Rate-Based Modeling of CO2 Absorption in Aqueous NH3 in a Packed Column

Abstract

A rigorous rate-based model for the aqueous ammonia (NH3) based CO2 absorption in a packed column has been used to simulate the recently available results from pilot plant trialing of aqueous NH3 based post combustion process (PCC) at the Munmorah power station, New South Wales, Australia. The model is based on RateSep module, a rate- based absorption & stripping unit operation model in Aspen Plus®, and uses an improved thermodynamic model for NH3-CO2-H2O system to predict the performance of CO2 capture. The evaluation of the thermodynamic model via validation of vapor liquid equilibrium and heat of absorption of the NH3-CO2-H2O system shows that the model can satisfactorily predict experimental results from the published literatures. The predicted results from the rate-based model also agree reasonably well with pilot plant results including CO2 absorption rate and NH3 loss rate. The rate- based model is then utilized for the extended study of the effect of operation pressure, aqueous NH3 concentration and liquid inlet temperature on the CO2 absorption and NH3 loss. Two different absorber configurations split flow and inter-cooling have been investigated as possible options for control of the NH3 loss.