Fish pump

An improved liquid pump for transporting live fish or other products in an induced flow has secondary line with one end to be placed in a pool of liquid containing fish or other products. The other end of the line is connected to a housing having an internal pump chamber. A primary intake has one end connected to a reservoir of liquid and the other end connected to the housing concentrically about the secondary line. As liquid flows through the primary intake into the pump chamber and out the outlet, the Coanda effect results in a low pressure area in the pump chamber. The liquid in the secondary line is induced to fill the low pressure area. By shaping and directing the primary intake and the secondary intake within the pump chamber a more efficient pump is produced.

FIELD OF THE INVENTION

This invention relates to the fishing industry and, more particularly, to fish pumps capable of moving a liquid containing fish or other fragile organisms.

BACKGROUND OF THE INVENTION

In the fishing industry, including the aquaculture industry, and the food industry, as a whole, a primary objective is to move large numbers of products without damage from the source to the marketplace. Fish present a particular problem due to their strength yet fragile structure. The movement of fish, whether from fish nets or retention areas, is most desirable if the fish is not injured during the transfer.

For instance, in commercial fishing the use of a fishing net to pull fish into a boat can result in injury or death to the fish. If the fish are transferred directly from the fishing net into a holding tank on the fishing boat by use of a fish pump, the fish can be transferred without injury thereby delaying the processing time. Current fish pumps have limited size capacity and transporting larger fish can result in severe damage to the fish. Unfortunately even when the current fish pumps are used within a capacity range, the pump designs can lead to excessive stress upon the fish due to wall impact where pressurized water meets the fish laden water.

If the fish is injured, a loss of blood can occur which not only affects the well being of the fish but if the fish is about to be harvested, the blood loss has a direct correlation on the amount of income obtained in a sale of the fish since fisherman are paid by the pound and the loss of blood is a loss of weight.

Transferring the catch from fishing trawlers to the processing docks and harvesting the contents of a growing tank at an aqua-farm require efficient handling of large volumes of water containing live fish or marine organisms. While fishing and aqua-culture are specific examples, there are other industries that move products using liquids as carriers.

In using a Coanda effect pump to transport live fish, the mobility of fish is lessened in reference to the direction of travel because of the flow into the pump. Since the natural tendency of a fish is move against a current so the fish typically enter such a pump swimming into the suction flow thereby entering a secondary intake line tail first. The suction flow in the secondary intake line results from the hydraulic forces of the mixing liquids in the pump chamber creating an induced flow. As the primary flow and induced flow intermix through the pump, the energy becomes uniform in the outlet flow. The problem with such conventional pumps is the sudden turbulence or swirl due to the differential energy in the circumferential primary flow and the inner column of induced flow. Large active fish can be severely injured at this junction wherein scales and fins can be torn off or side wall impact so severe that the fish can killed.

When the fish enters tail first, it can do little to prevent impacting of the walls of the pump as it passes through. Also, when the fish encounters the water swirl formed at the point of water mixing, the forward motion through the pump with deceleration then acceleration results in the likely impact against the wall of the pump.

Such a pump has inherent efficiency due the shear collision effect between the primary liquid injected through the Coanda inlet and the secondary liquid carrying the fish but also from the suction effect created by the action of the primary liquid on the Coanda surface. In such a pump, a first segment upstream of the Coanda surface diverges from its inlet end and terminates at its outlet end immediately before the point of injection of the primary liquid from the Coanda orifice. The inside diameter of the outlet end of the first segment is larger than the inside diameter of the second segment downstream of and smoothly merging with the Coanda surface. A second segment converges downstream from the Coanda orifice and, thereafter, diverges from the minimum inside diameter location.

In the prior art, the first segment diverged abruptly from its inlet end to the outlet end located adjacent the primary liquid injection point through the orifice. The Coanda surface converged to a first inside diameter which was located downstream from the first segment. The inside diameter downstream from the first segment was smaller than the inside diameter of the outlet end of the first segment. For that reason, a fish traveling from the first segment would impact with the converging Coanda surface, thereby causing fish damage or fish kill. Further in the area of the Coanda orifice, there is a low pressure or “suction” zone created by the primary liquid injection which impairs momentum to the secondary liquid flow. However, since the first segment diverged, at the point of primary fluid injection there was a reduced velocity in the first segment due to the increased cross section. This reduced velocity and increased area allowed the secondary fluid to be pulled through the second segment by the Coanda effect around the perimeter of the second segment only and an undesirable no flow or reverse flow condition was allowed to exist in the center or core of the second segment. Under some conditions, the core effect would extend into the inlet end of the first section. When such core effect took place, the no flow or reverse flow core would be able to reverse and re-enter the second segment around the perimeter of the second segment due to the Coanda effect. This would satisfy the low pressure area created by the primary fluid injection over the Coanda surface allowing a loss of secondary fluid flow and unacceptable turbulence in the area of primary injection.

Still another known problem of the prior art Coanda effect pumps was created by the divergence of the second segment from the minimum throat diameter at the Coanda surface to the downstream end of the second segment. This divergence created a larger cross section in the second segment downstream of the Coanda surface and would not permit the effective transfer of the primary fluid momentum throughout the entire cross section of the second segment. This allowed a core of unaffected secondary fluid to exist in the center of the second segment and, under extreme conditions, to extend upstream into the first segment. Such a core resulted in unnecessary turbulence and loss of efficiency.

Yet a further problem with the previous pump related to the liquid injection through the Coanda orifice from the plenum which contained the primary liquid used for injection through the orifice. As the distance from the bottom of the pump increased, the primary liquid would not flow directly radially inwardly after leaving the peripheral injection orifice but, rather, would curve downwardly when viewed from the end. This decreased the Coanda effect and, hence, the efficiency of the pump.

The patent to Breckner et al, U.S. Pat. No. 5,018,946 addressed a number of the prior art pump problems by disclosing an improvement of earlier designs to address the reverse flow in the low pressure area created by the Coanda effect. Another problem addressed by the patent was excessive turbulence in the boundary layer between the primary flow and the secondary column. As a solution to these stated problems, the Breckner et al device adds fins or vanes in the flow path of the primary flow to increase uniformity in the primary flow by the Coanda surface. The angle of the convergence of the primary flow and the secondary flow is increased to reduce the area of transition between the primary flow and the secondary flow. However, the reduction of the transition area increases the turbulence and acceleration. The secondary flow path is designed for transferring fish of about 1-10 pounds and 8 inches in diameter. Although larger sizes are disclosed as possible, the loss of water uniformity occurs at the Coanda surface and fish over 8 inches in diameter as again subjected to injury or death.

Using conventional designs, in order to increase either the size of the product transported or height to be lifted (head) or both, more energy must be added to the primary flow. To increase the size of the reciprocating or centrifugal pump is very expensive and the effects of the greater pressures and velocities of the liquid, in the Coanda effect pump, may cause more trauma to the product. The '946 pump is limited in efficiency to pump diameters of 8 inches or less.

Nagata, U.S. Pat. No. 4,487,553, discloses a jet pump for transporting a liquid utilizing a primary flow and a secondary flow. The primary flow originates from an annular orifice with notches in the periphery.

A further problem, solved by the instant invention, is an ability to feed fish raised in a floating cage. A common method of raising fish on a fish farm is the use of a floating cage placed in a river, lake, ocean or the like open water. A major concern with floating cages is change in the water conditions, in particulary, changes that occur due to high winds or a storm. Should a breach of the cage occur, the entire stock of fish may escape. Currently, the fish raised on a farm can be fed by hand or automatic feeders. One can appreciate that the difficulty in feeding is raised when fish food is placed on the surface of the water with the reliance of gravity to feed the fish. When high winds or a storm occurs, wave action can result in a breach of the structure leading to a loss of fish.

One known prior art method of addressing rough waters is to use underwater fish cages so as to avoid surface waves. However, feeding of the fish becomes difficult since feeding must now address the body of water above the cage which may include a current. A known device to overcome food drift is the use of gravity tubes which are very slow and require a boat or barge to be positioned directly over the cage.

Another way of feeding fish held in an underwater cage is by use of a pump. However, typical food for farm fish is in a pellet form which is damaged by most pumps. Damaging of the fish pellets results in smaller size matter which may not be detected by the fish before floating away.

What is needed in the art is an efficient liquid pump that can safely transport larger fish over a greater head yet minimize turbulence and swirl to reduce fish stress and damage. What is further needed in the art is an efficient liquid transfer pump capable of transferring fish food beneath the surface of a body of water.

SUMMARY OF THE PRESENT INVENTION

The present invention is directed toward an improved Coanda effect pump for transporting liquid and associated product by induced flow. The pump has a housing with a primary intake for primary flow, a secondary intake for induced flow, an internal pump chamber for intermixing said primary flow and said secondary flow, and an outlet for discharge. The primary intake and said secondary intake are constructed and arranged so as to terminate in a orifice within the housing. The orifice allows the primary flow to be circumferential with the induced flow with both primary flow and induced flow exiting said orifice into a pump chamber. The orifice includes a circumferential gap between the primary intake and the housing directing the primary flow into the pump chamber at an acute angle to the axis of the induced flow. The secondary intake has an internal surface and an external surface with the orifice having flutes formed in the external surface of the secondary intake. An enlarged mouth extends a distance within the internal surface of said secondary intake. The mouth has a constant diameter for forming the secondary flow whereby the primary flow and the secondary flow intermix in the pump chamber with minimal swirl to inhibit damage to the product passing through the pump.

Therefore, it is an objective of this invention to provide a Coanda effect pump which creates a high speed boundary layer with a means for then breaking up the boundary layer to increase the efficiency of intermixing of the primary flow and the induced flow.

Still another objective of the invention is to teach the use of orifice serration and a discharge nozzle, wherein Coanda pumps with small gaps can be configured to have higher efficiencies than large gaps, allowing very high induced flows from a primary pump at low flows.

It is another objective of this invention to provide a transition zone in the pump chamber and a discharge velocity that does not injure live fish providing a pump system that is more efficient with smaller gaps.

It is yet another objective of this invention to teach the reduction of the angle of convergence between the primary flow and the induced flow thereby reducing the turbulence and swirl in the flow.

A further objective of this invention is to teach disrupting the boundary layer between the primary flow and induced flow to more quickly intermix with the induced flow.

A further objective of this invention is to teach a fish friendly Coanda effect pump having an 8 inch or larger diameter. The pump made efficient by reducing or eliminating the back flow and swirl created in high lifts.

Another objective of the invention is to provide a highly efficient pump that can move large diameter fish including salmon as well as high volume of smaller items such as herring and mussels.

Another use for the invention is to provide a highly efficient pump capable of transferring fish food with minimal or no breakage of the food to an underwater cage.

DETAILED DESCRIPTION OF THE INVENTION

The Coanda effect pump10, illustrated inFIG. 1, is constructed with two intakes, a primary intake for the primary liquid flow and a secondary intake for the induced liquid flow, a pump chamber, and one outlet for the discharge or work product. The primary liquid flow60is created by a source of power, such as a centrifugal pump (not shown) moving a large volume of liquid, connected to the primary intake. The source liquid for the primary flow60may be held in a reservoir (not shown) fed by a separate source of clean liquid, part of a closed system in which the discharge is filtered or otherwise cleaned and returned to the reservoir, or from a source of unlimited make-up water such as an ocean, lake, or river. The source liquid is of suitable consistency to pass through the power pump without interruption and develop a steady flow. The preferred liquid is water.

The induced liquid flow70is a reaction flow created by the low pressure area existing in the pump chamber and is drawn into the pump through the secondary intake11. The secondary intake for the induced flow is connected to a line (not shown) that can be introduced into a body of liquid containing the fish or product to be transported. This line may be flexible for maneuverability. The primary liquid, the secondary liquid and the articles are discharged through the outlet12of the pump chamber. The outlet12is connected to the nozzle80which is formed in a bell shape with the mouth approximately twice the diameter of the outlet12. The nozzle80may be connected to a line for directing the discharge to perforated collecting bins (not shown) which separate the product from the carrier liquid. The nozzle80may be removably connected to outlet12or formed integrally therewith. The velocity of the discharge flow must be slow enough to prevent trauma to the product during the collection. This velocity is directly related to the power of the primary flow and the degree of intermixing with the induced flow.

Now with reference toFIGS. 2 and 3, the primary intake13is part of the outer casing30of the pump. The primary liquid flow60from the power pump enters the intake13and fills the plenum31. Secondary intake11is connected to the outer casing30and extends through the plenum31. The outlet12is illustrated as being attached to the outer casing30by bolts40extending through a flange41screwed into the outer casing30, though alternative fastener means may be used. The outer casing30terminates in a flange37which includes a seal ring38in a seal groove39. As illustrated, the primary intake, secondary intake, and plenum of the Coanda effect pump are a one piece design however, the elements may be separately made and joined together by welds, bolts, adhesives or autologous bonding. The outer casing and the outlet form the housing of the pump.

The plenum31is the space between the inner wall25of the outer casing and the outer wall33of the intake11. The closed bottom32of the plenum is formed by the outer casing30and the secondary intake. The plenum acts as a pressure and flow regulator for the primary flow60to insure a uniform flow of primary fluid through the orifice17into the pump chamber50. The orifice17forms the opening connecting the plenum and the pump chamber50. The side walls of the orifice determine the angle of the primary flow60into the pump chamber50. The side walls of the orifice are shaped by the inner wall35of the outlet12and the outer end19of the secondary intake11. However, the primary flow60is also affected by the shoulder15on the secondary intake11within the plenum31.

The inner wall34of the secondary intake11has an area of increased diameter adjacent the opening18. The enlarged mouth21of the intake11reduces pressure immediately before the induced flow is ejected into the pump chamber. This change may also reduce the integrity of the boundary layer of the induced flow. The serrations or flutes20on the outer end19of the secondary intake11disrupt the cross section of the primary flow into the pump chamber50. The crennelated cross section is thought to reduce the symmetry of the boundary layer and provide more surface area for mixing of the primary flow with the induced flow. In a preferred embodiment, the flutes are approximately 0.25 in. deep and 0.25 in. in radius and uniformly spaced about the circumference of the intake. The flutes may range from as little as 18 degrees apart to the preferred embodiment of about 36 degrees apart.

A diverging and then parallel or converging diameter prior to the primary water junction operates to introduce the secondary or suction water as close to parallel flow to primary water as possible. The ratio of the inlet diameter to the diameter of the primary water orifice junction is 1 to 1.2 or less.FIG. 4further depict the serrations or flutes20on the outer end19of the secondary intake which disrupt the cross section of the primary flow into the pump chamber. The flutes are formed20along the outer surface17of the mouth of the secondary intake wherein the flutes are formed as depressions along the outer surface17which do not extend to an inner surface of the intake. The crennelated cross section reduces the symmetry of the boundary layer and provides more surface area for mixing of the primary flow with the induced flow. As previously stated, in a preferred embodiment, the depressions which form the flutes are approximately 0.25 in. deep and 0.25 in. in radius and uniformly spaced about 36 degrees about the circumference of the intake.

The diverging exit nozzle80shown inFIG. 1provides a discharge feature wherein the internal volume is increased thereby reducing pressure.

The following table illustrates the properties of the pump of this invention, based on an 8 inch I.D. Coanda effect pump:

GapGapPressureFlow ratioangle deg.in.PSIA*B*C*D*430.412.3620.4430.322.508.532.528.543430.218.560.60.570.596350.418.440.470350.324.528.552350.226.592.622.623.640250.420.457.471250.324.582.60250.226.651.674.707.739The flow ratio is the amount of induced flow per primary flow expressed as a percentage.A = Coanda effect pump of the prior art;B = Coanda effect pump of the prior art using a discharge orifice of the instant invention.C = Coanda effect pump of the instant invention having a serration feature;D = Coanda effect pump of the instant invention having a the discharge orifice, serration feature, and using a discharge nozzle.

A pump of the prior art having a gap injection angle of 43 degrees and 0.4 inches has a flow ratio of 0.362. The addition of a discharge nozzle increase the flow ratio to 0.4.

If the gap injection angle of 43 degrees is maintained but the gap reduced to 0.3 inches, the efficiency allows a flow ratio of 0.508. The addition of the discharge orifice of this invention increases the flow ratio to 0.532. If the flutes are present on the orifice, but no discharge nozzle, the efficiency is raised from 0.508 to 0.528. If the discharge nozzle is included with the orifice flutes, then the efficiency is raised from 0.508 to 0.543.

If the gap injection angle of 43 degrees is maintained but the gap angle reduced to 0.2 inches, the efficiency allows a flow ratio of 0.560. The addition of a discharge orifice increases the flow ratio to 0.600. If the flutes are present on the orifice, but no discharge nozzle, the flow ratio is raised from 0.560 to 0.570. If the discharge nozzle is included with the orifice flutes, then the flow ratio is raised from 0.560 to 0.596.

A pump of the prior art having a gap injection angle of 35 degrees and 0.4 inches has a flow ratio of 0.440. The addition of a discharge orifice increases the flow ratio to 0.470.

If the gap injection angle of 35 degrees is maintained but the gap angle reduced to 0.2 inches, the efficiency allows a flow ratio of 0.592. The addition of a discharge orifice increases the flow ratio to 0.622. If the flutes are present on the orifice, but no discharge nozzle, the flow ratio is raised from 0.592 to 0.623. If the discharge nozzle is included with the orifice flutes, then the flow ratio is raised from 0.592 to 0.640.

A pump of the prior art having a gap injection angle of 25 degrees and 0.4 inches has a flow ratio of 0.457. The addition of a discharge orifice increases the flow ratio to 0.471.

If the gap injection angle of 25 degrees is maintained but the gap angle reduced to 0.2 inches, the efficiency allows a flow ratio of 0.651. The addition of a discharge nozzle increases the flow ratio to 0.674. If the flutes are present on the orifice, but no discharge nozzle, the flow ratio is raised from 0.651 to 0.707. If the discharge nozzle is included with the orifice flutes, then the flow ratio is raised from 0.651 to 0.739.

The test performed evidences that the prior art pump having a 43 degree angle and 0.4 inch gap can have the flow ratio increased from 0.362 to 0.739 by use of a 25 degree angle with a 0.2 inch gap wherein the orifice is fluted and a discharge nozzle is added to the pump. Coanda pumps with small gaps can be configured to have higher efficiencies than with large gaps. Thus, the pump system can be most efficient with smaller gaps and angle which further allows increased product protection of the items transferred.

The inner and outer walls of the shaped gap, the flutes and the mouth combine to form the orifice18. The angle and cross section of the primary flow relative to the axis and surface tension of the induced flow determine the characteristics of the combined flow in the transition zone of the pump chamber. These features shape the low pressure area, provide for gradual acceleration and reduce the intermixing swirl thereby increasing efficiency of the pump. The exit diameter of the diverging exit orifice is no more than twice the pump bore diameter. The injection angle can be expressed in degrees that is less than 3.5 times the pump diameter expressed in inches.

The internal diameter of the secondary intake11is such that articles, such as live fish weighting up to 20 pounds, may be raised to a head over 15 feet without damage. Similarly, the efficiency of the instant pump allows high volume transfer of smaller items such as mussel without damage. High volume transfer is critical to those in a transfer position where time is of the essence. For instance, the transfer of fish from a fishing boat to a hauling boat are commonly performed while at sea which allows the fishing boat to empty its storage area to permit an extended fishing expedition. The time spent in transferring of the fish results in a lost profit since the fishing boat crew is idled during the transfer. Further to this example, the fishing opportunities must be realized when the fish are available, thus, assuring the quick return of the fishing boat to its designated function is a requirement to realize profits.

The pump of the instant invention can be further used to move fish feed pellets to an underwater fish cage without causing breakage of the feed pellets. Referring now to FIG.5, the coanda effect pump system for transferring of the fish pellets is illustrated. A vessel100is shown floating on a body of water102. The vessel is used to carry fish food over a fish cage wherein a centrifugal pump104or the like is used for pulling of a primary water supply from the body of water through intake106. The primary water supply is transferred to the coanda effect pump108. A secondary inlet to the pump108includes a finely perforated pipe110that will allow water to fill the pump but not allow for loss of feed pellets. A funnel shaped receiver110can be used for insertion of feed pellets into the pipe110wherein suction will draw the pellets into the secondary suction of the pump108. It should be noted that the fish food can be inserted into the pipe110by the use of a shovel, or automatically transferred into the pipe110by use of an auger or other metering device. The output of the feeder is coupled to a flexible feed tube114and the distal end116of the tube114available for positioning near the fish in need of food. The tube114may include a header and valve arrangement, not shown, to direct delivery of the food to multiple or alternate cages. In this embodiment, the coanda effect pump108is placed beneath the water which, together with the feeder pipe110, removes entrapped air from the fish pellets.