JV Task 124 - Understanding Multi-Interactions of SO3, Mercury, Selenium, and Arsenic in Illinois Coal Flue Gas

Abstract

This project consisted of pilot-scale combustion testing with a representative Illinois basin coal to explore the multi-interactions of SO 3 , mercury, selenium and arsenic. The parameters investigated for SO 3 and mercury interactions included different flue gas conditions, i.e., temperature, moisture content, and particulate alkali content, both with and without activated carbon injection for mercury control. Measurements were also made to track the transformation of selenium and arsenic partitioning as a function of flue gas temperature through the system. The results from the mercury-SO 3 testing support the concept that SO 3 vapor is the predominant factor that impedes efficient mercury removal with activated carbon in an Illinois coal flue gas, while H 2 SO 4 aerosol has less impact on activated carbon injection performance. Injection of a suitably mobile and reactive additives such as sodium-or calcium-based sorbents was the most effective strategy tested to mitigate the effect of SO 3 . Transformation measurements indicate a significant fraction of selenium was associated with the vapor phase at the electrostatic precipitator inlet temperature. Arsenic was primarily particulate-bound and should be captured effectively with existing particulate control technology.