Energy performance analysis of post-combustion carbon capture using piperazine for large-scale natural gas combined cycle power plants

Post-combustion carbon capture (PCC) via chemical absorption has the potential to reduce CO2 emission significantly. The main challenges to this technology include the high energy consumption and high capital and operating costs. Alternative process configurations and new solvents are being pursued to reduce the energy consumption process. In this study, the rate-based model of the PCC process using piperazine (PZ) was developed in Aspen Plus® V8.4. The model was validated at pilot scale with experimental data. The model correctly predicted the CO2 capture level, rich loading and reboiler duty measured in the pilot plants. The validated model was scaled up to a PCC plant capable of processing flue gas from a 250 MWe natural gas combined cycle (NGCC) power plant. Three different configurations of the large-scale PCC process using 30-40 wt% PZ were simulated and the energy consumption was evaluated to determine which combination of configuration and solvent gives the best energy performance. The energy performance of the PCC process using PZ was also compared to the standard process using 30 wt% monoethanolamine (MEA) solvent. A regeneration energy of 4.97 GJ/tonneCO2 was obtained for the PCC process with 30 wt% MEA. Compared to the lowest regeneration energy obtained using the standard PCC process with PZ, the regeneration energy reduces by 35%, 41%, and 45% respectively for 30, 35 and 40 wt% PZ concentrations. The minimum regeneration energy of 2.41 GJ/tCO2 was achieved with the advanced flash stripper (AFS) process using 40 wt% PZ.