Abstract: An air preheater (APH) temperature control system, including at least a first APH or combustion/secondary air bypass duct in metered communication with a combustion air inlet duct and a secondary air duct, adapted in use to bleed a portion of the combustion air as secondary air bypass from the air inlet duct upstream of the APH 100 for reintroduction downstream into the secondary air duct, and a flow control device for metering or controlling volumetric flow of the secondary air bypass and tempering primary air flow in use operative to maintain the flue gas outlet temperature at or above a desired minimum predetermined temperature for the incident flue gas volumetric flow exiting the APH alone or in conjunction with other tempering means maintaining mills outlet temperature within a safety range of T10MIN to T10MAX.

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.

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.