(487b) Laboratory-Scale Study of Fine Particle Formation and Mercury Speciation During Oxy-Coal Combustion

Coal combustion is the largest single contributor to global anthropogenic CO₂ emissions, contributing ~50% of electricity generation in the United States and 42% of total CO₂ emissions. Several options exist for capturing CO₂, and oxy-coal combustion is a means for increasing the concentration of CO₂ in flue gas and minimizing parasitic losses in supplying CO₂ ready for geological sequestration or conversion to useful products. Ongoing work at the Aerosol & Air Quality Research Laboratory (AAQRL) at Washington University in St. Louis (WUStL) has focused on the oxy-coal combustion modality as a basis for producing flue gas with CO₂ of sufficiently high purity for direct conversion and sequestration applications, without expensive gas separation.

Laboratory-scale furnaces are used for various aspects of oxy-coal combustion, including a drop-tube furnace for studying the effect of flue-gas recycle on fine particle formation and mercury speciation, and a furnace aerosol reactor for synthesizing nanostructured catalysts for CO₂ photoreduction. The effect of gas composition on the sub-oxide formation in oxy-coal combustion systems will be discussed. As flue gas recycle may potentially impact the volatilization rates, this is also examined for submicrometer particle formation in contrast to systems with no recycle. The presentation will also discuss the resultant size distribution of particles and mercury speciation for a variety of coal seams from China and the United States in oxy-coal combustion systems, and contrast to those from conventional air combustion systems. Results indicate that the combustion in an oxygen-carbon dioxide environment suppresses the volatilization rates, resulting in a decrease in the fine particle fractions.