Techno-economic assessment of a commercial natural gas combined cycle with a chemical absorption plant using lean vapor compression modification

The primary challenge in integrating post-combustion CO₂ capture (PCC) with natural gas combined cycle (NGCC) is the significant energy consumption and capital costs. The novelty of this paper lies in proposing for the first time an advanced novel configuration that combines lean vapor compression (LVC) for the PCC plant with the NGCC plant incorporating exhaust gas recirculation (EGR) and selective exhaust gas recirculation (SEGR). The simulation results illustrated that implementing 33 % EGR can increase the CO₂ level in exhaust gas from a baseline of 4.2 to 6.3 mol%. In comparison, 53 % SEGR increased the CO₂ concentration in the flue gas to 8.8 mol%. Among the different configurations examined, SEGR + LVC achieved the highest energy saving for reboiler duty, which was 14 % compared to the baseline. In contrast, the EGR + LVC recorded the highest enhancement in thermal efficiency by 0.7 % points compared to the reference case. The LVC alone resulted in approximately 0.4 % points improvement in thermal efficiency for all configurations evaluated when the gas turbine loads were reduced from 100 to 60 %. This indicates that LVC is effective under partial loads. Finally, SEGR + LVC results in the greatest cost reduction for the PCC plant equipment, lowering the cost by 26 % compared to the baseline. However, the SEGR has the highest total plant cost and total overnight cost due to additional costs for the CO₂ membrane separation system.