Optimum synthesis of solvent-based post-combustion CO₂ capture flowsheets through a generalized modeling framework

A generalized framework for the optimal design of post-combustion CO₂ capture processes based on a systemic and flexible equilibrium separation model that employs orthogonal collocation on finite elements techniques is proposed. Within this context, a column section of adaptive separation capability and functionality serves as the fundamental structural block for the identification of efficient separation schemes. Separation column sections in combination with heat transfer blocks, as well as stream splitters and mixers enable the generation and evaluation of alternative flowsheet configurations within a nonlinear optimization program. The main objectives for the flowsheet evaluation involve separation and thermal efficiency that eventually impact the economics of the overall process. Vapor–liquid equilibrium calculations are performed using statistical associating fluid theory for potentials of variable range (Mac Dowell et al., Ind Eng Chem Res 49:1883–1899, 2010). The proposed design framework is used for the optimal design of five alternative flowsheet configurations for the separation of CO₂ from a flue gas stream using a 30 % weight monoethanolamine aqueous solution. These flowsheets illustrate the various connection patterns between the process units and indicate suitable distribution of process-driving forces through which the overall efficiency can be drastically enhanced.