The fate of sulphur during oxy-fuel combustion of lignite

This work focuses on the sulphur chemistry in oxy-fuel combustion of lignite. Comparison is made with air-fired conditions, and the main combustion products containing sulphur (ash, SO2, SO3 and H2S) are examined by modelling and experimental data. The conversion of fuel-S to SO2 is lower in oxy-fuel than in air-fuel conditions and the SO2 concentration per unit energy supplied is therefore reduced. The modelling shows that the SO3 concentration is about four times greater than the concentration in air-firing. High SO3 and H2O contents in the oxy-fuel flue gas during wet recycling increase the acid dew-point by 20 to 30 K.