Optical Property Measurements of Mixed Coal Fly Ash and Particulate Carbon Aerosols Likely Emitted during Activated Carbon Injection for Mercury Emissions Control

Abstract

The most mature technology for controlling mercury emissions from coal combustion is the injection into the flue gas of powdered activated carbon (PAC) adsorbents having chemically treated surfaces designed to rapidly oxidize and adsorb mercury. However, carbonaceous particles are known to have low electrical resistivity, which contributes to their poor capture in electrostatic precipitators (ESPs), the most widely used method of particulate control for coal-fired power plants worldwide. Thus, the advent of mercury emissions standards for power plants has the potential for increased emissions of PAC. Our previous analyses have provided estimates of PAC emission rates resulting from PAC injection in the U.S. and extrapolated these estimates globally to project their associated climate forcing effect. The present work continues our examination by conducting the first comparative measurements of optical scattering and absorption of aerosols comprising varying mixtures of coal combustion fly ash and PAC. A pa...