SEPARATIONS Carbon Dioxide Absorption and Desorption in Aqueous Monoethanolamine Solutions in a Rotating Packed Bed Majeed S. Jassim,* ,² Gary Rochelle, ‡ Dag Eimer, § and Colin Ramshaw | Department of Chemical Engineering, UniVersity of Bahrain, P.O. Box 32038, Bahrain, Department of Chemical Engineering, The UniVersity of Texas at Austin, Austin, Texas 78712, Hydro Oil & Energy, Research Centre, Porsgrunn, Norway, and Process Intensification and InnoVation Center, School of Chemical Engineering and AdVanced Materials, UniVersity of Newcastle upon Tyne, Newcastle upon Tyne, NE1 7RU, United Kingdom The absorption and desorption of carbon dioxide in aqueous monoethanolamine (MEA) was measured in a rotating packed bed of size 398 mm outside diameter, 156 mm inside diameter, and axial depth 25 mm. The effect of lean amine temperature (20 and 40 °C), peripheral rotor gravity (31 and 87 g), and various MEA concentrations were investigated. Using MEA concentrations above 30 wt % achieved lower CO 2 penetration levels. This is particularly pronounced for the 100% MEA solution. Comparison with conventional columns showed the advantages of using rotating packed beds in terms of saving size and space and efficient operation. 1. Introduction Imperial Chemical Industries (ICI) patented the HIGEE (high gravity) or the rotating packed bed (RPB) concept in late 1970s. 1,2 The HIGEE is one of the process intensification (PI) technologies that promotes size and weight reduction, enhances inherent safety with lower inventories, improves energy con- sumption, lowers capital cost, and addresses environmental concerns. 3 This technology takes advantage of centrifugal fields as stimulants for process intensification. 4 The dynamic behavior of multiphase fluids is dictated by the interphase buoyancy factor ∆Fg. Therefore, increasing the centrifugal acceleration improves the slip velocity, which in turn improves the flooding charac- teristics and interfacial shear stress, and consequently boosts the mass transfer coefficient. CO 2 capture and sequestration is one approach for reducing the emissions that cause global climate change and the burden of the carbon tax levy. Absorption/stripping is considered the state-of-the-art technology for CO 2 removal. Aqueous alkano- lamine solution absorbs acid gas components from flue gas streams in a countercurrent operation. The alkanolamine is then regenerated in a reboiled stripper. An extensive literature for the reactive mass transfer system of CO 2 -MEA-H 2 O is available. 5-12 Chambers and Wall 13 designed a mild steel centrifugal absorber with intermeshing concentric rings and no packing to remove 10-15% CO 2 from air using pure monoethanolamine (MEA) solution. The corrosive nature of pure MEA caused deterioration of the rich solution, and their results were not expressed in terms of overall gas mass transfer coefficient (K G a) because it was claimed that Henry’s Law is not applicable for very short contact time in the centrifugal absorber. Bucklin et al. 14 investigated the application of a rotating packed bed in selective H 2 S removal with MDEA. The loading of acid gas in rich solution was unexpectedly high but there was 25% error in the dry chemical analysis and that influenced the calculations of mass balances. The capacity of the rotating packed bed was fully exploited as runs with higher circulation rates and packing thickness were not possible due to flooding of the rotor. Lin et al. 15 investigated the effects of operating parameters on the overall mass transfer coefficient (K G a) using low MEA con- centrations of 6.1 and 12.2 wt % in a rotating packed bed with stainless steel wire mesh packing, 0.96 porosity, and 803 m 2 / m 3 specific surface area. The MEA solvent achieved the highest K G a values in comparison to those for the sterically hindered amine 2-amino-2 methyl-1-proanol (AMP) and NaOH. A comprehensive review and appraisal of HIGEE technology has recently been published by Rao et al. 16 The objective of our work was to test the performance of a pilot-plant scale rotating packed bed in absorption and desorption of carbon dioxide using MEA solutions. The resistances to mass transfer in both modes were identified. The effect of rotor speed, lean amine temperature, and amine strength were investigated. * To whom correspondence should be addressed. Tel.: (+973) 17 876189. E-mail address: drmajeed@gmail.com. ² University of Bahrain. ‡ The University of Texas at Austin. § Hydro Oil & Energy. | University of Newcastle upon Tyne. Figure 1. Flowsheet of experimental facility. 2823 Ind. Eng. Chem. Res. 2007, 46, 2823-2833 10.1021/ie051104r CCC: $37.00 © 2007 American Chemical Society Published on Web 04/03/2007