AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Measured Optical Absorption and Scattering Coefficients of Agglomerates of Coal Fly Ash and Powdered Activated Carbon
TIAN XIA, Akosua Miller, Herek Clack, University of Michigan
Abstract Number: 394 Working Group: Carbonaceous Aerosols in the Atmosphere
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 less efficient capture during electrostatic precipitation, the most widely used method of particulate control for coal-fired power plants worldwide. Our previous analyses provided estimates of likely PAC emissions resulting from the use of PAC injection as a mercury emissions control technique, and their potential climate forcing impact. The present work supports the continued examination of the potential climate forcing effects of fugitive powdered mercury sorbents by measuring optical absorption and scattering coefficients of fly ash and mixed fly ash-PAC aerosols as a function of PAC concentration. The aerosols are elutriated from a partially fluidized bed and sampled and characterized using a novel photoacoustic extinctiometer. SEM imagery of the collected aerosols provides additional insight into the agglomeration state of the mixed aerosols. These results provide the optical property data base needed to evaluate the climate forcing impact of fugitive PAC and establish allowable PAC collection efficiencies and emission rates for coal-fired power plants in the future.