WO2018100553A1

WO2018100553A1 - Apparatus and method for producing and dispersing nano-sized structures

Info

Publication number: WO2018100553A1
Application number: PCT/IB2017/057582
Authority: WO
Inventors: Don Edward Kress; Kamalul Arifin Yusof
Original assignee: Cetamax Ventures Ltd.
Priority date: 2016-12-01
Filing date: 2017-12-01
Publication date: 2018-06-07

Abstract

Provided are devices, systems and methods for generating and dispersing nano-sized structures, such as nano bubbles. A vortex reactor (300) has a reactor body (308) with a first end(304) and second end (306). An inlet port (302) at the first end (304) directs a fluid into the reactor body (308) where it moves toward the second end (306). A vortex induction mechanism (132) is positioned within the reactor body (308) and includes a plurality of angled fights to induce vertical motion within the moving fluid. A section of the vortex induction mechanism (132) is surrounded by a porous element (150). A gas is passed through the porous element (150) so that nano-sized structures, such as nanobubbles, form on the inner surface of the porous element (150). The vertical motion of the fluid aids in shearing off the forming nano-sized structures, such as nanobubbles, so to generate nano-sized structures, such as nanobubbles, of small size and narrow size distribution.

Description

APPARATUS AND METHOD FOR PRODUCING AND

DISPERSING NANO-SIZED STRUCTURES

BACKGROUND

[0001] The present disclosure relates generally to devices, systems, and methods for producing and dispersing nano-sized structures such as nanobubbles. In particular, the present disclosure describes embodiments which utilize one or more vortex reactors configured to generate vortical fluid flows in combination with nanobubble generation.

[0002] Sparging technology is widely utilized in gas-liquid contacting applications. Typically, a pressurized gas is forced through a network of pores within a porous metal or ceramic sparging device to form a supply of bubbles within the contacted liquid. By introducing the gas into the liquid in the form of a multitude of bubbles, the surface area available for mass transfer, heat transfer, and chemical interaction between the contacted gas and liquid phases is increased. Smaller bubbles have a higher surface area to volume ratio and are therefore typically desirable to aid in more complete and/or more rapid processing. However, the generation of progressively smaller bubbles is correlated with higher equipment costs and higher overall processing costs. In addition, it becomes increasingly challenging to manage bubble size and bubble size distribution as target bubble size decreases.

BRIEF SUMMARY

The present disclosure relates to devices, systems, and methods for generating and dispersing nano-sized structures such as nanobubbles. In certain embodiments, a vortex reactor has a reactor body with a first end and second end. An inlet port at the first end directs a fluid into the reactor body where it moves toward the second end. A vortex induction mechanism is positioned within the reactor body and includes a plurality of angled flights to induce vortical motion within the moving fluid. At least a portion of the vortex induction mechanism is surrounded by a porous element. The porous element is configured to pass a pressurized gas from an outer side through to an inner surface so that bubbles begin to form on the inner surface. The vortical motion of the fluid passing through the reactor body and contacting the inner surface of the porous element aids in shearing off the forming bubbles to generate nanobubbles of smaller size and/or narrower size distribution within the fluid.

[0003] In some embodiments, the vortex induction mechanism includes a section disposed upstream of the porous element having angled flights configured to progressively increase the angular velocity of the passing fluid. In preferred embodiments, the section of the vortex induction mechanism coinciding with the porous element has angled flights of substantially consistent angle and pitch. This results in fluid flow of consistent angular velocity across the area of the porous element which enables the passing fluid contacting the inner surface of the porous element to maintain a consistent and controlled shear force, resulting in nanobubbles of narrow size distribution.

[0004] At high flow rates, cavitation can occur in a turbulent shear flow region due to local pressure reductions in the intense turbulent eddies. Certain embodiments described herein enable this form of cavitation within a flow regime that is vortical, providing for bubble growth and collapse that occurs within the fluid medium and not near the surfaces of the apparatus. A radial pressure gradient is created by the vortical movement of the fluid in which the pressure is lower at or near the axis of rotation as compared to locations further out from the axis. Cavitation bubbles will preferentially form in this lower pressure region, then collapse as the influence of the intense turbulent eddies wanes and the fluid flows downstream. The beneficial physical and chemical aspects of cavitation can therefore be exploited within a controlled volume and with minimal cavitation induced erosion damage to the apparatus.

[0005] In some embodiments, a magnetic element surrounds at least a portion of the porous element. The magnetic element includes one or more magnets positioned to generate a magnetic field such that a resulting Lorentz force is directed radially inward toward an axis of the reactor body to aid in detaching the bubbles forming on the inner surface of the porous element.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] To further clarify the above and other advantages and features of the present disclosure, a more particular description of the disclosure will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. It is appreciated that these drawings depict only illustrated embodiments of the disclosure and are therefore not to be considered limiting of its scope. Embodiments of the disclosure will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:

[0007] Figure 1 illustrates an exemplary embodiment of a reactor configured to induce vortical flow of a reactor fluid;

[0008] Figures 2A and 2B illustrate exemplary embodiments of vortex induction mechanisms which may be utilized in a vortex reactor; [0009] Figures 3A through 3C illustrate an exemplary embodiment of a reactor configured to produce vortical flow in two separate fluids before mixing the two fluids;

[0010] Figures 4 through 6 illustrate various embodiments of vortex reactors configured to generate nanobubbles; and

[0011] Figure 7 illustrates an exemplary downstream vortex reactor configured to utilize a density gradient to separate generated nanobubbles by size.

DETAILED DESCRIPTION

Introduction

[0012] The present disclosure relates to the production of nanobubbles and microbubbles in a size range beneficial for use in a variety of physical and/or chemical reactions, including bubbles having average sizes of about 5 nm or more to about 50 μπι or less. In particular, the present disclosure describes embodiments which produce such nanobubbles/microbubbles using one or more vortex reactors which generate vortical fluid flow to effectively provide the nanobubbles/microbubbles.

[0013] The term "nanobubbles" is used herein to refer to bubbles having average sizes of about 5 nm or more to about 50 μπι or less, unless a more specific size range is given. For simplicity, the term "nanobubbles" will be understood to refer to such bubbles even though it will be understood that some bubbles having μπι level diameters are included within the term.

[0014] One or more of the described embodiments are also able to produce nanobubbles having a narrow size distribution. For example, some embodiments are configured to generate nanobubbles wherein at least about 75%, 80%>, 85%>, 90%, 95%, or 99% of produced bubbles have a size within about 30%, 25%, 20%, 15%, 10%, 5%, or 1% of the average nanobubble size.

[0015] Nanobubbles produced using the described embodiments provide a variety of benefits and may be used in a variety of applications. The implosive collapse of nanobubbles in a liquid can result in extreme local conditions (e.g., high temperatures and pressures) at and near the collapsing bubble. These conditions can initiate or augment physical and/or chemical effects within the fluid, such as increased physical breakdown of components within the liquid and/or increased chemical reactivity.

[0016] In addition, nanobubbles have an extremely high surface area to volume ratio that allows for efficient use in gas-liquid contacting applications. With nanobubbles, the surface area available for mass transfer, heat transfer, and chemical interaction between the contacted gas and liquid phases is increased, and aids in more complete or more rapid processing. Further, nanobubbles of particular sizes and size distributions have been shown to be capable of penetrating cells, and this effect could be utilized in targeted drug delivery applications.

[0017] The nanobubble producing embodiments described herein may be utilized in, for example, sterilization and cleaning applications, bioprocessing applications (e.g., fermentation processes, bioreactor cell culture, biomass production processes, microalgae production), water treatment applications (e.g., froth flotation, flocculation, aeration to satisfy biological oxygen demand, ozonation), chemical processing, aquaculture, dissolving a gas stream in a liquid (e.g., adding nitrogen bubbles to liquid to displace dissolved oxygen).

[0018] Although preferred vortex reactor embodiments for generating nanobubbles are described herein, other exemplary vortex reactor configurations which may be utilized to effectively generate nanobubbles are described in U.S. Patent Application No. 15/170,298, which is incorporated herein by reference in its entirety.

[0019] Further, although the reactor embodiments are described herein in the context of generating and dispersing nanobubbles, it will be understood that the disclosed devices, systems, and methods may also be utilized for generating and/or dispersing other nano- sized structures, such as nano-sized solids and nano-sized emulsion droplets. For example, embodiments described herein may be modified so as pass an injection fluid rather than a gas through the porous element and into the reactor. The injection fluid passed through the porous element may be immiscible with the fluid to which it is contacted within the reactor. The reactor may beneficially function to shear off and disperse nano-sized droplets of the injection fluid. The reactor may also function to fracture clusters of nano- sized solids if they are present and if such fracturing is desired. In some embodiments, the injection fluid may be an emulsion itself. For example, the injection fluid may be a water- in-oil emulsion, and the fluid within the reactor to which the injection fluid is contacted may be water, resulting in a water-in-oil-in-water ("WOW") emulsion.

Overview of Vortex Reactor Configurations

[0020] Figure 1 illustrates an exemplary embodiment of a vortex reactor 300 which includes a vortex induction mechanism configured to form or augment one or more vortices within the reactor. Figure 1 illustrates an embodiment of a reactor 300 having a reactor body 308, an inlet port 302 for conducting a reactor fluid into the reactor body 308, and an induction mechanism 332 positioned within the reactor body 308 and configured to contact reactor fluid to induce vortical motion in the reactor fluid as it passes through the induction mechanism 332.

[0021] In the illustrated embodiment, inlet port 302 is disposed so as to deliver a reactor fluid into reactor body 308 upstream from induction mechanism 332 (i.e., to deliver a reactor fluid at a point between a first end 304 and the flights of the induction mechanism 332). Induction mechanism 332 is preferably disposed along a longitudinal length of reactor body 308 sufficient to induce a desired level of vortical motion in the reactor fluid. During operation, a reactor fluid is passed into reactor body 308 through inlet port 302, where it is contacted with induction mechanism 332. As pressure drives the fluid through induction mechanism 332 and toward second end 306, the geometric configuration of induction mechanism 332 causes or augments vortical flow within the reactor fluid.

[0022] The induction mechanism 332 may be configured according to various operational parameters (e.g., fluid flow rate, fluid pressure, size and shape of reactor body, type of fluid, etc.) to provide a desired level of vortical flow to the reactor fluid. In some embodiments, an induction mechanism has a cross-sectional diameter that is substantially equal to the inner diameter of a reactor body. In other embodiments, an induction mechanism has a cross-sectional diameter of about 50, 60, 70, 80, 90, 95, or 99%, or ranges between two of these values, of the inner diameter of a reactor body.

[0023] An induction mechanism may be positioned at various locations within a reactor body. For example, in some embodiments, the induction mechanism 332 is positioned at or near the first end 304 in the vicinity of one or more inlet ports 302. In other embodiments, the induction mechanism 332 is positioned so as to leave a space between the induction mechanism 332 and the one or more inlet ports 302.

[0024] Figures 2A and 2B illustrate various embodiments of induction mechanisms suitable for inducing or augmenting vortical flow within a vortex reactor. An induction mechanism may be configured with variable size and number of flights and grooves, variable rotation direction (clockwise or counterclockwise), and variable bore size. The flights may have variable pitch, angle, major diameter, minor diameter, and pitch diameter.

[0025] The embodiment illustrated in Figure 2A is shaped as a helix with flights of continuously decreasing or continuously increasing (depending on orientation) diameter. Such embodiments may beneficially provide desired vortical flows by allowing for an increasingly narrower or increasingly wider gap between the inner surface of a reactor wall and the induction mechanism from the perspective of a reactor fluid as the reactor fluid flows past the induction mechanism.

[0026] Figure 2B illustrates an embodiment of an induction mechanism having varying pitch in order to accelerate the angular velocity of a fluid as it moves forward through the induction mechanism. Such embodiments can enable a gradual increase in angular velocity of a reactor fluid from a beginning level upstream from the induction mechanism to a desired increased level upon exiting the induction mechanism.

[0027] Figures 3A-3C illustrate different views of an embodiment of a reactor 500 including a first inlet port 502 located near a first end 504 (i.e., upstream end), a second inlet port 538 also located near first end 504, a reactor body 508, and an induction mechanism 532 extending toward a second end 506 (i.e., downstream end) from a point at or near first end 504. In the illustrated embodiment, induction mechanism 532 is configured with an exterior induction structure 542 disposed along at least a portion of the exterior side of the induction mechanism and an interior induction structure 544 disposed along at least a portion of the inner surface of the induction mechanism within an interior channel of the induction mechanism (seen in Figures 3B and 3C). A first fluid may be passed into reactor 500 through first inlet port 502, and a second fluid may be passed into reactor 500 through second inlet port 538. The first and second fluids then continue to pass toward second end 506.

[0028] As shown, the first fluid may be passed into reactor body 508, where contact with the exterior induction structure 542 induces or augments a first vortical flow within the first fluid. In addition, the second fluid may be passed into the interior channel of induction mechanism 532, where contact with interior induction structure 544 induces or augments a second vortical flow within the second fluid.

[0029] In some embodiments, the vortical flow of the first fluid and the vortical flow of the second fluid have similar fluid dynamics (e.g., similar angular velocity, linear velocity, pressure, etc.). In other embodiments, the vortical flows of the first and second fluids exhibit different fluid dynamics. For example, exterior induction structure 542 and interior induction structure 544 may be independently configured to provide desired vortical flows for the first fluid and the second fluid, respectively.

[0030] The first and second fluids pass through their respective sections of induction mechanism 532 until arriving at a mixing zone 540 located distally from induction mechanism 532. This mixing zone 540 can beneficially introduce the first and second fluids with high rates of shear mixing and/or emulsification. In some embodiments, the first fluid and the second fluid are induced to rotate in opposite directions to increase mixing in mixing zone 540.

[0031] In some embodiments, the first fluid and the second fluid are different fluids, such as separate fluids that are beneficially mixed together and/or emulsified through operation of reactor 500. In other embodiments, the first fluid and the second fluid are the same, and operation of reactor 500 can augment the degree of mixing within the fluid and/or can further cause other desired physical and/or chemical effects. In some embodiments, the first and/or second fluids are disposed to the mixing zone through an opening sized such that hydrodynamic cavitation is induced. For example, an exit velocity of >20 m/s may be necessary in some fluids to induce hydrodynamic cavitation.

[0032] At high flow rates, cavitation can occur in a turbulent shear flow region due to local pressure reductions in the intense turbulent eddies. The illustrated embodiment enables this form of cavitation within a flow regime that is vortical, providing for bubble growth and collapse that occurs within the fluid medium and not near the surfaces of the apparatus. A radial pressure gradient is created by the vortical movement of the fluid in which the pressure is lower at or near the axis of rotation as compared to locations further out from the axis. Cavitation bubbles will preferentially form in this lower pressure region, then collapse as the influence of the intense turbulent eddies wanes and the fluid flows downstream. The beneficial physical and chemical aspects of cavitation can therefore be exploited within a controlled volume and with minimal cavitation induced erosion damage to the apparatus.

[0033] The illustrated embodiment also includes an energy-imparting device 518 disposed to impart energy into reactor body 508 at or near mixing zone 540. As shown, energy-imparting device 518 may be disposed radially around reactor body 508 near mixing zone 540. Energy -imparting device 518 may be an ultrasound horn or other type of energy-imparting device suitable for particular application needs.

Nanobubble Production

[0034] Figures 4 through 6 illustrate various exemplary embodiments of vortex reactors configured to generate nanobubbles. These embodiments may incorporate one or more of the features of the reactor 500 shown in Figures 3A through 3C. Figure 4 illustrates an embodiment of a reactor 100 including a reactor body 108, an inlet port 102 for conducting a reactor fluid into the reactor body 108, and an induction mechanism 132 with a plurality of flights positioned within the reactor body 108 and configured to contact the delivered reactor fluid to induce vortical motion in the reactor fluid as it passes through the induction mechanism 132.

[0035] The illustrated embodiment also includes a porous element 150 in fluid communication with a gas line 152. The gas line 152 is configured to deliver a gas (e.g., oxygen, nitrogen, ozone, C0₂, argon, air, combinations thereof, or other gas suitable for particular application needs) to an annular space 154 disposed between the inner wall of the reactor body 108 and the porous element 150. Under sufficient pressure, the gas delivered to the annular space 154 is forced through the porous element 150 to form nanobubbles on the inner surface of the porous element 150. The porous element 150 may be a carbon-ceramic material, such as described in U.S. Patent No. 8,919,747, which is incorporated herein by reference in its entirety. Alternatively, the porous element 150 may include one or more of a sintered metal, sintered metal powder, sintered glass beads or particles, porous ceramic, porous polymer, or other suitable sparger material.

[0036] Alternative embodiments may forego the use of pressurized gas and may, for example, omit the gas line 152 and leave the porous element 150 exposed to the ambient atmosphere. Bernoulli's theorem predicts that as a fluid increases in velocity its pressure decreases. When the outer fluid achieves sufficient angular velocity along the outer flow path, the local pressure will drop sufficiently to create a pressure that is negative with respect to the ambient atmosphere. This will allow ambient air to be drawn across the porous element 150 and into the fluid without the need for external compression of the air. At the onset of fluid flow, prior to achieving sufficient angular velocity, there may be some backflow of the fluid through the porous element 150. In many instances, such as where water is used as the outer fluid, this may be acceptable.

[0037] In the illustrated embodiment, the inlet port 102 is aligned with the longitudinal axis of the reactor body 108 and opens at the first end 104 of the reactor. Other embodiments may orient the inlet port 102 to be transverse to the longitudinal axis of the reactor body 108 (such as in Figures 1 and 3A-3C).

[0038] As the fluid moves from the first end 104 toward the second end 106, the variably pitched flights of an upstream section 146 of the induction mechanism 132 progressively accelerate the angular velocity of the fluid. As shown, the pitch of the flights remains substantially constant across the length of a downstream section 148 of the induction mechanism 132. When the reactor fluid reaches the downstream section 148, which substantially coincides with the porous element 150, the downstream section 148 maintains a substantially constant velocity of fluid passing across the pores of the porous structure 150. This feature enables the bubbles formed at the inner surface of the porous element 150 to be subjected to a substantially consistent shearing force, resulting in generated nanobubbles having a narrow size distribution.

[0039] In addition, the arrangement of the downstream section 148 beneficially provides fluid flow with sufficiently high angular velocity to effectively shear the forming nanobubbles from the inner surface of the porous element 150. The downstream section 148 also provides controlled vortical flow with less turbulence at the boundary layer between the fluid and the porous element 150 than a conventional bubble shearing flow. For example, in a conventional process where a fluid jet is directed at a cone-shaped porous structure or the like to shear bubbles from the porous structure would induce much more turbulence at the interface between the fluid and the porous structure. In contrast, the more controlled, directed vortical flow maintains a more consistent shearing force across the porous element 150 of the reactor, which beneficially results in nanobubbles of narrower size distribution.

[0040] In particular, fluid flow is accelerated as the fluid mass enters the higher pitch downstream section 148 of the induction mechanism 132. The pressure gradient at the boundary layer enhances the vorticity concentration very near the wall. The vorticity added to the boundary layer by the accelerated flow has little time to diffuse, such that in the downstream section 148, a larger percentage of the total vorticity is near the inner surface of the porous element 150. This results in a relatively thinner boundary layer and higher wall shear stress.

[0041] Although presently preferred embodiments utilize a downstream section 148 having flights with non-variable pitch, alternative embodiments may vary the pitch of the flights of the downstream section 148. For example, flights having variable pitch may be desired in applications where a broader size distribution is desired and/or to compensate for fluid pressure losses or the buildup of more nanobubbles within the fluid as it passes closer to the second end 106.

[0042] Bubble production rate and/or average bubble size may be controlled by varying operational parameters of the reactor 100. In at least some applications, one or more of bubble production rate or average bubble size may be controlled by adjusting reactor fluid pressure, gas pressure in the gas line 152, the particular construction of the porous element 150 (e.g., materials, length, thickness), and the configuration of the induction mechanism 132 (e.g., arrangement of flights, length, width), for example. [0043] In the illustrated embodiment, the induction mechanism 132 is held in position within the reactor body 108 by a support member 156. The support member 156 may be configured as a support ring, flange spacer, threaded element, or other suitable securing structure for maintaining proper position within the reactor body 108.

[0044] In the illustrated embodiment, the reactor fluid will pick up the generated nanobubbles and carry them toward the second end 106 and out of the outlet 114. Typically, some amount of residual vortical flow will remain with the fluid as it passes to the outlet 114. In some embodiments, one or more flanges, baffles, or other vortex breaking structures may be included downstream from the induction mechanism 132 to revert the fluid flow toward a more laminar profile. One or more ultrasound horns (not shown) may also be provided (e.g., near the second end 106) to impart ultrasound energy to the fluid.

[0045] In the illustrated embodiment, the porous element 150 and annular space 154 are included as part of a selectively detachable cartridge 158. The illustrated cartridge 158 is inserted as part of the reactor body 108 using flanges 160. Alternative embodiments may include threaded fittings or other fastening means. The detachable cartridge 158 may be utilized to customize the relative positioning of the cartridge components (porous element 150, annular space 154, gas line 152) to the other components of the reactor 100, and/or to remove the cartridge components for cleaning or servicing, or to operate the reactor 100 in a non-nanobubble application. Other embodiments may alternatively include one or more of the porous element 150, annular space 154, or gas line 152 as components integrally attached to the remainder of the reactor body 108 (e.g., as in the embodiment of Figure 6).

[0046] Figure 5 illustrates another embodiment of a reactor 200 that is configured similar to the embodiment of Figure 4, but the illustrated reactor 200 further includes a magnetic element 262 disposed around the porous element 250 and that substantially coincides in length with the porous element 250. The magnetic element 262 can beneficially aid in generating smaller nanobubbles and/or in generating nanobubbles having a narrower size distribution as compared to an embodiment without a magnetic element.

[0047] The magnetic element 262 produces a magnetic field which surrounds the porous element 250 and the reactor fluid passing through the porous element 250. When the reactor fluid is electrolytic, the moving fluid will experience the Lorentz force as it passes through the coinciding section of the reactor. [0048] In the illustrated embodiment, the magnetic element 262 includes a plurality of cylindrically-shaped magnets stacked/nested with one another. The magnets are preferably high strength magnets, such as neodymium permanent magnets. The magnets may be magnetized axially or diametrically. In the illustrated embodiment, the magnets are magnetized axially such that the north pole side 264 is disposed toward the first/upstream end 204 and the south pole side 266 is disposed toward the second/downstream end 206. This configuration beneficially positions the magnetic force lines parallel with the longitudinal axis of the reactor 200 and the inner surface of the porous element 250.

[0049] As the electrolytic fluid passes through the downstream section 248 of the induction mechanism 232, the fluid crosses the magnetic field at angles of almost 90 degrees as it moves in a vortical pattern further down the reactor (the angle being determined by the pitch of the corresponding flights of the induction mechanism 232). Charged particles carried within the fluid will be subjected to a force that is perpendicular to the particle direction of motion and the magnetic field lines. In the configuration of the illustrated embodiment (where the fluid is rotating in a clockwise direction when viewed from the first end 204), this results in a force directed radially inward toward the reactor axis. This force beneficially aids in displacing and shearing the forming nanobubbles from the porous element 250, enabling smaller sized nanobubbles to enter the moving reactor fluid.

[0050] Alternative embodiments may be configured with alternative flow patterns (e.g., counterclockwise as viewed from first end 204) and/or different magnet arrangements (e.g., with respect to where the north and south poles are oriented). Whatever the configuration, it is preferred that the resulting Lorentz force is directed radially inward to aid in pushing forming nanobubbles away from the inner surface of the porous element 250.

[0051] The embodiment illustrated in Figures 4 and 5 may be utilized in applications where a single reactor fluid is used. Figure 6 illustrates another embodiment of a reactor 400 configured for mixing of two separate fluid streams and for effectively providing nanobubbles to the fluid mixture. The reactor embodiment of Figure 6 is similar to the embodiment shown in Figures 3A-3C. The illustrated reactor 400 also includes a porous element 450 circumferentially surrounding a downstream section 448 of the induction mechanism 432, an annular space 454, and a gas line 452. The porous element 450, gas line 452, and annular space 454 are configured as the like components of the embodiments of Figures 4 and 5. [0052] During operation, a first fluid is directed into the reactor body 408 through the inlet port 402, where it is passed from the first end toward the second end 406. The first fluid picks up the generated nanobubbles as it passes through the downstream section 448 moves past coinciding porous element 450. A second fluid is passed through the interior of the induction mechanism 432 through inlet 409. As the first fluid passes across the outer surface of the induction mechanism 432 and as the second fluid passes through and out of the interior of the induction mechanism 432, the first and second fluids are combined at the mixing zone 440.

[0053] The illustrated embodiment includes a guide cone 460 configured to direct the mixed fluid streams to a common outlet and/or to adjust the exiting flow (e.g., increase angular velocity if maintaining vortical flow is desired). Other embodiments may omit the guide cone 460. The illustrated embodiment also includes a pair or set of ultrasound horns 418 for imparting ultrasound energy to the nanobubble and fluid mixture. Other embodiments may omit ultrasound horns or may additionally or alternatively include other energy imparting devices (e.g., microwave or low-frequency sound devices) to provide desired chemical and/or physical effects to the nanobubble and fluid mixture. Although not shown here, the embodiment of Figure 6 may also include a magnetic element as with the embodiment of Figure 5.

[0054] The embodiments described herein, including the reactor embodiments of Figures 4 through 6, may include a recirculating/recycle loop for transmitting a portion of the fluid exiting the reactor back to the reactor inlet(s). In one example, a recycle rate of 50% is utilized by recycling about half of the exiting flow back to one or both inlets. Other recycle rates may be utilized according to application needs and preferences. Higher recycling rates may be utilized to provide more thorough mixing and dispersal of nanobubbles or other nano-sized structures within the final mixture.

Downstream Processing of Nanobubbles

[0055] One or more of the reactor embodiments described herein may be operatively coupled to one or more additional downstream processes to further process the generated nanobubbles. In some embodiments, the nanobubble-containing fluid exiting the vortex reactor is directed to a density gradient separator to separate the generated nanobubbles into a plurality of size categories and to further narrow the size distribution of the nanobubbles.

[0056] Figure 7 illustrates an exemplary downstream vortex reactor 801 that may be utilized to separate the nanobubbles according to size. The illustrated embodiment includes one or more inlet ports 802 disposed at a first end 804 of the reactor 801. The illustrated inlet ports 802 are oriented to receive the fluid at an angle that is tangential or substantially tangential to an inner surface of the reactor body 808. The orientation of the inlet ports 802 causes the incoming fluid to form a vortex as it advances into reactor body 808. The generated vortex causes the fluid mixture to be subjected to centripetal and/or centrifugal forces along the trajectory of the vortex.

[0057] The illustrated vortex reactor 801 also includes a second end 806 configured to separate different fractions of the fluid according to different radial zones in which the different fractions accumulate. For example, the vortical motion of the fluid as it moves toward the second end 806 will cause lower density fractions having larger nanobubbles to concentrate closer to the axis of the vortex, while fractions of progressively greater density with smaller nanobubbles will concentrate at positions extending radially outward from the axis. As shown, a series of outlet members 822 are arranged at different radial separation zones, and may be positioned to separately receive different fractions of the fluid passing through the reactor 801.

[0058] The illustrated configuration may be utilized with any of the reactor embodiments described herein to enable effective size separation of the generated nanobubbles and/or effective narrowing of a targeted size distribution. The separate outlet members 822 can be radially positioned to coincide with different separation zones of the fluid. The outlet members 822 may be configured as outlet tubes, channels, conduits, or the like.

[0059] In the illustrated embodiment, the outlet members 822 are positioned at different radial zones and at different elevations within the reactor 801. Positioning the outlet members 822 at different elevations and/or at different tangential angles to the longitudinal axis enables the outlet members 822 to function with minimal disturbance to the vortical flow within the reactor 801. The illustrated embodiment also includes a central outlet 821 where the least dense fraction of the fluid mixture may exit.

[0060] The present disclosure may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the disclosure is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims

CLAIMS What is claimed is:

1. A vortex reactor for generating nano-sized structures, such as bubbles, the vortex reactor comprising:

a reactor body having a first end and a second end;

one or more inlet ports disposed at or near the first end and configured to direct a fluid into the reactor body;

a vortex induction mechanism disposed within the reactor body between the first and second ends, the vortex induction mechanism having a plurality of angled flights for inducing vortical motion within a reactor fluid as the fluid is directed past the induction mechanism; and

a porous element positioned to surround at least a portion of the vortex induction mechanism and positioned so that an inner surface of the porous element contacts the fluid as it moves in a vortical motion past the porous element;

wherein the porous element provides passage of a pressurized gas to the inner surface of the porous element to form nano-sized structures, such as bubbles, the fluid acting to shear the nano-sized structures, such as bubbles, off of the inner surface of the porous element.

2. The reactor of claim 1, further comprising an annular space disposed between an outer surface of the porous element and an inner surface of a coinciding length of the reactor body, the annular space being configured to receive the pressurized gas for passing through the porous element.

3. The reactor of claim 2, wherein one or more gas lines are coupled to the reactor body to deliver the pressurized gas to the annular space.

4. The reactor of any one of claims 1 through 3, wherein the porous element includes a carbon-ceramic material.

5. The reactor of any one of claims 1 through 4, wherein the vortex induction mechanism includes a section having flights configured to progressively increase the angular velocity of the fluid.

6. The reactor of claim 5, wherein the section having flights configured to progressively increase the angular velocity of the fluid is disposed upstream from the porous element.

7. The reactor of any one of claims 1 through 6, wherein the portion of the vortex induction mechanism surrounded by the porous element includes flights that maintain a substantially consistent pitch along the length coinciding with the porous element.

8. The reactor of any one of claims 1 through 7, wherein the vortex induction mechanism includes an inner channel and an interior induction structure disposed along at least a portion of a surface of the inner channel, the inner channel being configured to receive a second fluid.

9. The reactor of claim 8, further comprising a mixing zone disposed downstream from the vortex induction mechanism where the fluid passed into the reactor body through the one or more inlet ports is mixed with the second fluid passed through the inner channel.

10. The reactor of claim 8 or claim 9, wherein the plurality of angled flights and the interior induction structure are configured to induce the fluid and the second fluid to rotate in opposite directions.

11. The reactor of any one of claims 1 through 10, further comprising an energy- imparting device disposed at the second end of the reactor body.

12. The reactor of claim 11, wherein the energy-imparting device is an ultrasound horn.

13. The reactor of any one of claims 1 through 12, wherein the reactor body includes a section configured as a detachable cartridge, the detachable cartridge including the porous element.

14. The reactor of any one of claims 1 through 13, further comprising a guide cone disposed downstream of the vortex induction mechanism.

15. The reactor of any one of claims 1 through 14, further comprising a magnetic element disposed around at least a portion of the porous element, the magnetic element being arranged to direct a magnetic field such that a resulting Lorentz force is directed radially inward toward an axis of the reactor body to aid in detaching the nano-sized structures, such as bubbles, forming on the inner surface of the porous element.

16. A nanobubble generation system, comprising:

a vortex reactor according to any one of claims 1 through 15 configured to generate a nanobubble-containing stream; and

one or more downstream vortex reactors configured to induce vortical motion in the nanobubble-containing stream such that a resulting density gradient separates the nanobubbles according to size.

17. The system of claim 16, wherein one of the one or more downstream vortex reactors includes a series of outlet members disposed at different radial positions to correspond to different separation zones within the downstream vortex reactor.

18. A method of generating nano-sized structures, such as bubbles, the method comprising:

providing a vortex reactor according to any one of claims 1 through 15;

directing a fluid through the vortex reactor to induce vortical motion of the fluid within the vortex reactor; and

directing a gas to the porous element to enable the formation of nano-sized structures, such as bubbles, within the fluid, the vortical motion of the fluid shearing the nano-sized structures, such as bubbles, from the inner surface of the porous element.

19. The method of claim 18, wherein the fluid is electrolytic.

The method of claim 18 or claim 19, wherein the fluid is wastewater and wherein the gas is ozone and/or oxygen.

20. The method of any one of claims 18 through 20, wherein the method is performed in crude oil desalting, wastewater treatment, potable water treatment, or surface water treatment application.