Investigating CO2 Absorption in Rotating Packed Beds: Development, Validation, and Operational Analysis of a Rate-Based Model

Effective modelling of the Rotating Packed Bed (RPB) process is crucial for accurately simulating CO2 absorption in aqueous amine solutions. Existing models often incorporate simplifying assumptions and rarely capture the simultaneous variations of critical phenomena inside the RPB apparatus, such as gas phase CO2 mass flow rate, liquid and gas temperatures, and pressure drop. This work addresses these challenges by developing a rate-based, steady-state model designed for CO2 capture, using monoethanolamine (MEA) as the solvent. Unlike previous works, this model effectively captures all these critical phenomena simultaneously. The model employs a first principles approach and solves material and energy balance equations using the shooting method. Two-film theory is used to represent mass transfer in conjunction with up-to-date correlations. The predicted results exhibit excellent agreement with the experimental data for a 30 wt. % MEA solution when comparing rich loading, with a maximum deviation of 1.1 %. The analysis of previously overlooked phenomena in RPB-based CO2 absorption provides valuable insights regarding the variations of key parameters along the radius, such as the influence of pressure drop and temperature. The observed decrease in gas pressure and sharp drop near the inner radius demonstrate the significant impact of frictional losses. In contrast, the temperature profiles of the gas and liquid phase reveal the interplay between exothermic reactions and counter-current flow.