124 ◾  Appendix: Solutions to Chapter Exercises
Exercise 7.4
The separation power base could be reduced to reduce
energy consumption, and let the impurity concentrations
increase in the distillate and bottoms.
Exercise 7.5
Rule No. 5 would fire.
Exercise 7.6
Lowered.
Exercise 7.7
0.3(5) = 1.5°C.
Exercise 8.1
CO = change in PV times K c = 5% (5) = 25% change in controller output.
Exercise 8.2
For Equation 8.1,

K c = 12.5 and

CO − CO b = 7% change in steam valve position.

So, e = 7/12.5 = 0.56% of temperature span

And (0.56/100)(200°C) = 1.12°C offset

The new steady-state temperature would be too low.