Formation of solids in ammonia-based CO₂ capture processes - Identification of criticalities through thermodynamic analysis of the CO₂-NH₃-H₂O system

The formation of solid intermediate compounds may lead to equipment clogging and plant shutdown in ammonia-based CO₂ capture processes. In this work, the thermodynamics of the CO₂-NH₃-H₂O system are analyzed with a focus on solid formation. The critical streams and unit operations that may be concerned with solid formation are identified based on an exemplary process simulation and on ranges of operating conditions typically reached according to the literature. Implications for process design and energy consumption are discussed and ternary phase diagrams mapping the composition regimes of solid formation and the typical operating conditions are presented.