Effectiveness of calcium magnesium acetate as dual SO 2 ‐NO x emission Control Agent

Calcium magnesium acetate (CMA) is an effective dual SO 2 ‐NO x emission control agent. Laboratory‐scale experiments with dry injected particles at a Ca/S molar ratio of 2 [or (Ca + Mg)/S ratio of 6] resulted in SO 2 and NO x removal efficiencies of over 90% at gas temperatures of 950 – 1,250°C in atmospheres containing 12% CO 2 , 3% oxygen, 2,000 ppm SO 2 , and 1,000 ppm NO x during a 1‐s residence time in an isothermal cavity followed by injection of after‐fire air. During the experiments, SO 2 reacted with the porous, thin‐walled CaO, CaCO 3 and MgO cenospheres, formed when CMA calcined, while NO x was reduced by hydrocarbon radicals from the organic acetate decomposition. While Ca was the dominant contributor to SO 2 reduction by CMA in the isothermal furnace zone, Mg also contributed to SO 2 reduction. At gas temperatures ≤ 950°C, Mg reacted directly with SO 2 in the isothermal furnace zone and was the dominant SO 2 remover in the post‐furnace quenching zone while indirectly SO 2 at higher isothermal zone temperatures by precluding pore‐mouth plugging when CaSO 4 formed. Interactions among hydrocarbons, SO 2 , and NO x are important but not fully understood.