GB2604335A

GB2604335A - Apparatus and Method for Forming a Suspensions of a Gas in a Liquid

Info

Publication number: GB2604335A
Application number: GB2102632.3A
Authority: GB
Inventors: O'Brien Cornelius
Original assignee: Cornelius Obrien
Current assignee: Cornelius Obrien
Priority date: 2021-02-24
Filing date: 2021-02-24
Publication date: 2022-09-07
Also published as: EP4274673A1; GB202102632D0; WO2022179953A1

Abstract

An apparatus for forming a stable suspension of sub-microscopic bubbles of gas in a liquid comprises a suspension-forming unit 4, the unit comprising a front plate 20 and rear plate 22 spaced from each other to define a spacing therebetween, an annular peripheral seal 26 within the spacing to define a sealed chamber 32, a fluid inlet 38, 40 and fluid outlet 42,44 in the front plate, and an eddy plate 46 mounted within the sealed chamber. The eddy plate comprises an inlet manifold 54 adjacent the fluid inlet, an outlet manifold 58 adjacent the fluid outlet and a plurality of parallel blind channels 60 in a surface of the plate extending from the inlet manifold to the outlet manifold. Each blind channel comprises a series of alternating projections in the form of a wave-shaped element such that a serpentine flow path is defined along the channel. A method of apparatus operation comprises pumping a liquid/gas mixture into the unit under pressure wherein as the mixture flows through each blind channel of the eddy plate, the series of eddy swirls forms a suspension of nanobubbles of the gas in the liquid.

Description

Apparatus and Method for Forming a Suspensions of a Gas in a Liquid Field of the Invention The present invention relates to an apparatus for forming a suspension of a gas in a liquid and to a method of forming a suspension of a gas in a liquid. In accordance with particular aspects of the present invention, the suspension which is formed comprises suspended gas which is in the form of nanobubbles in the liquid which remain stable within the liquid and do not vent out of the liquid.

Background of the Invention

It is known in the art to mix gas and liquid whereby the gas is suspended as nanobubbles within the liquid for a sustained period. The gas bubbles are of a size so small that they lack enough buoyancy to rise to the liquid surface but move, in a Brownian motion, randomly within the liquid and are dispersed uniformly throughout the liquid. The result is a uniform distribution of the suspended gas throughout the liquid.

The resulting gas/liquid mixture can be used for various applications, depending on the selected liquid/gas combination, for example: industrial cleaning, increase of yield in agriculture, improved water quality, enhancing biological activity in the body.

Traditional methods of mixing gas and liquid may produce microscopic gas bubbles, but these are not small enough to remain within the liquid, which thereby results in the gas eventually venting out of the liquid.

US-A-2020/0352016 discloses the production of a fluid suspension of nanoplasmoid gas bubbles. However, there is still a need for an improved apparatus, and associated method, for forming a suspension of a gas in a liquid.

The present invention aims at least partly to thin that need. Summary of the Invention The present invention provides an apparatus for forming a suspension of a gas in a liquid, the apparatus comprising a suspension-forming unit comprising: a front plate and a rear plate, the front and rear plates being spaced from each other to define a spacing therebetween, an annular peripheral seal located within the spacing between the front and rear plates, the annular peripheral seal being sealingly fitted to opposed inwardly facing surfaces of the front and rear plates to define a sealed chamber defined between opposed central portions of the front and rear plates which is surrounded by the annular peripheral seal, a fluid inlet on the front plate which has an entrance port which is in fluid communication with the sealed chamber, a fluid outlet on the front plate which has an exit port which is in fluid communication with the sealed chamber, wherein the entrance port and exit port are spaced from each other, and an eddy plate which is mounted within the sealed chamber between the front and rear plates, the eddy plate having opposite facing first and second surfaces which are respectively oriented towards the opposed inwardly facing surfaces of the front and rear plates, wherein the eddy plate comprises a first opening defining an inlet manifold which is adjacent to the entrance port, a second opening defining an outlet manifold which is adjacent to the exit port, and a plurality of blind channels in one of the first and second surfaces, the blind channels extending from the inlet manifold to the outlet manifold in a fluid flow direction within the sealed chamber between the fluid inlet and the fluid outlet, wherein each channel has a pair of first and second opposed longitudinal sidewalls and a floor which extend along the fluid flow direction, wherein the first and second longitudinal sidewalls are each provided with a series of alternating projections in the form of a wave-shaped element, adjacent projections defining a respective depression therebetween, wherein the projections of the each of first and second longitudinal sidewalls are respectively projected into the depressions of the other of the first and second longitudinal sidewalls to define a serpentine path for fluid flow along the channel between the inlet and outlet manifolds.

Preferred features of the apparatus of the present invention are defined in dependent claims 2 to 19.

The present invention further provides a method of forming a suspension of a gas in a liquid, the method comprising the steps of: providing an apparatus according to the present invention; (ii) pumping, by using the pump, the liquid/gas mixture into the suspension-forming unit via the at least one fluid inlet; (iii) flowing the liquid/gas mixture under the fluid pressure and at the flow rate through the channels whereby in each channel the projections form a sequential series of eddy swirls in the fluid flowing between the inlet and outlet manifolds thereby to form a suspension of nanobubbles of the gas within the liquid, wherein the nanobubbles have a maximum dimension of less than 1 micron; and (iv) collecting the suspension of the gas in the liquid at the at least one fluid outlet of the suspension-forming unit Preferred features of the method of the present invention are defined in dependent claims 21 to 25.

The apparatus of the preferred embodiments of the present invention can produce gas nanobubbles that are a formed in a vacuum and will remain suspended within the liquid for an extended period of time, typically up to 15 months The apparatus of the preferred embodiments of the present invention can produce gas nanobubbles, which have a maximum dimension of less than 1 micron, preferably a maximum dimension within the range of from 40 to 100 nm.

Such nanobubbles are Sub Microscopic Bubbles (SMB), and are of a size that can be absorbed on a cellular level into the human body if the liquid is consumed or in contact with the human body. Such absorption allows the fluid to be used as a delivery system to supply a gas, such as oxygen, directly into the blood supply of person, using a liquid such as water, for example, as the liquid medium to deliver the gas to the human body.

The apparatus of the preferred embodiments of the present invention provides a suspension-forming unit which is simple and inexpensive to manufacture, has few or no moving or consumable parts, and is expandable in flow rate capacity to suit the desired installation.

The suspension-forming unit of the preferred embodiments of the present invention unit is manufactured from a non-corrosive, food-safe material, for example stainless steel 316. The use of such a material not only increases the life span of the unit, but also complies with any legislation for food safety throughout the world.

The suspension-forming unit of the preferred embodiments of the present invention unit also has low maintenance, but is serviceable simply and inexpensively if/when required.

The suspension-forming unit of the preferred embodiments of the present invention can produce the desired gas nanobubbles suspended within the liquid consistently and reliably to produce a suspension of a gas in a liquid on a commercial scale, typically with nanobubbles stability lifetime having a tolerance of +/-10%.

The present invention is at least partly predicated on the technical feature that in fluid dynamics, when a flow of liquid (e.g. water) is passed over a specific object, an eddy may be formed. An eddy is a turbulent flow or swirling of fluid resulting in a reverse current. The suspension-forming unit of the preferred embodiments of the present invention comprises a series of wave shapes that generate an eddy.

The eddy generators are specifically shaped and positioned in the suspension-forming unit of the preferred embodiments of the present invention which achieves the result that the turbulent liquid becomes increasingly turbulent as the liquid passes through the unit. Since the liquid and the gas pass through the eddy generators simultaneously, the gas that is fed into the unit is stored within the bubbles which are created by the turbulent liquid.

The suspension-forming unit of the preferred embodiments of the present invention is designed so the eddy generators disrupt the liquid to the point that nanobubbles are formed under a negative pressure or a vacuum, and these nanobubbles can remain stored in suspension within the liquid for a significant period of time, typically up to 15 months.

Brief Description of the Drawings

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a schematic side view of an apparatus for forming a suspension of a gas in a liquid in accordance with a preferred embodiment of the present invention; Figure 2 is an exploded perspective view of the suspension-forming unit in the apparatus of Figure 1; Figure 3 is a side view of the suspension-forming unit shown in Figure 2, in assembled form; Figure 4 is a plan view of a first face of an eddy plate in the suspension-forming unit shown in Figure 2, the first face comprising channels; Figure 5 is an enlarged plan view of the circled highlighted area shown in Figure 4; Figure 6 is an enlarged plan view of the square highlighted area shown in Figure 4; Figure 7 is a plan view of a second face, opposite to the first face, of the eddy plate shown in Figure 4; Figure 8 is an enlarged cross-section on line A in Figure 4; and Figure 9 is an exploded perspective view of a suspension-forming unit in the apparatus of Figure 1 in accordance with a further preferred embodiment of the present invention

Detailed Description of the Invention

Referring to Figures Ito 8, there is shown an apparatus, designated generally as 2, for forming a suspension of a gas in a liquid in accordance with a preferred embodiment of the present invention.

The apparatus 2 comprises a suspension-forming unit 4. There are also provided a first tank 6 for holding a supply of liquid and a second tank 8 for holding a supply of gas. A mixing valve 10 is fluidically coupled by respective fluid conduits 7, 9 to the first and second tanks 6, 8 for mixing together liquid and gas from the first and second tanks 6, 8 to form a liquid/gas mixture. A pump 12 is fluidically coupled by a fluid conduit 13 to the mixing valve 10, and by a fluid conduit 14 to at least one fluid inlet 38 of the suspension-forming unit 4. The pump 12, in use, pumps the liquid/gas mixture into the suspension-forming unit 4 to form suspension of the gas in the liquid.

In the preferred embodiment of the present invention, the pump 12 is configured to pump the liquid/gas mixture into the suspension-forming unit 4 at a fluid pressure within the range of from 300,000 to 700,000 Pascals (3 to 7 Bar) and at a flow rate within the range of from 10 to 15 litres/minute.

The resultant suspension of the gas in the liquid exits the suspension-forming unit 4 via at least one fluid outlet 42, and flows along a fluid conduit 15 to a packaging or storage station (not shown).

Referring in particular to Figures 2 and 3, the suspension-forming unit 4 comprises a front plate 20 and a rear plate 22. The front and rear plates 20, 22 are spaced from each other to define a spacing 24 therebetween. An annular peripheral seal 26 is located within the spacing 24 between the front and rear plates 20, 22. The annular peripheral seal 26 is sealingly fitted to opposed inwardly facing surfaces 28, 30 of the front and rear plates 20, 22 to define a sealed chamber 32, between opposed central portions 34, 36 of the front and rear plates 20, 22, which is surrounded by the annular peripheral seal 26.

At least one fluid inlet 38 is provided on the front plate 20 which has an entrance port 40 which is in fluid communication with the sealed chamber 32. At least one fluid outlet 42 on the front plate 20 has an exit port 44 which is in fluid communication with the sealed chamber 32.

The fluid inlet and outlet 38, 42 are preferably configured to be connectable to standard fittings commonly used in the industry to enable simple installation to existing infrastructure. The fluid inlet and outlet connections are compatible with standard connectors that are widely available in commerce.

The entrance and exit port(s) 40, 44 are spaced from each other. In the illustrated embodiment, the front plate 20 is provided with a plurality of the fluid inlets 38, in particular two fluid inlets 38, which are spaced from each other in the width direction of the front plate 20 and a plurality of the fluid outlets 42, in particular two fluid outlets 42, which are spaced from each other in the width direction of the front plate 20.

In alternative embodiments, only one fluid inlet 38 and only one fluid outlet 42 are provided on the front plate 20, or more than two fluid inlets 38 and more than two fluid outlets 42 are provided on the front plate 20.

Referring additionally to Figures 4 to 8, the suspension-forming unit 4 further comprises at least one eddy plate 46 which is mounted within the sealed chamber 32 between the front and rear plates 20, 22. The eddy plate 46 has opposite facing first and second surfaces 48, 50 which are respectively oriented towards the opposed inwardly facing surfaces 28, 30 of the front and rear plates 20, 22.

The eddy plate 46 comprises a first opening 52 defining an inlet manifold 54 which is adjacent to the entrance port 40, a second opening 56 defining an outlet manifold 58 which is adjacent to the exit port 44, and a plurality of blind channels 60 in one of the first and second surfaces 48, 50. The plurality of blind channels 60 are parallel to each other.

The blind channels 60 do not extend through the entire thickness of the eddy plate 46 and leave a solid continuous surface 47 on the reverse side of the eddy plate 46, which in the illustrated embodiment is the second surface 50 since the blind channels 60 extend into the thickness of the eddy plate 46 from the first surface 48 In the illustrated embodiment the plurality of blind channels 60 are provided in the first surface 48 of the eddy plate 46 which is oriented towards the inwardly facing surface 28 of the front plate 20. However, alternatively the plurality of blind channels 60 may be provided in the second surface 50 of the eddy plate 46 which is oriented towards the inwardly facing surface 30 of the rear plate 22.

In the illustrated embodiment, the first and second openings 52, 56 extend wholly through a thickness of the eddy plate 46 In the illustrated embodiment, the first and second openings 52, 56 are substantially rectangular in plan, and optionally with rounded ends as shown. The first and second openings 52, 56 extend transversely across a portion of the width of the eddy plate 46, and when the front plate 20 is provided with a plurality of the fluid inlets 38 which are spaced from each other in the width direction and a plurality of the fluid outlets 40 which are spaced from each other in the width direction, the first and second openings 52, 56 are respectively adjacent to the fluid inlets 38 and fluid outlets 40.

The blind channels 60 extend from the inlet manifold 54 to the outlet manifold 58 in a fluid flow direction (F) within the sealed chamber 32 between the fluid inlet 38 and the fluid outlet 42.

Each channel 60 has a pair of first and second opposed longitudinal sidewalls 62, 64 and a floor 65 which extend along the fluid flow direction (F). In the illustrated embodiment, each of the blind channels 60 has a width within the range of from 4 to 10 mm, a depth of from 10 to 25 mm and a length of from 100 to 300 mm, for example 200mm.

The first and second longitudinal sidewalk 62, 64 are each provided with a series of alternating projections 66, with adjacent projections 66 defining a respective depression 68 therebetween. Typically, each depression 68 comprises a central part 69 of the depression 68 which is formed by a planar portion of the sidewall 62, 64 which is aligned along the fluid flow direction (F) The projections 66 of the each of first and second longitudinal sidewalls 62, 64 are respectively projected into the depressions 68 of the other of the first and second longitudinal sidewalls 62, 64 to define a serpentine path 70 for fluid flow along the channel 60 between the inlet and outlet manifolds 54, 58.

In the illustrated embodiment, each of the projections 66 has a shape, when viewed along a direction orthogonal to the eddy plate 46, in the form of a curved wave-shaped element 61, having opposite curved faces 63, 65, comprising a convex face 63 and a concave face 65, converging to a wave peak 67.

In each channel 60, for each projection 66 of a series of the projections 66 extending along the channel 60, the projection 60 has a bent tip portion 72 which has a pointed free end 74 which is oriented towards the inlet manifold 54 in a direction opposite to the fluid flow direction (F) The bent tip portion 72 has a curved inner concave surface 76 which faces towards the inlet manifold 54 in a direction opposite to the fluid flow direction (F). The curved inner concave surface 76 is shaped and dimensioned to constitute a vortex-forming surface which generates an eddy swirl in fluid flowing along the channel 60 in the fluid flow direction (F). The bent tip portion 72 also has a curved outer convex surface 78 which faces towards the outlet manifold 58 in the fluid flow direction (F).

Typically, in at least one, or optionally both, of the first and second opposed longitudinal sidewalls 62, 64, each of the projections 66 has a respective bent tip portion 72.

In the illustrated embodiment, in the first longitudinal sidewall 62 each of the projections 66 has a respective bent tip portion 72, whereas each of the projections 66 of the second longitudinal sidewall 64 has a different structure.

In particular, each of the projections 66 of the second longitudinal sidewall 64 has a curved outer convex surface 80 which faces towards the inlet manifold 54 in a direction opposite to the fluid flow direction (F) and a curved outer concave surface 82 which faces towards the outlet manifold 58 in the fluid flow direction (F). A free end 83 is blunt as compared to the pointed free end 74 of the bent tip portion 72, and is oriented towards the outlet manifold 58 in the fluid flow direction (F).

In one embodiment as shown in Figures 2 and 3, the suspension-forming unit 4 comprises only a single eddy plate 46 which is mounted within the sealed chamber 32 between the front and rear plates 20, 22. The first, i.e. front and second i.e. rear surfaces 48, 50 of the eddy plate 46 are respectively separated from the front and rear plates 20, 22 by a respective seal member 84 comprised in the annular peripheral seal 26.

Typically, the inwardly facing surfaces 28, 30 of the front and rear plates 20, 22, and the opposite facing first and second surfaces 48, 50 of the eddy plate 46 are each provided with a peripheral groove 85 for receiving an annular edge of a respective seal member 84 of the annular peripheral seal 26.

However, in the illustrated embodiment of Figure 9, the suspension-forming unit 4 may comprise a plurality of the eddy plates 46 which are mounted in parallel within the sealed chamber 32 between the front and rear plates 20, 22. Adjacent eddy plates 46 are separated by a respective seal member 84 comprised in the annular peripheral seal 26.

The first and second openings 52, 56 in an eddy plate 46 which is rearwardly mounted, with respect to the front plate 20, relative to an adjacent eddy plate 46 are in fluid communication with, and aligned with, the first and second openings 52, 56 of the adjacent eddy plate 46. The aligned first and second openings 52, 56 allow for the liquid/gas mixture to flow downwardly towards the rearmost eddy plate 46 and to flow laterally along the channels 60 of each eddy plate 46 prior to exiting the sealed chamber 32 through the fluid outlet(s) 42 When multiple eddy plates 46 are installed, the blind channels 60 of adjacent eddy plates 46 face the same direction, i.e. towards the front plate 20 or the rear plate 22. The blind channels 60 of adjacent eddy plates 46 are separated by the solid continuous surface 47 on the reverse side of the eddy plates 46. This provides that each eddy plate 46 functions independently to form a proportion of the total nanobubbles which are produced.

The frontmost and rearmost eddy plates 46 of the plurality of eddy plates 46 are respectively separated from the front and rear plates 20, 22 by a respective seal member 84 comprised in the annular peripheral seal 26.

The suspension-forming unit 4 further comprises a clamping mechanism 86 for clamping together the front and rear plates 20, 22, and the one or more eddy plates 46 and annular peripheral seal 26 therebetween. Typically, the clamping mechanism comprises an annular array of clamp elements 88, such as bolts and associated nuts, which extend through holes 91 in peripheral edges 90 of the front and rear plates 20, 22 and holes 93 in peripheral edges 92 of the one or more eddy plates 46 The annular peripheral seal 26 is located inwardly of the peripheral edges 90 of the front and rear plates 20, 22 and peripheral edges 92 of the one or more eddy plates 46. The clamp elements 88 are typically made from stainless steel.

The clamping mechanism 86 can readily be removed to enable the number of eddy plates 46 within the suspension-forming unit 4 to be varied as desired to be able to modify the flow rate capacity of the suspension-forming unit 4.

The thickness of the front and rear plates 20, 22, and the eddy plate(s) 46, which are typically composed of stainless steel, are selected so as to prevent any deformation or warping during service in order to ensure a secure seal with the adjacent plate(s) follow plate.

The suspension-forming unit 4 is typically operated at ambient temperature, and the ambient temperature may vary, for example, between 10 and 50 °C, depending upon climactic or production facility conditions. The suspension-forming unit 4 is constructed to maintain its integrity and performance over such a temperature range The suspension-forming unit 4 of the preferred embodiments of the present invention is compact in size and can be mounted any reasonable distance from the pump 12. The suspension-forming unit 4 is made from a material that can withstand the high pressure from the liquid and be resistant from any corrosion from and liquid and gas that may be process within the unit. Stainless steel is the ideal material as it exceeds these requirements and is also relatively economical to manufacture.

The seals with the suspension-forming unit 4 are selected from a material which is resistant to damage from the liquid and gas but also suitable for the desired application, for example, if used for the beverage industry they must be made from a food safe material.

The suspension-forming unit 4 is configured to require minimal servicing, and has no moving parts.

Only liquid filtered for particulates and debris should be used to avoid damage and build of silt. Nevertheless, it would be possible to clean the suspension-forming unit 4 using the standard Clean In Place (C1P) methods of current liquid handling industries.

The apparatus of the present invention is used in a method of forming a suspension of a gas in a liquid.

The method comprises providing the apparatus as described above. Also provided are the desired liquid and gas to be mixed and formed into the suspension which are held in the first and second tanks 6, 8 respectively. The fluid outlets of the first tank 6 and the second tank 8, and the mixing valve 10, are configured to provide a desired weight ratio between the liquid and gas to be mixed. The mixing valve 10 preferably comprises a venturi valve which draws a flow of gas, at a desired gas flow rate, into the flow of liquid, at a desired liquid flow rate, thereby to form the mixture of the liquid and gas at the desired volume ratio Typically, the liquid/gas mixture comprises from 85 to 95 vol% liquid and from 5 to 15 vol% gas, for example 90 vol% liquid and 10 vol% gas, each based on the total volume of the liquid/gas mixture (the volumes being measured at atmospheric pressure (1 Bar) and at 20 °C).

The liquid and gas may comprise any desired materials to be mixed. However, preferably the liquid comprises water and the gas comprises oxygen.

The liquid is fed via an input line 3 into the first tank 6 automatically via a valve 5 to ensure that the first tank 6 has a consistent supply of liquid. The infeed flow rate exceeds the outflow rate from the first tank 6 to ensure that the first tank 6 does not drain fully of liquid. The source liquid is preferably filtered for particulates with a suitable filter (not shown) and if used for human consumption, then a UV filter (not shown) should also be installed. The first tank 6 typically has a volume which has a ratio of approximately 10:1 relative to the outflow rate. The outflow rate is determined by the number of eddy plates 46 that are installed in the unit 4 and the capacity of the high-pressure pump 12. For example, if five eddy plates 46 are installed and the flow rate is set for approximately 50 litres per minute, the first tank 6 should have a capacity of at least 500 litres.

Liquid is drawn from the first tank 6 holding the liquid 1 by the pump 12. As the liquid passes through the liquid/gas mixing valve 10, gas is drawn from the second tank 8 holding the gas, and drawn through the pump 12. The mixture of liquid to gas is set to a pre-determined ratio to avoid cavitation in the pump 12, and to provide a desired concentration of gas in the liquid.

The desired gas is fed via an inlet line 17 into the second tank 8. This can be done by several ways depending on the desired gas. For example, a gas generator can be used to generate the desired gas or a high-pressure prefilled gas bottle can be used. In either case, the feed into the second tank 8 of holding the gas is equal to or slightly exceeds the amount of gas drawn into the liquid/gas mixing valve 10, and is of consistent flow.

The liquid and gas mixture is then passed through the suspension-forming unit 4 via the pump 12. The final processed liquid/gas suspension is then outputted into the desired downstream infrastructure, such as a packaging line.

The liquid/gas mixture is pumped, using the pump 12, into the suspension-forming unit 4 via the at least one fluid inlet 38. Typically, the fluid pressure is within the range of from 300,000 to 700,000 Pascals (3 to 7 Bar) and the fluid flow rate is within the range of from 10 to 15 litres/second per unit This pumping is followed by the step of flowing the liquid/gas mixture under the fluid pressure and at the flow rate through the channels 60, whereby in each channel 60 the projections 66 form a sequential series of eddy swirls in the fluid flowing between the inlet and outlet manifolds 54, 58 thereby to form a suspension of nanobubbles of the gas within the liquid The nanobubbles have a maximum dimension of less than 1 micron, preferably a maximum dimension within the range of from 40 to 100 nm The process within the suspension-forming unit 4 to create these bubbles requires the liquid and gas to be pumped though the sealed chamber by a high-pressure pump. As the mixture passes along the channels 60 of the at least one eddy plate 46, the gas/liquid mixture is continuously disturbed resulting in the creation of the sub microscopic nanobubbles. This eddy plate 46 is the 'working' plate which creates turbulence in the liquid to form the desired nanobubbl es.

The first, upstream, manifold 54 receives the liquid and gas mixture under high pressure from the entrance ports 44. The liquid and gas mixture is then forced along the channels 60. The channels 60 comprise the series of projections 66, defining curved wave-shaped elements 61. The bent tip portions 72, which have the pointed free end 74 and the curved inner concave surface 76, force the flowing mixture to reverse on itself creating an eddy swirl. As the liquid and gas mixture travels along the channels 60, each bent tip portion 72 forces another eddy swirl to be created, thereby increasing the turbulence and creating the nanobubbles. The process liquid then enters the second, downstream, manifold 58 and is forced outwardly through the exit ports 44.

To maintain the gas/liquid mixture, the gas -bubble" must be sub microscopic in size, i.e. a nanobubble having a maximum dimension which is less than 1 micron, that is too small to have enough buoyancy to naturally rise in the liquid; therefore the bubble is suspended in the liquid and travels in a random motion within the liquid by Brownian motion. The gas bubbles are uniformly dispersed throughout the liquid.

It is to be noted that the apparatus does not require any external electrical power to operate the suspension-forming unit 4, with the exception that the pump 12 is typically an electric pump requiring external electrical power.

Finally, the suspension of the gas in the liquid is collected downstream of the at least one fluid outlet of the suspension-forming unit. Typically, thereafter the collected suspension of the gas in the liquid is packaged into bottles at ambient atmospheric pressure The resultant process liquid, which comprises the suspension of the gas in the liquid in the form of nanobubbl es, may then be used in a number of desired applications In one preferred embodiment, the water is drinking water for human consumption and the suspension of oxygen in water comprises a beverage. The beverage has a high oxygen content, which is beneficial to human health In one preferred embodiment, the process fluid may be used in horticulture, in particular hydroponics. If the liquid processed is water and the gas process is oxygen the final product is to be used in the horticulture industry, for example hydroponics, oxygen-rich water yields improved plant quality and/or growth, and/ or improved crop yield. Traditional hydroponic methods do not necessarily provide oxygen in the form of suspended nanobubbles which is absorbed more efficiently into the plant. Processed water produced by the method and apparatus of the present invention may be stored for long periods of time in a suitable container, for example to exhibit a shelf life of up to 15 months when stored as a beverage in a conventional blow-moulded bottle composed of polyethylene terephthalate (PET), and still maintain its high oxygen content making it far more effective for large commercial growers but also accessible to smaller hobby horticulture enthusiasts.

Claims

Claims 1 An apparatus for forming a suspension of a gas in a liquid, the apparatus comprising a suspension-forming unit comprising: a front plate and a rear plate, the front and rear plates being spaced from each other to define a spacing therebetween, an annular peripheral seal located within the spacing between the front and rear plates, the annular peripheral seal being sealingly fitted to opposed inwardly facing surfaces of the front and rear plates to define a sealed chamber defined between opposed central portions of the front and rear plates which is surrounded by the annular peripheral seal, a fluid inlet on the front plate which has an entrance port which is in fluid communication with the sealed chamber, a fluid outlet on the front plate which has an exit port which is in fluid communication with the sealed chamber, wherein the entrance port and exit port are spaced from each other, and an eddy plate which is mounted within the sealed chamber between the front and rear plates, the eddy plate having opposite facing first and second surfaces which are respectively oriented towards the opposed inwardly facing surfaces of the front and rear plates, wherein the eddy plate comprises a first opening defining an inlet manifold which is adjacent to the entrance port, a second opening defining an outlet manifold which is adjacent to the exit port, and a plurality of blind channels in one of the first and second surfaces, the blind channels extending from the inlet manifold to the outlet manifold in a fluid flow direction within the sealed chamber between the fluid inlet and the fluid outlet, wherein each channel has a pair of first and second opposed longitudinal sidewalls and a floor which extend along the fluid flow direction, wherein the first and second longitudinal sidewalls are each provided with a series of alternating projections in the form of a wave-shaped element, adjacent projections defining a respective depression therebetween, wherein the projections of the each of first and second longitudinal sidewalls are respectively projected into the depressions of the other of the first and second longitudinal sidewalls to define a serpentine path for fluid flow along the channel between the inlet and outlet manifolds.
2. An apparatus according to claim 1 wherein in each channel, for each projection of a series of the projections extending along the channel, the projection has a bent tip portion which has a pointed free end which is oriented towards the inlet manifold in a direction opposite to the fluid flow direction.
3. An apparatus according to claim 2 wherein the bent tip portion has a curved inner concave surface which faces towards the inlet manifold in a direction opposite to the fluid flow direction.
4. An apparatus according to claim 3 wherein the curved inner concave surface is shaped and dimensioned to constitute a vortex-forming surface which generates an eddy swirl in fluid flowing along the channel in the fluid flow direction.
5. An apparatus according to any one of claims 2 to 4 wherein the bent tip portion has a curved outer convex surface which faces towards the outlet manifold in the fluid flow direction.
6. An apparatus according to any one of claims 2 to 5 wherein each of the projections of at least one of the first and second opposed longitudinal sidewalls has a respective bent tip portion.
7. An apparatus according to claim 6 wherein each of the projections of the first longitudinal sidewall has a respective bent tip portion and each of the projections of the second longitudinal sidewall has a curved outer convex surface which faces towards the inlet manifold in a direction opposite to the fluid flow direction and a curved outer concave surface which faces towards the outlet manifold in the fluid flow direction.
8. An apparatus according to any one of claims 1 to 7 wherein each depression comprises a central part of the depression which is formed by a planar portion of the sidewall which is aligned along the fluid flow direction.
9. An apparatus according to any one of claims 1 to 8 wherein the plurality of blind channels are parallel to each other.
An apparatus according to any one of claims 1 to 9 wherein the plurality of blind channels are provided in the first surface of the eddy plate which is oriented towards the inwardly facing surface of the front plate.
11 An apparatus according to any one of claims 1 to 10 wherein the first and second openings extend wholly through a thickness of the eddy plate.
12 An apparatus according to any one of claims 1 to 11 wherein the first and second openings extend transversely across a portion of the width of the eddy plate, and the front plate is provided with a plurality of the fluid inlets which are spaced from each other in the width direction and a plurality of the fluid outlets which are spaced from each other in the width direction.
13 An apparatus according to any one of claims Ito 12 wherein each of the blind channels has a width within the range of from 4 to 10 mm, a depth within the range of from 10 to 25 mm and a length within the range of from 100 to 300 mm 14 An apparatus according to any one of claims 1 to 13 wherein the suspension-forming unit comprises a plurality of the eddy plates, wherein the eddy plates are mounted in parallel within the sealed chamber between the front and rear plates, and wherein adjacent eddy plates are separated by a respective seal member comprised in the annular peripheral seal, and wherein the first and second openings in an eddy plate which is rearwardly mounted, with respect to the front plate, relative to an adjacent eddy plate are in fluid communication with the first and second openings of the adjacent eddy plate An apparatus according to claim 14 wherein the frontmost and rearmost eddy plates of the plurality of eddy plates are respectively separated from the front and rear plates by a respective seal member comprised in the annular peripheral seal.16 An apparatus according to any one of claims 1 to 15 wherein the suspension-forming unit further comprises a clamping mechanism for clamping together the front and rear plates, and the one or more eddy plates and annular peripheral seal therebetween.17 An apparatus according to claim 16 wherein the clamping mechanism comprises an annular array of clamp elements which extend though peripheral edges of the front and rear plates and peripheral edges of the one or more eddy plates, the annular peripheral seal being located inwardly of the peripheral edges of the front and rear plates and peripheral edges of the one or more eddy plates.18 An apparatus according to any one of claims 1 to 17 further comprising a first tank for holding a supply of liquid, a second tank for holding a supply of gas, a mixing valve, optionally a venturi valve, fluidically coupled to the first and second tanks for mixing together liquid and gas from the first and second tanks to form a liquid/gas mixture, and a pump fluidically coupled to the mixing valve and to the at least one fluid inlet of the suspension-forming unit for pumping the liquid/gas mixture into the suspension-forming unit to forming a suspension of the gas in the liquid.19 An apparatus according to claim 18 wherein the pump is configured to pump the liquid/gas mixture into the suspension-forming unit at a fluid pressure within the range of from 300,000 to 700,000 Pascals and at a flow rate within the range of from10 to 15 litres/minute per unit 20. A method of forming a suspension of a gas in a liquid, the method comprising the steps of: (i) providing an apparatus according to claim 18 or claim 19; (ii) pumping, by using the pump, the liquid/gas mixture into the suspension-forming unit via the at least one fluid inlet, optionally at a fluid pressure within the range of from 300,000 to 700,000 Pascals and at a flow rate within the range of from 10 to 15 litres/minute per unit; (Hi) flowing the liquid/gas mixture under the fluid pressure and at the flow rate through the channels whereby in each channel the projections form a sequential series of eddy swirls in the fluid flowing between the inlet and outlet manifolds thereby to form a suspension of nanobubbles of the gas within the liquid, wherein the nanobubbles have a maximum dimension of less than 1 micron; and (iv) collecting the suspension of the gas in the liquid downstream of the at least one fluid outlet of the suspension-forming unit, 21 A method according to claim 20 wherein the liquid/gas mixture comprises from 85 to 95 vol% liquid and from 5 to 15 vol% gas, each based on the total volume of the liquid/gas mixture, and the volumes being measured at atmospheric pressure (1 Bar) and at 20 °C.22 A method according to claim 20 or claim 21 wherein the nanobubbles have a maximum dimension within the range of from 40 to 100 nm.23 A method according to any one of claims 20 to 22 wherein the liquid comprises water and the gas comprises oxygen.24 A method according to claim 23 wherein the water is drinking water for human consumption and the suspension of oxygen in water comprises a beverage A method according to any one of claims 20 to 24 further comprising the step (v), after step (iv) of packaging the collected suspension of the gas in the liquid into bottles at ambient atmospheric pressure.