Jostein Gabrielsen1, Hallvard F. Svendsen2, Michael L. Michelsen1, Erling H. Stenby1, and Georgios M. Kontogeorgis1. (1) IVC-SEP, Department of Chemical Engineering, Technical University of Denmark, Building 229, Lyngby, 2800, Denmark, (2) Department of Chemical Engineering, Norwegian University of Science and Technology, NTNU, Sem Sælandsvei 4, Trondheim, 7491, Norway
Using aqueous solutions of alkanolamines for CO2 capture from process streams is an established concept which has achieved wide industrial practice but usually for applications on a much smaller scale than power plant flue gas cleaning. The largest problems concerning the use of alkanolamines as absorbents for CO2 from power plant flue gases are the amount of energy needed to regenerate the CO2 rich solvent and the size of the CO2 capture plant. The focus of our work is to contribute to the modeling and simulation of both the absorption and desorption of CO2 in aqueous alkanolamines in order to develop reliable tools for the design and optimization of the process. Among the key parameters in the design process are the thermodynamics associated with the phase equilibria of systems containing CO2-water-alkanolamines, the kinetics of the chemical reactions involved and the mass transfer in the system. A simple thermodynamic model that is valid under the conditions encountered in flue gas cleaning has been developed and utilized with a steady-state mass transfer based absorption column model. The model has been validated using data obtained from a fully computerized pilot plant. The plant consists of a 4.36 meter absorber and a 4.1 meter desorber, capable of removing about 20 kg CO2 per hour. The experimental data have been gathered in a time frame of two weeks continuous operation.