Chemistry: electrical and wave energy – Processes and products – Electrostatic field or electrical discharge
Patent
1993-03-23
1994-09-06
Niebling, John
Chemistry: electrical and wave energy
Processes and products
Electrostatic field or electrical discharge
204196, 204231, C23F 1300, C23F 1500
Patent
active
053445317
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a prevention or control method of aquatic attaching fouling organisms attaching and breeding on water contact surfaces of intake passes of power stations, iron foundries, oil refinery plants, ere, using water such as brine as cooling water, intake facilities such as screens, and submerged steel and concrete structures to be submerged and constructed in sea water such as piers, steel piles and steel pipe piles, and equipment used for the method.
BACKGROUND ART
Aquatic organisms inhabiting in water such as bacterias, seaweeds, shellfishes, etc, attach and breed on water contact portions of various harbor facilities such as quays, piers, platform piers, buoys, and submerged structures such as ships and greatly lower the functions of such facilities and submerged structures.
The quantity of cooling water or power generation water for various intake equipment such as plant intake passes, intake pipes and screens, which is used as cooling water in steam power stations, atomic power stations, iron foundries, oil refinery plants, etc. or as power generation water of power stations, ranges from dozens of thousands of cubic meters to hundreds of thousands of cubic meter per hour and is extremely great. Therefore, maintenance management of the intake equipment is of great importance. The essential points of this maintenance management are corrosion control of the facilities and control of attachment of aquatic organisms attaching and breeding on the surfaces of the intake facilities in the same way as in the submerged structures. Attachment and breeding of the aquatic organisms are causes for the occurrence of various troubles in the normal operations of equipments and facilities.
Excellent corrosion prevention engineerings such as the development of corrosion resistant materials, the progress in coatings and cathodic protection have been developed and put into practical applications as corrosion prevention control means of these submerged structures and Intake facilities.
On the other hand, prevention means against attachment of aquatic fouling organisms such as marine creatures have long been employed. In other words, the following means have been proposed:
All of these methods are effective as prevention means against attachment of marine organisms, but they are anti-fouling means or methods comprising principally the formation of the toxic ions such as chlorine, hypochlorite, copper, mercury, tin, and there is the possibility that these toxic ions induce secondary environmental pollution. The formation and use of these toxic ions require great expenses for installations for keeping a suitable concentration or density for a long service life and for the maintenance and management of the installations; but mainly because they use the toxic ions and may result in environmental destruction rather than because of expenses, the use of such installations tends to be inhibited.
Chlorine and hypochlorites can be charged easily, but the concentration management is difficult. If any reducing agents or substances exist in water, the consumption amount of chlorine becomes greater, and the anti-fouling effect cannot be expected in some cases. A great deal of labor and expenses are necessary for maintenance and management of a chlorine generation apparatus and its concentration management, and secondary environmental pollution is not avoidable. Therefore, the use of such compounds is now avoided as much as possible.
Anti-fouling coatings or paints mostly contain metal pigments generating toxic ions, and comprise mainly mercury, mercury compounds, copper, copper alloys and their compounds. Recently, these materials have been replaced gradually by organic stannous compounds (stannates), but the service life as the coating is about 2 years. These paints involve the problem of low durability resulting from impact, wear and tear. Furthermore, the use of such coatings tends to be inhibited from the aspects of environmental pollution and safety in the same way as in the case of chlorine.
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REFERENCES:
patent: 3766032 (1973-10-01), Yeiser
Kuwa Morihiko
Saito Kiyomi
Nakagawa Corrosion Protecting Co., Ltd.
Niebling John
Phasge Arun S,.
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