Abstract View
Positive and Negative Emissions from Cooling Towers
CHRISTOPHER WALLIS, Mason Leandro, Patrick Chuang, Anthony S. Wexler, University of California, Davis
Abstract Number: 526
Working Group: Instrumentation and Methods
Abstract
Cooling towers are widely used in industrial and commercial applications to dissipate heat into the environment by spraying water droplets into air. The evaporation of these droplets cools the water which is then recirculated. Some droplets escape the cooling tower as spray drift and dry down, ultimately resulting in aerosol emission composed of impurities in the recirculating water. EPA AP42 designates these aerosols as PM10 and regulates their emissions. Cooling tower emissions are based on decades-old measurements. Since then measurement technology and cooling tower technology have been improved. We deployed modern aerosol instrumentation on a rack suspended by a crane over cooling towers at three power plants. Nafion dryers on the rack dried the droplets down to their aerosol core. IMPROVE samplers were used to obtain PM10 and PM2.5 mass while a TSI APS measured particle size distribution. In parallel, droplet size distributions were measure by a Phase Doppler Interferometer. Although there are PM10 emissions as described by prior measurements, there are also PM2.5 emissions, not previously appreciated. In addition, cooling towers scrub ambient PM10 and PM2.5 such that under some circumstances the net emissions are negative. Instrumentation, emissions factors and scrubbing efficiencies will be presented.