Chemical apparatus and process disinfecting – deodorizing – preser – Process disinfecting – preserving – deodorizing – or sterilizing – Using sonic or ultrasonic energy
Reexamination Certificate
2000-12-19
2004-05-11
Thornton, Krisanne M. (Department: 1744)
Chemical apparatus and process disinfecting, deodorizing, preser
Process disinfecting, preserving, deodorizing, or sterilizing
Using sonic or ultrasonic energy
C422S127000, C422S128000
Reexamination Certificate
active
06733727
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a method and apparatus for treating a fluid, such as the sterilization of water, or a material therein using acoustic energy in the form of cavitation, large amplitude acoustic waves, and/or water hammer, generated by the rapid condensation of steam which is injected into the fluid. More particularly, it concerns a method and apparatus for selectively injecting steam into a reflector member disposed in the fluid which is shaped to focus and direct the acoustic energy at a target zone within the chamber where the acoustic waves converge causing secondary cavitation, the chamber also being shaped to focus the acoustic energy.
2. Background Art
A growing number of municipalities both inside and outside the United States are constrained to using drinking water supplies that come from local rivers, lakes, and reservoirs that contain significant amounts of hazardous micro-organismns. In many cases conventional chemical detoxification methods result in undesirable amounts of chlorine and chlorine byproducts in the treated water. Consequently, the municipal drinking water supply is characterized by water that is unpalatable as well as being a potential health problem. In recent years various non-chemical sonication schemes have been devised to replace or limit the use of chemicals in water treatment procedures.
These sonication schemes utilize high-amplitude ultrasonic sound waves to cause cavitation in a liquid. Cavitation occurs when the high-amplitude ultrasonic sound waves create gas-bubble cavities in the liquid. When the cavities collapse they produce intense localized pressures. This cavitation may be induced to destroy liquid-borne organisms, mix fluids or slurries, promote certain chemical reactions, and otherwise treat fluids or materials therein.
The high-amplitude ultrasonic sound waves are typically generated by electrically driven piezoelectric or magnetostrictive transducers. The transducers are usually directed into a static liquid tank or a tank in which the liquid is circulated in order to sterilize objects within the tank, such as surgical instruments, or to sterilize the fluid itself One disadvantage of transducers is that they are typically confined to small scale systems or batch processes.
Some larger scale systems for processing a continuous flow of water have been proposed. For example, U.S. Pat. No. 5,611,993, issued Mar. 18, 1997, to Babaev, discloses a method which uses various tank configurations and inlet and outlet locations to cause temporary pooling of the water while a transducer for transmitting a high frequency sound wave is directed at the pooled water. U.S. Pat. No. 4,086,057, issued Apr. 25, 1978, to Everett, discloses a free jet of water directed against an ultrasonic vibrating surface. One disadvantage with these systems is that they are not practical for large scale disinfection of a continuously flowing fluid. U.S. Pat. No. 5,611,993, issued Mar. 18, 1997, to Babaev, discloses a plurality of opposing transducers. One disadvantage with some of these systems is their use of a larger number of transducers which consequently utilize a larger amount of electricity to operate.
Other systems require additional processing steps to supplement the sonic process. For example, U.S. Pat. No. 5,466,425, issued Nov. 14, 1995, to Adams discloses a system utilizing an applied voltage, ultraviolet radiation, and high frequency. Similarly, U.S. Pat. No. 5,326,468, issued Jul. 5, 1994, to Cox, discloses cavitation induced by the pressure drop across a nozzle throat and subsequent ultraviolet radiation, ion exchange, and degassifying treatment. See also U.S. Pat. No. 5,494,585, issued Feb. 27, 1996, to Cox; and U.S. Pat. No. 5,393,417, issued Feb. 28, 1995, to Cox. One disadvantage of these systems is their reliance on secondary treatments. Another disadvantage is their continued use of trstems utilize a cavitation chamber. For example, U.S. Pat. No. 5,519,670, issued May 21, 1996, to Walter, discloses a cavitation chamber in which acoustic pulses are generated by repeatedly closing a valve, creating water hammer. The water hammer propagates into the cavitation chamber through a diaphragm. See also U.S. Pat. No. 5,508,975, issued Apr. 16, 1996, to Walter. One problem with this type of system is that repeatedly closing the valve fatigues the system components. Another problem with this type of system is the use of a diaphragm which may become fatigued and fail. Another problem with many systems is the complexity and number of components subject to failure.
Another problem with many of the above systems is that the acoustic energy generated is inefficiently used. For example, the acoustic energy is indirectly propagated from a pipe system into a cavitation chamber. Other systems merely direct the transducer in the desired direction. U.S. Pat. No. 5,459,699, issued Oct. 17, 1995, to Walter, discloses a flexible, indented pipe to direct some of the water hammer in the pipe into a surrounding fluid. Most of the acoustic energy in these systems randomly propagates through the system.
Although most systems utilize transducers to create cavitation, some systems utilize the pressure drop across a nozzle to induce cavitation downstream of the nozzle throat. See U.S. Pat. Nos. 5,326, 468; 5,494,585; and 5,393,417. Traditionally, this type of cavitation sometimes occurs naturally in fluid systems and is generally considered undesirable as it contributes to the fatigue and failure of system components.
In addition to micro-organisms, some fluids or fluid systems also have difficulty with larger organisms. For example, the intake canals of power plants are clogged by zebra mussels. These intake canals typically contain large volumes of water, and conventional chemical treatments can prove to be expensive or environmentally unfriendly.
Furthermore, cavitation is also known to be useful in other processes in addition to sterilization of fluids. Cavitation may also be used to sterilize other materials or objects in the fluid; promote chemical reactions (sono-chemistry); treat wood fibers for paper pulp production; de-gas liquids; mix chemicals or slurries; or break down certain compounds.
Therefore, it would be advantageous to develop a method and apparatus capable of sterilizing a large amount of continuously flowing water suitable for use with municipal water supplies, industrial waste water, or utility water supplies. It would also be advantageous to develop such a method and apparatus which utilizes a novel acoustic source rather than traditional transducers. It would also be advantageous to develop such a method and apparatus that is simple and has fewer components. It would also be advantageous to develop such a method and apparatus which efficiently utilizes the acoustic energy. It would also be advantageous to develop a method and apparatus capable of handling larger organisms.
OBJECTS AND SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a method and apparatus for sterilizing a large amount of continuously flowing water suitable for use with municipal water supplies, municipal waste water, and industrial food processing waste water.
It is another object of the present invention to provide such a method and apparatus for treating other fluids and/or materials and objects in the fluid; promoting chemical reactions; treating wood fibers for paper pulp production; de-gassing liquids; mixing chemicals or slurries; and breaking down certain compounds.
It is another object of the present invention to provide such a method and apparatus which utilizes a less expensive acoustic source, rather than traditional transducers.
It is another object of the present invention to provide such a method and apparatus which is simple; has few moving parts; and has fewer components and is easily serviceable.
It is another object of the present invention to provide such a method and apparatus which efficiently utilizes the acoustic energy.
It is another object o
Bechtel BWXT Idaho LLC
Thornton Krisanne M.
Trask Britt PC
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