System for controlling corrosion in an environment in which thin layers of low-pH corrosive fluids are formed
AssigneeElectric Power Research Institute, Inc.
InventorsBarry C. Syrett, Gerhardus H. Koch, Neil G. Thompson
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Abstract
A system for preventing corrosion of a metallic surface in an environment in which a corrosive condensate with a pH of less than about 3 tends to form on the surface exposed to the environment. The system includes an absorbent lining formed from a concrete material that has a chemical resistance to a low pH and that increases the pH of the environment at the underlying metallic surface. The system further includes a counterelectrode and an electrochemical potential control means connected in electrical circuit with the metallic surface. An electrical potential is maintained upon the metallic surface sufficient to effect cathodic protection.
Claims7
A method for cathodic protection of a metallic surface comprising:
- applying to the side of the metallic surface facing a flue gas and on which a corrosive condensate with a pH of less than about 3 would occur on the metallic surface in the absence of the method, a layer of an acid resistant concrete that has a chemical resistance to a low pH and that chemically affects the corrosive condensate by increasing its pH to a value where cathodic protection is feasible;
- absorbing the corrosive condensate in said layer of acid resistant concrete;
- and
- inducing an electrochemical potential between said metallic surface and the absorbed condensate in said layer sufficient to effect cathodic protection of the metallic surface.
An apparatus for preventing corrosion of a metallic surface exposed to a flue gas, comprising:
- an acid-resistant concrete disposed on the metallic surface and exposed to the flue gas wherein a thin layer of corrosive condensate with a pH of less than about 3 tends to form on said concrete, said concrete forming a lining capable of absorbing the corrosive condensate and having a chemical resistance to a low pH, and chemically affecting the corrosive condensate by increasing its pH before it reaches the metallic surface to a value where cathodic protection is feasible;
- a counterelectrode in contact with said concrete and spaced from said metallic surface;
- and
- electrochemical potential control means connected in an electrical circuit between said couterelectrode and said metallic surface for maintaining an electric potential upon said metallic surface sufficient to effect cathodic protection of said metallic surface by passing a current from said counterelectrode to said metallic surface through the corrosive condensate absorbed by said lining.
Dependencies are inferred from the claim text.