FLOATER BALLAST SYSTEM

Abstract

A floater includes a hull which has ballast tanks. Each ballast tank has a ballast water pipe and a vent pipe which are fluidly connected to the ballast tank. The ballast water pipes are interconnected to permit ballast water to be moved from each one of the ballast tanks to another one of the ballast tanks. The vent pipes are interconnected to permit gas to be moved from each one of the ballast tanks to another one of the ballast tanks. The ballast tanks, the ballast water pipes, and the vent pipes are fluidly interconnected to define a closed ballast volume.

Description

CROSS REFERENCE TO PRIOR APPLICATIONS

This application is a U.S. National Phase application under 35 U.S.C. § 371 of International Application No. PCT/NO2023/060112, filed on Dec. 5, 2023, and which claims benefit to Great Britain Patent Application No. 2218284.4, filed on Dec. 6, 2022. The International Application was published in English on Jun. 13, 2024 as WO 2024/123186 A1 under PCT Article 21(2).

FIELD

The present invention relates to a ballast system for a floater, for example, to a semi-submersible platform for electrical distribution equipment, and in particular to a system for managing ballast in such a floater.

BACKGROUND

Floaters, such as semisubmersible platforms or other types of vessels, are used for a variety of purposes in many industries, for example, within exploration of petroleum resources offshore, for generation of renewable energy, for aquaculture or fish farming, or for the distribution of electricity. With the increasing development of offshore renewable energy, one particularly relevant application is the use of floaters for carrying electrical distribution equipment, for example, for offshore wind farms. In such applications, subsea/sea floor cables may be routed to and from the floater, for example, so that a voltage step-up can be performed before electric energy is further distributed, e.g., to a shore-based grid via one or more export cable(s).

Floaters often have demanding design requirements in order to be able to operate safely and reliably in harsh offshore environments. It is generally desirable that floaters have a long design life and low maintenance requirements as their construction, design and installation can be very expensive and because accessibility for inspections, maintenance and repairs may be restricted. Taking a floater out of operation for inspection, maintenance or repairs (in situ or particularly if moving the floater to a yard e.g., for dry-docking) may involve considerable costs.

Floaters may in many cases need to be equipped with a ballast system which allows for the altering of the floater's ballast distribution. Such ballasting or de-ballasting may be necessary if the payload or displacement of the floater changes, if it is desirable to modify the trim of the platform, and/or if the weight distribution on the floater changes. An active control of ballast distribution can be used in some applications to counteract effects of environmental impacts.

There is a continuous need for further improved technology for offshore floaters.

SUMMARY

An aspect of the present invention is to provide further improved technology for offshore floaters, or at least to provide useful alternatives to existing technology.

In an embodiment, the present invention provides a floater. The floater includes a hull which comprises a plurality of ballast tanks. Each ballast tank of the plurality of ballast tanks comprises a ballast water pipe and a vent pipe which are fluidly connected to the ballast tank. The ballast water pipes are interconnected so as to permit ballast water to be moved from each one of the plurality of ballast tanks to another one of the plurality of ballast tanks. The vent pipes are interconnected so as to permit gas to be moved from each one of the plurality of ballast tanks to another one of the plurality of ballast tanks. The plurality of ballast tanks, the ballast water pipes, and the vent pipes are fluidly interconnected so as to define a closed ballast volume.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is described in greater detail below on the basis of embodiments and of the drawings in which:

FIG. 1 shows a first perspective views of a floater;

FIG. 2 shows a second perspective view of a floater;

FIG. 3 shows a schematic view of a cross-section of a floater hull; and

FIG. 4 schematically shows a ballast tank with a ballast water and vent gas distribution arrangement.

DETAILED DESCRIPTION

In an embodiment, the present invention provides a floater comprising a hull having a plurality of ballast tanks, each ballast tank having a ballast water pipe and a vent pipe fluidly connected thereto, wherein the ballast water pipes are interconnected so as to permit ballast water to be moved from each one of the plurality of ballast tanks to another one of the plurality of ballast tanks, and wherein the vent pipes are interconnected so as to permit gas to be moved from each one of the plurality of ballast tanks to another one of the plurality of ballast tanks, and wherein the ballast tanks, ballast water pipes, and vent pipes are fluidly interconnected and define a closed ballast volume.

The floater may be provided for carrying electrical distribution equipment.

Each vent pipe may be fluidly connected to a common vent equalization pipe.

At least a part of the common vent equalization pipe may extend horizontally above the hull.

Each ballast water pipe may be fluidly connected to a common ballast distribution pipe.

At least a part of the common ballast distribution pipe may extend horizontally above the hull.

The floater may further comprise a plurality of pumps, each pump being arranged in the hull and being fluidly connected to a respective ballast tank. The pump may in this case be arranged in a respective ballast tank.

At least one or each ballast water pipe may comprise a ballast pipe valve which is operable to isolate the respective ballast tank from the other ballast pipe(s).

At least one or each ballast water pipe may comprise a ballast pipe valve which is operable to isolate the respective ballast tank from the common ballast distribution pipe.

The ballast pipe valve(s) may be located at an upper part of the hull, for example, at an upper half of the hull or at an upper 20% section of the hull. The ballast pipe valves may alternatively be located above a design waterline of the hull or above the hull.

At least one or each vent pipe may comprise a vent pipe valve which is operable to isolate the respective ballast tank from the other vent pipe(s).

At least one or each vent pipe may comprise a vent pipe valve which is operable to isolate the respective ballast tank from the common vent equalization pipe.

The vent pipe valve(s) may be located at an upper part of the hull, for example, at an upper half of the hull, or at an upper 20% section of the hull. The vent pipe valves may alternatively be are located above a design waterline of the hull or above the hull.

The common vent equalization pipe and/or the common ballast distribution pipe may be located at an upper part of the hull, for example, at an upper half of the hull, or at an upper 20% section of the hull. The common vent equalization pipe and/or the common ballast distribution pipe may alternatively be located above a design waterline of the hull or above the hull.

The hull may be a semi-submersible hull and comprise a plurality of vertical or substantially vertical columns.

Each ballast water pipe may be arranged vertically inside a column.

Each vent pipe may be arranged vertically inside a column.

The above and other characteristics will become clear from the following description of illustrative, non-restrictive examples, with reference to the attached drawings.

FIGS. 1 and 2 illustrate a floater 100 having a hull 101. In this example, the hull 101 is a semi-submersible hull having four columns 102a-d and a pontoon structure 103 arranged below a design waterline 104 for the hull 101. The hull 101 may alternatively have fewer or more than four columns, for example, three columns. The pontoon structure 103 may be a single pontoon structure, or may be made up of individual pontoon structure sections which are arranged between all or some of the columns 102a-d. Some or all of the columns 102a-d may optionally be interconnected by another type of structure than a pontoon, such as beams or trusses. The floater 100 is configured to carry a deck (not shown in the drawings) on the columns 102a-d, with the deck having electrical distribution equipment arranged thereon, such as switchgear, shunt reactors, transformers, and other equipment which can, for example, be connected to an offshore wind farm to receive and redistribute electric power therefrom.

The hull 101 comprises a plurality of ballast tanks arranged therein. The ballast tanks can be arranged in the columns 102a-d, in the pontoon structure 103, or in both the columns 102a-d and in the pontoon structure 103. The hull 101 may, for example, have a number of permanent ballast tanks which are filled (typically with water) upon construction, and then closed and sealed. The hull 101 may also have a fixed ballast arranged therein.

Such a permanent and fixed ballast may account for the majority of ballast used in the hull 101.

The hull 101 may also have ballast tanks in which the level of ballast water can be varied during operation. The hull 101 as illustrated in FIGS. 1 and 2 may, for example, have four such variable ballast tanks arranged in the hull 101, e.g., one ballast tank below or in each column 102a-d, or one ballast tank in the pontoon structure 103 between each pair of columns 102a-d. Such variable ballast tanks may be used to modify the ballast distribution of the hull 101 during operation.

FIG. 3 illustrates an example in which the hull 101 has two ballast tanks 10 a, b arranged below two columns. Each of the ballast tanks 10a, b has a ballast water pipe 11a, b and a vent (i.e., ventilation) pipe 12a, b fluidly connected thereto. Ballast water can be added into or removed from the tank 10a, b via the ballast water pipe 11a, b. The vent pipes 12a, b allow gas (e.g., air or an inert gas such as nitrogen forming the tank atmosphere) to be removed from or added into the ballast tank 10a, b in accordance with the removal or addition of ballast water from or into the tank 10a, b.

The ballast water pipes 11a, b are interconnected so as to permit ballast water to be moved from one of the ballast tanks 10a, b to the other tank 10a, b. As the two tanks 10a, b are arranged at different locations in the hull 101, a redistribution of ballast water between the tanks can be used to influence the ballast distribution, for example, to manipulate the trim of the floater 100.

Although only two tanks 10a, b are illustrated in FIG. 3, the skilled reader will understand that the floater 100 may be designed with three, four or more of such tanks and associated pipe systems.

The vent pipes 12a, b are interconnected so as to permit gas to be moved from one of the ballast tanks 10a, b to the other tank 10a, b as ballast water is moved in the opposite direction.

The ballast tanks 10a, b, ballast water pipes 11a, b, and vent pipes 12a, b are fluidly interconnected and define a closed interior volume for ballast. This closed interior volume, formed by the interior volumes of the ballast tanks 10a, b, ballast water pipes 11a, b, and vent pipes 12a, b, has no fluid connection or opening to the ambient during operation of the floater 100. The ballast water and gas (e.g., air or an inert gas such as nitrogen) can be provided into the tanks 10a, b during construction of the hull 101, and the interior volume can thereafter be closed and sealed from the ambient.

The fluid contained in the interior volume (i.e., ballast water and gas) thereby remains unchanged during operation. No new water or air is in particular provided into the interior volume, i.e., into the tanks 10a, b or associated pipes. This prevents corrosion of the interior of the tanks 10a, b and associated pipes in that no fresh oxygen is permitted to enter the volume.

In a floater 100 as illustrated in FIGS. 1 and 2, four ballast tanks 10a-d may be provided, and each of the ballast water pipes 11a-d may be interconnected via a common ballast distribution pipe 14. This is illustrated in FIG. 4. Each vent pipe 12a-d can similarly be fluidly connected to a common vent equalization pipe 13. The common vent equalization pipe 13 and the common ballast distribution pipe 14 may, for example, be arranged as ring pipes extending around the hull 101. The common vent equitization pipe 13 and the common ballast distribution pipe 14 are advantageously arranged above the hull 101, for example, on or integrated in a deck structure of the floater 100 which is supported on the top of the columns 102a-d (the deck is not illustrated in FIGS. 1 and 2). Ballast water can thereby be selectively redistributed between desired tanks according to operational requirements.

In a floater 100 as illustrated in FIGS. 1 and 2, pairs of ballast tanks 10a-d may alternatively be interconnected, e.g., a ballast tank located below column 102a may be interconnected with a diagonally opposite ballast tank located below column 102c, and similarly for ballast tanks located below columns 102b and 102d.

FIG. 3 shows that pumps 15a, b may be provided to pump ballast water between the tanks 10a-d. The pumps 15a, b may be arranged in the hull 101 and fluidly connected to a respective tank 10a-d. The pumps 15a, b are advantageously arranged in a respective ballast tank 10a-d. The pumps 15a, b can optionally be fluidly connected to the respective tank 10a-d via piping.

One or more of the ballast water pipes 11a-d may comprise a ballast pipe valve 16a, b (see FIG. 3) which is operable to isolate the respective ballast tank 10a-d from the other ballast water pipe(s) 11a-d and/or from the common ballast distribution pipe 14.

One or more of the vent pipes 12a-d may alternatively or additionally comprise a vent pipe valve 17a, b (see FIG. 3) which is operable to isolate the respective ballast tank 10a-d from the other vent pipe(s) 12a-d and/or from the common vent equalization pipe 13.

The ballast pipe valve(s) 16a, b and/or the vent pipe valve(s) 17a, b is/are advantageously located at an upper part of the hull 101, for example, at an upper half of the hull 101, at an uppermost 20% of the height of the hull 101, and/or above a design waterline 104 (see FIG. 2) of the hull 101. The ballast pipe valve(s) 16 a, b and/or the vent pipe valve(s) 17a, b may alternatively be arranged above the hull 101, for example, on a deck or integrated in a deck structure of the floater 100.

Similarly, the common vent equalization pipe 13 and/or the common ballast distribution pipe 14 can advantageously be located at an upper part of the hull 101, for example, at an upper half of the hull 101, at an uppermost 20% of the height of the hull 101, and/or above a design waterline 104 of the hull 101. The common vent equalization pipe 13 and/or the common ballast distribution pipe 14 may alternatively be arranged above the hull 101, for example, on a deck or integrated in a deck structure of the floater 100.

Such arrangement of the ballast pipe valves 16a, b and the vent pipe valves 17a, b and/or the common vent equalization pipe 13 and the common ballast distribution pipe 14 can provide easier accessibility, for example, for operation of the valves or for inspections or maintenance.

In some examples, the hull 101 is a semi-submersible hull and comprises a plurality of vertical or substantially vertical columns 102a-d. The hull 101 may, for example, be a four-column hull as illustrated in FIG. 1 or 2. Each ballast water pipe 11a-d and each vent pipe 12a-d are advantageously arranged vertically inside a column 102a-d. The ballast pipe valves 16a, b and the vent pipe valves 17a, b may in such an arrangement be placed at or adjacent the top of each column 102a-d.

The floater 100 may be fitted with appropriate sensor equipment, for example, tank gauges/level sensors in the tanks 10a-d in order to read the current ballast water levels; flow meters, discharge pressure gauges or power consumption sensors on pumps 15a, b to monitor ballast water flow rates; oxygen sensors in the interior volume in order to provide that a low-oxygen atmosphere is maintained in the interior volume, etc. Improved knowledge of the condition of the hull 101 can be obtained by providing such sensor equipment and inspection requirements may be relaxed. For example, if consistently low oxygen levels in the interior volume are documented over time, one may have sufficient confidence that no significant corrosion has occurred so as to optimize, obviate, or possibly delay the need for physical inspection.

According to examples described here, a redistribution of ballast water, for example, for floater trim adjustments, is possible with a lower risk that such operations provides fresh oxygen into interior volumes of the tanks or associated piping, which can lead to corrosion. A longer floater lifetime and reduced inspection requirements can thus be obtained via the examples described herein. This may allow the floater 100 to operate for longer periods without inspection or with relaxed inspection requirements.

Although the disclosed examples and embodiments relate to a floater for carrying electrical distribution equipment, the teaching of the present disclosure and any embodiment described or claimed herein are not limited to such application and may be equally well employed for a floater for any purpose.

The present invention is not limited by the embodiments described above; reference should be had to the appended claims.

LIST OF REFERENCE NUMERALS

• • 10a Ballast tank
  • 10b Ballast tank
  • 10c Ballast tank
  • 10d Ballast tank
  • 11a Ballast water pipe
  • 11b Ballast water pipe
  • 11c Ballast water pipe
  • 11d Ballast water pipe
  • 12a Vent pipe
  • 12b Vent pipe
  • 12c Vent pipe
  • 12d Vent pipe
  • 13 Common vent equalization pipe
  • 14 Common ballast distribution pipe
  • 15a Pump
  • 15b Pump
  • 16a Ballast pipe valve
  • 16b Ballast pipe valve
  • 17a Vent pipe valve
  • 17b Vent pipe valve
  • 100 Floater
  • 101 Hull
  • 102a Column
  • 102b Column
  • 102c Column
  • 102d Column
  • 103 Pontoon structure
  • 104 Design waterline

Claims

1-16. (canceled)

17. A floater comprising:

a hull comprising a plurality of ballast tanks, each ballast tank of the plurality of ballast tanks comprising a ballast water pipe and a vent pipe which are fluidly connected to the ballast tank,

wherein,

the ballast water pipes are interconnected so as to permit ballast water to be moved from each one of the plurality of ballast tanks to another one of the plurality of ballast tanks,

the vent pipes are interconnected so as to permit gas to be moved from each one of the plurality of ballast tanks to another one of the plurality of ballast tanks, and

the plurality of ballast tanks, the ballast water pipes, and the vent pipes are fluidly interconnected so as to define a closed ballast volume.

18. The floater as recited in claim 17, wherein each of the vent pipes is fluidly connected to a common vent equalization pipe.

19. The floater as recited in claim 18, wherein at least one or each vent pipe comprises a vent pipe valve which is configured to isolate a respective one of the plurality of ballast tanks from the common vent equalization pipe.

20. The floater as recited in claim 18, wherein at least a part of the common vent equalization pipe is arranged to extend horizontally above the hull.

21. The floater as recited in claim 18, wherein each of the ballast water pipes is fluidly connected to a common ballast distribution pipe.

22. The floater as recited in claim 21, wherein at least a part of the common ballast distribution pipe is arranged to extend horizontally above the hull.

23. The floater as recited in claim 21, wherein, the common vent equalization pipe and/or the common ballast distribution pipe is/are arranged at an upper part of the hull, or the common vent equalization pipe and/or the common ballast distribution pipe is/are located above a design waterline of the hull or above the hull.

24. The floater as recited in claim 21, wherein at least one or each ballast water pipe comprises a ballast pipe valve which is configured to isolate a respective one ballast tank of the plurality of ballast tanks from the common ballast distribution pipe.

25. The floater as recited in claim 24, wherein, the ballast pipe valve(s) is/are arranged at an upper part of the hull, or the ballast pipe valves are located above a design waterline of the hull or above the hull.

26. The floater as recited in claim 17, further comprising:

a plurality of pumps,

wherein,

each pump of the plurality of pumps is arranged in the hull, and

one respective pump of the plurality of pumps is fluidly connected to one respective ballast tank of the plurality of ballast tanks.

27. The floater as recited in claim 17, wherein at least one or each ballast water pipe comprises a ballast pipe valve which is configured to isolate a respective one ballast tank of the plurality of ballast tanks from the other ballast water pipe(s).

28. The floater as recited in claim 27, wherein,

the ballast pipe valve(s) is/are arranged at an upper part of the hull, or

the ballast pipe valves are arranged above a design waterline of the hull or above the hull.

29. The floater as recited in claim 17, wherein at least one or each vent pipe comprises a vent pipe valve which is configured to isolate a respective one ballast tank of the plurality of ballast tanks from the other vent pipe(s).

30. The floater as recited in claim 29, wherein,

the vent pipe valve(s) is/are arranged at an upper part of the hull, or

the vent pipe valves are arranged above a design waterline of the hull or above the hull.

31. The floater as recited in claim 17, wherein the hull is a semi-submersible hull and comprises a plurality of vertical or substantially vertical columns.

32. The floater as recited in claim 31, wherein a respective one ballast water pipe of the ballast water pipes is arranged vertically inside a respective one of the plurality of vertical or substantially vertical columns.

33. The floater as recited in claim 31, wherein a respective one vent pipe of the vent pipes is arranged vertically inside a respective one of the plurality of vertical or substantially vertical columns.