NO346813B1

NO346813B1 - Floating aquaculture system with means for elevating structures of the aquaculture system

Info

Publication number: NO346813B1
Application number: NO20220265A
Authority: NO
Inventors: Alf Reidar Sandstad
Original assignee: Seafarming Systems As
Priority date: 2021-03-02
Filing date: 2022-03-02
Publication date: 2023-01-16
Also published as: NO20220265A1; EP4301130A1; AU2022229065A1; AU2022229065B2; CA3209447A1; CL2023002572A1; WO2022186700A1

Description

FLOATING AQUACULTURE SYSTEM WITH MEANS FOR ELEVATING STRUCTURES OF THE AQUACULTURE SYSTEM

This invention concerns a floating aquaculture system. The aquaculture system is adapted for raising aquatic animals such as fish and crustaceans. The aquaculture system comprises a plurality of receptacles for raising the aquatic animals, and the receptacles are formed in a rigid material. The wall and bottom are watertight and provided with necessary openings for inlet of water and outlet of water to obtain a water circulation necessary for raising the aquatic animals. The aquaculture system is further provided with a pump system for filling empty receptacles and for emptying the receptacles. More particularly the invention concerns a central unit to which each receptacle is connected. Even more particularly the central unit is made of a rigid material and self-supported. Even more particularly each receptacle is locked in the vertical direction relative to the central unit. Each receptacle can be unlocked from the central unit and locked again to the central unit in another vertical position, depending on the floating draft of the receptacle. The invention also concerns a method of utilizing the buoyancy of the receptacles to lift the central unit above the water surface, and to lift the central unit together with receptacles above the water surface.

A common fish farming operation at sea comprises a number of fish pens and a feed barge. The fish pen comprises a floating member that encircles an enclosure. The enclosure is formed by a net. The feed barge is formed in concrete or steel and houses feed storage, feeding systems, a control unit etc. Due to fouling the nets are replaced at intervals with clean nets. After a completed production cycle where the fish have been harvested, the nets are removed, and the floating members are cleaned in situ by subsequently lifting parts of the floating members above a water surface and clean them by pressurized water. The feed barge cannot be cleaned in situ and are towed to a dock.

Fish pens with a closed enclosure are alternatives to the open net pens. The enclosure is formed by a watertight material. The watertight material may be a flexible material, such as a tarpaulin or a synthetic material. The watertight material may be a solid material, such as steel or concrete, or a sandwich of synthetic materials. Enclosures of watertight material need cleaning from fouling as well. In addition, it is beneficial to disinfect the surfaces to reduce risk of diseases.

Document NO 310801 B1 describes a floating structure adapted to be a quay for a plurality of floating trays for farming of fish. The floating trays are positioned and made fast between jetties. Document NO 344177 B1 describes a floating frame construction which comprises a plurality of floating trays for farming of fish. Each tray is provided with adjustable buoyancy members. Each tray may be elevated relative to the frame by emptying the buoyancy members. Document NO 344466 B1 describes a fish cage comprising a buoyant body for floating in a body of water. The fish cage comprises lifting means arranged between the buoyant body and the cage. The lifting means are configured for moving the cage between a level of the buoyant body and a position in which at least a portion of the cage is above the buoyant body. Document NO 343353 B1 describes an elongated floating structure comprising a plurality of floating trays for farming of fish. The trays are provided with buoyancy means and are positioned between outriggers.

It is known that free floating cages made of a rigid material suffer from the phenomena of sloshing within the cage. The invention has for its object to remedy or to reduce at least one of the drawbacks of the prior art, or at least provide a useful alternative to prior art.

The object is achieved through features, which are specified in the description below and in the claims that follow.

The invention concerns a floating aquaculture system comprising fish pens where the enclosure is formed in a stiff material. The fish pens are fastened to a central unit in such a way that the fish pen and the central unit make a rigid body with limited wave motions compared to what would be the case if each of the units where free floating. The limited wave motions of the system will thereby limit sloshing within the cages.

The invention further concerns a floating aquaculture system where each of the fish pens can be lifted completely above a water surface by utilizing the buoyancy of other fish pens in the system and without any assistance from an internal crane arrangement or an external lifting vessel. By using the same methodology, the central unit may be lifted completely above the water surface. Thus, all components of the aquaculture system can be elevated above the water surface in situ. All surfaces, including external surfaces, of the aquaculture system are available for cleaning and disinfection.

The invention is defined by the independent patent claims. The dependent claims define advantageous embodiments of the invention.

In a first aspect the invention relates more particularly to an aquaculture system for raising aquatic organisms, the aquaculture system comprising a plurality of rigid receptacles and a rigid central unit provided with a plurality of arms, each receptacle comprises a watertight rigid wall and a watertight rigid bottom. In more detail:

- each receptacle is connected to a first arm and a second arm at opposite sides of the receptacle by a first guiding mechanism and a second guiding mechanism;

- the first guiding mechanism and the second guiding mechanism are each provided with a locking mechanism adapted to optionally lock each receptacle at optionally several vertical positions, including at least at a maximum depth of operation and at a maximum floating level of operation of the receptacle, and

- the central unit (3) is adapted to be lifted by a plurality of receptacles (2) locked to the central unit (3) at an optionally vertical position.

The central unit may be formed by a rigid material such as steel or concrete. The central unit may be formed with necessary internal cavities to be a floating body. Some of the cavities may be filled with a buoyancy material.

The central unit may be formed by a combination of rigid materials. The central unit may be sufficiently stiff to be self-supported. The central unit may form a central longitudinal axis. The central unit may be formed with a plurality of arms. The arms extend outwardly relatively to the central axis. Preferably the arms are arranged pairwise to each side such that the central unit is laterally symmetrical about the central axis. A recess may be formed between two neighbouring arms. In operation the receptacle is positioned within the recess.

Each receptacle may be connected to the central unit with a third guiding mechanism positioned between the first guiding mechanism and the second guiding mechanism, and the third guiding mechanism may be provided with the locking mechanism adapted to lock each receptacle at optionally several vertical positions, including at the maximum depth of operation and at the maximum floating level of operation of the receptacle.

The receptacle may be locked to the central unit at the maximum depth of operation of the receptacle.

Each receptacle may be locked to the central unit in the horizontal direction by the first guiding mechanism and by the second guiding mechanism. Each receptacle may be locked to the central unit in the horizontal direction by the first guiding mechanism, by the second guiding mechanism, and by the third guiding mechanism.

The aquaculture system may be provided with at least one first pump system adapted for pumping water into each receptacle.

The aquaculture system may be provided with at least one second pump system adapted for pumping water out of each receptacle.

Each receptacle may be provided with a fixed external buoyancy body. The external buoyancy body may comprise a plurality of hollow columns. The hollow column may comprise a fixed ballast. The hollow column may comprise a variable ballast such as water. The advantage with a plurality of hollow columns is that the columns may be spaced at regular intervals around a periphery of the receptacle, and that the columns provide stability at any floating draft of the receptacle. Thereby, the receptacle is stable as a unit of its own and cannot tilt. The advantage is also that the receptacle cannot sink if the receptacle is punctured. In operation there is a slight hydrodynamic overpressure inside the receptacle compared to the outside. This is due to that water is pumped into the receptacle to provide the aquatic organisms with oxygen rich water, and the outlet(s) are arranged to maintain steady state. i.e., inflow of water is equal to outflow of water, when the water surface inside the receptacle is slightly above the water surface outside the receptacle, e.g. 10 mm height difference. This is the operational draft of the receptacle, and the external buoyancy body secures the receptacle at the operational draft. If the receptacle is punctured by an accident during operation, the hydrodynamic overpressure within the receptacle vanish and the receptacle will ascend in the water column and reach an equilibrium draft due to the external buoyancy body.

At least one of the first guiding mechanism, the second guiding mechanism, and the third guiding mechanism may be connected to a hollow column. In an alternative embodiment, the first guiding mechanism, the second guiding mechanism, and the third guiding mechanism may be connected to the receptacle between the hollow columns.

In a second aspect the invention relates more particularly to a method for adjusting a vertical position of at least one first receptacle in an aquaculture system relative to a water surface. The method comprises the steps of:

a) providing an aquaculture system as described above;

b) fill a plurality of receptacles with water until the receptacles reach an intended depth of operation;

c) activate a plurality of locking mechanisms such that the plurality of the receptacles are locked in a vertical direction relative to the central unit; and

d) pump water out of the plurality of receptacles until the receptacles have ascended to a desired level in the water column, and thereby the complete central unit is lifted above the water surface.

The method may comprise that step c) of the method comprises to lock all the receptacles (2) to the central unit (3) when the receptacles (2) are at the intended depth of operation. The intended depth of operation may be the maximum depth of operation of the receptacles.

The method may comprise to prior to step d):

- unlock the at least one receptacle from the central unit prior to pumping water out of the at least one receptacle; and

- lock the at least one receptacle (2) to the central unit (3) at a desired vertical position after pumping out water.

The method may comprise to lock the at least one receptacle to the central unit at a maximum floating level of operation.

The method may further comprise to:

- pump water out of the remaining receptacles such that the remaining receptacles ascend in the water column, and thereby the complete central unit and the at least one receptacle are lifted above the water surface.

In the following is described an example of a preferred embodiment illustrated in the accompanying drawings, wherein:

Figs. 1A-D show schematically six receptacles and a central unit according to the invention where all receptacles are dived to a maximum depth of operation;

Figs. 2A-C show the same as figures 1A-D in an alternative embodiment where all receptacles are emptied for water and floating on a water surface;

Figs. 3A-D show the same as figures 1A-D in an alternative embodiment where one receptacle is emptied for water and floating on the water surface;

Figs. 4A-D show the same as figures 1A-D in an alternative embodiment where two receptacles are emptied for water and floating on the water surface;

Figs. 5A-E show the same as figures 4A-D in an alternative embodiment where two receptacles are emptied for water, the remaining receptacles are partly emptied for water, and the empty receptacles and the central unit are lifted above the water surface;

Figs. 6A-D show the same as figures 1A-D in an alternative embodiment where two receptacles in the middle are emptied for water and floating on the water surface;

Figs. 7A-D show the same as figures 6A-D in an alternative embodiment where two receptacles in the middle are emptied for water, the remaining receptacles are partly emptied for water, and the empty receptacles and the central unit are lifted above the water surface;

Figs. 8A-D show the same as figures 1A-D in an alternative embodiment where all receptacles are partly emptied for water and the central unit is lifted above the water surface.

In the drawings, the reference numeral 1 indicates an aquaculture system for raising aquatic organisms. The aquaculture system 1 comprises a plurality of rigid receptacles 2 and a rigid central unit 3.

Each receptacle 2 may be formed in steel, concrete or other rigid synthetic material such as a polymer material or a metal. The receptacle 2 comprises a watertight wall 21 and a watertight bottom 23. The wall 21 may be provided with one or more closable through openings (not shown) for pumping water into the receptacle 2 and/or for pumping water out of the receptacle 2. The bottom 23 may be provided with one or more closable through openings (not shown) for pumping water into the receptacle 2 and/or for pumping water out of the receptacle 2. The receptacle 2 is provided with an external buoyancy body 7. The external buoyancy body is fixed to the wall 21. The external buoyancy body 7 may be a hollow column 71 and the receptacle 2 may be provided with a plurality of hollow columns 71. The plurality of hollow columns 71 are evenly spaced around the circumference of the receptacle 2. Each receptacle 2 is shown with four hollow columns 71 in the figures. The hollow columns 71 are distributed with a radial distance of 90°. The hollow columns 71 extend from the upper portion of the receptacle 2 to the lower portion of the receptacle 2.

The receptacle 2 will float as a separate unit on water. The external buoyancy body 7 provides stability such that the receptacle will not tilt when it is empty of water, partly filled with water or completely filled with water. The external buoyancy body 7 will keep the receptacle floating even if the wall 21 and/or the bottom 23 are accidently punctured.

The receptacle 2 may be assembled at an appropriate location and thereafter towed to the central unit 3. At the central unit 3 the receptacle 2 is connected to the central unit 3 by connecting the receptacle 2 to the guiding mechanism 4. The receptacle 2 is slidably connected to a first guiding mechanism 41 and to a second guiding mechanism 42 and optionally to a third guiding mechanism 43. The guiding mechanisms 41, 42, 43 are preferably oriented vertically. The guiding mechanisms 41, 42, 43 may be identical. The guiding mechanisms 41, 42, 43 may be of a rack and pinion type (not shown). The guiding mechanisms 41, 42, 43 may be of a skid type (not shown). A locking mechanism 5 fixes the vertical position of the receptacle 2 relative to the vertical position of the central unit 3. The locking mechanism 5 may be a bolt.

The central unit 3 is formed by a rigid material such as steel or concrete. The central unit 3 may be formed by a combination of rigid materials. The central unit 3 is sufficiently stiff to be self-supported. The central unit 3 forms a central longitudinal axis 39. The central unit 3 is formed with a plurality of arms 31. The arms 31 extend outwardly relatively to the central axis 39. Preferably the arms 31 are arranged pairwise to each side such that the central unit 3 is laterally symmetrical about the central axis 39. A recess 33 is formed between two neighbouring arms 31. In operation the receptacle 2 is positioned within the recess 33. The central unit 3 is formed as a floating body with a bottom 35 and a deck 37.

In one embodiment the guiding mechanisms 4, 41, 42, 43, are positioned on the external surface of the hollow columns 71.

The central unit 3 is provided with a water handling system 6. The water handling system 6 may comprise a first pump system 61 which is adapted to pump water into each of the receptacles 2. The pump system 6 may comprise a second pump system 62 which is adapted to pump water out of each of the receptacles 2. In one embodiment the first pump system 61 comprises a first pump 60 which is displaceable within an internal service channel 63 in the hollow column 71. In operation the service channel 63 forms part of water channel 64 which in the figures are shown with two openings 65 in the wall 21. The bottom 23 is provided with a bottom outlet 66. The bottom 23 may in addition be provided with a number of hatchways 67. The outlet 66 may form part of the second pump system 62. The second pump system 62 may comprise a second pump (not shown) in fluid connection with the outlet 66 via a tube (not shown). The first pump system 61 and the second pump system 62 may be fully integrated in the receptacles 2. The first pump system 61 and the second pump system 62 may comprise of parts located on the central unit 3 and parts located in the receptacles 2.

The central unit 3 may be provided with equipment (not shown) necessary for operating a floating aquaculture system 1. Such equipment may be a power generator, a feed storage, a feeding equipment, a control system, a building comprising a control unit and a living room, and more. Some of the equipment may be positioned on the deck 37.

Figures 1A-D show the aquaculture system 1 in ordinary operation. All receptacles 2 are filled with water and the receptacles 2 are dived to a maximum depth of operation. The receptacles 2 are fixed to the central unit 3 at the three guiding mechanisms 41, 42, 43. The receptacles and the central unit 2 is together a stiff unit. The receptacles 2 contain the aquatic organisms (not shown) that are raised in the aquaculture system 1. Water quality in the closed receptacles 2 are maintained by the pump system 6.

Figures 2A-D show the aquaculture system 1 when all the receptacles 2 have been emptied for water. This is achieved by operating the locking mechanism 5 such that the receptacles 2 are unlocked. The receptacles 2 will ascend in a water column 91 along the guiding mechanisms 41, 42, 43 when water is pumped out of the receptacles 2. The locking mechanism 5 is operated when the receptacles 2 have reached their maximum floating level, and the receptacles 2 are then fixed to the central unit 3 at this level. In this position the receptacles 2 may be cleaned and disinfected. The receptacles 2 are kept in this position when there is no need to stock aquatic animals in the receptacle 2. The aquaculture system 1 may be towed to a new location when all the receptacles 2 are in the upper position. The central unit 3 is moored to a mooring system (not shown). The central unit 3 is disconnected from the mooring system prior to towing. The central unit 3 is connected to a new mooring system after arrival to a new location.

If needed, a receptacle 2 may be disconnected from the central unit 3 and towed to a suitable location for repair.

Figures 3A-D show that one receptacle is positioned at the maximum floating level. This is achieved by unlocking one receptacle 2 and pumping water out of this receptacle 2, while the other receptacles 2 remain in their ordinary operational mode. Water is pumped out of the unlocked receptacle 2, and the receptacle 2 will ascend in the water column 91. The volume of water within the receptacle 2 will diminish and the aquatic animals within the receptacle will be crowded. Thereby it is possible to harvest the aquatic animals by pumping.

Figures 4A-D and figures 5A-D show an operation where two receptacles 2 and the central unit 3 are lifted above a water surface 9. Figures 4A-D show the preparation step. Two receptacles 2 positioned diagonally relative to the longitudinal axis 39 are emptied for water and locked to the central unit 3 at their maximum floating level as shown in figures 4A, 4C, 4D. Thereafter water is pumped out of the remaining receptacles 2 which are locked to the central unit 3 at their maximum depth of operation. Water is pumped out at the same speed from the remaining receptacles 2. The upward buoyancy force of remaining receptacles 2 will increase as water is pumped out the receptacles 2. The remaining receptacles 2 carry between them the load of the central unit 3 and the two empty receptacles 2. Pumping of water is stopped when the central unit 3 is lifted to an intended level above the water surface 9 as shown in figures 5A, 5C-E. The bottom 23 of the empty receptacles 2 are above water level and it is possible to clean and disinfect the bottom 23 in this position. Thereby it is possible to maintain the whole receptacle 2 at the inside and at the outside at site without bringing the receptacle 2 to a dry dock. It is not necessary to use expensive lifting equipment such as a lifting vessel.

The central unit 3 and the two empty receptacles 2 are lowered by pumping water into the remaining receptacles 2.

Figures 6A-D and figures 7A-D show an alternative operation where two receptacles 2 in the middle of the central unit 3 and the central unit 3 are lifted above a water surface 9. Figures 6A-D show the preparation step. Two receptacles 2 positioned at each side to the longitudinal axis 39 are emptied for water and locked to the central unit 3 at their maximum floating level as shown in figures 6A, 6C, 6D. The procedure is similar to the procedure described above where two diagonally positioned receptacles 2 are lifted.

Figures 8A-D show an alternative operation. All receptacles 2 are kept locked to the central unit 3. Water is pumped out of the receptacles 2. The receptacles 2 will ascend in the water column 91 and carry between them the load of the central unit 3. Pumping of water is stopped when the central unit 3 is lifted to an intended level above the water surface 9. The bottom 35 of the central unit 3 is above water level and it is possible to clean and disinfect the bottom 35 in this position.

Use of the verb "comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

C l a i m s

1. An aquaculture system (1) for raising aquatic organisms, the aquaculture system (1) comprising a plurality of rigid receptacles (2) and a rigid central unit (3) provided with a plurality of arms (31), each receptacle (2) comprises a watertight rigid wall (21) and a watertight rigid bottom (23) and each receptacle (2) is vertically adjustable to the central unit (3), c h a r a c t e r i s e d i n that - each receptacle (2) is connected to a first arm (31) and a second arm (31) at opposite sides of the receptacle (2) by a first guiding mechanism (4, 41) and a second guiding mechanism (4, 42);

- the first guiding mechanism (4, 41) and the second guiding mechanism (4, 42) are each provided with a locking mechanism (5) adapted to optionally lock each receptacle (2) at optionally several vertical positions, including at least at a maximum depth of operation and at a maximum floating level of operation of the receptacle (2), and

2. The aquaculture system (1) according to claim 1, wherein each receptacle (2) is connected to the central unit (3) with a third guiding mechanism (4, 43) positioned between the first guiding mechanism (4, 41) and the second guiding mechanism (4, 42), and the third guiding mechanism (4, 43) is provided with the locking mechanism (5) adapted to lock each receptacle (2) at optionally several vertical positions, including at the maximum depth of operation and at the maximum floating level of operation of the receptacle (2).

3. The aquaculture system (1) according to any one of the preceding claims, wherein the receptacle (2) is locked to the central unit (3) at the maximum depth of operation of the receptacle (2).

4. The aquaculture system (1) according to any one of the preceding claims, wherein the aquaculture system (1) is provided with at least one first pump system (61) adapted for pumping water into each receptacle (2).

5. The aquaculture system (1) according to any one of the preceding claims, wherein the aquaculture system (1) is provided with at least one second pump system (62) adapted for pumping water out of each receptacle (2).

6. The aquaculture system (1) according to any one of the preceding claims, wherein each receptacle (2) is provided with a fixed external buoyancy body (7).

7. The aquaculture system (1) according to claim 6, wherein the external buoyancy body (7) comprises a plurality of hollow columns (71).

8. The aquaculture system (1) according to claim 7, wherein the hollow column (71) comprises a fixed ballast.

9. The aquaculture system (1) according to claim 7, wherein at least one of the first guiding mechanism (4, 41), the second guiding mechanism (4, 42), and the third guiding mechanism (4, 43) is connected to the hollow column (71).

10. Method for adjusting a vertical position of a central unit (3) in an aquaculture system (1) relative to a water surface (9), c h a r a c t e r i s e d i n that the method comprises the steps of:

a) providing an aquaculture system (1) according to any one of claims 1 to 9; b) fill a plurality of receptacles (2) with water until the receptacles (2) reach an intended depth of operation;

c) activate a plurality of locking mechanisms (5) such that the plurality of the receptacles (2) are locked in a vertical direction relative to the central unit (3); and d) pump water out of the plurality of receptacles (2) until the receptacles (2) have ascended to a desired level in the water column (91), and thereby the complete central unit (3) is lifted above the water surface (9).

11. The method according to claim 10, wherein step c) of the method comprises to lock all the receptacles (2) to the central unit (3) when the receptacles (2) are at the intended depth of operation.

12. The method according to any one of claim 10 and 11, wherein the intended depth of operation is the maximum depth of operation of the receptacles (2).

13. The method according to claim 10, wherein the method comprises prior to step d):

- unlock at least one receptacle (2) from the central unit (3) prior to pumping water out of the at least one receptacle (2); and

14. The method according to claim 13, wherein the method comprises to lock the at least one receptacle (2) to the central unit (3) at a maximum floating level of operation.

15. The method according to any one of claim 13 and 14, wherein the method comprises to:

- pump water out of the remaining receptacles (2) such that the remaining receptacles (2) ascend in the water column (91), and thereby the complete central unit (3) and the at least one receptacle (2) are lifted above the water surface (9).