New technology for control of NOx, SO2 and HCl emissions from large scale combustion plant using calcium magnesium acetate

Calcium magnesium acetate (CMA) combines the essential properties for NOx control by reburning and in furnace acid gas capture by calcium in one reducing agent. The organic content behaves like a fuel in the reburn zone of a furnace and the Ca content calcines in the furnace principally to CaO for acid gas capture. The technique can be modified for advanced reburning by the addition of urea to the CMA solution so that the selective non-catalytic reduction (SNCR) agent enters the reburn zone at the point of CMA injection. The performance of this novel technique has been assessed for NOx, SO2 and HCl control at the pilot scale, in a combustor operating at 80 kW. Simultaneous reduction of all three pollutants was obtained and a synergy between SO2 and HCl capture was identified. Comparison of the performance of calcium magnesium acetate with a suite of five other carboxylic salts has been performed. NOx reduction has been correlated to volatile organic content and the decomposition rates of the carboxylic salts, as determined by thermogravimetric analysis.