Process analysis of intensified absorber for post-combustion CO₂ capture through modelling and simulation

Process intensification (PI) has the potential to significantly reduce capital and operating costs in post-combustion CO₂ capture using monoethanolamine (MEA) solvent for power plants. The intensified absorber using rotating packed bed (RPB) was modelled based on Aspen Plus^® rate-based model, but some build-in correlations in Aspen Plus^® rate-based model were replaced with new correlations suitable for RPB. These correlations reflect centrifugal acceleration which is present in RPB. The new correlations were implemented in visual FORTRAN as sub-routines and were dynamically linked to Aspen Plus^® rate based model. The model for intensified absorber was validated using experimental data and showed good agreement. Process analysis carried out indicates: (a) CO₂ capture level increases with rotating speed. (b) Higher lean MEA inlet temperature leads to higher CO₂ capture level. (c) Increase in lean MEA concentration results in increase in CO₂ capture level. (d) Temperature bulge is not present in intensified absorber. Compared with conventional absorber using packed columns, the insights obtained from this study are (1) intensified absorber using RPB improves mass transfer significantly. (2) Higher flue gas temperature or lean MEA temperature will not be detrimental to the reactive separation as such cooling duty for flue gas can be saved. (3) Inter-cooling cost will not be incurred since there is no temperature bulge. A detail comparison between conventional absorber and intensified absorber using RPB was carried out and absorber volume reduction factor of 12 times was found. These insights can be useful for design and operation of intensified absorber for CO₂ capture.