Device for transporting aquatic animals

Abstract

A device 131 with a primary conduit 133 for transporting aquatic animals in a flow liquid in a first direction 135 from a first end 137 to a second end 139, and a secondary inlet 141, 143 that is positioned between the ends of the primary conduit, so that pump liquid from the secondary inlet functions as an ejector pump. The secondary inlet introduces a flow of pump liquid in proximity to an internal curved surface of the primary conduit. There may be a guard 145 to keep objects in flow liquid away from the internal surface of the primary conduit. The guard may be in a position downstream of the secondary inlet 144. The guard may be made of elongate members 147 such as wires coupled to the inner wall of the primary conduit. The secondary inlet may be concentric to the primary conduit.

Description

Field of Invention The present invention relates to a device for transporting aquatic animals and in particular for transporting live fish. Background of the Invention Fish farming is a type of aquaculture, which is the controlled cultivation and harvesting of aquatic animals such as fish, crustaceans, molluscs and so on, in natural or pseudo-natural environments. Global demand for dietary fish protein has increased, which has resulted in widespread overfishing in wild fisheries, resulting in significant decrease in fish stocks and even complete depletion in some regions. Fish farming allows establishment of artificial fish colonies that are provided with sufficient feeding, protection from natural predators and competitive threats, access to veterinarian service, and easier harvesting. In many cases, fish cages are used. These are placed in lakes, ponds, rivers, or oceans to contain and protect fish until they can be harvested. They can be constructed of a wide variety of components. Fish are stocked in cages, artificially fed, and harvested when they reach market size. In the salmonid farming industry, for example, Atlantic salmon or rainbow trout are transported live by well-boats from fish farms to centralized processing plants where the fish are slaughtered and processed. A well-boat is a fishing vessel with a well or tank for the storage and transport of live fish. Transportation involves the removal of the fish from their cages to the well-boat, transportation to a processing plant and removal of the fish from the well-boat to the processing plant. After transport, the fish are either pumped directly to the slaughter line or into net pens located at the quay-side (waiting cage) next to the processing plant where the fish are kept before slaughter. Another major issue in fish farming is the health of the fish when in its sea cage. In the case of salmon, sea lice, can cause deadly infestations of both farm-grown and wild salmon. Sea lice are ectoparasites which feed on mucus, blood, and skin, and migrate and latch onto the skin of wild salmon during free-swimming. Large numbers of highly populated, open-net salmon farms can create exceptionally large concentrations of sea lice which can infect wild salmon. Treatment of the parasites may also require removal of the fish from cages. In both processing and treatment, there is a need to safely and humanely transport fish in a manner that minimises harm, damage and stress. Pumps and pipes are often used to move fish from cages and pens to well-boats and from well-boats to processing facilities. Pumps used to move fish from a crowd pen should be well maintained to avoid damage to the fish. The pump determines the speed and rate at which fish are delivered, therefore careful consideration is needed when deciding which pump is most suitable. The following types of pump may be used. An air lift pump works by bubbling air up into the pipe, lifting the fish and the water with it. A venturi pump cause a rapid flow offish through the pipe. These pumps are capable of delivering fish in a continuous flow down long pipes. A vacuum pump supplies supply fish in batches. A dual action pump uses two pumps working in tandem, resulting in a continuous supply offish to the stunning point. Pipes are often used to transport fish, The time fish spend in the pipe should be kept to a minimum. Any delay can have an adverse effect on the fish and increase stress levels. CA3040111 A1 discloses a fish pump for the removal of sea lice and improving water flow distribution using flutes to adjust the water flow distribution from the fish inlet. Summary of the Invention In accordance with a first aspect of the invention there is provided a device for transporting aquatic animals, the device comprising: a primary conduit for transporting aquatic animals in a flow liquid in a first direction from a first end to a second end of the primary conduit, the primary conduit having an internal surface with at least one curved surface; a secondary inlet, positioned between the first end and the second end of the primary conduit, the secondary inlet being coupled with the primary conduit such that, in combination, the flow liquid of the primary conduit and a pump liquid from the secondary inlet function as an ejector pump; and wherein the secondary inlet is configured to introduce a flow of pump liquid to the primary conduit in the first direction and in proximity to the at least one internal curved surface such that at least part of the flow of pump liquid is along the primary conduit at or near the curved surface of the primary conduit. Preferably, the primary conduit comprises a throat which is a section of the conduit having a smaller cross sectional area. Preferably, the primary conduit has a substantially circular cross sectional area. Preferably, a section of the primary conduit comprises a guard which keeps objects in the flow liquid away from the internal surface of the primary conduit. Preferably, the guard is positioned downstream of the ejector pump. Preferably, the guard is positioned upstream of the ejector pump. Preferably, the guard comprises a plurality of guard members. Preferably the guard member comprises a radially extending elongate member operatively connected to the internal wall of the conduit. Preferably, the guard member comprises a wire form guard. Preferably, the device further comprises an additional secondary inlet arranged in series with the secondary inlet on the primary conduit. Preferably, the secondary inlet is concentric with the primary conduit such that the pump liquid is introduced into the primary conduit circumferentially around the whole or part of the circumference of the primary conduit. Optionally, the secondary inlet comprises one or more discrete inlets on the circumference of the primary conduit. Preferably, the secondary inlet has a liquid feed. Preferably, the liquid feed comprises a conduit which provides liquid to the secondary inlet. Preferably, the liquid feed comprises a plurality of conduits arranged around the secondary inlet. Preferably, the liquid feed comprises a pair of conduits arranged around the secondary inlet. Preferably, the secondary inlet comprises a channel. Preferably the channel is orientated at an angle towards the direction of flow of the flow liquid in the primary conduit. Preferably, the angle is an acute angle. Preferably, the angle is between 15° and 35°. More preferably, the angle is between 20° and 25°. Preferably, the secondary inlet further comprises a profiled lip positioned at an intersection between the primary conduit and the secondary inlet. Preferably, the primary conduit further a first section upstream of the secondary inlet and a second section downstream of the secondary inlet. Preferably, at least part of the second section downstream of the secondary inlet has a smaller cross sectional area than that of the first section. Optionally, at least part of the second section downstream of the secondary inlet has a larger cross sectional area than that of the first section. Optionally, part of the second section downstream of the secondary inlet has the same cross sectional area than that of the first section. Brief Description of the Drawings Embodiments of the present invention will now be described, by way of example only, with reference to the drawings, in which: Figure 1a is a side view of a first embodiment of the present invention and figure 1b is a front view of the first embodiment of the present invention; Figure 2a and figure 2b are perspective cross-sectional views of an embodiment of the present invention; Figure 3 is a side schematic which shows various nozzle angles which may be used in embodiments of the present invention; Figure 4 is a cut away perspective illustration of an example of a nozzle tip as used in at least one embodiment of the present invention; Figure 5 is a side schematic view of an example of a pump in accordance with the present invention with a first set of pipe and nozzle dimensions; Figure 6 is a side schematic view of an example of a pump in accordance with the present invention with a second set of pipe and nozzle dimensions; Figure 7 is a side schematic view of an example of a pump in accordance with the present invention with a constant pipe width; Figure 8 is a side schematic view of an example of a pump in accordance with the present invention with a narrow pipe section; Figure 9 is a side schematic view of an example of a pump in accordance with the present invention which uses two pumps arranged in series; Figure 10 is a side schematic view of an example of a pump in accordance with the present invention with internally mounted guide members and 10b is a perspective schematic view of an example of guide members suitable for use in at least one embodiment of the present invention; Figure 11 is a side schematic view of an example of the pump of figure 9 which shows fish guided through the pipe; Figure 12 is a side schematic view of an example of the pump without guide members showing fish in the pipe; and Figure 13 is a side schematic view of an example of a pump in accordance with the present invention which uses two pumps arranged in series and which includes guide members. Detailed Description of the Drawings An object of the present invention is to create an pump for transporting fish which minimises the physical damage and stress experienced by the fish during transportation. The use of an ejector pump and a direction of flow from the nozzle which allows the ejected liquid to at least partially adhere to the side of the conduit improves the stability and consistency of flow whilst also ensuring that the fish are transported along the pipe safely and at a suitable speed. In one example of the present invention, the target volumetric flow rate is around 4,800 gpm(0.36 m3 / s), the pipe diameter 300 mm. A mean velocity through pipe 5.15 m / s and a minimum velocity of 2 m / s is specified to prevent fish swimming against the flow direction. A Max. head of 8 m (776.95 kPa) is used to transport fish of up to 4.5 kg. A wall mounted guard, typically a rail or mesh may be used to protect the fish from the annular nozzle. Figure 1a is a side view of a first embodiment of the present invention and figure 1b is a front view of the first embodiment of the present invention. The figures show a pump 1 which comprises a primary conduit 3 through which water flows in a first direction 5 in order to transport aquatic animals, typically live fish from a first location which may be a well-boat to a second location such as a processing plant. The primary conduit has a first end 7 and a second end 9 which is downstream of the first end 7. A secondary inlet is shown which comprises inlet pipes 11, 13 which are positioned at opposing sides of the pump 1. The inlets 11,13 contain a pump liquid, typically water, which is fed into a plenum or fluid cavity and into the primary conduit via a nozzle as shown in the example of figures 2a and 2b. Figure 2a and figure 2b are cross sectional perspective views of a pump 21 in accordance with the present invention. Pump 21 comprises a primary conduit 22 and a fluid cavity or plenum 23 which is the secondary inlet and has an angled front portion 25 which has a nozzle 27 positioned at the junction between the angled front portion 25 of the fluid cavity 23 and the primary conduit 22. The secondary inlet is concentric with the primary conduit such that the pump liquid is introduced into the primary conduit circumferentially around the whole or part of the circumference of the primary conduit. In use, fish or other aquatic animals are fed through the primary conduit 22 in a flow liquid which is flowing in a first direction 29 from the first end 31 to the second end 33 of the primary conduit 22. As is apparent, in this embodiment, the primary conduit 22 is a pipe which has a curved, substantially circular cross section. The secondary inlet 23 is positioned between the first end 31 and the second end 33 of the primary conduit 22. The secondary inlet is a plenum or fluid cavity which has an angled front portion 25 and a nozzle 27. The secondary inlet 23 supplies a pump liquid into the direction of flow 29 of the primary conduit 29 such that the flow liquid of the primary conduit and the pump liquid from the secondary inlet function as an ejector pump. In addition, the secondary inlet 23 is configured to introduce a flow of pump liquid to the primary conduit 22 in the first direction and in proximity to the internal curved surface such that at least part of the flow of pump liquid is along the primary conduit at or near the curved surface of the primary conduit. In this embodiment of the present invention, the angled front portion determines the direction of flow of the pump liquid into the primary conduit. The position and shape of the nozzle also assists in determining various priorities of the fluid flow, such as cavitation. Figure 3 shows a pump 41 with a primary conduit 43 through which a transport liquid passes in flow direction 45 from a first end 47 to a second end 49. The angle of the front portion 51 is factor which determines the direction of flow of the pump liquid into the primary conduit. The diagram of figure 3 shows four examples of the angle of the front portion between 0° and 45°. One feature of angling the fluid is that it the fluid will partially adhere to the curved surface of the primary conduit. This property of the fluid is explained by the Coanda effect. Adherence of the fluid to the wall of the primary conduit will help avoid the creation of turbulent flow in the pipe, which can harm the fish as they are transported through the pipe. In addition this will keep the pump fluid jet away from the pathway of the fish through the conduit. Figure 4 is a cut away perspective illustration of an example of a nozzle tip 65 in the front portion of an angled front portion 63 of channel 61. In this example, the tip 65 is profiled. The profile of the tip 65 may also be a determining factor in the direction of fluid flow and in the extent to which cavitation occurs in the fluid flowing downstream of the fluid inlet. The inlet may have a profiled lip which assists with cavitation. Changes in angles and dimensions of components of the pump may be made to optimise performance for different conditions. As is apparent in the following examples of the present invention, the conduit diameter, associated area and the area of the inlet gaps may be set to control the flow and entrainment characteristics of the ejector. Figures 5 and 6 show embodiments of the present invention in which the diameter of the primary conduit is altered along its length. Figure 5 is a side schematic view of an example of a pump 71 in accordance with the present invention with a first set of pipe and nozzle dimensions. The pump has a primary conduit with a first pipe diameter 73 upstream of the secondary inlet and a second pipe diameter 77 downstream of the secondary inlet. The inlet gap 75 is the space through which pump fluid enters into the primary conduit. The entrainment ratio increases as the ratio of the area of inlet gap 75 to pipe area (at diameter 73) decreases. Figure 6 is a side schematic view of an example of a pump 81 in accordance with the present invention with a first set of pipe and nozzle dimensions. The pump has a primary conduit with a first pipe diameter 83 upstream of the secondary inlet. The pipe is widened to a second diameter 85 downstream of the first pipe diameter 83 but upstream of the secondary inlet. Pipe diameter 89 narrows downstream of the secondary inlet. The inlet gap 87 is the space through which pump fluid enters into the primary conduit. Locally increasing the diameter 85 has a mildly negative impact on entrainment. Figures 7 and 8 compare properties of embodiments of the present invention with a straight primary conduit of constant diameter and one in with a narrower pipe diameter section. Figure 7 is a side schematic view of an example of a pump 81 in accordance with the present invention with a constant pipe width 93. Figure 8 is a side schematic view of an example of a pump 101 in accordance with the present invention. The pipe diameter 105 of the primary conduit upstream of the secondary inlet is shown. Immediately downstream of the secondary inlet, the pipe diameter is narrowed to comprise a throat section. The purpose of the throat is to increase the velocity of the flow and at the same time reduce the pressure. In this example, the throat section had a diameter of 0.225m compared with the 0.3m standard diameter and the throat has a negative impact on the entrainment. The entrainment ratio increases with decreasing area ratio, however, cavitation becomes a limit factor at lower area ratios. At lower entrainment ratios and primary mass flow rates, the secondary flow rate falls below acceptable levels with regards to the mean velocity requirement of 2 m / s. An area ratio of between 0.2 to 0.4 is preferred. Figure 9 is a side schematic view of an example of a pump system 111 in accordance with the present invention which uses two pumps arranged in series. The pump system 111 comprises a first inlet 113 upstream of the pumps 114, 116 and an outlet 115, downstream of the pumps 114, 116. Pump 114 has a primary conduit with diameter 117 (A1) and first inlet gap 119 (A2a). Pump 116 has a primary conduit with the same diameter as that of pump 114 but an first inlet gap 121 (A2b) with different dimensions to inlet gap 119. Area ratio ((A2a+A2b) / A1) may be varied between 0.05 and 0.2 in examples of the invention which correspond to the general arrangement shown in figure 9. Figure 10 is a side schematic view of an example of a pump 131 in accordance with the present invention with internally mounted guide members. Figure 10 a shows a pump 131 which comprises a primary conduit 133 through which water flows in a first direction 5 in order to transport aquatic animals, typically live fish from a first location which may be a well-boat to a second location such as a processing plant. The primary conduit has a first end 137 and a second end 139 which is downstream of the first end 137. A secondary inlet is shown which comprises inlet pipes 141, 143 which are positioned at opposing sides of the pump 131. The inlets 141, 143 contain a pump liquid, typically water, which is fed into a plenum or fluid cavity and into the primary conduit via a nozzle. Figure 10a further comprises a wall guard 145 which in this embodiment comprises a set of parallel wires 147 which are attached longitudinally in the primary conduit. The guard extends from a position upstream of the secondary inlet 144 to a position downstream of the secondary inlet 144. Figure 10b is a perspective schematic view of an example of guide members 147 coupled 149 to the inner wall of primary conduit. In use, fish or other aquatic animals are fed through the primary conduit 133 in a flow liquid which is flowing in a first direction 135 from the first end 137 to the second end 139 of the primary conduit 133. The secondary inlet 144 supplies a pump liquid into the direction of flow 135 of the primary conduit 133 such that the flow liquid of the primary conduit and the pump liquid from the secondary inlet function as an ejector pump. Figure 11 is a side schematic view of an example of the pump of figure 10 which shows fish guided through the pipe. The fish are shown in three positions, upstream of the secondary inlet 151. At the secondary inlet nozzle 153 and downstream of the secondary inlet 155. I positions 153 and 155, the guide member keeps the fish located towards the centre of the primary conduit. Figure 12 is a side schematic view of an example of the pump 161 without guide members showing fish in the pipe. The fish are shown in three positions, upstream of the secondary inlet 163. At the secondary inlet nozzle 165 and downstream of the secondary inlet 167. In positions 153 and 155, the fish move off centre, possibly as a consequence of the additional pump pressure at the nozzle. Figure 13 is a side schematic view of an example of a pump assembly 171 in accordance with the present invention which uses two pumps 173 and 175 arranged in series. Both pumps have guide members. In the specification the terms "comprise, comprises, comprised and comprising" or any variation thereof and the terms include, includes, included and including" or any variation thereof are considered to be totally interchangeable and they should all be afforded the widest possible interpretation and vice versa. The invention is not limited to the embodiments hereinbefore described but may be varied in both construction and detail.

Claims

1. A device for transporting aquatic animals, the device comprising:a primary conduit for transporting aquatic animals in a flow liquid in a first direction from a first end to a second end of the primary conduit, the primary conduit having an internal surface with at least one curved surface;a secondary inlet, positioned between the first end and the second end of the primary conduit, the secondary inlet being coupled with the primary conduit such that, in combination, the flow liquid of the primary conduit and a pump liquid from the secondary inlet function as an ejector pump; and whereinthe secondary inlet is configured to introduce a flow of pump liquid to the primary conduit in the first direction and in proximity to the at least one internal curved surface such that at least part of the flow of pump liquid is along the primary conduit at or near the curved surface of the primary conduit.

2. The device as claimed in claim 1 wherein, the primary conduit comprises a throat which is a section of the conduit having a smaller cross sectional area.

3. The device as claimed in claim 1 or claim 2 wherein, the primary conduit has a substantially circular cross sectional area.

4. The device as claimed in any preceding claim wherein, a section of the primary conduit comprises a guard which keeps objects in the flow liquid away from the internal surface of the primary conduit.

5. The device as claimed in claim 4 wherein, the guard is positioned downstream of the ejector pump.

6. The device as claimed in claim 4 or claim 5 wherein, the guard is positioned upstream of the ejector pump.

7. The device as claimed in any of claims 4 to 6 wherein, the guard comprises a plurality of guard members.

8. The device as claimed in claim 7 wherein, the guard member comprises a radially extending elongate member operatively connected to the internal wall of the conduit.

9. The device as claimed in claim 7 or claim 8 wherein, the guard member comprises a wire form guard.

10. The device as claimed in any preceding claim wherein, the device further comprises an additional secondary inlet arranged in series with the secondary inlet on the primary conduit.

11. The device as claimed in claim 10 wherein, the secondary inlet is concentric with the primary conduit such that the pump liquid is introduced into the primary conduit circumferentially around the whole or part of the circumference of the primary conduit.

12. The device as claimed in claim 10 or claim 11 wherein, the secondary inlet comprises one or more discrete inlets on the circumference of the primary conduit.

13. The device as claimed in any of claims 10 to 12 wherein, the secondary inlet has a liquid feed.

14. The device as claimed in claim 13 wherein, the liquid feed comprises a conduit which provides liquid to the secondary inlet.

15. The device as claimed in claim 13 wherein, the liquid feed comprises a plurality of conduits arranged around the secondary inlet.

16. The device as claimed in claim 13 wherein, the liquid feed comprises a pair of conduits arranged around the secondary inlet.

17. The device as claimed in claim 10 wherein, the secondary inlet comprises a channel.

18. Preferably the channel is orientated at an angle towards the direction of flow of the flow liquid in the primary conduit.

19. The device as claimed in claim 18 wherein, the angle is an acute angle.

20. The device as claimed in claim 19 wherein, the angle is between 15° and 35°.

21. The device as claimed in claim 19 wherein, the angle is between 20° and 25°.

22. The device as claimed in claim 10 wherein, the secondary inlet furthercomprises a profiled lip positioned at an intersection between the primary conduit and the secondary inlet.

23. The device as claimed in any preceding claim wherein, the primary conduit further comprises a first section upstream of the secondary inlet and a second section downstream of the secondary inlet.

24. The device as claimed in claim 23 wherein, at least part of the second section downstream of the secondary inlet has a smaller cross sectional area than that of the first section.

25. The device as claimed in claim 24 wherein, at least part of the second section downstream of the secondary inlet has a larger cross sectional area than that of the first section.

26. The device as claimed in claim 24 wherein , part of the second section downstream of the secondary inlet has the same cross sectional area than that of the first section.

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