EP0170142A2 - Safety device for vessels for storing low-boiling liquefied gases - Google Patents

Abstract

1. Safety insert for a vessel having an inner container (1) and an outer container (2) for the storing of low-boiling liquefied gases, the inner container being connected to the outer container by means of a tube forming the vessel neck (5), a discharge line (12) being attached to the vessel neck and a safety neck tube (8) with an opening for filling and removal and with a safety valve (10) being arranged concentrically in the vessel neck, forming an annular space (16) which serves the discharge of vaporized gas, characterized in that a helical flow channel is formed in the annular space and the helixes (17) have an increasing rise in flow direction, so that the vaporized gas has approximately a constant flow velocity.

Description

The invention relates to a safety insert for vessels for storing low-boiling liquefied gases according to the preamble of claim 1.

Vessels for storing low-boiling liquefied gases that have a neck-shaped opening for filling and removal, for example helium cans, are provided with a safety insert. This essentially consists of a safety neck tube, which is arranged in the neck of the vessel in such a way that an annular space is formed between the neck of the vessel and the neck of the security neck. The liquid is filled and removed through an opening in the safety neck tube. A safety valve is also attached to the safety neck tube. The annular space is connected to the exhaust pipe for the removal of vaporized gas The use of the safety neck tube prevents the filling and removal opening from becoming blocked by freezing out of water and carbon dioxide after air ingress.

The exhaust pipe is an annular space in which the gas column therein tends to form taconis vibrations when the exhaust valve is open and closed. These are mechanical-thermal vibrations of a gas column, which cause a strong evaporation of the liquid. DE-OS 2 042 869 and DE-PS 2 747 492 show, for example, safety inserts of the type described. DE-PS 2 747 492 shows a safety insert in which taconis vibrations can be avoided by the fact that the vaporized gas passes both through the neck tube and is also removed through the annulus. However, this principle cannot be applied universally.

The invention has for its object to provide a safety insert for vessels for storing low-boiling liquefied gases, in which the formation of taconis vibrations is prevented with certainty.

Starting from the prior art taken into account in the preamble of claim 1, this object is achieved according to the invention with the features specified in the characterizing part of claim 1.

Advantageous developments of the invention are specified in the subclaims.

The formation of a helical flow channel in the annular space disrupts the gas vibrations in the longitudinal direction of the neck of the vessel, which are usually caused by the heating of the gas and the associated volume expansion, and heat transport into the container is avoided.

When removing the exhaust gas is forced to make an additional circular movement around the neck tube. This extends the gas path and increases the gas velocity. This is very desirable so that the neck of the vessel is cooled intensively. For this reason, the annular space is also made very narrow in previous designs.

In the simplest case, the helical flow channel according to the invention can be formed by gluing corresponding coils, for example made of plastic, onto the neck tube. In one construction, 0.8 mm thick plastic straps were used. The neck tube can also be produced from the outset with such helices, for example as a blow molded part. In these embodiments, it is possible to increase the pitch of the spirals in the direction of flow. The cross section of the helical flow channel is thereby continuously enlarged in the direction of flow. In this way, the volume expansion of the continuously warming, flowing gas can be compensated so that the gas velocity remains at least approximately constant. It has been shown that the cold content of the outflowing gas can be used to advantage.

In another variant of the safety insert according to the invention, the neck tube is designed as a spiral corrugated tube, which is based on the neck of the vessel. Here, the pitch of the coils is constant, but the construction is considerably cheaper because the neck tube does not have to be constructed separately. Corrugated hoses are inexpensive finished parts, which also have a very small wall thickness. As a result, the heat conduction from the outside through the neck tube into the interior of the vessel is reduced. Furthermore, the heat conduction path is considerably lengthened and the free cross-section for the heat radiation in the container right induced. The proportion of diffuse radiation is also reduced.

Three embodiments of the invention will be explained with reference to the accompanying drawings.

• Fig. 1 ein Gefäß zur Aufbewahrung von flüssigem Helium mit einem Sicherheitseinsatz im Schnitt;
• Fig. 2 im Detail ein Sicherheitshalsrohr mit Wendeln unterschiedlicher Steigung;
• Fig. 3 ein als spiraliger Wellschlauch ausgebildetes Sicherheitshalsrohr.

Show it:

• 1 shows a vessel for the storage of liquid helium with a safety insert in section.
• 2 shows in detail a safety neck tube with coils of different pitch;
• 3 shows a safety neck tube designed as a spiral corrugated hose.

1 shows the upper part of a vessel for storing liquid helium 4 consisting of an inner container 1 and an outer container 2. An insulation 3 is located between the inner container 1 and the outer container 2. The vessel neck 5 leads from the inner container 1 to the outside and ends in a flange . The neck insert head 7 is connected to the flange 6. This contains the safety neck tube 8 and in its extension to the outside a lifting valve 9 for filling and removal. A safety valve 10 and a pressure gauge 11 are also connected to the extension of the safety neck tube 8. The end of the neck 5 is connected to the exhaust pipe 12, in which a safety valve 13, a shut-off valve 14 and a check valve 15 are arranged. The annular space 16 formed between the safety neck tube 8 and the vessel neck 5 is formed according to the invention by glued spirals 17 as a helical flow channel. This provides an effective resistance to the longitudinal out Spread of pressure waves, which are formed by increasing the volume when the gas is heated and which result in the Taconis vibrations. The helical flow channel increases the path of the exhaust gas and its speed, which cools the neck more intensely. This is an additional advantage of the security use according to the invention. FIG. 2 shows a detail of a neck 5 with a safety neck tube 8 and a spiral 17 glued on. In contrast to the embodiment according to FIG. 1, the spiral 17 has an increasing gradient in the direction of flow. The direction of flow is indicated by arrows 18. As a result, the increase in volume of the outflowing, heating gas is compensated so that an almost constant gas velocity is obtained.

Fig. 3 shows a variant in which the safety neck tube 8 is designed as a spiral corrugated hose 19 which bears directly on the neck 5 of the vessel. This variant is particularly inexpensive and also has a high resistance to heat which reaches the inside of the vessel from the outside through the safety neck tube 8. All that is required is that a corrugated hose with a very small wall thickness is used.

Claims (5)

1. Safety insert for vessels for storing low-boiling liquefied gases, consisting of a safety neck tube (8) arranged in the vessel neck (5) with the formation of an annular space (16). With an opening for filling and removal and with a safety valve (10) and with a Exhaust pipe (12) attached to the neck of the vessel, characterized by
Means for forming a helical flow channel in the annulus. 2. Security insert according to claim 1,
marked by
a helix (17) glued to the safety neck tube. 3. Security insert according to claim 1,
characterized,
that the safety neck tube is designed as a blow molding or injection molded part with an embossed spiral. 4. Security insert according to claim 1,
characterized,
that the safety neck tube (8) is designed as a spiral corrugated hose (19). 5. Safety insert according to one of claims 1 to 3, characterized in
that the coils have an increasing gradient in the direction of flow such that, taking into account the progressive heating of the gas flowing through the helical flow channel, the gas has at least approximately a constant flow rate.

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