Transformation and removal of ammonium sulfate aerosols and ammonia slip from selective catalytic reduction in wet flue gas desulfurization system |
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Authors: | Teng Cheng Xincheng Zhou Linjun Yang Hao Wu Hongmei Fan |
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Affiliation: | Key Laboratory for Energy Thermal Conversion and Control, Ministry of Education, Southeast University, Nanjing 210096, China;Jiangsu Frontier Electric Technology Co., Ltd., Nanjing 211102, China;School of Energy and Mechanical Engineering, Nanjing Normal University, Nanjing 210042, China |
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Abstract: | Selective catalytic reduction (SCR) denitration may increase the emission of NH4+ and NH3. 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 NH4+ 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 NH4+ in the desulfurization slurry is quite low, a high level of NH4+ was still contained in the fine particles at the outlet of the scrubber. When the accumulated NH4+ in the desulfurization slurry was high enough, the WFGD system promoted the conversion of NH3 to NH4+ and increased the additional emission of primary NH4+ aerosols. With the decline of the liquid/gas ratio and flue gas temperature, the removal efficiency of ammonia sulfate aerosols increased, and the NH4+ 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 NH4+ concentration and pH values of the slurry. |
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Keywords: | Corresponding authors. Selective catalytic reduction (SCR) Wet flue gas desulfurization (WFGD) Ammonium sulfate Ammonia slip Emission characteristics |
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