Modeling of CO2-MEA-water using the extended electrolyte UNIQUAC equation

Lupong Kaewsichan, D. of Chemical Eng., F. of Eng., PSU.
Victor F. Yesavage, D. of Chemical and Petroleum Refining Eng., Colorado School of Mines, Golden, Colorado, USA.
Sami M. Selim, D. of Chemical and Petroleum Refining Eng., Colorado School of Mines, Golden, Colorado, USA.
Corresponding e-mail : luepongk@lovemail.com

Presented : "Regional Symposium on Chemical Engineering 1999", Vol. 1 : A56-1, Nov. 22-29, 1999, B.P. Smila Beach Hotel, Songkhla, Thailand
Key words : electrolyte, UNIQUAC, monoethanolamine, acid gas, carbondioxide, VLE

A thermodynamic model was developed for representing vapor-liquid equilibria of the CO2-monoethanolamine (MEA)-water system. The model accounts for chemical equilibria in the liquid phase and physical equilibria between the liquid and vapor phases. Activity coefficients are repre-sented by the Electrolyte-UNIQUAC equation. In this equation, the water and monoethanolamine are treated as solvents. Contributions from long-range ion-ion interactions are represented by a Debye-Hckel formula suitable for mixed solvents. Contributions from short-range forces between all spe- cies are represented by the UNIQUAC equation. Adjustable parameters of the Electrolyte UNIQUAC equation, representing short-range binary interactions, were determined by data regression using bi-nary, and ternary system VLE data. Predicted CO2 equilibria are in good agreement with the reported experimental data for aqueous solutions of the acid gas in MEA in the temperature range 25 to 120^oC.

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