Abstract: The solubility of NH_3 in water in multicomponent systems under high pressure is of extreme importance to the new integrated ammonia and urea process. This paper proposes a new method for calculating the vaporliquid equilibria for aqueous ammonia solutions under high pressure. Based on the experimental data of the binary system of NH_3-H_2O in the high concentration range, a model has been established for the activity coefficients of NH_3 and H_2O to describe the non-ideality of the liquid phase; and the modified SIRK equation of state for polar compounds has been used to describe the non-ideality of the vapor phase under high pressure. The reliability of this model has been examined in the light of the experimental data of the solubility of NH_3 in H_2O under high pressure in the systems of NH_3-H_2O-N_2, NH_3-H_2O-N_2-H_2-Ar-CH_4 and NH_2-H_2O-N_2-H_2, the last being from Guerreri et al. Both the accuracy of calculation and the concentration range for applicability of this model have been found to surpass those of Guerrerl’s model.

摘要： The solubility of NH_3 in water in multicomponent systems under high pressure is of extreme importance to the new integrated ammonia and urea process. This paper proposes a new method for calculating the vaporliquid equilibria for aqueous ammonia solutions under high pressure. Based on the experimental data of the binary system of NH_3-H_2O in the high concentration range, a model has been established for the activity coefficients of NH_3 and H_2O to describe the non-ideality of the liquid phase; and the modified SIRK equation of state for polar compounds has been used to describe the non-ideality of the vapor phase under high pressure. The reliability of this model has been examined in the light of the experimental data of the solubility of NH_3 in H_2O under high pressure in the systems of NH_3-H_2O-N_2, NH_3-H_2O-N_2-H_2-Ar-CH_4 and NH_2-H_2O-N_2-H_2, the last being from Guerreri et al. Both the accuracy of calculation and the concentration range for applicability of this model have been found to surpass those of Guerrerl’s model.