Distillation mole fractions profile

FIG. 13-53 Liquid-phase mole fraction profiles for ethanol-benzene-water distillation, (a) Low-purity profile, b) Intermediate-purity profile, (c) High-purity profile. 

FIG. 13-109a Resp onses after a 30 percent increase in the feed flow rate for the mnlticomponent-dynamic-distillation example of Fig. 13-100. Profiles of liquid mole fractions at several times. 

Fig. 9.12 a) Configuration of reactive distillation column for hydration of ethylene oxide to ethylene glycol used by Ciric and Miao (1994). b) Equilibrium model calculations for the ethylene glycol process showing column profiles for liquid phase mole fraction, temperature and vapor phase molar flow, c) Nonequilibrium model calculations for the ethylene glycol process for a column of diameter 1.7 m showing the corresponding column profiles. Details of the simulations are available in Baur et al. 

The compositions in the column are much more complex. To study these, we will first look at two computer simulations for the distillation of benzene, toluene, and cumene in a column with 20 equilibrium contacts. The total flow and temperature profiles for this simulation are given in Figures 5-2 and 5-3. respectively. With a specified 99% recovery of benzene in the distillate, the liquid mole fractions are shown in Figure 5-4. 

In a first approach, the use of the external function in GAMS is compared to an Aspen Plus simulation based on the same thermodynamic data. In this simulation for a reactive distillation with fixed stage numbers and feed stages, the acetic acid dimerization is neglected and a simple reaction kinetic model based on the liquid mole fractions is applied for comparison purposes. The results show exactly the same condenser and reboiler heat duties for both calculations. The perfect agreement between these two calculations which is also confirmed by the concentration profiles clearly demonstrates that the use of the external functions in GAMS gives as thermodynamically accurate results as Aspen Plus. 

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