摘要:
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° 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.
摘要:
An improved method for removing scale, sludge, corrosion and other debris and deposits from the interior of a heat exchanger vessel such as a nuclear steam generator, includes generating pressure pulses in a non-corrosive, strongly basic, amine-containing chemical cleaning agent in aqueous solution after the agent has been introduced into the interior of the vessel to create shock waves in the liquid for dislodging, dissolving and fluidizing sludge and corrosion products. The chemical cleaning agent is an aqueous solution containing at least one of the group of lower alkyl amines, e.g., dimethylamine, ethylamine, 1,2-diaminoethane, or diaminopropane, lower alkanol amines, e.g., ethanolamine, 2-methyl-2-amino-1-propanol, and 5-aminopentanol, lower alkoxy alkyl amines, e.g., 3-methoxypropylamine, and cyclic diimines, e.g., 1,10-phenanthroline, 2,9-dimethyl-1,10-phenanthroline, 4,7-dimethyl-1,10-phenanthroline, 2,2'-bipyridine, and 4,4'-bipyridine, and terpyridine, or combinations thereof. The method further includes simultaneously recirculating the chemical cleaning agent through a filter assembly during the pressure pulsing operation in order to remove fluidized sludge and corrosion products dislodged by the pressure pulsing and chemical action, thereby affording them no opportunity to resettle back onto the surfaces of the heat exchanger vessel and interfere with the chemical cleaning of the vessel. The method reduces not only the time required for a particular chemical cleaning agent to effectively clean the vessel, but further reduces the number of times such chemicals need to be introduced into the vessel, which in turn results in the production of less radioactive liquid waste products, and minimizes new corrosion through use of relatively non-corrosive cleaning agents.
摘要:
A method for dislodging and dislocating scale, sludge, corrosion and other deposits from heat transfer equipment surfaces, such as boiler and heat exchanger surfaces in steam generation systems, which are in contact with aqueous systems. This invention relates to the introduction of an aqueous chemical cleaning solution into the heat exchanger vessel. The aqueous chemical cleaning solution contains a non-corrosive carrier agent and/or a non-corrosive intercalation agent. The carrier agent has the ability to penetrate the matrix of the sludge, scale and other deposits, and the intercalation agent causes the sludge, scale and other deposits to fracture and break apart. This invention relates to generating a series of pressure pulses within the non-corrosive aqueous chemical cleaning solution to create shock waves for dislodging, dissolving and fluidizing sludge and corrosion products. This invention relates to the soaking of scale, sludge and other deposits in aqueous chemical cleaning solutions to dislodge and dislocate the sludge, scale and other deposits. This invention further relates to an operation utilizing a high velocity jet of water, the water containing a chemical cleaning additive, to dislodge and dislocate scale, sludge, corrosion and other deposits from the interior surfaces of heat exchanger vessels, in particular, the interior of the secondary side of nuclear steam generators. The aqueous chemical cleaning solution utilized in the aforementioned soaking operation and the chemical cleaning additive contained in the aforementioned jet of water, may be a chelate agent or a non-corrosive chemical cleaning agent containing a carrier and/or intercalation agent. The non-corrosive chemical cleaning agent may be a lower alkyl amine, e.g., dimethylamine, lower hydroxyalkyl amine, e.g., ethanolamine and pentanolamine, or cyclic dimines, e.g., 1,10-phenanthroline, 2,9-dimethyl-1,10-phenanthroline, 2,2'-bipyrindine and 4,4'-bypyridine, or combinations thereof.
摘要:
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.
摘要:
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.
摘要:
A method of encapsulating radioactive waste including withdrawing radioactive liquid having a retardant therein from a source. The retardant may including borates, or other additives, which retard the setting of cements by preventing hydration at cement particles in the mix. The liquid is mixed with ordinary Portland cement and subjected to long term shear far in excess of that needed to form ordinary grout. The use of shear to overcome set retardation, and similarly, the deliberate regulation of acceleration of set in hydraulic cement pastes by the utilization of retardants plus shear produces a thixotropic paste with extreme moldability which will not bleed, and finally sets more rapidly than can be expected with normal mixing to form a very strong product.