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Surface-active amines and methods of using same to impede corrosionRelated Patent Categories: Compositions, Preservative Agents, Anti-corrosionSurface-active amines and methods of using same to impede corrosion description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20070187646, Surface-active amines and methods of using same to impede corrosion. Brief Patent Description - Full Patent Description - Patent Application Claims
FIELD OF THE INVENTION [0001] The present invention relates to surface-active amines that impede corrosion on metal surfaces, corrosion-resistant apparatuses comprising the surface-active amines, methods of identifying the surface-active amines using electrochemical quartz microbalance (EQCM) in combination with buffered solutions and methods of using the amines to impede corrosion of metals. BACKGROUND OF THE INVENTION [0002] Contaminates such as dissolved oxygen and carbon dioxide promote corrosion of metal surfaces. For example, under laboratory conditions, iron has a tendency to corrode in water in the absence of oxygen because iron is less noble than hydrogen, however, the ferrous hydroxide formed by iron and water elevates the pH by providing hydroxide ions and ferrous ions. This reduces the amount of hydrogen ion which tends to retard corrosion. Therefore, under such laboratory conditions, the reactions that cause iron corrosion are self-limiting. In contrast, however, in industrial systems, where oxygen is present, ferrous hydroxide is unstable and ferric hydroxide is formed. Unlike ferrous hydroxide, ferric hydroxide is not a corrosion inhibitor. [0003] Corrosion of metal surfaces can cause substantial damage to various components of a wide variety of products and systems. The damage is typically characterized by pitting and/or gouging of the metal surfaces and/or general wastage. Furthermore, in the case of steam generating systems, for example, oxides from corrosion of metals and thermally insoluble compounds from salt impurities introduced into the systems results in harmful and unwanted deposition of such products on performance critical components of the system, particularly within two phase regions of steam generating components. Such metals include steel (e.g. low carbon steel), iron, copper, nickel, chromium, aluminum and like alloying components, resulting in their respective oxides in various states and morphologies and further including binary and ternary mixed oxides, system design and thermodynamic conditions. Such impurities include, by way of example, calcium, magnesium, sodium, potassium, aluminum, lead, chloride, silica and sulfate and salts thereof. [0004] The consequences of such corrosion may be quite dramatic. For example, in steam generating systems, failure of condensate return lines, feedwater piping, condensate receivers, pumps, heaters, and/or other equipment associated with steam generating and/or hot water heating systems may result from corrosion. Ultimately, the corrosion reduces the energy efficiency of the systems, as well as the water quality. Moreover, the damage caused by the corrosion increases the costs associated with operating and maintaining the systems while reducing the reliability and effectiveness of the systems. Additionally, various salts may be introduced as impurities into steam generating systems. For example, condenser cooling water inleakage may be the greatest or most common source. Impurities may be introduced in the form of chemical additives, ion exchange media, welding residuals, grinding operations, desiccants and related construction/maintenance functions. These introduced impurities include, for example, without intending to be limited thereto, calcium, magnesium, sodium, potassium, aluminum, chloride, silica, and sulfate, and insoluble salts, such as for example, without limitation, calcium sulfate and aluminum silicate. These impurities are commonly reported as solids in the surface analysis of steam cycle materials. Further, carbon dioxide that dissolves in water causes the pH to be depressed and results in the formation of carbonic acid. Carbonic acid promotes the iron corrosion reaction by supplying the reactant hydrogen ion. [0005] Specific consequences of corrosion are particularly well illustrated in the case of pressurized water nuclear reactors. In a pressurized water nuclear reactor, fission of the nuclear fuel is used to heat water which is held in a pressurized loop so as to prevent the water from boiling. This pressurized loop is referred to as the primary coolant system. The heated pressurized water is passed through the inside of a number of, straight or U-shaped tubes in a steam generator, consistent with once-through or recirculating designs, respectively. Water in the secondary circulation system is passed over and around the outside diameter of the tubes containing the pressurized water. Heat is transferred to the water contained in the secondary circulation system. Because the water in the secondary circulation system is not held under similar high pressure, the transferred heat causes the formation of steam in the secondary circulation system. This steam is used to turn turbine-generator systems which produce electrical energy. Once heat has been transferred to the secondary circulation system, thereby cooling the pressurized water in the primary circulation system, the pressurized water is recirculated back to the reactor core where it is heated again. After turning the turbine, the steam created in the steam generator is cooled by a condensing system returning it to a single phase liquid state. [0006] Corrosion products in the steam generator can lead to a variety of problems including reduction of steam production, loss of efficiency or increased heat-rate, and lower net electrical output. Furthermore, deposition and accumulation of corrosion products on steam generator components can promote locally high steam qualities or void fractions that permit extreme accumulation of other contaminants, such as sodium, chlorides, sulfates and other caustic or acid forming species, all of which can lead to tube cracking, pitting or degradation through intergranular and transgranular modes of attack. Tube degradation caused by corrosion, stress cracking and/or deposit formation occurs in a number of locations within the steam generator, including the junction of the tubes to the tubesheet, the junction of the tubes and support plates, at the top of tubesheets within sludge layers, and along the freespan tube surfaces within thick/and or dense tube scales. [0007] Structural components of steam generators can be degraded by various modes of attack including abnormally high general corrosion and flow accelerated corrosion. Such components may include steam separator systems, structural plates, tube support plates and specifically the tube Ian areas limiting freedom of movement for the tubes. Degradation of the latter can give rise to enhanced degradation by flow induced fretting or wear of the thin-walled tube. [0008] Steam carryover of steam formed oxides and compounds often result in deposit formation on high and/or low pressure steam turbines, giving rise to loss of efficiency and/or creating locally corrosive environments as steam expands across the turbine. Such carryover can be enhanced by high transport rates of metals and their oxides from corrosion in the feedwater to the steam generator, high mechanical carryover due to ineffective steam separators resulting from a fouled state, and from release of heavy deposits formed within the overall steam generator system. [0009] In a nuclear reactor environment, the consequences of tube degradation range from loss of heating efficiency and increased operating costs to potentially untenable situations, such as leakage of radioactivity into the steam generated in the secondary circulation system. Indeed, maintaining the integrity of the pressure boundary between the primary and secondary circulation systems is one of the highest concerns in the nuclear power generation industry. Major tube degradations can result in substantial increases in maintenance and repair cost, extension of maintenance outages, unplanned outages, and overall reduction of capacity factors. [0010] Steam formed deposits within the steam generator system have an adverse effect on the performance of periodic non destructive examination to verify tube integrity by methods such as eddy current, since the deposits can exhibit varying interferences due to magnetic susceptibility of the deposit compounds, deposit thickness, density, and deposit discontinuity on the outer tube surface. Therefore, such deposits can increase inspection requirements and give rise to ambiguity in the data interpretations. In contrast, inspections of clean tube surfaces improve inspection efficiency, enhance confidence in the data interpretation and minimize the probability of unidentified degradations. [0011] Consequently, there is a significant need to minimize corrosion of metal surfaces, whether it be in an industrial setting or elsewhere. Specifically, there is a need for chemistries having benefits beyond conventional alkalizing treatments, such as chemistries exhibiting enhanced corrosion inhibiting properties, such as the surface active amines of the present invention. [0012] In addition to the safety aspects of minimizing corrosion and deposit formation, there are significant cost benefits. For example, taking the case of steam generating systems as being merely illustrative, minimization or elimination of corrosion and deposit formation in the secondary circulation system can prevent unscheduled outages to clean, replace or repair steam generator components. Chemical cleaning operations of steam generators may cost up to ten million dollars and so, the ability to reduce the frequency of such cleanings can greatly decrease the maintenance cost of the steam generator. Flow accelerated corrosion within steam generators can also lead to large repair or replacement costs for components most susceptible to such corrosion, such as feedwater inlet baffles, steam separators, feedwater inlet headers and tube support plates. It is not uncommon for flow accelerated corrosion to result in expenditures of several million dollars in periodic replacement and repair of such components. Finally, accelerated degradation of steam generators and major components can require premature and untimely replacement decisions for the entire steam generator, which typically cost several hundred million dollars and require a lengthy plant outage. [0013] Previously disclosed chemical treatments to reduce corrosion may generally be divided into two classes: (1) classic filming inhibitors, which form a protective barrier between the metal and the corrosive environment and (2) neutralizing amines, which increase the pH of the water and steam phases to reduce the corrosive (acidic) environment. Prior to the present invention, amine treatments fell into the second class of inhibitors, those used to raise the pH of the environment. For example, U.S. Pat. No. 4,192,844 discloses an amine formulation and methods for inhibiting condensate corrosion. The '844 disclosure describes the use of a combination of methoxypropylamine which functions as a neutralizing amine and hydrazine which reacts with and removes oxygen. G. Quandri, et al., "Use of Amines In Once Through Steam Generators", EPRI, Workshop On Use Of Amines In Conditioning Steam/Water Circuits (September 1990), discloses the use of dimethylamine as a conventional alkalizing amine. Such previously disclosed techniques for limiting corrosion, however, have no known efficacy as classic corrosion inhibitors or in directly inhibiting deposition of corrosion products, from a mechanistic perspective. Indeed, conventional alkalizing amines often work in opposition to the minimization of deposit formation by enhancing consolidation of transported corrosion products. [0014] General practice to minimize corrosion is to substantially increase the concentration of amine treatments to further increase the pH, however monovalent cations are removed from steam generating systems through the use of ion exchange systems. High concentrations of alkalizing amines tend to interfere with such removal by binding with the exchange media, in preference over the monovalent cations, causing the release of the cations, sodium, for example, back into the steam generating system. Therefore, optimization of corrosion control by alkalization has practical limits created by compromise of effective removal for corrosive species. [0015] Another example of conventional amine limitations is found in the application of ethanolamine, ETA, due to degradation of the cation resin, particularly higher temperature condensate polisher, resulting in kinetic fouling of the anion resin within the mixed bed polisher system. The impact of the kinetic fouling includes high leakage of sulfates, another corrosive species, premature replacement of the resin system, and less than optimum control over corrosion and corrosion product transport as the amine concentration exacerbates the condensate polisher issues. [0016] Other corrosion and deposit formation inhibitors, such as the amine formulations disclosed in U.S. Pat. Nos. 5,779,814 and 6,017,399 fall outside the classification system discussed above. That is, the methods of the '814 and '399 patents do not function by simple alkalization of the corrosive environment nor do they function by formation of a self assembled monolayer, as is common with classic filming inhibitors. The amines and methods of the '814 and '399 patents control and remove solid deposits from the surfaces of steam generating components by selective sorption of the amine by the solid deposits thereby displacing ions sorbed onto the deposits. [0017] The functioning of the '814 and '399 methods rests upon the known fact that steam formed deposits typically exhibit acidic and basic centres which permit selective sorption of soluble ions, such as sodium and chloride ions. Whether the deposits exhibit acidic, basic or both types of centres depends upon the conditions and environment in which they are formed as well as the chemical composition of the deposit. Generally, the deposit reintrainment is enhanced to compete with deposition processes. (See public presentations listed in G. Quandri, et al. cited above) [0018] The formulation and method of the '814 and '399 patents, however, are not known to exhibit classic corrosion inhibition properties within highly corrosive, strongly acidic, environments caused by concentration of corrosive anions such as sulfates or chlorides. The disclosure of the '814 and '339 patents for deposit control is not based on the intervention of the treatment at the site of corrosion release processes to preemptively preclude deposition, as disclosed in the present invention. [0019] Several other approaches to controlling corrosion in system condensate systems have been previously attempted. For example, some methods have been devised to control acid induced corrosion in such systems. Under this approach, materials are added that are believed to adsorb to the metal surface to form a thin barrier between the metal and the acidic solution. Azoles, such as tolyltriazole, and long chain amines, such as octadecyl amine, have been used in this manner. [0020] Further approaches involve the addition of amines to neutralize the carbonate and thereby increase the aqueous pH. Many different amines are utilized, but some commonly used materials include cyclohexylamine, morpholine, and methoxypropylamine. It has been believed that the high basicity of the amines allows attainment of a higher pH after acid neutralization, and low molecular weight allows greater molar concentration (and thus more neutralization). [0021] Other methods for minimizing the effect of introduced impurities include exclusion and removal on ion exchange media. It is known by a person skilled in the art that steam cycles are treated with alkalizing amines directed at maintaining alkalinity of pH control and reducing agents to promote passivation and minimize corrosion from impurities inherent in the steam generating system such as, for example, iron. G. Quadri, et al., discloses the use of dimethylamine in utility fossil fueled power plant boilers in connection with the conventional manner of steam cycle alkalization, known by a person skilled in the art, to reduce corrosion of ferrous materials. [0022] However, each of the previous approaches to impeding corrosion in steam generating systems is deficient. In particular, previous attempts directed to the use of amines have failed to identify compositions that are effective in industrial settings, and have failed to provide a means for identifying such compositions. Moreover, previous attempts have failed to identify ways to efficiently and cost-effectively impede corrosion in steam generating system. Continue reading about Surface-active amines and methods of using same to impede corrosion... Full patent description for Surface-active amines and methods of using same to impede corrosion Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Surface-active amines and methods of using same to impede corrosion patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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