Analysis of ammonium bisulfate/sulfate generation and deposition characteristics as the by-product of SCR in coal-fired flue gas.

[Display omitted] • The generation characteristics of ABS/AS under non-catalytic conditions were investigated. • SO 3 and NH 3 enhanced ABS/AS generation and deposition. • The initial deposition temperature of ABS/AS is exponentially correlated with the product of SO 3 and NH 3 concentration. • Liquid ABS deposited firstly, the mixture of H 2 O, ABS and H 2 SO 4 or AS and (NH 4) 3 H(SO 4) 2 deposited at low temperature. The generation and deposition of ammonium bisulfate (ABS) in flue gas caused serious blockage and corrosion to the air preheater, which seriously affect the safe and economic operation of coal-fired power plants. The generation and deposition of ABS/ammonium sulfate (AS) under non-catalytic conditions were studied on a simulated air preheater test bench, and FT-IR and XRD tests were performed to characterize the products under different conditions. Experimental results show that the generation of ABS/AS is complicated and controlled by the concentration of SO 3 and NH 3 , the ratio of SO 3 to NH 3 (SO 3 /NH 3) and deposition temperature. Under the same SO 3 conditions, ABS/AS generation rate under different SO 3 /NH 3 conditions is 1:2 > 2:1 > 1:1. The initial deposition temperature of ABS/AS will increase with the corresponding increase of SO 3 and NH 3 concentration, and is exponentially correlated with the product of SO 3 and NH 3 concentration in flue gas. In the temperature range 390–223 °C, ABS generated and deposited under all conditions, and in the temperature range 223–131 °C, the mixture of H 2 O, H 2 SO 4 , and ABS generated and deposited when SO 3 /NH 3 is 2:1, and AS with a small amount of (NH 4) 3 H(SO 4) 2 generated and deposited when SO 3 /NH 3 is 1:1 and 1:2. [ABSTRACT FROM AUTHOR]