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Modeling Urea Processes: A New Thermodynamic Model and Software Integration Paradigm
(Special Shared Content with Virtual Materials Group)

High Pressure Data Regression 

Binary interaction parameters were determined for the following binary pairs based on published experimental data as described in Table 1.

Table 1: Binaries and Ranges for Urea Modeling

Typical results for ammonia/water, urea/water, and urea/ammonia are presented in Figures 3, 4, and 5.

Figure 3: Ammonia Water Vapor-Liquid Equilibrium at 80 °C

Figure 4: Urea/Water Bubble Pressures

Figure 5: Urea/Ammonia Bubble Pressures

The interaction parameters for the binaries defining the partial pressures of carbon dioxide and ammonia at high pressures were determined based on data published by Lemkowitz and co-workers (14, 15, and 16). The results show an actually better performance than the previous ionic model as shown in the isotherms at 150, 180 and 200° C. The experimental points for each isotherm were determined by constructing Clapeyron plots for each isoconcentrations published by Lemkowitz and then determining the bubble pressure for each isotherm.

Figure 6: Reactive Isotherm at 150 °C. Red line is molecular model, open squares UREA++ 2.0 using ionic model

Figure 7: Reactive Isotherm at 180 °C. Red line is molecular model, open squares UREA++ 2.0 using ionic model

Figure 8: Reactive Isotherm at 200 °C. Red line is molecular model, open squares UREA++ 2.0 using ionic model

Low and Medium Pressure Equilibrium