Thermodynamic and economic performance of oxy-combustion power plants integrating chemical looping air separation

Oxygen supply from cryogenic air separation unit (ASU) causes high economic cost and energy penalty, which hinders the practicability of oxy-combustion technology. Chemical looping air separation (CLAS) as a thermodynamic-efficient and cost-effective approach can satisfy the oxygen demands for oxy-combustion power plants. To optimize process configuration and identify the effect of recycling position for oxy-combustion power plants integrating CLAS (i.e. OXY-CLAS), the paper focuses on process simulation, thermodynamic analysis and techno-economic evaluation of two typical OXY-CLAS systems. For sastifying the oxygen concentration demand in oxy-combustion, the mixture of recycled flue gas and steam is adopted as the reduction medium in CLAS. For OXY-CCLAS (using cold recycled flue gas as oxygen releasing medium in CLAS), its net efficiency and exergy efficiency are 4.80 and 4.54% points higher than those of oxy-combustion coupled with cryogenic ASU, respectively. Meanwhile, its cost of electricity is reduced about 12.18% whilst its CO2 avoidance cost and CO2 capture cost decrease about 48.14% and 39.34%, respectively. When compared between two OXY-CLAS systems, OXY-WCLAS (utilizing warm recycled flue gas in CLAS) exhibits better performance both on thermodynamic and economic aspects. The exergy efficiency of WCLAS system is 1.29% points higher than that of CCLAS system. (C) 2020 Elsevier Ltd. All rights reserved.