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EXPERIMENTAL STUDY OF THE VAPOUR-LIQUID EQUILIBRIA OF HI-I 2-H 2O TERNARY MIXTURES
A good agreement between Prophy calculations and experimental results is observed for HI and
H 2 O. I 2 concentration is underestimated.
• For 12% iodine content, corresponding to the top of the column, three HI concentrations, 19.5,
16.1 and 13.8% were studied (see Figure 8).
A good agreement between Prophy calculations and experimental results is observed for HI and
H 2 O. I 2 concentration is underestimated, and H 2 formation is observed for high HI concentration.
• For 4% iodine content, at low HI concentration, a good agreement for H 2 O and HI is observed.
• At HI high concentration, Hi concentration decreases versus time due to hydrogen formation.
Conclusions
The experimental study presented in this paper provides new data on liquid-vapour equilibrium of
HI-I 2 -H 2 O mixtures at high temperature and pressure (Doizi, 2009; Larousse, 2009). These results are
important to improve the modelling of the distillation column used in the SI cycle.
Optical online diagnostics have been used to determine the concentrations in the vapour phase.
The results show that, for global compositions close to the azeotrope, the thermodynamic model
correctly predicts concentrations of HI and H 2 O up to temperatures of about 260°C, while improvements
must be made to better represent the iodine concentration in the vapour phase.
For compositions with HI concentrations higher than the azeotropic one, it was pointed out that
the model cannot converge on finite solutions for temperatures higher than 150°C. Moreover, HI
dissociation into hydrogen and iodine has to be accounted for in high-HI and low-I 2 compositions.
Table 1: Concentrations studied in the low-pressure device
Compounds introduced Total P [H 2 O] & [HI) [I 2 ]
The analysis of the pertinence of the number of significant figures
is undergoing evaluation
I 2 = 3.98% - HI = 13.43% - H 2O = 82.58% X X X
I 2 = 4.04% - HI = 10.06% - H 2O = 85.90% X X X
I 2 = 3.95% - HI = 15.63% - H 2O = 80.42% X X
I 2 = 4.02% - HI = 18.91% - H 2 O = 77.08% X X X
I 2 = 12.09% - HI = 15.19% - H 2 O = 72.72% X X X
I 2 = 12.28% - HI = 15.5% - H 2 O = 72.22% X X X
I 2 = 12.11% - HI = 13.82% - H 2 O = 74.07% X X X
I 2 = 12.49% - HI = 17.85% - H 2 O = 69.66% X X X
I 2 = 12.45% - HI = 20.16% - H 2 O = 67.40% X X
I 2 = 11.94% - HI = 11.25% - H 2 O = 76.82% X X X
I 2 = 39.11% - HI = 9.57% - H 2O = 51.32% X X
I 2 = 38.61% - HI = 9.65% - H 2O = 51.74% X X X
I 2 = 38.75% - HI = 11.02% - H 2O = 50.24% X X
I 2 = 39.74% - HI = 11.67% - H 2O = 48.58% X X X
I 2 = 39% - HI = 13.11% - H 2O = 47.90% X X X
I 2 = 39% - HI = 13.56% - H 2O = 47.45% X X X
I 2 = 38.83% - HI = 13.59% - H 2 O = 47.58% X X
I 2 = 38.96% - HI = 13.625% - H 2O = 47.41% X X
I 2 = 49.18% - HI = 9.11% - H 2O = 41.71% X X X
I 2 = 63.95% - HI = 6.94% - H 2 O = 29.11% X X X
I 2 = 62.11% - HI = 7.9% - H 2 O = 29.99% X X X
I 2 = 64.97% - HI = 7.79% - H 2 O = 27.25% X X X
I 2 = 64.25% - HI = 7.95% - H 2 O = 27.81% X X X
I 2 = 85.37% - HI = 2.99% - H 2 O = 11.64% X X X
I 2 = 85.01% - HI = 3.45% - H 2 O = 11.54% X X X
I 2 = 84.5% - HI = 3.44% - H 2O = 12.06% X X X
I 2 = 84.66% - HI = 3.27% - H 2 O = 12.07% X X X
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