Variation of nitrate and nitrite in condensable particulate matter from coal-fired power plants under the simulated rapid condensing conditions

Abstract

In this work, condensation temperature, H2O vapor, SO2, SO3 and NH3 were studied to explore the formation mechanism of nitrate ions (NO3−) and nitrite ions (NO2−) in condensable particulate matter (CPM) discharged by ultra-low emission coal-fired power plants. Some important results were obtained: (i) The concentration of NO3− and NO2− increased with the decrease of condensation temperature, and H2O vapor could also promote the formation of NO3− and NO2−. (ii) The effects of SO2 and SO3 varied at different saturated states of flue gas, which was caused by the redox reaction of SO2 and NOX or the formation of H2SO4. (iii) NH3 could promote the nucleation of NO3− and NO2−, and the promotion effect also existed in the existence of SO2 or SO3. It is worth mentioning that SO3 and SO2 might synergistically inhibit the formation of NO3− and NO2−, regardless of the presence of NH3. The research results would enrich peoples understanding of the chemical and physical characteristics of NO3− and NO2− in CPM and provide a basic reference for the control of CPM emitted from coal-fired power plants.