Diffuser/emulsifier for aquaculture applications

[0001] This application is a Continuation Application of Ser. No. 10/213,499 filed on Aug. 6, 2002 Issued Pat. No. 6,702,949, issued on Mar. 9, 2004, entitled “DIFFUSER/EMULSIFIER FOR AQUACULTURE APPLICATIONS,” which is a Continuation-in-Part of pending U.S. Patent application Ser. No. 10/123,004 filed on Apr. 15, 2002 entitled “DIFFUSER/EMULSIFIER,” which is a Continuation of U.S. Patent application Ser. No. 08/957,530 filed on Oct. 24, 1997 entitled “DIFFUSER/EMULSIFIER,” now U.S. Pat. No. 6,386,751 and claims priority to Provisional Application No. 60/310,904 filed on Aug. 8, 2001 entitled “A SPARGER/AERATOR FOR AQUACULTURE,” and also claims priority to Provisional Application No. 60/310,543 filed on Aug. 7, 2001 entitled “APPARATUS FOR ODOR CONTROL OF A LIFT STATION,”.

[0002] Not applicable.

[0003] 1. Technical Field

[0004] This invention relates in general to diffusers and, more particularly, to a method and apparatus for diffusing or emulsifying a gas or liquid into a material.

[0005] 2. Description of the Related Art

[0006] In many applications, it is necessary to diffuse or emulsify one material—gas or liquid—within a second material. Emulsification is a subset of the process of diffusion wherein small globules of one liquid are suspended in a second liquid with which the first will not mix, such as oil into vinegar. One important application of the diffusion process is in wastewater treatment. Many municipalities aerate their wastewater as part of the treatment process in order to stimulate biological degradation of organic matter. The rate of biological digestion of organic matter is very dependent upon the amount of oxygen in the wastewater, since the oxygen is necessary to sustain the life of the microorganisms which consume the organic matter. Additionally, oxygen is able to remove some compounds, such as iron, magnesium and carbon dioxide.

[0007] There are several methods of oxygenating water. First, turbine aeration systems release air near the rotating blades of an impeller which mixes the air or oxygen with the water. Second, water can be sprayed into the air to increase its oxygen content. Third, a system produced by AQUATEX injects air or oxygen into the water and subjects the water/gas to a large scale vortex. Tests on the AQUATEX device have shown an improvement to 200% dissolved oxygen (approximately 20 ppm (parts per million)) under ideal conditions Naturally occurring levels of oxygen in water are approximately 10 ppm maximum, which is considered to be a level of 100% dissolved oxygen. Thus, the AQUATEX device doubles the oxygen content of the water. The increased oxygenation levels last only minutes prior to reverting back to 100% dissolved oxygen levels.

[0008] Greater oxygenation levels, and longer persistence of the increased oxygen levels, could provide significant benefits in treating wastewater. Importantly, the efficiency of the organic digestion would be increased and the amount of time need for biological remediation would decrease, improving on the capacity of wastewater treatment facilities.

[0009] Accordingly, a need has arisen for a diffusing mechanism capable of diffusing high levels of one or more materials into another material.

[0010] The present invention disclosed and claimed herein comprises, in one aspect thereof, a method of treatment of water in an aquatic environment. Water is first pumped from a reservoir to a first mixing station. An inert gas is introduced into the pumped water at the first mixing station to provide inert gas saturated water, which inert gas saturated water will displace undesired gasses in the water in the reservoir. The inert gas saturated water is then pumped to a sparging column such that the inert gas and undesired gasses will be released from the inert gas saturated water to provide depleted water. The depleted water is then pumped to a second mixing station, wherein oxygen is introduced into the depleted water to provide oxygen enriched water. The oxygen enriched water is then returned to reservoir.

[0023] The present invention is best understood in relation to FIGS. 1-8 of the drawings, like numerals being used for like elements of the various drawings.

[0024] FIGS. 1 and 1a illustrate a partially block diagram, partially cross-sectional view first embodiment of a device 10 capable of diffusing or emulsifying one or two gaseous or liquid materials (hereinafter the “infusion materials”) into another gaseous or liquid material (hereinafter the “host material”). The host material may be a normally solid material which is heated or otherwise processed to be in a liquid or gaseous state during the diffusion/emulsification process.

[0025] A rotor 12 comprises a hollow cylinder, generally closed at both ends. Shaft 14 and inlet 16 are coupled to the ends of the rotor 12. A first infusion material can pass through inlet 16 into the interior of rotor 12. Shaft 14 is coupled to a motor 18, which rotates the rotor at a desired speed. The rotor 12 has a plurality of openings 22 formed therethrough, shown in greater detail in FIG. 1a. In the preferred embodiment, the openings 22 each have a narrow orifice 24 and a larger borehole 26. The sidewalls 28 of the boreholes 26 can assume various shapes including straight (as shown in FIG. 4), angled (as shown in FIG. 1) or curved.

[0026] A stator 30 encompasses the rotor 12, leaving a channel 32 between the rotor and the stator through which the host material may flow. The stator 30 also has openings 22 formed about its circumference. A housing 34 surrounds the stator 30 and inlet 36 passes a second infusion material to an area 35 between the stator 30 and the housing 34. The host material passes through inlet 37 into the channel 32. Seals 38 are formed between the shafts 14 and 16 and the housing 34. An outlet 40 passes the host material from the channel 32 to a pump 42, where it exits via pump outlet 44. The pump may also be driven by motor 18 or by an auxiliary source.

[0027] In operation, the diffusion device receives the host material through inlet 37. In the preferred embodiment, pump 42 draws the host material on the pump's suction side in order to allow the host material to pass through the channel at low pressures. The first and second infusion materials are introduced to the host material through openings 22. The infusion materials may be pressurized at their source to prevent the host material from passing through openings 22.

[0028] The embodiment shown in FIG. 1 has separate inlets for 16 and 36 for the diffusion materials. This arrangement allows two different infusion materials to be introduced to the host material. Alternatively, a single infusion material could be introduced into both inlets.

[0029] In tests, the embodiment shown in FIG. 1 has demonstrated high levels of diffusion of the infusion material(s) into the host material. Tests using oxygen as the infusion material and water as the host material have resulted in levels of 400% dissolved oxygen in the water, with the increased oxygen levels lasting for days.

[0030] The reason for the high efficiency and persistence of the diffusion is believed to be the result of micro-cavitation, which is described in connection with FIGS. 2a-c. Whenever a material flows over a smooth surface, a rather laminar flow is established with a thin boundary layer that is stationary or moving very slowly because of the surface tension between the moving fluid and the stationary surface. The openings 22, however, disrupt the laminar flow and can cause compression and decompression of the material. If the pressure during the decompression cycle is low enough, voids (cavitation bubbles) will form in the material. The cavitation bubbles generate a rotary flow pattern 46, like a tornado, because the localized area of low pressure draws the host material and the infusion material, as shown in FIG. 2a. When the cavitation bubbles implode, extremely high pressures result. As two aligned openings pass one another, a succusion (shock wave) occurs, generating significant energy. The energy associated with cavitation and succussion mixes the infusion material and the host material to an extremely high degree, perhaps at the molecular level.

[0031] The tangential velocity of the rotor 12 and the number of openings that pass each other per rotation dictate the frequency at which the device operates. It has been found that operation in the ultrasonic frequency can be beneficial in many applications. It is believed that operating the device in the ultrasonic region of frequencies provides the maximum succussion shock energy to shift the bonding angle of the fluid molecule, which enables it to transport additional infusion materials which it would not normally be able to retain. The frequency at which the diffuser operates appears to affect the degree of diffusion, leading to much longer persistence of the infusion material in the host material.

[0032] In some applications, a particular frequency or frequencies may be desired to break down certain complex molecules, such as in the case of water purification. In this application, multiple frequencies of succussion can be used to break complex structures, such as VOCs (volatile organic compounds), into smaller sub-structures. Ozone can be used as one of the infusion materials to oxidize the sub-structures at a high efficiency.

[0033] Other sonochemistry applications can be performed with the device 10. In general, sonochemistry uses ultrasound to assist chemical reactions. Typically, the ultrasound is generated using a piezoelectric or other electro-acoustical device. A problem associated with electro-acoustical transducers is that the sound waves do not provide uniform sound waves throughout the material; rather, the desired cavitation is localized around the device itself. The present invention allows the ultrasonic waves to be produced throughout a material using a simple mechanical device.

[0034] FIG. 3 illustrates an exploded view of an embodiment of the rotor 12 and stator 30 where multiple frequencies may be obtained at a single rotational velocity. In FIG. 3, three circular arrays of openings 50 (shown individually as arrays 50a, 50b, and 50c) of openings 22 are disposed circumferentially about the rotor 12. Each ring has a different number of openings evenly spaced about its circumference. In similar fashion, the stator 30 would have three circular arrays of openings 52 (shown individually as arrays 52a, 52b, and 52c). To ensure that only one pair of openings between corresponding arrays will be coincident at any one time, the number of openings 22 in a given array 52 on the stator 30 can be one more (or less) than the number of openings 22 in the corresponding array 50 of the rotor 12. Thus, for example, if array 50a had twenty openings evenly spaced around the circumference of rotor 12, array 52 could have 21 openings spaced evenly around the circumference of stator 30.

[0035] As the rotor 12 of FIG. 3 rotates relative to stator 30, each array will create succussions at a different frequency. By properly choosing different frequencies, a sum and difference interference pattern will result, creating a wide spectrum of frequencies. This spectrum of frequencies can be beneficial in many applications where unknown impurities in a host liquid need to be broken down and oxidized.

[0036] FIG. 4 illustrates a cross-sectional side view of an embodiment of a stator 30. For smaller diameter stators, it may be difficult to form the borehole 26 on the inside of stator 30. The embodiment of FIG. 4 uses an inner sleeve 54 and an outer sleeve 56. The boreholes 26 can be drilled, from the outside, of the inner sleeve 54. For each borehole 26 on the inner sleeve 54, a corresponding aligned orifice 24 is drilled on the outer sleeve 56. The inner sleeve 54 is then placed in, and secured to, the outer sleeve 56 to form the stator 30. Other methods, such as casting, could also be used to form the stator 30.

[0037] FIGS. 5a-b and 6 illustrate alternative embodiments of the diffuser 10. Where appropriate, reference numerals from FIG. 1 are repeated in these figures.

[0038] FIG. 5a illustrates an cross-sectional side view of an embodiment where the rotor 12 and stator 30 are disk shaped. FIG. 5b illustrates a top view of the disk shaped rotor 12. The stator 30 is formed above and below the rotor 12. Both the stator 12 and rotor 30 have a plurality of openings of the type described in connection with FIG. 1, which pass by each other as the rotor 12 is driven by the motor. As before, for each array 52, the stator 30 may have one opening more or less than the corresponding array 50 in rotor 12 in order to prevent simultaneous succussion at two openings within an array. The openings 22 can be of the same shape as shown in FIG. 1. A hollow shaft serves as the inlet 16 to the interior of the disk shaped rotor for the first infusion material. Similarly, an area 35 between the stator 30 and the housing 34 receives the second infusion material. As the host material flows in the channel 32 between the rotor 12 and the stator 30, it is subjected to the vortex generation at the openings 22, thereby causing a diffusion of the first and second materials with the host material. The infused host material passes to outlets 40.

[0039] FIG. 5b illustrates a top view of the rotor 12. As can be seen, a plurality of openings forms concentric arrays of openings on the rotor 12. Each array can, if desired, generate secussions at different frequencies. In the preferred embodiment, openings 22 would be formed on the top and bottom of the rotor 12. Corresponding openings would be formed above and below these openings on the stator 30.

[0040] FIG. 6 illustrates a cut away view of an embodiment of the invention where the rotor 12 has a conical shape. Both the stator 12 and rotor 30 have a plurality of openings of the type described in connection with FIG. 1, which pass by each other as the rotor 12 is driven by the motor. In addition to the openings around the circumference of the rotor 12, there could also be openings at the bottom of the conical shape, with corresponding openings in the portion of the stator 30 at the bottom. As before, for each array, the stator 30 may have one opening more or less than the rotor 12 in order to prevent simultaneous succussion at two openings 22 on the same array. A hollow shaft serves as the inlet 16 to the interior of the disk shaped rotor for the first infusion material. Similarly, an area 35 between the stator 30 and the housing 34 receives the second infusion material. As the host material flows between the rotor 12 and the stator 30, it is subjected to the vortex generation at the openings 22, thereby causing a diffusion of the first and second materials with the host material. The infused host material passes to outlets 40.

[0041] In the embodiments of FIGS. 5a-b and 6, because the arrays of openings 22 can be formed at increasing diameters, generation of multiple frequencies may be facilitated. It should be noted that any number of shapes could be used, including hemi-spherical and spherical shapes to realize the rotor 12 and stator 30.

[0042] The diffuser described herein can be used in a number of applications. Optimal opening size (for both the orifice 24 and borehole 26), width of channel 32, rotational speed and rotor/stator diameters may be dependent upon the application of the device.

[0043] As described above, the diffuser 10 may be used for water aeration. In this embodiment air or oxygen is used as both the first and second infusion materials. The air/oxygen is diffused into the wastewater (or other water needing aeration) as described in connection with FIG. 1. It has been found that the diffuser can increase the oxygenation to approximately 400% dissolved oxygen, with greater concentrations expected as parameters are optimized for this application. In tests which circulated approximately twenty five gallons of municipal water at ambient temperatures (initially having a reading of 84.4% dissolved oxygen) through the device for five minutes to achieve 390% dissolved oxygen content, the enhanced concentration of oxygen levels remained above 300% dissolved oxygen for a period of four hours and above 200% dissolved oxygen for over 19 hours. After three days, the dissolved oxygen content remained above 134%. In these tests, frequencies of 169 kHz were used. The sizes of the openings were 0.030 inches for the orifice 24 and 0.25 inches for the borehole (with the boreholes 26 on the rotor having sloped sides). Cooler temperatures could significantly increase the oxygenation levels and the persistence.

[0044] Also for the treatment of wastewater, or for bio-remediation of other toxic materials, oxygen could be used as one of the infusion materials and ozone could be used as the other infusion material. In this case, the ozone would be used to oxidize hazardous structures in the host material, such as VOCs and dangerous microorganism. Further, as described above, a set of frequencies (as determined by the arrays of openings in the rotor 12 and stator 30) could be used to provide an destructive interference pattern which would break down many of the complex structures into smaller substructures. Alternatively, if the treatment was directed towards oxidation of a single known hazardous substance, it would be possible to use a single frequency which was known to successfully break down the structure. Conversely, a set of frequencies which result in a constructive interference pattern could be used to combine two or more compounds into a more complex and highly structured substance.

[0045] For producing potable water, ozone could be used as the first and second infusion material to break down and oxidize contaminants.

[0046] While the operation of the diffuser 10 has been discussed in connection with large applications, such as municipal wastewater remediation, it could also be used in household applications, such as drinking water purifiers, swimming pools and aquariums.

[0047] The diffuser could also be used for other applications where diffusion of a gas or liquid into another liquid changes the characteristics of the host material. Examples of such applications would include the homogenization of milk or the hydrogenation of oils. Other applications could include higher efficiencies in mixing fuel and gases/liquids resulting in higher fuel economy.

[0048] FIGS. 7a-b illustrate alternative embodiments for the rotor 12 and stator 30. In FIG. 7a, the “stator” 30 also rotates; in this case, the frequency of the successions will be dependent upon the relative rotational speed between the rotor 12 and stator 30. In FIG. 7b, one of either the rotor 12 or stator 30 does not pass an infusion material through the component (in FIG. 7b only the rotor passes an infusion material); the component which does not pass an infusion material has its openings 22 replaced by cavities 58 to produce the turbulence. The cavities 58 could be shaped similarly to the boreholes 26 without the accompanying orifices 24.

[0049] In FIG. 7c, the orifice 24 through which the infusion material is passed through the rotor 12 or stator 30 is positioned next to the borehole 26, rather than in the borehole 26 as in previous embodiments. It should be noted that the primary purpose of the borehole 26 is to disrupt the laminar flow of the host material along the surface of the rotor 12 and stator 30. The compression and rarefaction (decompression) of the host material causes the micro-cavitation, which provides the high degree of diffusion produced by the device. During decompression, voids (cavitation bubbles) are produced in the host material. The cavitation bubbles grow and contract (or implode) subject to the stresses induced by the frequencies of the succussions. Implosions of cavitation bubbles produce the energy which contribute to the high degree of diffusion of the infusion materials into the host material as it passes through the channel 32. Thus, so long as the infusion materials and the host material are mixed at the point where the cavitation and resultant shock waves are occurring, the diffusion described above will result.

[0050] FIG. 7d illustrates an embodiment where the initial mixing of the host material and one or more infusion materials is performed outside of channel 32. In this embodiment a Mazzie diffuser 60 (or other device) is used to perform the initial mixing of the infusion material(s) and the host material. The mixture is input into the channel 32 between the rotor 12 and stator 30, wherein undergoes the compression/rarefaction cycles discussed above, which cause cavitation in the mixture, and is subjected to the frequency of the shock waves.

[0051] Further, the generation of the cavitation and shock waves could be performed using structures which differ from the boreholes 26 shown in the embodiments above. As stated above, the boreholes 26 are surface disturbances which impede the laminar flow of the host material along the sidewalls of the channel 32. In FIG. 7e, a protrusion, such as bump 62 could be used as a surface disturbance in place of or in conjunction with the boreholes 26. Shapes other than rounded shapes could also be used. As shown in FIG. 7f, grooves (or ridges) 64 could be formed in the rotor 12 and/or stator 30 to generate the cavitation and shock waves.

[0052] As stated above, not all applications require, or benefit from, the generation of shock waves at a particular frequency. Therefore, the rotor 12 or stator 30 could have the boreholes 26 (or other surface disturbances) arranged such that a white noise was produced, rather than a particular frequency. The structures used to create the cavitation need not be uniform; a sufficiently rough surface be formed on the rotor 12 or stator 30 will cause the cavitation. Additionally, as shown in FIG. 7g, it may not be necessary for both the surface of the rotor 12 and the surface of the stator 30 to create the cavitation; however, in most cases, operation of the device 10 will be more efficient if both surfaces are used.

[0053] FIG. 7h illustrates a embodiment where the movement which causes the cavitation is provided by the host material (optionally with entrained infused material) rather than by relative motion of the rotor 12 and stator 30. In the embodiment of FIG. 7h, the channel 32 is formed between two walls 66 which are static relative to one another, one or both of which have surface disturbances facing the channel 32. The host material is driven through the channel at high speed using a pump or other device for creating a high speed flow. One or more infusion materials are input into the channel, either through orifices 24 or by mixing the host material with the infusion materials external to the channel. The high speed of the host material relative to the walls 66 causes the micro-cavitation and succussions described above.

[0054] As an example, one or more of the walls 66 could be a fine mesh, through which the infusion material(s) flows to mix with the host material in the channel 32. The surface disturbances in the mesh would cause micro-cavitations and succussions as the host material flows over the mesh at high speed. The frequency of the succussions would depend upon the resolution of the mesh and the speed of the host material. Once again, the infusion materials would diffuse into the host material at the molecular level at the micro-cavitation sites.

[0055] FIGS. 8a and 8b illustrate another embodiment, where a rotating member 70 is disposed within a conduit 72 and rotated by motor 73. The host material and infusion material(s) are mixed in the conduit 72 upstream from the rotating member 70 using a Mazzie diffuser 74 or other device. The rotating member could be, for example, propeller or auger shaped. On the surface of the rotating member 70 has one or more surface disturbances 76, such that the rotation of the rotating member 70 creates the microcavitation discussed above, thereby causing a high degree of diffusion between the materials. The shape of the propeller blades and pattern of the surface disturbances 76 thereon could create the cavitation and succussion at a desired frequency for purposes described above. Further, the shape of the rotating device could draw the materials through the conduit.

[0056] The present invention provides significant advantages over the prior art. First, the micro-cavitations generated by the device allow diffusion to occur at a molecular level, increasing the amount of infusion material which will be held by the host material and the persistence of the diffusion. Second, the micro-cavitations and shock waves can be produced by a relatively simple mechanical device. Third, the frequency or frequencies of the shock wave produced by the device can be used in many applications, either to break down complex structures or to aid in combining structures. Fourth, the cavitations and shock waves can be produced uniformly throughout a material for consistent diffusion.

[0057] Referring now to FIG. 9, there is illustrated a diagrammatic view of the use of the diffuser/emulsifier described hereinabove for use in removing carbon dioxide from water in aquatic reservoir 902. When aquatic animals are disposed in a reservoir such as a pond or a tank, certain gasses and impurities can build up in the tank which can result in a higher level of carbon dioxide and a lack of oxygen in the water. In the instantiation illustrated in FIG. 9, a pump 904 is provided for drawing water out of the reservoir 902 through a screened filter 906 on the input thereof and through a pipe 908. The pump pushes the fluid outward through a pipe 910 into a first diffuser/emulsifier 912 that is operable to aerate the fluid with gas through mixing, diffusing or whatever. One example of this is that described hereinabove. The gas that is provided is either nitrogen in the form of N₂, as provided by a source 916 or ozone, O₃, as provided by a source 918. Any other inert gas could be utilized other than N₂. A gating valve 920 is provided for selecting nitrogen or ozone. Nitrogen can be utilized to force carbon dioxide out of the water by combining with the water molecules. The first step in the process is to select the nitrogen source 916 with the gate 920 and to inject nitrogen into the water. This will displace the carbon dioxide molecules that may be in the water. This nitrogenated water will then be passed through an outlet pipe 930 to a column sparger 932 which will inject the fluid that is saturated with Nitrogen and has the carbon Dioxide contained therein in a gaseous form into the bottom of a column and allow it to rise upward as gas bubbles in the water 934 that is within the column 932. This will result in the N₂ and CO₂ being released in the water column through the sparging process, thus providing water with a lower concentration of N₂ and CO₂ being disposed in a lower portion 936 of the column 932. This is then passed through a filtration system 938. This filtration system is provided to filter out certain particulate matters of various size. This could use some type of HEPA filter. This could also utilize some type of ultraviolet light for killing microbial organisms. The filtered effluent is then output through an outlet pipe 940 to a second diffuser/emulsifier 950 which is operable to diffuse, mix or aerate the water with oxygen from a source 952. This will operate as described hereinabove. This will therefore provide oxygen saturated water on a outlet pipe 952 that is input back to the reservoir 902.

[0058] The system of FIG. 9 therefore provides for first removing harmful gasses from the water with the use of nitrogen. After the harmful gasses are removed, then the water will be somewhat oxygen deficient. This will be solved by then saturating the water with oxygen again. As an alternate embodiment, the gate 920 can inject ozone into the water through the diffuser/emulsifier 912 which will operate to sterilize the water. Further, although not illustrated, the ozone could be injected at the diffuser/emulsifier 950.

[0059] Referring now to FIG. 10, there is illustrated an alternate application utilizing the diffuser/emulsifier described hereinabove. In the embodiment of FIG. 10, there is provided a deep well 1002 that has water 1004 disposed in the bottom thereof. A self contained diffuser/emulsifier 1006 is provided that is disposed in the bottom of the well 1002. An oxygen source 1008 is provided at the top of the well, this providing either oxygen or air. This is provided under pressure to a pipe 1010 down to the diffuser/emulsifier 1006 which diffuser/emulsifier 1006 is operable to mix the oxygen or air with the water to saturate the water with the oxygen or air. An electrical source 1020 is provided at the surface that provides power to the diffuser/emulsifier 1006. With the use of the diffuser/emulsifier 1006, air is not only provided to the water for the purpose of increasing the oxygen level thereof, but it is also introduced such that it will saturate the liquid. This is to be compared with the introduction of air into the bottom of a well that is allowed to free flow upwards to mix with the air. Further, the diffuser/emulsifier 1006 will introduce the air at the bottom of the well such that the portion thereof that is saturated with oxygen or air is at the bottom of the well. A pump 1024 is provided for pumping fluid from the bottom of the well outward through a delivery pipe 1026 to a remote location. As such, the oxygenated or aerated water can be concentrated around the pump itself.

[0060] Although the Detailed Description of the invention has been directed to certain exemplary embodiments, various modifications of these embodiments, as well as alternative embodiments, will be suggested to those skilled in the art. The invention encompasses any modifications or alternative embodiments that fall within the scope of the Claims.