| abstract |
Processes and methods exist for decreasing emissions of mercury upon combustion of fossil fuels such as coal. Halide salts can be effective when used at locations where they are thermally decomposed to form reactive halogen species, or in combination with an adsorbent material such as activated carbon. Halide salts, such as calcium bromide and sodium bromide, are not typically used at locations downstream of the economizer, where the temperature is typically below around 500 °C, because these salts are non-thermolabile and do not decompose to produce reactive halogen species. However, in flue gas streams that certain flue gas constituents, such as sulfur trioxide or sulfuric acid, reactive halogen species can be produced via chemical reaction. These species react with elemental mercury through various means to form an oxidized form of mercury that is more easily captured in downstream pollution control devices such as particulate control devices or SO2 scrubbers. |