Choi GG  Na GS  Shin JH  Keel SI  Lee JK  Heo PW  Yun JH

Vol. 24,  No. 3, pp. 212-220, Sep.  2018
10.7464/ksct.2018.24.3.212

Oxy-fuel combustion In-furnace desulfurization Selective non-catalytic reduction (SNCR) N2O generation NH3 slip SO3 generation

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Oxy-fuel combustion is considered as a promising greenhouse gas reduction technology in power plant. In this study, the behaviors of NO and SO2 were investigated under the condition that in-furnace deNOx and deSOx methods are applied in oxy-fuel circulating fluidized bed combustion condition. In addition, the generation trends of SO3, NH3 and N2O were observed. For the purpose, limestone and urea solution were directly injected into the circulating fluidized bed combustor. The in-furnace deSOx method using limestone could reduce the SO2 concentration in exhaust gas from ~403 to ~41 ppm. At the same experimental condition, the SO3 concentration in exhaust gas was also reduced from ~3.9 to ~1.4 ppm. This trend is mainly due to the reduction of SO2. The SO2 is the main source of the formation of SO3. The negative effect of CaCO3 in limestone, however, was also appeared that it promotes the NO generation. The NO concentration in exhaust gas reduced to ~26 - 34 ppm by appling selective non-catalytic reduction method using urea solution. The NH3 concentration in exhaust gas was appeared up to ~1.8 ppm during injection of urea solution. At the same time, the N2O generation also increased with increase of urea solution injection. It seems that the HNCO generated from pyrolysis of urea converted into N2O in combustion atmosphere. From the results in this study, the generation of other pollutants should be checked as the in-furnace deNOx and deSOx methods are applied.