Modeling Study on Absorption of CO2 by Aqueous Solutions of N-Methyldiethanolamine in Rotating Packed Bed

The work presents a theoretical investigation of the absorption of CO 2 by aqueous solutions of N -methyldiethanolamine (MDEA) in a rotating packed bed (RPB). The diffusion-reaction process for CO 2 -MDEA mass transfer in RPB is modeled according to Higbie’s penetration theory with the assumption that all reactions are reversible. A three-dimensional distribution of carbon dioxide concentration varying with the time and penetration depth in liquid film and an average mass transfer rate at interface are obtained. The intensification within the RPB is mainly achieved by the sharper concentration profile of the dissolvable gas in liquid film; the short lifetime of liquid film resulting from frequent renewal of the film on packing surface significantly increases the mass transfer coefficient. Experiments were carried out at various rotating speeds, liquid flow rates, and temperatures in RPB. The validity of this model is demonstrated by the fact that most of the predicted y out (mole fraction of CO 2 in outlet gas) agree well with the experimental data with a deviation within 4%. Besides, this study makes a quantitative comparison between dynamic- and static-state mass transfer coefficients for this reactive absorption and a discussion on their applicability.