H

(726135,762135)

#052

(746135,761435,764135)

(721435,724135,742135)

#056

(174325,714325,741325)

(7246135,7261435,7264135, 7426135,7462135, 7621435, 7624135,7642135)

(7461325,7461352,7614325, 7614352,7641325,7641352)

(7246135,7261435,7264135, 7426135,7462135, 7621435, 7624135,7642135)

(7461325,7461352,7614325, 7614352,7641325,7641352)

(7461325,7614325,7641325, 4761325)

(7461325,7614325,7641325, 6174325,6714325,6741325)

#062

(7214356,7241356,7421356)

#064.

#065

#066

(1743562, 7143562,7413562)

(1743256,1743526,7143256, 7143526,7413256.7413526)

#069

#071

#072

(132567,135367, 135627 )

#074

#075

#076

(132547,135247,135427) (213567)

#(ÎJ7\

#078

#079y'
#080\
#081'

#082

(1325467,1325647,1352467, 1352647,1354267,1354627, 1356247.1356427)

(1432567,1435267,1435627 4132567,4135267.4135627)

#083

#085

#086

(6132547,6135247,6135427)

(6143257, 6143275, 6143527, 6413257,6413275,6413527)

#087v

(4613257,4613275, 4613527)

#087v

#088

(1432567, 1432576, 1432756, 1435267,1435276,1435627)

(1432567,1435267,1435627, 1435672)

#096

mi

#093

#098

#095

#100

(214735,241735,247135, 421735,427135)

(143725,143752, 147325, 147352.413725,413752. 417325,417352)

(461735,467135,614735. 641735,647135)

(135724,135742,137254, 137524,137542)

(135726,135762,137256, 137526, 13756)

#101

(2671435, 2674135, 6271435, 6274135)

(2671435, 2674135, 6271435, 6274135)

#105 /1

(2147356, 2417356. 2471356, 4217356,4271356)

#111

#107

(4613752,4613725,4617352, 4617325,4671325,4671352, 6143725.6143752,6147325, 6147352,6413725,6413752, 6417325,6417352,6471325, 6471352)

#113

(1325746,1325764,1352746. (1354726,1354762) (1356724,1356742)

1352764)

(1435726, 1435762, 1437256, 1437526, 1437562, 1473256, 1473526,1473562,4135726, 4135762,4137256,4137526, 4137562,4173256,4173526, 4173562)

(6135724, 6135742, 6137254, 6137524,6137542)

#114

#114

#115

(2467135,2476135,4267135, 4276135,4627135)

(1356724.1356742,1357462, 1357624,1357642)

(3461735,2467135, 2476135. 2614735.2641735,2647135. 4261735,4267135,4276135)

(3461735,2467135, 2476135. 2614735.2641735,2647135. 4261735,4267135,4276135)

(2467135,2476135,4267135, 4276135,4627135)

(1356724.1356742,1357462, 1357624,1357642)

#119

#119

(1354726, 1354762, 1357426. 1357462, 1357642)

(1356724, 1356742, 1357264. 1357624,1357642,1372564, 1375264,1375624,1375642)

(1356724, 1356742, 1357264. 1357624,1357642,1372564, 1375264,1375624,1375642)

(2467137,2647135,2671435. 2674135,6247135,6271435, 6274135)

(2647135. 2671435, 2674135, 6247135,6271435, 6274135, 6427135)

(1354726, 1354762, 1357426. 1357462, 1357642)

(1354726. 1354762,1357246, 1357426,1357462, 1372546. 1375246,1375426, 1375462)

(2467137,2647135,2671435. 2674135,6247135,6271435, 6274135)

(4267135,4627135,4672135, 6427135,6472135)

#123

(2647135. 2671435, 2674135, 6247135,6271435, 6274135, 6427135)

#123

(4621735,4627135,4672135, 6214735,6241735,6247135, 6421735,6427135,6472135)

#124

#124

(1325746,1325764, 1352746, 1352761,1357246,1357264, 1357426)

#125

(1354726. 1354762,1357246, 1357426,1357462, 1372546. 1375246,1375426, 1375462)

#125

(1325746, 1325764, 1352746, 1352764, 1357246,1357264, 1357624)

(4267135,4627135,4672135, 6427135,6472135)

(4621735,4627135,4672135, 6214735,6241735,6247135, 6421735,6427135,6472135)

(1325746,1325764, 1352746, 1352761,1357246,1357264, 1357426)

FIG. 13-59 (Continued ) Distillation region diagrams for ternary mixtures.

(1325746, 1325764, 1352746, 1352764, 1357246,1357264, 1357624)

the distillate can also be driven to low levels (high-product recovery), although achieving such an operation depends on having an adequate number of stages and reflux ratio.

The bow-tie region for Feed F2 is significantly different, with the upper edge along the water-MIPK (MEK-free) face of the triangle and the lower edge along the distillation boundary. From this feed it is not possible to achieve a high-purity MIPK specification while simultaneously obtaining high MIPK recovery. If the column is operated to get a high purity of MIPK, then the material balance line runs into the distillation boundary. Alternatively, if the column is operated to obtain a high recovery of MIPK (by removing the MEK-water azeotrope as distillate), the material balance requires the bottoms to lie on the water-MIPK face of the triangle.

The number of saddles in a particular distillation region can have significant impact on column-profile behavior, process stability, and convergence behavior in process simulation of the system. Referring to the MIPK-MEK-water system in Fig. 13-58b, Region I contains one saddle (MIPK-water azeotrope), while Region II contains two saddles (pure MEK and the MIPK-water azeotrope). These are three-and "four-sided" regions respectively. In a three-sided region, all residue curves track toward the solitary saddle. However, in a four (or more) sided region with saddles on either side of a node, some residue curves will tend to track toward one saddle, while others track toward another opposite saddle. For example, residue curve 1 in Region I originates from the MEK-water azeotrope low-boiling node and trav els first toward the single saddle of the region (MIPK-water azeotrope) before ending at the water high-boiling node. Likewise, residue curve 2 and all other residue curves in Region I follow the same general path.

In Region II, residue curve 3 originates from the MEK-water azeotrope, travels toward the MIPK-water saddle azeotrope, and ends at pure MIPK. However, residue curve 4 follows a completely different path, traveling toward the pure MEK saddle before ending at pure MIPK. Some multicomponent columns have been designed for operation in four-sided regions with the feed composition adjusted so that both the high-boiling and low-boiling nodes can be obtained simultaneously as products. However, small perturbations in feed composition or reflux can result in feasible operation on many different residue curves that originate and terminate at these compositions. Multiple steady states and composition profiles that shift dramatically from tracking toward one saddle to the other are possible [Kovach, and Seider, AlChE J., 33, 1300 (1987). Consider a column operating in Region II of the MIPK-MEK-water diagram. Fig. 13-62 shows the composition and temperature profiles for the column operating at three different sets of operating conditions and two feed locations as given in Table 13-17. The desired product specification is 97 mol % MIPK, no more than 3 mol % MEK, and less than 10 ppm residual water. For Case A (Fig. 13-62a), the column profile tracks up the water-free side of the diagram. A pinched zone (area of little change in tray temperature and composition) occurs between the feed tray (tray

Temp. Profile

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