Conventional and advanced exergy analysis of post-combustion CO2 capture based on chemical absorption integrated with supercritical coal-fired power plant

Abstract

Post-combustion CO2 capture (PCC) based on chemical absorption is one of the strategic technologies identified to reduce emission of greenhouse gases from various power plants. However, PCC based on chemical absorption incurs serious energy penalty due to the use of energy for solvent regeneration. Reducing the energy/exergy use in this process can reduce energy penalties. It is also important to increase the efficiency of the CO2 capture system. This study focuses on: steady state simulation of a closed-loop PCC plant integrated with supercritical coal-fired power plant (SCPP); conventional and advanced exergy analyses of the PCC; and case studies on strategies to reduce exergy destruction in the system components. The conventional exergy analysis evaluates the amount and location of exergy destruction within the whole system. The advanced exergetic analysis estimates the sources of the exergy destruction in individual component or the whole system and the potential for reducing it. The results show that the energy consumption and the efficiency of the PCC process can be improved by recovering the avoidable exergy destroyed in the system components. This is important because for every 1% reduction in the energy required for capture, costs can be lowered to between 0.7–1%.