HIGH VOLTAGE ELECTRIC SWIVEL ARRANGEMENT

Abstract

A swivel arrangement including high voltage electrical swivels concentrically arranged around a common axis, each swivel including: a first annular housing part and a second annular housing part together defining an internal annular volume; a first solid electrical conductor stationary with respect to the first annular housing part, and a second solid electrical conductor stationary with respect to the second annular housing part, wherein the first and second electrical conductors are arranged within the internal annular volume for making conductive sliding contact with each other, wherein the first annular housing part and second annular housing part are rotatable relative to each other around the common axis while the first and second electrical conductors are in sliding contact with each other; wherein the swivels are arranged concentrically around the common axis so that a plane normal to the axis intersects at least two, preferably three, of the electrical swivels.

Claims

1. A swivel arrangement comprising a plurality of high voltage electrical swivels arranged around a common axis, each high voltage electrical swivel comprising: a first annular housing part and a second annular housing part together defining an annular interior volume; a first solid electrical conductor stationary with respect to the first annular housing part, and a second solid electrical conductor stationary with respect to the second annular housing part, wherein the first and second electrical conductors are electrically isolated from the first and second housing parts and are arranged within the internal annular volume for making conductive sliding contact with each other; wherein the first annular housing part and second annular housing part of each electrical swivel are rotatable relative to each other around said common axis while the first and second electrical conductors thereof are in sliding contact with each other; wherein the first and second annular housing parts of the plurality of swivels together define a central through opening through which the common axis extends; and wherein the electrical swivels are arranged concentrically around the common axis in such a manner that a plane normal to said axis intersects at least two of the electrical swivels.

2. The swivel arrangement according to claim 1, wherein the second annular housing parts of the swivels are adapted for rotating independently from each other around the common axis.

3. The swivel arrangement according to claim 1, wherein for each of said swivels the first housing part and the second housing part substantially close off the interior volume.

4. The swivel arrangement according to claim 1, wherein for each of said swivels the first housing portion is formed as a substantially U-shaped ring having a circumferential base and two circumferential legs having facing sides which extend from the base.

5. The swivel arrangement according to claim 4, wherein the second housing part comprises a circumferential section which is arranged at least partially between the facing sides of the two legs for substantially closing off the interior volume.

6. The swivel arrangement according to claim 1, wherein the first conductor is formed as a ring provided with louvers for contacting a facing side of the second conductor, or wherein the second conductor is formed as a ring provided with louvers for contacting a facing side of the first conductor.

7. The swivel arrangement according to claim 1, wherein when seen in projection onto a plane parallel to and through the common axis, all swivels of the plurality of swivels at least partially overlap.

8. The swivel arrangement according to claim 1, wherein the plurality of high voltage electrical swivels are or comprise monophasic swivels.

9. The swivel arrangement according to claim 1, wherein the first and/or second electrical conductor has an annular shape with a center axis substantially coinciding with the common axis.

10. The swivel arrangement according to claim 1, wherein each swivel further comprises one or more bushings or roller bearings via which the first annular housing part is rotatably supported on the second annular housing part.

11. The swivel arrangement according to claim 1, each swivel further comprising two spaced apart seals between the first housing part and the second housing part.

12. The swivel arrangement according to claim 1, wherein the first annular housing part comprises a plurality of detachably connected annular sector portions which together from the first annular housing part, and wherein the second housing part comprises a plurality of detachably connected annular sector portions which together form the second annular housing part.

13. Method for mounting a swivel arrangement according to claim 1 around a tube for transporting a liquid, the method comprising: arranging a first swivel of said swivel arrangement according around the tube; subsequently arranging a second swivel of said swivel arrangement concentrically around the first swivel in such a manner that a plane normal to the common axis intersects the first and second swivel.

14. The method according to claim 13, further comprising: subsequently arranging a third swivel of the swivel arrangement concentrically around the second swivel in such a manner that the plane normal to the common axis intersects the first, second and third swivel.

15. Method for mounting a swivel arrangement according to claim 1 around a tube for transporting a liquid, the method comprising: arranging a first swivel of said swivel arrangement according around the tube; subsequently arranging a second swivel of said swivel arrangement concentrically around the first swivel in such a manner that a plane normal to the common axis intersects the first and second swivel, wherein the first annular housing part comprises a plurality of detachably connected annular sector portions which together from the first annular housing part, and wherein the second housing part comprises a plurality of detachably connected annular sector portions which together form the second annular housing part, and wherein arranging the first and second swivels around the tube comprises placing sectors of the first and/or second annular housing portions of said swivels around the tube and fixing the corresponding sectors of the first and/or second annular housing portions of each of said swivels with respect to each other.

16. The swivel arrangement of claim 1, wherein the plane normal to the axis intersects at least three of the electrical swivels.

17. The swivel of claim 9, wherein, in each swivel, the first and second electrical annular conductors are arranged for contacting each other substantially in a plane normal to the common axis.

18. The swivel arrangement according to claim 2, wherein for each of said swivels the first housing part and the second housing part substantially close off the interior volume.

19. The swivel arrangement according to claim 2, wherein for each of said swivels the first housing portion is formed as a substantially U-shaped ring having a circumferential base and two circumferential legs having facing sides which extend from the base.

20. The swivel arrangement according to claim 3, wherein for each of said swivels the first housing portion is formed as a substantially U-shaped ring having a circumferential base and two circumferential legs having facing sides which extend from the base.

Description

SHORT DESCRIPTION OF DRAWINGS

[0032] The present invention will be discussed in more detail below, with reference to the attached drawings, in which

[0033] FIG. 1A schematically shows an isometric partially cut-away view of a swivel arrangement according to the invention, and FIG. 1B shows a top view thereof;

[0034] FIGS. 2A and 2B schematically shows a cross-sectional view of part of a swivel as used in a swivel arrangement according to the invention, and a detail of section IIB thereof;

[0035] FIG. 3 shows a flow chart of a method according to the invention.

DESCRIPTION OF EMBODIMENTS

[0036] FIGS. 1A and 1B respectively show a partially cut-away isometric view of a swivel arrangement 1 according to the invention, comprising three annular swivels 100, 100′, 100″ arranged concentrically around a common axis Y. The swivels are arranged concentrically, rather than vertically, in such a manner that the three swivels 100, 100′, 100″ are intersected by a common plane N which is normal to the axis Y. Addition of further swivels is thus possible without increasing the height of the arrangement along the direction Y. The swivels are arranged around a central through opening which extends through the arrangement and through which a tube, such as risers or the like, may extend.

[0037] In FIGS. 1A and 1B the arrangement is shown in a partially cut away fashion, to allow a view of the interior volume V of swivel 100. The swivel 100 comprises a first annular housing portion 110 which has a U-shaped cross-section, the U-shape having a base 100a which extends substantially parallel to the plane N, the base further having two legs 100b, 100c which face each other and extend from the base substantially parallel to the axis Y. At an upper side of the first housing portion 110, a second housing portion 120 is arranged, which is partially arranged between the facing legs 100b, 100c to close off the interior volume V. The second housing portion is supported via roller bearings (not shown) on the first housing portion 110, allowing rotation of the second housing portion relative the first housing portion around the axis Y. Though not shown in the example of FIG. 1A, it will be clear that instead of roller bearings a sleeve bearing or bush or the like could be used.

[0038] First housing portions 110′, 110″ of swivels 100′ and 100″ are fixed with respect to the first housing portion 110 of swivel 100. In the embodiment shown, at least during mounting of the arrangement on a vessel, the second housing portions 120, 120′, 120″ may rotate independent from each other around the common axis Y. However, it will be appreciated that instead the second housing portions may be rotationally fixed with respect to each other, or that the second housing portions may be fixed with respect to each other once the swivel arrangement 1 has been mounted on a vessel.

[0039] Though the swivels 100, 100′, 100″ have different diameters, they are constructed in similar manner, the swivels each having an annular interior volume V, V′, V″. Within the volume V, a first annular electrical conductor 130 is arranged stationary with respect to the first housing portion 110, and supported electrically isolated on and spaced apart from the first housing portion on electrically isolating pins 139. Likewise, a first annular electrical conductor 140 is arranged within the volume V and arranged stationary with respect to the second housing portion and attached by electrically isolating pins 149 to the second housing portion 120. During rotation of the first housing portion relative to the second housing portion, facing sides of the first and second conductors 130, 140 remain in contact with each other to provide a rotatable high voltage (i.e. 3 kV or more) electrical contact between the two conductors. At a lower side of the first housing part a first connector 132 is provided which extends from the exterior of the swivel 100, through the base 110, to the interior volume where the connector is electrically connected with the first conductor 130. At an upper side of the second housing part a second connector 142 is provided which extends there through, electrically connects to the second conductor 130. The first and second connectors 132, 142 can be attached to conductive cables or the like. Swivels 100′ and 110″ are provided with such connectors as well.

[0040] The interior volumes V, V′, V″ are typically filled with an insulating fluid in such a manner that both the first and second conductors are completely submerged by the fluid. In order to facilitate supply of insulating fluid to interior volume V″, a fluid inlet port 145 is provided which is generally closed except when isolating fluid is supplied therethrough into the interior volume V′″. The port lies completely at a height above both the first and second electrodes, so that if the fluid is a liquid that has reached the level of the port, the first and second electrodes are completely submerged in the isolating fluid.

[0041] The top view of FIG. 1B shows more clearly that each of the swivels is constructed from a number of first and second housing portion segments. First housing portion 110 comprises 6 annular sector portions, of which portions 111,112,113,114,115 are indicated, which together form the annular first housing portion 110. The second housing portion 120 also comprises 6 annular sector portions, of which portions 122, 123, 124 and 125 are shown, and which together from the annular second housing portion 120. By constructing the swivels sector by sector, the swivels can be mounted around tubes, such as risers of a vessel, without having to move the tube and without having to slide the swivels over an end of the tube along the longitudinal direction of the tube. Connector plates 165 are provided between sector portions 123 and 124 to allow these portions to be bolted together. The sector portions 122 and 125 are provided with connector plates as well, to allow these to be bolted to two respective adjacent sector portions that are not shown partially cut-away views of in FIGS. 1A and 1B. In the example shown, sector portions 122 and 123 are connected to each other by welding, as are sector portions 124 and 125. When seen in projection onto a plane P, which is parallel to the common axis Y and extends through said common axis Y, the swivels 100, 100′ and 100″ at least partially overlap each other.

[0042] FIG. 2A shows a detailed cross-sectional side view of part of swivel according 100 to the invention. The first housing portion 110 has a substantially U-shaped cross-section, with a base 110a that extends normal to axis Y, and with two legs 110b, 110c that extend from the base in a direction parallel to the axis Y. The second housing portion 120 comprises a portion 120a that fits between the facing legs 110b,110c and substantially closes off the interior volume V, so that an isolating liquid L is contained by the first and second housing portion. In FIG. 2A, the first and second conductors are completely submerged by the isolating liquid L, and a conductive rod 142a extends from the connector 142 through the isolating liquid L and conductively connects the connector to the second conductor 140. Though not shown in FIG. 2A, the first conductor 130 is conductively connected in a similar fashion to connector 132.

[0043] The second housing portion further comprises an inner circumferential flange 120b and an outer circumferential flange 120c. A first set of bearings 160 is arranged at an inner circumference of the swivel 100 between the inner circumferential flange 120b and the inner leg 110b, and a second set of bearings 161 is arranged at an outer circumference of the swivel between the outer circumferential flange 120c and the outer leg 110c. A first circumferential seal 170a is partially arranged in a corresponding inner circumferential groove of portion 120a, and second circumferential seals 171a, 171b that are partially arranged in respective outer circumferential grooves 173a,173b of portion 120c, together seal of the interior volume. A detail of the second circumferential seals 171a,171b is shown in FIG. 2B.

[0044] FIG. 3 schematically shows a flowchart of a method 300 of the invention, for mounting a swivel arrangement around one or more tubes. The one or more tubes may for instance comprise risers of an FPSO. First, in step 310 a first swivel of a swivel arrangement of the invention as described herein is arranged around the tube. Next in step 320 a second swivel of a swivel arrangement of the invention is arranged concentrically around the first swivel, in such a manner that a plane normal to the common axis intersects the first and second swivel. Though the respective first housing portions of the first and second swivel will be fixed with respect to each other, during mounting the second housing portions may be rotatable independent from each other around the common axis.

[0045] Optionally, a step 330 is carried out, in which a third swivel of a swivel arrangement is arranged concentrically around the second swivel in such a manner that the plane normal to the common axis intersects the first, second and third swivel.

[0046] When the housing portions of the first, second and/or third swivel are formed as annular sectors, the first, second and/or third swivel may conveniently be around the tube without having to be guided over a top or lower end of the tube.

[0047] Also optionally, once the entire swivel arrangement has been mounted around the one or more tubes, the second housing portions of the swivels may be fixed with respect to each other.

[0048] In summary, the invention relates to a swivel arrangement comprising a plurality of high voltage electrical swivels concentrically arranged around a common axis, each swivel comprising: a first annular housing part and a second annular housing part together defining an annular interior volume; a first solid electrical conductor stationary with respect to the first annular housing part, and a second solid electrical conductor stationary with respect to the second annular housing part, wherein the first and second electrical conductors are arranged within the annular interior volume for making conductive sliding contact with each other, wherein the first annular housing part and second annular housing part are rotatable relative to each other around said common axis while the first and second electrical conductors are in sliding contact with each other; wherein the swivels are arranged concentrically around the common axis in such a manner that a plane normal to the axis intersects at least two, preferably at least three, of the electrical swivels. The swivel arrangement may comprise or form a stack of the swivels in a concentric arrangement.

[0049] The present invention has been described above with reference to a number of exemplary embodiments as shown in the drawings. Modifications and alternative implementations of some parts or elements are possible, and are included in the scope of protection as defined in the appended claims.