US3362559A

US3362559A - Fluid storage tanks

Info

Publication number: US3362559A
Application number: US409547A
Authority: US
Inventors: Kohring Walter
Original assignee: Individual
Current assignee: Individual
Priority date: 1963-11-08
Filing date: 1964-11-06
Publication date: 1968-01-09
Anticipated expiration: 1985-01-09

Description

Jan. 9, 1968 w. KOHRING 3,362,559

FLUID STORAGE TANKS Filed Nov. 6, 1964 2 Sheets-Sheet 1 Fig.1.

: I INVENTOK 2 )Valtiua) BY \aimbcow loczs ATTORNEY Jan. 9, 1968 w. KOHRING FLUID STORAGE TANKS 2 Sheets-Sheet 2 Filed Nov. 6, 1964 I VENTOl-Z BY 59-h ATTORNEY United States Patent ice 3,362,559

3,362,559 FLUID STORAGE TANKS Walter Kohring, Garwood Cottage, Church Road, Rawreth, near Wickford, Essex, England Filed Nov. 6, 1964, Ser. No. 409,547 12 Claims. (Cl. 220-9) This invention relates to a fluid storage tank and is particularly although not exclusively applicable to a tank for the cryogenic storage of liquefied gases. The invention also relates to a method of heat insulating such a tank.

Such tanks are often of very large size and are double walled having an inner storage vessel located within an outer casing the space between the vessel and the casing containing heat insulating material. The tanks are frequently of cylindrical shape either square or circular in cross section about a vertical axis and are supported on a flat base.

The heat insulating material usually preferred comprises loose particles which may be of irregular shape and size such as for example a mica-based substance; it may be in the form of a powder or it may be in the form of hollow substantially spherical particles. In all these cases however the particles in known manner provide a multiplicity of pockets so that gas trapped therein acts as the effective heat insulating medium.

With the bulk storage of liquid gases at cryogenic temperatures the inner storage vessel is from time to time subjected to very large temperature changes (of the order of 300 C.) and with a vessel of large size (for example in excess of 100 ft. diameter) radial movement of its walls can be of the order of 4 to 6 inches. Since the outer casing remains stationary during any such expansion and contraction of the inner vessel the heat insulating material is subject to considerable compression on expansion of the storage vessel and although some expansion of the material may occur on contraction of the vessel trouble is experienced in the formation of voids generally alongside the wall of the vessel.

Although most insulating materials of the type described above tend to flow freely in the uncompressed state compression causes them to cake. Upon contraction of the inner vessel support is removed from the inner surface of the caked material and the weight of the latter causes lines of cleavage to occur apparently haphazardly therethrough so that the material tends to settle towards the base of the tank some of it reverting to a flowable state but some of it remaining in a caked condition. Thus a multiplicity of voids some of considerable size are left between the inner vessel and the outer casing and the overall level of the material will need to be topped-up. Thus the heat insulation of the inner vessel will be seriously impaired.

In addition and depending upon the nature of the insulating material expansion of the inner vessel could cause large and undesirable pressures to be transmitted to the outer casing which is not intended to withstand excessive localised internal pressure.

It is an object of the present invention to provide an improved construction of fluid storage tank and a method of heat insulating such a tank. Particularly although not exclusively it is an object to provide an improved storage tank for the cryogenic storage of liquefied gases which permits particulate heat insulating material to be used between the inner vessel and the outer casing while reducing the disadvantages set forth above,

According to one aspect of the invention a method of heat insulating a fluid storage tank includes locating around at least part of the tank in spaced relationship thereto a framework which in vertical section comprises a number of vertically spaced apart members and dis- Patented Jan. 9, 1968 posing particulate heat insulating material between the framework and the vessel so that the material is constrained by the member.

According to another aspect of the invention a method of heat insulating a fluid storage tank comprises constraining a quantity of particulate heat insulation material around the tank by a framework which in vertical section comprises a number of vertically spaced apart members arranged so that the material adopts its natural angle of repose between each member and the next lower member.

Another aspect of the invention provides a fluid storage tank comprising an inner storage vessel and a framework located outwardly of and spaced from the vessel the framework comprising in vertical section a number of vertically spaced apart members arranged so that particulate heat insulating material disposed between the vessel and the framework is constrained by the latter.

Yet another aspect of the invention provides a fluid storage tank comprising an inner storage vessel and framework located outwardly of and spaced from the vessel the framework comprising in vertical section a number of vertically spaced apart members arranged so that particulate heat insulating material disposed between the vessel and the framework falls freely at its natural angle of repose between each member and the next lower member.

Several embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which:

FIG. lshows in axial section the lower part of a cryogenic storage tank according to the invention,

FIG. 2 is an elevational view of part of a framework,

FIG. 3 shows diagrammatically an elevational view partly in section of a modified construction,

FIG. 4 is a section on the line IVIV of FIG. 3,

FIG. 5 is a fragmentary perspective view of part of the construction of FIG. 3,

FIG. 6 is a diagrammatic view in vertical section of another arrangement and FIG. 7 is a diagrammatic plan view of another arrangement.

Referring to FIG. 1 of the drawings this shows a modification of a construction fully described in the specification of co-pending application Ser. No. 253,584, now abandoned comprising an inner storage vessel 1 mounted upon a concrete base 2 and located by long bolts 3 extending through sockets 4 into the ground 5 beneath the base 2. An outer casing 6 is provided in spaced relationship to the vessel 1 and in the previous arrangement it is assumed that the annular space therebetween is filled with particulate heat insulating material.

In the arrangement of the present invention a framework indicated generally at 7 is disposed between the wall of the vessel 1 and the wall of the outer casing 6 and in vertical section as shown comprises a number of vertically spaced inwardly and downwardly inclined lamellae 8 secured to a supporting structure which includes a number of struts 9 joining the outermost parts of the lamellae and as shown in FIG. 2 extending at an acute angle to the vertical. It will be understood that additional supporting struts than those shown may be employed if required and that the framework is supported by the base 2.

The lamellae 8 comprise discrete annuli of circular or polygonal shape in plan.

As shown in FIG. 1 particulate heat insulation material 10 is disposed between the vessel 1 and the framework 7 the lamellae 8 being so vertically spaced apart and extending radially of the vessel 1 by such a distance that the material It) falls naturally as shown at 11 at its natural angle of repose between one lamellae and the next lowermost lamella.

It will be understood that when the vessel 1 expands the lamellae 8 tends to introduce lines of cleavage into the bulk of the material 10 causing the latter to ride up the upper surfaces of the lamellae and depending upon the extent of expansion of the material some of it may spill and fall into the space 12 between the framework 7 and the outer casing 6. In this respect the struts 9 constitute spillage conductors tending to guide the overflow into specific circumferential locations around the framework. It will be appreciated that with this arrangement the space 12 can constitute a walkway with suitable access (not shown) provided in the casing 6 to permit periodic inspection and ready removal of the spillage.

Although in the preferred form the upper surfaces of the lamellae 8 are inclined downwardly and inwardly towards the vessel 1 so that at least to some extent when contraction of the vessel occurs after expansion thereof some of the material 10 will slide back down the lamellae to occupy the position shown in FIG. 1 these lamellae could be constituted by members of different shape and indeed their upper surfaces could be at different inclinations from that shown. The upper surfaces could for example be horizontal or it would be possible to have a small reverse slope so long as this was less than the angle of repose of the material and the radial dimension of the surface was suflicient to accommodate the necessary free fall 11 between successive lamellae. In addition the upper surfaces of the members could be curved.

FIG. 3 is of the drawings shows a modified arrangement in which a single helical strip 8a is disposed around the inner storage vessel 1 in vertically spaced apart turns to provide the lamellae 8. The turns are held in place by a number of circumferentially spaced vertically extending supports 9a which are secured at their lower ends to the base 2 by bolts (not shown) and are disposed inwardly of the strip 8a. The supports are generally cusp shaped in horizontal section having two arms and 90 formed with inclined slots such as 9d to receive the lamellae 8. The arrangement of the supports 9a is shown more clearly in FIGS. 4 and 5.

It will be understood that with this arrangement the strip 8a could, for transport purposes prior to assembly, be wound into a coil of such smaller diameter than required in the assembled installation.

FIG. 6 shows diagrammatically an arrangement which can be used with the constructions of FIG. 1 and FIG. 3 whereby the upper part of the framework '7 terminates short of the upper part of the outer casing 6 and the latter is formed at its upper extremity with an open hopper 13 having an inclination greater than the natural angle of repose of the material 10 the latter extending from the upper part of the framework into this hopper and the space 12 being connected at a number of locations over fluidised pipelines 14 so that spillage can be returned to the hopper 13. In a further modification not shown in the drawing, the space 12 is connected via suitable channels to a storage chamber located centrally below the tank so that a single fluidised connection therefrom may be used to return the spillage of the material 10 to the hopper 13.

FIG. 7 of the drawings shows diagrammatically in plan with the upper part cut away another arrangement in which a symmetrical arrangement of cylindrical tanks 1 each surrounded by a framework 7 (which may be in accordance with FIGS. 1 and 2 or FIGS. 3 to is disposed within a single outer casing 6.

It will be understood that with this arrangement as indeed with the arrangements of FIGS. 1 and 3, it is possible to have the outer casing 6 of lightweight construction to constitute merely a weatherproof enclosure since it is not subjected to any stresses as a result of expansion and contraction of the storage vessel or vessels themselves. For example, it would be possible for the outer casing 6 to be of lightweight plastic sheet material.

Although in the examples described above it is assumed that the storage tanks are very large it will be understood that it is possible to utilise the heat insulation arrangement of the present invention for smaller structures and for example several tanks together with their associated framework 7 could be accommodated in an existing building.

It will further be understood that although the tanks described above are of cylindrical form having a circular cross-sectional shape, they could be cylindrical but of other cross-sectional shape or they could be spherical or part-spherical.

I claim:

1. A fluid storage tank comprising a storage wheel, a framework located outwardly of and spaced from the vessel, said framework comprising in vertical section a number of vertically spaced annular radially inwardly and downwardly sloping members, particulate heat insulating material disposed between the vessel and the framework, the exterior face of said material extending at the natural angle of repose thereof respectively between each member, an outer casing surrounding and spaced from the framework, a hopper at the upper extremity of the outer casing at least one wall of the hopper having an inclination greater than the natural angle of repose of the material the said material extending from the upper part of the framework into the hopper and means for moving any of said material spilled into the lower part of the space between the framework and the outer casing to the hopper.

2. A fluid storage tank according to claim 1 in which said means comprises pipelines connected between a number of locations in said space and the hopper.

3. A fluid storage tank according to claim 1 comprising a chamber beneath the vessel, channels connecting said space to the chamber and a pipeline connected between the chamber and the hopper.

4. A fluid storage tank installation comprising a plurality of tanks according to claim 1 disposed within a single outer casing.

5. A fluid storage tank comprising a storage vessel, an outer casing spaced from the vessel, a framework located between the vessel and the outer casing and spaced both from the vessel and the outer casing said framework comprising, in vertical section, a number of vertically spaced apart substantially horizontally extending members, particulate heat insulating material disposed between the ves sel and the framework, the outer face of said material extending at the natural angle of repose thereof respectively between each member and the next lower member, the material being constrained against the vessel and out of contact with the outer casing,

6. A fluid storage tank according to claim 5 in which the members comprise discrete annular lamellae extending in generally horizontal planes.

7. A fluid storage tank according to claim 5 in which the members comprise individual turns of a single helical strip.

8. A fluid storage tank installation comprising a plurality of tanks according to claim 5 disposed within a single outer casing.

9. A fluid storage tank comprising a storage vessel, an outer casing spaced from the vessel a framework located between the vessel and the outer casing and spaced both from the vessel and the outer casing said framework comprising, in vertical section, a number of vertically spaced apart members, upper surfaces of said members which are inclined downwardly towards the vessel, particulate heat insulating material disposed between the vessel and the framework separate faces of said material extending at the natural angle of repose thereof respectively between each member and the upper surface of the next lower member the material being constrained against the vessel and out of contact with the outer casing.

10. A fluid storage tank comprising a storage vessel, an outer casing spaced from the vessel, a framework located between the vessel and the outer casing and spaced both from the vessel and the outer casing, said framework comprising in vertical section a number of generally horizontally extending vertically spaced apart discrete annular lamellae inclined downwardly towards the vessel, particulate heat insulating material disposed between the vessel and the framework, the outer face of said material extending at the natural angle of repose thereof respectively between each lamella and the next lower lamella the material being constrained against the vessel and out of contact with the outer casing.

11. A fluid storage tank comprising a storage vessel, an outer casing spaced from the vessel, a framework located between the vessel and the outer casing and spaced both from the vessel and the outer casing said framework comprising in vertical section a number of vertically spaced apart turns of a single helical strip an upper surface of said turns inclined downwardly towards the vessel, particulate heat insulating material disposed between the vessel and the framework, the outer face of said material extending at the natural angle of repose thereof between each turn and the upper surface of the next lower turn, the material being contrained against the vessel and out of contact with the outer casing.

12. A fluid storage tank according to claim 11 comprising circumferentially spaced vertically extending supports disposed inwardly of the strip the supports being V-shaped in horizontal section having two arms formed with inclined slots to receive the turns.

References Cited THERON E. CONDON, Primary Examiner.

I. R. GARRETT, Assistant Examiner.

Claims

1. A FLUID STORAGE TANK COMPRISING A STORAGE WHEEL, A FRAMEWORK LOCATED OUTWARDLY OF THE SPACED FROM THE VESSEL, SAID FRAMEWORK COMPRISING IN VERTICAL SECTION A NUMBER OF VERTICALLY SPACED ANNULAR RADIALLY INWARDLY AND DOWNWARDLY SLOPING MEMBERS, PARTICULATE HEAT INSULATING MATERIAL DISPOSED BETWEEN THE VESSEL AND THE FRAMEWORK, THE EXTERIOR FFACE OF SAID MATERIAL EXTENDING AT THE NATURAL ANGLE OF REPOSE THEREOF RESPECTIVELY BETWEEN EACH MEMBER, AN OUTER CASING SURROUNDING AND SPACED FROM THE FRAMEWORK, A HOPPER AT THE UPPER EXTREMITY OF THE OUTER CASING AT LEAST ONE WALL OF THE HOPPER HAVING AN INCLINATION GREATER THAN THE NATURAL ANGLE OF REPOSE OF THE MATERIAL THE SAID MATERIAL EXTENDING FROM THE UPPER PART OF THE FRAMEWORK INTO THE HOPPER AND MEANS FOR MOVING ANY OF SAID MATERIAL SPILLED INTO THE LOWER PART OF THE SPACE BETWEEN THE FRAMEWORK AND THE OUTER CASING TO THE HOPPER.