Gas Turbine Combined Cycle System Integration With Exhaust Gas Recirculation for Boosted Power and Improved Carbon Capture Operations

Abstract The objective of this paper is to demonstrate the added value of exhaust gas recirculation (EGR) in improving and enabling the integration of a post-combustion carbon capture plant with the natural gas combined cycle (NGCC). The EGR technique involves recirculating a fraction of the flue gas from the stack back into the gas turbine inlet, where it is mixed with ambient air. The data shows that EGR increases the concentration of CO2 in exhaust gas while decreasing the amount of flue gas sent to the carbon capture plant (CCP). This dual effect enables the reduction of both CCP’s total energy consumption and capital expenditures. The study also investigated the EGR impact on NGCC performance at base load and part load operation. NGCC performance has been evaluated utilizing GE Vernova’s (GEV) internal mass and heat balance tools. CCP performance and cost were assessed using commercial tools ProMax and Aspen Process Economic Analyzer. The study found that NGCC with CCP with a 30% EGR ratio increases net output by around 1.7% and net efficiency by about 0.6% when compared to the non-EGR scenario. Furthermore, EGR improves NGCC part load efficiency (PLE). The NGCC efficiency increases by around 0.6% at an ambient temperature of 15°C with 30% EGR and at 50% NGCC part load. Moreover, the paper showed that EGR primarily reduces the size of the flue gas cleaning and absorption system, which accounts for the majority of equipment expenses. The study estimated a 7% reduction in overall CCP costs at 30% EGR.