Rate-Based Process Modeling Study of CO2 Capture with Aqueous Monoethanolamine Solution

Rate-based process modeling technology has matured and is increasingly gaining acceptance over traditional equilibrium-stage modeling approaches. [Taylor et al. Chem. Eng. Prog. 2003, 99, 28−39] Recently comprehensive pilot plant data for carbon dioxide (CO2) capture with aqueous monoethanolamine (MEA) solution have become available from the University of Texas at Austin. The pilot plant data cover key process variables including CO2 concentration in the gas stream, CO2 loading in lean MEA solution, liquid to gas ratio, and packing type. In this study, we model the pilot plant operation with Aspen RateSep, a second generation rate-based multistage separation unit operation model in Aspen Plus. After a brief review on rate-based modeling, thermodynamic and kinetic models for CO2 absorption with the MEA solution, and transport property models, we show excellent match of the rate-based model predictions against the comprehensive pilot plant data and we validate the superiority of the rate-based models over the traditional equilibrium-stage models. We further examine the impacts of key rate-based modeling options, i.e., film discretization options and flow model options. The rate-based model provides excellent predictive capability, and it should be very useful for design and scale-up of CO2 capture processes.