Investigation on PM formation from combustion of lignite with high contents of AAEMs (alkali and alkaline earth metals) and Fe: Effect of the reaction temperature

Coal-fired power plants require higher flexibility and a broader range of the operating temperature than before to accommodate the load regulation of the power grid. The relationship between the reaction temperature and the characteristics of particulate matter (PM) need to be better understood. In this study, Zhundong coal combustion was conducted in a drop tube furnace at different reaction temperatures in air. The PM characteristics and elemental contributions are investigated in detail. The experimental results show that the mass yields of PM_0.4 and PM_0.4-10 are non-monotonic with the reaction temperature. The competition between the generation of inorganic fumes and the removal of inorganic fumes by Si–Al-bearing minerals governs the mass yield of PM_0.4. At higher reaction temperature, generation of Ca, Mg, Fe-containing fumes increases, contributing most to the increment of PM_0.4; while the sulfation of chlorides is inhibited, resulting in more Cl in PM_0.4. The S content in PM_0.4 is mainly affected by the sulfation of AAEMs (alkali and alkaline earth metals) oxides. The mass yield of PM_0.4-10 is controlled by the competition between the fragmentation of char or mineral particles and the coalescence of mineral particles. For Zhundong coal combustion, the reaction temperature is recommended to be 1273K–1373K to control PM emission.