Corrosion of alumina and mullite hot gas filter candles in gasification environment

Reliable fuel gas cleaning is required to meet environmental regulations as well as to prevent corrosion and erosion of downstream components. The aggressive process environment in biomass-gasification power generation systems or in biofuels production systems causes corrosion in the ceramic hot gas filter candles used to clean the fuel gas. Therefore, in order to improve the reliability and durability of filters, the influence of steam, ash, hydrogen sulfide, and alkaline metals on the corrosion processes was studied for alumina and mullite filter candles fabricated by Pall Schumacher. Exposure to these contaminants effects the chemical composition of the binder phases resulting in exchange of alkaline metals and alkaline earth metals. Analyses by energy dispersive X-ray spectroscopy demonstrate the negative effect of silicon containing binder phases. These effects are discussed and it is shown that the usage of silicon-free binder phases in hot gas filter candles for gasification processes is promising.