GB2401405A

GB2401405A - A tidal powered device for pumping fluid

Info

Publication number: GB2401405A
Application number: GB0409720A
Authority: GB
Inventors: Thomas Adamson
Original assignee: T GEN SERVICES Ltd
Current assignee: T.GEN SERVICES LIMITED
Priority date: 2003-05-01
Filing date: 2004-05-04
Publication date: 2004-11-10
Anticipated expiration: 2024-05-04
Also published as: GB0409720D0; GB2401405B; GB0309964D0

Abstract

A tidal powered device 1 comprises a first buoyant member 2 connected by a connecting element 4 to a second member 5 which pumps a second fluid in a chamber 7. Movement of the first member 2 causes pumping of the second fluid relative to the chamber. The second member 5 may be a diaphragm, attached to an interior wall of the chamber and dividing it in two. The device may be supported by structure 12, secured to the sea floor and having a telescopic shaft 9 which guides the movement of the connecting element 4. The device may be used to pump water for electricity generation or to a desalination plant.

Description

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Introduction

s This invention relates to a device for pumping a fluid. In particular it relates to a device which may be used for generating electricity by harnessing tidal power.

There is an increasing demand for energy from renewable sources, an example of which includes hydro-electric power. However the construction of installations for lo harnessing this renewable energy is often itself environmentally damaging. For example, the development of such hydroelectric schemes has met with much resistance as it often requires existing valleys to be flooded to produce the necessary head of water.

Furthermore, extensive regions of the world, particularly the Third World, are surrounded by seawater, but lack of source of potable water. The desalination of water has hitherto largely been dependent on fossil fuels as the power source, but the rising cost and increasing scarcity of these fossil fuels renders them substantially unavailable to poorer countries.

Desalination of seawater by wave-powered reverse osmosis is known. The pressure at one side of a filtering membrane forces the contaminated water through to the other side, cleaning the water as it does so.

Statements of Invention

According to a first aspect of the present invention there is provided a device comprising; a first member configured to be buoyant in a first fluid; a connecting element; a chamber suitable for containing a second fluid; c c c c C 1 C À C C 1 C C 1 C. C C À c 1 C C C C a second member connected to said buoyancy member by said connecting element; wherein, movement of the first member causes pumping of said second fluid relative to said chamber.

The invention provides a device which harnesses the power generated by tidal oscillations.

In a preferred embodiment of the present invention the chamber is manufactured from lo reinforced concrete. The size of the chamber can vary considerably and is dependent on whether the device is to be located in the sea for harnessing tidal power, or whether it is scaled-down for use in controlling the flow of other fluids. When used in the sea, the device would have a large enough mass to be able to be positioned on the sea bed without the need for any securing means. Preferably some 95% of the working structure of the device is submerged. However, smaller scale devices may require anchoring. This anchoring means may be in the form of an anchoring shaft which extends through the base of the chamber and which is anchored to the sea bed.

This anchoring shaft may form the lower part of a telescopic pair of shafts, wherein the connecting element forms a hollow upper shaft that slides over said lower shaft. It is this connecting element which transfers the tidal force to the diaphragm. The two parts of the telescopic shaft are preferably manufactured from stainless steel. When the telescopic shaft is shortened by one piece sliding inside the other, this hollow tube then becomes a very high pressure pump. This increased pressure can be used, for 2s example, in lifting the pressure in a pipe-network which transports the pressurised water to its point of use or to lift water to a high head and supply water to a height not possible by other pressures.

The first member is configured to be buoyant either at the surface of a fluid or when submerged within a fluid. In a further preferred embodiment of the present invention the first member is a pontoon which is buoyant at the surface of the sea. There are a number of advantages associated with the use of pontoons. When the pontoons are located at the surface of the sea their vertical position relative to the chamber would not only be effected by tidal oscillations but also by the motion of the waves.

1 ' .. r 4 It6 À 6. À 1 6 4 ' Furthermore, if enough large pontoons were placed where there is coastal erosion this could control the surges and therefore protect the coast-line. Another advantage would be to place the pontoons so they would form a floating harbour where ships and yachts would be protected from the elements and still be able to put to sea even with s deep droughts. Additionally, when the pumps are placed in close proximity with each other, then fish would be encouraged to breed within the field of structures. If the fields of pumps are laid in directional strings some 600 fit (180 metros) or more in width and some 3 kilometres in length having substantial pontoons operating on the surface and placed close together, a steel runway could be incorporated and thereby lo produce a very large aircraft carrier when laid in North- South direction and crossed by another string (runway) West-East. This would provide a perfect airport all floating a considerable distance from shore and producing all its own power and water plus no land forcibly obtained, to say nothing of the objections of the locals on shore against earth bound airports expansions.

When pontoons are used, a weight which is coupled to the pontoon, for example by chains, has to be placed at the top of the connecting element in order to produce enough force on the downward stroke.

an alternative embodiment, where the area for the location of these devices comes within the visible environmental objectional districts, the buoyant first member is submerged. In such a situation it is trimmed to neutral buoyancy and thus is retained at a predetermined depth within the sea, rising and falling with the tidal oscillations but remaining submerged. 2s

The first member is connected, via the connecting element to the second member. It will be appreciated that whilst the second member can form a wall of the device it is preferably located within the chamber. Preferably this second member is a diaphragm.

More preferably still this diaphragm is fixedly attached to the inner surface of the chamber, thereby dividing the chamber into at least an upper and lower sub-chamber.

The fact that the diaphragm is fixedly attached in this way has a significant technical advantage in that the movement of the diaphragm against the side of the chamber does not involve a sliding seal. The arrangement provided by the invention does not therefore result in any leakage (particularly if sand/grit from the sea bed becomes À À c À c c c disposed between the moving parts) between the diaphragm and the wall of the chamber any such leakage would not only reduce the efficiency of the pump but also increase the maintenance necessary. In the device disclosed in the present invention, the diaphragm is sealed around the periphery to the inner wall of the chamber, thus there is no sliding contact and no leakage pressure possible between the diaphragm and the inner wall. Each sub-chamber can house a separate fluid and thus the device can be considered to comprise two separate pumps.

In a further preferred embodiment, the diaphragm is secured, preferably sealingly lo secured, to the connecting element preferably by being sandwiched between two closely disposed plates provided at the lower end of the connecting element.

During the operation of the device in the sea the diaphragm draws sea water into the chamber under vacuum and forces it out under pressure on the reverse stroke. This pressure is applied by the weight of the first member under gravity in the down-stroke and by the buoyancy of the first member on the upstroke.

In yet a further preferred embodiment of the present invention the device comprises a support structure, wherein said structure comprises a plurality of vertical supports. A principal function of these vertical supports is to guide the vertical movement of the buoyant first member.

Preferably the first member is moveable in response to changes in the level of a first liquid. Preferably the first and second fluids are the same. Even more preferably said first and second fluids are liquids. More preferably still the first and second fluids are seawater. The fluid flow relative to the chamber is controlled by valves. Preferably at least one two-way valve is located in each of the lower and upper parts of the chamber. Preferably still these valves are manufactured from stainless steel.

so The pressurised water that is discharged from the device is transported to its point of use, for example an electricity generator or desalination plant. This transport is preferably by a pipe-line. This pipe-line may link a plurality of the devices.

:: ::e.:e::: .e.e Id: c If the pressurised water is not required immediately then it may be stored for use at a later time by pumping it into large hydraulic chambers, similar to those in which gas is stored.

s According to a second aspect of the present invention there is provided a method for generating electricity comprising the steps of; (a) providing a device comprising; a first member configured to be buoyant in a first fluid; a connecting element; l o a chamber suitable for containing a second fluid; a second member connected to said buoyancy member by said connecting element; wherein, movement of the first member causes pumping of said second fluid relative to said chamber.

(b) locating the device in a first fluid; (c) supplying the water pumped out of the device in a) to a generator.

According to a third aspect of the present invention there is provided a method for desalinating water comprising the steps of; (a) providing a device comprising; a first member configured to be buoyant in a first fluid; a connecting element; a chamber suitable for containing a second fluid; a second member connected to said buoyancy member by said 2s connecting element; wherein, movement of the first member causes pumping of said second fluid relative to said chamber.

(b) locating the device in a first fluid; (c) supplying the water pumped out of the device in a) to a desalination plant.

Furthermore the invention provides a device which can be used for the desalination of water.

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Brief Description of the Drawings

The invention will now be described by way of example only and with reference to the accompanying drawings in which; Figure 1 is a schematic representation of a device according to the invention.

Figure 2 is a schematic representation of the device of Fig. 1 in operation showing movement of the first member relative to an increase in the level of a lo first fluid.

Figure 3 is a schematic representation of the device of Fig. 1 in operation showing movement of the first member relative to a decrease in the level of a first fluid.

Figure 4 is a schematic representation of a second embodiment of the device according to the invention.

Figure Sa is a schematic representation of a third embodiment of the device according to the invention; Figure 5b is a plan view of the device illustrated in Figure 5a.

Figure 6a is a cross section through the device shown in Figure 5alb.

2s Figure 6b illustrates the general arrangement of the device according to the invention.

Figure 7 illustrates a plurality of the devices according to the invention linked a water turbine generator unit. 3s

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Detailed Description

Figure 1 shows a schematic representation of the device (1). A first member (2) is neutrally buoyant and is submerged within a first fluid (3). This first member is connected by a connecting element (4) to a second member (5). This second member is a diaphragm which is fixedly attached (6) to an interior wall of a chamber (7). This diaphragm divides the chamber into a lower sub-chamber (7a) and an upper sub- chamber (7b).

0 The diaphragm is also secured to the connecting element by being sandwiched between two closely disposed plates (8) at the end of the lower end of the connecting element. The connecting element forms a telescopic pair of shafts with an anchoring shaft (9), with the connecting element sliding over the anchoring shaft in response to vertical movements of the first member.

A two-way valve (lea) is positioned in a wall of the lower chamber and another two- way valve (lOb) in a wall of the upper sub-chamber. These valves control the inflow and outflow of the second fluid within the chamber. The flow of fluid into the lower sub-chamber is via pipeline (11 a), whilst the flow of fluid into the upper sub-chamber is via pipeline (1 lb). The pipe- lines also supply the pumped fluid under pressure to the required point of use, for example an electricity generator or desalination plant.

The device also comprise a support structure (12) which comprises a plurality of vertical supports (13) which guide the vertical movement of the first member.

Figure 2 is a schematic of the device (1) in operation as the level of the first fluid (3) rises. The first member (2), which is submerged in this first fluid, rises as the level of the first fluid rises. The force generated by this movement is transmitted through the connecting element (4) to pull the diaphragm (5) upwards inside the chamber (7). This results in the volume of the lower sub-chamber (7a) increasing whilst the volume of the upper sub-chamber (7b) decreases.

On this upward stoke the movement of the second fluid in relation to the chamber is two-fold. In the lower sub-chamber (7a) the fluid enters by suction pressure along e. Be: B:e ce:: 4.

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pipe-line (lla), through the valve (lea) to fill the increased volume of the sub- chamber. In comparison, in the upper sub-chamber the vertical movement of the diaphragm reduces the volume of the sub-chamber which causes the second fluid to be pushed or pumped through the valve (lob), and it is then transported along pipe- line (1 lb). For clarity the fluid in the upper sub-chamber is not shown in this figure.

Figure 3 is a schematic of the device (1) in operation as the level of the first fluid (3) falls. The first member (2), which is submerged in this first fluid, falls as the level of the first fluid falls. The position of the diaphragm (5) lowers relative to the chamber lo (7). This results in the volume of the lower sub-chamber (7a) decreasing whilst the volume of the upper sub-chamber (7b) increases.

On this downward stoke the movement of the second fluid in relation to the chamber is two-fold. In the lower sub-chamber (7a) the down-ward vertical movement of the diaphragm reduces the volume of the sub-chamber which pushes or pumps the second fluid out through the valve (1 Oa) which is then transported along a pipe-line (1 la). In comparison in the upper sub-chamber the fluid enters by suction pressure along a pipe-line (llb), through the valve (lOb) to fill the increased volume of the sub- chamber. For clarity the fluid in the upper sub-chamber is not shown on this figure.

It will be appreciated that the buoyant member 2 may be connected to the diaphragm by any suitable means.

For example a lever arm 100 may be employed to connect the connecting element 4 to 2s the diaphragm 5, as illustrated in Fig. 4. In this case, the lever arm 100 is fixedly attached to the sea bed at one end and is connected to the diaphragm 5 at the other end. In this manner the lever arm 100 forms a lever of the third kind to produce a relatively large movement of the diaphragm 5 for a relatively small movement of the surface of the sea water.

Figures 5-6 are further illustration of the device of the invention.

Figure 7 illustrates a plurality of the devices according to the invention linked a water turbine generator unit.

8 8 8 8 À 8 8 1 8 8 8 8 8 8 8 8 8 8 8 d 8 8 8 e 8 À À The invention is not limited to the embodiments hereinbefore described, with reference to the accompanying drawings, which may be varied in construction and detail.

Claims

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À C C CC C C* C C * * C C C * À * C * C C * C * * C C C C Claims 1. A device comprising; s a first member configured to be buoyant in a first fluid; a connecting element; a chamber suitable for containing a second fluid; a second member connected to said buoyancy member by said connecting element; lo wherein, movement of the first member causes pumping of a second fluid relative to said chamber.
2. A device according to claim 1, wherein said device comprises a support structure.
3. A device according to claim 2, wherein said support structure is suitable for resting on a sea floor.
4. A device according to claim 2, wherein said support structure is suitable for securment to a sea floor.
5. A device according to any of claims 2 to 4, wherein said support structure comprises a plurality of vertical supports to guide movement of said first member.
6. A device according to any of claims 2 to 5, wherein said support structure 2s comprises a telescopic shaft located relative to said connecting element to guide movement of said connecting element.
7. A device according to any of claims 2 to 6, wherein said telescopic shaft is suitable for securment to a sea floor.
8. A device according to claim 1, wherein said second member is located in said chamber. t t À À
9. A device according to claim 8, wherein said second member is moveable relative to said chamber to cause pumping of fluid.
10. A device according to claim 8 or 9, wherein said second member is fixedly s attached to the inner surface of said chamber, thereby subdividing said chamber into at least two subchambers.
11. A device according to any of claims 8-10, wherein said second member comprises a diaphragm.
12.A device according to claim 11, wherein said diaphragm is secured to said connecting element.
13. A device according to claim 12, wherein said diaphragm is sealingly secured to said connecting element.
14. A device according to claims 12 or 13, wherein said diaphragm is sandwiched between a pair of closely disposed plates provided on said connecting means.
15. A device according to any of claims 1 or claims 10 or 1 1 wherein said connecting means is a shaft.
16. A device according to claim 1 or 9, wherein said subchambers are provided with at least one valve for the control of fluid flow relative to said chamber.
17. A device according to claim 16, wherein said valve is a two-way valve.
18. A device according to claim 1, wherein said first member is moveable in response to changes in the level of a first fluid.
19. A device according to claim 1, wherein said first fluid andlor said second fluid is a liquid.
20. A device according to claim 19, wherein said liquid is water.

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21. A device according to Claim 20, wherein said water is sea water.
22. A device according to claim 18, wherein said movements in said first fluid level are tidal oscillations.
23. A device according to claims 1, wherein said first member is suitable for floating on or at the surface of a liquid.

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24. A device according to claims 23, wherein said first member is a pontoon.
25. A device according to claim 1, where said first member is neutrally buoyant.
26. A device according to claims 1, wherein said first member is suitable for submersion within a liquid.
27. A method for generating electricity comprising the steps of; (a) providing a device comprising; a first member configured to be buoyant in a first fluid; a connecting element; a chamber suitable for containing a second fluid; a second member connected to said buoyancy member by said connecting element; wherein, movement of the first member causes pumping of said second fluid relative to said chamber.

(d) locating the device in a first fluid; (e) supplying the water pumped out of the device in a) to a generator.
28. A method for desalinating water comprising the steps of; (a) providing a device comprising; a first member configured to be buoyant in a first fluid; a connecting element; a chamber suitable for containing a second fluid; # e::; .e::: À À 1 À a second member connected to said buoyancy member by said connecting element; wherein, movement of the first member causes pumping of said second fluid relative to said chamber.

s (d) locating the device in a first fluid; (e) supplying the water pumped out of the device in a) to a desalination plant.
29. A device substantially as hereinbefore described with reference to the accompanying drawings.
30. A method substantially as hereinbefore described with reference to the accompanying drawings.