Formation and characteristics of condensable particulate matter from combustion of Zhundong high-sodium coal

• CPM concentrations from two Zhundong high-sodium coal combustion are 33.55 and 32.08 mg/Nm 3 . • Na + is the dominant metal cations in the inorganic fraction of CPM. • Na + concentration in CPM increases with the increasing Na content in three types of coal. • A high gas flow rate promotes Na + and Cl − concentrations in CPM. • Concentrations of Na + and Cl − in CPM are not significantly influenced between 1200 °C and 1400 °C. Condensable particulate matter (CPM) generated from coal combustion is a significant source of atmospheric fine particulate pollution. Zhundong coal is rich in reserves and high-quality power coal, which is widely used in coal-fired power plants. In this study, we investigated the formation and characteristics of CPM during the combustion of Zhundong high-sodium coal, and the effects of combustion conditions, including gas flow rate and combustion temperature on CPM. The results showed that the concentrations of CPM generated from the combustion of two Zhundong high-sodium coals were 33.55 and 32.08 mg/Nm 3 , and the concentrations of organic and inorganic fractions were 25.37, 23.96 mg/Nm 3 , and 8.17, 8.11 mg/Nm 3 , respectively. The organic fractions accounted for about 75.6 and 74.7 % of total CPM, and the main components of the inorganic fractions were Na + , Cl − , and SO 4 2− . Compared with the low-sodium coal (0.55 mg/Nm 3 ), a high concentration of Na + (0.90 and 0.84 mg/Nm 3 ) was generated in the inorganic fraction of CPM, which was more than 60 % of the total metal cations in the inorganic fraction of CPM. Meanwhile, the concentration of Na + in CPM increased with the increasing sodium content in three types of coal. Besides, when the gas flow rate increased from 3 L/min to 5 L/min, excess air coefficient (EAC) increased from 1.33 to 2.45, and the total concentration of CPM increased from 23.96 mg/Nm 3 to 32.08 mg/Nm 3 , which was similar to the concentrations of inorganic and organic fractions. Notably, the concentrations of Na + and Cl − increased significantly. As the combustion temperature of Zhundong coal increased from 1200 °C to 1400 °C, the concentration of CPM decreased from 35.04 mg/Nm 3 to 32.08 mg/Nm 3 . The concentration of inorganic fractions was not significantly influenced, especially Na + and Cl − , while the concentration of organic fractions decreased. Moreover, a high combustion temperature intensified SO 2 generation in flue gas, leading to an increase in the concentration of SO 4 2− in the inorganic fraction of CPM.