(462d) A Modeling Methodology for Predicting Intensified CO2 removal Efficiency with Rotating Packed Bed

The opportunity in process intensification (PI) of carbon dioxide (CO₂) capture has drawn much attention recently. Since last decade, rotating packed bed (RPB) has been considered as an intensified alternative to conventional packed bed (PB) in CO₂ chemical absorption processes which require excessive absorber volume resulting from mass transfer resistance across vapor-liquid interface during the absorption process [1-3].

Reliable predictions of intensified CO₂ removal efficiency in RPB are essential to design the intensified CO₂ absorption/stripping process. In this study, we present a modeling methodology with sound theoretical basis for predicting the CO₂ removal efficiency in RPB. The methodology assumes the modeling of RPB and that of PB are identical if the gravitational force presented in RPB can be properly taken into account in modeling the mass transfer resistance. The methodology consists of three steps. First, we validate the PB model with PB experimental data [4]. The PB model is based on Aspen rate-based PB model with liquid film discretization (Aspen RateSep) [5]. Second, we predict the CO₂ removal efficiency of RPB experiments [1,4] with the validated PB model. Through this step, we identify the difference in CO₂ removal efficiency with and without the gravitational effect. Third, we account for the gravitational effect in RPB with the adjustable mass transfer factors in the validated PB model. Specifically, the liquid mass transfer coefficient factor and the interfacial area factor are chosen to account for the RPB gravitational effects with the validated PB model. The absolute average deviation (AAD) between the prediction results and the experimental RPB data [1,4] are found to be less than 10% when lean loading of MEA is in the typical operating range of 0.16 ~ 0.44 mol CO₂/mol amine, suggesting a robust predictive capability of our modeling methodology.

This modeling methodology not only provides new insights on RPB, but also avails chemical engineers a practical and theoretically sound modeling capability to estimate the intensified CO₂removal efficiency when replacing PB with RPB. Furthermore, by taking advantages of proven modeling tools in commercial simulators, the methodology could be widely practiced by engineers worldwide to examine the process intensification potential of replacing PB with RPB.

[1] Yu, C.H., Chen, M.T., Chen, H., Tan, C.S., “Effects of Process Configurations for Combination of Rotating Packed Bed and Packed Bed on CO₂ Capture”, Applied Energy, 175, 269-276 (2016).

[2] Yu, C.H., Lin, Y.X., Tan, C.S., “Effects of Inorganic Salts on Absorption of CO₂ and O₂ for Absorbents Containing Diethylenetriamine and Piperazine”, Int. J. Greenh. Gas Cont., 30, 118-124 (2014).

[3] Yu, C.H., Cheng, H.H., Tan, C.S., “CO₂ Capture by Alkanolamine Solutions Containing Diethylenetriamine and Piperazine in a Rotating Packed Bed”, Int. J. Greenh. Gas Cont., 9, 136-147 (2012).

[4] Thiels, M., Wong, D.S.H., Yu, C.H., Kang, J.L., Jang, S.S., Tan, C.S. Modeling and Design of Carbon Dioxide Absorption in Rotating Packed Bed. 11^th IFAC Symposium on Dynamics and Control of Process Systems.895-900 (2016).

[5] Zhang, Y., Chen, H., Chen, C.C., Plaza, J.M., Dugas, R., Rochelle, G.T. Rate-Based Process Modeling Study of CO₂ Capture with Aqueous Monoethanolamine Solution. Ind. Eng. Chem. Res.48, 9233-9246 (2009).

Keywords: Process Intensification; Rotating Packed Bed; Aspen Plus; CO₂ Chemical Absorption; Mass Transfer Coefficient; Interfacial Area