EP0266335B1 - Container for storing liquids under pressure - Google Patents

Abstract

The invention relates to a pressurized fluid storage tank (1) adapted to be disposed underground at a slight depth. The invention comprises a ring (2) forming the side wall of the tank and two horizontal circular walls disposed in said ring and forming respectively the bottom wall (4) and the top wall (9) of the tank (1). Tie rods (8) are disposed between the top wall (9) and the bottom wall (4), these tie rods (8) being adapted to take the stresses resulting from the pressure of the stored fluid on said bottom wall (4) and top wall (9), leakproofing means (10) adapted to make the tank impervious to the fluid stored lining the interior of the tank (1). The tank (1) according to the invention permits storage under excellent conditions of inconspicuousness and safety. The invention is more particularly applicable to the storage of pressurized fuel fluids.

Description

The invention relates to a pressurized fluid storage tank which can be buried at a shallow depth.

The storage tank according to the invention applies more particularly to the storage of combustible gas in large quantities.

The entry into service of liquefied gas transporters has brought back to the fore the need for large volume storage tanks for pressurized combustible fluids. Such reservoirs can both serve as storage reserves near gas terminals and as buffers to attenuate irregularities in network demand.

The form in which the fluid is stored largely determines the technology of storage tanks.

From a technological point of view, a distinction is made between low pressure storage tanks and high pressure storage tanks.

Gasometers are part of the low pressure technique. They consist of a dome supported by concentric rings which can slide vertically with respect to each other; the whole, of variable volume, being supported by the internal pressure of the gas. Such reservoirs, often supported in addition by an external metallic structure, are unsightly and, by their dimensions, constitute easily identifiable targets for malicious people.

In cryogenic storage tanks, the gas is kept in liquid form at very low temperature, which makes it possible to store it under pressures close to atmospheric pressure.

These cryogenic tanks are provided with a double jacket, an external jacket protecting the tank against external agents and a second jacket capable of containing liquefied gas and resistant to very low temperatures (of the order of -40 ° C to -160 ° C) prevailing in the enclosure. Between these two envelopes is placed an insulator intended to limit the heat losses through the enclosure. The losses of cold through the envelope are generally compensated by a controlled evaporation of the fluid contained in the tank. The cost of producing these reservoirs, as well as their management cost, is high.

For high pressure storage tanks, the spherical shape is generally used, the sphere constituting the technically optimal shape.

The spherical envelope and its external frame are however, by their dimensions, highlighted in a landscape. These spherical reservoirs therefore constitute, like gasometers, significant visual disturbance and prime targets for malicious actions. Furthermore, these reservoirs are subjected to the direct action of atmospheric agents such as soliare radiation which can generate excessive thermal and mechanical stresses there.

Another way of resisting the high pressure generated by the stored fluid is to place the reservoir in a medium which in turn exerts a back pressure on the walls.

This solution applies, for example, by digging deep cavities in the clay. This material is gas tight and the weight of the earth and the pressure of the water table develop the back pressure ensuring the stability of the tank.

In other types of soil, back pressure can be exerted by the water table alone; in some cases, the wall of the underground tank is lined with a waterproof envelope.

The deep underground storage tanks have the advantage of discretion over the other types of tanks mentioned and blend harmoniously into the environment.

Their disadvantage is mainly due to the high cost of digging. Furthermore, the basement does not always lend itself to the installation of storage tanks of this type.

We therefore sought to achieve a type of storage tank as discreet, out of sight and out of reach of a malicious action as a tank buried at great depth, with however operating costs identical to those of a tank surface spherical.

The object of the invention is to be able to store combustible fluids under pressure under excellent conditions of reliability.

Another object of the invention is to carry out this storage under good economic conditions.

Yet another object of the invention is a storage tank of discreet shape, which can be covered with a slope or buried at a shallow depth.

• une virole formant la paroi latérale du réservoir,
• une paroi inférieure de forme circulaire disposée dans la partie inférieure de la virole,
• une paroi supérieure de forme circulaire disposée dans la partie supérieure de la virole, ces parois inférieure et supérieure n'étant pas liées rigidement à la virole,

The subject of the present invention is a high pressure fluid storage tank, which comprises:

• a ferrule forming the side wall of the tank,
• a circular bottom wall arranged in the lower part of the shell,
• an upper wall of circular shape disposed in the upper part of the shell, these lower and upper walls not being rigidly connected to the shell,

tie rods arranged vertically between the lower wall and the upper wall of the tank, the ends of these tie rods being secured respectively to the lower and upper walls, said tie rods being able to take up the forces produced on the lower and upper walls by the pressure of the stored fluid,

sealing means capable of rendering said reservoir sealed with stored fluid.

According to an advantageous embodiment, the ferrule comprises at the lower part of its internal face a cantilevered rib on which the lower wall is supported by its peripheral part, a watertight seal being interposed between this peripheral part and said rib. In this case, the bottom wall is advantageously connected to said rib by means of articulated anchors capable of allowing small relative movements between the shell and the bottom wall.

Similarly, the ferrule advantageously comprises, at the upper part of its internal face, a cantilevered rib against which the upper wall is supported by the peripheral part of its upper face, a watertight seal being interposed between this part peripheral and said rib.

According to a particular embodiment, the lower end of the ferrule is bevelled on the side of its internal face and has, on the side of its external face, a projection projecting from the external surface of the ferrule to allow the setting in place by havage.

The shell and the lower and upper walls can be made of concrete or steel.

According to one embodiment, the shell and the lower and upper walls are made of reinforced concrete and / or prestressed concrete. One can in particular realize the shell in prestressed concrete, while the lower and upper walls are made of reinforced concrete.

When the shell and the lower and upper walls are made of concrete, it is generally advantageous or even necessary for the internal surface of the tank to be coated with a lining made of a material impermeable to the stored fluid and compatible with this fluid.

This lining may in particular be made of metal and in this case it includes an expansion bellows in the zone where the ferrule meets the upper wall.

This waterproof lining can also be made of a material chosen from plastomers and elastomers.

It will be understood that the material used for producing the lining is chosen according to the type of fluid to be stored in the tank.

When the shell and the lower and upper walls are made of steel, the sealing of the reservoir can be ensured by a watertight lining in the zone where the shell and the lower wall meet and in the zone where the shell and the top wall.

The tie rods which are arranged vertically between the lower wall and the upper wall, may in particular consist of steel beams (such as H-beams) whose ends are provided with anchoring flanges. Tie rods of this type can be used both when the tank walls are made of steel and when they are made of concrete. In the latter case, the anchor plates of the tie rods are embedded in the concrete which forms the lower and upper walls.

However, when the tank walls are made of concrete, the tie rods can also consist of prestressed concrete columns.

The advantages of the tank according to the invention lie in that the gas can be stored under conditions of discretion and security similar to those of a storage tank at great depth, for a significantly lower production cost.

The reservoir according to the invention can be produced independently of the quality, the homogeneity and the mechanical characteristics of the soil. In addition to the advantages mentioned above, it will be noted that the storage tank according to the invention can be produced on site, using simple and proven construction techniques and under economical conditions.

Another advantage of the invention is that, as an underground reservoir, it benefits from an excellent isothermality, independent to a large extent of external climatic factors.

Another advantage is that the tank can be built entirely at ground level and lowered into place by havage; according to another embodiment, the reservoir is mounted in situ after the shroud of the shell forming the side wall. The volume of excavations is therefore reduced to a strict minimum and the footprint is thus limited.

The tank can also be produced according to conventional methods such as open excavation between embankments or under the shelter of a sheet pile curtain.

The reservoir according to the invention also allows a significant saving of space. Once the installation is complete, the surface of the land under which it lies can be used for any purpose. Even the erection of a building can be considered, the pressure generated on the ground by such a building, the pressure generated on the ground by such a building being incapable of affecting the reservoir.

The reservoir according to the invention is finally insensitive to subsequent drawdown work of the water table, which is not the case for deeply buried reservoirs.

The reservoir according to the invention, despite its large capacity, therefore discreetly integrates into the landscape and protects the stored fluid from malicious acts and accidents of external origin, impacts, explosions.

• la Fig. 1 est une vue en coupe suivant un plan vertical passant par l'axe d'un réservoir selon l'invention;
• la Fig. 2 est une vue en coupe suivant un plan horizontal II-II d'un réservoir selon l'invention;
• la Fig. 3 est une vue latérale en coupe avec arrachement partiel d'un tirant métallique;
• la Fig. 4 est une vue en coupe suivant un plan horizontal IV-IV d'un tirant métallique;
• la Fig. 5 est une vue latérale en coupe d'un détail de réalisation du doublage intérieur d'un réservoir en béton armé selon l'invention, et
• les Fig. 6 à 10 sont des vues en coupe schématiques de différents stades de construction par havage d'un réservoir.
• La Fig. 1 est une vue en coupe suivant un plan vertical passant par l'axe d'un réservoir enterré en béton armé selon l'invention.
• La paroi latérale du réservoir 1 est constituée par une virole 2 en béton armé précontraint.

Other features and advantages of the invention will emerge from the description of a particular embodiment, reference being made to the appended figures, in which:

• Fig. 1 is a sectional view along a vertical plane passing through the axis of a tank according to the invention;
• Fig. 2 is a sectional view along a horizontal plane II-II of a tank according to the invention;
• Fig. 3 is a side sectional view with partial cutaway of a metal tie;
• Fig. 4 is a sectional view along a horizontal plane IV-IV of a metal tie;
• Fig. 5 is a sectional side view of an embodiment detail of the interior lining of a reinforced concrete tank according to the invention, and
• Figs. 6 to 10 are schematic sectional views of different stages of construction by cutting a tank.
• Fig. 1 is a sectional view along a vertical plane passing through the axis of a buried reinforced concrete tank according to the invention.
• The side wall of the tank 1 is constituted by a ferrule 2 of prestressed reinforced concrete.

The seat of the tank 1 is provided by a layer of ballast concrete 3 which distributes the pressure on the ground and ballast the structure.

The bottom wall 4 of reinforced concrete is poured onto this ballast concrete 3. At its peripheral, this bottom wall 4 rests on a cantilevered rib 5 going around the ferrule 2. An articulated anchor 6 secures the ferrule 2 and the wall lower 4.

A double seal 7 provides an effective barrier against water infiltration.

Tie rods 8, the number of which depends on the dimensions of the tank, are described in more detail in FIG. 3. These tie rods 9 join the lower wall 4 to the upper wall 9. The lower end of these tie rods 8 is embedded in the lower wall 4; the upper end of these tie rods 8 is embedded in the upper wall 9.

A double 10 sealed with the stored fluid lines the internal face of the reservoir 1, as can be seen in more detail in FIG. 5.

The periphery of the upper wall 9 is inserted under a cantilevered rib 11 around the ferrule 2. The double seal 7 prevents any infiltration of water between the rib 11 and the upper wall 9.

A sealing yoke 12 covers the upper part of the reservoir 1, that is to say the external face of the upper wall 9, the rib 11 and the upper fringe of the ferrule 2. The reservoir 1 is covered by an embankment 13.

An access shaft 14 is attached to the side wall of the shell 2 and provides access to the interior volume of the reservoir 1. The reservoir 1 is connected to the distribution network by connection means of a well known technique, not represented.

Fig. 2 is a sectional view of the reservoir in a horizontal plane at the level of line II-II in FIG. 1.

Each of the small crosses represents a tie rod 8, the arrangement of these tie rods 8 being given purely by way of example.

A series of tie rods 8 are arranged vertically above the ribs 5 and 11, the other tie rods being distributed regularly over all of the walls 4 and 9 so as to take up the stresses in a homogeneous manner.

Fig. 3 is a side view of a tie rod 8 of the tank 1 according to the invention. The drawing 8 shown is constituted by a steel beam in H, 15; at the end of this beam 15, arranged perpendicularly thereto, is fixed an anchoring sole 16. Two trapezoidal inserts 17, arranged at right angles to the sole 16 and to the median section of the beam 15, reinforce the connection between the beam 15 and its sole 16.

The end of the beam 15 with its sole 16 is embedded in the concrete of the lower wall 4. A second sole 18 is fixed on the beam 15 at the level of the upper face of the wall 4. Two inserts 19 hold this sole 18 square to the tie rods 8. The plates 20 forming the waterproof lining 10 of the tank 1 are fixed, in this case by welding, to this second sole 18 so as to produce a continuous envelope. The upper end of the tie rod 8 is anchored in the upper wall 9 in an identical manner.

Fig. 4 is a sectional view along the line IV-IV of FIG. 3, of a metal tie rod 8 of the reservoir 1, on which the shape of the anchoring flange 16 and the H-profile of the beam 15 can be seen.

Fig. 5 is a sectional view of a detail of the interior lining of a tank 1 of reinforced concrete according to the invention. The edge of the lining plates 20 of the internal face of the ferrule 2 and of the lining plates 20 of the underside of the upper wall 9 is fixed to plates 21 fixed by daggers 22 to these walls. These plates 21 constitute holding lines for the lining 10. At the angle formed between the ferrule 2 and the upper proi 9, an expansion bellows 23 connects these two holding lines, ensuring both the continuity of the lining 10 and a possibility of relative movement of the lining 10 relative to each of the walls (2 and 9).

A shoe 24 is disposed between the lining 10 and the surface of the shell 2. This shoe 24 lowers the coefficient of friction of the lining 10 relative to the surface of the shell 2 and prevents wear due to the relative movements of these two parts.

Figs. 6 to 10 are schematic views, in section, of a method of producing the reservoir 1 according to the invention.

Fig. 6 shows the first stage of construction of the shell 2 constituting the side wall. The construction area is cleared and leveled by a pre-draft with drawdown 25.

The lower part of the shell 2 is built on site by formwork and is subjected to prestressing.

The lower end of the ferrule 2 is bevelled on the side of its internal face so as to form a cutter 26 facilitating the establishment by cutting the structure.

The lower end of the shell 2 also has, on the side of its external face, a protruding projection 27 relative to the external surface of the rest of the ferrule 2. With respect to this protruding projection 27, the rest of the external surface of the ferrule 2 thus has a reduction in diameter intended to provide between the external face of the ferrule 2 and the ground an annular gap 28. During the cutting, a fluid such as bentonite is pumped in this gap 28 so as to reduce the friction between the external face and the ground and thus limit the forces necessary for the establishment of the structure.

Fig. 7 is a schematic sectional view of the lower part of the shell 2 after the first stage of fitting by cutting.

The surface of the site delimited by the shell 2 having been gradually excavated, the shell 2 is gradually sinks into the ground, the excavation being supported by the shell 2 itself.

Fig. 8 is a schematic sectional view of the shell 2 after erection of its upper part. We then continue the installation by cutting the complete shell 2.

Fig. 9 is a schematic sectional view of the shell 2 having reached the final level of installation. The seat of the future tank 1 is ensured by a ballast concrete 3. A first cantilevered rib 5 is poured to support the lower wall 4 at its periphery.

Fig. 10 is a diagrammatic sectional view of the reservoir 1 after the lower 4 and upper 9 walls and the tie rods 8 have been fitted.

The operations are carried out as follows. We proceed to the reinforcement of the lower wall 4 and to the installation of the metallic tie rods 8. The concrete of the lower wall 4 is poured, joining the said lower wall 4 to the lower end of the tie rods 8. The laying of the lining is then carried out. watertight 10 of the lower wall 4 and of the shell 2. The upper wall 9 is shuttered, the lining 10 of the upper wall 9 installed. Finally, reinforcement and concreting of the upper wall 9 are carried out, after which the sealing screed 12 is laid and covered with an embankment 13.

The embodiment described above relates more particularly to a tank 1 made of concrete.

The tie rods 8 are in this case made up either of metal profiles or of prestressed concrete columns.

The tank according to the invention can also, as was said above, be made of steel.

In this case, the tie rods 8 are also made of steel. When the tank is made of steel, the installation of a waterproof lining 10 is generally not necessary. However, there is provided a curved sheet forming the connection between the side wall and, respectively, the bottom wall and the top wall.

For example, a storage tank with a diameter of around 35 m and an interior height of around ten meters can be produced where it can be stored at room temperature. soil, or about 10 ° C, 10,000 m ³ of propane gas at a pressure of 8 bars.

Claims (11)

1. Storage tank (1) for fluid under high pressure, characterized in that it comprises:

a ring (2) forming the side wall of the tank (1),

a bottom wall (4) of circular shape disposed in the bottom part of the ring (2),

a top wall (9) of circular shape disposed in the top part of the ring (2), these bottom wall (4) and top wall (9) being not rigidly bound to the ring (2),

tie rods (8) disposed vertically between the bottom wall (4) and the top wall (9) of the tank (1), the ends of said tie rods (8) being made fast to the bottom wall (4) and top wall (9) respectively, and said tie rods (8) being adapted to take the loads produced on the bottom wall (4) and top wall (9) through the pressure of the stored fluid,

and leakproofing means (10) adapted to make said tank (1) impervious to the stored fluid.

2. Tank (1) according to Claim 1, characterized in that the ring (2) is provided at the bottom part of its inside face with a cantilever rib (5) on which the bottom wall (4) is supported peripherally, a watertight seal (7) being interposed between its peripheral part and said rib (5).

3. Tank (1) according to Claim 2, characterized in that the bottom wall (4) is connected to the rib (5) by means of articulated anchorages (6) adapted to permit slight relative movements between the ring (2) and the bottom wall (4).

4. Tank (1) according to any one of the preceding claims, characterized in that the ring (2) is provided at the top part of its inside face with a centilever rib (11) against which the top wall (9) bears by the peripheral part of its top face, a watertight seal (17) being interposed between said peripheral part and said rib (11).

5. Tank (1) according to any one of the preceding claims, characterized in that the bottom end of the ring (2) is bevelled on its inside face so as to form a cutting edge (26), and is provided on its outside face with a portion (27) projecting in relation to the outside surface of the ring (2).

6. Tank (1) according to any one of the preceding claims, characterized in that the ring (2) and the bottom wall (4) and top wall (9) are composed of a material selected from reinforced concrete and prestressed concrete, the leakproofing means comprising a lining (10) of the inside surface of the tank (1) with a material, impervious to the fluid stored and compatible with said fluid.

7. Tank (1) according to Claim 6, characterized in that the leakproof lining (10) is made of metal and incorporates an expansion gusset (23) in the zone where the ring (2) and the top wall (9) meet.

8. Tank (1) according to Claim 6, characterized in that the leakproof lining (10) is made of a material selected from the plastomers and the elastomers.

9. Tank (1) according to any one of Claims 1 to 5, characterized in that the ring (2) and the bottom wall (4) and top wall (9) are made of steel, the leakproofing means comprising a lining (10) in the zone where the ring (2) and the bottom wall (4) meet and in the zone where the ring (2) and the top wall (9) meet.

10. Tank (1) according to any one of the preceding claims, characterized in that the tie rods (8) are steel beams (15) whose ends are provided with anchorage base plates (16).

11. Tank (1) according to any one of Claims 6 to 8, characterized in that the tie rods (8) are pillars of prestressed concrete.

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