Optimizing Product Quality Performance ◾  71
7.5 If the upper specification limit for the heavy key impurity in the distillate is 0.5% and the upper spec limit for
the light key impurity in the bottoms is 0.2%, which
rule would fire in Table 7.2 if the distillate sample
analyzed 0.35% heavy key impurity and the bottoms
sample analyzed 0.1% light key impurity?
7.6 If Rule No. 4 fired in Table 7.2, should the temperature
setpoint be raised, lowered, or left unchanged?
7.7 How large of a temperature change in setpoint would
be recommended by Table 7.2 if the temperature gradient for the controlled temperature is 5°C per theoretical
stage?
References
1. Montgomery, D. C., and Runger, G. C., Applied Statistics and
Probability for Engineers, John Wiley & Sons, New York, 1994.
2. Robinson, J. W., Improve dryer control, CEP, 28–33, December
1992.
3. Parkinson, G., Optimizing distillation columns via the Internet,
Chem. Eng. Vol. 108, No. 11, October 23–25, 2001.