Energy-saving design for regeneration process in large-scale CO2 capture using aqueous ammonia

This work evaluated the energy consumption of a large-scale post-combustion carbon capture (PCC) process for a 500 MW coal-fired power plant using aqueous ammonia solution. Firstly, the rate-based model in Aspen Plus was used to simulate the benchmarked process reported in the literature. In the benchmarked process, the ammonia stripper for the water wash loop and the carbon dioxide stripper in the carbon dioxide capture loop were designed relatively independently. The regeneration energy was reported to be 8.47 GJ/ton-CO2 using the solvent with 0.23 CO2 lean loading in mol-CO2/mol-NH3. By optimizing the benchmarked process, the optimal lean loading is about 0.20 and the regeneration energy was reported to be 6.74 GJ/ton-CO2. By integrating the ammonia stripper and carbon dioxide stripper, it was found that there is a limit on the regenerated lean loading of CO2 (∼0.15) that allows the closing of mass balance; however, the regeneration energy could be reduced to 4.0 GJ/ton-CO2.