Integration of process and solvent design towards a novel generation of CO2 absorption capture systems

A method for the integrated process and solvent design of absorption separation systems is proposed in this work. The method is employed here to improve the energetic performance of a pre-combustion CO2 absorption capture process by simultaneous optimization of process and solvent variables. In the proposed design method, the discrete nature of solvent molecules is relaxed avoiding the introduction of integer variables in the solution of the optimization problem. For this purpose, a molecular-based thermodynamic model, the perturbed-chain polar (PCPSAFT) equation of state, is used to establish a direct relationship between the process performance and the molecular characteristics of a hypothetical target solvent. Real solvent candidates are selected in a subsequent stage of molecular mapping by assessing substances from a data-base, using a Taylor approximation of the objective function. The simultaneous design method is shown to yield major improvements of the performance of CO2 absorption processes.