A techno-economic evaluation of post-combustion carbon capture using renewable ammonia with different process configurations

Abstract

Aqueous ammonia can be used as a solvent in post-combustion carbon capture (PCC) instead of commercial solvents, which are mainly fossil based (e.g. MEA, DEA). Besides the lower cost and regeneration energy, it can be derived from renewable hydrogen, thus coupling the production of hydrogen with hard-to-abate sectors. However, there are still significant technical obstacles to overcome in this process, for instance, solid precipitation at the stripper overhead and ammonia slipping. To investigate this further, this work considers an ammonia-based PCC unit to treat 350 t/h of flue gas from a gas-fired power plant, while the process performance indicators are the CO2 product flowrate, ammonium bicarbonate (AmBic) content in the rich solvent, reboiler duty, regeneration energy, capital, and operational expenditures. Moreover, three process configurations are proposed: (i) Rich Solvent Flashing (RSF), (ii) Lean Vapor Compression (LVC), and (iii) a novel PCC unit coupled with a crystallizer (CRY) to induce ammonium bicarbonate formation. The results showed that the CRY configuration has the lowest CO2 production rate but can produce AmBic, which is a byproduct with economic potential. The LVC configuration has the lowest regeneration energy consumption, while the RSF configuration has the lowest costs. This study demonstrates the potential of aqueous ammonia as a solvent for PCC and provides valuable insights into the performance of different process configurations.

Topics & Concepts