Rate-based modeling and economic optimization of next-generation amine-based carbon capture plants

Highlights: • A new, pseudo-transient re-formulation for rate-based column models. • Seamless integration with a library of pseudo-transient unit operation models. • Application to simulation and optimization of complex carbon capture processes. • Validation of next-generation flowsheet against a rigorous thermodynamic model. • Results reveal economic effect of solvent stability and flue gas composition. -- Abstract: Amine scrubbing processes remain an important technology for mitigating the contribution of carbon emissions to global warming and climate change. Like other chemical processes, they can benefit from computer-aided optimization at the design stage, but systematic optimization procedures are rarely employed due to the challenges of simulating the requisite rate-based mass transfer and reaction models. This paper presents a novel approach for the simulation and optimization of rate-based columns, with specific application to the absorber and stripper columns found in (amine-) solvent-based carbon capture processes. The approach is based on pseudo-transient continuation, and the resulting column models are easily incorporated into large-scale process flowsheets with other previously developed pseudo-transient models. We demonstrate that the proposed approach allows for gradient-based optimization of next-generation amine scrubbing processes by considering a complex carbon capture process under three different operating conditions. The results provide general insight into the design of amine scrubbing processes, and shadow prices at the optimal point(s) suggest potential avenues for improving the process economics. The effects of carbon dioxide removal percentage and flue gas composition on process economics are briefly analyzed.