128 ◾  Index
Constraints
expert system optimization rules
and, 67–68
heat transfer, 47
hydraulic, 46
mechanical, 45–46
rectification mass transfer, 50–53
stripping mass transfer, 47–50
Continuous binary distillation
columns, inlet streams in,
8–9
Control loops
oscillating, 84–85
pattern recognition tuning of
integrating, 99–102
pattern recognition tuning of
self-regulating, 86–90
quarter decay ratio tuning of,
85–86
response of to load change, 95
response of to setpoint change,
96
response with optimum gain,
90–93
trial-and-error tuning of, 81–82
ultimate gain tuning of, 82–84
Control strategies, 34
boilup scheme, 38–40
bottoms flow rate, 40
column pressure control, 34
distillate vapor flow rate, 42–43
manipulated distillate control,
34–37
reduction of variability and
selection of, 63
side draw flow rate, 41
temperature control with reflux
flow rate, 37–38
Control valves, constraints due to
trim size in, 46
Controlled variables, 9–10
Cycling control loop,
troubleshooting, 84–85
Cyclohexane, mole percent of at
total reflux, 16
Cyclohexane/n-heptane, vaporliquid equilibrium data for,
14–15
D
D-POP (Distillation Performance
Optimization Program),
68
Dead time response, 106
determination of, 109
Derivative action, calculation of for
feedback control loop, 77
Derivative time constant, 77
Distance from nearest specification
limit (DNS)

calculation of, 59

optimum, 63

Distillate flow rate, temperature
control with, 34–37
Distillate vapor flow rate, 42–43
Distillate/feed (D/F) material
balance split, 46–47
determination of, 24
Distillate/feed (D/F) ratio, 20, 23
expert system rules and
optimization of, 65–66
temperature change from shift
in, 27–29
Distillates
expert system rules and
optimization of, 65–66
heavy key in, 17
interaction of with bottoms
stream, 25–26
optimization of MRT and quality
of, 60–62
optimization rules when steam
or reflux is constrained,
67–68
quality measurements, 58