INTRODUCTION AND BACKGROUND

This invention relates to liquid intakes for use with liquid suction devices and more particularly to intakes for use in shallow bodies of liquid.

It is known that the withdrawal by means of a pump system of a liquid, such as water, from a shallow body of the liquid, such as that contained in a shallow dam, pond, pit etc, is problematic. The problems include possible excessive air ingestion and air entrapment during pump operation and the possible drawing in of floating debris including suspended solids such as sand, leaves or any other foreign material that could be found in the body. Air is typically ingested through air entrained submerged and surface vortices. These and other problems negatively affect the operation of the pump system which could result in a reduction in pump performance, excessive vibrations, increased noise and higher power consumption.

A floating liquid intake for a liquid suction removal system is disclosed in WO201 9/119064 in the name of RBH Engineering Pty Ltd. This intake comprises a hollow and buoyant annular member which defines a substantially annular inlet for the ingress of liquid into a cavity of the intake. The intake further comprises a pipe extending into the cavity. The pipe is of substantially uniform cross section and defines an inlet that, in use, is open below a surface of the liquid within the cavity. The pipe extends outside of the cavity for connection to a liquid suction removal system. This liquid intake may not be suitable for at least some applications.

OBJECT OF THE INVENTION

Accordingly, it is an object of the present invention to provide a liquid intake with which the applicant believes the above problems may at least be alleviated or which may provide a useful alternative for the known liquid intakes.

SUMMARY OF THE INVENTION

According to the invention there is provided a liquid intake which is connectable to a liquid suction device, the liquid intake comprising:

- a buoyant liquid receptacle comprising: o a lid; o a base; and o a sidewall extending between the lid and the base;

- the lid, the sidewall and the base collectively defining a chamber of the receptacle;

- the sidewall defining an annular inlet for liquid into the chamber and an outlet for the liquid from the chamber, the outlet being in liquid flow communication with a flaring liquid inlet pipe section defining a mouth at a free end thereof and which inlet pipe section is located in the chamber with the free end in spaced relation relative to the base and the mouth facing the base.

The flaring liquid inlet pipe section may be one of bell-shaped and frusta- conically shaped.

The lid and base may be circular in configuration and the sidewall may be frusta-conical.

The annular inlet may comprise a perforated region of the frusta-conical sidewall. The region may be adjacent the lid.

The lid, the sidewall, the annular inlet, the base and the mouth may be arranged in coaxial relationship with one another on a main axis of the receptacle.

The intake may comprise a baffle arrangement extending from the base in a direction towards the lid. The baffle arrangement may comprise at least first and second elongate baffle plates which intersect in an intersection region and the intersection region may be arranged in line with the main axis.

The first and second baffle plates may extend at 90° relative to one another.

At least one of the at least first and second baffle plates may be perforated to define a plurality of the holes therein.

The baffle arrangement may extend to beyond the free end of the liquid inlet pipe section.

An upper region of the arrangement towards the intersection region may be located inside the liquid inlet pipe section.

According to another aspect of the invention there is provided a liquid intake which is connectable to a liquid suction device, the liquid intake comprising:

- a buoyant liquid receptacle comprising: o a lid; o a flat base; and o a sidewall extending between the lid and the flat base; - the lid, the sidewall and the flat base collectively defining a chamber of the receptacle;

- the sidewall defining an annular inlet for liquid into the chamber and an outlet for the liquid from the chamber, the outlet being in liquid flow communication with a liquid inlet pipe section defining a mouth at a free end thereof and which inlet pipe section is located in the chamber with the free end in spaced relation relative to the flat base; and

- a baffle arrangement extending from the flat base in a direction towards the lid.

The lid and flat base may be circular in configuration and the sidewall may be frusta-conical.

The annular inlet may comprise a perforated region of the frusta-conical sidewall. The region may be adjacent the lid.

The lid, the sidewall, the base, the annular inlet and the mouth may be arranged in coaxial relationship with one another on a main axis of the receptacle. The liquid inlet pipe section may have one of: a constant cross section and an increasing cross section in a direction towards the mouth at the free end.

The baffle arrangement may comprise at least first and second elongate baffle plates which intersect in an intersection region and the intersection region may be arranged in line with the main axis.

The first and second baffle plates may extend at 90° relative to one another.

At least one of the at least first and second baffle plates may be perforated to define a plurality of holes therein.

The baffle arrangement may extend to beyond the free end of the liquid inlet pipe section.

An upper region of the arrangement towards the intersection region may be located inside the liquid inlet pipe section.

BRIEF DESCRIPTION OF THE ACCOMPANYING DIAGRAMS

The invention will now further be described, by way of example only, with reference to the accompanying diagrams wherein: figure 1 a diagrammatic perspective view from above of an example embodiment of a liquid intake; figure 2 a partially exploded perspective view of the liquid intake; figure 3 is a section on line III in figure 1 of the liquid intake located in a body of a liquid; and figure 4 is a bottom view of the liquid intake.

DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

An example embodiment of a liquid intake is generally designated by the reference numeral 10 in figures 1 to 4. In use, the liquid intake 10 is connectable via a suction hose (not shown) to a liquid suction device (also not shown), such as a suction pump, for example a self-priming centrifugal suction pump.

The liquid intake 10 comprises a buoyant liquid receptacle 12 comprising a lid 14, a base 16 (shown in figures 2 to 4) and a sidewall 18 extending between the lid and the base. The lid 14, the sidewall 18 and the base 16 collectively define a chamber 20 of the receptacle 12. The sidewall 18 defines an annular inlet 22 for liquid into the chamber 20. The sidewall also defines an outlet 24 for the liquid from the chamber 20. The outlet 24 is in liquid flow communication with a flaring liquid inlet pipe section 26 defining a mouth 28 at a lip at a free end 30 thereof. The inlet pipe section 26 is located in the chamber 20 with the free end 30 in spaced relation relative to the base 16 and the mouth facing the base.

The receptacle 12 may be manufactured from High-density polyethylene (HDPE) which is naturally buoyant in water. The various parts or elements (which are described in more detail below) of the receptacle may be welded to one another in known manner.

The lid 14 is flat, solid and circular in configuration. Positioning brackets 36 may be provided in equi-spaced positions towards a periphery of the lid. In the example embodiment shown, these positioning brackets 36 are located peripherally at 90 ^s increments on lid 14. A lifting lug 38 extends through a slot 39 in the lid and is anchored (as will be described below) in the chamber 20 on the inside of the receptacle 12.

The base 16 is also flat, solid and circular in configuration. As best shown in figure 4, wear strips 40 of HDPE may be provided on a bottom face of the base 16. The wear strips allow for the intake 10 to be dragged into position without compromising the integrity of the intake 10.

The sidewall 18 is frusta-conical in configuration. As shown in figure 2, the lid 14, the sidewall 18, the base 16 and the mouth 28 are arranged in coaxial relationship with one another on a main axis 42 of the receptacle. As best shown in figures 2 and 3, the annular inlet 22 comprises a perforated region 8.1 of the sidewall 18. The region 18.1 comprises a plurality of spaced holes 44 through the sidewall. As best shown in figures 2 and 4, the holes 44 are defined towards a top region of the sidewall adjacent the lid and therefore the region 18.1 is also provided towards a top region of the sidewall. The perforated region 18.1 may typically be for about 80% from the top of the sidewall towards the bottom. A bottom region 18.2 of about 20% has no perforations.

The outlet 24 is in liquid flow communication with the inlet pipe section 26 via a conduit 46 comprising an elbow formation 48 and a straight section 50 extending to the outlet and beyond. The mouth 28 is arranged coaxially with the main axis 42 and is spaced from, but parallel to a top surface of the base 16. A clearance between the free end 30 and the base 16 may be in the order of 0.3D to 0.5D, where D is the diameter of the mouth 28. Any clearance to the sidewall 18 is preferably 0.75D as a minimum, noting that the D is a function of flow rate. In the embodiment shown, the inlet pipe section 26 is a flaring inlet pipe section, more particularly bell-shaped. The purpose of the bell-shaped inlet pipe section 26 is to reduce the velocities before entering the conduit 46. The inlet pipe section is of concentric conical shape with one end being the same size as the conduit

46 to which it is connected and the other being larger in diameter increasing over a calculated length. The diameter of the mouth 28 is flow dependant and may vary from design to design. In other embodiments (not shown) the inlet pipe section 26 may not be flaring, but of constant cross section.

The aforementioned lifting lug 38 is welded to the elbow formation 48 to aid in keeping the mouth 28 concentric.

A baffle arrangement 60 which is welded to a top surface of the base 16 extends upwardly towards the lid 14. The baffle arrangement 60 comprises at least a first elongate baffle member, preferably a plate 62 and a second elongate baffle member 64. The first and second plates are intersecting one another in an intersection region 66 which is in line with the main axis 42. Each of the at least first and second baffle plates define a plurality of spaced holes 68. In the example embodiment shown, the first and second baffle plates extend at 90° relative to one another.

Also, in the example embodiment shown, the baffle arrangement 60 extends beyond the free end 30 of the inlet pipe section 26 and into a region of the inlet pipe section towards the mouth 28. The baffle arrangement 60 is welded to the base 16 and to the inlet pipe section 26, to ensure that the clearance between the mouth 28 and base 16 is maintained. Hence, the inlet pipe section 26 is structurally supported and fixed in position by the baffle arrangement 60.

In other embodiments (not shown) the baffle arrangement may terminate short of the free end 30.

The straight section 50 of conduit 46 is provided, at a free end thereof with a backing flange 70 of galvanised mild steel or stainless steel. Two buoyancy compensators 72 are provided on the section 50 to compensate for the mass of the flange. Each compensator comprises an airtight enclosed half section of HDPE pipe attached by means of HDPE welding to the section 50. The buoyancy compensators are situated on section 50 directly opposite one another and at right angles relative to the main axis 42.

Radially spaced and inwardly extending braces 74 are provided on the inside of the sidewall 18. The braces are spaced evenly at 30° intervals along the entire circumference and extend the length of the sidewall, connecting the lid 14, the base 16 and the sidewall 18 to one another. The braces are HDPE welded to the lid, the base and the sidewall providing structural rigidity and to act as baffles to maintain uniform streamlined flow inside the chamber 20 and to discourage vortices formation. As best shown in figures 2 and 3, the intake 10 may also comprise an annular (preferably circular as in the embodiment shown) peripheral hoop 80 of HDPE, which may be hollow or filled with a suitable material, around a top end of the sidewall 18. The flat lid 14 may abut a top surface of the hoop. An annular (preferably circular as in the embodiment shown) skirt 82 of HDPE is provided to depend from the hoop 80. The skirt 82 provides a peripheral barrier between the inlet holes 44 of the sidewall 18 and the surface of the water, to prevent air entrained surface vortices from being pulled in. The hoop 80 provides structural support for the skirt 82, which may be attached thereto.

In use, the backing flange 70 is connected to the above suction hose which is connected to an inlet of the self-priming centrifugal pump. It is known that such a pump comprises an impeller comprising a plurality of radially extending vanes.

The intake 10 is floated in a body 90 (shown in figure 3) of water. The chamber 12 becomes flooded with water entering through the holes 44. Air accumulates at the underside of the lid 14 and is expelled through holes 44 in the sidewall beneath the skirt 82. When the pump is started and ramps up to speed, it creates a low pressure at an eye of the pump impeller. By virtue of the circular motion of the impeller rotating, liquid is flung around the outside of the impeller vane and causes a swirl or pre- rotation of the water prior to entering the pump. As the flow increases, so does the velocity in the suction hose. Liquid is drawn through the holes 44 in the sidewall. By increasing the cross-section sidewall area, flow is distributed linearly across these holes, while reducing the velocity and limiting excessive turbulence. The significant reduction in water velocity while water flow is divided linearly across the large number of holes, has a direct impact on lowering the critical submergence required above the mouth 28. The large number of adequately sized holes 44 disrupt and discourage the ingestion of surface air entrained vortices and acts as a strainer, preventing large solid floating debris from being pumped. The radially spaced braces 74 of the sidewall provide structural support and also act as an anti-rotation device, disrupting undesirable flow patterns to the enhanced vortices breakup. The skirt 82 prevents the holes 44 closer to the water surface 92, from drawing-in air, which aids in the disruption of vortices formation.

The bell-shaped inlet pipe section 26 at the centre of the intake 10 further reduces the velocities entering the suction hose and optimize flow streamlines into the suction hose. Any surface or structural entrained vortices entering the intake 10 are either broken down or collapsed by the holes 44 or by the baffle arrangement 60 (with adequately sized holes 68) which protrudes into and through the inlet pipe section 26 and mouth 28. The perforated baffle arrangement 60 inhibits swirl or pre-rotation flow patterns into the pump and creates laminar flow thus disrupting and discouraging vortices formation, allowing liquid to be drawn and streamlined efficiently into the mouth 28. The baffle arrangement 60 acts as an anti-rotational device, to streamline flow into the mouth 28 and breaking down and disrupt the formation of vortices prior to entering the lowered velocities at the mouth 28. The protrusion of the cross-member baffle arrangement 60 into the inlet pipe section 26 counteracts the swirl or pre-rotation effect caused by the centrifugal self-priming pump, by straightening the flow.

The solid base 16 prevents solids and floating debris from being sucked from below into the intake 10, when water levels are very low and close to the bottom of a dam. Water is effectively skimmed off the surface 92 of the dam and not drawn from below.

The lifting lug 38 is used to load or offload the intake 10 during transportation or packaging. It is also used to manoeuvre, raise, and lower the intake 10 into position on site. The positioning brackets 36 serve to aid on-site positioning to a fixed location or to another intake (not shown), or for general handling while on water or on land.

As stated above, the sidewall 18 is only perforated in the region 18.1 towards the top thereof. The bottom region 18.2 has no perforations to prevent sediment from entering the chamber 20 at low operating levels. The size of the perforations 44 in the sidewall 18 is based on the solids handling capabilities of the pump supplied and may vary from one intake 10 to another. The perforations 44 extend to underneath the skirt 82 allowing for the venting of air when the intake 10 is first placed in the water. The incoming flow is distributed linearly and uniformly across the holes 44 of the screened annular inlet substantially reducing the entrance velocity through each hole. Since minimum submergence is a function of entrance velocity, when utilising the intake, one could significantly reduce the minimum submergence required enabling the intake 10 to operate at extremely low levels.