Patent Application
20120156309
The present invention relates to solutions of dissolved gas in liquids, and also to mixtures consisting of a solution of gas, e.g., O2, and a dispersion of the gas in a liquid, e.g., water. More specifically, this invention relates to an improved animal wellness system and method that uses an oxygen environment chemically comparable or superior to an oxygen chamber (tent) but without the potentially hazardous accumulation of a pure or oxygen enriched atmosphere.
This invention relates to solutions having quantities of dissolved gas, and more particularly to mixtures containing a solution having quantities of gas and a dispersion of ultra-small microbubbles of the gas in suspension within the solution. These microbubbles generally have a diameter of less than about 125 microns, and preferably less than 50 microns, and are defined as such. It is desirable in the context of this invention to minimize the terminal velocity of the microbubbles within the suspending liquid. Since the residence time of a bubble in a liquid is inversely proportional to the square of the bubble diameter, such microbubbles will have an extended contact time with a fluid as compared to a system consisting of larger diameter bubbles. This quality is known as gas holdup. Additionally, the microbubble/liquid interfacial area is inversely proportional to the square of the bubble diameter. Therefore, it will be shown that a solution of a solute gas such as oxygen in a solvent liquid such as water can be manipulated to produce a dispersion of microbubbles consisting of solute gas nucleated and precipitated from the liquid. This results in extended residence time and a high interfacial area that maximizes the contact between the gas (as microbubbles) and a surface placed within the liquid, such as living tissue.
Various means of exposing living human tissue, in particular skin, to oxygen have been used. These include hyperbaric chambers where a pure oxygen atmosphere is pressurized to, typically, under 3 atmospheres of pressure, and oxygen tents that operate at atmospheric pressure. The use of oxygen tents has known benefits. Cutaneous oxygen uptake through the skin surface can be locally and systemically beneficial by augmenting respiration as an oxygen uptake mechanism. Since cutaneous uptake does not depend on blood circulation through capillaries, local oxygen uptake through the extremities can be beneficial in providing tissue health. Further, a generally enhanced disposition and accelerated recovery from physical exertion can result, as reported by users of oxygen tents. This invention will create similar or enhanced conditions to accomplish these benefits without the accumulation of oxygen in a tent environment. It is contemplated that oxygenated solutions and suspensions of oxygen microbubbles thereof can be used in a variety of applications where an enhanced dissolved oxygen content is desired.
In the human and animal medical community, it is generally known that the effect of oxygen on living tissue can be characterized by three regimes, namely, metabolic enhancement (growth accelerator), metabolic inhibition (growth arrest), and toxicity. In the former regime, oxygenated solutions and microbubble suspensions can be used to accelerate the healing and regeneration rate of damaged tissue. When wounds begin to heal in humans, for example, fibroblastic cells divide and spread throughout the wound area. The fibroblastic cells produce collagen, an important protein that facilitates healing. Supplying sufficient quantities of oxygen to the wound area significantly enhances fibroblast proliferation. In particular, the fibroblastic cells use amino acids hydroxylated with oxygen to synthesize collagen chains.
In addition to treating wounds, oxygen can be used in topical applications for cleaning and revitalizing skin. Various surface contaminants and even parasites can be mediated through exposure to elevated levels of molecular oxygen. In a manner much less aggressive than using a free radical form of oxygen, such as hydrogen peroxide, for example, organic oils on animal skin can be oxidized, solubilized, and transported away by the water component of this form of treatment. Mites and other skin parasites afflicting animals may be exposed to toxic oxygen levels inherent with the oxygen microbubble/water dispersion and residual dissolved oxygen.
Recovery time from physical exertion by, for example, a racehorse can be reduced through the ability to impart oxygen directly to muscular tissue in the extremities. The so called “taught” form of hemoglobin that resides within inter-muscular tissue can be oxygenated by direct cutaneous oxygen transport rather than through hematological means. In situations where the animal is exerted above the lactate threshold, cutaneous oxygenation may facilitate a more rapid recovery from anaerobic metabolism. Bruising and other contusions incurred through exertion may respond to this oxygenated environment as well.
In addition, oxygen can revitalize skin cells by joining with protein molecules to nourish the cells and produce collagen. It is even possible that dissolved oxygen and microbubble suspensions can stimulate hair follicles and consequentially hair growth.
The amount of oxygen initially dissolved into solution is largely dependent on the method used to dissolve the oxygen gas into solution. Generally, these methods consist of two steps: creating a solute gas/solvent liquid interfacial area, and, exposing the gas/liquid mixture to elevated pressure. The former step affects the kinetics or rate at which the solution process occurs while the latter determines the maximum theoretical dissolved. Small bubbles create interfacial area and promote more favorable kinetics. The second step is a pressure-concentration relationship, such as Henry's Law for dilute solutions and Sievert's Law for diatomic gases at higher concentrations. These steps may be combined, although the source of oxygen must operate at a higher final pressure rather than allowing a pump, for example, to pressurize both the liquid and gas components after the gas has been introduced.
One common method for oxygenating water is the coarse bubble aeration process, which is a subset of aeration methods known categorically as air diffusion. Pressurized air or oxygen gas is introduced through a submerged pipe having small holes or orifices into a container of water. Gas pressure is sufficient to overcome the hydrostatic head pressure, and also sustains pressure losses during passage through the small gas orifices. As a result, bubble aeration occurs at relatively low pressures; this pressure being predominantly a function of tube immersion depth and density of the liquid, which in this case is water.
Since all interphase interfaces have a characteristic surface energy, the creation of interfacial (surface) area is an energetic process. As a gas passes through an orifice, for example, pressure energy is converted to kinetic energy, which consequently satisfies the energetic requirements of the system for the production of surface area. Area and velocity are inversely proportional; hence, as the orifice diameter decreases, the corresponding pressure drop and gas velocity increase, and more surface area is generated. Smaller bubbles result. This process has a limiting condition, however, in that the amount of heat (as irreversible work) that is produced is inversely proportional to the square of orifice diameter. It therefore becomes impractical and energetically inefficient to operate at exceptionally small orifice diameters. This process also has an absolute limit as a gas velocity of Mach 1 is approached within the pore of a porous medium used to create bubbles. Because a pore lacks the convergent/divergent geometry required to achieve supersonic flow, increasing pressure beyond the critical pressure will not result in a further reduction of bubble size.
Since oxygen therefore is introduced into solution at relatively low pressures in the coarse bubble aeration process, the oxygen bubbles are relatively large. As a result, the aggregate bubble surface area for a dispersion of bubbles produced by bubble aeration is relatively small. The limited surface area produced by bubble aeration limits the rate at which gas can be dissolved and practically limits the concentration of gas that can be dissolved into solution. Oxygen dissolution is a function of the interfacial contact area between gas bubbles and the surrounding medium, and bulk fluid transport (mixing) in the liquid phase. In particular, the rate of oxygen dissolution is directly proportional to the surface area of the bubbles. A dispersion of very small bubbles, e.g., bubbles having diameters in the order of 50 microns, will have a much larger total surface area than a dispersion of large bubbles occupying the same volume. Consequently, the rate of oxygen dissolution in bubbling aeration is limited by the size of the bubbles introduced into the solvent. Fluid mixing is also very limited in bubbling aeration because the only energy source available for agitation is the isothermal expansion energy of oxygen as it rises in the solution.
Oxygen dissolution in bubbling aeration is also limited by ambient pressure conditions above the solution. If the solution being aerated is exposed to atmospheric conditions, the dissolved oxygen concentration will be limited to the solubility limit of oxygen (at its partial pressure in air of 0.21 atm.) under such conditions. The desirability of bubbling aeration is further hampered by equipment and energy requirements. Large blower units are used to force the gas bubbles into the carrying liquid. These blowers generate high-energy costs and often require special soundproof installations or other engineering costs. Bubble aeration is therefore an impractical process for producing oxygenated solutions or solution/suspensions for health related applications.
Other methodologies have been used to prepare oxygenated solutions based on pressure tanks and adaptations of carbonator devices that dissolve carbon dioxide in water. For a given pressure and temperature, the solubility of carbon dioxide in water exceeds that of oxygen by over an order of magnitude. Carbonators therefore are acceptable for preparing carbonated water solutions but not oxygenated solutions.
In this invention, conditions most favorable to produce a dispersion of small diameter microbubbles in a suspending solvent liquid with high interfacial area are created either at an elevated pressure or with a subsequent increase of pressure. The elevated pressure environment will dissolve the gas in the liquid, since the concentration of a gas in solution and the pressure over the solution is directly related.
High interfacial area enhances the kinetics of the dissolution process, and pressure establishes the maximum concentration of the gas held in solution. For wellness applications, oxygen will be intentionally nucleated from an aqueous oxygen solution to form a dispersion of microbubbles held within the solution and capable of providing the benefits of pure oxygen. Living tissue, in particular, animal skin and/or muscle, that is exposed to such an environment will have the opportunity for oxygen uptake both from the suspension of pure oxygen microbubbles and oxygen adsorbed from the liquid solution at near atmospheric pressure.
It is an object of this invention to provide a novel system for dissolving gas in a liquid. It is another object of this invention to provide a novel system for incorporating large quantities of gas in liquids. It is yet another object of this invention to dissolve large quantities of molecular oxygen in water. It is still another object of this invention to provide large quantities of molecular oxygen in water to provide a saturated solution of metastable molecular oxygen water solution and to create a holdup of microbubbles in suspension within the solution. And still it is yet another object of this invention to use said molecular oxygen water suspension-solutions for health and wellness applications for animal applications similar to oxygen tents. These applications include skin conditions, parasites, exertion recovery, and contusions. Finally, it is another object of this invention to produce saturated and hypersaturated gas-liquid solutions that can be stimulated to nucleate gas bubbles and resulting dispersions for the purposes of providing benefits for animal skin and/or muscle tissue.
These and other objects will become apparent from the claims and drawings appended hereto. In accordance with these objects, there is provided a method of dispersing a gas in a liquid to provide a mixture of a saturated, supersaturated or hypersaturated solution of the gas in the liquid and to optionally provide a suspension of bubbles containing the gas therein. The method comprises the steps of providing a liquid pumping means, a liquid for introducing to the liquid pumping means, and pumping the liquid to a pressure greater than 0.8 atmospheres gage pressure to provide a pressurized liquid. A gas is introduced to the pressurized liquid and dispersed therein to provide a solution having the said gas dissolved therein and having bubbles of the gas. The solution is then subjected to a shearing action to reduce the size of the bubbles to provide a highly hypersaturated liquid and bubbles of said gas having a diameter as low as 5 μm.
Based on the foregoing, an oxygenated mixture is provided having dissolved molecular oxygen content well above the equilibrium limit at ambient conditions. The oxygenated mixture can supply a large amount of molecular oxygen in a medium that is not traumatic to skin tissue. Since the dissolution of oxygen into solution occurs under hyperbaric conditions, a large concentration of oxygen is dissolved into solution. The resulting solution can have a dissolved oxygen content as high as 2000 mg/l. In one embodiment of the solution, an oxygen-enriched solution is accompanied by a dispersion of micro-bubbles held in suspension.
A method for using the oxygenated solution and dispersion for animal health and wellness benefits is provided. The method includes the step of filling a tank or bath with oxygenated solution. The beast body being exposed can be locally, regionally or almost fully immersed in said bath so that areas of the body are submerged into the oxygenated solution and dispersion for contacting skin. As this solution circulates about the tissue layers, the dissolved oxygen nucleates into fine bubbles that attach to skin fragments. Additional energy, as produced by ultrasonic means, can be imparted to facilitate the nucleation of gas bubbles. A volume change occurs upon nucleation of the oxygen bubbles. The dispersion of microbubbles and nucleating bubbles exfoliate tissue layers as the bubbles rise to the surface of the tank/bath.
Alternately, a smaller subregion, rather than the animal's whole flank, etc., may be treated hereby. In that sense, the region of exposure is subjected to a partial tank or other containment immersion. Depending on the size and shape of said region, it may be possible to treat the animal's leg or legs in a common exposure tank.
In other variations, the treatment region may be exposed to a circulating external bandage, cuff or wrap for surrounding the targeted region. Finally, if only topical treatment is needed (or desired) albeit on a more frequent basis and/or for greater lengths of total exposure time(s), the animal may be subjected to oxygenation treatments by washing/rinsing, showering and/or shampooing in an oxygen-rich solution made per the present invention but then stored in suitable gas-retaining bottles for eventual implementation via washing, rubbing and/or massaging into the treatment regions/zones for any given beast.
One preferred application for this treatment is for those animals that “perform athletically”. More particularly, for racing horses and dogs, this invention achieves improved performance without running afoul of drug-based doping concerns. Furthermore, for any such animal subject to performances (including racing), this invention should achieve better and faster recoveries from injuries to skin and/or muscles.
It should be noted that O2 is a molecule (O:O) with shared electrons and that O− is an ion (free radical) with an unpaired electron. Water is formed from free radicals: H++(OH)−=H2O. Free radicals are usually reactive oxygen free radicals which can form from, for example, hydrogen peroxide: H2O2→H2O− or ozone: O3=O2+O−.
This method can also be practiced with any solute/dispersion gas and liquid solvent that is provides benefit to living tissue and/or the host. It may be beneficial, for example to use carbon dioxide as a gas phase to help exfoliate necrotic skin. Carbon dioxide is desirable in this case because of a substantially higher solubility in water as compared to oxygen. During the nucleation of the gas phase to form microbubbles, a significantly greater volume of carbon dioxide gas would be available to form microbubbles as compared to oxygen since dissolved gas is the source of the dispersed gas.microbubbles.
In this instance, the clear solution containing carbon dioxide and water will be first allowed to infiltrate the necrotic skin. Once infiltrated, the solution would be energized using thermal or mechanical energy to cause gas to nucleate and precipitate from solution. In the case of carbon dioxide, a volume change greater than 25:1 will occur. Such an expansion is an energy source for exfoliating necrotic skin that has been infiltrated by the original solution.
Referring specifically to
Referring again to
The supersaturated or hypersaturated molecular oxygen content in solution 15 is preserved by limiting agitation and preventing flow conditions in the solution that can facilitate ebullition of oxygen gases. The high dissolved oxygen content is also maintained by storing the solution 15 in a manner that limits or prevents desorption of the gas. For instance, the solution may be stored and distributed in sealed screw top containers constructed of glass or alternative materials impervious to oxygen diffusion at these high oxygen concentrations.
If oxygenated water is stored in capped bottles, made of an oxygen impervious material, elevated oxygen concentrations can be preserved for extended periods. In an experiment, seven glass bottles were filled with oxygenated water, processed as previously described, and immediately capped. A polargraphic probe was used to measure dissolved oxygen. The initial oxygen concentration was 64.2 mg/l, at a temperature of 17.6° C. Each bottle was uncapped for measurement of oxygen concentration at the intervals below:
It can be seen that over 86 percent of the original dissolved oxygen concentration was retained after 4 days. Such retention of oxygen in solution provides benefits in a number of applications.
As stated earlier, gas microbubbles that nucleate from solution, where the solution is a Newtonian fluid, such as water, rise to the surface and are released into the air above the solution. Gas bubbles rise in such fluids because a net body force exists that projects the bubbles upward. Since Newtonian fluids yield to these forces, the bubbles rise. The mechanics that control bubble rise are explained by Stokes Law, which will be examined later. In some applications, it is desirable to limit or substantially prevent bubbles from rising to the surface of the solution during storage and to maintain the micro-bubble dispersion indefinitely. In particular, it may be commercially desirable to market a product that contains visible oxygen bubbles held indefinitely in a suspension.
A supersaturated or hypersaturated solution of molecular oxygen in water is unstable at ambient pressure by definition. If, for example, the ambient temperature and pressure conditions establish an equilibrium oxygen concentration of 8 mg/l, and an oxygenated solution containing 40 mg/l is prepared at 5 atmospheres pressure, such a solution will have an oxygen concentration of 32 mg/l above the solubility limit. The oxygen-water system will attempt to reject oxygen by nucleating oxygen bubbles. Nucleation can be either a homogeneous or heterogeneous process depending on changes in temperature, mechanical agitation, or the presence of suitable particles that can stimulate gas nucleation. Rapid pressure changes can provoke gas bubble nucleation, and in this invention, a reduction of pressure to ambient typically results in the formation of microbubbles.
The microbubble dispersion 20 is characterized as having a very large surface area through which interfacial transport of oxygen occurs. Interfacial transport of molecular oxygen through a large surface area aids in resupplying oxygen to solution when dissolved oxygen is taken up during chemical reactions. As a result, a large surface area in the microbubble dispersion is desirable.
The mixture 10 preferably contains microbubbles having an average bubble diameter of about 2-9 μm or 10-100 microns. Microbubbles in this size range provide a significantly larger surface area than a cluster of large bubbles containing the same volume of gas. The magnitude of this difference can be visualized by performing calculations for several bubble diameters at a constant volume of gas. The following calculations show the surface areas present for a single bubble, a plurality of one-inch diameter bubbles and a plurality of 50-micron or 5 μm diameter microbubbles, wherein each calculation is based on one cubic foot of gas. The value, r, is the radius of a single bubble, Vo is the volume of a single bubble, Ao is the surface area of a single bubble, and A is the aggregate surface area for the bubble formation:
a. Single bubble:
V
o=4/3πr3; r=(3Vo/4π)1/3
Thus, when Vo=1.00 ft3, r=0.62 ft. Therefore, the diameter of a single bubble containing 1.00 ft3 of gas=1.24 ft.
The surface area of this single bubble (Ab) is:
Ab=4πr2=4π(0.62 ft)2=4.83 ft2
b: For one inch bubbles:
r=0.50 inches=0.042 ft.
V
b=4/3πr3=4/3π(0.042 ft)3=3.1×10−4 ft3/bubble
A
b=4πr2=4(0.042 ft)2=2.22×10−2 ft2
The number of one inch bubbles (nb) in a 1.00 ft3 volume of gas is:
n
b
=V
o
/V
b=1.00 ft3/3.1×10−4 ft3/bubble=3,224 bubbles
The surface area (Ao) of a 1.00 ft3 volume of gas comprised of one inch bubbles therefore is:
A
o
=ΣA
b
=n
b
A
b=3,224 (2.22×10−2 ft)=71.43 ft2
c. For 50μ microbubbles:
r=25μ/3.05×105 μ/ft=8.2×10−5 ft
V
b=4/3πr3=4/3π(8.2×10−5 ft)3=2.31×10−12 ft3
A
b=4πr2=4π(8.2×10−5 ft)2=8.45×10−8 ft2
n
b
=V
o
/V
b=1.00 ft3/2.31×1012 ft3=4.32×1011 bubbles
A
o
=n
b
A
b=4.32×1011(8.45×10−8 ft2)=36,504 ft2
d. For 5 μm microbubbles:
r=2.5μ/3.05×105 μ/ft=8.2×10−6 ft
V
b=4/3πr3=4/3(8.2×10−6 ft)3=2.31×10−15 ft3
A
b=4πr2=4(8.2×10−6 ft)2=8.45×10−10 ft2
n
b
=V
o
/V
b=1.00 ft3/2.31×10−15 ft3=4.32×1014 bubbles
A
o
=n
b
A
b=4.32×1014(8.45×10−10 ft2)=365,800 ft2
These calculations are summarized in accompanying
The driving force for microbubble formation is shown in accompanying
Based on the foregoing calculations, the aggregate surface area for a dispersion of gas bubbles increases by a factor of 10 as the radius of the bubbles decreases by a factor of 10. Referring to calculations (b) and (c), and within rounding error, a dispersion of 50-micron diameter bubbles containing one cubic foot of gas will have an aggregate surface area more than 500 times greater than a dispersion of one-inch bubbles containing the same volume of gas; and a dispersion of 5 μm diameter bubbles containing one cubic foot of gas will have an aggregate surface area 10 times greater than the 50-micron diameter bubbles and 5,120 times greater than a dispersion of one-inch bubbles containing the same volume of gas.
The microbubble suspension 20 is somewhat unstable, as the microbubbles will rise to the surface of the mixture and pass into the atmosphere over time. This movement is generally driven by buoyancy (body) forces. The mechanics of microbubble separation in a liquid can be analytically described for by Stokes' Law for small bubble sizes. Particularly:
V=2gr2(ρg−ρw)/9η,
where V is the terminal velocity of a bubble rising through the liquid, g is the acceleration of gravity, r is the radius of the bubble, ρg is the density of the gas, ρw is the density of the liquid, and η is the Newtonian viscosity of the liquid.
Based on the formula, the terminal velocity of a rising bubble is proportional to the square of the radius of the bubble. In other words, the net upward force that causes a bubble to rise (i.e., the buoyancy force less all drag forces on the bubble) increases dramatically as the size of that bubble increases.
This effect is graphically illustrated in
Referring now to
In
The elevated pressure substantially limits any remaining gas bubbles from increasing in size. The amount of pressure in discharge line 75 varies depending on the size of the system and desired discharge conditions. Preferably, the pressure of the mixture as it enters the discharge line 75 is between about 35 and 450 psig. In the case of oxygen, the amount of this gas that is dissolved in water increases with increasing pressure, as per
As liquid 10 discharges into bath 100, the tank is allowed to fill with minimal agitation or stirring so as to substantially minimize the amount of nucleation and ebullition of gas bubbles. In one preferred embodiment, liquid 10 is expanded through a nozzle or orifice while entering bath 100. The resultant abrupt pressure decrease causes an instantaneous change in gas solubility. That, in turn, causes some precipitation of the dissolved gas to form bubbles of substantially pure gas. If this expansion occurs with sufficient shear, the resulting bubble population will be microbubbles.
Additionally, a secondary stream of liquid at a temperature greater than liquid 10 is mixed with same. As a result, the temperature of the combined liquids increases. That temperature rise also decreases the solubility of gas in liquid 10 and produces bubbles of substantially pure gas.
It has been found that if the two liquids are mixed in a coaxial manner, the resulting bubble population consists substantially of microbubbles and appears almost smoke-like within bath 100. In this way, the maximum quality of gas originally dissolved in liquid 10 is converted to a dispersion of microbubbles within bath 100. In the case of oxygen in water, the bath 100 is preferably filled so that the dissolved oxygen concentration is maintained somewhat above 20 mg/l at 1 atm and 65° F.
Once bath 100 is filled, the solution is allowed to interact with animal tissue. Some of the dissolved oxygen contacts the tissue where it is believed to assist with the regeneration of new tissue cells and also be transported through the skin and enter the bloodstream through capillaries. Additionally, microbubbles of oxygen contact the skin and are expected to provide at least an equivalent benefit to the skin being exposed to pure oxygen in an oxygen tent. The very small diameter of the microbubbles results in an extended retention time within bath 100.
Although elevated dissolved oxygen content in the bath 100 is not stable under atmospheric conditions, in the absence of bubble nucleation, the rate of oxygen liberation at the liquid/atmosphere interface is slow enough that the dissolved oxygen content therein can remain elevated for several hours. After some time, the dissolved oxygen content will decrease down to equilibrium conditions. Preferably, ambient pressure at the location of the bath is maintained between 0.9 atm and 1.1 atm.
Additional energy may be added to the bath solution to stimulate the nucleation of microbubbles and accelerate the exfoliation process. Mechanical mixing or circulation of the bath solution using stirring bars, circulation pumps or other mechanical devices may also stimulate nucleation of microbubbles. In addition to the foregoing, still other stimulation enhancements may include adding one or more localized ultrasonic transducers to the system.
Ordinarily, liquid 10 in continuously introduced into bath 100 resulting in outflow of liquid into a drain. Such one-pass systems are desirable for maximizing sanitation in situations with multiple users. A pipe placed within bath 100 establishes the desired bath depth. It would also allow discharge liquid to flow into a drain for disposal.
As an alternative to a one-pass system, liquid 10 can be recirculated. In
The generation of smaller bubbles in the liquid stream for dissolution requires a significant amount of energy. One method of accomplishing this is to introduce gas into the liquid at a very high speed. In the present method, the gas is preferably introduced at supersonic conditions at the exit of the nozzle 50. The nozzle 50 may be any type of nozzle that permits supersonic gas flow conditions, such as the nozzle disclosed in U.S. Pat. No. 5,463,176. The velocity of the gas at the exit of the nozzle 50 is preferably in the range of Mach 1 to Mach 5 and more preferably in the range of Mach 2 to Mach 4. It will be understood that lesser velocities, such as those below Mach 1, can be used but ordinarily will not provide as much mixing of gas into solution.
The introduction of gas at supersonic conditions into the low-pressure stream creates a two-phase gas/liquid oxygenated mixture 10. The mixture 10 is conveyed through an axial flow turbine based pump known as a co-compressor 70, which concurrently increases the pressure of both gas and liquid in the stream and discharges the mixture into a high-pressure discharge line 75. The pressures of the gas and liquid are increased to allow large quantities of oxygen to efficiently dissolve into the liquid in a short period of time.
Multiple stage axial flow pumps have been found to be suitable for increasing pressure. Diaphragm or piston pumps may be even more suitable because rotational flow is not present that can result in density separation of the gas and liquid, however the flow capacities of such pumps are categorically lower than axial pumps.
As noted, common methods for oxygenating water include using gas diffusers at atmospheric and elevated pressures, packed beds and pressure tanks. Pressurized oxygen gas may be introduced through a submerged pipe having small holes or orifices into a vessel of water. Gas pressure is sufficient to overcome the hydrostatic head pressure while sustaining pressure losses during passage through the small gas orifices. As a result, bubble aeration occurs at relatively low pressures; this pressure being predominantly a function of tube immersion depth. The decrease in gas pressure across an orifice results in an increase in gas kinetic energy. This kinetic energy satisfies the energetic requirement to create surface area, albeit at a low level in this case. Since all interphase interfaces have a characteristic surface energy, the creation of interfacial (surface) area is an energetic process.
Area and velocity are inversely proportional. Hence, as the orifice diameter decreases, the corresponding pressure drop and gas velocity increase, and more surface area is generated. Smaller bubbles result.
This method has a limiting condition in that the amount of heat (as irreversible work) produced is inversely proportional to the square of orifice diameter. It therefore becomes impractical and energetically inefficient to operate at exceptionally small orifice diameters. This process also has an absolute limit as a gas velocity of Mach 1 is approached within the pore. Because a pore lacks the convergent/divergent geometry required to achieve supersonic flow, increasing pressure beyond the critical pressure will not result in a further reduction of bubble size. As noted earlier, a dispersion of very small bubbles, e.g., bubbles having diameters of about 50 microns, will have a much larger total surface area than a dispersion of large bubbles occupying the same volume.
One process uses a Mach 3 supersonic nozzle to dissipate energy at significantly higher levels than conventional orifice-based oxygenation technologies. Oxygen issues from the nozzle countercurrent to water flow, resulting in the explosion of the jet plume into a quasi-emulsion.
A first schematic method alternative is shown in
The water discharged from pre-charge pump 232 is conveyed to the oxygenation system 230 through an influent line 240 maintained at low pressure. Oxygen-containing gas is introduced into influent line 240 through a porous diffusion device 220 connected to a supply of oxygen gas. The diffusion device 220 may have various geometries and be placed in a variety of ways to contact with the liquid.
In
As noted earlier, introducing molecular oxygen to water through a porous diffuser results in relatively large bubbles with low surface area. Increasing gas pressure to provide an increased flow through the pores results in smaller bubbles. If a nozzle having convergent/divergent geometry is used, an increased gas velocity is achieved due to the conversion of pressure energy to surface energy with even smaller bubbles resulting in increased bubble surface area and greater dissolution. Greater surface area of bubbles results in higher levels of dissolved oxygen in water. (Note that: a convergent/divergent nozzle is capable of supersonic gas flow.)
It has been found that limitations exist on the amount of gas/liquid surface area that can be generated by gas expansion through porous materials or nozzles. In one preferred embodiment of this invention, an improved phase contactor was created consisting of a rotating gear like device known as an impeller used to create turbulence and eddys within the incoming water stream. Gas (in this case, oxygen) is introduced to a region in the vicinity of the rotating impeller. That gas stream instantly interacts with the turbulent eddys created by the rotating impeller with the resulting shear believed to reduce the gas stream into very small bubbles. The energy necessary to create gas/liquid interfacial area is supplied by the rotating impeller and not a diffuser or nozzle as previously described.
The rotating impeller will: a) create shear within the body of liquid to form gas bubbles; b) disperse gas bubbles throughout the liquid; and c) agitate the liquid. Efficient bubble formation is dependent on maximizing shear forces in the fluid phase. Energy (i.e., ergs/cm3) is required to generate gas/liquid interfacial area. This energy may be supplied by the reaction of non-rotating liquid with the impeller (shear). Shear is maximized when the radial velocity gradient in the liquid is as great as possible. Alternatively, maximum shear is produced when the radial velocity differential between the liquid phase and rotating impeller is maximized.
Newton's Law of viscosity describes the foregoing situation, viz:
τ=−η(dvφ/dr),
where: τ=shear force, η=Newtonian viscosity (laminar) and dvφ/dr=radial velocity gradient. The radial velocity gradient, dvφ/dr, must be maximized to produce the highest values of τ.
In the case of the rotating impeller, power input increases as the cube of impeller speed.
In
Diffuser 444 is comprised of a porous material to provide pores in a size range of 0.1 to 50 microns (broad size range, narrow size range). Gas is introduced through valve 454 and flows circumferentially through diffuser 444 and then radially inwardly to form gas bubbles in the liquid, particularly in grooves 454. As the rotator spins, it provides a shearing action with the result that bubbles forming are divided into much smaller bubbles, thereby increasing the surface area of the bubbles and greatly increasing dissolution of the gas in liquid.
Diffuser ring 444 may be formed from any suitable material that permits the flow of gas there through. Suitable materials are materials comprised of porous stainless steel, copper and alloys, nickel alloys, ceramics (Si3N4), porous carbon and titanium.
Rotator 448 may be formed from a metal or a plastic material. Preferably, the rotator is formed from stainless steel or Teflon®, titanium, nickel alloys, or ceramic may be used. During operation, the rotator would typically spin at a speed in the range of 75 to 5500 rpm. Shaft 450 may be driven by an electric motor 460. Shaft 450 is mounted on bearing 462 and sealed by end 464. As shown in
Another schematic method alternative is shown in
The terms and expressions, which have been employed herein, are used as terms of description and not of limitation. There is no intention in use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof. It is recognized that various modifications of the embodiments described herein are possible within the scope and spirit of the invention. While the two-phase oxygenated mixture has been described primarily in terms of its use in skin products and topical treatment, the invention is intended for use in any application where a supply of oxygen, via an oxygen tent, may be desired.
The invention is intended to encompass a wide range of solutes and solvents other than oxygen and water. For instance, injecting nitrogen gas into a solvent can form a two-phase mixture in accord with the present invention. A bath solution may be prepared using one or more gases, including, but not limited to air, carbon dioxide, nitrous oxide or a number of inert gases. Still other treatments may be realized by sequentially treating individuals in multiple gas phases. For instance, an initial treatment with CO2, followed by O2 and then, lastly N2O.
Reference to a range herein is meant to include all the numbers in the range, as if specifically set forth. For example, the range of 5-200 would include numbers 6, 7, 8 . . . 198, 199.
Reference herein to oxygen is meant to include molecular oxygen, but reference to molecular oxygen is meant to include only molecular oxygen or diatomic oxygen, or non-free radical.
Having described the presently preferred embodiments, it is to be understood that the invention may be otherwise embodied within the scope of the appended claims.
This application is a continuation-in-part of U.S. application Ser. No. 13/369,385, filed on Feb. 9, 2012, which is related to U.S. Provisional Application Ser. No. 61/574,526, filed on Aug. 4, 2011, itself being related to U.S. application Ser. No. 12/660,012, filed on Feb. 19, 2010, which is a continuation-in-part of U.S. application Ser. No. 11/857,556, filed on Sep. 19, 2007. All of the aforementioned disclosures are incorporated by reference in their entireties herein.
| Number | Date | Country | |
|---|---|---|---|
| 61574526 | Aug 2011 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 13369385 | Feb 2012 | US |
| Child | 13407604 | US | |
| Parent | 12660012 | Feb 2010 | US |
| Child | 13369385 | US | |
| Parent | 11857556 | Sep 2007 | US |
| Child | 12660012 | US |
