Figure 5.22 Effect of KEQ.

Figure 5.24 Effect of KEq on composition profiles.

composition affects the design of the reactive distillation column. Of course, the limiting case with z0A(A) = 1 and Zoa(i> = 0 was already studied in Section 5.1 (no inerts). We would expect that it should be easier to achieve the desired conversion as the amount of inerts in the feed decreases.

Figure 5.25 shows that this is true. The upper graphs show that both vapor boilup and fresh feed F0A decrease as less inert enters in the feed. Of course, the distillate flowrate also decreases because there is less inert to remove.

The specified value of the concentration of A on tray 6 has been changed as z0A(A) is changed. With no inerts in the system (z0A(A) = 1), the composition on tray 6 is 10 mol% A. In Section 5.2.5 we found that a tray 6 composition of about 30mol% A is reasonable for the case where z0A(A) is 0.5. Therefore, values of 20 and 25 mol% A are used for the specified composition on tray 6 for the cases with z0A(A) = 0.70 and 0.60, respectively.

Figures 5.26 and 5.27 give the temperature and composition profiles for three values of z0A(A). The most striking feature in these plots is the higher temperature when z0A(A) = 0.7, which is caused by the much higher concentrations of component B and the lower concentrations of I throughout the column (right graphs, Fig. 5.27). The B composition profile should be compared with that shown in Figure 5.2, which has no inerts. The same high concentration of B can be observed.

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