Thermodynamische Modellrechnungen zur Entwicklung korrosionsbeständiger keramischer Werkstoffe für den Flüssigascheabscheider in kohlenstaubbefeuerten Energieanlagen

摘要

In the present work thermodynamic calculations using the computer program FACT were carried out under simulated process conditions in order to simulate the cooling behaviour of molten slags and the stability of phases in systems Al2O3-SiO2-ZrO2, Al2O3-Cr2O3-SiO2-ZrO2, Al2O3-Cr2O3-SiO2 und Al2O3-Cr2O3-MgO during contact reactions with molten slags of hard coals in the liquid ash separater of coal combustion plants. As a result of the present thermodynamic calculations as well as the experimental findings materials based on chromcorundum show a safisfactory corrosion resistance to molten slag of hard coals because of the formation of spinel solid solutions acting as a protective coating. In accordance with experiments and thermodynamic calculations an increase of corrosion resistance can be achieved through the increase of Cr2O3 content of the material. In dependece on the ash composition maximum Cr2O3 contents of nearly 100% are not essential in any case.