Demonstrating Compliance with Sub-ppm Acid Mist Limits: Can EPA Method 8 Handle the Challenge?

摘要

EPA Method 8 for measuring SO2 and H2SO4/SO3 has been used for years in the utility industry, but was designed and validated for use at sulfuric acid plants. However, the method is increasingly being specified in operating permits to measure very low levels of SO3 at coal fired power plants and other sources. This paper looks into the capabilities of the method in a typical coal-fired boiler gas stream; focused on the method detection limit (MDL) for Method 8 and several areas where biases arise, especially at low levels of SO3. Areas that are addressed include: experimentally determined MDL, SO2 oxidation bias, titration error, analyst bias, and filter bias. A discussion is also included on potential procedures to improve the accuracy of the method at low SO3 concentrations. All results presented in this paper are preliminary at this time and are subject to further