Particulates from a Stoker Boiler Fueled by Alternative Fuels

MADIE HOLLE, Ibrahim Al-Naiema, Claire Meyer, Elizabeth Stone, University of Iowa

     Abstract Number: 649
     Working Group: Combustion

Abstract
To reduce the use of coal, local biomass and pre-consumer waste have partially or completely offset coal in the heating and cooling of the University of Iowa campus via an industrial boiler. Pre-consumer waste paper and plastic were densified into energy pellets to convert these waste streams into a usable form for energy production. This research examines the energy-based emission factors of various hazardous air pollutants, including particulate matter (PM), particulate metals, dioxins and furans, and polycyclic aromatic hydrocarbons (PAH) for coal and these alternative fuels from 2015 to present. These hazardous air pollutants can cause adverse health effects in surrounding community members, especially those with underlying health conditions, and can cause long-term environmental damage. Samples were collected using standard stack testing methods equipped with an electrostatic precipitator, a baghouse filter, and/or a sorbent injection system. Co-firing coal and miscanthus grass decreased emissions of PM, and many particulate metals compared to coal, with minor changes to PAH emissions. Co-firing coal and energy pellets increased emissions of PM, decreased nearly all metals, and increased PAHs compared to coal. Due to challenges in attaining stable co-firing conditions, this practice was suspended in favor of fueling the boiler entirely with energy pellets. When firing the boiler with 100% energy pellets, PM emissions increased compared to coal. There were both increases and decreases in emissions of metals and PAHs, suggesting variability in these emissions with pellet composition. This research demonstrates how the magnitude and composition of emissions vary from an industrial boiler as coal is offset with alternate fuels.