Dynamic modelling, validation and analysis of post-combustion chemical absorption CO₂ capture plant

Development of dynamic models for post-combustion CO₂ capture using monoethanolamine solvent has been reported in the literature. Such models are only validated at steady-state, which means the models can predict process performance at different operating points. However, without dynamic validation, there is no guarantee that the model in question would predict dynamic responses accurately. This paper presents a dynamic validation study. The absorber and regenerator were modelled to account for mass transfer with chemical reactions assumed at equilibrium. Plant data logs were provided by the University of Texas at Austin. Three cases were considered: a conventional process and two cases with intercooled absorbers. The absorber temperature profile, capture level and reboiler duty were used for comparison. It is observed that the model satisfactorily predicts the pilot plant behaviour under multiple process inputs and disturbances. The validated model was then used to analyse the effect of increasing inlet flue gas moisture content and the impact of effective intercooling on the process performance. The former marginally influences the capture level, but significantly affects temperature profile, hence is an important parameter in model validation. The latter enhances capture level, and provides evidence that CO₂ absorption is mass transfer limited.