OA21398A - Device for pumping water from great depths. - Google Patents

Abstract

The invention relates to a device for pumping water to great depths, comprising a plurality of longitudinal elements (8) assembled together to form a pipe inside which the water pumped to great depths circulates, in which each longitudinal element (8) comprises a wall (10), for example of thickness less than or equal to 5cm, forming a section of said pipe, said wall (10) being prestressed in traction, for example longitudinally and/or circumferentially, when water is not pumped into the pipe.

Description

Device for pumping water from great depths

Technical area

[0001]The present invention relates to deep water pumping devices. 5 In particular, the present invention relates to pipes, or risers, allowing. the transport of water from great depths to the surface.

. Prior technique

[0002] It is currently known to use pipes (or "risers" in English) to convey water, for example from seas or lakes, coming from great depths and at low temperature, to a platform or a boat. This low temperature water can then be used as a cold source in systems implementing a thermodynamic cycle to produce, for example, energy. In this case we speak of “ocean thermal energy” (ETM). Alternatively, this low temperature water can be used as a coolant for installations (air conditioning or natural gas liquefaction for example) present on the platform or the boat.

[0003]The pipe must be able to allow the rise of a large volume of water, typically several tens, or even hundreds, of thousands of cubic meters per hour, from great depths, for example several hundred meters.

This rise is carried out using pumping means located on the surface, for example pumps lowering the water level in the pipe relative to sea level, or located deep in the pipe.

[0004]It is therefore necessary to design a pipe having a large diameter, for example several meters, and capable of resisting: the forces generated by the connection with the surface support, dynamic pressure variations (such as the swell effect for example), the actions of currents, pressures and/or depressions.

[0005]There are thus metal pipes and/or composite materials, which can reach lengths of up to 150 meters.

[0006]Nevertheless, it is currently difficult to envisage such pipes with much greater lengths, for reasons of mechanical strength.

[0007] Furthermore, the installation of such pipes also remains problematic due to the length of said pipes which makes them difficult to handle.

[0008] Application WO 2019/097151 describes a pipe for pumping water at great depth, which has a greater length than previous pipes, and which can be installed more easily.

[0009]Nevertheless, such pipes can become unstable, particularly the wall, due to stresses due to the pressure difference between the inside ίο and the outside of the pipe, which can lead to deformation or crushing of the wall.

Presentation of the invention

[0010]The present invention aims to resolve the various technical problems stated previously. In particular, the present invention aims to provide a device for pumping water at great depth, with a pipe having a significant length and high mechanical stability, and which can be installed more easily.

[0011]Thus, according to one aspect, a device is proposed for pumping water at great depth, comprising a plurality of longitudinal elements assembled together to form a pipe inside which the pumped water circulates at great depth. Each longitudinal element comprises a wall, forming a section of said pipe, said wall being prestressed in tension, for example longitudinally and/or circumferentially, when the water is not pumped into the pipe.

[0012]The wall may have a thickness less than or equal to 5 cm, preferably less than 3 cm, or even 1 cm. Preferably, the wall may have a thickness of between 3 and 4mm.

[0013]Thus, the pipe according to the present invention comprises a wall which is prestressed. The purpose of prestressing is to limit the overall stresses that the wall will undergo when the pipe is used to pump water. In fact, to bring the cold water up inside the pipe, a depression is created inside it which causes stress in the wall. In order to limit such stresses, the wall is designed to be pre-stressed before pumping the water into the pipe. Thus, during pumping, the stresses created by the internal depression of the pipe, which are centripetal stresses, will be balanced, in the material of the wall, by the prestress which is a centrifugal prestress. In the end, the stresses exerted in the material of the wall oppose each other to lead to a lower final stress, limiting the risks of deformation, or even crushing, of the ίο wall.

[0014]Preferably, said prestress, for example radial or centrifugal, is chosen substantially greater than or equal, in amplitude, to the depression created inside to pump the water with the device, so as to balance the pressures exerted on the wall when water is pumped with the device.

[0015]By choosing a prestress of an amplitude similar to the prestress which is created inside the pipe, it is possible to obtain a low, or even zero, total stress exerted in the wall during its use.

[0016]Preferably, each longitudinal element comprises an individual frame, for example in the form of a crinoline, said wall being mounted on, and in particular inside, the frame.

[0017]The purpose of the reinforcement is to provide stable mechanical support, to create prestressing of the wall.

[0018] Preferably, the reinforcements are configured to connect together in a watertight manner, said longitudinal elements, for example comprising end portions with sealing means configured to cooperate with the end portions of the adjacent reinforcements.

[0019] The reinforcements can also be used to allow the assembly, in particular watertight, of the longitudinal elements between them, and to allow the mounting of the longitudinal elements on an external supporting structure.

Preferably, the wall of each longitudinal element is prestressed relative to the reinforcement. The reinforcement constituting a stable mechanical support for the longitudinal element, it can be used as support to create centrifugal, or radial, prestressing in the wall.

[0021]Preferably, the device comprises circumferential prestressing means of the wall, for example turnbuckles, and/or longitudinal prestressing means of the wall, for example tie rods, said circumferential and/or longitudinal prestressing means being mounted between the frame and the wall.

[0022]The circumferential or longitudinal prestressing means are mounted between the frame and the wall, and make it possible to exert a stress on the wall by bearing on the frame. Thus, in the case of reinforcement external to the wall, the circumferential or longitudinal prestressing means will be mounted between the reinforcement and the wall, and will be configured to be able to reduce their length, so as to create a centrifugal or radial prestress , or else a longitudinal, or axial, prestressing in the wall.

Preferably, the prestressing means, preferably circumferential, comprise an elastic means, for example spring washers mounted in the turnbuckles, to allow deformation of the prestressed wall, when water is pumped with the device.

[0024] The elastic means allows the prestressing means to deform under the effect of an external stress: this in particular allows the wall to deform under the effect of stresses linked to the internal depression of the pipe during pumping some water. Thus, the deformation of the wall during the installation of the initial prestress is not fixed, but can on the contrary change when the wall undergoes the stresses due to the difference in hydraulic pressure which balance the prestress. Thus, the wall can regain its initial shape, or geometry or dimension, before prestressing, when water is pumped with the device, thanks to the elastic means of the prestressing means. The elastic means allow, thanks to their deformation, the prestressed wall to deform under the effect of the stresses linked to the suction of water during the pump. The prestressing and the depression stresses compensate each other, the wall can then return to its initial shape, and undergo little mechanical stress.

[0025]Preferably, the frame comprises at least two, preferably three, 5 longitudinal means, for example bars, connecting the end portions of the frame together, and at least two, preferably four or more, peripheral means, for example tori, connecting the longitudinal means; between them.

[0026]The reinforcement is thus formed of bars and tori forming a cage ίο surrounding, or surrounded, by the wall. The reinforcement makes it possible to provide a multitude of support points for the prestressing means, distributed around the periphery of the wall.

[0027]Preferably, the device also comprises a supporting structure, and the longitudinal elements are individually mounted integrally on the supporting structure, preferably by the upper or lower end of their frame.

[0028] The device for pumping water at great depth, comprises on the one hand a supporting structure, for example comprising at least, preferably three or more, cables, and on the other hand a plurality of longitudinal elements forming the pipe inside which circulates the water pumped at great depth. The longitudinal elements are individually mounted integrally on the supporting structure, preferably by their upper or lower end, and are connected together by sealing means.

[0029]Thus, the pipe is made from longitudinal elements individually secured to a supporting structure. The pipe is therefore no longer a one-piece pipe formed in a single piece, but is formed by the assembly, via sealing means, of a plurality of longitudinal elements. In order to limit the mechanical stresses applying to the sealing means, but also to the longitudinal elements themselves, each longitudinal element is mounted integrally on the supporting structure, so that the sealing means do not have no mechanical function, which gives them a longer lifespan and greater efficiency. Furthermore, such a structure is easier to install in particular, since it is possible to mount successively, for example in situ on the platform or on the boat, the different longitudinal elements on the supporting structure as it progresses. this is submerged.

Preferably, the supporting structure comprises at least two, preferably three or more, cables, distributed around the periphery of the longitudinal elements.

ίο [0031] The supporting structure is formed here of several cables, for example made of steel, distributed around the periphery of the longitudinal elements. Such a supporting structure has the advantage of being flexible, and therefore of being able, for example, to be wound on a reel in order to facilitate its storage and transport, while having sufficient mechanical properties to support the weight of the various longitudinal elements. Thus, when installing the pipe, the cables of the supporting structure can be unrolled and the longitudinal elements of the pipe can be mounted there gradually.

[0032]Preferably, each longitudinal element comprises a fixing assembly allowing the individual reinforcement to be mounted on the supporting structure.

Preferably, the pipe section, or wall, is formed from aluminum alloy, steel or composite materials. Such a pre-stressed section of pipe makes it possible to guarantee the shape of the pipe, despite the pressure due to the difference in water height created inside the pipe to pump the cold water. It is then possible to control the flow of water circulating in the pipe with the vacuum applied at the top of the pipe. In addition, we also obtain better mechanical strength of the pipe as a whole which can thus better withstand the different stresses exerted on it. Finally, with a rigid structure, the flow of water circulating in the pipe remains constant along the entire length of the pipe. .

Preferably, the pipe section may comprise mechanical reinforcement means, for example one or more hoops mounted on an external peripheral surface of the pipe section.

[0035]The hoops make it possible to reduce the thickness of the pipe section, and therefore the weight of the pipe section, while still having the same mechanical properties thanks to the reinforcement of the hoops.

Preferably, the pipe section may comprise thermal insulation means, for example a nanoporous material placed on the interior or exterior peripheral surface of the section.

[0037] Preferably, the fixing assembly is mounted on the individual frame by first pivot connections, preferably two diametrically opposed on the periphery of the individual frame. The pivot connections between the individual frame and the fixing assembly provide a certain flexibility to driving. Indeed, the supporting structure, formed of cables, can deform to a certain extent depending on the stresses it undergoes, while the longitudinal elements of the pipe are rigid. The pivot connections make it possible to provide a degree of freedom, albeit limited, at the level of the junctions between adjacent longitudinal elements. We can thus obtain deviations between the axes of two adjacent individual reinforcements, which can be of the order of 5°, which remains small but which, given the number of longitudinal elements, can result in a significant curvature of the pipe in its entirety. Such freedom, even if slight, makes it possible to better tolerate, or even resist, some of the constraints imposed by driving.

[0038]Preferably, the fixing assembly comprises a first peripheral element with means of fixing to the supporting structure, for example cable clips and possibly stiffeners.

[0039] This is an example of fixing the longitudinal elements to the supporting structure: cable clamps thus make it possible to securely mount the assembly for fixing the longitudinal element to the cables, and the stiffeners. make it possible to reduce the curvature of the cables at the exit of the cable clamps in order to limit damage to the cables.

[0040]Preferably, the fixing assembly also comprises a second peripheral element mounted between the individual frame and the first peripheral element, and mounted on the first peripheral element by second pivot connections, preferably two diametrically opposed, the second connections pivot between the first peripheral element and the second peripheral element and the first pivot connections between the second peripheral element and the individual frame being distributed over the periphery of the longitudinal element.

[0041]In this case, two pivot axes are provided for the individual frame relative to the supporting structure. A first axis is obtained by two pivot connections mounted between the second peripheral element and the first peripheral element secured to the supporting structure, and a second axis, preferably perpendicular to the first, is obtained by two pivot connections mounted between the individual frame and the second peripheral element. We then obtain a degree of freedom between two adjacent individual frames which is more important and which allows an orientation, albeit weak, in any direction of space in order to respond to the external constraints which apply to the pipe.

[0042]Preferably, the individual frame comprises an upper end portion and a lower end portion, the diameter of the inner peripheral surface of the upper end portion is greater than the diameter of the outer peripheral surface of the portion lower end portion, the upper end portion extending, longitudinally, beyond the wall forming a pipe section so as to be able to surround the outer peripheral surface of the lower end portion of an adjacent longitudinal element in order to form , with said outer peripheral surface of the lower end portion of the adjacent longitudinal element, two cylindrical bearing surfaces facing each other between which the sealing means are arranged.

[0043] According to this embodiment, two adjacent individual frames are provided to fit partially into each other. In order to maintain a certain freedom of pivoting between said two adjacent individual frames, the interlocking between the two individual frames is not done by force but on the contrary with a significant clearance between the two facing surfaces. However, the two facing surfaces can then form bearing surfaces for the sealing means which are then easier to install.

[0044] Preferably, the sealing means comprise flexible strips and/or one or more water-inflatable seals and/or one or more bellows seals. The joints are designed to allow both a certain freedom of movement of the individual reinforcements adjacent to each other, but also to resist the different pressures experienced as the depth increases. For this purpose, several types of seals can be combined in order to limit leaks between the inside and outside of the pipe. In fact, such leaks would heat up the water conveyed inside the pipe and therefore reduce the efficiency of the system.

[0045]Preferably, the device also comprises a ballast mounted at a lower end of the supporting structure. The ballast makes it possible to avoid raising the lower end of the pipe too much, in order to try to pump the water to the greatest depth, and therefore the coldest possible.

[0046]Preferably, the device also comprises a support on which the supporting structure is retained by an upper end. The support may be a platform or a boat, or a part of a platform or a boat.

[0047]Preferably, the support comprises a means for driving the supporting structure, for example at least two, or even three or more, winches preferably without lateral offset.

[0048]Preferably, the support comprises at least one pump in fluid communication with the interior of the pipe and opening at a determined distance below the water level in the pipe at rest, for example between 3 and 4 meters below the water level at rest.

[0049]The pump makes it possible to circulate the water inside the entire pipe, by sucking only the surface part. By maintaining a height difference between the level inside the pipe and the level of the sea or lake, we automatically obtain a circulation of water towards the inside of the pipe, i.e. a cold water inlet. . ’ ·

[0050]Alternatively, the device may comprise at least one pump mounted on a lower part of the pipe and/or the supporting structure. In this case, the water is drawn inside the pipe by a pump located at the bottom thereof and which causes the circulation of cold water towards the inside and towards the top of the pipe.

[0051]Preferably, the pipe has a total length greater than or equal to 150 meters, preferably greater than or equal to 500 meters, preferably greater than or equal to 1,000 meters, and an internal diameter greater than or equal to 1 meter, preferably greater than or equal to 2 meters, preferably greater than or equal to 4 meters.

Preferably, the pipe comprises a number of longitudinal elements greater than or equal to 10, preferably greater than or equal to 25, plus 20 preferably greater than or equal to 40.

Brief description of the drawings

[0053][Fig. 1] Figure 1 schematically represents a device for pumping water at great depth according to the invention;

[0054][Fig. 2] Figure 2 shows, in perspective, a longitudinal element according to the present invention;

[0055][Fig. 3] Figure 3 is a schematic sectional representation of the upper end of the longitudinal element shown in Figure 2;

[0056][Fig. 4] Figure 4 is a schematic sectional representation of the fixing of a longitudinal element on the supporting structure and its junction with the adjacent longitudinal element;

[0057][fig. 5] Figure 5 schematically represents a first example of circumferential prestressing means according to the present invention, and

[0058][Fig. 6] Figure 6 schematically represents a second example of circumferential prestressing means according to the present invention.

Description of embodiments

[0059] Figure 1 schematically illustrates a device 1 for pumping water at great depth according to the present invention. The device 1 comprises a support 2 on which a pipe 4 is mounted via a supporting structure 6. More precisely, the pipe 4 is formed of a plurality of longitudinal elements 8 each comprising a pipe section, or wall, 10. The pipe 4 is therefore formed by the assembly of the different pipe sections 10 of the different longitudinal elements 8.

The supporting structure 6 may comprise one or more cables 11, preferably three, or even more, cables 11, for example made of steel, distributed around the pipe 4. The use of cables makes it possible to have a supporting structure 6 which can be wound, for example on a reel, for storage and transport: we then obtain a supporting structure 6 that is compact and easy to handle, despite its length.

[0061] As illustrated in Figure 2, each longitudinal element 8 comprises a pipe section, or wall, 10, for example cylindrical in shape, an individual frame 13 and a fixing assembly 12 arranged in the upper part of the individual frame 13. Furthermore, in order to ensure the sealing of the pipe 4, the longitudinal elements 8 are connected together by sealing means 14.

[0062] The pipe section 10 is. a rigid section, for example made of composite material, steel or aluminum alloy. Preferably the section 10 is made of steel in order to have high mechanical strength for a low weight. In order to further lighten the section 10, it may include a steel wall of lighter thickness reinforced by one or more hoops 16 extending on the outer peripheral surface of the section 10 and distributed over the length of the section 10. Furthermore, in order to limit thermal losses between the cold water circulating inside the pipe 4 and the hot water located around the pipe 4, one or more longitudinal elements, for example those located on the side of the surface of the water, can also include a coating of thermal insulating material, for example of nanoporous material. The water pumped from great depths can thus remain cold during its rise along pipe 4, which increases the efficiency of the thermodynamic cycle in which it is used.

[0063] As illustrated in Figure 3, the fixing assembly 12 makes it possible to fix the longitudinal element 8, and more particularly the individual reinforcement 13, on the cables 11 of the supporting structure 6. Thus, the weight of the pipe 4 is carried regularly on the supporting structure 6, so as to avoid weight constraints between the different longitudinal elements 8 between them, and also allow, as described below, a certain mobility of the longitudinal elements 8 between them.

[0064]Thus, the fixing assembly 12 comprises a first peripheral element 18 which is fixed on the supporting structure 6. The first peripheral element 18 can thus have an annular shape extending around the individual frame 13, with means for fixing to the supporting structure 6. The fixing means can for example be notches configured to cooperate with a cable clamp 20 so as to securely mount the first peripheral element 18 on the cables 11 of the supporting structure 6 (see figure 4); More precisely, the notches may comprise a semi-cylindrical recess and the cable clamp 20 may also have a semi-cylindrical recess so that, when the cable clamp 20 is mounted in the notch, for example by screws 22, we obtain a cylindrical hole in which the cable 11 of the supporting structure 6 is enclosed. The first peripheral element 18 is therefore mounted integrally with the supporting structure 6.

[0065] Stiffeners 24 can also be provided on the first peripheral element 18, in continuity with the fixing means 20, in order to limit the curvature of the cable 11 at the outlet of the fixing means 20. Thus, the stiffener 24 can be a elongated element, for example in the form of a cone, one end of which is mounted on the first peripheral element 18 and the other end of which is in contact with the cable it. The stiffener 24 can deform between its two ends, but less pronounced than the cable 11 of the supporting structure 6, in order to always leave the cable 11 a certain flexibility while limiting the curvature thereof in the immediate vicinity of the means of fixation. This limits degradation of the cable 11.

The fixing assembly 12 may also comprise a second peripheral element 26 mounted between the individual frame 13 and the first peripheral element 18. The second peripheral element 26 may thus have the shape of a torus, for example hollow, extending around the individual frame 13. The second peripheral element 26 makes it possible to make the mechanical connection between the individual frame 13 and the first peripheral element 18, while allowing rotations of the individual frame 13 relative to the first peripheral element 18 in any direction of space.

[0067]To this end, the second peripheral element 26 comprises two first pivot connections 28 mounted along a first pivot axis which is illustrated horizontally in Figure 3. The two first pivot connections 28 are mounted between the individual armature 13 and the second peripheral element 26: they allow a degree of freedom in rotation of the individual armature 13 relative to the second peripheral element 26 along the first pivot axis.

[0068] Furthermore, the second peripheral element 26 also comprises two second pivot connections 30 mounted along a second pivot axis which is illustrated vertically in Figure 3. The two second pivot connections 30 are mounted between the second peripheral element 26 and the first peripheral element 18, with a second pivot axis which is perpendicular to the first pivot axis while remaining in a plane substantially perpendicular to the general longitudinal direction of the pipe 4, that is to say in the plane of the first peripheral element 18. Thus, the second pivot connections make it possible to have a degree of freedom in rotation of the second peripheral element 26, and therefore of the individual armature 13, relative to the first peripheral element 18, along the second pivot axis.

[0069JII is thus possible to have a rotation of the individual armature 13, and therefore of the pipe section 10, relative to the first peripheral element 18, in any direction of space included in the plane of the first peripheral element. It is then possible for pipe 4 to deform, although with a limited amplitude, depending on the constraints exerted by the current.

[0070]In order to limit the thermal losses between the different longitudinal elements 8 between them, sealing means 14 are arranged between the pipe sections 10. For example, the individual reinforcements 13 of the longitudinal elements 8 can comprise a portion of upper end 32 and a lower end portion 34, the upper end portion 32 having a diameter of an inner peripheral surface which is greater than the diameter of an outer peripheral surface of the lower end portion 34. The portion upper end extends, longitudinally, beyond the pipe section 10 so as to be able to surround the outer peripheral surface of the lower end portion 34 of an adjacent longitudinal element 8. The interior peripheral surface of the upper end portion 32 and the exterior peripheral surface of the adjacent lower end portion 34 form two cylindrical surfaces facing each other between which seals can be mounted, for example flexible slats. The flexible lamellas make it possible to limit the circulation of water between the interior and exterior of the pipe 4, while allowing the two adjacent individual armatures 13 to have a certain degree of freedom in rotation relative to the 'other. In particular, the individual reinforcement 13 of the upper longitudinal element 8 is not mounted by force in the upper end portion 32 of the lower longitudinal element 8.

[0071] We thus obtain a pipe 4 which can be particularly long, while having a fixed diameter thanks to the rigid pipe sections 10.

[0072]At its lower end, the device 1 also comprises a ballast 40. The ballast 40 has the general shape of a hollow cylinder. The hollow cylinder is closed at its lower end and open at its upper end so as to be able to put more or less ballast elements there depending on the configuration of the device. The ballast 40 is mounted on the device 1 thanks to the cables 11 of the supporting structure 6 which are fixed to the upper end of the hollow cylinder. The ballast therefore makes it possible to tension the supporting structure 6 in order to pump the water to the greatest possible depth.

[0073]The lower end of ballast 40 may also have a thinner thickness, in order to facilitate the flow of cold water towards the interior of pipe 4.

[0074]At its upper end, the device 1 also comprises a pipe head 42. The pipe head 42 allows the connection between the pipe 4 and the support 2 in which the cold water is pumped. The pipe head thus comprises a pipe section 10 and a fixing assembly 12 which is not necessarily arranged at one of the ends of the section 10 but which makes it possible to fix the section 10 to the supporting structure 6 like the sections of the longitudinal elements 8.

[0075]Furthermore, the driving head 42 also comprises a pumping zone 44 which can be in the form of a hollow cylinder whose internal diameter corresponds to the external diameter of the fixing assembly 12 of the driving head 42 , In particular, the fixing assembly 12 is positioned in a sealed manner in the pumping zone 44, in order to prevent the water surrounding the pipe head 42 from infiltrating into the pumping zone 44.

The pumping zone 44 extends above the upper end of the section 10 and above the water level at rest. This prevents water from entering the pumping zone 44 from above, for example under the effect of swell.

[0077] Inside, the pumping zone 44 also includes a connection opening with pumping means 46. The connection opening is arranged above the fixing assembly 12 and below the level of the water at rest. The distance between the connection opening and sea level defines the maximum height difference ΔΗ that can be obtained when pumping the water leaving pipe 4 into pumping zone 44. Once the cold water has been pumped by the pumping means 46, this is sent into the thermodynamic cycle ίο as a cold source, while the difference in height created by the pumping means 46 in the pumping zone 44 causes the circulation of the water on the entire height of pipe 4, in order to continue to supply the pumping zone 44 with cold water.

[0078] The pipe 4, with its ballast 40 and its driving head 44, are mounted on the support 2 which supports the supporting structure 6. More particularly, the cables 11 of the supporting structure 6 are unwound from reels 48 arranged on the support 2 and driven by winches 50, in particular vertical winches without lateral offset, up to a return pulley 52. Such winches are known and in particular marketed by the company Imeca. The vertical winches 50 without lateral offset allow the use downstream of return pulleys 52 which are fixed on the support, and which can therefore lower the supporting structure 6 from the same point. Such a configuration facilitates in particular the installation of pipe 4 as described below.

[0079]In order to improve the mechanical strength of each section of pipe 10, 25 in particular when the depression is created inside the pipe 4 to suck up cold water, the longitudinal elements 8 can also include prestressing means of the pipe section 10. Such means of.

prestressing therefore aims to create, in the pipe section 10, an initial centrifugal stress which will be compensated, during operation, with the centripetal stress created by the internal suction of the pipe 4.

[0080]For this purpose, the individual reinforcement 13 of the longitudinal elements 8 comprises different means intended to serve as a support for the prestressing means. The individual frame 13 can thus comprise longitudinal means 54, for example cylindrical tubes, extending between the upper end portion 32 and the lower end portion 34 of the individual frame 13. The longitudinal means 54 are preferably uniformly distributed around the perimeter of the pipe section 10, and can be three, four, five or even six in number. The longitudinal means 54 make it possible to maintain fixed and stable the distance between the lower end portion 34 and the upper end portion 32 of the individual frame 13. The longitudinal means 54 can also serve as a support for peripheral supports and /or prestressing means.

[0081]Thus, the individual armature 13 may also include peripheral means 56, for example in the form of toroids, extending around the pipe section 10, in planes parallel to those of the end portions 32, 34. The peripheral means 56 are in particular mounted on the longitudinal means 54, for example pass through the longitudinal means 54, to surround the pipe section 10. The peripheral means 56 are preferably uniformly distributed between the lower end portion 34 and the portion d upper end 32 of the individual frame 13, and can be two, three, four or even five in number. The peripheral means 56 make it possible to serve as a support for prestressing means.

[0082] Thus, the individual reinforcement 13 with its longitudinal means 54 and peripheral means 56 form a sort of cylindrical cage, or crinoline, surrounding the pipe section 10 and on which it is then possible to mount prestressing means to pre -constrain the pipe section 10.

[0083]The longitudinal element 8 may comprise circumferential prestressing means 58, and longitudinal prestressing means 60 (see Figure 4).

[0084]The longitudinal prestressing means 60 make it possible to create a tensile stress which extends in the axial direction of the pipe section ι

10. The longitudinal prestressing means 60 therefore make it possible to stretch the pipe section 10 in the direction of its length.

[0085]For this purpose, the pipe section 10 can already comprise, at a first end, for example at the upper end, a peripheral flange 62 5 intended to come to rest on a shoulder 64 of one of the portions of end of the individual frame 13, for example of the upper end portion 32. The peripheral flange 62 thus makes it possible to block the pipe section 10 on the end portion of the individual frame 13, and prevents the section of pipe 10 to slide inside the individual armature 13. The section of ίο pipe 10 is also mounted, by its second end opposite the first end, at the other end portion of the individual armature 13, for example at the lower end portion 34, by a longitudinal prestressing means 60 making it possible to adjust the distance between the end of the pipe section 10 and the end portion of the individual reinforcement 13.

[0086]The longitudinal prestressing means 60 can thus be a tie rod engaging, on one side, in a thread of the pipe section 10 and, on the other side, with a bolt positioned abutting on the end portion of the individual reinforcement 13. Thus, by reducing the distance between the end of the pipe section 10 and the end portion of the individual reinforcement 13, for example 20 by screwing the tie rod into the thread of the pipe section 10 or tightening the bolt on the tie rod, it is possible to stretch the pipe section 10 in its axial direction.

[0087] Thanks to the longitudinal means 54 of the individual reinforcement 13 and the longitudinal prestressing means 60, it is therefore possible to create a longitudinal, or axial, prestress in the pipe section 10.

[0088]The circumferential prestressing means 58 make it possible to create a tensile stress which extends in the centrifugal, or radial, direction of the pipe section 10. The circumferential prestressing means 58 therefore make it possible to stretch the pipe section 10 circumferentially.

[0089]For this purpose, circumferential prestressing means 58 are mounted, by a first end, on the peripheral means 56 of the individual armature 13, and, by a second end opposite the first end, on the pipe section 10. The circumferential prestressing means 58 are also distributed around the periphery of the pipe section 10. The circumferential prestressing means 58 make it possible to adjust the distance between the peripheral surface of the pipe section 10 and the peripheral means 56 of the armature individual 13.

[0090] Figures 5 and 6 illustrate two embodiments of a peripheral prestressing means 58 produced in the form of a turnbuckle. The peripheral prestressing means 58 thus comprise a body in two parts: a first part 66 secured to the pipe section 10, and a second part 68 secured to the peripheral means 56. An elastic means 70, such as spring washers, is positioned between the two parts 66, 68 of the body of the peripheral prestressing means 58, in order to be able to modify the spacing between the two parts 66, 68 of the body according to the amplitude of the forces exerted between the two parts 66, 68 of the body.

[0091]Thus, by reducing the distance between the two parts 66, 68 of the body of the peripheral prestressing means 58, it is possible to stretch the pipe section 10 in its radial direction. Furthermore, in order to prevent the prestressing exerted by the peripheral prestressing means 58 on the pipe section 10 from being too localized and locally damaging the pipe section 10, the peripheral prestressing means 58 may comprise a means of attaches to the pipe section 10 having a determined minimum surface area of contact with the pipe section 10.

[0092]Thanks to the circumferential means 56 of the individual reinforcement 13 and the peripheral prestressing means 58, it is therefore possible to create a centrifugal, or radial, prestress in the pipe section 10, which will directly oppose the stresses centripetal due to the depression created inside pipe 4, in operation.

[0093] We then obtain in a simple and rapid manner a cold water pumping pipe at great depth which can measure several hundred meters long. In particular, the device described is easy to install, and makes it possible to control the flow of cold water by the pumping means, thanks to the constant diameter of the pipe.

Claims (10)

[Claim 1] Device (1) for pumping water at great depth, comprising a plurality of assembled longitudinal elements (8) 5 between them to form a pipe (4) inside which the pumped water circulates at great depth, in which each longitudinal element (8) comprises a wall (10), for example of thickness less than or equal to 5cm , forming a section of said pipe (4), said wall (10) being · prestressed in traction, for example longitudinally and/or 10 circumferentially, when the water is not pumped into the pipe (4). [Claim 2] Device (1) according to the preceding claim, in which said prestress, for example radial, is chosen substantially greater than or equal, in amplitude, to the depression created inside for pumping water with the device ( 1), so as to balance the pressures exerted on the wall (10) when water is pumped with the device. [Claim 3] Device (1) according to any one of the preceding claims, in which each longitudinal element (8) comprises a 20 individual frame (13), for example in the form of a crinoline, said wall (10) being mounted on, and in particular inside, the frame (13). [Claim 4] Device (1) according to the preceding claim, in which the reinforcements (13) are configured to connect together in a sealed manner, said longitudinal elements (8), for example comprising end portions (32, 34 ) with sealing means (14) configured to cooperate with the end portions (32, 34) of the adjacent reinforcements (13). [Claim 5] Device (1) according to claim 3 or 4, in which the wall (10) of each longitudinal element (8) is pre-stressed relative to the reinforcement (13). s [Claim 6] Device (1) according to the preceding claim, comprising circumferential prestressing means (58) of the wall, for example turnbuckles, and/or longitudinal prestressing means (60) of the wall, for example tie rods , said circumferential and/or longitudinal prestressing means being mounted between the frame (13) and the wall (10). [Claim 7] Device (1) according to the preceding claim, in which the circumferential prestressing means (58) comprise an elastic means (70), for example spring washers mounted in the 15 turnbuckles, to allow deformation of the wall ( 10) pre-tensioned, when water is pumped with the device (1). [Claim 8] Device (1) according to any one of the preceding claims, in which the armature (13) comprises at least two, of 20 preferably three, longitudinal means (54), for example bars, connecting together the end portions (32, 34) of the frame (13), and at least two, preferably four or more, peripheral means ( 56), for example tori, connecting the longitudinal means (54) to each other. 25 [Claim 9] Device (1) according to any one of the preceding claims, also comprising a supporting structure (6), and in which the longitudinal elements (8) are individually mounted integrally on the supporting structure (6), of preferably by the upper or lower end of their frame (13). [Claim 10] Device (1) according to any one of the preceding claims, in which the pipe (4) has a total length greater than or equal to 150 meters, preferably greater than or equal to 500 meters, preferably greater than or equal to 1,000 meters, and an internal diameter greater than or equal to 1 meter, preferably greater than or equal to 2 meters, preferably greater than or equal to 4 meters.