Integrated solvent and process design for the reactive separation of CO_2 from flue gas

摘要

A model-based platform for assessing alternative designs and solvent blends for reactive separation processes is presented and applied to the problem of chemisorption of CO_2 from flue gas with amine solvents. We combine state-of-the-art thermodynamics with rigorous process simulation techniques for this purpose. A rate-based model of chemisorption units for CO_2 capture is implemented in the gPROMS modelling environment, using the statistical associating fluid theory for potentials of variable range (SAFT-VR)1 to represent mixture thermodynamics. Important features of our model are that both the reaction and phase equilibria are incorporated in the thermodynamic model, and as a result, enhancement factors are not required in the process model. As reaction products are accounted for at the level of the thermodynamic model (from a physical perspective), the generation of reaction products or heat is considered implicitly in the mass and energy balances, further simplifying the model. We validate our model using published pilot plant data, and subsequently apply this approach to the treatment of a typical industrial scale flue gas stream and demonstrate how it can be used to optimise simultaneously solvent composition and process operating conditions.