Corrosion behaviour of ceramic filter candle materials for hot gas filtration under biomass gasification conditions at 850°C

A compact version of a gasifier realised by integrating the fluidised bed steam gasification of biomass and the hot gas cleaning and conditioning system into one reactor vessel was the aim of the ‘UNIQUE’ project. Hot gas filtration systems are designed to protect the gas turbine or fuel cell from erosion and particle contamination, clean the process gases for production of synthetic fuels and indirectly improve efficiency and decrease maintenance. Knowledge of critical points of the porous ceramic filter elements is essential for the successful operation of the hot gas filtration. The corrosion behaviour of ceramic filter materials in contact with different biomass ashes under simulated gasification conditions was investigated for aluminium oxide, based SiC with mullite filter layer and mullite based filter candles. Analyses by energy dispersive X-ray spectroscopy show the influence of potassium on filter candle materials.