Reduction of combustion-generated SO(sub 2)-NO(sub x) by fine mists of CMA

摘要

Effectiveness of the chemical calcium magnesium acetate (CMA) as a dual SO(sub 2)-NO(sub x) reduction agent was recently demonstrated. Water-soluble CMA can either be sprayed (aqueous) or injected dry in high-temperature post-flame regions of furnaces. Organic volatiles, released during pyrolysis of CMA, react to reduce NO(sub x). The simultaneous formation of highly porous calcium oxide cenospheres greatly facilitates heterogeneous reactions with S0(sub 2). Reductions of both SO(sub 2) and NO(sub x) on the order of 90% have obtained at a Ca/S molar ratio of 2, 2-3% O(sub 2) concentrations, 4-5 s residence times, and gas temperatures between 750-950 C, with dry-injected ground CMA, (particle size on the order of 50 (mu)m). In the present experiments, fine mists of aqueous CMA, were introduced in the high temperature (850-1050 C) environment of a furnace. SO(sub 2) reductions on the order of 90% were recorded at a Ca/S molar ratio of 1, or about half of the amount used for the dry-injection experiments. NO(sub x) reduction was just over 20%, similar to the NO(sub x) reduction achieved with dry injection experiments at a Ca/S molar ratio of 1. At a Ca/S ratio of 2, wet injection removed virtually all of the SO(sub 2); however, a NO(sub x) reduction of only 30% was attained which was much lower than the 80 to 90% reduction achieved with dry injection under similar conditions. The total alkali metal utilization for CMA was estimated to be 25%. Calcium utilization of 65% were determined with wet injection experiments conducted with Ca formate, acetate, and propionate.