GB2527311A

GB2527311A - Water turbine

Info

Publication number: GB2527311A
Application number: GB1410751.0A
Authority: GB
Inventors: Barry Bristow
Original assignee: BLUE TIDAL ENERGY Ltd
Current assignee: BLUE TIDAL ENERGY Ltd
Priority date: 2014-06-17
Filing date: 2014-06-17
Publication date: 2015-12-23
Also published as: GB201410751D0

Abstract

A water turbine assembly 10 for installation on a sea or river bed 20 comprises two vertical support columns 30, 30' for engaging the sea or river bed, with at least two tension members e.g. cables 320 and at least two compression members e.g. struts 330 configured to be held in tension / compression between the columns and the bed. A turbine 40.1 is supported by the vertical support columns 30, 30' so as to be moveable up and down along the columns. Two or more turbines may be installed in a stack 40. A generator 80 having an input shaft connected with the output shaft of the turbine is configured to be moveable up and down relative to the columns 30,30' and independently of the turbine 40.1. There may be more than two support columns (30, 30', 30", figure 5B) arranged in a line to support turbines 40.1 in each space between successive columns.

Description

TITLE: WATER TURBINE

TECHNICAL FIELD

The present invention relates to water turbines for installation on a sea-or river bed, 1 0 in particular structural support therefor.

BACKGROUND ART

It is known, e.g. from WO2004/085845, to provide a water turbine support assembly for installation on a sea or river bed and comprising at least two vertical columns known as piles, resting or indented into the seabed and protruding above the water line at all stages of tide. Between the piles, water turbines are connected to the piles in such a way as to allow them to be raised to the surface for the purposes of maintenance or replacement.

Manufacture and installation of piles in the open sea is a well-established technology; however, difficulties can include a requirement for large diameter piles to provide for the large bending moments of the traditional unsupported piles, the cost of deep drilling and hammering the piles into the ground and the cost of large support vessels for this installation.

The figures and abstract of WO2O 12/03 0074 disclose another water turbine assembly in which four piles are mounted in a line transverse to the water flow direction, one water turbine being connected between the first and second piles and another water turbine being connected between the third and fourth piles. A flow path cut-off member' or shroud is connected between the second and third piles so as to direct water through the turbines between the firstlsecond and third/fourth piles.

DISCLOSURE OF INVENTION

According to a first aspect of the invention, there is provided a water turbine assembly for installation on a sea-or river bed, the assembly comprising: two vertical support columns for engaging the sea-or river bed; a turbine having an output shaft and configured to convert the power of flowing water into rotational power at the output shaft, the turbine being supported by the vertical support columns so as to be moveable up and down along the columns; a transducer having an input shaft connected with the output shaft of the turbine and configured to convert the rotational power of the input shaft, the transducer being configured to be moveable up and down relative to the columns and independently of the turbine.

Such an arrangement enables better utilisation of the water flow. Specifically, the arrangement allows the transducer -typically an electrical generator -to be raised up relative to the two colunms, out of the water, and the turbine to be lowered down the columns, thereby allowing a further turbine module to be attached to the columns and lowered into the water. If appropriate, this can be repeated until the entire water depth (water column') is occupied by a vertical stack of turbines, following which the generator can be lowered down relative to the columns and into connection with all the turbines (the generator size may have to be adjusted depending on the number of turbines). Such a stack of turbines can he assembled using relatively small installation vessels, thereby reducing installation costs.

The transducer may be supported by said vertical support columns so as to be moveable up and down the columns.

The input shaft of the transducer may be moveable coaxially with the output shaft of the turbine.

The transducer and turbine may be supported by common vertical support columns.

The transducer and turbine may each be configured for sliding engagement with two common vertical support columns that are transversely spaced. With each module having one attachment on each side and being fixed together the resulting combination will be a turbine able to generate energy from the tidal stream.

The turbine may be configured to have variable buoyancy. The turbine may comprise at least one variable buoyancy ballast tank. The transducer may be not be buoyant.

The transducer may be supportable by the turbine, The assembly may comprise a first turbine and a second turbine, each supported by the vertical support columns so as to be moveable up and down along the columns. Adding turbine modules in this way allows more of the water column to be exploited for its stream energy.

The first and second turbines may have respective first and second output shafts, the first and second output shafts being coaxial.

The first and second turbine may each be configured for sliding engagement with the two common vertical support columns that are transversely spaced.

The first turbine may be configured to have variable buoyancy. The second turbine may not be buoyant and will not require its own ballast tanks. Instead, the second turbine may be supported by the first turbine. The transducer may be supported by the second turbine.

Further turbine(s) can be stacked on top of the second turbine by repeating the process. When the desired number of turbine modules have been stacked, the transducer module can be place on the top of the stack and mechanically connected thereto such that it is driven by all the turbines in the stack.

The mechanism for sliding engagement between a turbine or transducer and a vertical support column may be adjustable, e.g. to compensate for inaccuracies in the positioning of the column, particularly in open water conditions.

The mechanism of the first column may be adjustable and the mechanism of the second column non-adjustable. This ensures that the two tracks are parallel to ensure the cluster can be easily moved up and down in the water column.

According to a second aspect of the invention, there is provided a method of deploying on a sea-or river bed a turbine assembly comprising first and second independently transportable elements, the method comprising the steps of: floating the first element into position on the surface of the sea or river; thereafter mounting the second element on top of the first element; thereafter decreasing the buoyancy of the first element, thereby lowering the turbine assembly to the sea-or river bed.

The second element may be floated into position above the first clement. Prior to mounting the second element on top of the first element, the buoyancy of the first element may be decreased such that it sinks to just below the surface of the sea or river.

The second element may be provided with detachable buoyancy members (transporter modules'). The members may be detached from the second element prior to decreasing the buoyancy of the first element so as to lower the turbine assembly to the sea-or river bed.

Prior to lowering the turbine assembly to the sea-or river-bed, the buoyancy of the first element may be varied such that the second element resides just below the surface of the water in order that a third element may thereafter be floated into position above the first element and then mounted on the second element. The third element may be provided with detachable buoyancy members (transporter modules').

The first element may be a turbine. The turbine may have variable buoyancy tanks.

The second and third elements may be a further turbine and/or a transducer, in particular an electrical generator.

It is envisaged that no repairs of the turbines will take place whilst in position in the water and only light repairs will be undertaken with the gcnerator when it is raised to the surface. Rather, it is expected that faulting modules will be replaced by serviceable 1 5 modules, the procedure of replacing modules being a reverse of the build of the cluster, To this end, the buoyancy of the first element may be increased so as to raise the assembly as a whole to the surface of the sea or river, According to a third aspect of the present invention there is provided a water turbine support assembly for installation on a sea-or river bed, the assembly including: at least two columns configured to support a water turbine therebetween and to engage the bed; wherein, to support the columns in a substantially vertical orientation, the assembly comprises: at least two tension members configured to be held in tension between the columns and the bed, and at least two compression members configured to be held in compression between the columns and the bed.

Using multiple support lines in tension and props in compression to maintain the columns in a vertical position improves the safety of the structure by providing redundancy.

Moreover, multiple support members allow the size of the columns to be much smaller due to the division of the loads between several supporting lines and props. The resulting smaller columns will require smaller support vessels for installation.

The tension and compression members may further be configured to maintain the position of the ends of the vertical columns on the bed. This may be appropriate where it is difficult to penetrate the sea-or river bed.

The tension and/or compression members may extend in a plane containing the at least two columns. The tension and/or compression members may extend substantially perpendicular to a plane containing the at least two columns. The tension/compression members may extend to either side of a plane containing the at least two columns.

According to a fourth aspect of the invention, there is provided a water turbine assembly for installation on a sea-or river bed, the assembly comprising n vertical support columns arranged in a line and defining n-i spaces between successive columns in the line, n being greater than or equal to three; wherein a water turbine is supported in each space between successive columns in the line.

Such an assembly enables the building of an array of turbines to increase the maximum energy output. For each subsequent cluster there will only be a requirement for one additional pile. This process can be extended to produce an array of any size to suit the conditions of the seabed and availability of a tidal stream.

Such an array will also have a beneficial barrage' effect on the tidal stream: the stream with any tidal device in the water will tend to flow around the device, taking the easier route; however if the distance to flow around the device is too far the stream will be forced to flow through the turbine, having a beneficial effect on the arrays' efficiency.

It should be understood that each aspect of the invention set out above can be particularlised using features of the other aspects of the invention set out above.

BRIEF DESCRIPTION OF DRAWiNGS

An embodiment of the invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a front elevation of a water turbine assembly in accordance with the present invention; Figure 2A is a perspective view of the bottom-most turbine module of figure 1; Figure 2B is a perspective view of the generator module of figure 1; Figures 2C and 2D are plan and end views of a transporter module; Figure 2E is a detail view of a generator and turbine module; Figure 3 is a plan view of the turbine module 40.n of figure 2 when in situ; Figures 4A and B are detail sectional and side views of the sliding mechanism shown in figure 3; Figure 5A is a perspective view of a water turbine support assembly according to the present invention; Figure 5B is a front elevation of an array of turbines; Figure 5C is a perspective view showing detail of an intermediate column 30".

DESCRIPTION OF EMBODIMENTS

Referring to figure 1, a water turbine assembly 10 for installation on a sea-or river bed 20 comprises two vertical support columns 30,30' that engage the sea-or river bed and that are transversely spaced relative to the water flow direction D, which is perpendicular to the page as shown in figure I. A stack 40 of n turbine modules 40.1 to 40.n (modules 40.2 to 40.(n-l) being indicated by chain dotted lines) having a common axis is supported between the columns 30,30' so as to substantially completely fill the water column 70 betwccn the bed 20 and water surface 60. Each turbine module is connected on either side to the columns 30,30' by respective mechanisms 50, described in more detail below, that allow the turbine module to be slid up and down along the columns. As discussed in more detail below, each turbine module 40.1 to 40.n is configured to convert the power of the flowing water into rotational power at a respective output shaft, the output shafts of successive modules being connected together via quick release flexible couplings (indicated at 101 in figure 2E) that allow significant movement of the modules without any harmful effect on performance. Such an arrangement allows ready implementation of an angular offset between the blades of adjacent turbine modules -as known e.g. from NZ584940A -so as to improve the smootlmess of the driving torque on the generator.

A transducer module 80, in the example shown having generator 80' for converting rotational power into electrical energy, is lowered down on top of the uppermost turbine module 40.1, coaxially with the output shaft of the turbine, such that the input shaft of the generator is connected to the output shaft of the turbine 40.1 and driven by all the turbines in the stack.

As shown, the transducer module is located just under or above the water surface 60, a single moving electrical cable (not shown) transmitting the generated electricity to electrical conditioning equipment housed at the top of the columns, from where electricity is transmitted to the grid by means of cables (not shown) attached to the top of the piles 30,30'.

In another embodiment, not shown, the generator module is also connected on either side to the columns by respective mechanisms that allow the generator module to be slid up and down along the columns.

Figure 2A is a perspective view of the turbine module 40.n at the bottom of the stack. As shown, the module comprises a rectangular frame 150 accommodating a turbine having elongate blades 120 that extend parallel to, and are attached to by means of radial arms 130, a output shaft 100 rotatable about a vertical axis. However, the frame could also be square to accommodate a circular horizontal axis turbine. Module 40.n has ballast tanks 140, 140', the buoyancy of which can be adjusted in a manner known per se to support the weight of the module 40.n, the generator 80 and any intervening turbine modules 40.1 to 40.(n-1) at the required depth. The frame has an extension 160 at its top side to facilitate the positioning thereon of another turbine module or the generator module.

It follows that the supported modules 40.1 to 40.(n-1) and the generator module 80 need not have their own ballast tanks although, as shown in figure 2B, it may nevertheless be prudent for the generator module 80 to have its own buoyancy tanks 170,170' . Rather, once the variable buoyancy turbine module 40.n has been floated into position on the surface of the water and its buoyancy decreased such that it sinks to just below the surface of the water, a supported turbine module 40,(n-l) can be independently floated into position over -and attached to -module 40.n by means of a transporter module that can subsequently be removed.

Referring to figures 2C and 2D, the transporter module 610 comprises a U-shaped platform 630 supported by buoyancy tanks 600, the space 620 between the buoyancy tanks 600 being sufficient to enable the transporter module to float into position eithcr side of the connecting support structure 160 of a turbine module (as shown in figures 2A and 2E) that is already in position at the top of the stack.

Moreover, the diameter of the buoyancy tanks 600 is less than the height of that support structure 160. Accordingly, once the turbine/generator module being transported is 1 0 in position, the transporter module can bc sunk lower in the water, thereby allowing the bottom of that turbine/generator module to engage the top of the support structure 160 on module that is already in position.

Figure 2E is a detail view of the generator module 80 attached to a turbine module 40.1 at attachment points 161 on the upper surface of frame extension 160. In the interests of clarity, blades are indicated only by their centre lines 120 at the ends of radial arms 130.

and the variable pitch mechanism, which may be of the kind known from UK patent application no. 1321886.2, incorporated herein by reference, is only indicated generally at 121.

This assembly process can then be repeated, the buoyancy of the bottom-most turbine module being adjusted to allow a thrther turbine module 40.(n-2), 40.(n-3), etc. and finally a generator module 80 to be floated on to the top of the stack.

Retrieval of the complete turbine stack can be achieved by reversing the process, increasing the buoyancy of the turbine module 40.n so as to raise it and the supported turbine(s) and generator to the surface for the purpose of maintenance or replacement of any of the modules.

Figure 3 is a plan view of the turbine module 40.n of figure 2 when supported by vertical columns 30,30' by sliding mechanisms 50. Figures 4A and B show detail sectional and side views of the mechanism, which comprises a rail 200 attached to the inwardly-facing surface of the column 30 arid slidingly supporting a runner 210 attachcd to the turbine module frame 150 by means of a shackle 220. A minimum of one rail-engaging runner is provided on each side of the turbine module.

Consistent with the operating environment, the mechanism employs broad manufacturing tolerances (of the kind found typically found in agriculturai rather than aircraft engineering). Moreover, to allow for any inaccuracies in the positioning of the column, particularly in open water conditions, the rail on at least one of the columns may be adjustable so to ensure that the rails on the two columns are substantially parallel.

Figure 5 is a perspective view of the two columns 30,30' that support the turbine modules in the space 360 therebetween (the modules being omitted in the interests of clarity). As shown, the lower end of each column engages a shallow notch 300 in the seabed 20 to secure the base of each column/pile in a lateral direction, while the upper ends of the columns are connected by at least one cross-member 310. It will be necessary in this embodiment to make one of the cross members connecting the top of the piles to be removable to allow the modules to be positioned in place between the piles.

The columns are supported in a substantially vertical orientation by at least two lines 320 in tension between the columns 30,30' and the bed 20 and props 330 in both tension and compression between the columns and the bed, anchoring of the lines and props (as indicated at 340) using industry standard techniques.

As shown in figure 5, lines 320 and props 330 extend in a plane containing the at least two columns, thereby supporting the columns in a direction transverse to the directions D,D' of tidal water flow. Lines 320' and props 330" extend substantially perpendicular to, and to one side of; the plane containing the at least two columns so as to support the columns against forces acting in the direction of tidal flow D, while lines 320" and props 330' resist forces acting in other direction of tidal flow, D'.

The number of lines and props shown allows extensive redundancy It will bc appreciated that the magnitude of the tensionlcompression in individual members 320,330 will depend inter alia on the direction of water flow as indicated by arrows D and D'.

As indicated by dashcd line 370, one or more additional column(s) can be added so as to define additional spaces 360' to accommodate additional turbine stacks 40 (n columns defining n-i spaces therebetween, multiple spaces requiring n to be greater than or equal to three). As noted above and illustrated in figure SB, such an assembly enables the building of an array of turbines to increase the maximum energy output and which may also have a beneficiaL barrage' effect on the tidal stream. Figure SC shows detail of an intermediate column 30" having a rail 200.

It should be understood that this invention has been descnbed by way of examples only and that a wide variety of modifications can be made without departing from the scope of the invention.

Claims

CLAIMS1. A water turbine assembly for installation on a sea-or river bed, the assembly comprising: two vertical support columns for engaging the sea-or river bed; a turbine having an output shaft and configured to convert the power of flowing water into rotational power at the output shaft, the turbine being supported by the vertical support columns so as to be moveable up and down along the columns; a transducer having an input shaft connected with the output shaft of the turbine and configured to convert the rotational power of the input shaft, the transducer being ___ configured to be moveable up and down relative to the columns and independently of the o turbine.
2. Water turbine assembly according to claim 1, wherein the transducer is supported by said vertical support columns so as to be moveable up and down the columns.
3. Water turbine assembly according to claim I or claim 2, wherein the input shaft of the transducer is moveable coaxially with the output shaft of the turbine.
4. Water turbine assembly according to any preceding claim, wherein the transducer and turbine are each configured for sliding engagement with said vertical support columns.
5. Water turbine assembly according to any preceding claim, wherein the turbine has variable buoyancy.
6. Water turbine assembly according to claim 5, wherein the turbine comprises at least one variable buoyancy ballast tank.
7. Water turbine assembly according to claim 5 or claim 6, wherein the transducer is not buoyant and, in its operative position, is supported by the turbine.
8. Water turbine assembly according to any preceding claim and comprising a first turbine and a second turbine, each supported by the vertical support columns so as to be moveable up and down along the columns.
9. Water turbine assembly according to claim 8, wherein the first and second turbines have respective first and second output shafts, the first and second output shafts being (\j coaxial.
10. Water turbine assembly according to claim 8 or claim 9, wherein the first and second turbine are each configured for sliding engagement with the two vertical support columns.
II. Water turbine assembly according to any one of claims 8 to 10, wherein the first turbine is configured to have variable buoyancy.
12. Water turbine assembly according to claim any one of claims 8 to 11, wherein the second turbine is not buoyant and, when in its operative position, is supported by the first turbine.
13. Water turbine assembly according to claim 12, wherein the transducer is not buoyant and, in its operative position, is supported by the second turbine.
14. Water turbine assembly according to claim 4, wherein the mechanism for sliding engagement between a turbine or transducer and a vertical support column is adjustable.
15. Water turbine assembly according to claim 14, wherein the mechanism for sliding engagement with a first column is adjustable and the mechanism for sliding engagement with a second column is non-adjustable. (0
16. Method of deploying on a sea-or river bed a turbine assembly comprising first and second independently transportable elements, the method comprising the steps of: floating the first element into position on the surface of the sea or river; thereafter mounting the second element on top of the first element; thereafter decreasing the buoyancy of the first element, thereby lowering the turbine assembly to the sea-or river bed.
17. Method according to claim 16, further comprising the step of floating the second element into position above the first element.
18. Method according to claim 17 and further comprising the step, prior to mounting the second element on top of the first element, of decreasing the buoyancy of the first element such that it sinks to just below the surface of the sea or river.
19. Method according to claim 17 and comprising the step of providing at least one detachable buoyancy member to support the second element.S
20. Method according to claims 18 and 19 and comprising the step of detaching the at least one buoyancy member prior to decreasing the buoyancy of the first element so as to lower the turbine assembly to the sea-or river bed.
21. Method according to any one of claims 16 to 20 and frirther comprising the step, prior to lowering the turbine assembly to the sea-or river-bed, of varying the buoyancy of the first element such that the second element resides just below the surface of the water, thereafter floating a third element into position above the first element and thereafter mounting the third element on top of the second element.
22. Method according to any one of claims 16 to 21, wherein the first element and second elements are turbines and the third element is a transducer, in particular an electrical generator.
23. Method according to any one of claims 16 to 22 and comprising the step of increasing the buoyancy of the first element so as to raise the assembly as a whole to the surface of the sea or river.
24. A water turbine support assembly for installation on a sea-or river bed, the assembly including: at least two columns configured to support a water turbine therebetween and to engage the bed, wherein, to support the columns in a substantially vertical orientation, the assembly comprises: at least two tension members configured to be held in tension between the columns and the bed, and at least two compression members configured to be held in compression between the columns and the bed.
25. Water turbine support assembly according to claim 24, wherein the tension and compression members are configured to maintain the position of the ends of the vertical columns on the bed.
26. Water turbine support assembly according to claim 24 or claim 25, wherein the tension and/or compression members extend in a plane containing the at least two columns.
27. Water turbine support assembly according to claim 24 or claim 25, wherein the tension and/or compression members extend substantially perpendicular to a plane containing the at least two columns.
28. Water turbine assembly according to claim 24 or claim 25, wherein the tension and/or compression members extend to either side of a plane containing the at least two columns.
29. A water turbine assembly for installation on a sea-or river bed, the assembly comprising n vertical support columns arranged in a line and defining n-I spaces between successive columns in the line, n being greater than or equal to three; wherein a water turbine is supported in each space between successive columns in the line.CD (4