PHASE-EQUILIBRIA IN THE SYSTEM WATER-METHYLDIETHANOLAMINE-PROPANE

Aqueous solutions of alkanolamines are commonly used to strip acid gases (CO2 and H2S) from hydrocarbon streams. Processes for stripping acid gases from gaseous streams are well understood; however, the application to liquids is not as advanced. Experimental data available are scarce for systems containing aqueous amine solutions and the constituents of liquefied petroleum gases. To this end, new data are presented for the equilibria in the system propane-water-methyldiethanolamine (MDEA). A knowledge of the phase behavior in this system is required to model the equilibria encountered in the more complex systems of industrial importance. This work is a comprehensive study of the phase equilibria in the system propane-3 M MDEA, including vapor-liquid, liquid-liquid, and vapor-liquid-liquid equilibria. Experimental measurements were made for temperatures between 0 and 150-degrees-C and pressures up to 20 MPa. The data were correlated using the Stryjek-Vera modification of the Peng-Robinson equation of state. In addition, a composition-dependent mixing rule was required to fit the data adequately.