Modelling analysis of solid precipitation in an ammonia-based CO2 capture process

Aqueous ammonia is a promising absorbent for CO2 capture. However, the high volatility of ammonia raises operating problems in aqueous ammonia-based post-combustion CO2 capture process. In pilot-plant trials at Australia's Munmorah Power Station, solids precipitated in the overhead condenser and the reflux lines of the stripper, shutting down the entire pilot plant. In this study, we adopted a rigorous rate-based model developed in our previous work to investigate how operating conditions, such as ammonia concentration in the solvent, stripper pressure and condenser temperature, affect precipitation of the solid. We then applied a rich split configuration to the solvent regeneration process, optimising both the split ratio and feeding position, with the aim of eliminating the precipitation. Based on this study, applying a rich split configuration to the conventional regeneration process will significantly reduce both solid accumulation rate and the energy requirement for CO2 regeneration.