Transformation and removal of ammonium sulfate aerosols and ammonia slip from selective catalytic reduction in wet flue gas desulfurization system.

Author(s) Cheng, T.; Zhou, X.; Yang, L.; Wu, H.; Fan, H.
Journal J Environ Sci (China)
Date Published 2020 Feb

Selective catalytic reduction (SCR) denitration may increase the emission of NH and NH. The removal and transformation characteristics of ammonium sulfate aerosols and ammonia slip during the wet flue gas desulfurization (WFGD) process, as well as the effect of desulfurization parameters, were investigated in an experimental system equipped with a simulated SCR flue gas generation system and a limestone-based WFGD system. The results indicate that the ammonium sulfate aerosols and ammonia slip in the flue gas from SCR can be partly removed by slurry scrubbing, while the entrainment and evaporation of desulfurization slurry with accumulated NH will generate new ammonium-containing particles and gaseous ammonia. The ammonium-containing particles formed by desulfurization are not only derived from the entrainment of slurry droplets, but also from the re-condensation of gaseous ammonia generated by slurry evaporation. Therefore, even if the concentration of NH in the desulfurization slurry is quite low, a high level of NH was still contained in the fine particles at the outlet of the scrubber. When the accumulated NH in the desulfurization slurry was high enough, the WFGD system promoted the conversion of NH to NH and increased the additional emission of primary NH aerosols. With the decline of the liquid/gas ratio and flue gas temperature, the removal efficiency of ammonia sulfate aerosols increased, and the NH emitted from entrainment and evaporation of the desulfurization slurry decreased. In addition, the volatile ammonia concentration after the WFGD system was reduced with the decrease of the NH concentration and pH values of the slurry.

DOI 10.1016/j.jes.2019.08.002
Keywords Aerosols; Air Pollutants; Air Pollution; Ammonia; Ammonium Sulfate; Catalysis; Gases; Power Plants
ISSN 1001-0742
Citation J Environ Sci (China). 2020;88:7280.

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