Choi SB  Mock CS  Yang W  Ryu CK  Choi SC

Vol. 25,  No. 3, pp. 245-255, Sep.  2019
10.7464/ksct.2019.25.3.245

SO2 NOx Flue gas condenser Oxyfuel combustion Pollutant

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Pressurized oxy-fuel combustion is a promising technology for CO2 capture with a benefit of improving power plant efficiency compared with atmospheric oxy-fuel combustion. Prior to CO2 compression in this process, a flue gas condenser (FGC) is used to remove H2O while recovering the latent heat. At the same time, the FGC has a potential for high-efficiency removal of SOx and NOx by exploiting their good solubility in water. In this study, experiments were carried out in a lab-scale, direct contact FGC under different pressures varying between 1 and 20 bar to evaluate the removal efficiency of SO2 and NOx for individual gases and their mixture. In the tests for individual gases, 20% and 76% of NOx was removed at 1 bar and 10 bar, respectively. Even higher removal efficiencies were achieved for SO2, and also these were maintained for longer as the pressure increased. In the tests for SO2 and NOx mixture, the removal efficiency of NOx increased from 13% at 1 bar to 56% at 20 bar because of higher solubility at elevated pressures. SO2 in the mixture was initially dissolved almost completely and then increased by 1,219 ppm at 1 bar and by 165 ppm at 20 bar. Overall, the removal efficiency of SO2 and NOx was increased at elevated pressures, but it was lower in the mixture compared with individual gases at identical conditions because of a lower pH and associated chemical reactions in water.