Steady state simulation and exergy analysis of supercritical coal-fired power plant with CO2 capture

Abstract

Integrating a power plant with CO2 capture incurs serious efficiency and energy penalty due to use of energy for solvent regeneration in the capture process. Reducing the exergy destruction and losses associated with the power plant systems can improve the rational efficiency of the system and thereby reducing energy penalties. This paper presents steady state simulation and exergy analysis of supercritical coal-fired power plant (SCPP) integrated with post-combustion CO2 capture (PCC). The simulation was validated by comparing the results with a greenfield design case study based on a 550MWe SCPP unit. The analyses show that the once-through boiler exhibits the highest exergy destruction but also has a limited influence on fuel-saving potentials of the system. The turbine subsystems show lower exergy destruction compared to the boiler subsystem but more significance in fuel-saving potentials of the system. Four cases of the integrated SCPP-CO2 capture configuration was considered for reducing thermodynamic irreversibilities in the system by reducing the driving forces responsible for the CO2 capture process: conventional process, absorber intercooling (AIC), split-flow (SF), and a combination of absorber intercooling and split-flow (AIC+SF). The AIC+SF configuration shows the most significant reduction in exergy destruction when compared to the SCPP system with conventional CO2 capture. This study shows that improvement in turbine performance design and the driving forces responsible for CO2 capture (without compromising cost) can help improve the rational efficiency of the integrated system.