Corrosion of evaporator tubes in low emission steam boilers

摘要: Purpose: of this paper is to reveal the mechanisms corrosion processes outer surfaces low-emission steam boiler evaporator tubes. Examinations were performed find reasons different susceptibility tubes situated at combustion chamber on various levels. Design/methodology/approach: conducted several segments O 57 x 5.0 mm made 16M (16Mo3) steel grade. Segments taken from level 10 meters and 18 bottom coal fired after two years operation. Microstructure degradation base material was estimated. Metallographic evaluation scale morphology, its micro sites chemical composition analysis distribution elements cross sections have been performed. Findings: Eexaminations indicated that reduction wall thickness considerable m, when m small. The morphology scales consisted external layer which porous weakly connected tube surface, internal layer, dense adherent metal. In these layers bands reach in sulfur detected. sulfide seems be main mechanism surface m. Research limitations/implications: Corrosion water boilers a result reaction with aggressive substoichiometric environment contains sulfur. flue gases changes along wall. exact compound has not determined study. Practical implications: Prevention can achieved by changing operation conditions or replacement materials. first mentioned action limited accurate burner’s adjustment introduces flow additional air walls create curtain between reducing surface. These efforts often are insufficient. more resistant Cr rich Cr-Ni possible but other problems appear high costs installation low heat transfer coefficients such Knowing allows adjusting process emission boilers. Originality/value: Information available literature does clearly indicate what dominant parts chamber. current study shows most dangerous for