NO346229B1

NO346229B1 - Device for addition of a liquid to water

Info

Publication number: NO346229B1
Application number: NO20200735A
Authority: NO
Inventors: Helge Bullgård
Original assignee: Redox As
Priority date: 2020-06-23
Filing date: 2020-06-23
Publication date: 2022-05-02
Also published as: NO20200735A1; GB202108990D0; GB2598453B; GB2598453A; CL2021001670A1; CA3122832A1

Description

Device for addition of a liquid to water.

The invention relates to a device for distribution of a liquid to a volume of water, and a method for distributing a liquid in water by using the device, according to the preamble of the independent claims.

Aquaculture and fish farming is a large industry, and in 2018 more than 1,3 million tons of salmon and trout were taken out from fish cages, this corresponds to about 86 million individual fish, and a value of more than 67 billion NOK. Most of these fish were grown in fish cages in the sea, surrounded by nets hanging from the surface of the sea. When the fish in a fish cage should be removed, the net is normally raised, and the fish will be pressed together as the volume reduces. A pipe connected to a pump, often a suction pump, is introduced into the net cage, and fish and water is pumped or sucked out of the fish cage. Further, an extra wall may be used to reduce the volume of the fish cage even further. Such a wall is arranged close to the fish net at a part of the circumference of the cage, and then drawn across the cage until only a small volume is remaining. The small volume is surrounded by the fish net, the raised bottom and the extra wall and any fish in this small volume may more easily be removed by the tube. Both the raising of the bottom and the use of an extra wall are methods well known by a skilled person.

A well known problem related to aquaculture is diseases and parasites, and the fish may need treatment. The treatment, for instance with chemicals, fresh water and/or mechanical treatment may be carried out during transfer of the fish from the fish cage to a well boat or to another cage, and in such cases the net is raised during removal of the fish from the cage. Another type of treatment includes addition of chemicals to the water in the fish cage, and in order to reduce both the exposure time and amount of chemicals needed, the net is raised to reduce the volume of water in the fish cage. If an open fish cage is used water may flow through openings of the net, and in such case, a watertight cover may be added on the outside of the cage before chemicals are added. Further, substantial care must be taken during addition of chemicals, to avoid high local concentrations of chemicals which may be harmful to the fish.

When the fish net is raised and the fish are pressed close together, the fish are put under stress. The amount of water available per fish is reduced, and the quality of the water will be substantially reduced, even with open cages where water may flow through the net. Reduced quality of the water may also occur in closed fish tanks onshore or on a boat. The stress and reduced quality of the water reduces the fish welfare and the mortality increases. It may even influence the quality of the meat if the fish after such handling is slaughtered.

Another problem is related to fouling and algal bloom, as the flow of fresh water through the net of the fish cage may be blocked, and thus the oxygen level in the fish cage may be substantially reduced. Further, a skirt or bag of material preventing water to flow through the net may be arranged around the whole or parts the cage to prevent organisms, pollutions, poisons or the similar in the water around the cage to enter the cage. In such cases there is an immediate need for supply of oxygen to the cage.

Norwegian patent 341708 describes a well boat having a pipe wherein one end is arranged for removal of water from the fish cage, and the second end is arranged to add oxygenated water to the cage, as oxygen is added to the pipe through an ejector. However, this method requires that a specific boat is available, which may not be the case if addition of oxygen is needed urgently as described above. Further, the oxygenated water will only be added to the area close to the ship, which may not be the position in most need for oxygen.

Further, there is a problem when the cage bottom is raised and/or an extra wall is being used, that the fish net gets entangled or sucked into the pipe removing fish and water. This will prevent further removal of fish and water, and the pump must be switched off before the net is removed and the pumping may resumed. This may also create damage to the net and if a hole is created, fish may escape. Further, stopping and resuming is time consuming and fish may get stuck in the entangled net, and be injured. These problems will increase if an extra wall is used to reduce the volume even further, as described above.

EP 2198704 describes a system which may be used to add oxygenated water to a fish cage. The oxygenated water flows into the water of the cage through a perforated pipe which may be shaped as a ring. However, this system may not be used to prevent the fish net from getting entangled in the pipe removing fish and water.

The main object of the invention is thus to provide a device and a method to add a liquid to a volume of water, such as a fish cage or a fish tank, and to ensure quick and thorough mixing of the liquid and water. Another object is that the liquid should be oxygenated water, and that it should be added to the water in a fish cage during removal of the fish. Yet another object is to prevent the net from being entangled or sucked into the removal pipe. Further, it is an object that the device should be easy and quick to install/uninstall and to use, not involve any danger to the users, and be easy to clean and/or disinfect. A final object is that the device should not require a lot of space during storage and transportation, and be easily combined with standard equipment on a fish well boat.

The above said objects are met by a device and a method according to the characterizing part of enclosed independent claims. Further optional features are stated in the dependent claims.

The invention is related to a device for distribution of a liquid to a volume of water and to prevent a fish net from entangling in a pipe removing fish and water. The device has a wall surrounding an inner chamber and separating the chamber from the outer environment of the device. An inlet to the inner chamber and a number of outlets from the inner chamber are arranged in the wall, wherein the outlets are distributed on the outer surface of the device. Further, the device comprises a ballast increasing the total weight of the device under water, to more than 10 kg.

The wall surrounding the inner chamber, and separating it from the outer environment of the device, is preferably also the wall defining the outside of the device. The wall is made of a material being sufficiently strong to retain the shape of the chamber and the shape and size of the inlet and outlets even when the liquid supplied to the chamber has higher pressure than the environment of the device. A preferred material of the wall is metal or plastic, more preferred PE having a density above 0,9 g/cm<3>, and the walls may have a thickness of 4 - 8 mm, preferably about 6 mm.

In a preferred embodiment, the outer shape of the device and the shape of the inner chamber are about the same, and then the wall will have the same thickness around the whole chamber. However, the wall may be thicker in areas where the device is fastened to other equipment, such as a line to raise and lower the device. In a preferred embodiment, the inner chamber is shaped as a ball, and preferably as a sphere, however chambers shaped as ellipsoids and oviforms should also be included in the expression "shaped as a ball". The outer shape of the device may also correspond a "ball" or a buoy, such as a net bouy.

The inlet is arranged to be connected to a supply tube, for supply of liquid to be distributed in the volume of water. The liquid may for instance be chemicals for treating or vaccinating fish in the fish cage. In a preferred embodiment, the liquid is oxygenated water for adding oxygen to the water in the volume fish cage or tank to improve the welfare and health of the fish in general, and/or to reduce stress during handling as mentioned above. By "enriched with oxygen" it is herein meant that the water to be added contains more oxygen than the water in the volume. The expression includes both embodiments wherein oxygen gas is added to the water, and embodiments where air is added to the water. The oxygen or air may be added from a compressor, ejector, venturi valve and/or any other convenient method known to a skilled person. The process of adding oxygen may be carried out on a boat, barge such as feeding barge on a fish farming plant, or even on the floating collar of the fish cage if desired. A combination of liquids, such as chemicals and oxygenated water may also be used.

By adding water enriched with oxygen to the volume of water, oxygen will be added to the water in the volume due to mixing of the liquids. If gas or air is added directly, it will rise too fast and escape from the surface rather than enriching the water in the volume. Further, if gas or air is added directly there will be local differences in the concentrations, and these differences may stress and cause discomfort to the fish. Yet another advantage by adding water enriched with oxygen is that the risk of hyperoxia increases when adding oxygen directly to the water, rather than adding oxygenated water.

The volume of water may be any volume, including a tank on a well boat, but it is preferably a fish cage, and the liquid is added to the volume by lowering a device according to the invention into the water in the volume.

In the context of this application "water" should be understood to be both fresh water and sea water or a mixture of these.

A number of outlets are arranged in the wall, distributed on an outer surface of the device, in order to distribute the liquid added to the chamber through the inlet, to the surroundings of the device. The outlets are preferably arranged to have the same resistance or pressure drop, i.e. they have the same cross section area, and thus equal amounts of liquid are flowing through each outlet. In a preferred embodiment, all outlets have the same size and shape. In an alternative embodiment, the outlets being further away from the inlet may be larger than the outlets being closest to the inlet, to ensure that equal amounts of liquid are flowing through every outlet. Any differentiation would depend i.a. on the liquid in question, the pressure difference between the liquid to be added and the water outside of the device, which is obvious to a skilled person.

The outlets may have any shape depending on the desired use, and will create a turbulent flow on the outside of the device, which increases the mixing of the liquids. In an alternative embodiment the outlets are conical either by having a larger cross section at the outer surface of the device which will make the outlet function as a spreader nozzle, of by having a smaller cross section at the surface of the device which will make the outlet function as a centring nozzle.

The outlets are distributed on the surface of the device, and once the device is lowered in the volume of water, the liquid will be distributed both from a lower side and an upper side. In a preferred embodiment, the outlets are evenly distributed on the whole surface of the device.

In a preferred embodiment, the outlets are straight holes in the wall surrounding the inner chamber, and as the holes have the same shape and size the pressure drop will be equal for all holes. In a more preferred embodiment, the diameter of the hole should be at least 0,5 cm, preferably at least 1 cm, when the the inner chamber is shaped as a ball having a diameter about 45 cm.

As described above, there is a problem when fish cages are emptied that the fish net may be sucked into the pipe removing fish, and thus as a device according to the present invention has a density higher than water, it will sink and may be used to keep the net away from the pipe.

The device further comprises a ballast, to increase the total density and to ensure that the device will sink in water regardless of the material of the wall and the liquid added to the chamber. The ballast increases the total weight of the device by at least 10 kg, more preferred more than 50 kg, when the device is weighted under water. How much higher than water the total density of the device should be, or how much ballast should be added, depends i.a. on the material of the wall, the intended use of the device, the suction power of the pipe removing fish, and the liquid to be added. This is obvious to a skilled person.

By "total density" it is herein meant density of the device as a whole, that is the weight of the device divided by the volume of the total device. When the total density of the device is higher than the density of water, the device will sink in water. The total density is preferably higher than the density of water, even when the liquid to be added to the water has a density less than water.

Ballast may be moulded into the device, as a part of the wall or the wall may be made of a material being sufficiently thick or dense to achieve the desired weight or density. In a preferred embodiment, the device comprises a connection element configured to be attached to a separate weight, wherein both the weight and the connection element may constitute parts of the ballast. The connection element may be arranged at any site on the outer surface of the device, however, it is preferred to arranged the connection element on a side opposite to the inlet. In such a way the inlet may be at an upper part and the connection element may be at a lower part when the device is submerged in a volume of water.

In an alternative embodiment, the connection element is arranged on the outside of the device, for instance as a bolt or nut with threads, and the weight is provided with a corresponding threaded part, whereby the weight is attached to the device by screwing the parts together.

In an alternative embodiment, the connection element is arranged through the wall defining the inner chamber, having one part of the element inside the chamber, and another part on the outside of the device.

In a preferred embodiment, a passage to accommodate a shaft, is arranged through the centre of the device, the passage is defined by walls separating the passage from the inner chamber. In such embodiment, the connection element of the device is a shaft accommodated in the passage, wherein the weight is attached to the shaft in one end and the shaft is attached to the device, preferably the wall defining the inner chamber, in the other end.

When the device according to the invention has connection elements configured to attach the weight, the wall defining the inner chamber and the weight may be produced separately, and possibly of different materials. Further, in alternative embodiments wherein the connection elements are releasable, the ballast may be adjusted according to the operation in question, simply by replacing one weight by another.

In a preferred embodiment, the device may further comprise a member for attaching a line to raise and lower the element. Such a member may for instance be a closed eye or eyelet, and if the device comprises a passage for accommodating a shaft, an end of the shaft may also constitute the member.

Depending on the type of tube and attachment, the tube attached to the inlet for supply of liquid, may also be act as the line used to raise and lower the device in the water. The line, and thus the position of the device in the volume of water, may be controlled manually by manpower or by a winch. In a further embodiment, the line is attached to a crane, and thus the device may be moved in three dimensions in the volume. In yet another embodiment, the line is attached to a pipe removing fish from the tank, and thus the device will be positioned vertically below the pipe at all times. By positioning the device conveniently in the volume, it may add liquid to the most needed area and/or keep the net away from the suction pipe.

In a more preferred embodiment, the shaft may be a threaded shaft, and thus both the weight and the member for attaching a line may be screwed onto the shaft until the shaft is safely secured in the passage of the member.

In a preferred embodiment, the weight is designed corresponding to the device, but the inner chamber is filled with a sufficient amount of ballast. The ballast material may be concrete, metal such as steel, sand, preferably fine-grained sand or any other suitable material. In a more preferred embodiment, the weight is provided with an opening to the inner chamber, to adjust the amount of ballast and thereby the total density of the device. The inlet should preferably be arranged in such a way that the amount of ballast material may be adjusted without releasing the weight from the connection means.

In a preferred embodiment, the weight is provided with a passage similar to the device, to accommodate a shaft, and then the same shaft may be inserted in both passages, fastened to the weight in one end and to the device in the other end.

The invention is also related to a method for distributing liquid to a volume of water, by using a device as defined above. The method comprises the following steps: i) connecting a tube to the inlet of the chamber,

ii) submerging the device into the water,

iii) adding liquid to the tube.

In a preferred embodiment, the method further comprises a step for attaching a weight to the device, either before step i) or before step ii).

In yet a preferred embodiment, the method further comprises a step for adjusting the position of the device in the volume of water.

Reference throughout the specification to “one embodiment” or “an embodiment” "one aspect" or "an aspect" means that a particular feature, structure, or characteristic described in connection with an embodiment and/or aspect is included in at least one embodiment of the subject matter disclosed. Thus, the appearance of the phrases “in one embodiment” or “in an embodiment”, or "in one aspect" or "in an aspect" in various places throughout the specification is not necessarily referring to the same embodiment. Further, the particular features, structures or characteristics may be combined in any suitable manner in one or more embodiments.

Description of the figure

The invention will now be described with the help of the enclosed Figures, showing a preferred embodiment of a device according to the invention. The different parts of the figure are not necessarily to scale in relation to each other, as the diagram is merely for illustrating the invention.

The following description of an exemplary embodiment refers to the drawing, and the following detailed description is not meant or intended to limit the invention. Instead, the scope of the invention is defined by the appended claims.

In the following an example of a preferred embodiment of a device for adding and distributing liquid to a volume of water is described, by way of the following drawings wherein;

Figure 1 shows a device and weight according to the invention, and

Figure 2 shows a longitudinal cross section of the device and weight as shown in Figure 1.

Figure 1 and 2 shows a device comprising a wall 1 surrounding an inner chamber 2. The inner chamber 2 is shaped as a ball, and designed to accommodate a liquid added through an inlet 3 arranged in the wall. A number of outlets 4 are arranged through the wall 1, to allow the liquid to flow out of the chamber 2. The outlets are distributed in the wall, and thus any liquid added to the device through the inlet will be distributed to the surroundings of the device. In the shown embodiment, the wall 2 is equally thick along the whole device, and the outer shape of the device is a ball.

In the shown embodiment, the outlets 4 are circular holes arranged along lines (two lines shown in the Figures) from an upper part to a lower part of the device, and in this way the mixture between the liquid added to the device and the water surrounding the device will be substantially increased compared to adding the liquid through one single outlet. The outlets 4 have the same shape and size, and as the wall has even thickness, water will flow evenly through the holes.

To increase the total density of the device to be higher than water, the device further comprises a weight 5. In the shown embodiment, the weight is a separate part, shaped as a ball with a wall as described above for the device, and the inner chamber 6 is partly filled with ballast, shown as concrete 7. The weight also has an opening 8, for addition or removal of ballast material to/from the inner chamber of the weight.

The device has a connection element configured to be attached to the weight, shown as a passage 9 arranged through both the centre of the device and through the weight, and a shaft 11 accommodated in the passage. The passage 9 is defined by walls 10, 16 separating the passage from the inner chambers 2, 6. One end 11A of the shaft is fastened to the weight, and the other end 11B is fastened to the opposite side of the device. The fastening may be performed in many ways which will be obvious to a skilled person, for instance with a bolt, disk and/or nut.

The end 11B of the shaft is provided with a member, shown as an eyelet 15, being used to attach a line to raise and lower the device. In the shown embodiment, the shaft 11 has threads in both ends, whereby a disk 12 and nut 13 are connected to the end 11A of the shaft, and a disk 14 and the eyelet 15 are connected to the other end 11B. In this way, the weight is secured to the device, and the device may be used to keep a net away from any suction pipe.

In a preferred embodiment, a device is made of PE, having a density of 1 kg/l. The diameter of the inner chamber is ca 40 cm, and a weight being attached to the device as shown in the figures, has an inner diameter of ca 35 cm. The ballast of the weight is 55 kg concrete, giving the device a weight under water of ca 55 kg.

The examples above are given to illustrate the invention, and should not be used to interpret the following claims in a limited manner. The scope of the invention is not limited by the examples given above, but by the following claims. Modifications and amendments of the invention, being obvious to a skilled person, should also be included in the scope of the invention.

Claims

1. Device for distribution of a liquid to a volume of water and to prevent a fish net from entangling in a pipe removing fish and water, the device comprises a wall (1) surrounding an inner chamber (2), and separating the chamber (2) from the outer environment of the device, characterized in that

- an inlet (3) to the inner chamber (2) is arranged in the wall (1),

- a number of outlets (4) from the inner chamber (2) is arranged in the wall (1), wherein the outlets (4) are distributed on an outer surface of the device, and in that - the device further comprises a ballast (5) increasing the total weight of the device under water, to more than 10 kg.

2. Device according to claim 1, characterized in that the total weight of the device under water is more than 50 kg.

3. Device according to claim 1 or 2, characterized in that the inner chamber (2) is shaped as a ball.

4. Device according to any one of claims 1 - 3 , characterized in that the device comprises a connection element configured to be attached to a weight (5).

5. Device according to any one of claims 1 - 4, wherein the inlet (3) is arranged to be attached to a pipe for supply of water enriched in oxygen.

6. Device according to any of the preceding claims, wherein the connection element is arranged on a side opposite to the inlet (3) of the device.

7. Device according to any of the preceding claims, wherein a passage (9) to accommodate a shaft (11) is arranged through the center of the chamber (2), the passage is defined by walls (10) separating the inner chamber (2) from the passage (9).

8. Device according to claim 6, wherein the connection element is a shaft (11) accommodated in the passage (9).

9. Device according to any of the preceding claims, wherein the weight (5) is a ball with an inner chamber (6) filled with ballast material (7) such as concrete or metal.

10. Method for distributing water enriched in oxygen to a volume of water by using a device according to the claims 1- 9 above, characterized by the following steps i) connecting a tube to the inlet (3) of the device,

ii) lowering the device into the volume to be oxygenated,

iii) adding oxygenated water into the tube.

11. Method according to claim 10, further comprising a step for attaching a weight (5) to the connection element before step i) or ii).