GB2524054A

GB2524054A - Connector

Info

Publication number: GB2524054A
Application number: GB1404414.3A
Authority: GB
Inventors: William Braithwaite
Original assignee: Marine Current Turbines Ltd
Current assignee: Marine Current Turbines Ltd
Priority date: 2014-03-13
Filing date: 2014-03-13
Publication date: 2015-09-16
Also published as: GB201404414D0

Abstract

A two part ball and indentation connector and a method of installing and retrieval thereof, comprises a hollow body 26, an insert 37 and a plurality of balls 29 in a first part 26. In a second part 28, one or more indentations 33 are adapted to contact the balls of the first part. The insert 37 is adapted to move between an open position out of contact with the balls 29 and a closed position in contact with the balls. The connector is suitable for use to connect a powertrain of a sub sea turbine to a sub sea mounting.

Description

CONNECTOR

This invention relates to a connector, in particular for connection of a powertrain of a sub-sea turbine to a sub-sea mounting.

Sub-sea turbine assemblies may be tower mounted with control electronics in part of the tower which is not below the sea surface, or mounted on a structure entirely below the sea surface, In some turbine assemblies, the alignment of the assembly is fixed and the pitch of the turbine blades is altered to allow for a change in direction of tidal flow. In other turbine assemblies, the whole assembly is able to rotate about an axis of the structure on which the turbine is mounted, allowing yaw with respect to a direction of water flow during operation, whereby the turbine assembly aligns itself with the flow of water. Whether fixed alignment, or a mechanism which allows yaw, there are issues with installation and retrieval of the turbine assemblies in sub-sea installations which are not found with tower mounted assemblies, In accordance with a first aspect of the present invention a two part connector comprises a hollow body, an insert and a plurality of balls in a first part; and in a second part, one or more indentations adapted to contact the balls; wherein the insert is adapted to move between an open position out of contact with the balls and a closed position in contact with the balls, The present invention provides a simple and effective connector for a water current turbine which improves efficiency of installation and retrieval, Movement of the insert from its open position where the balls are not in the indentations to its closed position, forces the balls out to hold the two parts together.

Preferably, the balls are located between the insert and the indentations.

Although the hollow body may be located outside the insert, balls and indentations, preferably the hollow body is located between the balls and the indentations.

Preferably, the hollow body is provided with circular openings having a circumference less than the circumference of the balls.

That part of each ball which protrudes through the circular openings is received in the indentations and held in place by the insert to lock one part of the connector to the other, Preferably, a cross section of each of the first and second part is circular.

Adjacent circular openings may be offset from one another around the circumference, but preferably adjacent circular openings are located on the same circumference of the hollow body.

For installation where the direction of tidal flow is continuously varing, the indentation may comprise a continuous groove and the connector may comprise two parallel indentations.

Preferably, the first part comprises a pile.

In one embodiment, the indentations may be formed in the inner surface of the pile.

Preferably, the hollow body comprises an extension of a turbine powertrain housing.

In accordance with a second aspect of the present invention, a sub-sea turbine installation comprises a turbine powertrain, a sub-sea mounting and a connector according to the first aspect.

In accordance with a third aspect of the present invention, a method of installing a sub-sea turbine assembly comprises providing a pile with one or more indentations; providing an extension of a turbine assembly housing, the extension comprising a hollow body, an insert and a plurality of balls; lowering the sub-sea turbine assembly on a lowering device towards a sub-sea pile until the hollow body and the pile come into contact; continuing to lower the insert, such that the insert pushes the balls into contact with the indentations; and disconnecting the turbine assembly from the lowering device.

In accordance with a fourth aspect of the present invention, a method of retrieving a sub-sea turbine assembly having an extension of a turbine assembly housing comprising a hollow body, an insert and a plurality of balls from a pile with one or more indentations; the method comprising connecting the turbine assembly to a lifting device; lifling the turbine assembly until the insert is raised sufficiently to allow the balls to move out of contact with the indentations; and continuing to lift the turbine assembly off the pile.

An example of a connector according to the present invention will now be described with reference to the accompanying drawings in which: Figure 1 illustrates a tower mounted sub-sea turbine assembly; Figure 2 illustrates a pile mounted sub-sea turbine assembly incorporating a connector according to the present invention; Figure 3 is a perspective view of an example of a connector according to the present invention for use in the assembly of Fig.2; Figure 4 is a section through a connector according to the present invention; Figures 5a to 3d illustrate operation of the connector ofFigs.3 and 4 in more details; Figure 6a and 6b illustrate an alternative embodiment of the connector of the present invention; and, Figs.7a and 7b illustrate an alternative arrangement for the recesses to receive the balls.

Figure 1 illustrates an example of a three-bladed tower-mounted sub-sea turbine powertrain. The three-blades of the turbine I are mounted via a hub 2 to a -housing containing a gearbox, generator and brake. Also, within the housing, arecontrol electronics and hydraulics. In this example, one turbine is mounted at each end of a cross beam 3 which can be raised up or lowered down a tower 5, on a support 4, for example by chains and pulleys in a platform 6 at the top of the tower, or lift legs 9 which pass through a ratchet mechanism on the platform and extend well above the platform when the cross beam 3 and turbines 1 are at their highest position 10 for maintenance, In use, the cross beam 3 and turbines 1 are lowered to their operative position 11 below the surface of the water. The platform 6 is above the highest expected water level 8 and the turbine control system, pitch control drive system and power electronics are located in this part of the structure, rather than below the sea surface. The tower 5 is supported on struts 7 fixed to the sea bed. The construction involves installing the tower onto the pile, bringing the crossbeam down onto the tower and then bolting the platform, or topside stmcture, to the tower. The powertrains are assembled and bolted on to the crossbeam last, However, there is a requirement for sub-sea turbines to be installed in locations where tower mounting is not suitable. In this case, the design of a frilly submerged turbine cannot make use of the tower and lift legs as a method for putting the powertrain and turbine assemblies into place, Instead, piles are installed on the sea bed and a means for lowering, locating and locking the assemblies onto the piles is required. Methods exist for subsea location of items deep in the ocean, such as described in W02012 118383 which describes installing a sub-structure on the sea bed having a saddle into which a nacelle of a turbine is lowered down guiding wires, extending between the sub-structure and a vessel. The nacelle is provided with support pins which interact with slots in the saddle. However, this is relatively complex requiring each support pin to be positioned in the correct slot as the nacelle is lowered into the saddle.

The present invention provides a combined guide and connector whereby the turbine assembly is mounted to the top of the pile. The pile is installed first and a single powertrain is installed onto the pile, avoiding the need for the tower, crossbeam or top side structure required in the example of Fig.]. The piles are installed on the sea-bed using conventional techniques, such as digging a hole for the pile, lowering in the pile and pouring concrete into the pile to anchor it, As illustrated in Fig.2, deployment of pile mounted sub-sea turbines may carried out by lowering the turbine from a supply vessel or barge. In this example, a sub-sea turbine assembly 30, comprising the powertrain in a housing 21, a turbine hub 2 connected to the power train at one end of the housing and turbine Nades 20 fixed to the hub, is supported at the end of a crane jib 22 on a vessel 23 and lowered into position beneath the sea surface 3 1 on a cable 24 connected to a lifting point 25 in an upper part of the housing. The pile 28 is typically cylindrical, although other forms may be used, for example to smooth flow past the pile. A recess is formed in the top end 27 of the pile to co-operate with an appropriately shaped extension 26 in a bottom part of the housing 21.

In this example, described in more detail with respect to Figs.3 to 5, the recess 27 in the top end of the pile has a tapered form which corresponds in shape to that of the extension 26. In an alternative example, shown in Figs.6a and 6b, the connector may be constructed with a recess in the housing which is lowered down over an upper part of the pile.

An example of a connector according to the present invention is shown in more detail in Fig. 3. The recess 27 in the pile 28 is provided with a tapered lip 32 around its uppermost circumference to assist in guiding the extension 26 into place. Machined into an inner surface of the pile, just below the bottom of the lip, are a plurality of circular indentations 33, substantially evenly spaced about a circumference of the pile, all at the same level, An alternative arrangement, equally applicable to the examples of Figs. 3 and 6 is to offset the balls 29 and recesses at two different levels 33 each about a circumference of the cylinder, as shown in Figs7a and 7b, The balls and recesses may partially overlap as shown in Fig.7b, or be in wholly distinct bands as in Fig.7a.

The length of an insert 37 of the extension 26, described in more detail below, is adapted accordingly, so that the insert 37 is in contact with all of the balls when the powertrain is fully seated. The offset at different levels allows for closer spacing between adjacent balls, without a significant increase in the height over which the recesses are formed. The extension 26 is formed as an insert having a tapered portion with a reduced circumference at its end remote from the lifting eye 25 to help direct the insert into the opening of the pile and a substantially cylindrical body. In the situation where the pile was not cylindrical, with a circular cross-section, then the cross section of the recess 27 and extension 26 may be adapted to match that of the pile, or alternatively the recess is formed in a cylindrical body attached to the top of the pile.

In the main body of the extension 26, a number of balls 29 protrude through openings 39, as indicated in Fig.4. The openings 39 have the same circumferential spacing and arrangement as the circular indentations 33 in the inner surface of the pile.

The lifting eye 25 is formed in the power train housing 21 and the insert 37 of the connector is bolted to the powertrain housing 21 via coupling 47. Although welding or casting with the housing would be possible, this complicates manufacture and bolting the insert to the powertrain housing is preferred. Retaining clips 34 may be provided which clip into place beneath a retaining lip 38 on the extension 26, above the line of ball openings 39 to hold the insert 37 in position relative to the extension 26 whilst it is being lifted and lowered, Fig.4 shows a section through the connector, The extension 26 is a hollow housing with openings 39 in a wider section 40 and with a narrow, hollowed out section 41 below the openings. The wider section 40 allows balls 29 to move freely between an inner surface 42 of the extension 26 and a first section 43 of the insert 37. A second section 44 of the insert has an outer cross-section which corresponds to the inner cross-section of the wider section 40 of the extension.

Figs.Sa to 3d illustrate how the connector operates to locate the extension 26 of the housing 21 in the top of the pile and how it allows the turbine assembly to be removed. The turbine assembly including extension 26 is lowered into position under as the effect of gravity and the tapered end 45 is guided by the tapered lip 32 into the recess 27 at the top of the pile 28, The insert 37 is in its raised position and the balls 29 have space to move between the lower part 43 of the insert and the upper wall 42 of the extension. As can be seen from Figs. Sb and Sc, this relative positioning of the insert 37 and the extension 26 is maintained as the extension moves further into the recess 27.

Finally, the bottom of the tapered section 45 is in contact with the bottom 46 of the S recess 27. As the crane continues to lower the turbine assembly, the frill weight of the the powertrain in its housing comes onto the insert 37 and pushes this down, the edge 36 of the insert forcing the balls laterally outward into the ball recesses 33 in the pile.

The effect of this is to lock the whole assembly into the pile as shown in Fig.Sd. No further locking mechanism is required. In order to remove the turbine assembly, for example for maintenance, the cable is re-attached to the lifting eye and the weight taken off the insert 37 until it is lifted up sufficiently that the balls 29 can move back into the body of the extension from their position in the pile ball recesses 33 and the extension is lifted out of the pile recess.

In an alternative embodiment, the individual circular recesses 33 in the inner IS surface of the pile 28 may be replaced by a continuous groove around the inner circumference at the same location. This allows the powertrain and turbine assembly to yaw. However, this embodiment would only be useful where the currents vary in direction over the course of a tide, For a situation where there is a clear ebb and flood tide and little time where the direction of the current is significantly out of alignment with the fore and aft alignment of the assembly on the pile, then variable pitch blades on the turbine allow for power generation in both directions without the need for more finely adjustable alignment of the whole assembly to the current flow direction, Fixing the pile in place as described with respect to the first embodiment has the benefit of reducing wear caused by the relative movement of the pile and extension in use.

Figs.6a and 6b illustrate an alternative arrangement, based on the same principle, The top 48 of the pile 28 is shaped to have a frusto-conical top, with indentations 51 to receive the balls 29. A connector housing 49 is loosely connected to the powertrain housing 21, for example by chains (not shown) to hooks 54 and shaped to pass around the upper cylindrical section of the pile and be supported by the top of the frusto-conical section. The connector housing 49 has orifices 50 to allow the balls to partially pass through into contact with the indentations 5 1 and is shaped such that when in position on the top of the pile, the balls within the housing cannot drop below the level of the orifices 50, As can be seen in Fig,6b, an insert 52, mounted to the powertrain housing by lifting point 55, is lowered down within the connector housing 49 as the powertrain is lowered and pushes the balls 29 outward, so that they extend partially through the orifices 50 and come into contact with indentations in the surface of the pile, locking the housing to the pile from the outside. The present invention has a number of advantages over existing ways of connecting turbine assemblies in sub-sea locations. By shaping tapering the connector and the pile with corresponding tapers, final location of the turbine assembly on the pile is simplified. Using the weight of the powertrain which pushes a cam in the downward direction, pushing the locking balls outwards into the pile column to lock the extension of the housing into the pile, the turbine assembly is able to be locked into position, yet easily removed without additional cables or fittings which might require a diver or ROV to install and remove, by lifting the assembly and so taking the weight off, allowing the balls to move back into the body of the extension and so unlock the connector for removal of the assembly.

The design of pile column with recesses to take the balls in and effectively lock the extension may be adapted by converting the individual recesses into a continuous groove in the inner surface of the pile, so that the entire turbine assembly may yaw, if required.

The present invention provides a combination of functions which increase the flexibility and ease of installation of the powertrain and turbine assembly. The installation is simplified by removing many of the procedures in the locating and locking phases. The removal phase is greatly improved as the hook is simply attached to the top of the structure and as it is lifted, the lock is released.

Claims

CLAIMSL A two part connector comprising a hollow body, an insert and a plurality of balls in a first part; and in a second part, one or more indentations adapted to contact the balls; wherein the insert is adapted to move between an open position out of contact with the balls and a closed position in contact with the balls.
2. A connector according to claim 1, wherein the balls are located between the insert and the indentations.
3. A connector according to claim or claim 2, wherein the hollow body is located between the balls and the indentations.
4. A connector according to any preceding claim, wherein the hollow body is provided with circular openings having a circumference less than the circumference of the balls.
5. A connector according to claim 4, wherein a cross section of each of the first and second part is circular.
6. A connector according to claim 5, wherein adjacent circular openings are located on the same circumference of the hollow body.
7. A connector according to claim 5, wherein the indentation comprises a continuous groove.
8. A connector according to claim 7, wherein the connector comprises two parallel indentations.
9. A connector according to any preceding claim, wherein the first part comprises a pile.
10. A connector according to any preceding claim, wherein the indentations are formed in the inner surface of the pile.
11. A connector according to any preceding claim, wherein the hollow body comprises an extension of a turbine powertrain housing.
U, A sub-sea turbine installation comprising a turbine powertrain, a sub-sea mounting and a connector according to any preceding claim.
13. A method of installing a sub-sea turbine assembly, the method comprising providing a pile with one or more indentations; providing an extension of a turbine assembly housing, the extension comprising a hollow body, an insert and a plurality of balls; lowering the sub-sea turbine assembly on a lowering device towards a sub-sea pile until the hollow body and the pile come into contact; continuing to lower the insert, such that the insert pushes the balls into contact with the indentations; and disconnecting the turbine assembly from the lowering device.
14. A method of retrieving a sub-sea turbine assembly having an extension of a turbine assembly housing comprising a hollow body, an insert and a plurality of balls from a pile with one or more indentations; the method comprising connecting the turbine assembly to a lifting device; lifting the turbine assembly until the insert is raised sufficiently to allow the balls to move out of contact with the indentations; and continuing to lift the turbine assembly off the pile.Amendments to the claims have been filed as followsCLAIMSL A two part connector comprising a hollow body, an insert and a plurality of balls in a first part; and in a second part, one or more indentations adapted to contact the balls; wherein the insert is adapted to move between an open position out of contact with the balls and a closed position in contact with the balls; wherein the hollow body is located between the balls and the indentations.2. A connector according to claim 1, wherein the balls are located between the insert and the indentations.3. A connector according to claim 1 or claim 2, wherein the hollow body is provided with circular openings having a circumference less than the circumference of the balls.IC) is 4. A connector according to claim 3, wherein a cross section of each of the first and second part is circular.5. A connector according to claim 4, wherein adjacent circular openings are located on the same circumference of the hollow body.6. A connector according to claim 4, wherein the indentation comprises a continuous groove.7. A connector according to claim 6, wherein the connector comprises two parallel indentations.S. A connector according to any preceding claim, wherein the first part comprises a pile.9. A connector according to any preceding claim, wherein the indentations are formed in the inner surface of the pile.10. A connector according to any preceding claim, wherein the hollow body comprises an extension of a turbine powertrain housing.11. A sub-sea turbine installation comprising a turbine powertrain, a sub-sea mounting and a connector according to any preceding claim.U, A method of installing a sub-sea turbine assembly, the method comprising providing a pile with one or more indentations in its inner surface; providing an extension of a turbine assembly housing, the extension comprising a hollow body, an insert and a plurality of balls, wherein the hollow body is located between the balls and the indentations; lowering the sub-sea turbine assembly on a lowering device towards the pile until the hollow body and the inner surface of the pile come into contact; continuing to lower the insert, such that the insert pushes the balls into contact with the indentations; and disconnecting the turbine assembly from the lowering device, IC) is 13. A method of retrieving a sub-sea turbine assembly having an extension of a r turbine assembly housing comprising a hollow body, an insert and a plurality of balls from a pile with one or more indentations in its inner surface, wherein the hollow body is located between the balls and the indentations; the method comprising connecting the turbine assembly to a lifting device; lifting the turbine assembly until the insert is raised sufficiently to allow the balls to move out of contact with the indentations; and continuing to lift the turbine assembly off the pile,