WO2021069095A1

WO2021069095A1 - Method, device, and fluid tank

Info

Publication number: WO2021069095A1
Application number: PCT/EP2020/025441
Authority: WO
Inventors: Stefan Felbinger
Original assignee: Linde Gmbh
Priority date: 2019-10-09
Filing date: 2020-10-01
Publication date: 2021-04-15

Abstract

The invention relates to a method for measuring a vacuum in a gap (18) between an outer container (2) and an inner container (12) of a fluid container (1) for receiving a cryogenic fluid (F), comprising the steps of: a) connecting (S1) a gas lock (38) to an evacuation nozzle (6) of the fluid container (1); b) filling (S2) the gas lock (38) with a gas (6) which is suitable for freezing in the gap (18); c) establishing (S3) a fluid connection between the gas lock (38) and the evacuation nozzle (6) such that the gas (G) flows into the gap (18); d) freezing (S4) the gas (G) in the gap (18); and e) measuring (S5) the vacuum in the gap (18).

Description

description

Procedure. Device and fluid tank

The invention relates to a method for measuring a vacuum in an intermediate space between an outer container and an inner container of a fluid container for a cryogenic fluid, a device for carrying out such a method and a fluid container with such a device.

Fluid containers for storing or transporting cryogenic fluids, such as nitrogen, argon, oxygen, flelium or the like, can have an outer container and an inner container accommodated within the outer container. An intermediate space is provided between the outer container and the inner container, which space can be evacuated with the aid of an evacuation nozzle. The space can be at least partially filled with insulation, for example in the form of perlite or glass beads. The intermediate space thus serves to isolate or insulate the inner container. If the pressure in the intermediate space rises or the vacuum breaks down in the intermediate space, the insulating effect is no longer given to a sufficient extent and the holding time for the cryogenic fluid is reduced.

The applicant is familiar with in-house prior art in which a gas lock and a vacuum pump are connected to the evacuation nozzle in order to measure or check the vacuum in the space. The gas lock is evacuated with the aid of the vacuum pump so that the evacuation nozzle can be opened and the vacuum checked. With the aid of the vacuum pump, it can thus be prevented that the vacuum pressure in the intermediate space is significantly increased as soon as the evacuation nozzle is opened. However, the use of a vacuum pump is costly and costly in terms of material.

Against this background, the object of the present invention is to provide an improved method for measuring the vacuum.

Accordingly, a method for measuring a vacuum in a space between an inner container and an outer container of a fluid container for Ingestion of a cryogenic fluid proposed. The method comprises the steps: a) connecting a gas lock to an evacuation nozzle of the fluid container, b) filling the gas lock with a gas that is suitable for freezing out in the space, c) opening a fluid connection between the gas lock and the evacuation nozzle, so that the Gas flows into the interspace, d) freezing out the gas in the interspace, and e) measuring the vacuum in the interspace.

The fact that a gas is used that freezes out in the interspace prevents the vacuum pressure in the interspace from being significantly increased when the fluid connection between the gas lock and the evacuation connection is broken. As a result, the use of a vacuum pump can advantageously be dispensed with.

Examples of cryogenic fluids or liquids, or cryogens for short, are, for example, liquid flelium, liquid hydrogen, liquid nitrogen, liquid argon or liquid oxygen. The fluid container can, however, be suitable for holding any cryogenic fluids. The fluid container can be suitable for mobile and immobile applications. In the event that the fluid container is suitable for mobile applications, it can be a transport container.

Particularly preferably, the gas freezes on the outside on or on the inner container and / or in or on an insulation provided in the intermediate space. The insulation can include, for example, perlite, glass beads and / or a so-called multi-layer insulation layer (MLI). The freezing out in the intermediate space according to step d) can therefore include freezing out on the outside on or on the inner container and / or on or in the insulation. The evacuation nozzle is preferably provided on the outer container and is in fluid communication with the intermediate space. This means that an interior of the evacuation connection is also subjected to the vacuum. The gas lock can be filled with the gas, for example, with the aid of a gas cylinder or a gas capsule that is connected to the gas lock.

The "suitability" of the gas to freeze out in the space arises in particular from the fact that the gas has a higher melting point or triple point than an outside temperature of the inner container. The outside temperature of the Inner container can correspond approximately to the boiling point of the cryogenic fluid received in the inner container. “Freezing out” is to be understood in particular as meaning that the gas passes from its gaseous phase directly into its solid phase. The solid phase then settles on the outside on or on the inner container, on or on a thermal shield accommodating the inner container, or on or in the insulation accommodated in the intermediate space. Because the gas changes from the gaseous phase to the solid phase, a significant increase in the vacuum pressure in the intermediate space is reliably prevented.

A “fluid connection” between the gas lock and the evacuation connection is to be understood in particular as meaning that the gas can flow from the gas lock into the evacuation connection and vice versa. The gas can flow at least partially into the space. The "measuring" of the vacuum in the intermediate space can take place, for example, with the aid of a vacuum sensor or a pressure sensor. The measurement does not have to take place directly in the gap. The measurement can, for example, also take place indirectly via the gas lock. This results from the fact that after the fluid connection has been established, the same pressure prevails both in the intermediate space and in the gas lock.

In the event that it is determined in step e) that the vacuum in the intermediate space is not sufficient, the fluid connection between the gas lock and the evacuation nozzle can be separated again. A vacuum pump is then connected to the gas lock, the gas lock is evacuated and the fluid connection between the gas lock and the intermediate space is then re-established. The vacuum pump can now evacuate the gap.

According to one embodiment, the gas lock is flushed with the gas, in particular several times, before or in step b).

This reliably prevents ambient air from entering the space, which could significantly increase the vacuum pressure. In particular, pressure flushing takes place. According to a further embodiment, the gas has a higher pressure than ambient pressure during purging and / or filling of the gas lock.

The pressure of the gas can be, for example, 1.5 bar. In this way, when the gas lock is flushed, it is particularly prevented that ambient air penetrates into the gas lock.

According to a further embodiment, the inner container is filled with the cryogenic fluid before step d).

This ensures that the inner container has a sufficiently low temperature to freeze out the gas.

According to a further embodiment, the vacuum on or in the gas lock is measured in step e).

For this purpose, a vacuum sensor or pressure sensor can be provided on or in the gas lock. A direct measurement of the vacuum in the intermediate space can thus be dispensed with. This simplifies the implementation of the method.

According to a further embodiment, carbon dioxide is used as the gas in step b).

Carbon dioxide is inexpensive, readily available, and easy to transport in small bottles or capsules. The triple point of carbon dioxide is 5.19 bar and -56.6 ° C. This means that carbon dioxide changes from its gaseous phase to the solid phase at relatively high temperatures. Therefore, carbon dioxide is particularly suitable. Alternatively, other gases can also be used. However, carbon dioxide is particularly preferably used.

According to a further embodiment, in step c) the fluid connection between the gas lock and the evacuation connector is established in that a valve body accommodated in the evacuation connector is displaced out of the evacuation connector. For this purpose, an actuating device can be provided which can be part of the gas lock. With the aid of the actuating device, the valve body can be moved out of the evacuating nozzle into a housing of the actuating device in order to establish the fluid connection between the gas lock and the evacuation nozzle.

Furthermore, a device for measuring a vacuum in a space between an inner container and an outer container of a fluid container for receiving a cryogenic fluid is proposed. The device comprises a gas lock that can be connected to an evacuation nozzle of the fluid container, a gas source connected to the gas lock for filling the gas lock with a gas, a linearly displaceable plunger, with the aid of which a fluid connection between the gas lock and the evacuation nozzle can be established, and a vacuum sensor for measuring of the vacuum.

The device is particularly suitable for carrying out the method explained above. In particular, the device is detachably connected to the evacuation connection of the fluid container. For this purpose, for example, a clamping ring or another fastening element can be provided. The gas lock can have the aforementioned actuating device and a connection piece to which the gas source is connected. The vacuum sensor can be a pressure sensor, for example. In order to establish the fluid connection, the plunger can be coupled to the valve body accommodated in the evacuation connection. The valve body can be moved with the aid of the ram. The stamp is in particular displaced linearly into a housing of the actuating device. "Linear" or "translational" means along a straight line. In contrast, a rotational movement can be seen in which the punch would rotate. However, the punch is currently not performing any rotational movement. In particular, the stamp is moved or displaced linearly or translationally along a longitudinal direction of the housing or along an axis of symmetry of the housing.

According to one embodiment, the gas source is a gas cylinder or gas capsule.

This makes the gas source easy to transport. In the event that the gas source is a gas capsule, this can be used, for example, as a single-use disposable item in the gas lock can be screwed in. When the gas capsule is screwed into the gas lock, a membrane is pierced, for example, as a result of which the gas accommodated in the gas capsule flows into the gas lock for filling and / or purging. In particular, the gas source is exchangeable.

According to a further embodiment, the gas source is releasably connected to the device.

As a result, the gas source can easily be exchanged, for example when the gas is used up. The gas source can be connected to the device, for example, with the aid of a form-fitting connection. A positive connection is created by the interlocking or interlocking of two components. A positive connection can be released. For example, the gas source can be screwed or clamped to the device.

According to a further embodiment, the gas lock has an actuating device for actuating the plunger and a connecting piece which is detachably connected to the actuating device and to which the gas source is connected.

For example, the connection piece is positively connected to the actuating device. Alternatively, the connection piece can also be firmly connected to the actuating device, in particular to a connecting piece of a housing of the actuating device. For example, a welded connection can be provided.

According to a further embodiment, the actuating device is releasably connected to the connecting piece with the aid of a clamping ring.

For this purpose, a clamping flange, in particular a so-called small flange, can each be provided on the actuating device and on the connection piece. The clamping flanges are positively enclosed by the clamping ring. With the aid of the clamping ring, a quick and secure connection of the actuating device and the connection piece is thus possible. After removing the connector can For example, a vacuum pump can be connected to the actuating device with the aid of the clamping ring.

According to a further embodiment, the gas lock has a three-way valve for filling and / or purging the gas lock with the gas.

The three-way valve preferably has a vent to which the gas source is connected, and a vent through which ambient air or gas can escape when the gas lock is flushed.

According to a further embodiment, the vacuum sensor is arranged in or on the gas lock.

The vacuum sensor can be arranged, for example, on the actuating device or also on the connection piece. Several vacuum sensors or pressure sensors can be provided.

Furthermore, a fluid container for receiving a cryogenic fluid is proposed. The fluid container comprises an inner container in which the cryogenic fluid can be received, an outer container in which the inner container is received, an evacuated intermediate space provided between the inner container and the outer container, an evacuation nozzle provided on the outer container for evacuating the intermediate space, and such a device , wherein the device is releasably connected to the evacuation nozzle.

As previously mentioned, the fluid container can be suitable for mobile and immobile applications. The inner container is preferably completely received within the outer container. The insulation or insulation can be provided in the intermediate space. The space can be completely or only partially filled with the insulation or insulation. The insulation can for example have perlite, glass beads, a multilayer insulation layer or the like. A thermal shield, which shields the inner container, can also be provided in the intermediate space. The thermal shield can be actively cooled with the aid of nitrogen, for example. The embodiments and features described for the method apply accordingly to the proposed device and / or to the proposed fluid container and vice versa.

In the present case, “a” is not necessarily to be understood as restricting to exactly one element. Rather, several elements, such as two, three or more, can also be provided. Also every other count word used here is not to be understood to the effect that an exact restriction to exactly the corresponding number of elements has to be implemented. Rather, numerical deviations upwards and downwards are possible.

Further possible implementations of the method, the device and / or the fluid container also include combinations, which are not explicitly mentioned, of features or embodiments described above or below with regard to the exemplary embodiments. The person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the method, the device and / or the fluid container.

Further advantageous configurations of the method, the device and / or the fluid container are the subject matter of the dependent claims and the exemplary embodiments of the method, the device and / or the fluid container described below. In the following, the method, the device and / or the fluid container are explained in more detail on the basis of preferred embodiments with reference to the attached figures.

1 shows a schematic sectional view of an embodiment of a fluid container;

FIG. 2 shows the detailed view II according to FIG. 1;

3 shows a schematic view of an embodiment of a device for measuring a vacuum in an intermediate space between an inner container and an outer container of the fluid container according to FIG. 1; and FIG. 4 shows a schematic block diagram of an embodiment of a method for measuring a vacuum in an intermediate space between an inner container and an outer container of the fluid container according to FIG. 1.

In the figures, elements that are the same or have the same function have been given the same reference symbols, unless otherwise stated.

1 shows a greatly simplified schematic view of an embodiment of a fluid tank or fluid container 1 for a cryogenic fluid F. FIG. 2 shows the detailed view II according to FIG. 1. In the following, reference is made to FIGS. 1 and 2 simultaneously.

The fluid container 1 can also be referred to as a fluid tank. The fluid container 1 can be used for mobile applications and for immobile applications. In the event that the fluid container 1 is used in a mobile manner, it can also be referred to as a transport tank or transport container. Examples of cryogenic fluids F or liquids, or cryogens for short, are, for example, liquid Flelium Fle (boiling point 1 bara: 4.222 K = -268.928 ° C), liquid hydrogen H2 (boiling point:

1 bara: 20.268 K = -252.882 ° C), liquid nitrogen N2 (boiling point: 1 bara: 77.35 K = -195.80 ° C), liquid oxygen 02 (boiling point: 1 bara: 90.18 K = -162 , 97 ° C) or liquid argon Ar (boiling point: 1 bara: 87.15 K = -186 ° C).

The fluid container 1 comprises an outer container 2. The outer container 2 is made of stainless steel, for example. The outer container 2 comprises a tubular or cylindrical base section 3, which is closed on both sides with the aid of a cover section 4, 5, in particular with the aid of 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 cover sections 4, 5 are curved. The cover sections 4, 5 are curved in opposite directions, so that both cover sections 4, 5 are curved outward with respect to the base section 3. The outer container 2 is fluid-tight, in particular gas-tight. The fluid container 1 has a central or symmetry axis M, to which the fluid container 1 or the outer container 2 is constructed rotationally symmetrical. An evacuation nozzle 6 can be attached to the outer container 2. The evacuation connection 6 can be tubular and is, for example, welded into the base section 3. The evacuation connector 6 thus breaks through the outer container 2, and in particular the base section 3. As shown in FIGS. 1 and 2, the evacuation connector 6 can be arranged on the underside of the fluid container 1 with respect to a direction of gravity g. The evacuation nozzle 6 can, however, also be provided on the top side of the fluid container 1 on the side of the latter or on one of the cover sections 4, 5. The evacuation nozzle 6 can be positioned as desired.

As FIG. 2 shows, the evacuation connector 6 comprises a sealing plug or valve body 7, which is received in the evacuation connector 6. The evacuation nozzle 6 is protected with a safety cap 8. The safety cap 8 is connected to the evacuation nozzle 6 with the aid of a clamping ring 9. For this purpose, the evacuation nozzle 6 and the safety cap 8 have clamping flanges 10, 11, in particular so-called small flanges. After loosening the clamping ring 9, the safety cap 8 can be removed from the evacuation nozzle 6.

Returning now to FIG. 1, the fluid container 1 furthermore comprises an inner container 12 for receiving the cryogenic fluid F. The inner container 12 is also made of stainless steel, for example. As long as the cryogenic fluid F is in the two-phase region, a gas zone 13 with vaporized fluid F and a liquid zone 14 with liquid fluid F can be provided in the inner container 12. The inner container 12 is fluid-tight, in particular gas-tight, and can include a blow-off valve for controlled pressure reduction. Like the outer container 2, the inner container 12 comprises a tubular or cylindrical base section 15 which is closed on both sides by cover sections 16, 17, in particular a first cover section 16 and a second cover section 17. The base section 15 can have a circular or approximately circular geometry in cross section.

The inner container 12, like the outer container 2, is designed to be rotationally symmetrical to the axis of symmetry M. An intermediate space 18 provided between the inner container 12 and the outer container 2 is evacuated with the aid of the evacuation nozzle 6. Insulation or insulation 19 in the form of perlite, glass beads and / or a multilayer insulation layer, in particular a so-called Multi Layer Insulation (MLI) can be provided. Such a multilayer insulation layer can comprise alternately arranged layers of aluminum foil and glass paper. The layers of aluminum foil serve as a reflector and as a mechanical fixation for the layers of glass paper, which serve as spacers. The aluminum foil can be perforated and embossed. For example, the multilayer insulation layer can be applied to the inner container 12. The space 18 can be completely or partially filled with the aid of the insulation 19.

The inner container 12 can furthermore be accommodated in a thermal shield (not shown). The thermal shield is arranged in the space 18 provided between the inner container 12 and the outer container 2. The thermal shield can, for example, be actively coolable or actively cooled with the aid of liquid nitrogen. In the present case, “active cooling” is to be understood as meaning that the liquid nitrogen for cooling the thermal shield is passed through the latter or is passed along it. The thermal shield is cooled to a temperature that roughly corresponds to the boiling point of nitrogen. With the help of the thermal shield, the inner container 12 can be shielded from the outer container 2. However, the thermal shield is optional. The thermal shield can be provided in addition to the insulation 19.

The fluid container 1 can be supported on a foundation 22, for example, via support feet 20, 21 attached to the outer container 2. The foundation 22 can for example be a concrete slab. As mentioned above, the fluid container 1 can be used either for mobile or for immobile applications. The support feet 20, 21 are optional.

3 shows a schematic view of an embodiment of a device 23 for checking or measuring the vacuum in the intermediate space 18. The device 23 can be flange-mounted on the evacuation nozzle 6. As FIG. 3 shows, the device 23 is fastened to the evacuation nozzle 6 with the aid of the clamping ring 9 after the safety cap 8 has been removed. The evacuation nozzle 6 comprises an interior space 24 which is in fluid connection with the intermediate space 18. The device 23 comprises an actuating device 25 for actuating the valve body 7. The actuating device 25 has a housing 26 on which a valve spindle 27 and a locking spindle 28 are rotatably mounted. The actuating device 25 further comprises a plunger 29. With the aid of the locking spindle 28, the plunger 29 can be coupled to the valve body 7 such that the valve body 7 can be displaced along a longitudinal direction L of the housing 26 with the aid of the valve spindle 27. The longitudinal direction L is oriented parallel to the direction of gravity g or corresponds to it.

A connecting piece 30 is flanged to the side of the housing 26, that is to say perpendicular to the longitudinal direction L. The connecting piece 30 can be welded to the housing 26. A connecting piece 32 is flanged to the connecting piece 30 with the aid of a clamping ring 31. For this purpose, the connection piece 30 and the connection piece 32 can have clamping flanges 33, 34, in particular so-called small flanges. The connection piece 32 can, however, also be formed in one piece, in particular in one piece, with the connection piece 30. "One-piece" here means that the connecting piece 30 and the connecting piece 32 are not composed of several individual components, but rather form a common component. For example, the connecting piece 32 can be welded to the connecting piece 30. "In one piece of material" means in the present case that the connecting piece 30 and the connecting piece 32 are made continuously from the same material.

The connection piece 32 comprises a three-way valve 35. The three-way valve 35 is connected to the connection piece 32. The three-way valve 35 comprises a ventilation 36 and a vent 37. The actuating device 25 and the connection piece 32 together form a gas lock 38 of the device 23.

The device 23 further comprises a gas source 39 which is connected to the ventilation 36 of the three-way valve 35. With the aid of the gas source 39, a gas G can be supplied to the gas lock 38. The gas G can be carbon dioxide, for example. However, the gas G is particularly preferably carbon dioxide. Carbon dioxide has a triple point at -56.6 ° C and 5.19 bar. The device 23 further comprises a pressure sensor or vacuum sensor 40. The vacuum sensor 40 can be attached, for example, in or on the connection piece 32, on the connection stub 30 or the housing 26. The housing 26 comprises a clamping flange 41, in particular a small flange, around which the clamping ring 9 engages. The housing 26 is constructed to be rotationally symmetrical with respect to a central or symmetry axis 42.

The functionality of the device 23 is explained below. As previously explained, the device 23 is suitable for determining or measuring the vacuum in the intermediate space 18. For this purpose, after releasing the clamping ring 9, the safety cap 8 is first released from the evacuation nozzle 6. The gas lock 38 is then fastened to the evacuation nozzle 6 with the aid of the clamping ring 9. The valve body 7 initially remains in its position shown in FIG. 3. The plunger 29 is connected to the valve body 7 with the aid of the locking spindle 28.

Then, with the aid of the gas source 39 and the three-way valve 35, the connection piece 32, the connection stub 30 and at least in sections the housing 26 are flushed several times with the gas G. A pressure of the gas G is higher than an ambient pressure U. In this way, ambient air can be prevented from penetrating into the gas lock 38. For example, the pressure of the gas G is 1.5 bar.

After the gas lock 38 has been flushed and filled with the gas G, the three-way valve 35 is closed so that the connection piece 32, the connection stub 30 and the housing 26 are at least partially filled with the gas G and the gas G cannot escape from the gas lock 38 . As mentioned above, the gas G has a higher pressure than the ambient pressure U.

The valve body 7 is now displaced out of the evacuation nozzle 6 into the housing 26 along the longitudinal direction L, that is to say in the direction of gravity g, with the aid of the ram 29. In this way, a fluid connection is established between the evacuation nozzle 6, in particular its interior space 24, and the connection nozzle 30 or the connection piece 32.

The punch 29 is displaced linearly into the housing 26. "Linear" means along a straight line. In contrast to this, a rotational movement can be seen in which the punch 29 would rotate. However, the punch 29 is just leading no rotational movement. In particular, the punch 29 is moved or displaced linearly along the longitudinal direction L or along the axis of symmetry 42. The punch 29 is constructed to be rotationally symmetrical to the axis of symmetry 42. The above statements apply accordingly to the valve body 7, which is connected to the plunger 29.

The gas G can now flow into the space 18 via the evacuation nozzle 6. As soon as the gas G flows into the evacuated intermediate space 18, it freezes out in the intermediate space 18 and in particular on or on the inner container 12. In the present case, “freezing out” is to be understood as meaning that the gas G changes from its gaseous phase directly into its solid phase. The gas is thus deposited as a solid on the outside or on the inner container 12 and / or on or in the insulation 19. Because the gas G freezes out in the interspace 18, an increase in the vacuum pressure in the interspace 18 is prevented.

The vacuum in the space 18 can now be checked with the aid of the vacuum sensor 40. There is thus no need for a vacuum pump to measure the vacuum in the space 18. If it turns out that there is no longer a sufficient vacuum in the space 18, after the valve body 7 is moved into the evacuation nozzle 6 again, a vacuum pump can be connected to the connection nozzle 30 with the aid of the clamping ring 31 in order to evacuate the space 18 .

4 shows a schematic block diagram of an embodiment of a method for measuring the vacuum in the intermediate space 18. In a step S1, the gas lock 38 is connected to the evacuation nozzle 6 of the fluid container 1. The gas lock 38 is then flushed and / or filled with the gas G in a step S2. The gas G is suitable for freezing out in the intermediate space 18 and in particular on the inner container 12. This suitability of the gas results from the fact that it has a melting point or triple point which is above an external temperature of the inner container 12 and / or the insulation 19.

In a step S3, a connection between the lock and the evacuation nozzle 6 is opened, so that the gas G flows into the intermediate space 18 can. The connection can be opened by displacing the valve body 7 with the aid of the actuating device 25 along the longitudinal direction L out of the evacuation nozzle 6 into the housing 26 of the actuating device 25.

In a step S4, the gas G freezes out in the space 18. The gas G can freeze out on or on the inner container 12 and / or the insulation 19. As previously mentioned, the inner container 12 may have a thermal shield. In this case, the gas G freezes on the thermal shield.

In a final step S5, the vacuum is measured in an intermediate space 18. For this purpose, the vacuum can be measured on or in the gas lock 38. Before the gas G is frozen out in step S4, it may be necessary to fill the inner container 12 with the cryogenic fluid F in order to achieve a sufficiently low temperature for the gas G to freeze out. When purging the gas lock 38, the gas G has a higher pressure than the ambient pressure U. For example, the gas G has a pressure of 1.5 bar. In this way, the penetration of ambient air into the gas lock 38 can be prevented. Although the present invention has been described on the basis of exemplary embodiments, it can be modified in many ways.

References used

1 fluid container

2 external containers

3 base section

4 cover section

5 cover section

6 evacuation ports

7 valve bodies

8 safety cap

9 clamping ring

10 clamping flange

11 clamping flange

12 inner containers

13 gas zone

14 liquid zone

15 base section

16 cover section

17 cover section

18 space

19 insulation

20 support leg

21 support leg

22 foundation

23 device

24 interior

25 actuating device

26 housing

27 valve spindle

28 locking spindle

29 stamps

30 connecting pieces

31 clamping ring

32 connector

33 clamping flange 34 clamping flange

35 three-way valve

36 Ventilation

37 Venting 38 Gas lock

39 gas source

40 vacuum sensor

41 clamping flange

42 axis of symmetry

F fluid g direction of gravity

G gas

L longitudinal direction M axis of symmetry

51 step

52 step

53 step

54 step S5 step

U ambient pressure

Claims

1. A method for measuring a vacuum in a space (18) between an inner container (12) and an outer container (2) of a fluid container (1) for receiving a cryogenic fluid (F), comprising the steps of: a) connecting (S1) a Gas lock (38) on an evacuation nozzle (6) of the fluid container (1), b) filling (S2) the gas lock (38) with a gas (G) which is suitable for freezing out in the intermediate space (18), c) freezing points ( S3) a fluid connection between the gas lock (38) and the evacuation nozzle (6), so that the gas (G) flows into the intermediate space (18), d) freezing out (S4) of the gas (G) in the intermediate space (18), and e) measuring (S5) the vacuum in the gap (18).

2. The method according to claim 1, wherein before or in step b) the gas lock (38) is flushed with the gas (G), in particular several times.

3. The method according to claim 2, wherein the gas (G) has a higher pressure than ambient pressure (U) during purging and / or filling of the gas lock (38).

4. The method according to any one of claims 1-3, wherein before step d) the inner container (12) is filled with the cryogenic fluid (F).

5. The method according to any one of claims 1-4, wherein in step e) the vacuum on or in the gas lock (38) is measured.

6. The method according to any one of claims 1-5, wherein in step b) carbon dioxide is used as gas (G).

7. The method according to any one of claims 1-6, wherein in step c) the fluid connection between the gas lock (38) and the evacuation nozzle (6) is established in that a valve body (7) received in the evacuation nozzle (6) is made the evacuation nozzle (6) is moved out.

8. Device (23) for measuring a vacuum in an interspace (18) between an inner container (12) and an outer container (2) of a fluid container (1) for receiving a cryogenic fluid (F), with one connected to an evacuation nozzle (6) of the fluid container (1) connectable gas lock (38), a gas source (39) connected to the gas lock for filling the gas lock (38) with a gas (G), a linearly displaceable plunger (29), with the aid of which a fluid connection between the gas lock (38) and the evacuation nozzle (6) can be produced, and a vacuum sensor (40) for measuring the vacuum.

9. Apparatus according to claim 8, wherein the gas source (39) is a gas cylinder or gas capsule.

10. The device according to claim 8 or 9, wherein the gas source (39) is detachably connected to the device (23).

11. Device according to one of claims 8-10, wherein the gas lock (38) has an actuating device (25) for actuating the plunger (29) and a connecting piece (32) which is detachably connected to the actuating device (25) and to which the gas source is connected is.

12. The device according to claim 11, wherein the actuating device (25) is detachably connected to the connecting piece (32) with the aid of a clamping ring (31).

13. Device according to one of claims 8-12, wherein the gas lock (38) has a three-way valve (35) for filling and / or purging the gas lock (38) with the gas (G).

14. Device according to one of claims 8-13, wherein the vacuum sensor (40) is arranged in or on the gas lock (38).

15. Fluid container (1) for receiving a cryogenic fluid (F), with an inner container (12) in which the cryogenic fluid (F) can be received, an outer container (2) in which the inner container (12) is received, a provided between the inner container (12) and the outer container (2) evacuated intermediate space (18), an evacuation nozzle (6) provided on the outer container (2) for evacuating the intermediate space (18), and a device (23) according to one of claims 8-14, wherein the device (23) is detachable with the evacuating nozzle (6) is connected.