Simulation and Performance Assessment of Post Combustion Carbon Capture based on Chemical Absorption at Commercial Scale

The most dominant energy source is fossil fuels, such as coal-fired and combined-cycle gas turbine (CCGT) power plants. However, it has a significant negative impact on the environment due to the massive amount of CO2 emissions released from these sources. To combat this issue, researchers identified the most mature technology known as carbon capture, utilisation, and storage (CCUS). The solvent-based post-combustion CO2 capture process (PCC) is the most commonly used among other approaches. This approach is deployed using solvents such as monoethanolamine (MEA), which is the most widely used viable solvent in chemical absorption. However, this solvent has a negative impact on energy consumption. Thereby, the researchers investigated other solvents such as single solvents (e.g., piperazine (PZ) and 2-amino-2-methyl1-propanol (AMP)). Also, mixed solvents such as a blend of PZ and AMP. In this study, a steady-state rate-based PCC process model was developed using MEA, PZ, and mixed solvents (PZ with AMP). At the pilot scale, the three models were validated against experimental data using Aspen Plus®. The results of the model validation confirmed that the rate-based model for the three solvents predicted the experimental data with a lower than 10% deviation. When scaled up to a 250 MWe combined-cycle gas turbine power plant (CCGT), the packed column size for MEA solvent has the highest diameter and height, followed by PZ solvent and mixed solvents. Sensitivity analysis and technical evaluation were performed to obtain the optimal CO2 lean loading, which affects the liquid to gas ratio (L/G ratio) and specific re-boiler duty. Based on the L/G ratio, the values were 1.49 kg/kg, 0.76 kg/kg, and 1.55 kg/kg for MEA, PZ, and mixed solvents (PZ with AMP), respectively. On the other hand, specific re-boiler duties were 4.14 GJ/tonne CO2, 3.92 GJ/tonne CO2, and 2.95 kg/kg for MEA, PZ, and mixed solvents (PZ with AMP). Furthermore, economic evaluations were assessed for the three models at different solvents. The economic findings show that the lowest total annualised cost per tonne CO2 was estimated in the case of 40 %wt. PZ, which equals 21£ per tonne CO2. Control structure and design dynamics demonstrate that the performance of PZ was faster in terms of reaching the steady-state when compared to other solvents.