Protective Oxidation of Boiler Equipment Heating Surfaces with Concurrently Removing Ash Deposits

摘要

— The problem of removing ash deposits appearing on the heating surfaces during fuel combustion has presently been solved only for boilers equipped with a steam- or water-assisted surface treatment system. However, the treatment with steam (water) does not guarantee efficient removal of deposits from the heating surfaces nor does it guarantee efficient protection of the cleaned heating surfaces from corrosion. According to the applied technology, ash deposits are removed from the heating surfaces by subjecting the latter to steam blasting with concurrent thermochemical oxidation of the cleaned surfaces. In the framework of searching for ways of making both stages of this process more efficient, the possibility of treating the equipment surfaces that need cleaning with vapor–aerosol compositions containing ammonium acetate solution in the aerosol phase is considered. Such treatment yields a double effect: first, ash deposits are more efficiently loosened during thermal decomposition of ammonium acetate and, second, the cleaned metal surfaces are uniformly oxidized during the thermolysis of acetate iron complexes generated in the solution film that is produced on the metal surface when aerosols precipitate on it. The protective oxide film produced on the surface smooths the metal surface roughness, thereby weakening the cohesion of ash and tar deposits with it, due to which it becomes possible to increase the boiler operation time between its treatment outages.