SIMPLIFIED MODEL FOR THE CORRELATION OF VAPOUR-LIQUID EQUILIBRIUM IN THE CO//2-NH//3-H//2O SYSTEM

Abstract

A new simplified VLE model of the CO//2-NH//3-H//2O system under conditions of the distillation and absorption steps of the recycle urea process is developed. For the gaseous phase the virial state equation is adopted and the component activity coefficients are approximated by a simple linear expression. The resulting equations for the equilibrium constants of the physical and chemical equilibria are fitted to experimental values (in the literature) within the temperature range of 307 to 414 K and within the pressure range of 2 to 40 bar. Tests of the model on the experimental data are presented as well as the comparisons with other published simplified VLE models of the system.