NO347921B1

NO347921B1 - Fish flow control system and method of controlling a biomass mass flow in the system

Info

Publication number: NO347921B1
Application number: NO20220043A
Authority: NO
Inventors: Kristian Lillerud; Frank Rånes
Original assignee: Flatsetsund Eng As
Priority date: 2022-01-12
Filing date: 2022-01-12
Publication date: 2024-05-13
Also published as: NO20220043A1

Description

Within the field of fish-farming, it is sometimes necessary to transport fish both to move fish from one location to another, to locate the fish in a system for treating the fish in one way or another or for monitoring or sorting the fish. Waterflow in ducts entrain the fish.

When treating fish in a treatment chamber, is fish pumped from a first confined body of water into a chamber where it is treated and then into a second confined body of water. The first and the second body of water are typically confined with a net / a pen, and the treatment is typically delousing for removal of parasites such as salmon lice.

Mechanical delousing of fish is generally performed in ducts with dimensions around 250 to 300 mm in diameter. The relatively small duct diameters are largely used in order to prevent multiple fish from being transported through the pipe simultaneously, thus preventing overlap and making the distance from the pipe wall to the fish relatively short and predictable. Injecting and withdrawing water can be done evenly around the fish without affecting its position, making it possible to use water nozzles to clean and delouse fish using relatively low water pressures.

A problem when transporting fish in ducts such as pipes is however that the duct may get too crowded or congested, resulting in an overlap of fish and this may cause a flow restriction and thus reduced water flow, reduced fish welfare, increased stress for the fish and even fish injuries. The ejector driving the water flow is particularly vulnerable for congestion of high density of fish. The mass flow of fish is typically 50-60 tons/hr and it is an aim with the invention to provide a system and a method allowing a steady high flow of fish without risking clogging of the ducts due to intermittent flow resulting in the above-mentioned problems.

WO 2020/226505 discloses a method and system for fully automatic transportation of alive fish from a water-filled fish reservoir or storage container to a processing station transportation or receiving reservoir or storage container providing an even flow of alive fish delivered to the processing station or receiving reservoir or storage container at any time.

NO 314481 discloses an apparatus for sorting marine objects in a fish pen etc. It includes a flow path for moving the objects between two volumes of water. A sorting grid in a chamber enclosed in a mass of water with controlled, directed water flow is provided in the flow path.

An aim of the invention is also to provide a system and a method allowing a steady high flow of fish automatically and without operator intervention, based on control parameters provided by a fish counter, and in some cases also one or several pressure sensors.

The present invention relates to a fish flow control system for a live fish transport system. Live fish transport systems are used for treatment of fish such as delousing, and live fish transport systems typically include one or several fish treatment stations.

The present invention relates to a fish flow control system for a live fish transport system. The fish flow control system including a fluid path for water and live fish. The fluid path includes a fish inlet duct section adapted suck in fish and water from a body of water, an intermediate transport duct section, a fish counter, an ejector and an exit duct section. A bypass inlet in fluid connection with a bypass valve for fluid connection with a source of water, is located between the fish inlet duct section and the intermediate transport duct section. The ejector forms a water flow inducing element inducing water flow in the fluid path for water and live fish. An ejector pump in fluid connection with the ejector is adapted to provide motive water to an ejector inlet duct. A fish flow control unit is adapted to receive information from the fish counter in relation to the biomass mass flow / flowrate of biomass past the fish counter, and to provide a signal to control the bypass valve in response to the biomass mass flow past the fish counter. The fish flow control unit is furthermore adapted to receive information from a flowrate sensor adapted to output a signal in relation to the flowrate of water in the intermediate transport duct section, and to output a signal to control a flowrate of water into the ejector motive fluid duct (26) in response to the signal (13) from the flowrate sensor.

The fish flow control system may further include a water velocity sensor in the fluid path for water and live fish, downstream of the bypass inlet.

. The fish flow control system typically seeks to keep the water velocity in the intermediate transport duct section constant.

The flowrate sensor may form a part of the fish counter.

The fish flow control system may further include a distribution valve adapted to distribute water between the flow path between the water pump, the ejector, and a bleed duct, whereby the distribution valve is adapted to control the flowrate of water into the ejector.

The fish flow control system may further include a pump flowrate control unit, adapted to control the flow rate into the ejector.

The fish flow control unit may be adapted to control at least one of the pump flowrate control unit and the distribution valve.

The fish flow control system may further include a pressure sensor in the ejector motive fluid duct adapted to output a pressure sensor signal to the fish flow control unit.

An inlet of the bypass valve may be in fluid connection with a return duct section for water returning from the exit duct section.

The fish counter may be located in the intermediate transport duct section between the bypass inlet and the ejector..

The fish flow control system may further include a filter between the bleed duct from the distribution valve and an inlet channel to the bypass valve.

Furthermore, the present invention relates to a method of controlling a biomass mass flow in a live fish transport system including a fluid path for water and live fish. The fluid path includes a fish inlet duct section adapted suck in fish and water from a body of water, an intermediate transport duct section, a fish counter. The live fish transport system further includes an ejector and an exit duct section. The method includes the following steps: monitoring biomass mass flow with the fish counter, outputting a fish counter biomass mass flow signal, receiving the fish counter biomass mass flow signal with a fish flow control unit, and

outputting a bypass valve control signal from the fish flow control unit in response to the fish counter biomass mass flow signal, receiving the bypass valve control signal with the bypass valve to control the bypass valve in response to the monitored biomass mass flow to increase the flow through the bypass valve when the biomass mass flow exceeds a set limit.

The method of controlling the biomass mass flow / flowrate of biomass in the live fish transport as described above may further include providing a water velocity signal from a water velocity sensor, providing an ejector pressure signal from an ejector pressure sensor in a ejector motive water inlet duct, receiving the water velocity signal and the ejector pressure signal with the fish flow control unit, outputting a flowrate signal to control the flowrate of motive water for the ejector by controlling at least one of a distribution valve, allowing a bleed off from an injector pump, pumping the ejector motive fluid and a pump control unit of the ejector pump..

The water velocity sensor may be the fish counter.

Brief description of the enclosed figures:

Fig. 1 is a schematic representation of a fish flow system of the invention; and Fig. 2 is a schematic representation of an alternative embodiment of a fish flow system of the invention.

Detailed description of an embodiment of the invention with reference to the enclosed figures:

Fig. 1 a schematic representation of a fish flow system 1 of the invention. The fish flow system 1 includes a fish flow control unit 10 receiving signals from the fish flow system 1 and that controls the waterflow and fish flow through the system. The aim of the system is to avoid a too high density of fish in the ducts and the components carrying the fish and water. The fish flow control unit 10 controls a bypass valve 8 providing water to a bypass inlet 2. The bypass valve 8 includes a valve actuator allowing the flow rate through the bypass valve 8 to be controlled with a bypass valve control signal 11. An inlet duct section 20 for fish and water includes an inlet opening located in a first pen containing the fish and extends into the bypass inlet 2 and from there into a first intermediate transport duct section 21 and into a fish counter 3. A second intermediate transport duct section 22 extends between the fish counter 3 and an ejector 4. An exit duct section 23 extends into a second pen containing fish and includes an outlet for water and fish. The duct sections and the elements are sealed to allow the water at the inlet side to balance the water at the outlet side to reduce the required pumping power.

The bypass inlet 2 typically includes a portion of pipe with inlet ports surrounding the pipe to ensure transport of fish while maintaining a position of the fish at the centre of the pipe.

As explained above, the fish enters through the entrance of the inlet duct section 20. The inlet duct section 20 is curved from an upwards directed portion and to a substantially horizontal portion and, and the amount of fish entrained in the water flowing through the inlet duct section 20 is partly dependent on the mass flow of water through the inlet duct section 20. The flowrate of the water entering the bypass inlet 2, controlled by bypass valve 8, also controls the flow rate through the inlet duct section 20, as the flow rate through the first intermediate transport duct section 21 is the sum of the flowrate of the water entering the bypass inlet 2 and the flowrate through inlet duct section 20. It is an aim to keep this sum constant. The bypass valve 8 thus contributes to control the flow rate through the inlet duct section 20 and the amount of fish entrained through the system. The water to the bypass valve 8 may be taken from a drum filter 7 or any other source of preferably uncontaminated water. The pressure at the bypass inlet 2 is lower than the atmospheric pressure and no additional pump is needed to allow water into the bypass valve 8. The lines 29 crossing the bleed duct to the bypass valve 8 indicates that the water to the bypass valve 8 not necessarily is taken from the drum filter 7, and that the flow through the bleed duct 27 to a filter 7 not necessarily is proportional to the flow through the bypass valve 8.

A return pipe 24 into the inlet of pump 25 is shown with interrupting lines 29 crossing the return pipe 24 to indicate that water to the pump not necessarily is taken from the return water.

The first intermediate transport duct section 21 enters the fish counter 3 providing information about the biomass mass flow rate and the water velocity. Other data that may be provided by the fish counter 3 are number, size and velocity of the fish. The fish counter 3 thus output information in relation to how congested or crowded the duct sections are.

Congested duct sections may as noted partly block the for waterflow, may reduce the fish welfare and may even stress or harm the fish.

The second intermediate transport duct section 22 extend from the fish counter 3 and to the ejector 4 providing the water flow. The ejector 4 is particularly vulnerable for congestion and a distribution valve 6 controls the amount of motive water received by the ejector 4 from a water pump 8 to prevent pressure loss over the ejector 3. The distribution valve 6 distributes water between an ejector motive water inlet pipe 26 for the ejector 4 and the bleed duct 27 extending to a drum filter 7 for parasites before the water is allowed to re-enter the fish flow system 1 as needed through the inlet duct 28 to bypass valve 8. The distribution valve is controlled by the fish flow control unit 10. The amount of water entering the ejector 3 also controls the flow rate through the system to control the flow of fish.

The fish flow control unit 10 receives fish counter fish mass/biomass mass flow input signal 12 and water velocity input signal 13 from the fish counter and an ejector motive water pressure input signal 14 from the ejector pressure sensor 16 at the inlet from the ejector pump 5.

The fish flow control unit 10 provides a bypass valve control signal 11 to control the bypass valve 8, and a distribution valve control signal 15 to control the distribution valve 6 and/or a pump flowrate control unit 30 controlling pumped flow rate.

Water to the ejector pump 5 is taken from a return pipe 24 from an exit flow suction unit (not shown) at the outlet of the exit duct 23, collecting outlet water and waste from the outlet of the exit pipe 24.

The flowrates through the various parts of the fish flow system 1 can thus be controlled by the fish flow control unit 10, controlling the bypass valve 8 and the distribution valve 6, based on input from the fish counter 3 and the ejector pressure sensor 16.

The ejector pump 5 typically operates at constant speed / flow rate and the control unit 10 is programmed to increase the flowrate through the ejector 4 when water velocity through the fish counter 3 decreases. The amount of water through the bypass inlet 2 is increased to decrease the flow rate through the inlet duct section 20 and thus to decrease the amount of fish that is drawn into the system.

The pump flowrate control unit 30 controlling the flow rate through the ejector pump 5, may be used in addition to or in place of the distribution valve 6 to control the ejector motive fluid.

The features of the fish counter 3 may be divided into separate elements and a separate biomass flow sensor 31 may be located in the inlet duct section in addition to, or in place of a biomass flow sensor in the fish counter 3.

An optimized flow of fish is typically 50-60 tons/hr, and a typical diameter of the ducts is 400mm and 250mm.

Fig. 1 shows various elements that not necessarily needs to be used together. A pump flowrate control unit 30 is typically not needed in systems with the distribution valve 6 as these elements serves the same purpose of controlling the motive water flow into the ejector. Similarly, is biomass mass flow sensor 31 needed if the fish counter 3 serves the same purpose etc.

Fig. 2 shows an alternative embodiment of the invention. The water flow inducing element is a fish pump 40 located downstream of the bypass inlet 2 receiving water from the bypass valve 8 and upstream of the fish counter 3. A fish treatment station 41 is located downstream of the fish counter, and a lice removal section 42 is located downstream of the fish treatment station 41. The drum filter 7 collects water and salmon lice from the lice removal section 42. The delousing facility 42 and the drum filter 7 may be provided as a separate delousing facility 43. The bypass valve receives a bypass valve control signal 11 from the fish flow control unit 10 based on the biomass mass flow signal from the fish counter 3. The fish pump 40 receives a fish pump control signal from the fish flow control unit 10 based on the water velocity signal 13 from the fish counter 3. The fish pump control signal controls the flow rathe through the fish pump 40. A fish pump control unit 44 controls the fish pump 40 based on input from the fish flow control unit. The fish treatment station 41 may be a delousing station and the lice removal section 42 can then remove lice entrained in the waterflow from the fish treatment station 41.

The different components and solutions shown in the embodiments of fig.1 and fig. 2 may be combined if the flow of the inlet duct section 20 is controlled by the bypass valve 8 allowing water to bypass the inlet duct 20 whole the flow in the intermediate transport duct section is maintained.

Claims

1. A fish flow control system for a live fish transport system including a fluid path for water and live fish, the fluid path including an inlet duct section (20) adapted to entrain life fish in a flow of water to transport the fish from a body of water, an intermediate transport duct section (21), and an exit duct section (23), the fish flow control system further including a bypass inlet (2) in fluid connection with a bypass valve (8) for fluid connection with a source of water, located between the fish inlet duct section (20) and the intermediate transport duct section (21),

c h a r a c t e r i s e d i n:

an ejector (4) forming a water flow inducing element inducing water flow in the fluid path for water and live fish;

an ejector pump (5) in fluid connection with the ejector (4) adapted to provide motive water to an ejector inlet duct (26);

a fish flow control unit (10) adapted to receive information from a fish counter (3) in relation to a biomass mass flow past the fish counter (3), to output a signal to control the bypass valve (8) in response to the biomass mass flow, to receive information from a flowrate sensor adapted to output a signal in relation to the flowrate of water in the intermediate transport duct section (21), and to output a signal to control a flowrate of water into the ejector motive fluid duct (26) in response to the signal from the flowrate sensor.

2. The fish flow control system of claim 1, further including a water velocity sensor in the fluid path for water and live fish, downstream of the bypass inlet (2).

3. The fish flow control system of claim 1 or 2, wherein the flowrate sensor is a part of the fish counter (3).

4. The fish flow control system of any of the preceding claims, further including a distribution valve (6), adapted to distribute water between the flow path between the ejector pump (5) and the ejector (4) and a bleed duct (27), whereby the distribution valve (6) is adapted to control the flowrate of water into the ejector (4).

5. The fish flow control system of any of the preceding claims further including a pump flowrate control unit (30), adapted to control the flow rate into the ejector (4).

6. The fish flow control system of any of the preceding claims, wherein the fish flow control unit (10) is adapted to control at least one of the pump flowrate control unit (30) and the distribution valve (6).

7. The fish flow control system of any of the preceding claims, further including a pressure sensor (16) in the ejector motive fluid duct (26) adapted to output a pressure sensor signal (14) to the fish flow control unit (10).

8. The fish flow control system of any of the preceding claims, wherein an inlet of the bypass valve (8) is in fluid connection with a return duct section (24) for water returning from the exit duct section (23).

9. The fish flow control system of any of the preceding claims, wherein the fish counter (3) is located in the intermediate transport duct section (21, 22) between the bypass inlet (2) and the ejector (4).

10. The fish flow control system of claim 4, further including a filter (7) between the bleed duct (27) from the distribution valve (6) and an inlet channel to the bypass valve (8).

11. A method of controlling the biomass mass flow in a live fish transport system including a water path for water and live fish, the water path including a fish inlet duct section (20), adapted suck in fish and water from a body of water, an intermediate transport duct section (21) and a fish counter (3),

c h a r a c t e r i s e d i n:

that the live fish transport system further includes an ejector (4) and an exit duct section (23), the method comprising the steps of:

monitoring a biomass mass flow with the fish counter (3);

outputting a fish counter biomass mass flow signal (12);

receiving the fish counter biomass flow signal (12) with a fish flow control unit (10); outputting a bypass valve control signal (11) from the fish flow control unit (10) in response to the fish counter biomass mass flow signal (12);

receiving the bypass valve control signal (11) with the bypass valve (8) to control the bypass valve in response to the monitored biomass mass flow to increase the flow through the bypass valve (8) when the biomass mass flow exceeds a set limit.

12. The method of controlling the biomass mass flow in a live fish transport system of claim 11, further including:

outputting a water velocity signal (13) from a water velocity sensor;

outputting an ejector pressure signal (14) from an ejector pressure sensor (16) in an ejector motive water inlet duct (26);

receiving the water velocity signal (13) and the ejector pressure signal (14) with the fish flow control unit (10);

outputting a signal from the fish flow control unit (10) controlling the flowrate of the motive water for the ejector by controlling at least one of a distribution valve (6), allowing a bleed off from an ejector pump (5) pumping the ejector motive water, and a pump control unit (30) of the ejector pump (5).

13. The method of controlling the biomass mass flow of claim 11, wherein the water velocity sensor is the fish counter (3).