Measurement of VLE

Physical and Chemical Equilibrium for Chemical Engineers, Second Edition. Noel de Nevers. 2012 John Wiley Sons, Inc. Published 2012 by John Wiley Sons, Inc. 

FIGURE 8.1 The mercaptan manufacturing facility at the Borger (Texas) facility of the Chevron Phillips Chemical Company. At least 10 distillation columns are visible. (Courtesy of the Chevron Phillips Chemical Company.) 

FIGURE 8.2 Schematic view of the simplest possible VLE measurement. 

If such data were available for all the possible mixtures of industrial interest, at the pressures of industrial interest, then we would not need the estimation and correlation procedures described in Sections 8.6 and 8.7 and Chapter 9. Although such tables are available for several thousand binary mixtures, they are rarely available for ternary and more complex mixtures. Most of the available tables of this kind are for atmospheric pressure many of the industrial applications are at pressures far from atmospheric. 

There are other ways of measuring VLE that are less direct but quicker and cheaper [5] their goal is the same as the methods described above, to produce the equivalent of Table 8.1 for the mixture of interest at the pressure of interest. 

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The measurement of VLE can be carried out in several ways. A common procedure is to use a recycle stiU which is designed to ensure equiHbrium between the phases. Samples are then taken and analy2ed by suitable methods. It is possible in some cases to extract equiHbrium data from chromatographic procedures. Discussions of experimental methods are available (5,11). Eor the more challenging measurements, eg, conditions where one or more components in the mixture can decompose or polymeri2e, commercial laboratories can be used. 

Kato, R. and Gmehling, J., Systems with ionic liquids measurements of VLE and data and prediction of their thermodynamic behavior using original UNIFAC, mod. UNIFAC(Do) and COSMO-RS(Ol), /. Chem. Thermodyn., 37, 603, 2005. 

ABB1 Abbott, M.M. Low pressure phase equilibria measurement of VLE. Fluid Phase Equilib. 29 (1986) 193-207. 

Paul, H.-L Krug, J. Knapp, H. Measurement of VLE, hE and vE for binary mixtures of n-alkanes with n-alkylbenzenes Thermochim. Acta 1986,108, 9-27... 

Guilbot, R Fiseher, K. Valtz, A. Theveneau, P. Baba-Ahmed, A. Richon, D. Measurement of VLE (TPx or TPxy data) for hydrogen sulfide + (dimethylsulflde or ethylmethylsulfide or carbon disulfide) and methane solubilities in (dimethylsulflde or ethylmethylsulfide or methylmercaptan or ethylmercaptan). Fluid Phase Equilib. 2007, 260, 49-59. 

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