DE1240536B - Container for liquefied gases - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

F17c

German class: 17 g- 4

Number: 1240536

File number: U123171 a / 17 g

Filing date: December 27, 1965

Open date: May 18, 1967

The invention relates to a double-walled, thermally insulated container for low-boiling liquefied Gases, consisting of an inner vessel and one this at a distance, forming an evacuated, heat-insulating space surrounding the outer casing, the outer casing has an upwardly directed neck part in which a top connected to the inner vessel the neck tube closed to form a steam chamber is arranged concentrically, the upper, protruding from the neck and means for venting gas carrying end the outer Forms part of the steam chamber.

It is known that in some containers for the storage of low-boiling liquefied gases, especially of liquefied helium, pulsations of the pressure occur under certain conditions. This phenomenon significantly accelerates the evaporation of the liquid from the container. These pulsations consist of periodic movements of colder gas from the vapor space through the liquid to the warm end of the filling and filling line and back into the steam room. As a result, ambient heat is introduced into the inner vessel, whereby the Evaporation rate of the liquid is increased. These pulsations arise spontaneously certain conditions of temperature, pressure and the shape and design of the discharge devices. You can use both vertical and horizontal lines of gas or liquid appear. Probably they are primarily due to large temperature differences along these lines traced back. These pulsations are therefore also referred to as thermal oscillations. The occurrence of even small thermal oscillations is undesirable, and strong oscillations are intolerable. The oscillations can lead to the fact that the contents of the container in a few hours evaporates.

In thermal oscillations, gas is between areas of different temperatures and pressures moved quickly through connecting lines or rooms. Through this pulsation of the vapor pressure heat is conveyed to the cold areas. When storing liquid helium, the supply has from heat to the cold area or the liquid a very rapid evaporation of the liquid Result in heliums. As the liquid evaporates, the gas pressure on the cold one increases End. The cold gas expands into the warm areas, where its temperature will be and at the same time Containers for liquefied gases

Applicant:

Union Carbide Corporation,
New York, NY (V. St. A.)

Representative:

Dipl.-Ing. H. Görtz, patent attorney,

Frankfurt / M., Schneckenhofstr. 27

Named as inventor:

Austin Joseph Short, Kenmore, N.Y. (V. St. A.)

Claimed priority:
V. St. v. America December 29, 1964
(421790)

Increase pressure. The gas then expands back into the cold area, creating a Oscillation or cyclical movement of the gas.

The object of the invention is to create a device for storing liquefied gases with the aid of which such thermal oscillations can be controlled and, in particular, reduced. This object is achieved according to the invention in that a throttle line is connected to the outer part of the steam chamber, which leads to a damping chamber, the throttle line having an inner diameter of at least 1.6 mm and a length to inner diameter ratio of at least 52 and that at least The volume of the damping chamber, which is 5 cm ^3, is greater than the volume of the outer part of the steam chamber and the inner length of the damping chamber is at least twice the inner diameter of the throttle line.

The term "outer part of the vapor chamber" of the container includes the inner part all pressure relief devices within the chamber. If e.g. a safety valve with the When the steam chamber is connected, the outer part of the steam chamber includes the parts that are inside of the safety valve.

With the invention, the advantage is achieved that thermal oscillations in containers for liquefied Gases are either significantly reduced or suppressed entirely, and this is made possible by the combination of a throttle line for the steam

709 580/91

with a certain minimum diameter, a certain ratio of length to diameter, a damping chamber with a certain minimum content and a certain ratio of this Contents to the outer part of the steam chamber. A damping chamber of its own without a throttle tube for the steam does not prevent the occurrence of thermal oscillations. It is not the same possible by combining the individual components with other dimensions the appearance of To suppress oscillations effectively. So arise z. B. Large diameter and smaller pipes Length of thermal oscillations that are even stronger than without the use of such lines.

An advantageous embodiment of the invention is that the throttle line has an inner diameter of 3.8 to 6.3 mm, that the ratio of the length of the throttle line to its diameter is between 100 and 400 and that the damping chamber has a capacity of 20 to 2000 cm ³ has.

A particularly advantageous feature of the invention is that a wide opening Filling valve of the liquid is arranged on the outer part of the vapor chamber. Preferably leads in accordance with a further feature of the invention, a removable, slidable fluid conduit gastight through the outer part of the steam chamber to the lower part of the inner vessel. This liquid line is advantageously passed through the filling valve. To the container To completely empty it, a liquid line reaching to the bottom of the inner vessel is required.

Such a liquid line, however, results in an unavoidable additional incidence of heat. Due to the advantageous development of the invention, the liquid line can now during the Storage, i.e. if no liquid is to be removed, must be removed to prevent exposure to heat to reduce. As explained at the outset, this also reduces the thermal oscillations. A certain improvement is achieved in that the liquid line consists of two pipes exists between which there is insulation.

Finally, there is another embodiment of the invention that the throttle line and A second arrangement, also consisting of a throttle line and a damping chamber, consists of a damping chamber existing arrangement is connected in parallel. This is preferably attached to an in the steam chamber Reaching, made of poorly thermally conductive material pipe connected. If Ice forms in the neck tube to which the first damping arrangement is connected and thus a blockage has occurred, the second damping arrangement is still working.

The device according to the invention does not need to completely suppress the thermal oscillation, but reduces it in any case to such an extent that little heat is passed into the liquid container will. The energy required for pulsing is likely to be required when conveying the gas through the Throttle line and consumed when compressing the gas in the damping chamber.

The energy supplied to the gas in the damping chamber is not sufficient to generate the heated gas lead back through the throttle line into the steam chamber within such a time that the Oscillation is promoted. The effectiveness of the device according to the invention depends on its dimensions away; but in no case is a throttle line with a length of less than about that Effective 52 times the diameter. Optimal suppression of the oscillations is likely achieved when a resonance does not occur. In this case, no heat is returned to the cold area of the container. As a result, the pulsation is stopped. There is a tendency to do so but further what shows up when the outer damping chamber is removed; in this case the thermal oscillation on again immediately. If the length of the throttle line is less than 52 times its diameter, it does not throttle enough to prevent the transmission of the pressure pulse from the To delay damping chamber back and thus an amplification of the pulsation of the gas in the to prevent outer part of the steam chamber. The inner diameter of the throttle line must be at least 1.6 mm to allow a corresponding amount of warm gas from the outer part of the Steam chamber get into the damping chamber

as and thereby delay the pulsation. Of the effective inner diameter of pipes also refers to pipes with a non-circular shape Cross-section, e.g. B. with an oval cross-section which is equivalent to the cross-section of a circular one Line with a diameter of at least 1.6 mm.

The invention will be explained in more detail with reference to the drawing, which shows two exemplary embodiments It shows

Fig. 1 is a longitudinal section through an embodiment of the container according to the invention and FIG. 2 shows a longitudinal section through a modified one Embodiment.

According to FIG. 1, the container 10 consists of an inner vessel 11 and an outer casing 12. The intermediate space 13 is evacuated to a pressure below 10 mm Hg to prevent infiltration Decrease heat from the atmosphere. The space 13 can be thermally fixed with a fixed be filled with insulating material, e.g. B. with alternating layers of poorly conductive paper and Rays reflecting aluminum foils. The walls forming the intermediate space 13 can also with a highly reflective surface, e.g. B.

Silver, be plated.

An elongated upper portion 14 of the container 10 of reduced cross-section is at the top open to give access to the inner vessel 11. A neck tube 15 is concentric within this section 14 arranged and leak-tight connected at its lower end to the walls of the hole 16 in the top of the inner vessel 11. The top of the neck tube 15 is Leak-tightly connected to the upper end of the container section 14. The neck tube 15 is preferably made of a less conductive material, e.g. stainless steel or a phenol-formaldehyde resin, that is reinforced with paper. In the embodiment shown, the neck tube 15 forms a Steam pipe through the outer housing and the walls of the inner vessel, the inner The end opens into the upper part of the inner vessel and the outer end into the outer part 17

the steam chamber of the container 10 ends. In this particular case, the neck tube also serves as a fixed one Connect the inner vessel U to the outer envelope 12. Further vertical supports can optionally be provided at the lower end of the inner vessel. Lateral supports can also be used can be used for the inner vessel, as any person skilled in the art knows.

The outer part 17 of the steam chamber is leaky

Sizing the pressure in the outer part 17 of the steam chamber continues as a pressure pulse the throttle tube 24, the contents of the damping chamber 25 being slightly compressed. the 5 damping chamber 25 must have an inner length of at least twice the inner diameter of the throttle line 24 to achieve the necessary mixing and friction. The steam in the chamber 25 does not contain

closely connected to the top of the neck, enough energy to cause reflux tube 15 and forms an extension of the same, through line 24 in such a short time that a powder can optionally also be partially isolated. thundering burst of warmer steam into the interior As noted, the outer part 17 contains the vessel that takes place. Hence the original Steam chamber the gas that is directly adjacent thermal oscillation does not amplify the cycle and communicating with the outer part of the 15 is stopped and the oscillation stops. Neck tube 15. This part ends in different As already said, the content of the damping

Pipes and valves. The outer part 17 of the steam chamber 25 must be at least 5 cm ³ and must usually have a temperature of about at least as large as the outer part 17 of the surrounding area, except in cases when the steam chamber. Smaller damping chambers liquefied gas is introduced or withdrawn. In these latter cases, there are insufficient time delays caused by this part of the pressure pulse that cools down sharply, which is caused by the conduit 24 due to the flow of cold steam. This flows back so that an intensification of the pulsation in liquid gas is not avoided in the container 10 by the inlet of the vapor chamber, filling line 18 with the inlet valve 19 is filled. If required, a second steam

Liquid flows through the neck tube 15 into the inner 25 line to be connected to the neck tube 15. If Storage vessel 11. The liquefied gas, e.g. B. helium, the first steam pipe happens to be with ice or solid air is stored at superatmospheric pressure. If there is a blockage, the other line of the the storage lasts a long time, this pressure rises, where- gas pressure is passed inside the container 10, infiltrates with heat and an evaporation takes place- This second steam line has a pipe 27 from little finds. In order to avoid too high a vapor pressure, conductive metal or plastic, preferably the safety devices are provided, as is arranged centrally within the neck tube 15 z. B. the safety valve 20 and the rupture disc and is so large that an annular gap 21, which is created by 28 in connection with the steam chamber. The top of the second steam die Line 22 stand through. Steam can be discharged from line 27 and is provided with a safety valve 29 the container 10 optionally by means of the valve 35 and is connected to the liquid line 18 with -23 be drained on line 22. As already by means of valve 19. The pipe is also connected noted above, the term "outer part with a second throttle line 30 means the same the steam chamber ”should also have the same dimensions as the first throttle line Safety valve 20, the rupture disc 21 and the 24. The opposite end of the line 30 is Line 22, but not those parts that are connected in connection with a second damping chamber 31, bond with the surrounding atmosphere. which should also have the same dimensions as the

The throttle line 24 for the steam has a first damping chamber 25. This second damping length, which is at least 52 times as large as the inflation chamber, has the vent valve 32. The inner diameter. One end of this line is leak-tightly connected to the outer part of the steam chamber of the second steam-tight connection with the outer part 17 of the steam line also includes the part of the tube 27, chamber, and the other end is in the same way that outside the extended part the äußeverbunden 25 with the damping chamber this letz- ren housing 14 is located around the neck tube 15, tere may be provided with a vent valve also closes this part also includes the inner 26. its content is at least 5 cm ^3, and must in parts of the filling valve 19 and in any case be greater than the contents of the outer 50 valve 29.

Part 17 of the steam chamber. The inner length "α" during normal operation is the second

Steam line 27 is closed, and the steam flows from the inner vessel 11 through the annular Gap 28 to the outer part 17 of the steam chamber and then through the first conduit 22 to the drain valve 23. When the annular space 28 is clogged with solid ice, the flows pressurized steam through the safety valve 29. You can also use the heated gas

above the liquid. The cold gas expands ^6o through the restrictor conduit 24 to the first Dämpfungsin the outer portion can reach 17 of the steam chamber and comparable chamber 25 and the valve or ursacht an increase of temperature and Druk- through line 30 to the second damping chamber kes in this area. The gas then expands backwards 31 and through the drain valve 32. Usually, it expands downwards into the cold inner vessel 11. But not without prior notice, and the valves on the damping ^{directions according to the invention, this cycle 6} 5 chambers 25 and 31 are closed, repeated, with a thermal oscillation developing. 2 shows another embodiment of FIG

stands. The device according to the invention becomes the device according to the invention. The device is the thermal oscillation, however, regulated, since the powder shown in FIG. 1 is similar, differs

of the damping chamber 25j measured perpendicular to the axis bb of the line 24, must be at least twice as large as the inner diameter of this line.

During the storage of the liquefied gas, cold vapor is produced in the by evaporation upper end of the inner vessel 11. As the liquid evaporates, the gas pressure rises

but essentially through the use of a removable liquid line. This line will used for filling liquefied gas into the inner vessel 11 and for drawing off the liquid out of him. For each of these purposes, the part 35 is opened by the valve 36, which is a ball valve or a slide valve can be introduced. The inner end extends to near the bottom of the inner vessel 11. A pressure-tight seal is located between the inner wall of the Ball valve 36 and the outer wall of the line 35 and consists of a sealing ring 37.

The part 35 includes an inner fluid conduit 38, which is preferably concentric within the outer line 39 is arranged. Suitable seals create an annular evacuated one Gap 40, which reduces the infiltration of atmospheric heat. Of the evacuated isolated space 40 is intended to allow rapid evaporation during filling and Prevent liquid overflow. A valve 41 can be provided at its upper end. at When not in use, the part 35 can be pulled out through the neck tube 15, whereby by closing the Ball valve 36 the outer part 17 of the steam chamber is closed.

The device according to FIG. 2 does not contain a second vapor discharge line as in FIG. 1. Therefore, also a second throttle tube and a second damping chamber not needed. The outer part 17 of the Vapor chamber of the container 10 includes the contents of the neck tube 15 via the portion 42 with the reduced Diameter, the contents below the sliding sealing ring 37, the contents of the line 22 and the internal contents of the safety valve 20 and the rupture disc 21. The throttle line 24 for the Steam is connected at one end to the outer part 17 of the steam chamber and at the other End with the damping chamber 25. You can also use a part 35, the container with a second fuse according to FIG. 1 contains e.g. B. by inserting through the wide open valve 19 and a inner or second tube 27.

The advantages achieved by the invention were in a number of tests in double-walled containers been tested with liquid helium. Thermal oscillations were perceived in these experiments determined according to their strength in various ways. In some cases the oscillations were strong enough to cause a buzzing noise of the container, that also pressure fluctuations of the manometer were recognizable or by vibrating a rubber hose that you can feel. In other Cases the thermal oscillations were weaker. You could only get them through increased evaporation rates determine which exceeded the usual evaporation rates for the given container. In all cases it was true the thermal oscillation is only considered to be eliminated if it is immediately, d. H. within a minute, suppressed was.

Example I.

In a container with a capacity of 110 l of liquid helium, the evaporation was l% daily. Thermal oscillations were not found. The neck tube had an outer diameter of 19 mm and a wall thickness of 0.38 mm. To the risk of ice and formation To avoid solid air in this neck tube, a second vent line in the form of a tube was added of 16 mm outer diameter and 13 mm inner diameter arranged in the neck, wherein it as the fig. 1 shows protruding 13 mm below the neck tube. This inner tube was made of paper reinforced phenol-formaldehyde resin. When this second tube was inserted, significant ones were created thermal oscillations, so strong that the evaporation losses were more than 10 per cent per day. After installing a damping device with the throttle line 24 and the chamber 25 and one second damping device with the line 30 and the chamber 31, it was found that different Combinations successfully suppressed the thermal oscillation, so that the evaporation losses sank again to about 1 per cent daily. It was found that the first and second damping chambers 25 and 31 could be cooled to at least -77 ° C and heated to at least 135 ° C could without their ability to suppress the thermal oscillations suffered. Certain other combinations of choke lines and damping chambers have not been as successful. So differed the throttle lines with an inner diameter of 1.6 mm from larger ones Tubes with an outer diameter of 9.5 mm and an inner diameter of 6.3 mm with an evacuated insulating space created by an open ball valve in the neck of the vessel were introduced close to the bottom. This caused thermal oscillations in this line on. Throttle lines and damping chambers were then connected to the inner tube with the diameter 6.3 mm of this line connected. The experimental results obtained according to Example I are summarized in Table A.

Table A.
Thermal oscillation in containers for 1101 liquid helium

Throttle line length Outer part Damping chamber Length to diameter Elimination Inside diameter cm the steam chamber cm ³ the the thermal mm 3.8 cm ³ 25th Throttle line oscillation 1.6 7.6 5 25th 23 no 1.6 20 to 25 5 25th 46 Yes 1.6 51 5 1000 123 Yes 3.8 91 375 700 133 Yes 5.3 104 40 1000 171 Yes 5.3 38 to 51 375 1000 195 Yes 6.3 375 60 to 80 Yes

Table A (continued)

10

Throttle line 51 Outer part Damping chamber Length to diameter Elimination Inside diameter | length 61 the steam chamber cm ³ the the thermal mm j cm cm ³ 330 Throttle line oscillation 7.9! 2.5 40 1000 3.2 no 7.9 ι 28 375 1000 35 no 7.9 36 375 1000 45 no 7.9 j 41 375 1000 51 no 7.9 53 375 1000 67 Yes 12.7 43 375 1000 34 no 12.7 375 1000 40 no 12.7 375 48 no

Example II

In a container for liquid helium with a capacity of about 251 and a second Vent line experienced an evaporation loss of 2.0% daily initially immediately after filling of helium. The next morning the evaporation loss had increased to 8.2%. Obviously thermal oscillations had occurred, which was also determined by a noticeable vibration could be. The installation of certain damping devices immediately interrupted the Oszilao lations, and the evaporation losses of helium sank to 1.2 per cent daily. The results of these experiments are summarized in Table B.

Table B.
Thermal oscillation in a container for 25 liters of liquid helium

Throttle line length Outer part Damping chamber Length to diameter Elimination Inside diameter cm the steam chamber cm ³ the the thermal mm 51 cm ³ 1000 Throttle line oscillation 3.2 101 1000 1000 160 Yes 3.2 178 1000 1000 320 Yes 3.2 24 1000 560 no 3.2 76 1000 6.3 51 1000 76 Yes 3.2 13th 1000 6.3 58 1000 700 36 no 5.3 58 20th 1000 110 Yes 5.3 58 28 1000 110 Yes 5.3 51 100 700 110 Yes 6.3 51 20th 1000 80 Yes 6.3 56 100 1000 80 Yes 6.3 100 88 Yes

Examination of Tables A and B shows that the ratio of the length of the choke line to its Diameter must be greater than 52, otherwise the thermal oscillations will not be dampened. For example, according to Table A, there was a throttle tube with a diameter of 7.9 mm and a length of 42 cm has no effect because the ratio value was 51. A tube 53 cm long suppressed it but successful the thermal oscillation. The reasons for this have not yet been clarified. It is possible, that the shorter tube did not dampen the pressure pulses enough to suppress oscillation.

On the basis of the tests described above, the throttle line preferably has an inner diameter of 3.8 to 6.3 mm, and the ratio of the length to the diameter should be between about 100 and 400. The damping chamber preferably has a content of about 20 to 2000 cm ³ .

The drawings illustrate certain embodiments of the invention in detail. Changes to the However, devices can be made, and certain details can also be omitted without dated Deviate subject of the invention.

So needs ζ. B. the steam line going into the interior Vessel leads not necessarily to hold the inner vessel and the outer envelope together at the same time; this line can also be introduced completely separately from supports or not in a straight direction be. The throttle line for the steam can also have the shape of a bend or loop and can run inside the damping chamber and does not just need to go up to the wall to lead this chamber.

According to another embodiment, the damping chamber can be inside the evacuated insulating Be attached between the space between the inner vessel and the outer casing. Here, of course, the throttle line can also extend into this evacuated intermediate space.

Claims (6)

Patent claims: 1. Double-walled, thermally insulated container for low-boiling liquefied gases, consisting of an inner vessel and one of these at a distance to form an evacuated, heat-insulating one Space surrounding the outer casing, the outer casing being a 709 580/91 has upwardly directed neck part in which a neck tube connected to the inner vessel and closed at the top to form a steam chamber is concentrically arranged, the upper end of which protruding from the neck part and carrying means for discharging gas forms the outer part of the steam chamber, characterized in that that a throttle line (24) is connected to the outer part (17) of the steam chamber, which leads to a damping chamber (25), the throttle line (24) having an inner diameter of at least 1.6 mm and a ratio of length to inner diameter of has at least 52 and the ^{volume of the damping chamber (25), which is at least 5 cm 3} , is greater than the volume of the outer part (17) of the damping chamber and the inner length (α) of the damping chamber (25) is at least twice the inner diameter of the throttle line (24) ) amounts to. 2. Container according to claim 1, characterized in that the throttle line (25) has a has an inner diameter of 3.8 to 6.3 mm, that the ratio of the length of the throttle line to its diameter is between 100 and 400 and that the damping chamber (25) has a capacity of 20 to 2000 cm ³ . 3. Container according to claim 1 or 2, characterized by a wide-opening filler valve (36) for liquid, which is arranged on the outer part (17) of the damping chamber. 4. Container according to one of claims 1 to 3, characterized by a removable, sliding retractable liquid line (35) which is gas-tight through the outer part (17) of the steam chamber leads to the lower part of the inner vessel. 5. Container according to claims 3 and 4, characterized in that the liquid line (35) passes through the filler valve (36). 6. Device according to one of claims 1 to 5, characterized by a second damping chamber (31) and a second throttle line (30). Considered publications:
French patent specification No. 1243 988. 1 sheet of drawings 709 580/91 5.67 © Bundesdruckerei Berlin