Partitioning of Harmful Elements in PM₁₀ from Air-and Oxy-Coal Combustion: Iron and Sulfur

Abstract

Adverse health effects of Fe and S in airborne particulate matter (PM) have been reported. However, little work has been done to characterize Fe and S in PM10 from coal combustion. In this study, a sub-bituminous coal (coal A) and a bituminous coal (coal B) were subjected to combustion in a drop tube furnace under air-and oxy-firing conditions. Size distribution and elemental composition of PM10 (PM with aerodynamic diameter 10 μm) were obtained by low pressure impactor and X-ray fluorescence techniques, respectively. The partitioning characteristics of Fe and S in PM10 were investigated. Data shows that particles of ~0.1μm contains the highest concentration of Fe for both coals under different combustion conditions. The concentration of Fe in the ultrafine particle mode decreases when switching from air combustion to oxy-fuel combustion with 21% O2. It increases when the oxygen concentration increases from 21% to 32% O2 during oxy-fuel combustion. Changing combustion conditions has little effects on Fe partitioning in particles >0.3μm. The concentration of S in PM10 increases with decreasing particle size, but changing combustion conditions have inconclusive influence. Fe and S are dominant elements in ultrafine particles, indicating a greater threat to human health.