Breen Energy Solutions developed a patented technology to measure the concentration and Dewpoint temperature of SO3 and other Sulfur derived condensable species in combustion flue gases.
Sulfur in fossil fuels oxidizes during combustion to form Sulfur-Dioxide (SO2). A portion of this SO2 further oxidizes to Sulfur-Trioxide (SO3). The SO2 to SO3 oxidation occurs in the furnace, across the ash deposits in the convective pass and across the Selective Catalytic Reduction (SCR) catalyst (if present for NOx removal). Typically, about 1% of the SO2 converts to SO3 in the furnace and convective pass. A further 0.5 to 3% conversion can occur across the SCR subject to catalyst design and operating temperatures. The SO3 in the gas phase combines with moisture (H2O) to form Sulfuric Acid (H2SO4). This conversion starts at 800 DegF and is completed below 400 DegF where all the SO3 is now H2SO4. The H2SO4 can further react with elements and compounds such as Ammonia (NH3) to form Ammonium Bisulfate (NH4HSO4) and Sodium (Na) to form Sodium Bisulfate (NaHSO4) which are also condensable compounds. The H2SO4 may also react with Ash-Alkali to form non-condensing compounds such as Ammonium Sulfate, Sodium Sulfate, Potassium sulfate among others.