EP3968766A1

EP3968766A1 - Method and device for the oxygen enrichment of water in a pisciculture installation

Info

Publication number: EP3968766A1
Application number: EP20721185.5A
Authority: EP
Inventors: Atanas RISTOV
Original assignee: Messer Bulgaria EOOD
Current assignee: Messer Bulgaria EOOD
Priority date: 2019-05-11
Filing date: 2020-04-21
Publication date: 2022-03-23
Also published as: DE102019003346B3; WO2020229106A1

Abstract

The invention relates to a method and a device (5) for the oxygen enrichment of water in a pisciculture installation (1), in which a fish stock is held in a net enclosure (3) within a body of water (2). It is proposed, according to the invention, that air is supplied into a vertical pipe (6) for conveying water from deeper layers of the body of water to the region of the surface, and in addition oxygen is injected in the region of the lower mouth opening (11) of the pipe. The oxygen dissolves to a large extent in the water and thus leads to oxygen enrichment of the conveyed water. The oxygen-enriched water is returned to the body of water in the region of the water surface (9) above the net enclosure.

Description

Method and device for the oxygenation of water

in a fish farm

The invention relates to a method for the oxygen enrichment of water in a fish farm, in which a fish population is kept in a net enclosure within a body of water and water is conveyed from a deeper layer of the body of water into the area of the water surface, above the net enclosure, by water being fed into a lower opening a pipe running upwards at least in sections within the body of water flows in, the water flowing into the pipe is mixed with air supplied above the lower mouth opening, but below the surface of the water, thereby generating an upward flow in the pipe.

The invention also relates to a device with a

Oxygen enrichment equipped fish farm with one in one

Net enclosures arranged in water bodies.

In standing water, depending on the climatic conditions of the environment, a horizontal stratification is formed, which is characterized by zones of different temperatures and oxygen concentrations. A typical one

The stratification of a lake has a near-surface layer (epilimnion) in summer, which ends about 4-6m below the water surface and due to a strong thermal and material exchange with the surrounding atmosphere

is marked. A transition layer follows the epilimnion

(Metalimnion) in which with increasing depth temperature and

Significantly decrease oxygen concentration. Below the Metalimnion is the deep water layer (hypolimnion) from a depth of approx. 8-10 m with an essentially constant temperature of approx. 4 ° C all year round and a very low oxygen content of max. 4-5 mg / l.

The breeding of freshwater fish in aquaculture usually takes place in specially created fish ponds or flow channels. More intensive fish farming allows the use of net pens or fish cages, which are located in larger freshwater waters,

for example for breeding trout, or in the open sea for breeding Sea fish such as salmon can be placed. Net pens usually have a diameter between 4 and 60 m and a depth between 4 and 10 m. The present invention relates to fish breeding systems with net cages or fish cages which are arranged within a body of water, for example in a freshwater lake or in the sea.

The natural entry of oxygen into stagnant water takes place on the one hand on the water surface by diffusion from the air and on the other hand through

Photosynthesis of aquatic plants. The solubility of oxygen in water decreases with increasing temperature. Flea ambient temperatures lead to a lack of oxygen in the water, which affects the health of the fish and slows their growth. In such cases, artificial ventilation is essential

Fish farm required.

For the ventilation of fish ponds, aeration systems are currently used in particular, in which water from deeper water layers is transported to the surface by means of an electric pump, where it mixes with ambient air. Paddle wheel aerators are also used, in which the surface water is circulated and brought into contact with the ambient air. Deep aerators are also used, in particular for the restoration of stagnant water, in which air is fed directly into deeper ones by means of a compressor

Water layers is entered. The disadvantage of these systems, however, is a high expenditure and a comparatively low degree of efficiency.

DE 20 2018 001 727 U1 describes a device for circulating and

Aerating bodies of water, in particular fish ponds. The one described there

The device comprises a flow pump working according to the air lift principle (mammoth pump principle), in which an air-water mixture is generated at the bottom in a pipeline that extends to the bottom of the body of water, which is then passed through a pipe section that runs obliquely upwards and is still below the Water surface leaks. In this way a strong current is created to circulate and aerate the water. However, the device is only smaller for ventilation, and above all with a maximum depth of about 1.5m shallower, suitable for water. In addition, it requires the use of complex electrical pump arrangements for supplying the air.

US 6 017 020 B1 describes a system for introducing air into a lake. The entry system comprises two coaxially arranged and deep inside

Pipes several meters long, embedded in the lake bottom, which are connected to each other at their lower end. Also at the lower end is a device for introducing air into the inner tube. When the device is in use, water flows through the outer tube into the inner tube, where it is enriched with air and rises upwards due to the mammoth pump effect. Due to the submarine arrangement, however, the entry system is very complex to install and maintain. Not least for this reason, this system is only suitable for the aeration of shallow water, for example 1.5 m deep, and thus not for fish farming systems that are equipped with net cages.

The invention is therefore based on the object of creating the simple and reliable oxygenation of water in fish farming systems which are equipped with net cages or fish farming cages in bodies of water.

This problem is solved by a method with the features of

Claim 1 and by a device with the features of

Patent claim 6. Advantageous embodiments of the invention are in the

Subclaims indicated.

A method according to the invention for the oxygen enrichment of water in a fish farming system of the type and purpose mentioned at the beginning is

according to the invention, characterized in that the water flowing into the pipeline is supplied with oxygen from an oxygen source at an injection device opening into the pipeline in the region of the lower mouth opening.

An oxygen-containing gas with an oxygen content of over 90% by volume, preferably over 95% by volume, is to be referred to here as “oxygen”. At the source for Oxygen (also called “oxygen source” here) is, for example, an oxygen tank, a pressurized gas cylinder or a bundle of pressurized gas cylinders.

According to the invention, on the one hand, by supplying a strong air flow according to the mammoth pump effect, a strong, upward flow is generated in the pipeline, which means that the water flowing in at the lower mouth opening is conveyed from deeper layers of the water into the area of the water surface and on an upper mouth of the pipeline flows out, which opens above the net enclosure. The upper mouth of the pipeline can be completely or partially above or below the water surface. The air is supplied primarily to generate the flow within the pipeline and can take place in a comparatively near-surface area, for example 1 -3 m below the water surface. In addition to the entry of air, there is also an entry of oxygen. This takes place in a region of the pipeline which, when the method is used, is arranged below the air supply, preferably close to the lower mouth of the pipeline. For example, the oxygen injection device is located a few meters on the pipeline,

for example 3-10 m, below the height of the air intake. The suction effect of the air intake is sufficient to be able to suck in water from such deep layers of the water into the pipeline; So it is not necessary to generate the upward flow, the air with a corresponding effort deep down, for example in the area of the lower mouth opening in the

Enter the pipeline. On the other hand, the oxygen carried further below into the water runs a comparatively long distance in the pipeline, whereby it partially dissolves in the water.

The procedure according to the invention enables the pumping of comparatively cold and oxygen-poor water from deeper water layers, into which the supplied oxygen can be readily dissolved. A comparatively small amount of oxygen supplied, for example 1 to 5 l / min, is sufficient to enrich the supplied water with oxygen by for example 3-10 mg / l with a water inflow via the pipeline of, for example, 5-20 l / s effect. In contrast, only a comparatively small part of the entrained air in the water of the pipeline, whereby the nitrogen content in the water increases only slightly. The flow rate of the supplied oxygen is also significantly less than the flow rate of the supplied air, which is 50-100 l / min, for example, and in contrast to this, contributes to

Promotion of the water through the pipeline only insignificantly.

With the method according to the invention, the near-surface water in the net enclosure is cooled in summer operation by the supply of cooler water from deeper layers of the body of water. In winter, however, the comparatively warm water from the deeper layers prevents the from freezing

Body of water. The inventive method is particularly suitable for

Fish farms that are set up in freshwater lakes, for example in larger natural lakes or in reservoirs; however, it is also suitable for marine aquaculture.

In order to further improve the dissolution of the oxygen in the water guided through the pipeline, the injection device is preferably designed in such a way that ambient water is introduced into the pipeline simultaneously with the oxygen. An intimate mixing of water and oxygen takes place already within the injection device. This is done, for example, in that the oxygen supply to the injection device is in the manner of a

Venturi nozzle is formed and by the flow of oxygen introduced from the oxygen source at high pressure into the injection device, surrounding water is sucked from the water into the injection device and mixed with the oxygen.

The oxygen is according to the invention with an overpressure of preferably at least 3 bar, particularly preferably at least 5 bar compared to the

surrounding water pressure entered into the pipeline and / or into the injection device. The generation of the upward flow in the

Air supplied to the pipeline is introduced into the pipeline at an overpressure of, for example, 0.2 bar to 1 bar compared to the surrounding water pressure.

In another advantageous embodiment of the method according to the invention, the lower mouth opening of the pipeline opens into the deep water of the Water, so cold deep water is enriched with oxygen and conveyed through the pipeline to the net enclosure.

“Deep water” is used here to describe water that is low in oxygen and at a temperature of around 4 ° C, which is far below the surface, preferably at a depth of more than 10 m below the surface of the water. In the case of freshwater bodies of water, it is intended to denote water that is located in the area of the hypolimnion. Due to its low temperature and its low oxygen content, deep water has a compared to the closer to

Layers of water lying on the surface of the water have a much higher capacity for dissolving oxygen.

The object of the invention is also achieved with a fish farming system having the features of claim 6.

A fish farming system that is equipped with a net enclosure (also known as a "fish cage") arranged in a body of water and with a device for oxygen enrichment, and in which the device for oxygen enrichment comprises a pipeline running upwards at least in sections and with a lower opening into the water immersed in the spaced from the lower mouth opening a feed for compressed air into the pipeline, is characterized according to the invention in that on the pipeline in the area of the lower mouth opening via an oxygen feed line with a

Oxygen source connected injection device for supplying oxygen is arranged in the pipeline.

As a "partially upwardly running pipeline" a pipeline is to be understood, which has at least one geodetically from bottom to top, for example vertically or obliquely, in which an upward flow can be generated by the supply of air after the mammoth pump effect. The lower mouth is preferably immersed in a layer of the water that is deeper than the bottom (ie the lower boundary) of the net enclosure. For example, the lower mouth extends into the flypolimnion of the water. The pipeline opens into an upper one The mouth of the pipeline, above or below the surface of the water, but above the net enclosure. The injection device through which, in addition to compressed air, oxygen is introduced into the water guided through the pipeline, is arranged on the pipeline at a distance below the feed for compressed air, in particular in the area of the lower mouth opening.

The upward section of the pipeline connects to - in

Seen flow direction - preferably a substantially parallel to

Section of the water surface running or curved downwards

Pipeline which ends at the upper mouth opening of the pipeline, the upper mouth opening is thus arranged offset in the horizontal direction with respect to the lower mouth opening. This means that the pumped water can be directed specifically into the area of the water surface above the net enclosure, at the same time this arrangement ensures that the pumped water does not come from the area directly below the net enclosure, which could be contaminated with waste products from the metabolism of the fish.

An advantageous embodiment of the device according to the invention is characterized in that the lower mouth of the pipeline opens out at a depth of at least 5 m, preferably at least 12 m below the water surface, in the latter case in the deep water of the body of water.

The feed for compressed air preferably opens into the pipeline at a depth of at most 5 m, preferably at most 2 m below the water surface of the body of water. As a result, a comparatively weak pump can be used to supply the air, which, for example, can also be supplied with electricity from a solar-powered unit installed on site. The flow created in this way by the introduction of the air in an upper area of the pipeline through the mammoth pump effect is sufficient to convey the water from deeper layers of the water through the pipeline.

In order to enable an intimate mixing of water and oxygen within the injection device, an advantageous development of the invention provides that the injection device comprises a mixing chamber into which one Feed nozzle for oxygen and at least one feed opening for water opens and which has an outlet for a water-oxygen mixture which is flow-connected to the pipeline.

The mixing chamber can be designed so that all of the water conveyed through the pipeline runs through the injection device, which forms at least one feed opening for the water, i.e. the lower opening of the pipeline, or in such a way that only a partial flow of the water into the pipeline

Inflowing water is passed over the injection device and mixed with the oxygen introduced there.

In particular, the supply nozzle for the oxygen can be designed as a Venturi nozzle, by means of which a strong flow of the introduced oxygen is achieved in the injection device, which is sufficient to circulate the surrounding water through the

To suck in feed openings for the water into the injection device.

An exemplary embodiment of the invention will be explained in more detail with the aid of the drawing. The single drawing shows schematically an inventive

Fish farm.

The fish breeding system 1 shown in FIG. 1 comprises a net enclosure 3 arranged within a body of water 2, for example a lake, for receiving a fish population (not shown here) and a device 5 for oxygenation.

The device 5 comprises a substantially L-shaped pipe 6 with a first pipe section 7, which in the embodiment shown here in

Immersed essentially vertically in the body of water 2 and a second

Pipeline section 8, which runs essentially on fleas of the water surface 9 of the body of water 2 and parallel to it and opens out above the net enclosure 3 at an upper mouth opening 10 of the pipeline 6. The

The pipe section 8 can also be curved downwards and / or formed with an opening 10 pointing downwards. The pipe section 7 opens with a lower mouth opening 11 in a deeper layer of the body of water 2. The length of the pipe section 7 is chosen, for example, so that the lower mouth opening 11 protrudes into the deep water (hypolimnion) of the body of water 2, i.e. a low-oxygen and comparatively cold (approx. 4 ° C) water layer, but the invention is not limited to this. For example, the mouth opening 11 opens out approximately between 5 m and 12 m below the water surface 9 of the body of water 2. The net enclosure 3 is located in a water layer above the hypolimnion and extends, for example, to a depth of 4-10 m below the water surface 9, but preferably not as deep as the lower mouth opening 11 of the pipeline 6.

In the area of the lower mouth opening 1 1 of the pipeline 6 is a

Injection device 12 arranged for supplying oxygen. The

Injection device 12 is flow-connected to a source 14 for oxygen via an oxygen supply line 13. For example, the source 14 is a pressurized gas cylinder or a bundle of pressurized gas cylinders in which oxygen with a purity of 95% by volume is stored under pressure, for example 200 bar or 300 bar. In order to be able to set the pressure in the oxygen supply line 13 to a predetermined operating pressure, the oxygen supply line 13 has a

Pressure reducer 15 arranged.

The injection device 12 comprises a mixing chamber 16 into which an oxygen nozzle 17, which is connected to the oxygen supply line 13, opens centrally. A number of water inlets 18 are arranged radially to this in preferably equal angular sections. Furthermore, the mixing chamber 16 has an outlet 19, which is flow-connected to the pipeline 2, for the water-oxygen mixture that is formed in the mixing chamber 16.

In the pipe section 7, above the injection device 12, but below the water surface 9, for example between 1 m and 3 m below, an entry system 21 for air is arranged. The entry system 21 comprises a perforated pipe section 22 in the pipeline 6, which is encased radially on the outside by a pipe section 24 while maintaining an annular gap 23. The pipe section 24 is at both ends above and below the perforated pipe section 22 connected to the pipeline 6 in a watertight manner. An air supply line 25 which is connected to an air pump 26 opens into the annular gap 23. The air pump 26 is preferably driven electrically.

When the device 5 is in operation, air is fed into the pipeline 6 by means of the air pump 26 via the air supply line 25 and the entry system 21 under an overpressure of, for example, 0.3 bar. The resulting mixture of water and air has a significantly lower density than the surrounding water in the pipeline 6, whereby a strong, upward flow is generated within the pipeline section 7 (mammoth pump effect). The mixture of water and air passes through the pipe sections 7 and 8 and flows on the

Muzzle opening 10 from the pipeline 6. From there it sinks into the area of the net enclosure 3 due to its lower temperature compared to surface water.

The water sucked in due to the mammoth pump effect at the lower mouth opening 11 of the pipeline 6 is transferred to the injection device 12

Oxygen enriched. For this purpose, oxygen is introduced from the oxygen source 14 via the oxygen supply line 13 into the mixing chamber 16, where it is intimately mixed with water which flows into the mixing chamber 16 through the water supply lines 18. The mixture of water and oxygen enters the pipeline 6 and is entrained with the flow of the rest of the water supplied via the orifice 11. Due to the intensive mixing of the oxygen with the water and the comparatively long common flow path, a considerable part of the oxygen is dissolved in the water. The water exiting at the mouth opening 10 is therefore highly enriched with oxygen and has a proportion of dissolved oxygen which is, for example, 5-7 mg / l above the oxygen content of the water flowing in at the mouth opening 11. Reference list

1 fish farm

2 bodies of water

3 net pens

4th

5 device

6 pipeline

7 pipe section

8 pipe section

9 water surface

10 Upper mouth opening

11 Lower mouth opening

12 injection device

13 Oxygen supply line

14 source of oxygen

15 pressure reducers

16 mixing chamber

17 oxygen nozzle

18 Water supply

19 diversion

20th

21 Entry system for air

22 perforated pipe section

23 annular gap

24 pipe section

25 air supply

26 air pump

Claims

1. Method for oxygenation of water in a fish farm, in which a fish population is kept in a net enclosure (3) within a body of water (2) and water from a deeper layer of the body of water (2) into the area of the water surface (9), above the net enclosure (3), is promoted by water flowing into a lower mouth opening (1 1) of a pipe (6) running upwards at least in sections within the body of water, but the water flowing into the pipe (6) above the lower mouth opening (1 1) air supplied below the water surface (9) is mixed and an upward flow is generated in the pipeline (6),

characterized,

that the water flowing through the pipeline (6) is supplied with oxygen from an oxygen source (14) at an injection device (12) opening into the pipeline (6) in the area of the lower mouth opening (11).

2. The method according to claim 1, characterized in that on the

Injection device (12) a mixture of water and oxygen is fed into the pipe (6).

3. The method according to claim 2, characterized in that in the

Injection device (12) oxygen is entered and due to the flow generated thereby water from the body of water (2) is sucked into the injection device (12).

4. The method according to any one of the preceding claims, characterized

characterized in that the oxygen with an excess pressure of at least 3 bar, preferably at least 5 bar in the pipeline (6) and / or in the

Injection device (12) is entered.

5. The method according to any one of the preceding claims, characterized in that through the pipeline (6) deep water of the body of water

(2) is funded.

6. Fish farm, with a net enclosure arranged in a body of water (2)

(3) and with a device (5) for oxygen enrichment, wherein the

The device (5) for oxygen enrichment comprises a pipe (6) which runs upwards at least in sections and which is connected to a lower

The mouth opening (1 1) is immersed in the body of water (2) and at a distance from the lower mouth opening (1 1) a feed (21) for compressed air opens into the pipeline (6),

characterized,

that on the pipeline (6), below the feed (21) for compressed air, an oxygen feed line (13) with an oxygen source (14)

flow-connected injection device (12) for supplying oxygen into the pipeline (6) is arranged.

7. Fish farming system according to claim 6, characterized in that the lower mouth opening (1 1) of the pipeline (6) opens out at a depth of at least 5m, preferably at least 12m below the water surface (9) of the body of water (2).

8. Fish farming system according to claim 6 or 7, characterized in that the feed (21) for compressed air opens into the pipeline (6) at a depth of a maximum of 5 m, preferably a maximum of 2 m below the water surface (9) of the body of water (2).

9. Fish farming system according to one of claims 6 to 8, characterized in that the injection device (12) comprises a mixing chamber (16) into which a feed nozzle (17) for oxygen and at least one feed opening (18) for water open out, and via a discharge line (19) for a water-oxygen mixture is flow-connected to the pipeline (6).