Systematic Investigation of Deposits in the Boiler of a Semitechnical Rotary Kiln Incinerator—Mineralogical and Chemical Characterization

Mineralogical and chemical characterizations of deposits from the evaporator walls in the boiler of the pilot plant THERESA indicate a correlation of increased corrosion processes with phase transformation in the mineralogical composition. Samples were taken in horizontal and vertical profiles which allow a correlation of the variations in flue gas properties (e.g., temperature, chemical composition) as well as a comparison of the composition in the same boiler zone. The coatings were composed mainly of different sulfates. Phase transformation between calcium- (Ca), sodium- (Na), potassium- (K), and lead- (Pb) sulfates can be observed together with macroscopic corrosion damages at the evaporator walls. These findings should help to give a prognosis of the most endangered areas in the boiler and therefore minimize expenditures for boiler maintenance.