GB2281758A

GB2281758A - The production of useful power by use of a head of water

Info

Publication number: GB2281758A
Application number: GB9319028A
Authority: GB
Inventors: Jonathan Conrad Pidgeon
Original assignee: Individual
Current assignee: Individual
Priority date: 1993-09-14
Filing date: 1993-09-14
Publication date: 1995-03-15
Anticipated expiration: 2013-09-14
Also published as: GB2281758B; GB9319028D0

Abstract

Apparatus 1 for using a head 2 of water existing between relatively high and relatively low levels 3, 4 separated by a retaining wall 5 comprises an elongate, upwardly extending air and water mixing duct 6 with an open, lower, bell-mouthed end 7 immersed in the low level water 4. Syphon-inducing means 8 are provided for transporting high level water 3 to the upper end 9 of the duct 6 so that the water flows downwardly, intraining air introduced by means of a nozzle 10. Air collected in a separating chamber 15 drives an air turbine 16. Alternative air collection arrangements, syphon configurations and valving arrangements are disclosed (figures 2 and 4) and a fish rest pool (70) (figure 3) may be provided. <IMAGE>

Description

IMPROVEMENTS IN OR RELATING TO THE PRODUCTION OF USEFUL POWER BY USE OF A HEAD OF WATER This invention relates to the production of useful power by use of a head of water.

The invention has particular application to the use of relatively low heads, (say up to 10.0 metres) of water separated by a retaining wall, and can be used to produce useful power in the form of pressurised air.

According to one aspect of the invention, apparatus for using a head of water existing between relatively high and low levels of water, separated by a retaining wall, comprises: an upwardly extending air and water mixing duct disposed on the low level side of the wall, the duct having an open, lower end immersed in the low level water, means for transporting high level water to the upper end of the duct so that it flows downwardly through the duct towards the low level water, means for introducing air into the upper end of the duct so that it becomes entrained in the downward flow of water through the duct, means for collecting the air after passage through the duct, and means for extracting energy from the collected air, and/or air introduced into the upper end of the duct.

According to another aspect of the invention, a method of using a head of water existing between relatively high and low levels of water, separated by a retaining wall, comprises the steps of: disposing an elongate, open-ended air and water mixing duct on the low level side of the wall, so that it extends upwardly, and so that the open, lower end of the duct is immersed in the low level water, transporting high level water to the upper end of the duct so that it flows downwardly through the duct towards and into the low level water, introducing air into the upper end of the duct so that it becomes entrained in the downward flow of water through the duct, collecting the air after passage through the duct, and extracting energy from the collected air, and/or air introduced into the upper end of the duct.

As used herein, the term 'wall' includes a dam, weir, bank, tidal barrier or other structure which separates two levels of water.

The means for transporting high level water to the upper end of the duct preferably comprises syphon-inducing means.

An embodiment of the invention will now be described by way of example only, with reference to the accompanying drawings, wherein: Figure 1 is a side view, chiefly in section, of apparatus according to the invention, Figures 2, 3 and 5 are similar views which illustrate modifications, Figure 5 is a cross-sectional view, taken on the lines V-V of Figure 3, and Figure 6 illustrates an optional arrangement.

In the figures, like reference numerals refer to like components and features.

With reference to Figure 1, apparatus 1 is shown for using a head 2 of water existing between relatively high and relatively low levels 3, 4 separated by a retaining wall 5.

The apparatus 1 comprises an elongate, upwardly extending air and water mixing duct 6 of divergent form disposed on the low level side of the wall 5. The duct 6 has an open, lower, bell-mouthed end 7 immersed in the low level water 4.

The apparatus 1 further comprises syphon-inducing means 8 for transporting high level water 3 to the upper end 9 of the duct so that the water flows downwardly, under gravity, to the low level water 4. Air is introduced into the upper end 9 of the duct 6 by means of a nozzle 10, so that the air becomes entrained in the downward flow of water through the duct 6. A separating chamber 15 provides means for collecting the air after passage through the duct 6 and means comprising an air turbine 16 provides means for extracting energy from the collected air.

The nozzle 9 is disposed substantially centrally within the duct upper or inlet end 9. The nozzle air supply line 17 is sealed to the duct 6 by a gland 18. A flow control valve 19 is disposed in the line 17, which is open to atmosphere.

A vacuum break and syphon line 25 provided with a control valve 26 is connected to the upper end 9 of the duct 6.

The syphon-inducing means 8 comprises a water transport duct 27 having a lower end 28 immersed in the high level water 3 and an upper end 29 connected to the upper end 9 of the duct 6. The lower end 28 of the duct 27 is of outwardly flared form when viewed in plan.

A deflector 35 is disposed beneath the lower end 7 of the duct 6, and is spaced therefrom. The deflector 35 serves to change the direction of the downwardly flowing air and mixture, from a substantially axial flow to a radially-extending one.

The separating chamber 15 is of annular form and extends around the lower end of the duct 6. The chamber 15 is open-bottomed so as to define, with the deflector 35, a radial path 36 for the escape of the water/air mixture.

A pressurised air outlet line 37 with a flow control valve 38 extends between the interior of the chamber 15 and the inlet 39 of the turbine 16.

The turbine 16 drives a generator 45 whereby useful electrical power is generated, which can be fed to the National Grid. The turbine 16 exhausts to atmosphere by way of an outlet 46.

A vacuum break-line 51 with a control valve 52 is connected to the line 25 at a point between the vacuum pump 50 and valve 26.

In operation, with the control valves 19 and 38 closed, air is removed from within the apparatus 1 by way of the valve 26, line 25 and the vacuum pump 50.

As air pressure is reduced within the apparatus 1, water is induced to flow upwardly through the duct 27, as well as upwardly through the duct 6.

The water levels in the ducts 6, 27 continue to rise until air trapped in the upper end 9 of the duct 6 is entrained by water syphoned up the duct 27 and into the duct 6, the mixture of air and water flowing downwardly through the duct 6.

When the duct 27 is full of water, the flow of water past the nozzle 10 reduces the local pressure, creating a venturi effect. Ambient air is then admitted to the nozzle 10 by opening the control valve 19. This air is induced into the nozzle 10 because of the reduction in local pressure at the nozzle outlet. The valve 26 can now be closed and the associated vacuum pump 50 shut down.

The incoming air forms bubbles which are drawn downwards with the flow of water through the duct 6 out of the bell-mouthed lower end 7 and into the separating chamber 15. Water then flows radially out of the chamber 15, by way of the annular path 36, and air separates from the air/water mixture to collect in the free air space 58 of the chamber 15, which space is below the surface of the low level water 4.

The air/water mixture leaves the lower end 7 in a divergent manner and in a substantially horizontal plane. The air bubbles in the exiting mixture have a substantially vertical component of velocity so that they pass upwardly along a curved path, to leave the water and enter the air space 58 enclosed by the chamber 15, as indicated by arrows 59.

As air collected in the air space 58 of the chamber 15 builds up in pressure, the control valve 38 is opened, whereby the pressurised air is used to drive the turbine 16.

More than one turbine 16 may be provided.

Control of the apparatus 1 is by regulation of the air inlet control valve 19. To shut down the apparatus 1, the valve 19 is closed and atmospheric air admitted to the system by way of the line 51, valve 52, line 25 and valve 26. This action stops water being drawn up the duct 27 by breaking the syphon action.

Flaring out the bottom end 7 of the duct 6 tends to reduce the velocity of the air/water mixture at exit, and hence its kinetic energy.

The deflector 35 changes the direction of the existing air/water mixture from the substantially vertical to the substantially horizontal. The shape of the deflector further reduces the velocity of the exiting air/water mixture by increasing the volume available to the radially flowing mixture. The deflector 35 also, by changing the direction of the exiting air/water mixture, allows easier separation of air bubbles from the mixture.

With reference to Figure 6, a further air turbine, namely secondary air turbine 54, may be provided if desired. The secondary air turbine 54 is used to extract energy from incoming air.

The turbine 54 is arranged so that it is connected into the air supply line 17 with its inlet open to atmosphere and so that its outlet discharges air to the nozzle 10.

The turbine 54 drives a generator 45 whereby useful electric power is produced, which may be coupled with that produced by generator 45.

(Figure 1.) Figure 2 illustrates an alternative arrangement for air/water separation.

The apparatus la has a duct 6 provided with a downwardly and laterally extending extension 60 disposed beneath the chamber 15.

The extension 60 replaces the bell-mouthed bottom end 7 and deflector 35 of Figure 1, the laterally-extending portion of the extension 60 serving as a deflector.

In the modification illustrated by Figures 3 and 5, apparatus lb is provided with a fish rest pool 70, comprising a chamber 71 incorporated in a syphon duct 27b. As shown, fish can pass upstream from lower level 4 to high level 3, by way of the duct 6, rest pool 70 and duct 27b.

Passage of the fish, which may also take place in the reverse direction, is without injury.

The rest pool 70 can be drained by use of a drain line 72 and drain valve 73. Alternatively, the pool 70 can be formed so that it selfdrains down duct 27b.

Apparatus according to the invention will allow, within reason, the passage of debris between the water levels, without damage.

Several apparatus may be installed on the same site. They may share components and have, for example, a common air inlet and a common pressurised air outlet leading to one or more air turbines.

Individual apparatus can be brought into and out of operation, according to requirements and water availability.

Figure 4 illustrates apparatus 80, which may be duplicated. The apparatus 80 comprises a pair of apparatus 1 interconnected by a duct 81, one apparatus on one side of the wall 5, and the other apparatus on the opposite side of the wall.

The apparatus 1 on the high water level side serves as a syphon in order to supply water to the apparatus 1 on the low water level side, the syphoned water being induced to flow through the interconnecting duct 81.

In this arrangement the nozzle 10 on the high water level side of apparatus 1 is not used, and the pressurised air outlet valve 38 of said apparatus is kept closed.

Where possible, any of the features disclosed herein may be added to, or substituted for, other of said features.

Claims

1. Apparatus for using a head of water existing between relatively high and low levels of water, separated by a retaining wall, comprising: an upwardly extending air and water mixing duct disposed on the low level side of the wall, the duct having an open, lower end immersed in the low level water, means for transporting high level water to the upper end of the duct so that it flows downwardly through the duct towards the low level water, means for introducing air into the upper end of the duct so that it becomes entrained in the downward flow of water through the duct, means for collecting the air after passage through the duct, and means for extracting energy from the collected air, and/or air introduced into the upper end of the duct.

2. Apparatus as claimed in claim 1, wherein the means for transporting high level water to the upper end of the duct comprise syphon-inducing means.

3. Apparatus as claimed in claim 2, wherein the syphon-inducing means comprise a water transport duct having a lower end immersed in the high level water and an upper end connected to the upper end of the air and water mixing duct.

4. Apparatus as claimed in claim 3, wherein the lower end of the water transport duct is outwardly flared when viewed in plan.

5. Apparatus as claimed in any one of claims 1 to 4, wherein the means for extracting energy from the collected air, and/or air introduced into the upper end of the duct, comprise at least one air turbine.

6. Apparatus as claimed in claim 5, wherein the air turbine is used to drive an electrical power generator.

7. Apparatus as claimed in any one of claims 1 to 6, wherein the means for collecting air after passage through the duct comprise an air/water separating chamber.

8. Apparatus as claimed in claim 7, wherein the separating chamber is annular and surrounds the lower end of the air and water mixing duct.

9. Apparatus as claimed in claim 8, wherein the chamber is openbottomed.

10. Apparatus as claimed in claim 9, wherein a deflector is disposed beneath the lower end of the air and water mixing duct so as to define, with the open-bottomed separating chamber, a radial path for the escape of air/water mixture from the separating chamber.

11. Apparatus as claimed in claim 10, wherein the lower end of the air and water mixing duct is bell-mouthed.

12. Apparatus as claimed in any one of claims 1 to 11, wherein an air-introducing nozzle is disposed in the upper end of the air and water mixing duct, whereby air is entrained in the downward flow of water through the duct.

13. Apparatus as claimed in claim 12, provided with means for removing air from the upper end of the air and water mixing duct.

14. Apparatus as claimed in claim 13, wherein the air removal means comprise a vacuum pump.

15. Apparatus as claimed in any one of claims 1 to 14, provided with means for extracting energy from air introduced into the upper end of the air and water mixing duct.

16. Apparatus as claimed in claim 15, wherein the means for extracting energy from air so introduced comprise air turbine means.

17. Apparatus as claimed in claim 15 or 16, wherein the energy extracted from air so introduced is used to drive an electrical power generator.

18 Apparatus as claimed in any one of claims 1 to 9, or 12 to 15 when not dependent from claim 10 or 11, wherein the lower end of the air and water mixing duct is provided with a downwardly and laterally extending extension, so as to define a lateral path for the escape of air/water mixture from the separating chamber.

19. Apparatus as claimed in any one of claims 3 to 18, provided with a fish rest pool incorporated in the water transport duct.

20. Apparatus as claimed in claim 2, wherein the syphon-inducing means comprise a syphon-inducing duct disposed on the high level side of the retaining wall, connected by a water transport duct to the upper end of the air and water mixing duct.

21. Apparatus as claimed in claim 20, wherein the syphon-inducing duct is of divergent form, the lower end of said duct being the larger end, said larger end being bell-mouthed.

22. A method of using a head of water existing between relatively high and low levels of water, separated by a retaining wall, comprises the steps of: (a) disposing an elongate, open-ended air and water mixing duct on the low level side of the wall, so that it extends upwardly, and so that the open, lower end of the duct is immersed in the low level water, (b) transporting high level water to the upper end of the duct so that it flows downwardly through the duct towards and into the low level water, (c) introducing air into the upper end of the duct so that it becomes entrained in the downward flow of water through the duct, (d) collecting the air after passage through the duct, and (e) extracting energy from the collected air, and/or air introduced into the upper end of the duct.

23. The method claimed in claim 22, wherein step (b) is performed by use of syphon-inducing means.

24. The method claimed in claim 22, wherein the syphon-inducing means comprise a water-transport duct having a lower end immersed in the high level water and an upper end connected to the upper end of the air and water mixing duct.

25. The method claimed in any one of claims 22 to 24, wherein step te) is performed by use of at least one air turbine.

26. The method claimed in claim 25, wherein the air turbine is used to drive an electrical power generator.

27. The method claimed in any one of claims 22 to 26, wherein step (d) is performed by use of an air/water separating chamber.

28. The method claimed in any one of claims 24 to 27, wherein step (c) is performed by us of an air-introducing nozzle disposed in the upper end of the air and water mixing duct, whereby air is entrained in the downward flow of water through the duct.

29. The method claimed in claim 23, wherein step (b) is performed by use of a syphon-inducing duct disposed on the high level side of the retaining wall, connected by a water transport duct to the upper end of the air and water mixing duct.

30. The method claimed in claim 29, wherein the syphon-inducing duct is of divergent form, the lower end of said duct being the larger end, said larger end being bell-mouthed.

31. Apparatus for using a head of water existing between relatively high and low levels of water, substantially as hereinbefore described with reference to Figure 1 of the accompanying drawings.

32. Apparatus for using a head of water existing between relatively high and low levels of water, substantially as hereinbefore described with reference to Figure 2 of the accompanying drawings.

33. Apparatus for using a head of water existing between relatively high and low levels of water, substantially as hereinbefore described with reference to Figures 3 and 5 of the accompanying drawings.

34. Apparatus for using a head of water existing between relatively high and low levels of water, substantially as hereinbefore described with reference to Figure 4 of the accompanying drawings.

35. Apparatus for using a head of water existing between relatively high and low levels of water, substantially as hereinbefore described with reference to Figures 1 and 6 of the accompanying drawings.

36. A method of using a head of water existing between relatively high and low levels of water, substantially as hereinbefore described with reference to Figure 1 of the accompanying drawings.

37. A method of using a head of water existing between relatively high and low levels of water, substantially as hereinbefore described with reference to Figure 2 of the accompanying drawings.

38. A method of using a head of water existing between relatively high and low levels of water, substantially as hereinbefore described with reference to Figures 3 and 5 of the accompanying drawings.

39. A method of using a head of water existing between relatively high and low levels of water, substantially as hereinbefore described with reference to Figure 4 of the accompanying drawings.

40. A method of using a head of water existing between relatively high and low levels of water, substantially as hereinbefore described with reference to Figures 1 and 6 of the accompanying drawings.