A practical method for calculating VLE of NH3-H2O-CO2-N2-H2 system under high pressure is proposed in this paper. On the basis of the NH3-H2O-CO2 system

the molecular thermodynamic principle is used for calculating liquid-phase equilibria. The hyperbolic tangent function for the activity coefficient of the NH3-H2O system developed by Prausnitz is used in establishingthe VLE calculation method ior the NH3-H2O-CO2 system over a wide concentration range(NH3 10-90%(wt.)). PHS equation of state is used to calculate the vapor phase fugacity coefficient in the NH3-H2O-CO2-N2-H2 system under high pressure. Scope oi application: Temperature 30-70℃ Pressure 5.00-11.87MPa Liquid NH3 concentration 10-90%(wt. ) Liquid CO2 concentration 0-15%(wt. ) NH3/CO2 mole ratio in liquid phase≥ 5 The calculated results of the proposed model are in good agreement with both our experimental data and those from literature sources.