WO2024242571A1

WO2024242571A1 - A method of forming a closed fish farming tank shell and a fish farming tank shell

Info

Publication number: WO2024242571A1
Application number: PCT/NO2024/050122
Authority: WO
Inventors: Cato LYNGØY; Åsmund Hellesøy; Trond Severinsen; Magne BJØRKHAUG
Original assignee: Ovum AS
Current assignee: Ovum AS
Priority date: 2023-05-22
Filing date: 2024-05-21
Publication date: 2024-11-28
Anticipated expiration: 2025-11-22
Also published as: NO348383B1; NO20230592A1

Abstract

The invention is a method for building a fish farming tank shell (1) as a composite rotational ellipsoid, partially or fully submersible in water, comprising: - Establishing a vertical axis (1A) in the operational position of the fish farming tank shell (1) where the method comprises the steps - manufacturing a lower half-shell part (IL) that is rotationally symmetric about the vertical axis (1A), - manufacturing an upper half-shell part (1U) that is rotationally symmetric about the vertical axis (1A), wherein the lower and upper half-shell parts (IL, 1U) are produced by relative rotation about the vertical axis (1A) in relation to a shell-forming apparatus comprising at least one roving guide head (62, 82), and -joining the lower half-shell part (IL) and the upper half-shell part (1U) at a common equatorial region (12, 12U, 12L).

Description

METHOD OF FORMING A CLOSED FISH FARMING TANK SHELL AND A

FISH FARMING TANK SHELL

Method for forming a closed fish farming tank shell

Introduction

The present invention provides a fish farming tank shell and a method for producing it.

The applicant holds several patents related to egg-shaped fish farming tanks. These patents cover various aspects, including the tank's circulation system, water replacement mechanisms, the relative positions of inlets and outlets, and both internal and external buoyancy ballast tanks. The tanks are predominantly egg-shaped. In geometric terms, the egg-shaped tanks can be approximated as having a blunt, half rotational ellipsoid bottom portion and a pointed, half rotational ellipsoid top portion of the same diameter. This vertical, egg-shaped design offers several advantages when placed in the sea, such as improved towing, heaving, and rolling properties. It has been observed that this shape significantly reduces the tank's vulnerability to waves, thereby maintaining calm conditions within the buoyancy volume. This leads to minimal splashing and thus promotes better fish welfare. In practice, improved fish welfare has been demonstrated, resulting in significantly reduced mortality rates in fish ranging from 150 grams to 1000 grams. This has been evidenced in experiments involving 50,000 individuals in the closed fish farming tank. As the tank is closed, you have complete control over the inflow and outflow of water, effectively eliminating issues such as the introduction of salmon lice.

The fish farming tank shell is designed and equipped for farming fish, particularly salmon, but it can also accommodate other commercially viable species. The applicant has developed a prototype fish farming tank named E2000, as illustrated inFig. lb. This tank features an egg-shaped shell with a vertical axis, the tip oriented upwards and the blunt end downwards. It stands 22 meters tall with a diameter of 15 meters. The E2000 includes a floating collar with crew ports and mezzanine levels, buoyancy ballast tanks, a dead fish tank, pumps and pipelines, and a bottom module with a dead fish sump and a concrete base for construction and transport on barges. Constructed at a yard in 01ve, Hardanger, the E2000 fish farming tank holds a water volume of 2000 m³. It was launched into the fjord at Molde in the summer of 2022 and stocked with 50,000 smolts weighing 150 grams each. In its first batch, it successfully produced 48,650 salmon, each exceeding 1 kg in size. The mortality rate was an exceptionally low 0.7%, significantly lower than the rates typically observed in open sea cages.

The prototype E2000 was built using an egg-shaped fish farming tank shell made from 8 vertically placed pairs of upper and lower sector-shaped sandwich sections formed by vacuum casting. These sections were mounted on a cylindrical concrete base, and the vertical joints were milled out, glued, and welded. Each section was laid out in a vacuum mould with glass fibre mats for the inner shell. The sandwich layer consisted of Divinycell mats cut into shape and joined together, with glass fibre mats for the outer shell. Vacuum suction was applied in a vacuum bag, and resin injection with curing polyester was used to solidify the structure. Joining the sandwich sections is a time-consuming precision task. It involves milling out joints and grooves, welding the inner skin edge to edge joining and gluing the intermediate layer, and then joining and welding the outer layer. The vacuum casting and assembly process required a substantial amount of manual labour and many man-hours to build the prototype. This process can likely be made more cost-effective through automation and the use of robots.

Background technique

WO 2021154087 Al, with a priority date of 28/01/2020, and assigned to Hauge Aqua AS, is one of the applicant's patents. It describes a fish farming tank with a closed, rigid shell designed to have a vertical main axis. The shell is predominantly ellipsoidal or egg-shaped. The rigid shell of the tank is designed to have the shape of a vertical long axis rotational ellipsoid. WO 2017026899 Al, with a priority date of 12/08/2015, by Hauge Aqua AS, describes a fish farming tank comprising an egg-shaped shell (1) with a substantially vertical long axis. This shell forms a rigid and closed tank that floats partially submerged in the sea.

US 4884709 A, with a priority date of 09/01/1989, by Theta Tech Inc., and expired in 2006, discloses a storage tank having an ellipsoidal shape. This tank is made of a fibre-reinforced plastic material and consists of two shell parts assembled into a tank. The tank comprises two vertically aligned half-shell parts joined by a common flange portion.

US 3661294 A, with a priority date of 10/08/1970, by Owens-Coming Fiberglass Co., and expired in 1989, describes a slightly conical cylindrical storage tank with an end cap, intended for underground storage of petroleum products. The tank is formed of hardened plastic material with reinforcement of various fibres. Roving is used to place a thermoset material layer. The tank is made by forming two halves which are then joined in a common central area.

US 2021002060 Al, with a priority date of 02/07/2020, and published on 07/01/2021, by Ariane Group, DE, describes the manufacture of a thermo-insulated tank for use in a rocket or spacecraft. According to the patent: "An object of US2021002060 is to provide an improved tank for storing liquid or gaseous substances for a spacecraft, such as a rocket or a rocket stage, having good thermal insulation and a reduced weight, while providing effective explosion protection. It has an evacuable sandwich structure that completely encloses its perimeter."

There is a need for a method for the serial production of much larger tanks with an assembled rotary ellipsoid shape, building on the positive results obtained with the "small" tank of 2000 m³, but increasing the volume by, for example, doubling the dimensions to build a large egg- shaped tank. This larger tank would be 44 meters in height and 34 meters in diameter, mainly rotary ellipsoid but preferably egg-shaped. The goal is to construct a much larger tank than the "small" egg-shaped tank of 2000 m³ without internal ribs or flanges. It could have been advantageous to have webs or flanges inside to counteract buckling of the fish farming tank shell, but such webs or flanges are undesirable due to the potential damage and wear they could cause to the fish. Moreover, they would have slowed the rotation of the farming volume, leading to energy loss and requiring increased use of energizers. Additionally, it is difficult to keep an inner surface with flanges clean by automated methods, whereas fouling is less likely on smooth surfaces.

There are patents for the glass fibre spinning of large diameter vertical bearing tanks which are cylindrical in shape with straight or substantially spherical end pieces. GB-A-22333384B discloses a method of manufacturing a storage tank comprising the steps of spraying a first layer onto a mandrel, wherein the first layer is sprayed as a mixture of hardening plastics material and fibres, and mounting theretoa plurality of solid rib-forming forms, for example of polyurethane, which are mounted around the first layer onto the mandrel in separate planes, and then, a second layer, comprising a mixture of plastics material and fibres, is sprayed over the first layer and the rib-formers. The tank with the thereby integrated ribs is then removed from the mandrel. The prior art mandrel is rotated during the application of the first and second layers. The rib-forming moulds are made of polyurethane foam. The fibres of the first and second layers comprise roving, which is wound on. The patent does not address how to solve the problem of removing the mandrel.

However, we have not discovered prior art that facilitates the spinning of a vertically rotational ellipsoidal glass fibre shell of the size desired herein. While it is feasible to construct a mandrel of the required size, doing so would necessitate significant storage space, spinning, and staging of surface plates. Moreover, the mandrel would need to be completely disassembled and removed piece by piece from the fish farming tank shell after serving its purpose. This would render serial production cumbersome. While it is feasible to spin a fiberglass ball on a balloon-like mandrel, and spinning fiberglass roving on a relatively small cylindrical tank with round end caps is straightforward, scaling up existing methods poses challenges. These challenges stem from the risk of buckling, rupture, and collapse of both the mandrel and the structure when the dimensions of the shell surface become very large in relation to the shell thickness, even when considering a relatively rigid sandwich shell. There is also a pressing need to mass-produce such large fish farming tanks to meet market demands for increased farmed salmon production. Additionally, there is a need to transition from open cages to closed cages for reasons of fish welfare, particularly in preventing the ingress and spread of parasites and infections, as well as managing fish sludge and residues.

Brief description of the invention

The invention provides a method for constructing a fish farming tank shell (1) as an assembled rotational ellipsoid, for partial or complete immersion in the sea. The method involves:

- Establishing a vertical axis (1A) in the operational position of the fish farming tank shell (1) characterized by the steps

- Manufacturing a lower half-shell part (IL) that is rotationally symmetrical about the vertical axis (1A), using a first half rotational ellipsoidal mandrel or mould (20L).

- Manufacturing the upper half-shell part (1U) that is also rotationally symmetrical about the vertical axis (1A), using a second half rotational ellipsoidal mandrel or mould (20U).

- Forming the upper half-shell part (1U) with:

- A rigid, wound inner half-shell layer (lUi).

- A spacer intermediate half-shell layer (lUm).

- A rigid, wound outer half-shell layer (lUo).

- Forming the lower half-shell part (IL) with:

- A rigid, wound inner half-shell layer (ILi). and..

- A rigid, wound outer half-shell layer (ILo).

- wherein the lower and upper half-shell parts (IL, 1U) are produced by relative rotation about the vertical axis (1A) relative to a shell-forming apparatus comprising at least one roving guide head (62, 82),

- where spinning with reinforcing fibres of the upper and lower half-shell part (IL) comprises a roving (61, 81) and comprises relative rotation about the vertical axis ( 1 A) relative to the roving guide head (62, 82) of the roving (61, 81) forming the inner half-shell layer (lUi, ILi) and the outer half-shell layer (lUo, ILo)), - where the lower half-shell part (IL) is formed on the first half rotational ellipsoidal mandrel or mould (20L) in the upside-down position of the half-shell part (IL) and is turned to the right position before joining with the upper half-shell part (1U) and

- where the lower half-shell part (IL) and the upper half-shell part (1U) are joined at a common equator portion (12, 12U, 12L)

- where the height of the fish farming tank shell (1) is between 20 and 60 meters and where the diameter of the fish farming tank shell (1) is smaller than the height and is between 15 and 45 meters.

Brief figure explanation

Fig. la depicts a fish farming tank in an approximate side view, as shown inFig. la The illustration showcases a fish farming tank shell (1) along with a top module (5T) designed for ports and equipment. Additionally, there is a bottom module (5B) serving as a base member, with an inlet or outlet positioned downwards, and including any necessary ballast and anchor points. RE: rotational ellipsoid.

Fig. lb showcases the background technique of an egg-shaped farming tank, standing at a height of 22 meters, as described previously. The tank is assembled from 8 upper and 8 lower shell sectors, each of which are vacuum moulded shell parts. FR: float drying/work deck/wastewater treatment plant. VS: vertical joints: weld/glue. VHS: vacuum moulded half shell sectors. E: Ellipsoid equator. HS: horizontal joint: weld/glue. SB: base/ballast.

Fig. 2a, b, c depicts a principled vertical section of a fish farming tank shell according to the invention, as shown inFig. 2a, and vertical section of the lower half shell part shown upside down in Fig. 2b, and vertical section of the upper half-shell part shown in Fig. 2c.

Fig. 3a, b, c present a principle sketch with a vertical section of a sandwich-built fish farming tank shell, according to an embodiment of the invention. Fig. 3a displays the sandwich-shaped lower half-shell part (IL) joined to the sandwich-shaped upper half-shell part at their common equator.

Fig. 3b illustrates an embodiment where the sandwich-shaped lower half-shell part (IL) is formed upside-down, from its equator (12L) at the bottom to its bottom portion (13) at the top. This portion is then inverted to the upright position before assembly with the upper half-shell part (1U), as shown in Fig.. 3a. An advantage of forming the lower half-shell part (IL) upside down with its equator (12L) at the bottom and with decreasing horizontal radius upwards during construction is that it ensures good stability throughout the construction process. This is because all the supplied building material is provided within the largest periphery, which is much better than if it were to be formed with a very small horizontal radius at the beginning and an increasing horizontal radius along the way.

Fig. 3c illustration 3c depicts a vertical section of the upper half-shell part (1U) formed along a straight path. An advantage of forming the upper half-shell part (1U) with its equator (12L) at the bottom and with a decreasing horizontal radius upwards is that it also ensures good stability during the construction process, as all the material supplied is within the largest periphery. Both the upper half-shell part (1U) and the lower half-shell part (IL) are manufactured in substantially the same way but in different shapes, with possible recesses for accommodating a top module (IT) and a bottom module (IB) of varying dimensions.

Fig. 3d illustrates a guiding apparatus (90) for a controlled cement printhead (92) for forming a mandrel or mould (20L, 20U) for the lower, respectively upper shell half (IL, 1U) in one embodiment of the invention on a rotating turntable. Fig. 3e illustrates a simple mechanical implementation of the invention, where there is an axially suspended guiding apparatus (90) with two arms whose sum is constant for an elliptical path, and attaching a cementing head (92) to this, and pumping cement slurry to the cementing head (92).

Fig. 4a shows the whole and parts of an assembled fish farming tank shell (1), which is composed of an upper, slightly sharper rotational superellipsoid shell half (1U) and a lower, slightly sharper rotational superellipsoid shell half (IL). The lower shell half (IL) is formed upside-down on a mandrel (20L) of rotational superellipsoid (half) shape, see Fig. 4b, and turn. Similarly, the upper shell half (1U) is formed on an "upper" mandrel (20U) of half rotational superellipsoidal shape, illustrated in Fig. 4c. Fig. 5 a illustrates an embodiment of the invention showing the formation of the inner, rigid half-shell layer (ILi, lUi). In this process, a roving (61) runs through a polymer fluid (63) in a polymer bath and then moves to a position-controlled roving guide head (62) that places the polymer-wet roving (65) on the relatively rotating half-shell mould (20L, 20U).

Fig. 5b illustrates an embodiment of the invention showing the formation of the intermediate layer (ILm, lUm), known as the sandwich core layer. This is achieved using a controlled winding tape guide (72) that guides a cellular material mat tape (74) onto the rotating substrate, which is the inner rigid fibre-reinforced half-shell layer (ILi, lUi).

Fig. 5c illustrates an embodiment of the invention showing the formation of the outer, rigid half-shell layer (ILo, lUo). In this process, a roving (81) runs through a polymer bath (83) and then moves to a position-controlled roving guide head (82) that places the polymer- wet roving (85) on the relatively rotating sandwich core, which is the intermediate layer (ILm, lUm).

Fig. 5d illustrates an embodiment of the invention where the formation of the lower halfshell part (IL) is terminated near the bottom (the top during the formation of the upside-down half-shell part) to create a recess for mounting a bottom module (5B). This bottom module, after installation, can serve as part of the lifting yoke arrangement together with an equivalent lifting yoke (5L), enabling the lifting and turning of the lower half-shell part (IL) before it is joined with the upper half-shell part (1U). The upper half-shell part (1U) can also have a correspondingly formed recess for a top module (5T), which, for lifting and mounting, can serve as a lifting yoke together with an equatorial lifting yoke (5U).

Fig. 6 illustrates an embodiment of the invention where interposed cylindrical portions (13) can be arranged. These portions have a wall cross-section corresponding to that of the upper half-shell part (1U) and the lower half-shell part (IL). This configuration is useful if more breeding volume is needed temporarily or permanently than that provided by the upper and lower half-she 11 parts (1U, IL).

Embodiments of the invention The invention provides a fish farming tank shell (1). More specifically, the invention provides a fish farming tank shell (1) that is assembled as a rotational ellipsoid and is partially or completely submersible in the sea. It comprises:

- Establishing a vertical axis (1A) in the operational position of the fish farming tank shell (1)

- A lower half-shell part (IL) that is rotationally symmetrical about the vertical axis (1A),

- An upper half-shell part (1U) that is rotationally symmetrical about the vertical axis (1A), where the lower and upper half-shell parts (IL, 1U) are made by relative rotation about the vertical axis (1A) relative to a shell-forming apparatus comprising at least one roving guide head (62, 82). and..

- where the lower half-shell part (IL) and the upper half-shell part (1U) are joined by a common equator portion (12, 12U, 12L). This is how the fish farming tank shell is formed.

The lower half-shell part (IL) is substantially materially continuous around its circumference and terminates at its equator (1 IL). It has the shape of a half rotational ellipsoid around the vertical axis (1A) and terminates near or at its equator (11, 1 IL).

The upper half-shell part (1U) also has the shape of a half rotational ellipsoid around the vertical axis (1A) and is substantially materially continuous around its circumference, terminating near or at its equator (11, 11U), while the lower half-shell part (1U) is blunter than the upper half-shell part (IL), Fig. la, Fig. 2a where the outline of a pure rotational ellipsoid is drawn for comparison, and in Fig. 3a, and Fig. 4a. We have illustrated an adult in Fig. la, Fig. lb, Fig. 2a, etc., to show the size of an embodiment of the fish farming tank shell (1).

The upper half-shell part (1U) is narrower toward the apex than a corresponding pure rotational ellipsoid and has a somewhat longer half-major axis between the equator and the apex than an imagined corresponding pure rotational ellipsoid, with the same total height as the fish farming tank shell (l),Fig. la and Fig. 2a.

The lower half-shell part (IL) is narrower than a corresponding imagined pure rotational ellipsoid and has a somewhat shorter half-major axis than the imagined pure rotational ellipsoid, see Fig. la and Fig. 2a. A fish farming tank according to the invention is shown in an approximate side view inFig. la where a fish farming tank (IT) with a fish farming tank shell (1) and a top module (5T) for ports, equipment, outlets, pumps, and adjustable buoyancy tanks is sketched. Further illustrating Fig. la illustrates a bottom module (5B) as a base part like an "egg cup," with ballast, a sump for dead fish and sludge, a drainage module, a freshwater inlet, an intake filter, and valves. The water intake can be at the bottom and the outlet at the top. The bottom module can include fixed ballast, liquid ballast, and anchoring points.

A fish farming tank according to the invention is shown in a schematic vertical section in Fig. 2a, and vertical section of the lower half shell part shown upside down in Fig. 2b, and vertical section of the upper half-shell part shown in Fig. 2c.

An advantage of the egg shape, where the tip can be air-filled (see WL internal in Fig. la, is that the pitch resistance moment of the egg shape is significantly greater than for a corresponding sphere, which might roll more or less uncontrollably. This is important for the safety of the crew who may need to work on the mezzanine deck or on a collar (not shown in Fig. la but illustrated correspondingly in Fig. lb.

A fish farming tank according to the invention is sketched as a sandwich construction in a schematic vertical section in Fig. 3a, and a vertical section of the lower half-shell part shown upside down in Fig. 3b, and a vertical section of the upper half-shell part (1U) shown in Fig. 3c. It is outlined that the lower half-shell part (IL) is manufactured upside down and then turned before joining with the upper half-shell part (1U) by lifting it and joining the two shell halves (IL, 1U) along their common equator (12L, 12U).

A significant advantage of assembling the fish farming tank shell (1) in this manner is that there will be a single main joint along the equator (11) of the shell instead of all the vertical joints required to join the shell segments in the vertical direction in the existing prototype illustrated in Fig. lb.

Another significant advantage is that since the upper shell half (1U) and the lower shell half (IL) are substantially materially continuous around their circumference, there are no main vertical joints. This allows the use of several manufacturing processes described below that take advantage of this circumferential continuity, either by spinning roving, moulding on a circumferentially continuous mould, or "printing" in a circumferentially continuous direction.

In one embodiment of the invention, the lower half-shell part (IL) is formed on a first half rotational ellipsoid mandrel (20L) in an upside-down position, see for example in, Fig. 3b, and also shown in the alternative in Fig. 4b as a rotational superellipsoid shape, and is then turned to the upright position before joining with the upper half-shell part ( 1U), see Fig. 3a, respectively. Fig. 4a, where the upper half-shell part (1U) is illustrated being formed in Fig. 3c, respectively. Fig. 4c. In one embodiment of the invention, the upper half-shell part (1U) is formed on a second half rotational ellipsoid mandrel (20U), see Fig. 3c, and as rotation superellipsoid mandrel (20U) in e.g. Fig. 4c.

In one embodiment of the invention illustrated in Fig. 3d, the lower (upper), half rotational ellipsoid mandrel (20L, 20U) is formed by casting during relative rotation on a turntable by printing cement slurry from a concrete pump/source (96) via a cement pipeline (94) to a controlled cement printing head (92) moving along a quarter ellipsoid path about the rotation axis (1A) up from the turntable. The mandrel/mould (20L, 20U) is shown during rotating printing halfway through the process. The finished mandrel / mould (20L, 20U) is shown in Fig. 3b, respectively. Fig. 3c.

Fig. 3d illustrates a guiding apparatus (90) for a controlled cement printing head (92) for forming a mandrel or mould (20L, 20U) for the lower, respectively upper half-shell part (IL, 1U) in one embodiment of the invention on a rotating turntable. The guiding apparatus (90, 60, 70, 80) can, in one embodiment of the invention, be an apparatus that can be adjusted in vertical z- and horizontal (radial) x-direction for guiding the controlled head (82, 62, 72, 82).

Fig. 3e illustrates a simple mechanical embodiment of the invention where it is exploited that in a standard ellipse, the sum of two radii from each focus is constant. Therefore, one can have an axially retractable guiding apparatus 90 with two arms whose sum is constant and mount a cementing head 92 on it, if necessary with a small sliding mould, and pump cement slurry to the cementing head (92). This provides a robust alternative embodiment of a device for casting lower or upper mandrels (20L, 20U).

In one embodiment of the invention, the assembled rotational ellipsoid fish farming tank shell (1, IL, 1U) is an assembled egg-shaped shell where the lower half-shell part (IL) has a relatively shorter half-major axis and is blunter than the upper half-shell part (1U), where the upper half-shell part has a relatively longer half-major axis, and with equally long half-minor axes. What we call the equator (12, 12U, 12L), i.e., the largest diameter about axis (1A) of the thus assembled fish farming tank shell (1, IL, 1U), therefore lies somewhat lower in relation to the equator (11) than a pure rotational ellipsoid where both half half-major axes are equally long, seeFig. N.

In one embodiment of the invention, the lower half-shell part (IL) forms a half rotational ellipsoid of the first order, and the upper half-shell part (1U) forms a half rotational ellipsoid of the first order. The upper one is just longer axially than the lower one. The upper halfshell part (1U) generally follows the shape. x²/au² + y²/bu² + z²/cu² = 1 . where x, y, are two horizontal orthogonal coordinates and z is the coordinate along the vertical axis, and where au and bu are equal and make up the radius of the shell half equator (12U). Similarly, for the lower half-shell part (IL), this one generally follows the shape. x²/ai_² + y²/bi_² + Z²/CL² = 1 . where x, y, two horizontal orthogonal coordinates and z are the coordinate along the vertical axis, and where a and b are equal and make up the radius of the lower half of the lower half-shell, (12L), which is equal to the radius of the upper half-shell (1U) so that two halves of the same diameter can be joined together.

One advantage of having the lower half-shell part (IL) blunter is that a larger water volume collects at a deeper water level than for a corresponding ellipsoid shape, which is beneficial for the operational farming volume available.

Another advantage is that by having the upper half-shell part (1U) sharper, i.e., less blunt, a contribution to stabilizing uplifting moment against pitch movements is achieved, as a necessary air volume in the tip of the sharper part of the half-shell (1U) has a greater distance from the overall center of mass of contained water compared to a corresponding pure rotational ellipsoid. A dynamic pitch resistance moment for the assembled rotational ellipsoid fish farming tank shell (1) compared to a pure spherical shape, which inherently has no self-uplifting resistance moment, also arises from rotating the assembled rotational ellipsoid fish farming tank shell about one of the horizontal axes, i.e., pitching, which will require vertical tangential flow along the shell to compensate for vertical radial differences with the surrounding water, resulting in alternating suction and pressure that are compensated by vertical flows to offset the pressure differences, thus providing dynamic flow resistance against rotation. In one embodiment, ballast can be integrated into the lower half-shell part (IL) directly or in a bottom module (5B), and buoyancy ballast tanks can be integrated into an upper part of the upper half-shell part (1U) as internal or external tanks or indirectly as tanks in a top module (5T).

In one embodiment of the invention, the lower half-shell part (IL) forms a half rotational ellipsoid of higher order, i.e., a rotational superellipsoid shape that is wider, where the exponents in the equation are higher than 2. This is shown in Fig. 4b. The lower half-shell part (IL) follows this general shape. x^N/aL^N + y^N/bi_^N + Z^N/CL^N = 1 . where N > 2 and can be a decimal number.

In one embodiment of the invention, the upper half-shell part (1U) forms a half rotational ellipsoid of higher order, i.e., a rotational superellipsoid shape that is wider, where the exponents in the equation are higher than 2. This is shown in Fig. 4c. The lower half-shell part (IL) follows this general shape.

X^M/3L^M + y^M/bL^M + Z^M/CL^M = 1 . where M > 2 and can be a decimal number, and where CL is Cu. M and N do not have to be the same value; for example, N > M in the example shown in Fig. 4b and 4c; with the bottom part being blunter The assembly of the superelliptic rotational ellipsoid fish farming tank shell is shown in Fig. 4a. A significant advantage of this embodiment with a rotational superellipsoid is that it achieves a larger volume than a first-order rotational ellipsoid. Another advantage is that it achieves a slightly higher mass moment of inertia and a slightly larger outer radius of the rotating water masses inside the shell, which can help reduce the energy consumption of water circulators inside the tank relative to the tank's volume compared to a rotational ellipsoid.

In one embodiment of the invention, the upper half-shell part (1U) comprises a sandwich construction:

- a rigid inner half-shell layer (lUi),

- a spacer-forming intermediate half-shell layer (lUm), serving as a sandwich core, and

- a rigid outer half-shell layer (lUo). Please see Fig. 3a and 3c; Fig. 4a and 4c. See also Fig. 5e.

In one embodiment of the invention, the lower half-shell part (IL) comprises a sandwich construction that includes:

- an inner half-shell layer (ILi),

- an intermediate half-shell layer (ILm), serving as a sandwich core, and

- an outer half-shell layer (ILo). See Fig. 3a and Fig. 3b; Fig. 4a and Fig. 4b; and a formation process illustrated in Fig. 5a - 5e.

The formation of the entire sandwich layer (ILi, ILm, ILo) can be achieved using a vacuum bag over the whole setup and vacuum moulding with curing polymer or heat-curing polymer or PET meltable polymer, which is advantageous for recycling.

The formation of the inner, rigid half-shell layer is shown as an example embodiment in Fig. 5a , where a roving (61) runs through a polymer bath (63) and then to a position- controlled roving guide head (62) that places the polymer-wet roving (65) on the relatively rotating half-shell mould (20L), where the roving (61, 81) is wetted with a polymer fluid (63, 83). In an alternative embodiment of the invention, the roving (61, 81) is a commingled yam

- roving (67, 87) comprising dry reinforcement fibres (68, 88) and thermoplastic fibres (69, 89), which require a heat source to temporarily melt the plastic fibres (69, 89) that are between and around the reinforcement fibres. The positional control of the roving guide head (62) can, in one embodiment of the invention, be performed using a guide apparatus (60) where the roving guide head (62) is held, arranged to guide the roving guide head (62) along the intended quarter path determined by the upper or lower ellipsoid. generally following the form x²/ai² + y²/bi_² + Z²/CL² = 1.

Where for example, with y = 0, x and z vary, but with adjustments for position in thickness, if operating on a turntable (100) as shown in Fig. 5a. The polymer-wetted roving (65) can be laid on the half-shell mould (20L) from bottom to top and can preferably be cross-laminated by alternating the laying angle both ways to achieve tensile strength not only around the axis (1A) but also in the vertical direction. The polymer can be self-curing over a given time so that the inner half-shell layer ( 1 Li) cures at ambient temperature and is ready for the next layer, the distance -forming intermediate half-shell layer (ILm).

The distance-forming intermediate half-shell layer (ILm), forming a sandwich core, can be created by spraying a curing polymer foam to a fixed layer of desired thickness. However, it is not easy to control the spraying to the correct thickness. Therefore, in another embodiment, the distance-forming half-shell layer (ILm) can be formed by cutting polymer foam sheets, such as Divinycell or similar PVC material, not very different in shape from those illustrated as shell sectors in Fig. lb, but this involves a lot of cutting of relatively stiff material, joining, and edge gluing to form a continuous material, resulting in much scrap that cannot easily be reused.

In an embodiment shown in Fig. 5b, a foam sheet winding device (7) is illustrated, comprising a controlled winding tape guide head (72) arranged to wind a sandwich coreforming cellular material tape (74) onto the newly formed inner half-shell layer (ILi). The cellular material tape (74) can be wound from a tape drum (76). The winding tape guide head (72) can include an adhesive application device for applying adhesive during the laying of the cellular material tape (74) so that it is glued on during the winding of the intermediate halfshell layer (ILm). The cellular material tape (74) can be produced to be 1/N, e.g., 1/4, of the desired thickness of the intermediate half-shell layer (ILm) so that, for example, N=4 relative rotations of the mould (20L) are required to form the desired thickness of the intermediate half-shell layer (ILm), the so-called sandwich core, and cross-laying can be used to achieve uniformity and bending stiffness and to prevent cracking through the entire half-shell layer (ILm), the sandwich core. The positional control for the winding tape guide head (72) can, in one embodiment of the invention, be executed using a guiding apparatus (70) (which can be the same guiding apparatus as guiding apparatus (60, 80, 90)) where the roving guide head (72) is held, arranged to guide the roving guide head (72) along the intended path determined by the upper or lower ellipsoid and adjusted for the increasing thickness of the shell being formed.

In an embodiment shown in Fig. 5c ,the winding of the outer half-shell layer (ILo) is illustrated. The formation of the outer, rigid half-shell layer (ILo) is shown as an example embodiment in Fig. 5c where a second roving (81) runs through a second polymer bath (83) and then to a second position-controlled roving guide head (82), which lays the polymer-wet roving (85) onto the intermediate half-shell layer (ILm). In one embodiment of the invention, the positional control for the roving guide head (82) is carried out using a guiding apparatus (80 (60, 70, 90)) where the roving guide head (82) is held (and which can be the same as the roving guide head (62)), arranged to guide the roving guide head (82) along the intended path determined by the upper or lower ellipsoid and adjusted for the thickness of the shell as it is wound. The polymer-wet roving (85) can be laid from the bottom up and preferably crosslaminated by alternating the laying angle both ways to achieve tensile strength not only around the axis (1A) but also in the vertical direction. The polymer can be self-curing within a given time, allowing the outer half-shell layer (ILo) to cure at ambient temperature. Alternatively, thermosetting polymer can be used, but thermosetting requires a heating device. The entire setup (ILi, ILm, ILo) for winding the manufacture of the lower half-shell (IL) can be vacuum-suctioned and vacuum-injected under a vacuum bag 66 (not shown).

In Fig. 5d , an embodiment of the invention illustrates the completion of winding the sandwich layers in the half-shell part (IL) so that a recess for a bottom module (5B) is formed. In a similar embodiment, the upper half-shell part (1U) is sandwich-constructed in the same manner as described above for Figures Fig. 5a - 5e, where only the major axis in the ellipsoid differs, and where a recess and insertion of a top module (5T) are created.

Several significant advantages of the invention for the sandwich construction method are evident: We now have a plausible method where the size of the manufactured fish farming tank shell is no longer a constraint: the moulds (20L, 20U) can be printed with cement on a slowly rotating turntable, smoothed, and surface-treated for release properties and tightness. A winding apparatus for applying by relative rotation for winding the first roving (61) becomes of manageable size, a winding apparatus for a strip of cell material (74) becomes of manageable size, and the cell material strip (74) can be prepared on a drum with a sufficiently large bending radius for the cell material in the desired thickness. Both the sandwich core material and the cell material strip (74) can advantageously be produced at a local facility at the construction site, saving on transportation costs.

The upper half-shell part (1U), see Fig. 5e, is formed as a sandwich construction in a similar manner to the lower half-shell part (IL), but in an embodiment with a top module (5T) instead of a bottom module ( B).

The bottom module (5B) can include a lifting frame designed to bear part of the weight of the lower half-shell part (IL) along with a ring-shaped lifting yoke (5L) that can be installed on the turntable (100) before the construction of the sandwich shell, see Fig. 5d and Fig. 5e. Similarly, the same can be done with the upper half-shell part (1U), see Fig. 5e. This makes it manageable to lift and flip the lower half-shell part (IL), place it down with the bottom module (5B) as a base, and to lift and assemble/weld the upper half-shell part (1U) onto the lower half-shell part, and then launch the entire structure for outfitting into a complete fish farming tank (IT). The top module (5T) and bottom module (5B) can primarily be fully equipped before installation in their respective half-shell parts to form a fish farming tank (IT), see Fig. la, Fig. 5e, and Fig. 6. The top modules (5T) and bottom modules (5B) can be mass-produced elsewhere in the yard than where the half-shell parts (1U, IL) are built. In one embodiment of the invention, the half-shell part (IL) can be lifted and/or turned partially submerged in water in a dock where they are produced to reduce the forces required for lifting and turning over.

In one embodiment, cylindrical shell sections (13) can be inserted in the equatorial part (12) between the two half-shell parts (IL, 1U), see Fig. 6. Cylindrical shell sections (13) are easy to manufacture in a sandwich structure on a cylindrical mandrel, compared to the lower and upper half-shell parts (IL, 1U), and the mandrel can be easily lifted out of a purely cylindrical mandrel.

With the described method, we have taken steps to build a fish farming tank that is at least twice as large as the egg-shaped or ellipsoidal fish farming tanks known from prior art, but in an economically and technically feasible manner. Mass production can be carried out to meet market needs in an economically sustainable way. Procurement of plastic materials can be wholly or partially done through local recycling of fiberglass, and recycling of melted plastic or plastic pyrolysis and the production of new plastic from pyrolyzed material. Recycling the fish farming tank shell made of plastic materials can provide many environmental and economic benefits.

Component list

Claims

1. A method for constructing a fish farming tank shell (1) as a composite rotation ellipsoid, for partial or full immersion in the sea, comprising

- a vertical axis (1A) in the operational position of the fish farming tank shell (1) characterized by the steps

- Manufacturing the upper half-shell part (1U) that is rotationally symmetrical about the vertical axis (1A), using a second half rotational ellipsoidal mandrel or mould (20U).

- wherein the upper half-shell part (1U) is formed having:

- A rigid, wound inner half-shell layer (lUi).

- A spacer intermediate half-shell layer (lUm).

- A rigid, wound outer half-shell layer (lUo).

- and wherein the lower half-shell part (IL) is formed having:

- a rigid, wound inner half-shell layer (ILi), and

- A rigid, wound outer half-shell layer (ILo).

- wherein the lower and upper half-shell parts (IL, 1U) are formed by relative rotation about the vertical axis (1A) relative to a shell-forming apparatus comprising at least one roving guide head (62, 82),

- where spinning with reinforcement fibres of the upper and lower half-shell parts (IL) involves a roving (61, 81) and comprises relative rotation about the vertical axis (1A) with respect to the roving guide head (62, 82) for the roving (61, 81) wherein the inner half-shell layer (lUi, ILi) and the outer half-shell layer (lUo, ILo) are formed,

- where the lower half-shell part (IL) is formed on the first half rotational ellipsoid mandrel or mould (20L) in the upside-down position, and is flipped to the upright position before assembly with the upper half-shell part (1U), and

2. The method according to claim 1, wherein the assembled rotation ellipsoid of the fish farming tank shell is egg-shaped with the lower half-shell part (IL) having a relatively shorter long half -axis being broader than the upper half-shell part (1U) with a relatively longer long half -axis, and with equally long short half -axes.

3. The method according to claim 1 or 2, wherein the assembled rotation ellipsoid of the fish farming tank shell is egg-shaped with the lower half-shell part (IL) formed on the lower, first half rotational ellipsoid mandrel or mould (20L) having a relatively shorter long half -axis being broader than the upper half-shell part (1U) formed on the upper, second half rotational ellipsoid mandrel or mould (2 OU) having a relatively longer long half -axis, and with equally long short half -axes.

4. The method according to any one of claims 1 - 3, wherein the lower half-shell part (IL) is formed with - an intermediate half-shell layer (ILm).

5. The method according to any one of claims 1 - 4, comprising forming recesses for a top module (5T) and a bottom module (5B).

6. The method according to any one of claims 1 - 5, wherein the lower half-shell part (IL) forms a half rotation ellipsoid of the first order, and wherein the upper half-shell part (1U) forms a half rotation ellipsoid of the first order.

7. The method according to any one of claims 1 - 5, wherein the lower half-shell part (IL) forms a half rotational ellipsoid of higher order, and wherein the upper half-shell part (1U) forms a half rotational ellipsoid of higher order.

8. The method according to any one of the preceding claims 1 - 7, where the roving (61, 81) is impregnated with a polymer fluid (63, 83).

9. The method according to any one of the preceding claims 1 - 7, where the roving (61, 81) is a commingled yam - roving (67, 87) comprising dry reinforcing fibres (68, 88) and thermoplastic fibres (69, 89).

10. The method according to any one of the preceding claims, where the formation of the lower half-shell part (IL) and/or the upper half-shell part (1U) comprises applying the intermediate half-shell layer (ILm, lUm) by spraying.

11. The method according to any one of the preceding claims 1 - 9, where the formation of the lower half-shell part (IL) and/or the upper half-shell part (1U) comprises applying the intermediate half-shell layer (ILm, lUm) by the application of pre-cut rigid foam mats (79).

12. The method according to any one of the preceding claims 1 - 9, wherein the formation of the lower half-shell part (IL) and/or the upper half-shell part (1U) comprises applying the intermediate half-shell layer (ILm) by spinning with a cellularmaterial mat band (74) of relatively rigid foam mat material guided onto the relatively rotating inner half-shell layer (ILi, lUi) before forming the outer half-shell layer (ILo, lUo).

13. The method according to any one of the preceding claims 1 - 12, where the cellular material mat band (74) of relatively rigid foam mat material is stored on and wound off a mat band drum (13) with the cellular material mat band (74) while being spun via a controlled spinning band guide head (72) onto the inner half-shell layer (ILi, lUi).

14. The method according to any of the preceding claims, wherein the rigid foam material is rigid polymer foam.

15. The method according to any of the preceding claims, where the lower mandrel or mould (20L) comprises at least one layer of reinforced concrete.

16. The method according to any of the preceding claims, where the upper mandrel or mould (2 OU) comprises at least one layer of reinforced concrete.

17. The method according to any of the preceding claims, where the lower and/or upper mandrel or mould (20L, 20U) is formed by 3D printing of cement from a relatively rotating controlled cement printing head (92) relative to a turntable (100), without an underlying mould for the mandrel or mould (20L, 20U).

18. The method according to any of the preceding claims, where the height of the fish farming tank shell (1) is between 30 and 50 meters and where the diameter of the fish farming tank shell (1) is less than the height and between 18 and 40 meters.

19. The method according to any of the preceding claims,

Where the height of the fish farming tank shell (1) is between 40 and 44 meters, for example 42 meters and where the diameter of the fish farming tank shell (1) is less than the height and between 32 and 36 meters, for example 34 meters.

20. A fish farming tank shell (1) that is a composite rotation ellipsoid and partially or fully submersible in water comprising:

- where the lower half-shell part (IL) and the upper half-shell part (1U) are joined by a common equator portion (12, 12U, 12L).

21. fish farming tank shell (1) according to claim 20, wherein the lower half-shell part (IL) is formed on a first half rotational ellipsoidal mandrel or mould (20L) in the upside-down position of the half-shell part (IL) and turned to the right position prior to joining with the upper half-shell part (1U).

22. Fish farming tank shell (1) according to any of the preceding claims 20-21, wherein the upper half-shell part (IL) is formed on a second, half -rotational ellipsoidal mandrel or mould (20U).

23. Fish farming tank shell (1) according to any of the preceding claims 20 - 22, where the assembled rotational ellipsoid of the fish farming panshell is egg-shaped with the lower half-shell part (IL) with a relatively shorter long half-axis being more blunt than the upper half-shell part (1U) with a relatively longer half-axis, and with equal long half -major axes.

24. The fish farming tank shell (1) according to claim 23, wherein the lower half-shell part (IL) forms a first-order half rotational ellipsoid, and wherein the upper half-shell part (1U) forms a first-order half rotational ellipsoid.

25. The fish farming tank shell (1) according to claim 23, where the lower half-shell part (IL) forms a half rotational ellipsoid of higher order, and where the upper half-shell part (1U) forms a half rotational ellipsoid of higher order.

26. Fish farming tank shell (1) according to any of the preceding claims 20 - 25, where the upper half-shell part (1U) comprises

- a rigid inner half-shell layer (lUi),

- A spacer intermediate half-shell layer (lUm). a rigid, outer half-shell layer (lUo).

27. Fish farming tank shell (1) according to any of the preceding claims 20-26, where the lower half-shell part (IL) comprises

- an inner half-shell layer (ILi), and

- an outer half-shell layer (ILo).

28. Fish farming tank shell (1) according to claim 27, where the lower half-shell part (IL) comprises

- an intermediate half-shell layer (ILm).

29. Fish farming tank shell (1) according to claim 26, 27, or 28, where spinning with reinforcing fibres of the lower half-shell part (IL) and/or the upper half-shell part (1U) comprising a roving (61, 81) involves relative rotation about the vertical axis (1A) in relation to a roving guide head (62, 82) for the roving (61, 81) for the formation of the inner half-shell layer (ILi) and/or the outer half-shell layer (ILo).

30. The fish farming tank shell (1) according to claim 26, 27, or 28, where the roving (61, 81) is wetted with a polymer fluid (63, 83).

31. Fish farming tank shell (1) as claimed in claims 26, 27, or 28, wherein the roving (61, 81) is a commingled yam roving (67, 87) comprising dry reinforcement fibres (68, 88) and thermoplastic fibers (69, 89).

32. Fish farming tank shell (1) according to claim 26 - 31, where the formation of the lower half-shell part (IL) and/or the upper half-shell part (1U) comprises applying the intermediate half-shell layer (ILm, lUm) by spraying.

33. Fish farming tank shell (1) according to claim 26 - 31, where the formation of the lower half-shell part (IL) and/or the upper half-shell part (1U) comprises applying the intermediate half-shell layer (ILm, lUm) by applying cut rigid foam mats (79).

34. Fish farming tank shell (1) according to claim 26 - 31, wherein the formation of the lower half-shell part (IL) and/or the upper half-shell part (1U) involves the application of the intermediate half-shell layer (ILm) by spinning with a cellular material mat band (74) of rigid foam mat material guided onto the relatively rotating inner half-shell layer (ILi, lUi) before the formation of the outer half-shell layer (ILo, lUo).

35. The fish farming tank shell (1) according to claim 34, wherein the cellular material mat tape (74) of rigid foam mat material is stored on and wound off a mat tape drum (13) with the cellular material mat tape (74) while spinning via a guided winding tape guide head (72) on the inner half-shell layer (ILi, lUi).

36. Fish farming tank shell (1) according to any of claims 33 - 35, wherein the rigid foam material is polymer foam.

37. Fish farming tank shell (1) according to any of the preceding claims 20 - 36, where the lower mandrel or mould (20L) comprises at least one layer of reinforced concrete.

38. Fish farming tank shell (1) according to any of the preceding claims 20 - 37, where the upper mandrel or mould (2 OU) comprises at least one layer of reinforced concrete.

39. Fish farming tank shell (1) according to any of the preceding claims 20 - 38, where the lower and/or upper mandrel or mould (20L, 20U) is formed by 3D printing of cement from a relatively rotating controlled cement printing head (92) relative to a turntable (100), without an underlying mould for the mandrel or mould (20L, 20U).

40. Fish farming tank shell (1) according to any of the preceding claims 20 - 39, where the height of the fish farming tank shell (1) is between 20 and 60 meters and where the diameter of the fish farming tank shell (1) is smaller than the height and is between 15 and 45 meters.

41. Fish farming tank shell (1) according to any of the preceding claims 20 - 40, where the upper shell half (1U) is a half rotational super ellipsoid that is somewhat sharper than the lower shell half (IL) which is a relatively blunter half rotational super ellipsoid.