Influence of temperature and activated carbon injection on organic components of condensable particulate matter in coal combustion for emission control

Conventional air-pollution control devices in coal-fired power plants cannot effectively remove condensable particulate matter (CPM), which contributes considerably to fine particulate emissions. This study investigated the formation characteristics and temperature-dependent control of CPM organic components under laboratory-scale coal combustion conditions using an activated carbon sorbent layer simulating injection conditions. Flue gas temperatures of 110°C, 140°C, and 170°C were examined with and without activated carbon injection (ACI) at 200 mg/Nm3. Without ACI, the CPM organic concentrations increased slightly with temperature, while n-alkanes accounted for approximately 2.16%-6.38% of the total CPM organic matter. At all three temperatures, lower-carbon-number n-alkanes contributed more notably to the CPM organic fraction in both the presence and absence of activated carbon. ACI significantly reduced CPM organic matter at 110°C and partially reduced it at 140°C, but had a negligible effect at 170°C. Lower-carbon-number n-alkanes were readily reduced at lower temperatures such as 110°C and 140°C, whereas higher-carbon-number species were likely to condense upstream of the sorbent, limiting their interaction with activated carbon. These findings indicate that the effectiveness of ACI in controlling CPM organic matter is highly sensitive to flue gas temperature, highlighting the importance of controlling gas-phase precursors prior to condensation to mitigate CPM emissions from coal combustion.Implications: Organic condensable particulate matter emitted from coal combustion contains hazardous compounds and is poorly captured by conventional particulate controls. This study demonstrates that powdered activated carbon injection reduces CPM organics by approximately 23% at 110°C but has little effect at 170°C. This suggests the importance of controlling flue-gas temperature and volatile organic precursors before condensation occurs. Power plant operators and regulators can use this information to optimize activated carbon injection and develop integrated CPM control strategies to meet future emission standards.