Energy penalty mitigation through exhaust gas recirculation: A technical evaluation of post-combustion carbon capture integrated with CCGT plants

Abstract

Integration of post-combustion carbon capture (PCC) units, using chemical solvent with combined cycle gas turbine (CCGT) power plants offers a promising strategy for mitigating the escalating CO₂ emissions. Nevertheless, this technology does come at a cost. It penalizes the plant by reducing the net power and overall efficiency. This study investigates the techno-economic effect of EGR on the energy penalty caused by PCC in a natural gas-fired CCGT power plant simulated using Aspen Plus. The results indicate that the utilization of an optimized 0.33 EGR ratio significantly increases the molar concentration of CO₂ by 51%, from 5.44% to 8.22%, while concurrently reducing the oxygen concentration by 46.82%, from 10.56% to 5.61%. Additionally, EGR minimizes the reboiler heat load of PCC by 34.53% while limiting the net power output by less than 0.5%. Economic analysis reveals that the steam requirement of CO₂ capture decreases from $14.23/tonne CO₂ captured (without EGR) to $9.26/tonne CO₂ captured at an EGR of 0.33. Furthermore, this work also investigated the relationship between the concentration of CO₂ in the gas stream and subsequent solvent requirements in a PCC unit.