Reduction of SO2 and N2O Emissions without Increasing NOx Emission from a Fluidized Bed Combustor by Using Fine Limestone Particles

A modification of in-situ SO2 removal was proposed to suppress the increase in NOx with limestone feed to a bubbling fluidized bed combustor (BFBC). A laboratory-scale BFBC was operated. Coarse coal was burnt in the dense bed and fine limestone particles were employed so that only sorbent particles were entrained to the freeboard, thus SO2 removal by the sorbent was separated from the combustion of coal. By separating SO2 removal from combustion, an increase in NOx due to contact between sorbent and volatile-N could be avoided. Also N2O reduction by SO2 removal was observed.