Figure 10.7 shows the responses of the CS7-RR structure for +1% and +5% changes in vapor boilup. The responses are very oscillatory because of the very small steady-state gain of tray 10, which is the tray recommended by SVD calculations.
However, note that the product purities remain fairly close to the desired 95% level, even for the +5% change in vapor boilup. This suggests that the CS7-RR structure should perform better than the CS7-R structure if the dynamics can be improved. The next section demonstrates that this can be achieved by using a suboptimal steady-state design that has more reactive trays.
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