Effect of Coordinated Air Pollution Control Devices in Coal-Fired Power Plants on Arsenic Emissions

摘要

An arsenic emission study was performed, at nine coal-fired power plants in China and the U.S. that are equipped with various air pollution control devices (APCDs). On average, over 90% of arsenic in the flue gas is captured by the dry particulate matter collection system. Less than 3% of arsenic remains in the boiler slag, and 3% is captured by the desulfurization system. Another 1% is captured by wet precipitators. The remaining arsenic is emitted from the stack. Ultralow-emission technology with a low-temperature economizer before the electrostatic precipitator (ESP) promotes the capture of more arsenic compounds. It was found that reactions between arsenic and the denitrification catalyst make it difficult to reach a perfect arsenic mass balance in a power plant, excluding plants that are equipped with a hot ESP installed before the selective catalytic reduction system. Arsenic speciation greatly depends upon the temperature of the flue gas and the location of the measurement. There are no significant differences between U.S. and Chinese coals with regard to the behavior, of arsenic during combustion and its interaction with power plant APCD systems.