Wind turbine nacelle cover

Abstract

A nacelle bottom cover part (32) for the underside of a wind turbine nacelle is formed with a number of shallow receptacle regions for containing liquid leaked or spilled from turbine components. Overflow channels (88,90,92) may be provided between the receptacle regions so that leaked liquid can flow between receptacle regions.

Claims

1. A cover part for the underside of a wind turbine nacelle, comprising: a number of individual interconnected panels, each panel formed with a number of receptacle regions, wherein the number of receptacle regions is configured to be associated with respective operative components in the wind turbine nacelle for containing liquid leaked or spilled from the operative components, wherein adjacent interconnected panels are connected at overlapping edge regions; and wherein flow channels are provided between the receptacle regions so that liquid can flow between them.

2. The cover part according to claim 1 wherein each of the panels is defined at least in part by upstanding rims.

3. The cover part according to claim 2 wherein the flow channels are constituted by regions of reduced height provided in the upstanding rims.

4. The cover part according to claim 2 wherein the flow channels are provided by openings in the upstanding rims.

5. The cover part according to claim 2 wherein the upstanding rims include an upstanding portion and a flange portion extending from the upstanding portion, wherein the overlapping edge regions include overlapping flange portions, and wherein the flow channels are formed in the overlapping flange portions.

6. The cover part according to claim 1 comprising a first receptacle region configured to lie beneath a gearbox in the wind turbine nacelle.

7. The cover part according to claim 1 comprising a second receptacle region configured to lie beneath a generator in the wind turbine nacelle.

8. The cover part according to claim 1 comprising a third receptacle region configured to lie beneath one more hydraulic accumulators in the wind turbine nacelle.

9. The cover part according to claim 1, wherein each receptacle region is dimensioned to receive between 100 and 400 litres of liquid.

10. The cover part according to claim 1, wherein the receptacle regions are dimensioned to receive in combined total at least 1000 litres of liquid.

11. The cover part according to claim 1 wherein the receptacle regions are provided with drain holes fitted with plugs or valves to allow liquid to be drained therefrom.

12. A wind turbine nacelle having a cover part according to claim 1.

13. A wind turbine having a nacelle fitted with a cover part according to claim 1.

14. A wind turbine comprising: a nacelle; operative components including a gearbox and generator disposed within the nacelle; and a nacelle cover coupled to the nacelle and having a bottom cover part formed with a number of receptacle regions which underlie and are associated with respectively the gearbox and generator, and wherein flow channels are provided between the receptacle regions so that liquid can flow between them.

15. The wind turbine according to claim 14 wherein the number of receptacle regions includes a first receptacle region having a first upstanding rim which circumscribes the gearbox and a second receptacle region having a second upstanding rim which circumscribes the generator.

16. The wind turbine according to claim 15 wherein the number of receptacle regions includes a third receptacle region having a third upstanding rim which circumscribes one more hydraulic accumulators.

17. The wind turbine according to claim 14 wherein the cover part is formed by a number of individual interconnected panels where the receptacle regions are defined in some or all of the panels.

18. The wind turbine according to claim 17 wherein the panels are connected at overlapping edge regions.

19. The wind turbine according to claim 14 wherein the receptacles are defined at least in part by upstanding rims.

20. The wind turbine according to claim 19 wherein the flow channels are constituted by regions of reduced height provided in the upstanding rims.

21. The wind turbine according to claim 19 wherein the flow channels are provided by openings in the upstanding rims.

22. The wind turbine according to claim 14 wherein the receptacle regions are provided with drain holes fitted with plugs or valves to allow liquid to be drained therefrom.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will now be further described by way of example only and with reference to the accompanying figures in which:

(2) FIG. 1 is a front view of a wind turbine;

(3) FIG. 2 is a perspective view of the exterior of a wind turbine nacelle;

(4) FIG. 3 shows a bottom cover of the nacelle, with end part separated;

(5) FIG. 4 shows a main part of the bottom nacelle cover;

(6) FIG. 5 is an enlarged detail of a rim of a first receptacle region showing a flow channel lip between first and second receptacle regions;

(7) FIG. 6 is a view of a the main part of the bottom cover with the individual cover part sections separated;

(8) FIG. 7 shows a first cover section of the bottom cover;

(9) FIG. 8 is an enlarged detail of a rim of the second and third first receptacle regions showing a flow channel lip therebetween;

(10) FIG. 9 shows an alternative embodiment with flow openings in the rims between receptacle regions;

(11) FIG. 10 shows a detail of a flow opening of FIG. 9; and

(12) FIG. 11 shows the bottom cover part and location of main turbine components relative to receptacles.

DETAILED DESCRIPTION

(13) FIG. 1 illustrates a modern utility scale wind turbine 10 comprising a tower 11 and a wind turbine nacelle 12 positioned on top of the tower 11. The wind turbine rotor 13, comprising three wind turbine blades 14, is supported by the nacelle 12 through a main low speed shaft (not shown) which extends out of the front of the nacelle 12. The tower 11 is supported on and secured to the wind turbine foundation 15. The main rotor shaft extends into or is connected to a speed increasing gearbox, the output of which is provided to a generator for converting the rotation of the rotor 13 into electrical current. The wind turbine typically includes other operative components, such as other items of power handling equipment, converters, transformers and the like.

(14) Various of these operative components may contain liquid for cooling and/or lubricating purposes. For example, gearboxes typically contain lubricating oils which are contained in or circulated in the gearbox casing and supplied to various points in the gearbox, bearings etc. The generator is provided with circulated cooling liquid, usually water. A hydraulic circuit may be provided for operation of rotor pitch adjustment, with hydraulic accumulators arranged within the nacelle. The power handling equipment typically includes a transformer, and these require a means of cooling, which may with certain designs include circulated cooling liquid such as cooling oil. Although major leakage of liquid from such components is unlikely, failure of a sub-component such as a seal can occasionally give rise to liquid leakage. Such might arise during transport to the installation site (the nacelle typically being transported in an assembled condition) or during operation or service of the wind turbine. Leaked liquid can potentially damage other turbine components and create a hazard for personnel and for the environment. Furthermore, such leaked liquid may be time consuming and expensive to clean up. Accordingly, there is need for a structure which can contain liquid leaked or spilled within the turbine nacelle. As discussed further below, such is achieved through adaptations to the nacelle bottom cover.

(15) FIG. 2 illustrates the exterior of a wind turbine nacelle 12. As noted above the nacelle 12 houses the main operative components of the turbine. The nacelle comprises a main load-bearing frame (not visible) onto which are directly or indirectly mounted the main operative components. The nacelle 12 is provided with an external nacelle cover 20 which encloses the operative components and provides protection from the environment, rain, wind, moisture, salt, dust etc. The nacelle cover comprises a number of cover parts which are mounted on an internal frame which is itself connected indirectly or directly to the internal main frame. In the structure as illustrated the cover parts are arranged to provide a generally box-like arrangement, including side covers 22 ends 26, 28, roof cover 30 and bottom cover 32. Each of these parts is constructed from a number of individual panels. Sealing gasket structures are provided between abutting or overlapping panel edges, as well as between complete panel sections to ensure that the nacelle provides a substantially weatherproof environment. The panels are preferably formed of a light relatively rigid structure such as glassfibre reinforced plastics, formed into the desired configuration by moulding.

(16) As can be seen in FIG. 3 the bottom cover 32 comprises a number of sections where each section itself is formed of one or more individual panels, more particularly a front section 34, tower section 35, main section 36 and rear section 38 (where “front” refers to the end of the nacelle at which the rotor is mounted and which in operation faces into the wind and “rear” to the opposite end). Front 34 and rear sections 38 are both preferably single panels which are unitary structures. The tower section 35 comprises a number of individual panels including a front tower panel section 35A and two rear tower panel sections 35B and 35C, which together define a circular opening 40 through which in use the yaw components situated between tower top and nacelle extends.

(17) The main bottom cover section 36 is formed of a number of interconnected individual panels, including first, second, third and fourth panels 42, 54, 56 and 66 respectively. These constitute liquid-receiving receptacles as is now discussed in more detail. More particularly, first panel 42 defines a first receptacle. As best seen in FIGS. 6 and 7 this is formed to have a concave shallow tray-like form with floor 43 and shallow inclined opposite edges regions 44, 46 on opposite lateral sides, a front upstanding rim 48, and a rear upstanding rim 50. A forward edge region 52 is formed with holes to receive fixings, bolts or the like, for securing to rear edges of the rear tower panel sections 35B and 35C, whereby connection can be made thereto in overlapping manner. A fixing boss 53 is formed in the rim 50, by which attachment can be made to a cover support frame (not shown) which is itself connected to the nacelle main frame. An internal bushing is provided on the underside of the fixing boss 53 into which a fixing bolt is screwed.

(18) The entire panel 42 is preferably a thin-walled unitary moulded structure for ease of manufacture and assembly, including the upstanding rims and other described structures, bosses etc. Alternatively however the rims might be separate upstanding wall structures secured to the panels by adhesive or fixings.

(19) To the rear of first panel 42 are connected the second and third panels 54 and 56 arranged side by side, constituting second and third receptacles respectively. Second panel 54 is likewise formed to have a concave shallow tray-like form with floor 55, an upstanding front rim 58 at which it is connected to the first panel 42, a shallow inclined edge region 60 at a lateral side, a side upstanding rim 62 at which it is connected to third panel 56 and a rear upstanding rim 64 at which it is connected to the fourth panel 66. A pair of fixing bosses 65 are provided at rim 62 by which attachment can be made to the cover support frame (not shown) which is itself connected to the nacelle main frame. Internal bushings are provided on the underside of the fixing bosses 65 into which fixing bolts are screwed.

(20) Third panel 56 is likewise formed to have a concave tray-like form with a floor 57, an upstanding front rim 68 at which it is connected to the first panel 42, a shallow inclined edge region 70 at a lateral side, a side upstanding rim 72 at which it is connected to the second panel 54 and a rear upstanding rim 74 at which it is connected to the fourth panel 66. A pair of fixing bosses 75 (see FIG. 8) are provided at rim 72, by which attachment can be made to the cover support frame (not shown) which is itself connected to the nacelle main frame. A further pair of fixing bosses 76 are provided at the opposite side of the panel 56 adjacent the inclined edge 70. Internal bushings are provided on these fixing bosses into which fixing bolts are screwed.

(21) Fourth panel 66 is likewise formed to have a concave tray-like form with a floor 78, front rim 80 at which it is connected to the second and third panels, shallow inclined edge regions 82, 84 at opposite lateral sides, and a rear upstanding rim 86 at which it is connected to the rear panel 38.

(22) As can be seen in FIGS. 4 to 8 the adjacent rims of the panels at which the panels abut each other are formed with overlapping structures at which they are connected, by suitable fixings, bolts or the like. For example, rear rim 50 of the first panel 42 has an upstanding portion and a horizontally rearwardly-extending flange 51. Front rim 58 of the second panel has an upstanding portion and a forward extending flange portion 59. As can best be seen in FIG. 5, when interconnected the flange portion 50 overlies the flange portion 59. Fixing holes are provided in the overlapping flange portions into which are provided fixing bolts or screws or other fasteners. Sealing gaskets, such as deformable foam gaskets are provided between the overlapping structures to ensure a liquid tight connection therebetween. Similar arrangements are provided for effecting the connections between the first, second, third and fourth panels 42, 54, 56 and 66 respectively.

(23) As can be seen in FIGS. 4 to 6 and 8 the upstanding rims between first, second and third receptacles are formed with regions of reduced height which constitute flow channels or overflow channels. A first overflow channel 88 is provided in overlapping rear and front rims 50, 59 respectively of first and second panels, allowing flow between first and second receptacles. A second overflow channel 90 is formed in rims 62 and 72 allowing flow between second and third receptacles. A third flow channel 92 is provided in overlapping rims 64 and 80 allowing flow between third and fourth receptacles. The height of these reduced height regions is such that any small amount leakage or spillage is contained in the one receptacle which underlies the leaking component thereby preventing its escape to elsewhere in the turbine where it might damage other components or equipment or present a hazard to personnel or environment. From there the liquid can be safely removed and disposed of by service personnel. In the event of a significant leakage which fills a particular receptacle, liquid can then flow via the defined overflow channels between receptacles, such that an adjacent receptacle, and eventually all the receptacles become available to contain leaked liquid. By ensuring that the total combined volume of receptacles is greater than the volume of liquid in any particular operative component (gearbox, generator etc.) it is then ensured that leaked or spilled liquid can be fully contained.

(24) The four receptacle regions defined in first to fourth panels 42, 52, 54 and 66 are associated with different operative components which overlie respective receptacles. FIG. 11 shows schematically the location of certain main components. The main shaft 100 and bearings 102 overlie opening 40. The first receptacle defined in panel 42 underlies the gearbox indicated 104. This receptacle is formed to contain about 330 litres. Third receptacle defined in third panel 56 underlies the generator and is formed to be able to contain about 360 litres. Second receptacle defined in second panel 54 underlies hydraulic accumulators (not illustrated) and is formed to be able to contain about 210 litres. Fourth receptacle defined in fourth panel 66 has no particular component associated therewith, and constitutes a buffer region to receive liquid overflow from other receptacle regions. The combined total volume is in the region of about 1100 litres, which is selected to be able to accommodate the entire liquid volume from the component which has the highest liquid volume, which is typically the gearbox.

(25) In an alternative form as illustrated in FIGS. 9 and 10 the flow channels are formed by means of openings 110 in the upstanding portions of the rims. Depending on the precise construction, the upstanding portions of the overlapping rims may be spaced apart when the flanges abut in which case flow tubes are arranged between the openings. In a further alternative, the openings may be provided towards the base of the upstanding rims, in which case the receptacles effectively fill as one.

(26) In the event of leakage or spillage service personnel will need to enter the wind turbine nacelle and pump out the liquid from the receptacle(s) into containers for safe disposal. The receptacles may also be provided with drain openings at low points therein, closed by plugs or valves to facilitate the draining of leaked liquid from the receptacle regions. FIG. 9 shows a drain opening 112 in the floor 43 of the first receptacle

(27) Although a particular construction of bottom cover is illustrated in which liquid capturing receptacles are formed in separate panels, one panel forming one receptacle, the invention is not so limited, and it will appreciated that other constructions are possible. For example, the entire bottom cover may be formed as a unitary structure. Alternatively, panels may be combined so that fewer individual panels are used. Individual panels may be further subdivided into additional receptacles by the provision of additional walls or rims. Thus, the number of panels and receptacles may be varied. Instead of interconnecting panels at the upstanding rims which define the receptacles, connection may be made at abutting horizontal edges in the floor of a receptacle and the upstanding rims which define the receptacles formed at positions away from the panel edges.

(28) It will be appreciated that various modifications to the embodiments described above are possible and will occur to those skilled in the art without departing from the scope of the invention which is defined by the following claims.