Vapour-liquid equilibrium data

Calculate the binary parameters for the UNIQUAC equation by using the vapour-liquid equilibrium data for benzene(l)-i-propyl alcohol (2) at 760 mmHg (Tassios, 1993). The following values for other UNIQUAC parameters are available from Tassios (1993) ri=3.19, qi=2.40, r2=2.78, q2=2.51. The data are given in Table 15.6. 

Given the temperature and pressure, the concentration of any component in the vapour phase can be obtained from the concentration in the liquid phase, from the vapour-liquid equilibrium data for the system. 

These compositions should be checked against the vapour-liquid equilibrium data for acetone-water and the values of the split-fraction coefficients adjusted, as necessary. 

Consider the accuracy of the equilibrium data required to calculate the number of equilibrium stages needed for the separation of a mixture of acetone and water by distillation (see Chapter 11, Example 11.2). Several investigators have published vapour-liquid equilibrium data for this system Othmer et al. (1952), York and Holmes (1942), Kojima et al. (1968), Reinders and De Minjer (1947). 

At pressures above a few atmospheres, the deviations from ideal behaviour in the gas phase will be significant and must be taken into account in process design. The effect of pressure on the liquid-phase activity coefficientmustalso be considered. A discussion of the methods used to correlate and estimate vapour-liquid equilibrium data at high pressures is beyond the scope of this book. The reader should refer to the texts by Null (1970) or Prausnitz and Chueh (1968). 

Perry et al. (1997) give a useful summary of solubility data. Liquid-liquid equilibrium compositions can be predicted from vapour-liquid equilibrium data, but the predictions are seldom accurate enough for use in the design of liquid-liquid extraction processes. 

Hala, E., Wichterle, I. Polak, J. and Boublik, T. (1968) Vapour-liquid Equilibrium Data at Normal Pressure (Pergamon). 

A good understanding of methods used for correlating vapour-liquid equilibrium data... 

At low reflux ratios the calculated number of stages will be very dependent on the accuracy of the vapour-liquid equilibrium data available. If the data are suspect a higher than normal ratio should be selected to give more confidence in the design. 

Figure 11.39. Vapour-liquid equilibrium data for hydrocarbons...

The catalytic hydration of olefins can also be performed in a three-phase system solid catalyst, liquid water (with the alcohol formed dissolved in it) and gaseous olefin [258,279,280]. The olefin conversion is raised, in comparison with the vapour phase processes, by the increase in solubility of the product alcohol in the excess of water [258]. For these systems with liquid and vapour phases simultaneously present, the equilibrium composition of both phases can be estimated together with vapour-liquid equilibrium data [281]. For the three-phase systems, ion exchangers, especially, have proved to be very efficient catalysts [260,280]. With higher olefins (2-methylpropene), the reaction was also performed in a two-phase liquid system with an ion exchanger as catalyst [282]. It is evident that the kinetic characteristics differ according to the arrangement (phase conditions), i.e. whether the vapour system, liquid vapour system or two-phase liquid system is used. However, most kinetic and mechanistic studies of olefin hydration were carried out in vapour phase systems. 

At high pressures, especially approaching the critical pressure, the accuracy of the vapour-liquid equilibrium data are questionable. Direct measurement is not easy prediction with equations of state is risky [1],... 

J. Gmehling, U. Onken, Vapour-Liquid Equilibrium Data Collection, DECHEMA Chemistry Data Series, vol. 1, 12 parts, DECHEMA, Frankfurt am Main, 1982. 

Liberatore, R., et al. (2008), Experimental Vapour-liquid Equilibrium Data of HI-H20-I2 Mixtures for Hydrogen Production by Sulphur-Iodine Thermochemical Cycle , Int. J. Hydrogen Energy, 33,4283-4290. 

The number of plates (defining the column configuration), feed, feed composition, column holdup, etc. for the problem are given in Table 4.9 (Chapter 4). The vapour-liquid equilibrium data and the kinetic data are taken from Simandl and Svrcek (1991) and Bogacki et al. (1989) respectively and are shown in Table 4.10 (Chapter 4). The vapour and liquid enthalpies are calculated using the data from Reid et al. (1977). As mentioned in Chapter 4, these data do not account for detailed VLE calculations and for any azeotropes formed. 

Gmehhng, J., Onken, U., Weidlich, U. (1982) Vapour-Liquid Equilibrium Data Collection, Vol. 1. Part 2s, 227. 

A good understanding of methods used for correlating vapour-liquid equilibrium data is essential to the understanding of distillation and other equilibrium-staged processes this subject was covered in Chapter 8. 

Thermodynamic consistency tests are well known, and have been frequently used for vapour-liquid equilibrium data in binary mixtures (for reviews one can see Gmehling and Onken, 1977 Acree, 1984 Prausnitz et al., 1986). These tests are based on theGibbs-Duhem equation and allow one to grade the experimental data for vapor-liquid equilibrium in binary mixtures. A more difficult problem is the consistency of data regarding vapor-liquid equilibrium in ternary or multicomponent mixtures. However, several thermodynamic consistency tests, also based on the Gibbs-Duhem equation, were suggested for vapor-liquid equilibrium in ternary or multicomponent mixtures (Li and Lu, 1959 McDermott and Ellis, 1965). 

Gmehling J., Onken U., Arlt W, Vapour-Liquid Equilibrium Data Collection, Frankfort, Dechema 1977 (Vol. D-1996... 

Wohlfarth, C., Vapour-Liquid Equilibrium Data of Binary Polymer Solutions Physical Science Data, 44, Elsevier, Amsterdam, 1994. 

Hala, E., I. Wichterle, J. Polak, and T. Boublik, Vapour-Liquid Equilibrium Data at Normal Pressures, Pergammon Press, Oxford, 1968. 

One hundred kilogram-moles per hour of a 30mole% bubble-point mixture of acetone (1) in water (2) is to be distilled at 1 atm to obtain 90mole% acetone and 95 mole% water using a column with a partial reboiler and a total condenser. The van Laar constants at this pressure are (E. Hale et al., Vapour-Liquid Equilibrium Data at Normal Pressures, Pergammon Press, Oxford, 1968) A12 = 2.095 and Aj, = 1.419. 

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