Development of a rate-based model for CO2 absorption using aqueous NH3 in a packed column

• A rate-based model for CO 2 absorption in aqueous ammonia in a packed column was developed. • The model was validated with results obtained from pilot plant trials under real flue gas conditions. • The availability of the model allows detailed analysis of the capture process and will guide process improvement, optimisation and scale up. A rigorous rate-based model for CO 2 absorption using aqueous ammonia in a packed column has been developed and used to simulate results from a recent pilot plant trial of an aqueous ammonia-based post-combustion capture process at the Munmorah Power Station, New South Wales, Australia. The model is based on the RateSep module, a rate-based absorption and stripping unit operation model in Aspen Plus, and uses the available thermodynamic, kinetic and transport property models for the NH 3 –CO 2 –H 2 O system to predict the performance of CO 2 capture. The thermodynamic and transport property models satisfactorily predict experimental results from the published literature. The modelling results from the rate-based model also agree reasonably well with pilot plant results, including CO 2 absorption rate, NH 3 loss rate, temperature profiles and mass transfer coefficients in the absorber. To gain insights into absorption performance, we used the rate-based model to analyse the species concentration profile, temperature profile, mass transfer rate and coefficient in the gas and liquid bulk phase along the packing height.