NL2020473B1 - Swivel arrangement and assembly of vessel with swivel arrangement - Google Patents

Abstract

A swivel arrangement comprises an outer fluid line concentrically surrounding at least one inner fluid line, wherein the outer fluid line comprises a first outer fluid line part which by an outer fluid line seal is rotatably con— nected to a second outer fluid line part. Each inner fluid line comprises a first inner fluid line part which by an inner fluid line seal is rotatably connected to a second inner fluid line part. The outer fluid line defines an outer fluid channel which by means of the outer fluid line seal is fully sealed with respect to the surroundings. Each inner fluid line seal is constructed such that it defines a gap which allows a cer— tain amount of fluid communication between an inner fluid channel defined by the respective inner fluid line and a sur— rounding fluid line channel defined by a surrounding fluid line.

Description

Patent center

Θ 2020473

(2?) Application number: 2020473 (22) Application submitted: 22 February 2018

Int. Cl .:

F16L 39/04 (2019.01)

0 Application registered: 0 Patent holder (s): August 29, 2019 Bluewater Energy Services B.V. in Hoofddorp. 0 Request published: - 0 Inventor (s): Clemens Gerardus Johannes Maria van der 0 Patent granted: Wet in The Hague. August 29, 2019 Michiel Cornells Kloosterboer in Haarlem. 0 Patent issued: August 29, 2019 0 Authorized representative: ir. A.R. Aalbers in Amsterdam.

54) Swivel arrangement and assembly or vessel with swivel arrangement

57) A swivel arrangement comprises an outer fluid line concentrically surrounding at least one inner fluid line, featuring the outer fluid line comprising a first outer fluid line part which is rotatably connected to a second outer fluid line part. Each inner fluid line comprises a first inner fluid line part which is rotatably connected to a second inner fluid line part. The outer fluid line defines an outer fluid channel which by means of the outer fluid line seal is fully sealed with respect to the surroundings. Each inner fluid line seal is constructed such that it defines a gap which allows a certain amount of fluid communication between an inner fluid channel defined by the respective inner fluid line and a surrounding fluid line channel defined by a surrounding fluid line.

NL B1 2020473

This patent has been granted regardless of the attached result of the research into the state of the art and written opinion. The patent corresponds to the documents originally submitted.

NL27121

Swivel arrangement and assembly or vessel with swivel arrangement

In a first aspect the present invention relates to a swivel arrangement including an outer fluid line concentrically surrounding at least one inner fluid line, the outer fluid line comprises a first outer fluid line part which by an outer fluid line seal is rotatably connected to a second outer fluid line part, each inner fluid line comprises a first inner fluid line part which is rotatably connected to a second inner fluid line part and that is the outer fluid line defines an outer fluid line which by means of the outer fluid line seal is fully sealed with respect to the surroundings.

The number of inner fluid lines may vary (and thus may be more than one, which then are concentric), depending on the required total number of fluid lines including the outer fluid line. A main field of application or such swivel arrangements related to the connection of subsea pipes (or risers) to piping mounted on a vessel which (for example using a turret mounted in a moonpool and attached to a moored buoy) may weathervane around a substantially vertical axis (eg defined by the turret in the moonpool) under the influence of varying outer conditions (such as current and wind). Examples of such swivel arrangements are known, for example, from US-A5,205,768 and GB-A-2 333 139.

In general the seals used for rotatably connecting the first and second outer fluid line parts are such a quality that the outer fluid line channel is fully sealed with respect to the surrounding environment outside of the swivel arrangement.

It should be noted that in general an absolute seal which does not leak at all is impossible and thus within the context of the present invention the definition of fully sealed generally will also and compass a situation in which the seal is not absolute, but fulfill the conditions required in the respective field to be indicated as eg 4 cubic centimeters of liquid per hour per centimeter or seal diameter, or 1050 cubic centimeters of gas per hour per centimeter or seal diameter (for example for a 40 centimeter seal the maximum leak rate is 0.0000004 % or a 1000 m ³ / h liquid flow). Such an outer fluid line seal will effectively prevent that substantial amounts of the fluid flowing into the outer fluid line will leak to the surroundings.

Likewise the seals used for rotatably connecting the first and second inner fluid line parts will be of such a quality, thus preventing that substantial amounts of the fluid flowing in the respective inner fluid line will leak to a surrounding fluid line (which may be a surrounding other inner fluid line or the outer fluid line).

For ensuring an enhanced reliability, multiple seals may be applied too. Typically also a monitoring for fluids of the space between multiple seals may be carried out for allowing a leak detection.

The above measures complicate the design of the swivel arrangements while increasing the cost.

It is an object of the present invention to provide an alternative design for a swivel arrangement or the above type.

In accordance with the present invention the swivel arrangement is characterized in that each inner fluid line seal is constructed such that it defines a gap which allows a certain amount of fluid communication between an inner fluid channel defined by the respective inner fluid line and a surrounding fluid line channel defined by a surrounding fluid line.

The surrounding fluid channel will be the outer fluid line (in the event that only one inner fluid line is present), but also may be a surrounding other inner fluid line (in the event that more than one inner fluid line is present). The use of such seals which do not fully seal is possible in situations in which the fluid in adjacent fluid channels is the same chemistry, but only differs in state (liquid or vapor) and with respect to conditions such as temperature, pressure and flow capacity. Thus a small leakage of the fluid has no detrimental effects (for example a leakage of a small amount of liquid towards the vaporizer only very slightly will increase the amount of vaporizer flow) and a pressure drop over the seal generally will be sufficient high to avoid a substantial change of the properties of the fluids flowing in the inner and outer fluid lines.

An example is the use of the swivel arrangement for the transfer of bulk LNG (Liquefied Natural Gas) with a trickle LNG flow in an inner fluid line and an LNG vapor return in an outer fluid line. During the cool-down of the LNG system the trickle LNG flow provides the LNG liquid that upon vaporization cools the LNG system. The resulting cold vapors are returned through the annular space or the outer fluid line. In this example, any small leakage from the (trickle flow) inner fluid line to the (vapor return) outer line is allowed as this leaked liquid LNG will also vaporize and will contribute to the cooling down of the LNG system.

The resulting swivel arrangement may thus have a less complicated and less costly design.

The amount of allowed leakage through the inner fluid line seal may vary with the respective demands. As such it is possible that the inner fluid line seal is constructed such that it allows the passage or 0.001 to 10% of the fluid flow passing through the inner fluid line.

In an alternative embodiment the inner fluid line seal is constructed such that it allows the passage or 0.1 to 2% of the fluid flow passing through the inner fluid line.

For arriving at an inner fluid line seal with the required characteristics, a number of options are available. For example, in one embodiment the inner fluid line seal is defined by a gap between overlapping ends or the first and second inner fluid line parts with different diameters. This means that the ends of the first and second inner fluid line parts which have to cooperate for defining the respective in n fluid line seal have different diameters, such that one of these ends can be inserted in the other end while leaving an annular gap between the ends. The difference in diameters (but also the length of the overlap) may be chosen such that a gap with the desired characteristics is obtained.

An additional advantage of such a design of the seal is that it allows a simple assembling and disassembling of the first and second inner fluid line parts, and also allows a relative axial movement between, for example for compensating thermal contractions / expansions.

For further increasing a pressure drop over the seal, it is conceivable that the overlapping ends of the first and second inner fluid line parts define a labyrinth seal.

In an alternative embodiment, between said overlapping ends of the first and second inner fluid line parts a sliding ring is positioned. Such a sliding ring engages both overlapping ends for ensuring a concentric relative rotation between the overlapping ends. There is no need that such a sliding ring fully seals the gap between the overlapping ends and thus the sliding ring may have a simple and less costly design.

In another embodiment the inner fluid line seal is defined by a gap between frontal faces or the first and second inner fluid line parts. The dimension of the gap is one of the factors that determine the leak rate of the seal.

It is conceivable, then, that the frontal faces define ordered, preferably parallel frontal faces. As a result the frontal faces of the first and second inner fluid line parts are separated by an inclined gap or channel. The inclination can be varied for increasing or reducing the length of the gap or channel, thus changing the leak rate of the seal.

In yet another embodiment of a swivel arrangement is provided with a central swivel part which comprises the first and second outer fluid line parts that are connected at one end and are connected by the outer fluid line and include a first connector, and with two outer fluid line sections at opposite sides of the central swivel part each ending in a second connector intended to be connected to a corresponding first connector, the outer fluid line sections support the inner fluid line parts and in an assembled position of the swivel arrangement, in which the outer and inner fluid lines extend substantially vertically, the inner fluid line seal is located at a level below the lower ones or corresponding first and second connectors.

When the swivel arrangement, starting from the assembled position (in which corresponding first and second connectors are connected), has to be disassembled (meaning that the central swivel part has been removed), only an upper one of the outer fluid line sections has to be lifted that far the respective inner fluid line part supported by it is completely moved above the upper ones or corresponding first and second connectors, where after (when the connectors have been disconnected) the central swivel part can be removed sideways without being lifted .

If, however, the inner fluid line seal would be located at a level between the lower ones and the upper ones or the corresponding first and second connectors, not only the upper one or the outer fluid line sections should be lifted as stated before, but also the lower one of said sections should be lowered (or alternatively also the central swivel part should be lifted, as generally will be the case because it is not possible to lower said lower section) until the respective inner fluid line part supported by the lower section is completely moved below the lower ones or corresponding first and second connectors before the central swivel part could be moved sideways. This process is more complicated.

In one embodiment the connectors are flanges intended to be bolted together.

In a second aspect the invention relates to an assembly of vessel provided with vessel mounted fluid lines and a swivel arrangement according to the present invention intended to rotatably connect the vessel mounted fluid lines to fluid lines moving relative to the vessel.

In one embodiment, then, the assembly comprises a moonpool in the vessel, a turret mounted in said moonpool for a rotation relative to the vessel and supporting risers, and a turret mounted swivel arrangement for rotatably connecting the vessel mounted fluid lines to the risers.

Hereinafter the invention will be elucidated while referring to the drawings, in which:

Figure 1 in a schematic longitudinal cross section illustrating a first embodiment of a swivel arrangement;

Figures 2-6 in schematic longitudinal cross sections illustrate different numbers or an inner fluid line seal;

Figure 7 in a schematic longitudinal cross section illustrates a second embodiment of a swivel arrangement in an assembled position, and

Figure 8 in a schematic longitudinal cross section illustrates the second embodiment of a swivel arrangement in a partly disassembled position.

Firstly referring to figure 1, a first embodiment or a swivel arrangement in accordance with the present invention is illustrated. It comprises an outer fluid line 1 which is at least part of its length concentrically surrounds an inner fluid line 2. the outer fluid line 1 comprises a first outer fluid line part which which is an outer fluid line seal 3 is rotatably connected to a second outer fluid line part lb.

The outer fluid line seal 3 has been represented in a schematic manner only, and it is only important to note that this is an outer fluid line seal 3 or such a design that is an outer fluid line channel 4 (which is defined by the outer fluid line 1) is fully sealed with respect to the surrounding environment. It is noted that in this context the definition of fully sealed generally will and compass a situation in which the seal is not absolute, but fulfill the conditions required in the respective field to be indicated as such (generally an absolute seal which does not leak at all is impossible).

The first and second outer fluid line parts la, lb are part of a central swivel part 5 and each at an end opposite the end where they are connected by the outer fluid line seal 3 include a first connector or flange 6. The outer fluid line 1 further comprises two outer fluid line sections 7.8 at opposite sides of the central swivel part 5 each ending in a second connector or flange 9 which is intended to be connected to a corresponding first flange 6 (for example using bolts 10).

The inner fluid line 2 comprises a first inner fluid line part 2a which by an inner fluid line seal 11 is rotatably connected to a second inner fluid line part 2b. The first and second inner fluid line parts 2a, 2b are supported by respective ones of the outer fluid line sections 7.8 (in the illustrated embodiment they penetrate through and are connected for example welded to walls of the outer fluid line sections).

It is noted that the swivel arrangement may include more than one inner fluid line and a possible second inner fluid line 2. ' has been indicated in dotted lines.

The inner fluid line seal 11 (which in figure 1 has been illustrated in a schematic manner only and or which possible details will appear below) is constructed such that it does not fully seal but defines a gap which allows a certain amount of fluid communication between an inner fluid line 12 defined by the inner fluid line 2 and a surrounding fluid line channel, here the outer fluid line channel 4.

Referring to figures 2-6, details of some are illustrated which allow to realize such an inner fluid line seal 11 with a certain leak rate. The figures all show a region where the first and second inner fluid line parts 2a and 2b meet for defining the inner fluid line seal 11.

In the embodiment according to figure 2 the inner fluid line seal 11 is defined by a gap 13 between overlapping ends of the first and second inner fluid line parts 2a, 2b with different diameters (in this edition the end of the inner fluid line part 2b has a larger inner diameter than the outer diameter or the other inner fluid line part 2a). A variation of the dimension of the gap 3 (for example its width and / or length) results in a variation of the leak rate of the seal

11.

In the embodiment according to figure 3 a labyrinth seal (only indicated schematically) is provided at the gap 13, which also allows to influence the leak rate by creating a specific pressure drop over the seal 11.

In an alternative embodiment illustrated in Figure 4 a sliding ring 15 is positioned in the gap 13 between said overlapping ends of the first and second inner fluid line parts 2a, 2b. Such a sliding ring engages both overlapping ends for ensuring a concentric relative rotation between the inner fluid line parts 2a, 2b. Such a sliding ring 15 may also be combined with the labyrinth seal 14 (or other provisions not shown here).

In a very simple illustrated illustration in figure 5 the inner fluid line seal 11 is defined by a gap or channel 16 between frontal faces 17,18 or the first and second inner fluid line parts 2a, 2b, respectively. The dimension of the gap 16 (thus the distance between the frontal faces 17,18) is one of the factors determining the leak rate of the seal.

As illustrated in figure 6, the frontal faces 17,18 also may define ordered (or inclined), preferably parallel frontal faces. As a result the frontal faces 17,18 of the first and second inner fluid line parts 2a, 2b are separated by an inclined gap or channel 16. The inclination can be varied for increasing or reducing the length of the gap or channel 16, thus changing the leak rate or the seal 11.

The embodiment of the swivel arrangement illustrated in figures 7 and 8 looks much alike the edition in figure

1. However, an important difference is the position (here elevation) or the inner fluid line seal 11 which in an assembled position with substantial vertical orientation (figure 7) is now located at a level below the lower ones or corresponding first and second flanges 6.9 (in figure 1 the inner fluid line seal 11 is located at a level between the upper flange pair 6.9 and the lower flange pair 6.9).

When the swivel arrangement is disassembled (which generally means that the central swivel part 5 is disconnected and removed from sections 7 and 8), firstly the upper fluid line section 7 (after disconnecting the bolts 10) has to be lifted (arrow A in figure 8) that far that is the respective inner fluid line part 2a supported by it is completely moved above the upper pair or first and second flanges 6.9, where after (when also the lower first and second flanges 6.9 have been disconnected by removing the bolts 10) the central swivel part 5 can be removed sideways (arrow B) without being lifted.

In the embodiment according to figure 1 such a removal of the central swivel part 5 is more complicated. Not only should the upper outer fluid line section 7 be lifted as stated before, but also the lower outer fluid line section 8 should be lowered (or alternatively also the central swivel part 5 should be lifted, as generally will be the case because it generally is not simply possible to lower said lower section) until the respective inner fluid line part 2b supported by the lower section 8 is completely moved below the lower ones or corresponding first and second flanges 6.9 before the central swivel part 5 could be moved sideways . Due to the weight of the central swivel part 5 a lifting after preferably should be avoided and thus the embodiment according to figures 7 and 8 comes handy.

The invention is not limited to the described described before which may be varied widely within the scope of the invention as defined by the appending claims. Thus the swivel arrangement also may have other orientations apart from the vertical one illustrated, and as such terms upper, lower, below and similar terms then should be replaced by other terms, such as for example left and right.

Claims (12)

CONCLUSIONS A swivel arrangement comprising an outer fluid conduit concentrically surrounding at least one inner fluid conduit, the outer fluid conduit having a first outer fluid conduit portion rotatably connected to a second outer fluid conduit portion by an outer fluid conduit seal, each inner fluid conduit being provided of a first inner fluid conduit portion rotatably connected to a second inner fluid conduit portion through an inner fluid conduit seal and the outer fluid conduit defining an outer fluid conduit completely sealed to the environment by means of the outer fluid conduit seal, characterized in that each inner fluid conduit fluid conduit seal is constructed to define a gap that allows a certain amount of fluid communication between an inner fluid channel defined by the respective fluid conduit inner fluid conduit and an ambient fluid conduit channel defined by an ambient fluid conduit. The swivel device of claim 1, wherein the inner fluid conduit seal is constructed so as to allow passage of 0.01 to 10% of the fluid flow that passes through the inner fluid conduit. The swivel device of claim 2, wherein the inner fluid conduit seal is constructed to permit the passage of 0.1 to 2% of the fluid flow passing through the inner fluid conduit. A swivel arrangement as claimed in any preceding claim, wherein the inner fluid conduit seal is defined by a gap between overlapping ends of the first and second inner fluid conduit members with different diameters. The swivel feature of claim 4, wherein the overlapping ends of the first and second inner fluid conduit portions define a labyrinth seal. Swivel device according to claim 4 or 5, wherein a sliding ring is placed between said overlapping ends of the first and second inner fluid conduit parts. The swivel feature of any one of claims 1-3, wherein the inner fluid conduit seal is defined by a gap between frontal surfaces of the first and second inner fluid conduit members. A swivel arrangement according to claim 7, wherein the frontal planes define beveled, preferably parallel frontal planes. A swivel arrangement as claimed in any one of the preceding claims, having a central swivel portion comprising the first and second outer fluid conduit portions connected at one end by the outer fluid conduit seal and each having a first connector at an opposite end, and with two outer fluid conduit sections on opposite sides of the central swivel portion that each terminate in a second connector intended to be connected to a corresponding first connector, the outer fluid conduit sections carrying the inner fluid conduit portions and wherein in an assembled position of the swivel provision, in which the outer and inner fluid conduits extend substantially vertically, the inner fluid conduit seal is located at a level below the lower of corresponding first and second connectors. The swivel arrangement of claim 9, wherein the connectors include flanges intended to be bolted. 11. An assembly from a vessel provided with fluid lines mounted on the vessel and a swivel arrangement according to any one of the preceding claims, which is intended to rotatably connect the fluid lines mounted on the vessel to fluid lines moving relative to the vessel. 12. Assembly as claimed in claim 11, comprising a moonpool in the vessel, a rotating tower mounted in said moonpool for rotation relative to the vessel and carrying risers and a swivel provision mounted on the rotating tower for rotatably connecting the vessel mounted fluid lines with risers. ld