Pilot-scale investigation and simulation-based optimization of MDEA/PZ for post-combustion CO2 capture

N-methyldiethanolamine (MDEA) is extensively applied in CO2 capture processes owing to its low energy consumption and high capacity, with its absorption performance significantly enhanced when blended with piperazine (PZ). To lower the energy consumption of post-combustion capture processes (PCC), this study integrates pilot-scale experiments with process simulation to investigate energy-saving optimizations. Using an aqueous solution of piperazine-activated MDEA (35% MDEA, 3.5% PZ, and 61.5% H2O by mass) as the absorbent, investigating the CO2 removal efficiency and regeneration energy consumption under different L/G ratios on a pilot-scale plant. Based on this, a process model was established using HYSYS software, and an improved decarbonization process, termed “semi-lean solution reflux + lean solution waste heat utilization + mechanical vapor recompression (SLR + WHU + MVR)," was proposed. Response Surface Methodology (RSM) was utilized to investigate the influence of semi-lean solution flow rate, lean solution flow rate, semi-lean solution split ratio, and vapor pressure on the regeneration energy consumption of the modified process. RSM optimization yielded optimal parameters: semi-lean solution flow rate of 0.0012 m3/h, lean solution flow rate of 0.004 m3/h, semi-lean solution reflux ratio of 0.13, and vapor pressure of 728.117 kPa. The regeneration energy consumption of the improved process under these parameters was 5.545 MJ/kg, which is a 10.3% reduction compared to the base model.