Evaluation of Methodologies for Assessment of SO3 Concentration in Industrial Off-Gas

Abstract

Assessment of acid dew point in industrial off-gas has become increasingly important with strategies for heat recovery and the use of more concentrated gas compositions. Several approaches to acid dew point assessment make use of glassware not compatible with the high fluoride concentrations found in unfiltered gas. In this work, a new and simplistic approach to acid dew point assessment is evaluated side by side with conventional methodology. The new approach captures SO3 in the gas as sulfate onto a solid NaCl trap. Interference from SO2 is avoided since it passes through the NaCl trap unreacted. The trap is then dissolved in water for direct analysis by ion chromatography. The importance of isokinetic sampling was evaluated, and no significant difference in results was observed. This suggests that the acid droplets are small. The method is shown to be promising for acid dew point assessment in industrial off-gas.