US3683574A

US3683574A - Cylindrical tank for containing high-pressure fluids

Info

Publication number: US3683574A
Application number: US38212A
Authority: US
Inventors: Franz Vaessen
Original assignee: HOCKTIEF AG fur HOCH und TIEFB
Current assignee: HOCKTIEF AG fur HOCH und TIEFB
Priority date: 1969-08-09
Filing date: 1970-05-18
Publication date: 1972-08-15
Anticipated expiration: 1989-08-15
Also published as: DE1940726A1; DE1940726B2; BE740935A; GB1224278A; NL137417C; FR2057080B1; NL6917999A; FR2057080A1

Abstract

A tank designed to contain high-pressure fluid, e.g. in a nuclear reactor, has a peripheral wall composed of concentrically nested concrete shells individually prestressed by surrounding wire coils; the several shells are separated by interposed antifriction layers preventing the transmission of substantial shear stresses therebetween. The top and bottom of the tank are formed by nested incurved concrete bowls, separated by antifriction layers, bearing upon stepped annular shoulders in an upper and a lower annular header secured by vertical tension cables to the peripheral wall.

Description

[is] 3,683,574 51 Aug. 15, 1972 United States Patent Vaessen [56] References Cited UNITED STATES PATENTS 3,397,503 8/1968 Adler.......................52/249X 3,443,631 5/1969 Bremer....................52/224X [54] CYLINDRICAL TANK FOR Tiefbau- Gebr. Helhnann, Essen,

Primary Examiner-John E. Murtagh Attorney-Karl F. Ross [57] ABSTRACT A tank designed to contain high-pressure fluid, eg in a nuclear reactor, has a peripheral wall composed of concentrically nested concrete shells individually prestressed by surrounding wire coils; the several ten vorm.

Germany [22] Filed: May 18, 1970 [2]] App]. No.: 38,212

[30] Foreign Application Priority Data 19 40 7262 shells are separated by interposed antifriction layers preventing the transmission of substantial shear Aug. 9, 1969 Germany.........

stresses therebetween. The top and bottom of the tank are formed by nested incurved concrete bowls; separated by antifriction layers, bearing upon stepped ...G2lc 13/04, G2lc 13/08 .52/249, 224; 176/87; 165/47; 220/3 [52] US. Cl. [51] Int. [58] Field of Search....

12 Claims, 8 Drawing Figures qkv mm hq annular shoulders in an upper and a lower annular header secured by vertical tension cables to the peripheral wall.

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SHEET Q (If 5 NNNNNN OR PATENTEDAUBIS I972 3583- 574 snmsors INVENTOR FRANZ VAESSEN ATTORNEY CYLINDRICAL TANK FOR CONTAINING HIGH- PRESSURE FLUIDS My present invention relates to a tank designed for the containment of high-pressure fluid. Although of general utility, such a tank is particularly suitable for use with nuclear reactors which are subject to considerable internal fluid pressures.

In principle, prestressed concrete is eminently suitable as a construction material for such vessels. As their size increases, however, the static stress conditions become progressively more complicated so that a proper layout of the prestressing elements can be realized only with increasing difficulty. This applies, for example, to a pressure-tank construction with a cylindrical peripheral wall of reinforced concrete girded by tensionable hoops; as the wall thickness increases, the expansion-resisting radial forces are supplemented by peripheral shear stresses which are only imperfectly absorbed by the concrete and its slack reinforcements. Other problems arise at the end walls, i.e., at the top and bottom of a cylindrical vessel with upright axis, where the axial pressures increase as the square of the diameter whereas the size of the area available for joining the end wall to the peripheral wall (i.e., the circumference of the cylinder) increases only as a linear function of diameter.

It is, therefore, the general object of my present invention to provide an improved tank construction for the containment of high-pressure fluids which avoids the aforestated problems.

More specifically, my invention aims at providing a cylindrical vessel of prestressed concrete in which the shear stresses normally generated by encircling prestressing means are substantially eliminated.

Another more particular object of this invention is to provide an improved junction between the peripheral wall and the two end walls of such a vessel.

In accordance with the present invention, l subdivide the cylindrically shaped peripheral wall into a multiplicity of concentrically nested concrete shells individually prestressed to resist radial outward deformation, as by means of enveloping elastic sheaths formed from steel wire wound about these shells in a multiplicity of turns, with interposition of antifriction means between the shells to prevent the transmission of major shear stresses from one shell to the other.

Advantageously, the two end walls are of inwardly curved configuration and are received within the axially opposite extremities of the peripheral wall so as to bear thereagainst in response to internal pressures tending to flatten these end walls. In extending the aforedescribed principles to the construction of the end walls, I prefer to subdivide each of them into a multiplicity of nested concrete bowls with interposed antifriction layers. The rims of these bowls, in a preferred embodiment, bear upon respective frustoconical zones on the inner peripheral surface of the cylinder wall, this surface having a sawtooth profile with flanks defining the generatrices of the frustoconical zones and lying substantially on the radii of curvature of the corresponding bowls.

According to another advantageous feature of my invention, the cylinder wall or some of its shells may be axially split into a stack of annular sections held together by tie rods passing through axially extending channels in some or all of the shells. In this case the outermost section or sections at each end of the cylinder may serve as a header framing the dished end wall and may also be provided with an internal annular shoulder forming a seat for the innermost bowl of that end wall; in contradistinction to the cylindrical wall between these headers, the header-forming sections should not include antifriction layers between their concentric rings so that both radial and nonradial stresses may be transmitted therebetween.

It may also be desirable, for easier assembly, to split some or all of the shells or their axially stacked sections into two or more segments held together by the surrounding prestressing means.

The invention will be described in greater detail hereinafter with reference to the accompanying drawing in which:

FIG. 1 is a longitudinal sectional view of a cylindrical high-pressure tank embodying my invention, with an intermediate portion of the cylinder wall broken away;

FIG. 2 is a cross-sectional view taken on the line II- II of FIG. 1;

FIGS. 3, 4, 5 and 6 are enlarged detail views of areas within outlines III, IV, V and VI, respectively, of FIG.

FIG. 7 is a view similar to FIG. 3, showing a modification; and

FIG. 8 is an enlarged detail view of an area outlined by the circle VIII in FIG. 2.

The tank shown in FIGS. 1 and 2 comprises a cylindrical peripheral wall 1 constituted by a multiplicity of concrete shells la, 1b, 1h with interposed antifriction layers generally designated 3. The shells 1a etc. are internally provided with conventional slack or unstressed reinforcements 7, as illustrated diagrammatically in FIG. 8, and are individually prestressed by elastic sheaths consisting (as best seen in FIGS. 3 and 7) of multiple turns of steel wire 2, a few millimeters in thickness, advantageously distributed over their entire outer surfaces. The antifriction layers 3 may consist of sheet metal, e.g., steel or aluminum, provided with lowfriction plastic coatings 4', 4" of Teflon or the like as illustrated in FIG. 3; FIG. 7 shows two

layers

3, 3" of helically coiled metal strips adjoining each other in staggered relationship.

As further illustrated in FIG. I, the shells 1a, 1b etc. are axially subdivided-except for the outermost shell lh-into rings forming axially stacked wall sections such as those designated 9, 9', 9". The two last-mentioned wall sections together constitute an annular header 8, framing the end wall 14, within the upper extremity of the outermost shell 1h; a similar header 8 for end wall 13 is constituted by the two lowermost sections of the cylinder wall 1. The several sections are cemented together by grouting 22 and are anchored to one another by vertical tie rods 6 traversing axially extending channels 5 (FIG. 8) in the shells Ia lg; these tie rods, illustrated only diagrammatically and over part of their length in FIG. 1, end in conventional terminal members (not shown) mating with clamping nuts or the like which bear upon the outer faces of the top and bottom wall sections.

The peripheral wall 1 is complemented by two

end walls

13, 14 to a closed vessel. The upper end wall 14 rests on an internal annular shoulder 23 integral with the innermost ring of wall section 9, i.e., the ring forming part of shell 1a; the lower end wall 13 bears upon a similar abutment 22'. Since the two end walls are symmetrical, a detailed description of the upper wall 14 will suffice.

In the region of the end plates, i.e., within headers 8 and 8', the elimination of tangential shear forces between adjoining shells is no longer necessary or even desirable. Therefore, as best illustrated for the section 9" in FIG. 4,

sections

9, 9" (and their counterparts at the bottom of the vessel) lack the

antifriction layers

3 or 3', 3" (FIGS. 3 and 7) of the remaining sections. On the contrary, the annular layers such as 1 of these wall sections (traversed by the tie rods 6 in channels are formed with serrated profiles along their inner peripheral surfaces confronting the wire sheath 12 of an adjoining layer, the intervening space being filled with grout 1 l to fonn a rigid bond between these layers and the intervening prestressing means 12 (which may be integral extensions of the wire coils 2 shown in FIGS. 3 and 7). Thus, the headers 8 and 8' may be regarded as annular structures of solid peripherally prestressed concrete surrounding the

corresponding end walls

14 and 13 in stress-transmitting relationship therewith. The serration 10 has a profile designed to transmit axially outwardly directed stresses, such as those resulting from internal gas pressure acting upon end wall 14, from an inner layer to an adjoining outer layer whereby these stresses are distributed over the entire header 8 for absorption by the tie rods 6.

The

end walls

13 and 14 are each composed of a multiplicity of bowl-shaped concrete layers 15 which are generally spherically curved with outwardly facing concavities. As best seen in FIG. 5, these concrete bowls are separated by antifriction layers 16', 16 e.g., in the form of spirally coiled or concentrically disposed metal strips with relatively offset edges, though of course a composite sheet such as that shown in FIG. 3 could also be used. As illustrated in FIG. 6, the bowls 15 may be provided with unstressed reinforcements, not shown, and also have stirrups 19 projecting from their rims to confront similar stirrups projecting inwardly from frustoconical zones 18 on the inner surfaces of the innermost rings of

wall sections

9 and 9";

stirrups

19 and 20 are joined together, rigidly (as by welding) or in articulated fashion, before the surrounding clearance is filled with grout 21. The zones 18 form part of a sawtooth profile 17 whose flanks constitute abutments, through the intermediary of grouting 21, for the rims of respective bowls 15. It will be noted that the generatrices of the frustoconical zones 18 substantially coincide with radii of curvature of the corresponding bowls 15, i.e., lie at right angles to lines tangent to these bowls at their rims.

A metallic inner core is shown surrounded by the

vessel

1, 13, 14 of prestressed concrete. For ease of assembly, and as illustrated in FIG. 2, the shells 1a 1h may be peripherally subdivided into part-cylindrical segments with relatively staggered joints, two semicylindrical segments per shell having been shown by way of example.

The constituent layers la 111 of cylinder 1 and 15 of concrete foundation cast in place.

Core 25 could also be made of materials other than metal, including concrete.

I claim:

1. A tank for the containment of a high-pressure fluid, comprising a cylindrically shaped peripheral wall and a pair of end walls complementing said peripheral wall to a closed vessel; said peripheral wall consisting essentially of a multiplicity of concentrically nested concrete shells, individual prestressing means for said shell resisting radially outward deformation, and antifriction means interposed between said shells for preventing the transmission of major shear stresses therebetween.

2. A tank as defined in claim 1 wherein said prestressing means comprises an elastic sheath enveloping each of said shells.

3. A tank as defined in claim 2 wherein said sheaths are formed from steel wire wound in a multiplicity of turns about each shell.

4. A tank as defined in claim 1 wherein said antifriction means comprises at least one layer of sheet material inserted between any two adjoining shells.

5. A tank as defined in claim 1 wherein at least some of said shells are peripherally subdivided into partcylindrical segments.

6. A tank as defined in claim 1 wherein at least some of said shells are axially subdivided into rings forming stacked annular sections of said peripheral wall.

7. A tank as defined in claim 6 wherein said rings are provided with axially extending channels, further comprising tensioned tie rods traversing said channels for holding said sections together.

8. A tank as defined in claim 1 wherein said peripheral wall terminates axially in at least one annular header of solid peripherally prestressed concrete surrounding the corresponding end wall in stress-transmitting relationship therewith.

9. A tank as defined in claim .8 wherein said peripheral wall is provided with anchor means engaging said header under axial stress.

10. A tank as defined in claim 9 wherein said corresponding end wall consists essentially of a multiplicity of nested bowl-shaped concrete layers with interposed antifriction means, said layers having circular rims bearing upon the inner peripheral surface of said annular header.

11. A tank as defined in claim 10 wherein said inner peripheral surface has a sawtooth profile defining a multiplicity of frustoconical zones centered on the cylinder axis, said layers being generally spherically curved along radii substantially coinciding with the generatrices of said zones.

12. A tank as defined in claim 1 wherein said end walls are inwardly curved bowls surrounded by respective axial extremities of said peripheral wall in stresstransmitting relationship therewith.

Claims

9. A tank as defined in claim 8 wherein said peripheral wall is provided with anchor means engaging said header under axial stress.

12. A tank as defined in claim 1 wherein said end walls are inwardly curved bowls surrounded by respective axial extremities of said peripheral wall in stress-transmitting relationship therewith.