Heat requirement for regeneration of aqueous ammonia in post-combustion carbon dioxide capture

Abstract

The present work evaluates ammonia as a carbon dioxide (CO2) solvent for post-combustion carbon capture, focusing on the thermal performance of the ammonia regeneration process and the operating conditions for the aqueous ammonia process. The main parameters investigated were the CO2-loading of the lean solution (0.2–0.5) and the ammonia concentration (2–20%). An equilibrium-based electrolyte model was used in process simulation software to evaluate the performance of the ammonia regeneration. The heat requirement was approximately 2500kJ/kg CO2 captured. Running conditions in which the precipitation of solids occurred did not enhance the thermal performance. The main reaction pathway for the absorption of CO2 was identified as the formation of bicarbonate through the reaction of ammonia with CO2. The heat of reaction required to desorb CO2 of ammonia was similar to that required for monoethanolamine (MEA). However, significantly less water was evaporated during the regeneration process with ammonia, resulting in a lower heat requirement for regeneration.