Colloid systems and wetting agents; subcombinations thereof; pro – Continuous liquid or supercritical phase: colloid systems;... – Having discontinuous gas or vapor phase – e.g. – foam:
Reexamination Certificate
1996-01-03
2002-02-05
Anthony, Joseph D. (Department: 1714)
Colloid systems and wetting agents; subcombinations thereof; pro
Continuous liquid or supercritical phase: colloid systems;...
Having discontinuous gas or vapor phase, e.g., foam:
C422S045000, C422S120000, C604S023000, C604S024000, C604S286000, C261S107000, C261S116000
Reexamination Certificate
active
06344489
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
This invention relates to a new stabilized form of gas-enriched liquid produced by a process comprising generally the steps of: preparing a mixture of a gas and a liquid; compressing the mixture so that the gas completely dissolves in the liquid to form a gas-enriched liquid either before or after enclosing the mixture in a confined space.
2. Description of Background Art
The maximum concentration of gas achievable in a liquid ordinarily is governed by Henry's Law. At ambient pressure, the relatively low solubility of many gases, such as oxygen or nitrogen, within a liquid such as water produces a low concentration of the gas in the liquid. However, there are many applications wherein it would be advantageous to employ a gas concentration within the liquid which greatly exceeds its solubility at ambient pressure. Compression of a gas/liquid mixture at a high pressure can be used to achieve a high dissolved gas concentration, but disturbance of a gas-supersaturated liquid by attempts to eject it into a 1 bar environment from a high pressure reservoir ordinarily results in cavitation inception at or near the exit port. The rapid evolution of bubbles produced at the exit port vents much of the gas from the liquid, so that a high degree of gas-supersaturation no longer exists in the liquid at ambient pressure outside the high pressure vessel. In addition, the presence of bubbles in the effluent generates turbulence and impedes the flow of the effluent beyond the exit port.
U.S. Pat. No. 4,664,680 relates to enriching the oxygen content of water. That reference discloses a number of conventional types of apparatus that can be used for continuously contacting liquid and oxygen-containing gas streams to effect oxygen absorption. To avoid premature liberation of dissolved oxygen before it is incorporated within the bulk of matter to be enriched in oxygen content, pressurizable confined flow passageways are used.
Other oxygen saturation devices are disclosed in U.S. Pat. Nos. 4,874,509; and 4,973,558. These and other approaches leave unsolved the need to infuse gas enriched fluid solutions from a high pressure reservoir toward a reaction site at a lower pressure without cavitation or bubble formation in the effluent at or near the exit port.
SUMMARY OF THE INVENTION
In a co-pending application Ser. No. 152,589, filed Nov. 15, 1993 now U.S. Pat. No. 5,407,426, a method is described for the stabilization of a stream of oxygen-supersaturated water which permitted ejection of the stream from a high pressure vessel into a 1 bar environment without cavitation inception in the effluent at or near the exit port(s). An effluent of water containing oxygen at a concentration as high as on the order of 4 cc oxygen/g of injectate, representing a partial pressure of approximately 140 bar of the dissolved gas, can be ejected from a high pressure vessel into a 1 bar liquid environment with complete absence of cavitation inception in the ejected stream. In air at 1 bar, cavitation inception in a high velocity stream is delayed until breakup of the ejected stream into droplets.
The absence of cavitation inception in water supersaturated with oxygen at a high concentration permits its in vivo infusion into either venous or arterial blood for the purpose of increasing the oxygen concentration of blood without incurring the formation of bubbles which would otherwise occlude capillaries.
In addition to this application as previously described, a wide variety of other applications would benefit from ejection of a gas-supersaturated fluid from a high pressure reservoir into an ambient pressure environment in a manner which is unassociated with cavitation inception at or near the exit port. For example, organic material and plant waste streams, e.g., paper mills and chemical plants, often require an increase in dissolved oxygen content before the discharge of such waste streams in a body of water. U.S. Pat. No. 5 4,965,022 also recognizes that a similar need may also occur at municipal waste treatment plants and that fish farms require increased dissolved oxygen levels to satisfy the needs of high density aquaculture. Other applications are disclosed in my U.S. Pat. No. 5,261,875.
A method is described for ejection of gas-supersaturated fluids or liquids from a high pressure reservoir to a relatively low pressure environment, including ambient pressure, which permits the use of the gas-supersaturated liquid at the lower pressure without immediate cavitation inception. Cavitation nuclei in the liquid are removed by compression in a high pressure reservoir. The use of suitable channels at the distal end of the system for delivery of the gas-supersaturated liquid, plus elimination of cavitation nuclei along the inner surface of the channels, allow ejection of the liquid into a relatively low pressure environment without cavitation inception at or near the exit port.
Thus, an important aspect of the invention described herein is the use of capillary channels at the distal end of the delivery system, along with initial hydrostatic compression of a liquid to remove cavitation nuclei along the inner surface of the channels. When such nuclei contain a relatively insoluble gas, such as oxygen or nitrogen, a hydrostatic pressure of 0.5 to 1.0 kbar is highly effective for this purpose. For nuclei of a soluble gas, such as carbon dioxide, a lower hydrostatic pressure can be used for their dissolution. Cavitation nuclei and bubbles in the bulk liquid are removed in the high pressure reservoir by either direct hydrostatic compression, for example, from movement of a liquid or piston driven by a hydraulic compressor, or by compression from a source of gas maintained at a pressure which would provide the desired concentration of gas in the liquid. Hydrostatic compression to 0.1 to 1.0 kbar rapidly removes cavitation nuclei and bubbles from the liquid, but much lower pressures from a gas source are also effective, although requiring longer periods of time. When a gas source is used to both pressurize the liquid and achieve a desired concentration of a relatively insoluble gas in the liquid, the range of gas pressure would typically be in the 10 bar to 150 bar range. When a highly soluble gas, such as carbon dioxide is used, a lower gas pressure, in the range of 2 to 8 bar would typically be employed to achieve a dissolved gas concentration of interest, and a higher level of hydrostatic pressure, on the order of 0.1 kbar to 1.0 kbar, is then applied to remove gas nuclei.
As a result of the lack of cavitation inception at or near the exit port, a stream of gas-supersaturated liquid can be used to enrich a gas-deprived liquid with gas outside the high pressure reservoir simply by convection of the gas-supersaturated effluent with the gas-deprived liquid at ambient pressure. Enrichment of a gas-deprived liquid with gas by diffusion from the gas phase to the liquid is, by contrast, an extremely slow process. The lack of bubbles in the effluent additionally permits unimpeded ejection into the gas-deprived liquid. When the gas-supersaturated liquid is ejected in an air environment, the lack of cavitation inception at or near the exit port facilitates the use of the effluent in a manner similar to use of the same liquid which is not supersaturated with gas, i.e., the ejected stream remains intact, rather than becoming disintegrated into a diffuse spray near the exit port from rapid growth of gas nuclei.
Based on the teachings in the above applications and U.S. patents and the disclosure in the present application that more particularly point to certain embodiments of these teachings, the presently claimed invention provides a stabilized gas-enriched liquid produced by a process comprising the steps of:
a) preparing a mixture of gas and liquid;
b) compressing the mixture to a pressure such that the gas completely dissolves in the liquid to form a gas-enriched liquid;
c) enclosing the gas-enriched liquid within a confined space while retaining substantially the same pressure,
wherein
Anthony Joseph D.
Kivinski Margaret A.
Wayne State University
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