Exergy Analysis based on CO₂ Capture and Selective Exhaust Gas Recirculation in a Natural Gas Combined Cycle Power Plant

A novel integrated combined cycle with post-combustion carbon capture system is proposed to capture and recycle CO₂ through the integration of selective exhaust gas recirculation (S-EGR) for higher system operating efficiency. Based on the operating data of an actual combined cycle power plant, the study explores the impact of S-EGR integration on combined cycle and carbon capture system. Results show that: After S-EGR integration, the exergetic efficiencies of carbon capture and combined cycle are improved by 6.9% and 1.3%, respectively; The combustion chamber is the part with the largest Exergy destruction in the combined cycle, accounting for 44.8%, followed by the steam turbine, condenser and heat recovery steam generator (HRSG), the main reason for the Exergy destruction is the temperature difference; After post-combustion carbon capture system is integrated with the combined cycle, the thermal and exergetic efficiency both reach the peak when the S-EGR recycle rate (SRR) is 10%, and then gradually decrease.