Shuai Wang,Chunliang Shang,Yimin Deng,Jan Baeyens,Tatiana V. Plisko,Alexandr V. Bildyukevich,Tejraj M Aminabhavi,Xinying Liu,Mahluli Moyo,Helei Liu
The mass transfer plays a decisive role in screening and evaluation of amine solvents as well as in designing and scale-up of CO 2 capture. The influence of different operating parameters on mass transfer processes in CO 2 capture by EAE-1DMA2P amine solution was thoroughly investigated using a small-scale packed column. The mass transfer mechanism of EAE-1DMA2P amine solution in the capture of CO 2 was discussed by determining both mass transfer control steps and the reaction region between CO 2 and amine solvent, which provided a theoretical guidance for subsequent development of new solvents for large-scale applications. In addition, based on the experimental observations of K G a v , a prediction model for K G a v of EAE-1DMA2P composite amine solution was established by comparing two empirical models viz., Kohl-Riesenfeld-Astarita and Sheng of which Kohl-Riesenfeld-Astarita model provided a better fitting of the experimental results. The commonly used amine solvents and EAE-1DMA2P composite solvents were further compared and analyzed in terms of packed column size design and solvent consumption. The required packed column volume using EAE-1DMA2P composite solvent was only 4.95 m 3 , while the EAE-1DMA2P composite solvent has the smallest solvent consumption among all the solvents, indicating that this solvent has a lower operating cost than the other solvents, suggesting better industrial application.
The physical solubility and mass transfer performance of CO 2 absorption into aqueous N,N-dimethylethanolamine (DMEA) solution were comprehensively studied in the present work. The physical solubility (Henry’s law constant ( He )) was measured using a stirred cell reactor for pure DMEA and aqueous DMEA at temperatures from 293.98 to 333.03 K. Then, the physical solubility of CO 2 was obtained based on the “N 2 O analogy” method. Furthermore, He was correlated successfully by using an empirical polynomial model with an average absolute relative deviation (AARD) of 4.23%. The mass transfer performance was studied in a laboratory scale structured packing absorption column at DMEA concentration of 1–4 kmol/m 3 , liquid feed temperature of 293.15–333.15 K, liquid flow rate of 3.90–11.7 m 3 /m 2 -hr, CO 2 partial pressure of 6–20 kPa, lean CO 2 loading of 0.050–0.300 mol/mol, over the inert gas flow rate range of 26.11–43.52 kmol/m 3 -hr. Based on the experimental values of He for CO 2 into aqueous DMEA solution, the effect of the gas concentration of A in gas-liquid equilibrium ( y A ∗ ) on gas phase volumetric overall mass transfer coefficient ( K G a v ) was considered in this study, but found to be an insignificant influence that can be ignored. Analogously, an attempt to correlate the mass transfer coefficient K G a v and outlet concentration of CO 2 ( y out ) using semiempirical models as function of the mentioned operational parameters was conducted. The predictive correlations for K G a v and y out of the DMEA-CO 2 -H 2 O system in structured packing column are K G a v = L 0.23 0.6144 a eq - a C / p C O 2 + 0.02327 and ln y out = l n y in - 0.77 PV G Ω L 0.23 0.6144 a eq - a C / p C O 2 + 0.02327 , with acceptable AARDs of 4.59% and 1.48%, respectively.
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