Effects of flue gas recirculation on energy, exergy, environment, and economics in oxy‐coal circulating fluidized‐bed power plants with CO2 capture. (17th November 2020) - Kim, Semie
Summary: CO2 capture and storage(CCS) are required for coal‐fired power plants, which are major sources of anthropogenic CO2 emission. In this study, energy, exergy, environment, and economic (4E) analyses were performed for a 500‐MWe oxy‐coal ultra‐supercritical circulating fluidized‐bed (CFB) power plant with CO2 capture. The effect of the location of flue‐gas recirculation (FGR) on the 4E values was investigated for wet FGR (wFGR) at 170°C, dry FGR (dFGR) at 68°C, and 80% wet and 20% dry FGR (wdFGR). The net electricity efficiencies of the wFGR and dFGR power plants were 37% and 36%, respectively. The exergy loss was the largest in the combustor and boiler area, where process improvement was possible. The levelized cost of electricity was approximately 60 $/MWh. The return on investment was 6.7% and 6.1%/y for the wFGR and dFGR plants, respectively. The CO2 emission rate decreased by 90% (from 690 to 76 kg‐CO2 /MWh) in the oxy‐coal power plants with CO2 capture. Relative to the wFGR, the dFGR was advantageous for preventing material corrosion because of the lower sulfur content in the FGR stream. For the wdFGR power plant, the process performance was intermediate, that is, between that of the wFGR plant and that of the dFGR plant. The study provided an effective tool for identifying the technological and economic effects of the FGR location for the oxy‐coal power plant with CCS via 4E analyses. Abstract : Electricity efficiency (37%) of a 500MWe oxy‐coal CFB power plant with wet flue gas recirculation (FGR) was higher than that (36%) of dry FGR. Exergy efficiency was calculated 35% in the wet FGR and 34% in the dry FGR. Sulfur of dry FGR was less accumulated in recycle streams than that of wet FGR. The LCOE (61 $/MWh) of dry FGR was higher than that (60 $/MWh) of wet FGR.