Liquid purification or separation – Structural installation – Closed circulating system
Reexamination Certificate
2001-02-12
2004-04-06
Hoey, Betsey Morrison (Department: 1724)
Liquid purification or separation
Structural installation
Closed circulating system
C210S188000, C210S192000, C210S194000, C210S205000, C261S075000, C261SDIG001, C261SDIG004
Reexamination Certificate
active
06716340
ABSTRACT:
FIELD AND BACKGROUND OF THE INVENTION
This invention relates to a water treatment system. More specifically, the invention is for treating water circulating in a device or machine, such as (but not limited to) a cooling tower using ozone, in order to remove from that water bacteria, viruses, yeast, mold, protozoa, algae and/or other biological or chemical components which not only affect the purity and effectiveness of the water in the device, but may also produce corrosion, scaling, oxidation and other effects which damage the hardware, including pipes and machinery containing the water. Removal of these components helps prevent disease, especially Legionella. The invention is also for a cooling tower or other water circulating machine including the water treatment system.
There are various patents in the literature which use cooling tower ozonation systems for inhibiting, reducing or otherwise eliminating biological and other components in aqueous solution systems. For example, U.S. Pat. No. 5,186,841 (Schick) describes a cooling water ozonation system for injecting ozone into a pressurized stream of aqueous solution, allowing the ozone injected stream to flow certain distances at certain velocities so that some of the ozone injected is dissolved. Schick has as an object of the invention the dissolution of increased amount of ozone in an effort to decrease the amount of ozone needed in the system.
U.S. Pat. No. 6,086,772 (Tanimura) describes a method and apparatus for preventing biofouling in cooling water systems by intermittently injecting concentrated ozone into a recirculating line of a cooling water system, in which cooling water is made to circulate in a closed system. U.S. Pat. No. 4,172,786 (Frosch) describes the ozonation of cooling tower water by continuously injecting ozone into water circulating between a cooling tower and heat exchanger so as to inhibit formation of further deposits, promote descaling of existing deposits, and inhibit chemical corrosion.
U.S. Pat. No. 5,106,497 (Finnegan) describes an ozone treatment system utilizing an airlift pump as a mixer and as a circulating means. This patent describes an invention for ozone treatment which eliminates the need for a circulating pump, making substantial energy savings.
Other patents related, but not pertinent, to the present invention of water treatment systems using ozone include: U.S. Pat. No. 4,981,594 (Jones); U.S. Pat. No. 5,879,565 (Kusmierz); U.S. Pat. No. 5,174,901 (Smith); U.S. Pat. No. 3,610,107 (DeLoach); U.S. Pat. No. 4,839,064 (McBurney), and International Applications WO 94/25150 (Rez-Tek) and WO 98/31636 (Enproamerica).
One of the reasons for treating the water in cooling towers (or any other machine circulating water as part of a cooling or purifying mechanism) is that such cooling towers have recently been recognized as a major source of Legionella infection. It is also recognized that ozone is a very effective biocide, small concentrations of which have been shown to have good performance in killing bacteria, yeasts and the like.
Appropriate dosing of ozone in water cooling systems is problematical with many formulae to calculate the amount of ozone needed to treat a given volume of water. Such formulae and calculations often do not take into account the fact that environmental conditions differ from one tower to another, as does the water, temperature and other parameters. Moreover, these parameters may change daily and seasonally at a particular cooling tower. The result has been a trend to use maximum ozone doses possible to ensure that enough ozone will be present to cover all extremes. However, ozone generators are expensive to install and maintain, and since ozone is only marginally soluble in water, excess production outgases into the atmosphere, often creating an offensive ozone smell.
Further, chillers and other hardware will react unfavorably when in contact with ozone. Corrosion is a significant result of high concentrations of ozone within a system. It should, however, also be recognized that while ozone itself may be corrosive, corrosion occurs from too much oxidant, rather than that of a specific type.
Ozone generators required to produce and regulate large amounts of ozone are often quite complex, expensive, require high voltage and current levels and a delicate balancing of power supplies. For these and other reasons, ozone generators are costly and have a poor reputation for dependability. Many existing ozone treatment systems for water simply dissolve as much ozone in the tower water as possible. Generators capable of producing large amounts of ozone are used to develop the maximum possible ozone residual in the tower basin water.
For any biocidal program to be effective, the water must be clean. Therefore, all cooling towers should have a filtration system of some kind, regardless of the biocidal technology used. The finest particles within the system have the greatest relative surface area, and produce the greatest chemical activity. They absorb chemicals used for disinfection or corrosion control, and also consume ozone. As such, and for maximum effectiveness of any water treatment program, particles in the 1-5 micron range, should preferably be removed. Various filter technologies are capable of doing this.
The ozone may be introduced by various methods, including sparging either in the sump itself or in a contacting tower. The contacting tower can also be fed by venturi injection. Another method of introducing ozone is by the aspiration thereof into flowing water with a venturi system. Although this can be effective, it requires a small diameter pipe with limited water volume and specific % pressure differential. When conditions are ideal, the gas and water will only remain mixed for a limited distance, and only then if the pipe is straight and of reasonably small diameter with no bends to increase back pressure.
SUMMARY OF THE INVENTION
According to one aspect of the invention, there is provided a water treatment apparatus for treating water in a device using water as a circulating medium, the apparatus comprising: (a) an extractor line for removing water from the device; (b) o z o n e generation means for producing and conveying a supply of ozone; (c) a contactor member having an entry passage for receiving water from the extractor line and ozone from the ozone generation means, and contacting passages for receiving a water and ozone mixture from the entry passage and configured so as to create turbulence to intimately mix the water and ozone along at least a portion of its length, and preferably its entire length; and (d) a return line for receiving and transporting the water and ozone mixture from the contacting passages back to the device.
According to another aspect of the invention, there is provided a water treatment apparatus for treating water in a cooling tower having a water basin, tower fill elements positioned over the water basin and through which water cascades downward for the purposes of cooling the water, the apparatus comprising: (a) a extractor line for removing water from the water basin for cleansing and purification treatment; (b) ozone generation means for producing and conveying a supply of ozone; (c) a contactor member having an entry passage for receiving water from the extractor line and ozone from the ozone generation means, contacting passages for receiving a water and ozone mixture from the entry passage and configured so as to create turbulence to intimately mix the water and ozone along at least a portion of its length, and an exit passage for the water and ozone mixture; and (d) a return line for receiving and transporting the water and ozone mixture from the exit passage, or multiple outlet passages, back to the top of the tower fill, the ozone being removed from the mixture by air stripping when the ozonated water cascades down the tower fill.
According to yet a further aspect of the invention, there is provided a method of treating water to remove bacterial and other impurities therefrom, the method comprising: (a) conveying a
Abrahams Colin P.
Hoey Betsey Morrison
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