Identification of mechanisms and intensity of corrosion/erosion processes of the heated combustion chambers` surfaces using internally cooled multi-material diagnostic probes: evaluation of the application potential of the probes from the point of view of conventional power units and thermal waste treatment installations

The article presents the research results on identifying mechanisms and the intensity of corrosion processes occurring in the low-emission OP-430 boiler using a new internally cooled three-material diagnostic probe. This probe was located at the height of the low-emission burners in the evaporator combustion chamber. It included three cooled pipes made of P265GH, 16Mo3 and 10CrMo9-10 steel and the exposure time in actual boiler operating conditions lasted 120 h. After removing the probe, microstructural analyses were taken from the areas directly adjacent to the evaporator wall, the place most exposed to low-emission corrosion. The second sample was taken from the probe's tip, approximately 450–500 mm from the evaporator wall, characterized by a completely different exhaust gas temperature and composition of the working atmosphere. The scope of the research included the chemical and phase composition analysis of ash deposits and microstructural aspects of corrosion processes occurring in the analysed materials. Differences were found in the corrosion behaviour and intensity of the tested materials regarding their type and sample location, which confirm the practical usefulness of the proposed new construction of diagnostic multi-material probes.