US2944692A - Expansible container for lowtemperature fluid - Google Patents

Description

July 12, 1960 J. H. FARRELL 2,944,692

EXPANSIBLE CONTAINER FOR LOW-TEMPERATURE FLUID Filed March 2'7, 1958 FIG. 2

} uvvmrons James A! Farm BY A/exls Pasfu/mv ATTORNEYS Unite EXPANsmLa coNrArNER FOR LOW-,

James HQ; Farrell, Arlington, and Alexis Pastuhov, Harassignors, by mesne'jassignments, to (3011- vard, Mass, stock Liquid Methane Corporation, New York, N.Y., a corporation of Delaware Filed Mar. 27, 195$, S er.'No.72 4,443

- 9 Claims. (Cl. 220 -9) This invention relatesto storing and shipping liquefied gases at low' temperatures and'moreparticularly to the States Patent rounding the walls for support,

Patented mini 32, 1%80 7 2 weight and cost of the storage or'shipping tank. One way in which the tank may be made to meet these requirements is to make some portions'of the tank expansible. It is therefore an object of this invention to provide a tank, suitable for storing and shipping liquefied gases,

which maybe constructed of thin metal walls, thus resulting in lower construction costs.

It' is another object to provide receptacles, suitable for. storing and shipping liquefied gases, which can re main continuously in contact with insulating material sur- It is another object to provide an inner receptacle for storing, and shipping liquefied gases which depends for a portion of its structural, support upon an outside receptacle.

It is a furtherobject of this invention to provide re- 1 ceptacles, suitable for storing and shipping liquefied gases,

cient of thermal expansion and hence is subject to -contraction and expansion when exposed to temperature 1 changes. The problem of expansion and contraction becomes markedly acute at the temperatures normally encountered in thehandling of liquefied gases because the temperature differential between the liquefied gas temperature and normal room temperature is very great.

In the case where the inside tank designed for storing or shipping liquefied gases is completely surrounded by 1 an insulating material, such as balsa or cellular glass for example,'contraction of the tank walls when the liquefied gas is added means that the walls pull away from the insulating material leaving a void area between the outside wall of the tank and the insulation material. There are cases where it is desirable to design the inside tank, containing the liquefied gases, so that itiwill depend for support upon the layer of insulation material and the outside wall of the receptacle surrounding the insulation material. When this'is desirable, it may readily be seen that gaps between the walls of the inside tank and the insulating material would lead to stresses in the tank walls brought about by the removal of the needed structural support otherwise ofiered by the outside receptacle and the insulation material andby the pressure of the liquid and/or of the gas within the inner tank. Repetition of the cooling-warming cycle, brought about by the addition and removal of the liquefied gas, and hence the stresses set upafter a relatively short period, may cause 'the inner tank to fail. This is particularly true when the inner tank isintentionally fabricatedot thin gauge metal which is incapable by itselt of maintaining shape under the liquid and/ or pressure load.

. Moreover, if the inner tank containing the liquefied gas is only partially. filled a large temperature gradient will existin the gas column above .the liquid level. -T his means that the tank wallswill also exhibit-a marked temperature gradient approximating the temperature gradient in the gas because of the very low thermal conductivity of metal walls at the low temperatures involved. The resulting temperature gradients introduce additional stresses in the walls which may be partially relieved by the tank design of this invention.

It therefore becomesevident that it would be desirable to have metal storage tanks which have relatively thin metal walls and which can depend upon the outside receptacle for structural support, thus reducing the which are expansible under the hydrostatic load and/or under the pressure built up within the receptacle by the vaporization of the liquid into gas.

These and other objects will appear in the following discussion which is presented with reference to, the accompanying drawing in which Fig. 1 represents a cross-sectional view of the type of tank construction to which this invention is applicable; Fig. 2 is a diagrammatical View of four walls of the expansible tank of this invention, and r Fig. 3 is a detail drawing of the welding'of the expansible members.

'By the process of this invention, atank suitable for storage and transportation of liquefied gases is made expansible to allow the sides of the tank to remain substantially continuously in contact with the insulation layer and hence makefuller use of the additional'structural support oiiered by the insulation layer and/or the outside receptacle. The tank is made expansible by the con struction of the tank of prismatic shape with a corner portion in the form of a stapped member, hereinafter identified as a bellows type arrangement, joining the vertical walls, and by providing a stiffening or reinforcing member in the base portion of the bellows to pre vent collapse, particularly when formed of a highly resilient and deformable material. The bellows construction employed to join the side walls of the tank and to form the corner portions therebetween may also be employed in the top and bottom Walls to permit the corresponding type of expansion and contraction without the development of stresses otherwise occasioned by the movements which would take place in the side Walls. The rectangular'bellows permit each of the walls and the roof and bottom wall to move in a direction normal to its own plane when it is subjected to a slight pressure by the gas or liquid contained within the tank to compensate for the change in dimension upon expansion or con.- traction of the metal thereby to enable the walls to remain substantially continuously incontact with the layer of insulation for support.

The expansible tank of this invention may be further explained with reference to the figures.

In Fig. 1 there is shown a simplified cross-sectional view of the general type of tankusedfor storing or ship ping liquefied gases. The tank will be a polyhedron configuration and preferably one *which is a rectangular parallelepiped. The inner tank 10, designed to contain.

the liquefied gas 13, is placed within a surrounding vessel 11 and insulating'rnaterial lz placed between them.

Such a tank may be equipped with a filling line 22 in which is placed a pressure-regulatingvalve 21 to provide proper gas venting, and with a draw-off line 19 incorporating valve 20. When the sides, top and bottom of tank 10 press closely on the insulating material, tank 10 forms an integral unit with tank 11 and tank may therefore be of a lighter weight, thinner construction than if this integration did not exist. When the walls of tank 10 are cooled by the introduction of the liquefied gas, theycontract, 'if made in the conventional manner, and. ,pull away from'the insulation and destroy the necessary'integration and interaction.

'In a tank such as shown in Fig. 1 the surrounding vessel 11 may be eliminated where insulation 12is of such structural material, 'forexamp'le, cellular glass, cork orbalsa wood, that it forms a strong outside receptacle.-

In such a case bymaintaining the tank walls 10 in contact with'insulating material '1'2,"a strong integral unit is achieved without the additional tank 11.

In Fig. 2 it is shown how four walls of the inside tank 10 which "actually contain the liquefied gas are made expansiblelin accordance withthe practice of this invention. The tank of'Fig. 2"has a rigid frame 17 made of stiffening members. Tank wall 16 is connected to the tank frame'17 by. meansof rectangular bellows 18 which are welded or otherwise joined at their lines of contact-with frame 17. Sufiicient freedom of movement is provided by the convolutions of the bellows to permit wall 16 to move back and forth from its corresponding frame member 17 in a direction normal to the plane of the wall. In similar fashion the top of the tank may also be connected by means-of bellows. It is not necessary to equip the bottom of the tank with an expansible wall since the weight of the liquid contained will be sufficient to keep the bottom tightly pressed against its insulation. Furthermore, the bellows, if they are used on the bottom wall, would normally always be contracted.

Fig. 3 illustrates in detail an example of a rigid member and the way in which the bellows 18 may be joined to this member 17 and tank wall 16. Other .forms of rigid members, such as ,I beams, may be used equally well.

The components, including walls, stiffening members and bellows, of the tank of this invention are conveniently constructed from stainless steel. However, other suitable metals, such as aluminum or'alloys, which possess the desired structural strength, may be used.

The numberof bellows, their size and thickness of bellows materials will be determined by the design conditions set for the system. 'In general, the number of bellows is anfunctionof the thickness of bellows material, the pressures at-which they must work, the extension ofthe walls required and upon the stresses involved, the higher the stresses thefewer bellows required. As an example of the number of bellows which may beused, assume a tank which is 33.,feet by 28 feet at the base and 50 feet high. In such a tank, if the bellows material is 0.05 inchthick, a bellows with 44 convolutions would be considered advisable vwhile if the bellows material is 0.125 inch thick, some .18 .convolutions are .desirable.

The size of-the tanks to which the expansible sides of this .invention are applicable will vary with design-conditions, .particularly with the internal .pressure the tank. .That is, the. .higher the internal pressure, .the smaller the tank should be to prevent racking of the bellows. The .extensionofthe bellows is alsodependent upon the size of the tank. .The larger the tank, the greater extension required.

The bellows may be formed by anysuitable means such as by weldingsections together along their longitudinal .edges or by folding the convolutions to shape. The bellows .are'then preferably welded to the supporting means and the tank walls .to form the completed tank which is hermetically =sealed to contain the liquefied gas.

The supporting or stilfeningmember -17 may comprise an elongate :membenofrectangular shape, as shown, but it may equallycompriseen elongate member of baror polygonal shape. In the preferred iembodil'flfillt, the stiffening member is arranged with one-of its; fiat sides in abutting relationship with the flat face innermost in the corner construction embodying the expansible bellows. It will be apparent that the stifiening member can also be fixed to the bellows portion along one of the edges or corner portions of the stiffening member, as shown in Fig. 4, thereby to provide for still greater resiliency or deformation in the wall construction without sacrifice of rigidity or support. It is preferred to embody the bellows as a corner of the polyhedron but it will be apparent that the'bellows can beincorporated into a wall-portion :intermediate its ends, as illustrated 'in thetop wall in Fig. 3. While it can extend outwardlyfrom the top wall, it would be apparent that in the'side and bottom walls of the tank the bellows would extend inwardly into the tank.

Thus, by the use of the expansible tanks of this invention, there are provided meansfor continuously keeping the outside of the tank walls in contact with the insulating material surrounding the tank which in turn means that thin-walled tanksmay be used since the tank can..be structurally supported by the insulation and the outside tank or by the insulation alone.

We claim: a V

1. A tank for the storage of aliquid, theflboiling point of which diflers widely from the ambient temperature, consisting of an inner shell housing said liquid and which is subject to noticeable expansion and contraction due to temperature changes, a thermal insulating material surrounding the inner shell, said inner shell'having the shape of a polyhedron and being provided with an expansible member at each of a plurality of the edges of the sides of said polyhedron, each such expansible member being in the form of a bellows member, each such bellows member being hermeticallysealed along one edge to the contiguous edge of the side which it joins, a rigid member disposedparall'el to said contiguous edge and secured thereto, the rigid members of said edges of said polyhedron constituting a supporting frame for-saidpolyhedron, whereby the inner shell remains continuously substantially in contact with theinsul-ating material.

2. A tank according to claim '1 wherein said inner shell is coated with a-thermal'insulating'material'having structural strength.

3. A tank according to claim 1 wherein an outershe'll surrounds and'remains continuouslyin contact with the insulating material.

4. A tank according'toclaim 1 whereinsaid inner shell is a rectangular parallelepiped.

'5. A tank according to claim 1 wherein all of the edges of the sides of said inner shell are provided with said expansible member.

6. A tank according to'claiml wherein a frame defines the shape of said inner shell, said frame comprising a plurality of straight rigid members and supporting the side of said inner shell, each of a plurality of the edges of said sides being'hermetically'joined to "said-frame by means of a bellows member. 7

7. A tank according to claim 1 wherein-saidbellows members extend outwardly from the inner 'shell.

.8. A tank according to claim l-wherein'said bellows membersextend inwardly into the inner shell.

9. A tank of largecapacity' 'for the sto-rage'of a liquefied natural gas at about atmospheric pressure consisting of an inner shell-formed of metal capable of retaining its ductility -atthe low temperatureof the liquefield 1 gas and which is subject tochange'in'dimensionsdue to expansion and contractionin-response-to temperature change, an outer shell surrounding the inner shell in-spaced relation'therewith to provide an open space'in-between filled with thermal insulating material, said inner shell having the shape of a polyhedron which'is formed of thin-metal walls, an expansible member :at each of a plurality of the edges ofthe sides of saidpolyhedron, eachssuch :expansiblemember being in .the form. of abellowsymember, each such-bellows member extending .inwardlyzinto the inner shell-and beinghermetically sealed alongiits' sedges r 5 to the contiguous edges of the side adjacent thereto to interconnect the adjacent sides in sealing relationship therebetween, a rigid member disposed parallel to said contiguous edge and secured thereto, the rigid members of said edges of said polyhedron constituting a supporting I frame for said polyhedron, whereby the inner shell remains continuously substantially in contact with the in- References Cited in the fileof this patent UNITED STATES PATENTS Moore May 10, 1892 Ziebold June 25, 1957

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