Modeling Thermodynamic Properties Of Alkanolamine Systems Using Equation Of State

A new associated square well chain-like fluid equation of state with variable range (ASWCF-VR EOS) was extended to calculate densities, vapor-liquid equilibria, thermo-enthalpies, gas solubilities, viscosities and surface tensions for alkanolamine systems in this paper.Model parameters of 18 kinds of alkanolamines were obtained by correlating saturated vapor pressures and liquid densities of the pure substances at different temperatures. The overall average deviations of saturated vapor pressures and liquid densities of alkanolamines are 0.94% and 0.88% respectively. The vaporization enthalpies of alkanolamines were predicted by using these molecular parameters and the minimum deviation of them is 1.45%. Coupling with a simple mixture rule, the EOS can be further used to calculate thermophysical properties of the mixtures containing alkanolamines such as vapor liquid equilibria, densities and excess enthalpies of binary alkanolamine systems. With a introduction of the binary interaction adjustable parameters, the overall average deviations of temperatures, pressures and vapor mole fractions of binary alkanolamine systems can decrease from 7.43 K,7.47 kPa, 0.0382 to 2.26 K,1.11 kPa,0.0116 respectively, and the overall average deviation of their densities can be reduced from 1.01% to 0.67%. That of their excess enthalpies is 22.35% for the correlated result. The EOS can satisfactorily predict vapor liquid equilibria and densities of ternary alkanolamine systems using these binary interaction adjustable parameters.The reaction between CO2 and alkanolamine was approximately viewed as a strong cross association. It was successful to correlate solubilities of CO2 in aqueous alkanolamine solutions based on the assumption. Coupling with the excess Gibbs free energy viscosity model and the surface tension model based on scaled particle theory, the viscosities and surface tensions of alkanolamine systems were successfully calculated in this paper, where the minimum correlated deviations of viscosities and surface tensions are 2.06% and 0.83% respectively.The research shows that the new EOS can calculate vapor-liquid equilibria and densities for alkanolamine systems accurately. However, because of the specialty of alkanolamine systems, the EOS can only accurately describe thermo-enthalpies, solubilities of CO2, viscosities and surface tensions for part of alkanolamine systems...