Kinetics of solid formation in the chilled ammonia system and implications for a 2nd generation process

The Chilled Ammonia Process is a mature post-combustion CO₂ capture process. The formation of solids in the process at high CO₂ and NH3 concentrations was already described in the original patent, but is relatively poorly understood and difficult to explore experimentally. Thermodynamic properties that complicate the experimental investigation, such as the high vapor pressures of CO₂ and NH3 and the resulting incongruent solubility as well as the fast decomposition of the solids, are discussed in this work. Preliminary results for the metastable zone width and for nucleation kinetics in the ammonium bicarbonate/water system are presented. The solubility of ammonium bicarbonate derived from dissolution experiments is close to the historical literature values and an explanation for the slight deviation is discussed.