Technical Bulletin No. 0106: A Study of SOx Measurement Procedures and Their Use at Kraft Recovery Furnaces (AQTB)

The presence of acid sulfate aerosols in the ambient air is of special concern in air quality management programs because of their known adverse effect on human respiratory functions. Sulfuric acid, the principal precursor of acid sulfate aerosols, is a known component in flue gas from fossil fuel combustion. The most significant point source emission of sulfuric acid likewise is that from combustion of fossil fuel. The combination of spent cooking liquor with high sulfur content has made it, without evidence, a suspect source of acid sulfate aerosols as well. The matter of defining the possible level of sulfuric acid in kraft recovery flue gas presented peculiar, yet highly significant, measurement problems in that the flue gas contains quantities of sodium sulfate even after highly efficient particulate collection devices. If the sodium sulfate is not separated from the gas stream prior to sample collection for sulfuric acid, the use of most, if not all, measurement methods for sulfuric acid would count sodium sulfate as an acid.