Efficiency and Flexibility Improvement of Amine-Based Post Combustion CO₂ Capturing System (CCS) in Full and Partial Loads

Optimal design and operation of the CO₂ captures system integrated with power plants are crucial to minimize process energy consumption and associated costs. In this paper, the conventional process of monoethanolamine (MEA)-based post-combustion CO₂ capturing system is modified to reduce the process energy consumption for flexible and efficient integration to fossil-fueled power plants. Considering a flue gas stream similar to coal-fired power plants, rigorous rate-based modeling of the MEA-based CO₂ capture system is performed in Aspen Plus using the electrolyte nonrandom two-liquid thermodynamic package (ENRTL-RK). Afterward, three main process modifications, including lean vapor compression, rich solvent preheating, and rich solvent splitting, are investigated in both full and partial load conditions to assess their impacts on the process efficiency and energy consumption. The results demonstrate that the lean vapor compression and the rich solvent preheating modifications significantly reduce the process energy consumption by 13.5% and 8.4%, respectively. However, the addition of extra equipment such as compressors, flash vessels, and heat exchangers increase the capital and operational costs of the capture plant. Also, rich solvent splitting, which requires minor modifications in process equipment, reduces the energy consumption by 5.4%. Moreover, it is observed that the operating conditions for CO₂ capture vary significantly between partial and full load conditions, and considerable reduction in energy consumption and improvement in process flexibility can be achieved at optimal process conditions.