Performance of simultaneous desulfurization and denitration using limestone modified by wood vinegar in O₂/CO₂ coal combustion

The performance of simultaneous desulfurization and denitration during coal combustion in O₂/CO₂ atmosphere with premixed and injected limestone modified by wood vinegar (LMWV) was investigated in a tube furnace and a drop tube furnace, respectively. The SO₂ and NO reduction efficiency are 91.0%~94.9% and 23.5%~30.8% respectively during the combustion of coal premixed with LMWV at 1 173 ~ 1 323 K at the Ca/S molar ratio of 2.0. The desulfurization and denitration rates increase with raising the Ca/S molar ratio, and the optimum Ca/S molar ratio is from 1.5 to 2.0. The higher the sulfur content of coal, the greater desulfurization and denitration rates are gained during coal combustion. The performance of desulfurization and denitration with LMWV is better than that with calcium acetate. The maximum desulfurization and denitration rates of 75.8% and 86.6% respectively are gained by injecting LMWV directly into the flue gas of O₂/CO₂ coal combustion at both 1 223 K and 1 323 K and the Ca/S molar ratio of 2.0 with a residence time of 0.8 s. When the ammonia is injected into the reactive zone at NH₃/NO molar ratio of 0.75, the desulfurization rates are 73.2% and 63.9%, and the denitration rates are 93.2% and 94.8%, respectively at the combustion temperature of 1 223 K and 1 323 K.