15 is closed on the end side by a cover section 16, 17, in particular by a first cover section 16 and a second cover section 17. The lid sections 16, 17 can be curved. In particular, the cover sections 16, 17 are curved in the same direction. The coolant tank 14 can also have a different structure. The coolant container 14 is arranged outside the inner container 6, but inside the outer container 2.

A gas zone 18 with evaporated or gaseous nitrogen GN2 and a liquid zone 19 with liquid nitrogen LN2 can be provided in the coolant container 14. When viewed in a direction of gravity g, the gas zone 18 is arranged above the liquid zone 19. The gaseous nitrogen GN2 can 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. When 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 coincides with the axis of symmetry M1. The axial direction A can be oriented from the first cover section 4 of the outer container 2 in the direction of the second cover section 5 of the outer container 2. Between the inner container 6, in particular between the second cover section 11 of the inner container 6, and the coolant container 14, in particular the first cover section 16 of the coolant container 14, a gap or space 20 is provided, which can be part of the space 12. That is, the space 20 is also evacuated.

The transport container 1 further 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 can be actively cooled or actively cooled using the nitrogen N2. In the present case, active cooling is understood to mean that the nitrogen N2 is passed through or guided along the thermal shield 21 for cooling the latter. The thermal shield 21 is cooled to a temperature which corresponds approximately to the boiling point of the nitrogen N2.

The thermal shield 21 comprises a cylindrical or tubular base section 22, which is closed on both sides by a cover section 23, 24 that closes the end face, in particular a first cover section 23 and a second cover section 24. Both the base section 22 and the cover sections 23, 24 are actively cooled with the aid of nitrogen N2. The base section 22 can have a circular or approximately circular geometry in cross section. The thermal shield 21 is preferably also constructed to be 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 cover section 11 of the inner container 6, and the coolant container 14, in particular the first cover section 16 of the coolant container 14. The thermal shield 21, in particular the second cover section 24 of the thermal shield 21, is a component separate from the coolant container 14. That is, the thermal shield 21, in particular the second cover section 24 of the thermal shield 21, is not part of the coolant container 14. The intermediate space 12 completely envelops the thermal shield 21.

The first cover section 23 of the thermal shield 21 faces away from the coolant container 14. The first cover section 23 of the thermal shield 21 is arranged between the first cover section 4 of the outer container 2 and the first cover section 10 of the inner container 6. The thermal shield 21 is self-supporting. That is, the thermal shield 21 is not supported on either the inner container 6 or the outer container 2. For this purpose, a support ring can be provided on the thermal shield 21, which is suspended from the outer container 2 via support rods, in particular tension rods. Furthermore, the inner container 6 can be suspended from the support ring via further support rods, in particular tension rods. The heat input from 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 tank 14 may include bushings for the mechanical support rods.

The thermal shield 21 is fluid permeable. This means that a gap or intermediate space 25 between the inner container 6 and the thermal shield 21 is in fluid communication with the intermediate space 12. As a result, the intermediate spaces 12, 25 can be evacuated at the same time. The intermediate space 25 completely envelops the inner container 6. In the space 25, one in the 1 to 3 Insulation element, not shown, may be arranged. This insulation element can be or comprise a so-called MLI (multilayer insulation). Bores, breakthroughs or the like can be provided in the thermal shield 21 in order to enable a simultaneous evacuation of the intermediate spaces 12, 25. The thermal shield 21 is preferably made of a high-purity aluminum material.

The second cover section 24 of the thermal shield 21 completely shields the coolant tank 14 from the inner tank 6. That is to say, when looking from the inner container 6 onto the coolant container 14, in particular when looking in the axial direction A, the coolant container 14 is completely covered or shielded by the second cover section 24 of the thermal shield 21. In particular, the thermal shield 21 completely encloses the inner container 6. This means that the inner container 6 is arranged entirely within the thermal shield 21, the thermal shield 21, as already mentioned, not being fluid-tight.

As the Fig. 2 , in which the inner container 6 is not shown, furthermore shows, 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. A plurality of such cooling lines 26, for example six such cooling lines 26, are preferably provided. However, the number of cooling lines 26 is arbitrary. The cooling line 26 can comprise two vertical sections 27, 28 running in the direction of gravity g and two inclined sections 29, 30. The vertical sections 27, 28 can be provided on the cover sections 23, 24 and / or on the base section 22 of the thermal shield 21. The inclined sections 29, 30 can also be provided on the cover sections 23, 24 and / or on the base section 22. Section 27 is in fluid communication with section 29 and section 30 is in fluid communication with section 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 integrally connected to the thermal shield 21. In the case of integral connections, the connection partners are held together by atomic or molecular forces. Integral connections are non-detachable connections 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 vulcanizing. The cooling line 26 or the cooling lines 26 are preferably welded, soldered or glued to the thermal shield 21.

The cooling line 26 is in fluid communication with the coolant tank 14 by means of a connecting line 31, so that when the coolant tank 14 is filled, the nitrogen N2 is pressed into the cooling line 26 by the coolant tank 14. The connecting line 31 is part of the cooling line 26. The cooling line 26 can also be connected directly to the coolant tank 14. The connecting 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. The distributor 32 can therefore 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 container 14 with the aid of the connecting line 31. The connecting line 31 can open into a point of the coolant container 14 that is lowest with respect to the direction of gravity g. Of the Section 29 and 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. Collector 33 can therefore also be referred to as the highest point of cooling line 26.

As previously mentioned, the cooling lines 26 are provided on both the base portion 22 and the lid portions 23, 24 of the thermal shield 21. Alternatively, the cover sections 23, 24 are connected to the base section 22 in one piece, in particular materially. For example, the cover sections 23, 24 are welded to the base section 22. Because the cover sections 23, 24 are connected to the base section 22 in one piece, that is to say integrally, the cover sections 23, 24 can also be cooled by heat conduction.

The cooling line 26 and in particular the oblique sections 29, 30 of the cooling line 26 have an incline with respect 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 sections 29, 30 are inclined in the direction of the coolant container 14. The sections 29, 30 preferably include an inclination angle α of greater than 3 ° with the horizontal H. The angle of inclination α can be 3 ° to 15 ° or more. In particular, the angle of inclination α can also be exactly 3 °. The angle of inclination α can also be referred to as the first angle of inclination. In particular, the sections 29, 30 have a positive slope in the direction of the collector 33, so that gas bubbles formed in the cooling line 26 during the boiling of the nitrogen N2 rise to the collector 33. A phase separator arranged outside the outer container 2 can be connected to the collector 33 and 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. However, such a phase separator is dispensed with in the present case.

In the space 12 can in the 1 to 3 Insulation element, not shown, may be arranged, which fills the intermediate space 12. This insulation element is provided on the outside of the thermal shield 21 and can fill the intermediate space 12. The insulation element preferably completely fills the space 12 in the area of the inner container 6, so that the insulation element there thermal shield 21 contacted on the outside and the outer container 2 on the inside. The insulation element encloses the thermal shield 21 except for its second cover section 24, that is to say it surrounds the first cover section 23 and the base section 22. Furthermore, the cylindrical base section 15 and the second cover section 17 of the coolant container 14 are enclosed by the insulation element. The insulation element is preferably also a so-called MLI or can comprise an MLI. Like the thermal shield 21, the insulation element can be actively cooled. The active cooling takes place with the help of the extremely cold gaseous nitrogen GN2. For the 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. 3 ). A first return line 34 and a second return line 35 are preferably provided. However, the number of return lines 34, 35 is arbitrary. With the aid of the return lines 34, 35, the cooling line 26 or the cooling lines 26 are in fluid communication with the coolant tank 14 in order to feed the nitrogen N2 back to the coolant tank 14 after passing through the cooling line 26 or the cooling lines 26. The return lines 34, 35 can be provided on the outside on the thermal shield 21. The return lines 34, 35 are at least mechanically connected to the thermal shield 21 and are preferably arranged between the thermal shield 21 and the outer container 2. Alternatively, the return lines 34, 35 can 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 the horizontal H1 or corresponds to it. The angle of inclination β can also be referred to as the second angle of inclination. The angle of inclination β can be 4 °, for example. The angle of inclination β can be 4 ° to 15 ° or more. In particular, the angle of inclination β can also be exactly 4 °. The return lines 34, 35 are preferably assigned to the cooling system 13.

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

The cooling system 13 further includes a blow-off valve 36, by means of which the gaseous nitrogen GN2 can be blown out of the coolant tank 14 in a pressure-dependent manner. The blow-off valve 36 is suitable for blowing off the gaseous nitrogen GN2 to the environment. Alternatively, the aforementioned actively cooled insulation element, which is arranged between the outer container 2 and the thermal shield 21, can be connected to the blow-off valve 36. Blown off cryogenic gaseous nitrogen GN2 is then passed through the insulation element in order to actively cool it. The heated gaseous nitrogen GN2 can then be released into the environment after passing through the cooling line of the insulation element. The fact that the gaseous nitrogen GN2 is then no longer cryogenic when it emerges from the insulation element, but rather warms up, preventing undesired icing of the exit point.

The mode of operation of the transport container 1 is explained below. Before the inner container 6 is filled with helium He, the thermal shield 21 is at least approximately or completely at least to the boiling point (1.3 bara, 7.95 K) of the liquid nitrogen LN2 with the help of cryogenic, initially gaseous and later liquid nitrogen N2 cooled down. The inner container 6 is not yet actively cooled. When the thermal shield 21 cools, the vacuum residual gas still located in the spaces 12, 20, 25 becomes on the thermal shield 21 frozen out. When the inner container 6 is filled with the helium He, this can prevent the vacuum residual gas from freezing out on the outside of the inner container 6 and thus contaminating it. As soon as the thermal shield 21 and the coolant container 14 have cooled completely and the coolant container 14 has been completely filled with nitrogen N2 again, the inner container 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 using the liquid nitrogen LN2. The liquid nitrogen LN2 boils in the cooling line 26 or in the cooling lines 26. The gas bubbles which are produced are supplied as gaseous nitrogen GN2 to the highest point of the cooling system 13, namely the collector 33. This always ensures that the cooling line 26 or the cooling lines 26 are acted upon over their entire length with liquid nitrogen LN2 and thus have a temperature approximately corresponding to the boiling point of the nitrogen N2.

The gas bubbles entrain liquid nitrogen LN2 from the cooling line 26 or from the cooling lines 26 and thus convey this into the return lines 34, 35. The liquid nitrogen LN2 is entrained by the resulting gas bubbles up to a static height of approximately two meters. This does not result in a continuous, but rather a discontinuous delivery of the liquid nitrogen LN2. The liquid nitrogen LN2 is pumped in gushes or in gushes. The liquid nitrogen LN2 conveyed into the return lines 34, 35 and the gaseous nitrogen GN2 are fed back to the coolant tank 14 via the return lines 34, 35. The liquid nitrogen LN2 partially evaporates in the return lines 34, 35. Non-evaporated 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 nitrogen N2. That is, the nitrogen N2 from the cooling line 26 or the cooling lines 26 and Return lines 34, 35 are conveyed in the circuit without a pump having moving parts. The liquid nitrogen LN2 is only conveyed 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 almost without excess pressure. Therefore, the pressure in the coolant tank 14 can be reduced from 1.3 bara usually required to 1.1 bara. This lowering of the pressure in the coolant container 14 leads to a lowering of the boiling temperature of the liquid nitrogen LN2 by 1.5 K. The heat incidence on the helium He is thereby reduced by approximately 5%, so that the helium holding time in comparison to an arrangement without such return lines 34, 35 increases significantly, namely by about three days.

In the case of the transport container 1, a phase separator for separating the liquid nitrogen LN2 from the gaseous nitrogen N2 can advantageously be dispensed with. Such a phase separator comprises movable components that are subject to wear. That is, the phase separator has a limited life. By dispensing with a phase separator, both the costs for the manufacture and maintenance of such a transport container 1 are reduced. Furthermore, dispensing with the phase separator, which is usually arranged on the outside of the outer container 2 as an additional component, also prevents damage to the latter. This simplifies the handling of the transport container 1. The heat incidence caused by the phase separator into the cooling system 13 should also not be neglected. For this reason too, it is advantageous to dispense with the phase separator.

Since cryogenic gaseous nitrogen is only released 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 emerges from the transport container 1, so that in addition to the drastically increased one Holding time for the liquid nitrogen LIN2, as already mentioned, no unwanted icing on the transport container 1 can occur.

Although the present invention has been described using exemplary embodiments, it can be modified in many ways.

Reference symbols used

1

Shipping container

2nd

Outer container

3rd

Base section

4th

Lid section

5

Lid section

6

Inner container

7

Gas zone

8th

Liquid zone

9

Base section

10th

Lid section

11

Lid section

12th

Space

13

Cooling system

14

Coolant tank

15

Base section

16

Lid section

17th

Lid section

18th

Gas zone

19th

Liquid zone

20

Space

21

thermal shield

22

Base section

23

Lid section

24th

Lid section

25th

Space

26

Cooling pipe

27

section

28

section

29

section

30th

section

31

Connecting cable

32

Distributor

33

Collector

34

Return line

35

Return line

36

Blow-off valve

A

Axial direction

d26

Inside diameter

d34

Inside diameter

d35

Inside diameter

G

Direction of gravity

GN2

nitrogen

H1

horizontal

H2

horizontal

Hey

helium

LN2

nitrogen

L2

length

M1

Axis of symmetry

N2

nitrogen

α

Angle of inclination

β

Angle of inclination

Claims (15)

1. Transport container (1) for helium (He), with an inner container (6) for accommodating the helium (He), a coolant container (14) for accommodating a cryogenic fluid (N2), an outer container (2) in which the inner container (6) and the coolant container (14) are accommodated, a thermal shield (21) in which the inner container (6) is accommodated and which is actively coolable with the aid of the cryogenic fluid (N2), wherein the thermal shield (21) has at least one cooling line (26) which is in fluidic connection with the coolant container (14) and in which the cryogenic fluid (N2) can be accommodated for the active cooling of the thermal shield (21), characterized by at least one return line (34, 35), with the aid of which the at least one cooling line (26) is in fluidic connection with the coolant container (14) in order to return the cryogenic fluid (N2) to the coolant container (14).
2. Transport container according to Claim 1, wherein the at least one cooling line (26) is in fluidic connection with a liquid zone (19) of the coolant container (14), and wherein the at least one return line (34, 35) is in fluidic connection with a gas zone (18) of the coolant container (14).
3. Transport container according to Claims 1 or 2, wherein the at least one return line (34, 35) opens into the coolant container (14) above the at least one cooling line (26) with respect to a direction of gravity (g).
4. Transport container according to any one of Claims 1 to 3, wherein a lowest point of the at least one cooling line (26) is in fluidic connection with the coolant container (14).
5. Transport container according to any one of Claims 1 to 4, wherein a highest point of the at least one cooling line (26) is in fluidic connection with the coolant container (14) by means of the at least one return line (34, 35).
6. Transport container according to Claims 1 to 5, wherein an inner diameter (d34, d35) of the at least one return line (34, 35) is larger than an inner diameter (d26) of the at least one cooling line (26).
7. Transport container according to Claim 6, wherein the inner diameter (d26) of the at least one cooling line (26) is greater than 10 millimeters.
8. Transport container according to any one of Claims 1 to 7, wherein the at least one return line (34, 35) is inclined at an inclination angle (β) in the direction of the coolant container (14).
9. Transport container according to any one of Claims 1 to 8, wherein the at least one return line (34, 35) is connected to the thermal shield (21) and is arranged between the thermal shield (21) and the outer container (2).
10. Transport container according to any one of Claims 1 to 9, wherein the cryogenic fluid (N2) boils in the at least one cooling line (26) during the operation of the transport container (1) to actively cool the thermal shield (21) so that gas bubbles of a gaseous phase (GN2) of the cryogenic fluid (N2) arising in the at least one cooling line (26) convey a liquid phase (LN2) of the cryogenic fluid (N2) into the at least one return line (34, 35) in order to return the gaseous phase (GN2) of the cryogenic fluid (N2) and/or the liquid phase (LN2) of the cryogenic fluid (N2) back to the coolant container (14).
11. Transport container according to any one of Claims 1 to 10, wherein a first return line (34) and a second return line (35), which run parallel to one another, are provided.
12. Transport container according to any one of Claims 1 to 11, wherein the coolant container (14) has a relief valve (36) for venting a gaseous phase (GN2) of the cryogenic fluid (N2) from the coolant container (14).
13. Transport container according to any one of Claims 1 to 12, wherein the inner container (6) is completely surrounded by the thermal shield (21).
14. Transport container according to Claim 13, wherein the thermal shield (21) comprises a lid section (24) separated from the coolant container (14) and arranged between the inner container (6) and the coolant container (14).
15. Transport container according to any one of Claims 1 to 14, wherein the coolant container (14) is arranged outside the thermal shield (21).

Images