Dominion Engineering, Inc.

Michael W Rootham

Robert Douglas Varrin, Jr

Sotaro Kaneda

Naonobu Sasada

An improved scale conditioning composition and method is disclosed that results in improved dissolution and disruption of tube scale, hardened sludge and other deposits composed primarily of highly densified magnetite such as those found in heat exchange vessels, particularly steam generators. After treatment with the advanced scale conditioning composition, these magnetite rich deposits are more easily removed using known and commercially available high pressure hydro-mechanical cleaning techniques. The present invention further provides effective cleaning in a short period of time and at relatively low temperatures, while reducing the amount of waste produced and reducing the resulting corrosion of carbon and low alloy steel components within the steam generator during the cleaning process.

Scale conditioning agents and treatment method

The present invention provides an improved scale conditioning composition and method that results in improved dissolution and disruption of tube scale, hardened sludge and other deposits composed primarily of highly densified magnetite such as those found in heat exchange vessels. After treatment with the advanced scale conditioning composition, these magnetite rich deposits are more easily removed using known and commercially available high pressure hydro-mechanical cleaning techniques. The present invention further provides effective cleaning in a short period of time and at relatively low temperatures, while reducing the amount of waste produced and reducing the resulting corrosion of carbon and low alloy steel components within the steam generator during the cleaning process.

Scale conditioning agents

An ultrasonic cleaning method for cleaning the film, scale and sludge from internal surfaces of tubes, tubesheets, tube support plates and channel heads of steam generators previously exposed to water or steam at temperatures of more than 200&deg; C. introduces an ultrasonic transducer or transducer array into the steam generator and submerges the ultrasonic transducer and the surface to be cleaned in water or aqueous solution. Ultrasonic energy is introduced into the water at a power level of 20 watts/gallon or more and at frequencies of from 10 to 200 KHz. An array of transducers is employed to introduce 20 to 60 watts/gallon of water or more into the steam generator. In one practice, the transducer or transducer array is suspended in the steam generator. An array of transducers can be assembled (and later disassembled) in situ where individual transducers or small transducer subassemblies must introduced into the steam generator through small hand holes or other small diameter nozzles. In another practice, the ultrasonic transducer is moved through the water while introducing the ultrasonic energy into the water. Large amounts of ultrasonic energy can be introduced into the water and the energy nodes moved through the water so that the energy can efficiently penetrate into the interior rows of tubes and other internal structures.

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Delmont, PA, United States of America

Michael W Rootham