WO2020108879A1

WO2020108879A1 - Sliding connection for compressed air storage tank made of prestressed concrete

Info

Publication number: WO2020108879A1
Application number: PCT/EP2019/078843
Authority: WO
Inventors: Navid SAEEDI
Original assignee: IFP Energies Nouvelles
Priority date: 2018-11-27
Filing date: 2019-10-23
Publication date: 2020-06-04
Also published as: FR3088985B1; FR3088985A1

Abstract

The present invention relates to a pressure tank comprising at least two sections including a bottom (3). The junctions between the different sections may be of different types but comprise at least one sliding connection (2), preferably at least one sliding connection (2), the sliding axis being the longitudinal axis of a section of a substantially cylindrical portion (1) of the pressure tank. The sliding connections (2) allow the reduction or even elimination of the longitudinal stresses on the section of the substantially cylindrical portion (1), induced by the end-cap effect due to the internal pressure of the tank. The invention also relates to a means for storing and releasing energy comprising at least one compression means, at least one expansion means, at least one heat storage means, and at least one pressure tank as described above.

Description

SLIDING CONNECTION FOR PRESSURE CONCRETE COMPRESSED AIR STORAGE TANK

Technical area

The present invention mainly relates to the field of energy storage by compressed air but could be applied to other pressure tank systems.

The production of electricity from renewable energies, for example through solar panels, or onshore or offshore wind turbines, is booming. The main drawbacks of these means of production are the intermittence of production and the possible mismatch between the period of production and the period of consumption. It is therefore important to have a means of storing energy during production to restore it during a period of consumption.

There are many technologies that allow this balance.

Among them, the best known is the Pumped Water Transfer Station (STEP) which consists of the use of two water tanks at different altitudes. Water is pumped from the lower basin to the upper basin during the charging phase. The water is then sent to a turbine, in the direction of the lower basin, during the discharge.

The use of batteries of different types (lithium, nickel, sodium-sulfur, lead-acid ...) can also meet this need for energy storage. Another technology, rotor energy storage (FES) is to accelerate a rotor (flywheel) at a very high speed and keep the energy in the system in the form of kinetic energy. When energy is extracted from this FES system, the speed of rotation of the flywheel is reduced as a consequence of the energy conservation principle. Adding energy to the FES system therefore increases the speed of the steering wheel.

Energy storage technology using compressed gas (often compressed air) is promising. The energy produced and not consumed is used to compress air at pressures between 40 bar and 200 bar using compressors (which can be multi-stage). During compression, the air temperature increases. In order to limit the cost of the storage tanks and minimize the electricity consumption of the compressor, the air can be cooled between each compression stage. The compressed air is then stored under pressure, either in natural cavities (caves) or in artificial reservoirs. During the electricity production phase, the stored air is then sent to turbines in order to produce electricity. During expansion, the air cools. In order to avoid temperatures that are too low (-50 ^) leading to damage in the turbines, the air can be warmed up before expansion. Such installations have been in operation for a number of years, such as the Huntorf unit in Germany operating since 1978 or the Macintosh unit in the USA (Alabama) operating since 1991. These two installations have the particularity of using the stored compressed air to supply gas turbines. These gas turbines burn natural gas in the presence of pressurized air in order to generate very hot (550 ^ and 825Ό) and high pressure (40 bar and 11 bar) combustion gases before expanding them in turbines generating electricity. This type of process emits carbon dioxide. The Huntorf unit could emit around 830 kg of C0 ₂ per megawatt of electricity produced.

There is a variant in development. This is a so-called adiabatic process in which the heat from the compression of the air is recovered, stored and returned to the air before it is released. This is AACAES technology (from the English "Advanced Adiabatic Compressed Air Energy Storage").

In an AACAES system, compressed air is stored in a tank independently of heat storage. In such a system, the air is stored at a temperature close to ambient temperature (a priori less than 50 ^< ).

Prior art

To date, the compressed air tanks and, more broadly, the pressure tanks, are closed capacities made up of at least two ends, also called “bottoms”, and possibly connected by an intermediate part such as on the Fig 1, where P represents the internal pressure. In this figure, the reservoir is represented, in a nonlimiting manner by a cylindrical part (the direction r being the radial direction and the direction z the axial direction of a cylindrical reference associated with the reservoir - this reference is used in the other figures and will not be re-detailed on each figure) of internal diameter D ,. Thus, this type of reservoir can be, for example, a sphere formed by two half-spheres or else by a cylindrical capacity made up of two bottoms connected together by a cylindrical section. The connections between the different parts are rigid, built-in type.

In addition, these tanks are most often made of steel, to withstand high pressures. Given the large storage volumes, the cost of producing these large volume pressure tanks is very high. In a closed cylindrical tank, the bottom effects, resulting from the application of the internal pressure on the bottom of the tank, generate tensile forces in the longitudinal direction and therefore axial stress oll, as in Fig 1. Whatever the shape of the bottom (flat, domed, hemispherical, etc.), the bottom effects of this type of tank generate the following average longitudinal stress in the current part of the tank:

[Math 1]

P D?

° ⁿ 4 t {Di + t)

Where P: is the pressure applied in the tank

D,; the internal diameter of the tank

t: the thickness of the tank wall at the level of the cylindrical part

When the pressure tank is thin-walled, we obtain:

[Math 2]

A thin-walled pressure tank is understood to mean a pressure tank whose thickness of the tank is very small compared to its diameter (by small thickness compared to its Diameter is meant a t / Di ratio <5%).

Furthermore, the principle of prestressed concrete pipes is known, pipes mainly intended for the transfer of fluid (sanitation, water transfer, etc.) with low operating pressures (less than 20 bar and most often less than 5 bar ). Indeed, to take up the effects of significant pressure bottoms in prestressed concrete pipes, the use of longitudinal prestressed steel cables is essential, as the concrete is not intended to take up significant tensile stresses. However, the installation of these steel cables considerably increases the price of prestressed concrete pipes, so that the use of prestressed concrete pipes for high pressures proves to be economically unsustainable.

Patent FR 3 055 942 A1 relates to the current section of composite pipes of steel and prestressed concrete, but does not specify the type of connections between these mixed pipes.

The invention relates to a closed pressure tank comprising at least two sections linked by connections. The sections delimiting the walls of the pressure tank. The sections comprise at least one element of substantially cylindrical section and a bottom. In addition, the pressure tank comprises at least one connection of sliding type sections, the sliding axis of the sliding connection being coaxial with the axis of the element of substantially cylindrical section and the sliding connection comprising a means of sealing. In addition, the sliding connection is positioned at the junction of one of the elements of substantially cylindrical section with another section. In this way, the background effects linked to the internal pressure are considerably reduced, which makes it possible to reduce the mass and the cost of the tank. The length over which the two sections can slide is provided to maintain the guide and the seal between these two sections.

The invention also relates to a means of energy storage and restitution comprising a pressure tank of this type, a compression means, an expansion means and a heat storage means.

Summary of the invention

The invention relates to a pressure tank, said pressure tank being closed and comprising at least two sections linked by connections, said sections delimiting the walls of said pressure tank, said at least two sections comprising at least one element of substantially cylindrical section. and a background. In addition, said pressure tank comprises at least one connection of sliding type sections, the sliding axis of each sliding connection being coaxial with the axis of said element of substantially cylindrical section, each sliding connection comprising a sealing means, each sliding connection being positioned at the junction of one of said at least one element of substantially cylindrical section with another section.

Preferably, said pressure tank comprises at least two connections of sliding type sections and at least three sections.

Advantageously, at least one sliding connection is made by two coaxial cylinders and a shoulder.

According to one embodiment of the invention, at least one sliding connection is positioned at the junction between an element of substantially cylindrical section and a bottom, preferably, two sliding connections are positioned at the junction between an element of substantially cylindrical section and a fund.

According to a variant, the elements of substantially cylindrical section are of diameter less than the diameters of the bottoms, at the level of their sliding connection.

According to another variant, the elements of substantially cylindrical section are of diameter greater than the diameters of the bottoms, at the level of their sliding connection. Advantageously, said sealing means is positioned between the outside diameter of the smallest section at said sliding connection and the inside diameter of the other section of said sliding connection.

Alternatively, the sealing means has an inside diameter equal to the inside diameter of each of the sections connected by said sliding connection.

Advantageously, at least one of said at least two idious sections is made of prestressed concrete.

Preferably, the sections are made of waterproof formulation concrete.

According to one embodiment of the invention, said tank comprises a single element of substantially cylindrical section.

According to another embodiment of the invention, said tank comprises a plurality of elements of substantially cylindrical section.

Advantageously, sliding connections are positioned at each of the ends of each of said elements of substantially cylindrical section.

Preferably, said elements of substantially cylindrical section are assembled by prestressed longitudinal cables and a sealing system is positioned at the junction between said elements of substantially cylindrical section.

According to a variant, said sealing system comprises a sealing layer placed on the internal face of the tank and extending along all of said elements of substantially cylindrical section assembled by said preloaded longitudinal cables.

Advantageously, said sealing system comprises membranes at the interface between said elements of substantially cylindrical section assembled by said prestressed longitudinal cables, said membranes being preferably made of a polymer or cement-based material.

The invention also relates to a means of energy storage and return comprising at least one compression means, at least one expansion means, at least one heat storage means and at least one pressure tank, according to the invention. one of the previous features.

List of Figures

[Fig 1]

Figure 1, already described, shows a cylindrical reservoir according to the prior art and the longitudinal stress resulting from the resulting background effects.

[Fig 2]

FIG. 2 represents an embodiment of a tank provided with sliding connections, according to the invention.

[Fig 3] FIG. 3 represents a second embodiment of a tank provided with sliding connections, according to the invention.

[Fig 4]

FIG. 4 represents the longitudinal stress resulting from the bottom effects in a tank provided with sliding connections, according to the embodiment of FIG. 2, according to the invention.

[Fig 5]

FIG. 5 represents the longitudinal stress resulting from the background effects in a tank provided with sliding connections, according to the embodiment of FIG. 2, according to the invention.

[Fig 6]

FIG. 6 represents a third embodiment of a tank provided with sliding connections, according to the invention.

[Fig 7]

FIG. 7 represents an embodiment of a current part of a tank provided with sliding connections, according to the invention.

[Fig 8]

FIG. 8 represents an embodiment of a current part, produced in several blocks, of a tank provided with sliding connections, according to the invention.

[Fig 9]

FIG. 9 represents a second embodiment of a main part, produced in several blocks assembled by sliding connections, of a tank provided with sliding connections, according to the invention.

[Fig 10]

FIG. 10 represents the background effect and the longitudinal stress for the sliding connections between the blocks of the current part, according to FIG. 9.

Description of the embodiments

The invention relates to a closed pressure tank comprising at least two sections linked by connections. The sections delimiting the walls of the pressure tank. The sections comprise at least one element of substantially cylindrical section and a bottom and preferably, the sections can comprise at least two bottoms. In addition, the pressure tank comprises at least one connection of sections of the sliding type, for example, in operation of the tank, in particular when the pressure tank is under internal pressure. By using this sliding connection, when the pressure tank is under internal pressure, at least part (a section for example) may not not be subject to a substantive effect, or in any case subject to a significantly reduced substantive effect. By background effect is meant the effect induced by the internal pressure, which causes axial stresses on the reservoir. The sliding axis of this sliding connection is coaxial with the axis of the element of substantially cylindrical section, so as to reduce the bottom effects and the sliding connection comprises a sealing means to ensure the pressure resistance of the tank. . By sliding connection is meant that the sections connected by this sliding connection can move in a translation along the axis of the element of substantially cylindrical section. By moving by a longitudinal translation, the axial tensile forces, due to the bottom effect, on the element of substantially cylindrical section are reduced. The sliding connection is positioned at the junction of one of the elements of substantially cylindrical section with another section. In this way, the background effects linked to the internal pressure of at least part of the pressure tank (for example one or more sections or parts of sections) are considerably reduced thanks to the sliding connection, which makes it possible to reduce the mass and cost of the tank. This effect can be more particularly improved when this part of the tank is located between two sliding connections. In addition, the assembly of the different parts can be carried out directly on the installation site, which can reduce transport costs when the complete tank must be assembled in the factory.

Advantageously, the pressure tank can comprise at least two connections of sliding type sections, so as to further reduce the bottom effects of the element or elements located between these two sliding connections. In this case, the reservoir comprises at least three sections and preferably among these three sections, the reservoir comprises at least two bottoms.

Preferably, at least one sliding connection can be made by two coaxial cylinders and a shoulder, one of the cylinders sliding in the shoulder, and the other cylinder being fixed relative to the shoulder. Thus, the shoulder is used to assemble the connection in one of the sections. Furthermore, the shoulder can also be used to install the sealing means. Preferably, the shoulder can be arranged at one end of a section. Advantageously, the sealing means can be arranged between the sliding cylinder and the shoulder. Alternatively, the sealing means can be arranged longitudinally at the end of a cylinder.

According to one embodiment, at least one sliding connection can be positioned at the junction between a substantially cylindrical section element and a bottom and preferably, at least two sliding connections are positioned between a section element substantially cylindrical and each bottom. Indeed, the background effect induced by the funds, thus do not apply to the element of substantially cylindrical section or its effect is then considerably reduced.

According to a variant of the invention, the elements of substantially cylindrical section can be of diameter smaller than the diameters of the bottoms, at their sliding connection, that is to say the sliding connection connecting the element of cylindrical section and the bottom. This configuration is for example, schematically and without limitation, that of FIG 2, where the connections 2 are located between the element of substantially cylindrical section 1, which is here represented by a male element, and the bottoms 3, which are represented here by female elements.

In FIG. 4, the bottom effect due to the pressure P which is applied at the level of the sliding connection on the element of substantially cylindrical section is observed. The average longitudinal stress resulting from these background effects is calculated as follows:

[Math 3]

Where D _s is the sealing diameter, D, the internal diameter of the substantially cylindrical section member and t the thickness of the substantially cylindrical section member. In this system, D _s is greater than D ,, which implies that the longitudinal stresses are compression stresses. For a concrete tank without longitudinal prestressing, this system is advantageous because it allows to keep a little compression in the longitudinal direction, the concrete having a low tensile strength.

Alternatively, the elements of substantially cylindrical section may be of diameter greater than the diameters of the bottoms, at the level of their sliding connection connecting them. This configuration is for example, schematically and without limitation, that of FIG 3, where the connections 2 are located between the element of substantially cylindrical section 1, which is here represented by a female element, and the bottoms 3, which are represented here by male elements.

In Fig 5, we observe the background effect due to the pressure P which applies at the level of the sliding connection on the element of substantially cylindrical section. The longitudinal stress is calculated by the formula of Math 3. But in this system, D _s is less than D ,, which implies that the longitudinal stresses are tensile stresses.

As well in the case of fig 4 as in the case of fig 5, D _s is close to D ,, which implies that the resulting background effect is low, in particular compared to a pressure tank without sliding connections where D _s is zero. So, in both alternatives, the reduction of the longitudinal stresses linked to background effects is important and thus allows a reduction in the mass and cost of the tank.

According to one embodiment of the invention, the sealing means can be positioned between the outside diameter of the smallest section at the sliding connection and the inside diameter of the other section of the sliding connection, the sliding connection being itself located between the two sections, that is to say between the outer diameter of the smaller of the two sections and the inner diameter of the larger of the two sections. Thus, the sealing makes it possible to obtain a sealed tank.

Alternatively, the sealing means can have an inside diameter equal to the inside diameter of each of the sections connected by the sliding connection. This alternative is particularly interesting because it makes it possible to cancel or reduce to almost nothing the bottom effect of a section situated between two sliding connections of this type. This configuration is shown for example in Figure 6 between a bottom 3 and an element of substantially cylindrical section 1 but could also be used between two elements of substantially cylindrical section. The sealing means is positioned at the sliding connection 2, on the inside diameter, which is equal to the inside diameter of the cylindrical element. Thus, in theory, D _s is equal to D, and the resulting longitudinal stress (determined by equation [Math 3]) is then zero. In practice, it is never perfectly zero but reduced to a quasi-zero value.

According to one embodiment, at least one of the at least two sections can be made of prestressed concrete. Using pre-stressed concrete, rather than steel, reduces the cost of the tank. The prestressing of the concrete is in the circumferential direction, in all its length in order to resist the circumferential stresses induced by the internal pressure.

FIG. 7 shows an element of substantially cylindrical section 1 made of prestressed concrete where the part 10 is made of concrete and the reinforcements 20 represent the circumferential prestress reinforcements.

According to the invention, a sliding connection system makes it possible to avoid longitudinal traction in the current part of the tank. In this way, the prestressing cables can be avoided in the longitudinal direction. Knowing that in a conventional system of the prior art, the quantity of the longitudinal prestressing cables is proportional to the total length of the tank, the solution proposed according to the invention seems advantageous in the case of a long tank (ie large volume of storage). According to an advantageous embodiment, the sections can be made of waterproof formulation concrete. By “waterproof formulation concrete” is meant any formulation known to a person skilled in the art which makes it possible to reduce the porosity of the concrete obtained, compared with the usual porosity of a conventional concrete. Thus, the concrete can be sealed or semi-sealed, that is to say that its leak rate is low. As a result, the pressure resistance of the reservoir is improved.

According to a variant of the invention, the reservoir may comprise a single element of substantially cylindrical section. Thus, one can limit the number of sliding connections between the elements of substantially cylindrical section, and therefore the associated risk of leaks.

Alternatively, the reservoir may comprise a plurality of elements of substantially cylindrical section, preferably at least two cylindrical elements connected to each other by at least one sliding connection. This embodiment is advantageous for large structures, in order to carry out the assembly directly on site rather than in the factory so as to facilitate the transport of the various elements.

Preferably, sliding connections can be positioned at each of the ends of each of the elements of substantially cylindrical section. Thus, each of the substantially cylindrical elements is connected by sliding connections, so as to reduce the bottom effect applied to each of the substantially cylindrical elements.

According to a preferred variant of the invention, the pressure tank may comprise at least two elements of substantially cylindrical section and at least two bottoms, at least one sliding connection being positioned at the junction between one of the at least two elements of substantially cylindrical section and another of the at least two elements of substantially cylindrical section, at least two other sliding connections being positioned at the junction between one of the cylindrical elements with a bottom (each of these sliding connections connecting a different bottom to an element of substantially cylindrical section ),

[Fig 9] illustrates, schematically and without limitation, several elements of substantially cylindrical section comprising concrete blocks 10, each of these blocks comprising reinforcements 20 (for example metal cables) of circumferential prestress. At the junction between the different blocks 10, a sliding connection 100 comprising a shoulder allowing one of the blocks 10 to enter the connection is placed at one end of the other block 10. The detail of this connection 100 is illustrated in FIG 10. The sealing means 50 is illustrated and positioned between the shoulder of the sliding connection 100, allowing the junction between a first element of substantially cylindrical section 10 'and a second element of substantially cylindrical section 10 ”.

Advantageously, the elements of substantially cylindrical section can be assembled by prestressed longitudinal cables and a sealing system can be positioned at the junction between the elements of substantially cylindrical section. This embodiment is advantageous because the prestressed longitudinal cables make it possible to connect the elements of substantially cylindrical section without multiplying the sliding connections, which are more complex during assembly. The sealing means reduces leakage between the elements of substantially cylindrical section.

FIG. 8 illustrates several elements of substantially cylindrical section 1 comprising concrete blocks 10, each of these blocks comprising reinforcements 20 (for example, metallic cables) of circumferential prestressing. The longitudinal assembly of the blocks is ensured by prestressed longitudinal cables 30.

Advantageously, the sealing system may comprise a sealing layer placed on the internal face of the reservoir (for example, an internal “liner” made of polymer material or a cylinder of small metallic thickness) and extending along all elements of substantially cylindrical section assembled by the prestressed longitudinal cables. The use of this sealing layer makes it possible to reduce leaks, both at the junctions between the elements of substantially cylindrical section but also over the axial length of these elements. This is particularly valid for elements of substantially cylindrical section of concrete, the concrete being known to be a porous material, and therefore generating leaks. This sealing layer can also be resistant to physical and / or chemical damage or include a protective layer against this damage. The use of an inner rigid sealing layer throughout the tank makes it possible to overcome the sealing of the blocks of the tank.

Alternatively, the sealing layer could also be positioned outside the elements of substantially cylindrical section.

Preferably, the sealing system may comprise membranes at the interface between the elements of substantially cylindrical section assembled by said prestressed longitudinal cables, the membranes preferably being made of a material based on polymer, cement or cementitious product. Leaks can therefore be reduced at the junctions. The invention also relates to a means of energy storage and return comprising at least one compression means, at least one expansion means, at least one heat storage means and at least one pressure tank, according to the invention. one of the previous features. Indeed, the use of a pressure tank as described above makes it possible to considerably reduce the cost of the pressure tank, which is particularly useful by means of energy storage and restitution, the pressure tank being a factor. significant cost of the energy storage and return means. It is particularly suitable for the operation of AACAES type systems.

Claims

1. Pressure tank, said pressure tank being closed and comprising at least two sections (1, 3) linked by connections, said sections (1, 3) delimiting the walls of said pressure tank, said at least two sections (1, 3 ) comprising at least one element of substantially cylindrical section (1) and a bottom (3), characterized in that said pressure tank comprises at least one connection of sliding type sections (2), the sliding axis of each connection sliding (2) being coaxial with the axis of said substantially cylindrical section element (1), each sliding connection (2) comprising a sealing means, each sliding connection (2) being positioned at the junction of one of said at least an element of substantially cylindrical section (1) with another section (1, 3).

2. Pressure tank according to claim 1, comprising at least two connections of sliding type sections (2) and at least three sections (1, 3).

3. Pressure tank according to one of the preceding claims, in which at least one sliding connection (2) is produced by two coaxial cylinders and a shoulder.

4. Pressure tank according to one of the preceding claims, for which at least one sliding connection (2) is positioned at the junction between an element of substantially cylindrical section (1) and a bottom (3), preferably two connections sliding (2) are positioned at the junction between an element of substantially cylindrical section (1) and a bottom (3).

5. Pressure tank according to one of the preceding claims, for which the elements of substantially cylindrical section (1) are of diameter less than the diameters of the bottoms, at their sliding connection (2).

6. Pressure tank according to one of claims 1 to 4, for which the elements of substantially cylindrical section (1) are of diameter greater than the diameters of the bottoms, at their sliding connection (2).

7. Pressure tank according to one of the preceding claims, for which said sealing means is positioned between the outside diameter of the smallest section at said sliding connection and the inside diameter of the other section of said sliding connection ( 2).

8. Pressure tank according to one of claims 1 to 5, for which the sealing means has an internal diameter equal to the internal diameter of each of the sections connected by said sliding connection (2).

9. Pressure tank according to one of the preceding claims, for which at least one of said at least two sections is made of prestressed concrete.

10. Pressure tank according to one of the preceding claims, for which the sections are made of waterproof formulation concrete.

1 1. Pressure tank according to one of the preceding claims, for which said tank comprises a single element of substantially cylindrical section (1).

12. Pressure tank according to one of claims 1 to 10, for which said tank comprises a plurality of elements of substantially cylindrical section (1).

13. Pressure tank according to claim 12, for which sliding connections (100) are positioned at each of the ends of each of said elements of substantially cylindrical section (1).

14. Pressure tank according to one of claims 12 or 13, for which said elements of substantially cylindrical section (1) are assembled by prestressed longitudinal cables (30) and a sealing system is positioned at the junction between said elements of substantially cylindrical section.

15. Pressure tank according to claim 14, for which said sealing system comprises a sealing layer placed on the internal face of the tank and extending along all of said elements of substantially cylindrical section (1) assembled by said prestressed longitudinal cables (30).

16. Pressure tank according to one of claims 14 or 15, for which said sealing system comprises membranes at the interface between said elements of substantially cylindrical section (1) assembled by said prestressed longitudinal cables (30), said membranes preferably being made of a polymer or cement-based material.

17. Energy storage and restitution means comprising at least one compression means, at least one expansion means, at least one heat storage means and at least one pressure tank, according to one of the preceding claims .