Study on the phase transformation mechanism and influencing factors of inorganic condensable particulate matter from coal-fired power plants.

In this study, the concentration of inorganic ions (SO 4 ²⁻, NH 4 ⁺, NO 3 ⁻ and NO 2 ⁻) and morphological characteristics of condensable particulate matter (CPM) were investigated to elucidate the formation mechanism of inorganic CPM from ultra-low emission coal-fired power plants. The concentration of inorganic ions increased with the increase of H 2 O content and concentration of inorganic gaseous contaminants (SO 2 , NO X and NH 3), and decrease of condensation temperature, indicating the enhancement of heterogenous reaction in the saturated flue gas. Furthermore, NO X and SO 2 could undergo redox reactions, leading to an elevation in the concentration of SO 4 ²⁻ and NO 3 ⁻. Additionally, the introduction of NH 3 resulted in increased concentrations of SO 4 ²⁻, NO 3 ⁻, and NO 2 ⁻, highlighting the significant role of NH 3 neutralization in CPM nucleation. The condensation of SO 3 /sulfuric acid aerosols was enhanced under saturation conditions, and SO 2 and SO 3 /sulfuric acid aerosols could contribute synergistically to the formation of SO 4 ²⁻. Moreover, morphological analysis revealed the presence of both well-aggregated solid CPM and dispersed liquid CPM, confirming the formation of inorganic CPM during fast condensation. Furthermore, the detected CPM were composed of S and O, which identified the significant role of sulfates in the inorganic CPM. These findings provide valuable insights for the control of inorganic CPM in flue gas systems. [Display omitted] • Condensation temperature and humidity exhibited a significant impact on the formation of inorganic CPM. • The evolution of SO 4 ²⁻, NO 3 ⁻, NO 2 ⁻, and NH 4 ⁺ in a complex multi-complex flue gas environment was studied. • Morphological analysis substantiated the particles condensation and agglomeration during rapid condensation. [ABSTRACT FROM AUTHOR]