An updated acid dew point temperature estimation method for air-firing and oxy-fuel combustion processes.

The estimation of acid dew point temperature (T adp ) of flue gas, which is mainly determined by SO 3 concentration and steam concentration (C H2O ) in flue gas, is crucial for coal-fired boiler system design. In this work, the heterogeneous and homogeneous effects for the conversion of SO 2 to SO 3 in the oxy-fuel flue gas have been examined. An updated formula for T adp estimation of flue gas was proposed, which is: T adp = 186 + 20 lgC H 2 O + 26 lg ( C SO 2 * ( 127.65 C SO 2 * − 0.585 + lg Aar × α fly C SO 2 * 1 2 × ( 15.191 + 0.071 Fe + 0.044 Al − 0.058 Ca − 0.117 Mg ) × 10 − 2 ) ) The updated formula shows that the main effects of the T adp were the steam concentration, initial SO 2 concentration (C SO2 , ppm), ash content of raw coal (A ar , %), fly ash proportion of the inherent coal ash (α fly , %), main mineral contents of coal ash (Fe, Al, Ca, Mg, g/kg). The formula was then fully validated by a large amount of data obtained from laboratory-scale experiments, pilot-scale experiments and industrial scale coal-fired power plants. The results showed that, the heterogeneous effect for the conversion of SO 2 to SO 3 contributed to 1.33 to 20.86% of the total SO 3 formed, smaller than the homogenous effect. Furthermore, the influence of the heterogeneous effect for oxy-fuel process was 1.2–1.6 times larger than that for the conventional air-fired process. The accuracy of the updated formula was proven much higher than the conventional empirical formula for air-firing combustion. The relative deviation of the calculation for oxy-fuel combustion by the updated formula was < 7.8%. [ABSTRACT FROM AUTHOR]