DE1815242A1 - Storage tank for gas liquefied at low temperature - Google Patents

Description

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BRIDGESTONE IiIQuElIED PETROLEUM GAS COMPANY LIMITED, No. 2,1-chome, Kyobashi, Chuo-Ku, Tokyo, Japan

Storage tank for gas liquefied at low temperatures

The invention relates to tanks for storing or storing gas that is liquefied at low temperatures, such as low-temperature gas liquefied natural gas, low-temperature liquefied Petroleum gas, etc. and in particular an improved thin film tank type,

A thin-film tank consists of an outer container with a rigid solid construction, a heat-insulating layer which has a suitable pressure resistance and is provided on the inner side of the outer container, and an inner container with a construction of a thin film which is is located within the heat insulating layer, the inner container only ensuring to prevent leakage of the liquefied gas, and in which the weight or load of the liquefied gas is caught by the heat insulating layer and carried by the fast outer container, such an inner container comes into contact with the liquefied Cfaa at a low temperature; so that it bound disgust from a g g ° ^ low temperatures inept material must be prepared day expensive Lato Ba, however, the inner Dicks clss. .Behältern baä.w, cisaaan v / anduug klein iat, this can be in a cheaper V / eise hergea ball., *

BATH ORIGINAL

However, the inner container of the thin-film tank does not only contract when it is liquefied at the lower temperature Gas is exposed, but is stretched as well when it is subjected to the load generated by the cryogenic liquefied Gas originates, and when it is brought into close abutment or contact with the heat insulating layer. In this case, it is not desirable that the elongation of the inner container beyond the elastic limit of the Material goes out. To avoid such overstretching, a mechanism can be provided to prevent it from being stretched and allow the inner container to contract. However, this mechanism has the disadvantage with it that the construction of the inner container is difficult and expensive, moreover, the inner Container made of the thin film does not maintain its shape and therefore has to be different Points are held by the heat insulating layer. These holder points are intended to allow free movement of the interior Prevent container, with the result that dangerous voltages arise inside.

It is an essential object of the present invention to provide a better thin film tank and in particular an inner container of this tank which does not have the disadvantages outlined above.

Other advantages and details of the invention emerge from the description of exemplary embodiments which follows having · referring to the drawings, In this shows?

PIg ₃ 1 a longitudinal division of a tank

to save or. Storage of low temperature asi liquefied gas. according to the present invention ι

109824/0520

fi§; 2 a representation of the social class , -. . the ^ direction lh Pig; i |

P'ig; 3 is a representation of the scHekätisÜiife ffecnseibezifeiiühg zwisc & eh the dimensions of an inner holding rs ¹ and the dimensions feiiifes äüssei-eii ÖIHälters |

figi i feiii'e ^: Queföbiiiiit-fcs-S "ciiiiiitääi? sieilüiig züi? Verahsblmüliclmiig" dfer Wiriniiigswbise dfeis tanks iikch "d'ei · j? ig; 1}

B ¹ Ig ;; 5 is an enlarged view of a part (H deir in Pig. 4 is indicated by dash-dotted lines , and

Pig. Bit - 6D increase DärsteÜüngehj by the

different layers üiid mode of action of the inner seer 2U veriahshell, the one from a slightly ruffled chamber of the present invention.

In Fig; ί with 1 is a cover plate of an outer container denotes, 2 "denotes a side wall and 3 a floor panel this container. Denoted at 4 is a heat insulating layer which has a suitable pressure resistance has, with 5 a top plate of an inner container, and 6 denotes the side wall and 7 a bottom plate this inner container.

In accordance with the present invention, the inner container is made from a thin sheet of material and is constructed to support the weight or the load of the oil liquefied at low temperature, that was filled in the inner container, from the heat insulating Layer 4 is collected and transferred to the outer container. The one shown in the drawing

"" - nrfWÄ7T5TÖ ~~~ ÖAO ORfQtNAi

Embodiment shows an inner container of one thin film and is constructed so that it is attached to its cover plate 5 ", namely to the outer container, including the heat-insulating layer 4, while the remaining parts of the inner container are not attached to the outer container are attached.

The inner container is then deformed in this way if it can withstand the weight of the low-temperature liquefied gas is exposed. This deformation of the inner container takes place due to a so-called membrane force, which propagates through the thin ^ iIm. In a longitudinal section plane through the inner container, the membrane force moves against this part of the inner container, which is in less is exposed to a large extent to the weight resulting from the low-temperature liquefied gas. As a result the deformations concentrate on a shoulder section of the cover plate 5 »where no liquid weight acts, and the membrane force acting on the inner container acts in its longitudinal direction, dissolves or disappears. In a horizontal sectional plane of the inner container However, the weight resulting from the low-temperature liquefied gas is evenly distributed and thus they make themselves uniform and uniform

a
Ring forces /. These ring forces, which act on the inner container in the horizontal direction, will now be described below.

If the dimensions of the inner container at room temperature are made equal to the dimensions of the outer container, the inner container contracts when it is submerged Liquefied gas is exposed, while the outer container is exposed to the low-temperature liquefied gas is not exposed, so that it is not deformed

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BATH

which creates a gap between the inner and outer container. This creates the inner container Exposed to tensile stresses resulting from the singing forces (hoop force).

In general, when a thin I ¹ um made of metals such as steel, aluminum, etc. is used as a construction material for the inner container, the inner container must extend beyond its. Extend the elastic limit so that the gap that results when the material is demolished is closed. is exposed to low-temperature liquefied gas that has a temperature of less than approx. -40 ° C »."

In this way there is in the above-mentioned design that if the dimensions of the inner container at Eaumtemperatur be chosen equal to the dimensions of the outer container, considerable constructive disadvantages _y set, ie, that the inner container has an inside

corresponding
Generates tension that is / above the elastic limit.

In the case of the present tank, the dimensions of the inner container at room temperature greater than the dimensions of the outer container chosen to counter the above disadvantage.

Basically, the inner tank, which consists of the thin-film tank, should have the shape of a liquid-tight bag exhibit. It is desirable that in such a liquid-tight pouch does not result in tension, even if this is exposed to the weight of low-temperature liquefied gas.

In Figure 3 is the correlation between the dimensions the inner container and the dimensions, the outer loading -—- - - ^^^ - ^ - ^ - ^ - ^^ _

8ADOWGfNAL

holder illustrates when F denotes a point where no tension is exerted, and it can be establish the following relationship by the following equation:

In here is

(V) the dimensions of the inner container at room temperature, which are designed so that no tension is exerted on them when the container can bear the weight of the cryogenic exposed to liquefied gas,

(2) the dimensions of the outer container,

(3) the thermal contraction distance of the inner container, and

(4) the degree of deformation or the distance of the outer container when this liquefied under the load of the cryogenic Gas is exposed.

The dimensions and dimensions of the interior are required The container should be larger than that of the outer container, with the degree of contraction of the inner container and the degree of deformation of the outer container when exposed to the weight of the cryogenic liquefied gas, in practice it is it, however, mostly impossible to match the dimensions of the inner and outer container and although at the point without tension mentioned above]? due to the constructive training and working accuracy ^ different types of hoop force occur, depending on the dimensions of the

_ __ 1 ü 3 WlTi 0 5 2 0 ~ "

inner container smaller or larger than the mass accordingly the spaniutfigslos point lj / ΓThe following results :

1. There are tensile stresses on the inner container act if its dimensions are smaller than the dimensions corresponding to the stress-free point F,

2. There are compressive stresses on the inner container act when its dimensions are slightly larger than the dimensions corresponding to the stress-free point F, and

3 * there are compressive bending stresses that act on the inner container if its dimensions are considerable are larger than the corresponding of the 'dead point F.

If tensile stresses and compressive stresses act on the inner container, as is the case in the aforementioned cases 1 and 2, the permissible material stress is about 0.2 io of the shape of the inner container within the elastic limit, that of steel, aluminum etc. is made. When this material stress greater than about 0.2 ° is o /, 'occurs a plastic deformation of the inner container. In order to avoid such plastic deformation of the inner container, it is necessary to make the accuracy of the structural design and the machining better than 0.2 fo . However, as previously mentioned, it is extremely difficult to carry out the execution and machining with an accuracy of better than $ 0.2. '

109824/0520 _B AD ORIGINAL

When generally the inner container made of thin elm is a welded one Has construction, the film must have a considerable thickness and thus has a certain flexural rigidity. Therefore, if the size of the inner container is considerably larger than that of the dead point F corresponding to it are chosen as previously mentioned under case 3, then the protruding part or the protruding part is of the inner container, which is larger than the dimensions at point F without tension, is bent or wavy and forms uniform Waves, as shown in Figures 4 and 5, when the inner container is liquefied at the cryogenic temperature Gas is exposed.

The shape and number of these waves are determined by the size of the inner container, the size of the protrusion of the inner one Container larger than that of the stress-free point F, the elastic modulus of the film, the thickness of the film, the modulus of elasticity of the heat-insulating layer is determined, the latter layer suitably the inner container and the weight of the low temperature liquefied Gas absorbs.

The number of these waves changes depending on the weight of the low-temperature liquefied gas. If those As the load increases, each of these waves becomes smaller and the number of waves thus increases.

The load acting on these shafts presses on a curved shaft that has a length L and at both ends J and K of each wave experience a back pressure as shown in FIG.

TO 9 8 2 4/0 5 2 0

In this way the 'weight of the cryogenic is liquefied Gas absorbed by the curved shaft, so that the permissible protruding length of the inner container, which is larger than the corresponding dimensions at the de-energized Point I ^ of resistance or strength (strenght) depends on the curved wave. The degree of excess length of the inner container depends on those mentioned above different conditions and is correspondingly greater than the permissible material tension of the inner container designed to occur when the inner container is subjected to tensile stresses and compressive stresses, as noted below to the aforementioned cases 1 and 2 has been described. In particular, if the supporting points J and K are on a elastic, heat-insulating shoes that have a comparatively small modulus of elasticity (young modulus), the compressive bending stresses or buckling stresses are relatively small.

A tank, for example, having an inner diameter of 20 m and in which there is an inner container made of aluminum film, the thickness of which is 3 mm and this inner container is supported by a solid, stiff heat-insulating layer, is given as an example. The permissible ratio of the length excess of the inner container is approximately 0.6 ° / o of the inner container made of aluminum film for a design or structural configuration within the .Elastizitätsgrenze when this film is subjected to the weight of tieftemperiertem liquefied gas, with a Druokwert of 0.6 kg / om. ·

With other words, the permissible material voltage is for case 3 approx. 3 times that for cases 1 and 2.

109524/0520

BAD OWlGtNAL

- ίο -

As you can see from the foregoing, so it is it is preferable to choose the dimensions of the inner container slightly larger than the corresponding dimensions of the de-energized one Point F.

When the inner container is placed in the outer container at room temperature, even in case 1 the Dimensions of the inner container selected larger than those of the outer container, so that in cases 2 and the dimensions of the inner container can be chosen to be considerably larger than the dimensions of the outer container.

The portion of the inner container that is larger than the outer container or protrudes beyond it must be in the outer container are added as corrugations and these corrugations should disappear when the inner Containers of low temperature and load and weight exposed to the low-temperature liquefied gas. Conventional flexible couplings cannot to be used for the purpose of achieving such a result and object as if one had these corrugations used. It is preferable that these corrugations are evenly distributed and resiliently adjust themselves and indeed to their primeval form, when the load Will get removed.

Experimental trials have shown that the aforementioned Requirements can be satisfied by using chambers 6 that are slightly corrugated, as shown in FIG.

Figure 6A shows the interrelationship between the inner and outer containers in which the bottom of each chamber

is in contact with the outer container, while the ceiling of each chamber 6 is located within the outer container. When the inner container is exposed to the cryogenic liquefied gas, the inner container contracts and moves inward and lifts off from the outer container, as shown in FIG. 6B. At the same time, when the inner container is subjected to the stress due to the cryogenic liquefied gas, the inner container is pressed against the outer container, whereby the chambers β disappear and come to the above-mentioned stress-free point F, as shown in FIG. If the dimensions of the inner container are considerably larger than those of the no-tension point F, then the excess portion of the inner container that is larger than the dimensions of the no-tension point F is folded into a number of corrugations, as in Figure 6D shown. The shape of these waves does not depend on the chambers shown in Figure 6A, but is determined by the various conditions mentioned above.

While the invention has been described in terms of a vertical cylindrical thin film tank, it is understood that that the invention is also used in rectangular thin-film tanks in a boat hull or the like can be. In addition, the invention has been described in terms of an inner container that is not load-bearing Places in the horizontal sections of the container, and the invention can also be used for rectangular tanks can be used, which are each equipped in their toe with a partition to which the inner container is attached. Therefore, the invention is not to the ' Shape of a tank and the presence or absence of bearing points or of fastening points

1098 2 4/0520

inner Tanks in - 12 - Sections 1815242 > addicted. horizontal of

j All recognizable in the description and in the drawing! Details shown are relevant to the invention significant.

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Claims (3)

Storage tank for "at -Yi-
Patent claims 1815242 low temperatures - 1. liquefied gas, characterized by the combination of a outer container with a solid, rigid construction, to which a heat-insulating layer (4) adjoins on the inside, and this heat insulating layer is suitably pressure resistant, an inner container in a thin film construction, which is provided in the outer container, the inner container has external dimensions, which are relatively larger than the inner dimensions of the outer container, thereby reducing the membrane material stresses that arise on the inner container act when it is exposed to the load from the low-temperature liquefied gas, im can be reduced to substantially zero and the compressive bending stresses are also substantially eliminated. 2. Device according to claim 1, characterized in that that the inner container has slightly corrugated corrugated chambers (6) which disappear when the inner container of Stress is exposed to the cryogenic liquefied gas, causing the membrane material stresses or dia Compression bending stresses acting on the inner container can be reduced to essentially zero. 3. Device according to claim 1, characterized in that that the heat-insulating layer has a comparatively small modulus of elasticity, whereby the pressure bending stresses are reducible » 4 * device according to claim 1, characterized in that that the inner container has a cover plate (5), and that the deformation of the inner container in the plane a 109824/05 2 0 vertical section through the inner container, are intercepted by shoulder sections of this cover plate (5), this deformation takes place when the inner container is exposed to the load by the low-temperature liquefied gas is exposed. 109824/05 20