Dynamic simulation and parametric sensitivity study in reactive CO2 capture systems – A solvent comparison study

Abstract The control of CO 2 emissions released in the atmosphere is an indisputable need in order to avoid environmental and health consequences, as well as to reach European and global targets for climate change confrontation. During the last decades, various methods have been proposed towards this direction. As fossil fuels remain dominant in the energy field, technologies focused on CO 2 capture have been developed, known as Carbon Capture Systems (CCS). During the last decade, CCS have managed to become cost-competitive in relation to other technologies. However, CCS need to receive strong policy support in order to develop solid and applicable business cases. This work studies reactive absorption, a post-combustion method to remove CO 2 from flue gases using aqueous chemical solutions that react with CO 2 and capture it. In specific, this paper focuses on two alkanolamines as absorbents, Monoethanolamine (MEA) and 2-amino-2-methyl-1-propanol (AMP). Following previous work, a dynamic model was developed in Matlab®, simulating transient behavior of a packed column for reactive absorption. The methodology followed to solve the set of partial differential equations describing the problem was the Finite Differences Method (FDM). Based on experimental data from a pilot plant various scenarios were tested in order to investigate the reaction of the system in different operational perturbations, such as flow disturbances, changes in temperature and in the solution’s molarity. These factors were studied parametrically and the outcome of these simulations was used to perform a Sensitivity Analysis (SA) in order to determine the important parameters influencing CO 2 absorption performance. The parametric analysis showed that the inlet gas flow rate was the most influential factor determining the CO 2 absorption level for both solvents. In following, the temperature of the liquid entering the column was also statistically important having strong impact on absorption. Surprisingly, the flow of the lean solvent wetting the column seems to have lower impact than the gas flow. Thus, increased solvent flow does not ensure respective enhancement of the CO 2 absorption. Molarity is also very important as the quantity of amine in the solution determines the quantity of the captured CO 2 . In terms of reaction time towards disturbances, changes in liquid molar flow, liquid temperature and molarity seem to lead to higher reaction time until the system reaches a new steady state value (2–5 min). Finally, the results showed that there is a maximum capture level, beyond which the absorption cannot be further enhanced for specific conditions.