LAUSR

Abstract Low-temperature fouling becomes severer as the selective catalyst reduction (SCR) system is widely applied in the power plant. In this study, the effect of two additives on the fouling of the heat exchanger in the coal-fired power plant (such as air preheater, economizer) has been investigated. The growth curves, heat flux, and effective thermal conductivity are obtained. Both additives have a significant effect on inhibiting the low-temperature fouling. With an increasing flow rate of the additive, the inhibitory effect on the low-temperature fouling becomes more significant, and the sodium carbonate (SC) shows a better inhibitory effect on the low-temperature fouling. The effective thermal conductivities of the low-temperature fouling are 0.357 W/m/K, 0.275 W/m/K, 0.235 W/m/K, 0.215 W/m/K, 0.340 W/m/K, 0.285 W/m/K, and 0.232 W/m/K for Initial, SC1, SC2, SC3, SBC1, SBC2, and SBC3, respectively. To clarify the reduction mechanism of low-temperature fouling, the SEM-EDX analysis is conducted. The results show that the decreasing ammonium bisulfate (ABS) concentration in the low-temperature fouling with increasing injection quantity of additive can result in a loose microstructure which leads to a lower effective thermal conductivity. The present study help to understand the reduction mechanism of low-temperature fouling in air preheaters and economizers.