Modelling of the reactive absorption of CO2 using mono-ethanolamine

The post-combustion capture of CO2 by reactive absorption using amines is a widely studied technology for the mitigation of CO2 emissions, especially from the fossil fuel-fired power plants. Reactive absorption of CO2 is a well-studied process on lab-scale. For the efficient design of reactive absorption columns, a reliable and predictive rate-based process model is necessary. In this work, a detailed rate-based model, which considers multicomponent mass transfer, chemical reactions in the film and in the bulk phase, non-ideal phase behaviour, fluid dynamics and heat transfer, is presented. The model is validated using the published pilot-scale experimental results of the absorption of CO2 by aqueous mono-ethanolamine (MEA), where two different types of structured packings (Sulzer BX and Sulzer Mellapak™ 250.Y) were employed. The model predicts the experimental profiles of the temperature and the concentration of CO2 in the liquid phase with an accuracy of ±8%. Furthermore, based on the Hatta numbers, the necessity of the liquid film discretisation is analysed for a given operation window. The paper also presents the results of a sensitivity analysis of the most relevant parameters on the overall CO2 absorption for two representative operating points (one for each packing). The inlet flow rate of the gas and liquid streams, the composition of CO2 and MEA in lean solvent, the distribution coefficient, the liquid hold-up and the effective interfacial area were the most sensitive parameters that affected the overall CO2 absorption. The sensitivity analysis is useful to understand the influence of the input parameters on the performance of the absorption column and for the optimisation of the reactive absorption of CO2 using amines.