Water residue curve

Fig. 5. The acetone—2-propanol—water system where I represents the 2-propanol—water azeotrope, (a) Residue curve map (34) (b) material balance lines...

Fig. 11. Separation of nitric acid, HNO, and water, H2O, using sulfuric acid, H2SO4, as the solvent, (a) Residue curve map and material balance lines where...

The vapor is thea withdrawa from the stiH as distillate. The changing Hquid composition is most coavenieafly described by foUowiag the trajectory (or residue curve) of the overall composition of all the coexistiag Hquid phases. An exteasive amouat of valuable experimental data for the water—acetoae—chloroform mixture, including biaary and ternary LLE, VLE, and VLLE data, and both simple distillation and batch distillation residue curves are available (93,101). Experimentally determined simple distillation residue curves have also been reported for the heterogeneous system water—formic acid—1,2-dichloroethane (102). 

Fig. 16. Residue curve map calculated for the ethanol—water—benzene mixture where A is the end poiat of the vapor line I represents a homogeneous...

Podebush Sequence forPthanol—Water Separation. When ethyl acetate is used as the entrainer to break the ethanol—water azeotrope the residue curve map is similar to the one shown in Figure 21d, ie, the ternary azeotrope is homogeneous. Otherwise the map is the same as for ethanol—water—benzene. In such... 

More Complex Mixtures. AH the sequences discussed are type I Hquid systems, ie, mixtures in which only one of the binary pairs shows Hquid—Hquid behavior. Many mixtures of commercial interest display Hquid—Hquid behavior in two of the binary pairs (type II systems), eg, secondary butyl alcohol—water—di-secondary butyl ether (SBA—water—DSBE), and water—formic acid—xylene (92). Sequences for these separations can be devised on the basis of residue curve maps. The SBA—water—DSBE separation is practiced by ARGO and is considered in detail in the Hterature (4,5,105,126). 

FIG. 13-58 (Continued) Residue curve maps, (h) MEK-MIPK-water system containing two minumum-hoiling binary azeotropes. 

FIG. 13-73 Residue curve maps for acetone-methanol systems, (a) With water, (h) With MIPK. 

The transformed variables describe the system composition with or without reaction and sum to unity as do Xi and yi. The condition for azeotropy becomes X, = Y,. Barbosa and Doherty have shown that phase and distillation diagrams constructed using the transformed composition coordinates have the same properties as phase and distillation region diagrams for nonreactive systems and similarly can be used to assist in design feasibility and operability studies [Chem Eng Sci, 43, 529, 1523, and 2377 (1988a,b,c)]. A residue curve map in transformed coordinates for the reactive system methanol-acetic acid-methyl acetate-water is shown in Fig. 13-76. Note that the nonreactive azeotrope between water and methyl acetate has disappeared, while the methyl acetate-methanol azeotrope remains intact. Only... 

FIG. 13-76 Residue curve map for the reactive system methanol-acetic acid-methyl acetate-water in chemical eqiiihhriiim. 

The water residue level is also determined from the relative responses of the analytes to the internal standards. The sample residue levels are calculated by comparison with an average response factor determined by triplicate analysis of a five-point calibration curve. Samples receive 5ng of each internal standard (0.1 ngmL ) and are concentrated 50-fold by Ci8 SPE before analysis to achieve adequate instrumental sensitivity. The calculations to determine the residue level in water are outlined in Section 7.3.3. 

Bottom Product B with a straight line joining the Distillate D and Entrainer Feed E, as shown in Figure 12.24. Pinch point curves for the middle section can now be constructed by drawing tangents to the residue curves from the difference point (net overhead product). This is shown in Figure 12.25 for the system ethanol-water-ethylene glycol. The area bounded by the pinch point curves defines the middle section operation leaf. 

Fig. 10.1 Effect of water on the residual current-potential curves at a platinum electrode in PC [10]. (a) Cathodic side in 0.1 M Bu4NCI04. Water concentration curve 1,...

Nitromethane shows the simplest residue curve map with one unstable curved separatrix dividing the triangle in two basic distillation regions. Methanol and acetonitrile give rise two binary azeotropic mixtures and three distillation regions that are bounded by two unstable curved separatrices. Water shows the most complicated residue curve maps, due to the presence of a ternary azeotrope and a miscibility gap with both the n-hexane and the ethyl acetate component. In all four cases, the heteroazeotrope (binary or ternary) has the lowest boiling temperature of the system. As it can be seen in Table 3, all entrainers except water provide the n-hexane-rich phase Zw as distillate product with a purity better than 0.91. Water is not a desirable entrainer because of the existence of ternary azeotrope whose n-hexane-rich phase has a water purity much lower (0.70). Considering in Table 3 the split... 

Figure 4.15 shows the calculated residue curves according to Eq. (51) at various temperatures in the still, while the temperature at the condenser was kept constant by evaporation of water due to natural convection. The azeotropic concentration of this mixture (xi = 62 mol%) in practical terms does not vary much with pressure and temperature. The arheotropic iso-propanol content at 50 °C is as low as 38 % and will not decrease much further at even lower still temperatures. The minimum arheotro-... 

Fig. 4.15. Residue curves for iso-propanol (l)-water (2) mixtures at various still temperatures, kn3/te3 = 0.5. Air is the third component (3).

Fig. 4.18. Experimental data for the residue curves of the mixture iso-propanol (1 )-water (2) according to Eq. (52) for low /VTU-values and various sweep gas inlet humidities Y2,m and moderate evaporation rates (Knq = 0.9999) [32].

Residue curve maps of the THF system were predicted for reactive distillation at different reaction conditions (Fig. 4.29). The topology of the map at nonreactive conditions (Da = 0) is structured by a binary azeotrope (unstable node) between water and THF. Pure water and pure THF are saddle nodes, while the 1,4-BD vertex is a stable node. 

At Da —> °° (Fig. 4.29(c)), only pure water and pure THF remain stable nodes. The residue curves first are dominated by the reaction stoichiometry and approach the chemical equilibrium surface, and then converge to the water vertex or to the THF vertex. When starting from pure 1,4-BD, the undesired byproduct of water will be the final product in the distillation still. 

Fig. 4.30. Residue curve maps for reactive membrane separation 1,4-BD — THF + Water p= 5 atm Knudsen-membrane. (a) Da = 0 (b)...

Fig. 22. Removal of residual water signal by HSVD. Curve a, FFT of original signal. The horizontal bar indicates the water region curve b, FFT of the signal after water components have been identified by HSVD fitting and subtracted. Reproduced with permission from de Beer and van Ormondt, in NMR Basic Principles and Progress, Vol. 26 (eds Diehl et at.), p. 202, Springer-Verlag, Berlin, 1992.

Figure 3.9 Sketch of a residue curve map isopropanol, n-propanol, water.

Figure 8.4 presents the residue curve map of simultaneous phase and chemical equilibrium at normal pressure. Special coordinates, Xx (acid + water) and X2 (acid + ester) enable tbe representation of all four components in a bidimensional... 

Figu re 8.4 Residue curve map of the reactive mixture lauric acid/2-ethylhexanol/water/2-ethylhexyl dodecanoate a = initial estimation b = experimental data [2],... 

In the following, the strategy presented before will this time be applied for developing a process for the esterification of lauric acid with methanol. All the thermodynamic data for pure components and binary mixtures are available in Aspen Plus. A residue curve map of the reactive mixture at equilibrium can be computed as described in Appendix A. A useful representation can be done in reduced coordinates defined by Xx = water + add and X2 = add + ester. The diagram displayed... 

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