FRESHWATER TANK FLOATING AT SEA

Abstract

Freshwater storage system at sea, consisting of a bottomless cylinder containing a piston fitted with a sliding seal. The freshwater to be stored is located above the piston, the seawater below. A float attached to the upper part of the cylinder ensures its position relative to sea level, the cylinder never being empty. Figure for the Abstract: FIGURE 1

Description

Title of the invention: FRESHWATER TANK FLOATING AT SEA

[0001] Agriculture generally requires significant irrigation, corn being a very good example. When periods of drought occur, in regions such as western France, irrigation by pumping from groundwater or small streams becomes difficult. It would be necessary to have storage basins for the water available in winter. For example, if, on a cultivated area of ​​10,000 km2, it is estimated that, for a period of one month, there is a need for a water depth of 100 mm and that this water must be supplied by storage, the total quantity to be stored is one billion cubic meters. In lowland areas such as western France, the reasonable average depth for retention basins is approximately 10 m. The total surface area of ​​these basins would therefore need to be 100 square kilometers, which poses environmental and land availability problems.The present invention aims to install floating freshwater storage tanks at sea, as close as possible to the land to be irrigated. For example, the quantity of water mentioned above can be obtained with 500 cylinders of 120 meters in diameter and 200 meters deep, non-limiting example. Placed vertically, these tanks would form a structure 200 m high which would present a large wind resistance with empty tanks and complications for filling. According to the present invention, the tanks will always be submerged, protruding above sea level by about ten meters, for example non-limiting. Thanks to a movable piston inside, they will always be full, either with sea water, the piston being in the high position, or with fresh water, the piston being locked in the low position. The piston constitutes a watertight barrier between fresh water and sea water.The density of sea water being on average 1.03, when in a cylinder the piston is in the low position, filled with fresh water, therefore, for a cylinder of 200 m depth cited as an example, the level of fresh water must exceed by approximately 6 m the level of the sea so that at the base of the cylinder there is hydrostatic equilibrium on each side of the piston between fresh water and sea water. The piston must obviously have sliding sealing devices. To do this, the best known systems are: O-rings, lip seals, generally composed of several plates.

[0002] of elastomer and finally the membranes turning inside out like a glove, like those developed by the company "le Joint Français" under the name of "Bellofram membrane", (for mainly pneumatic applications). A cover at the top of the cylinder will prevent contamination of the stored fresh water by the salt spray. To ensure guidance and prevent jamming, according to the present invention, inside each cylinder, the piston is secured to a structure provided with rows of rollers, at the bottom and at the top, moving along the generators. Since the hydraulic pressures are relatively low, the walls of the cylinders may be relatively thin, possibly reinforced by external skeletons. A cylinder such as described above, having no bottom, does not float. It must therefore be supported by a float arranged around its upper part, ensuring a determined position relative to sea level, whatever the position of the piston and the nature of the filling, sea or fresh water. This float may have a hexagonal external shape. Then, such cylinders, placed side by side, will form a honeycomb structure. [Fig. 1] is a vertical section of the invention, piston in the high position. [Fig.2] is the same with the piston in the low position. [Fig.3] is a detailed section showing a sliding O-ring. [Fig.4] is a detailed section showing a lip seal. [Fig.5] is a section of the invention showing a cylindrical membrane fixed on the piston on the one hand and on the top of the cylinder on the other hand, the piston being shown in an intermediate position. [Fig.6] is likewise a section, the said membrane being fixed on the piston on the one hand and on the bottom of the cylinder on the other hand. With reference to [Fig.l], a tank comprises a bottomless cylinder (1), provided with a cover (2), supported by a float (3) and enclosing a sealed piston (4), shown in the high position in this figure. The cylinder (1) is then filled with seawater below the piston (4) and empty above. U-shaped side members (5) extend the cylinder (1) upwards.They are intended to constitute rolling paths for a row of rollers (6) placed at the top of poles (7), integral with a structure linked to the piston (4). To ensure effective guidance, the number of these side members (5) and poles (7) must be equal to or greater than three.

[0003] preferably six, these figures being non-limiting. Another row of rollers (6) is integral with the piston (4) and placed just above it, the distance between these two rows of rollers (6) being determined to ensure guidance without jamming, a quarter of the diameter of the cylinder (1) for example non-limiting. The poles (7) pierce the cover (2) through orifices (8) placed at the feet of the side members (5) and provided with articulated caps (9) which close under the action of a spring when the assembly, piston (4), poles (7) with rollers (6), descends back inside the cylinder (1), by the fact of gentle filling. Guide rails (10), placed on the inner surface of the cylinder (1), in the part which is never filled with water, allow the rollers (6), at the tops of the poles (7), to always engage in the U of the side members (5), even in the case where the piston (4) has undergone, during its movement, a slight rotation.The cylinder (1) protrudes above sea level by the size necessary to accommodate the height of fresh water ensuring hydrostatic equilibrium. when this cylinder (l) will be filled with fresh water, the piston (4) then in the low position, where it is blocked by a mechanical lock. In (11) is shown the fresh water filling orifice. With reference to [Fig.2], with the piston (4) in the low position, the cylinder (l) being filled with fresh water above the piston (4). This figure shows that the level of the fresh water is located above the level of the sea water, to ensure, due to the lower density of the fresh water, the hydrostatic balance at the bottom of the cylinder (1), on either side of the piston (4). With reference to [Fig.3], it is shown, in section, a detail of the periphery of the piston (4) with a groove (12) containing an O-ring (13) pushed by a spring, or a spring assembly (14). Several superimposed O-rings are possible. Just below the groove (12), a second groove (15) receives a spring-loaded scraper segment (16) or spring assembly (17).The scraper segment (16) has a sharp edge (18) distant from the wall of the cylinder (1) by a few tenths of a millimeter, in a non-limiting manner. Indeed, when the piston is in the high position, the cylinder (1) is filled with sea water and shellfish can thrive on its wall if the piston (4) remains stationary for a long time. Their shell is very abrasive and could damage the seal (13). With reference to [Fig.4] a detail of the periphery is shown in section.

[0004] of the piston (4) provided with a lip seal comprising a stack (19) of elastomer sheets. In the same way as for [Fig.3], a scraper segment (16) cleans the cylinder (1) during the descent of the piston (4). With reference to [Fig.5], a sectional view shows a flexible cylindrical membrane (20) fixed on the top of the cylinder (1) on the one hand and on the piston (4) on the other hand, making it possible to isolate the fresh water from the sea water during the movement of the piston (4). It should be noted that the rollers (6) then roll on the wall of the membrane (20) in contact with the fresh water. In this figure the piston (4) is shown in an intermediate position. With reference to [Fig.6], a sectional view shows the flexible cylindrical membrane (20), fixed on the bottom of the cylinder (1) on the one hand and on the piston (4) on the other hand. As in [Fig.5], the piston (4) is shown in an intermediate position towards the middle of the cylinder (1).As mentioned above, several cylinders, objects of the invention, can be assembled in a honeycomb structure. If the bottom of the cylinders is sufficiently close to the seabed, the assembly can be rigidly fixed to this bottom. If, on the contrary, the depth is greater, an anchoring system must be provided. To be closer to the coast, if there is relatively little bottom, it may be interesting to place, rigidly installed, sets of smaller numbers of cylinders, shallower (50 m for example, non-limiting). To protect all these installations, a dike, fixed or floating, can advantageously be placed, on the seaward side, to break the swell. The filling, in winter, of such a water reserve, can be done using "pipelines" supplied from rivers, or, preferably in winter, from water tables. It can also be done. by very large tankers. The capacity of oil tankers had been limited to 200,000 t to minimize damage, as much as possible, in the event of a shipwreck. In the case of fresh water transport, tankers of 500,000 t or more can be considered. These giant tankers with deep draft could refuel in the deep mouths of very large rivers such as the Amazon or the Congo. These vessels could be mainly sail-powered with thermal engines ensuring maneuvering.

Claims

Claims

1. A tank for storing fresh water at sea, comprising a bottomless cylinder (1), provided with a cover (2), supported by a float (3) containing a sealed piston (4), which can rise or fall, with the sea water under its lower face and the fresh water to be stored on its upper face, further comprising rows of guide rollers (6), the first row just above the piston (4), another at the top of poles (7), further comprising, secured to the upper end of the cylinder (1)) U-shaped cross-section longitudinal members (5) serving as a rolling path for the rollers (6) at the top of the poles (7), when the piston moves in the upper part of the cylinder (1), further comprising guide rails (10) thus allowing the rollers (6) at the top of the poles (7) to always engage in the longitudinal members (5), in the event that the piston (4) has made a slight rotation,characterized by the fact that the distance between the two rows of rollers (6) is close to a quarter of the diameter of the cylinder (1).,

2. Fresh water storage tank at sea according to claim 1), characterized in that, to remove abrasive shells, during the downward movement of the piston (4), a scraper segment (16) is arranged.

3. Fresh water storage tank at sea according to claims 1) and 2), characterized in that it comprises an O-ring (13) placed in a groove (12) of the piston (4).

4. Fresh water storage tank at sea according to claims 1) and 2) characterized in that it comprises in the groove (12) of the piston (4) a lip seal (19) composed of elastomer sheets.

5. Fresh water storage tank at sea according to claim 1), characterized in that it comprises, to separate the fresh water from the sea water, a flexible cylindrical membrane (20) fixed on the upper part of the cylinder (1) on the one hand and on the piston (4) on the other hand.

6. Fresh water storage tank at sea according to claim (1), characterized in that it comprises, to separate the fresh water from the sea water, a flexible cylindrical membrane (20) fixed on the lower part of the cylinder (1) on the one hand and on the piston (4) on the other hand.

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