Index ◾  129
Distillation column control, 8

response times for variables in, 99

separation power base setting
for, 20

Distillation columns

column base levels for, 99–102

high steam consumption in, 63

high tray temperature in, 61

low tray temperature in, 62

optimization of using expert
systems, 65–69

quality performance in, 61

quality performance of a stream
from, 59–60

reduction of variability in, 64

rule of thumb for economical
design of, 17–18

separation power in, 13–16

Distillation process control,
application of scientific
method to, 3

Distillation systems

inlet streams in, 8–9

outlet streams from, 9

Dividing Wall Column (DWC),
41–42
DNS. See Distance from nearest
specification limit
Dynamic matrix control, 65

E
Economic return, optimization of
for distillation columns,
63–64
Energy consumption

requirements for doubling key
impurity separation power,
20

separation power and, 18–20

Environmental disturbances

effect of on boilup control
scheme, 39

effect of on manipulated
distillate control scheme,
36

effect of on reflux control
scheme, 38

Error, 74

Expert system advisors,
optimization using, 65–69
F
Failure, frequency of, 59–60
Feed streams, 23, 25–26
effect of changes in, 27–29
Feedback control loop, 74. See also
Control loops

derivative action, 77

integral action, 76

proportional action, 75–76

Fenske equation, 17

First-order capacitance lag, 106

First-order filter constants, 107

First-order plus dead time (FOPDT)
response, 106

two-point characterization of,
110–112

First-order time constant (TFO),
determination of, 111

Flooding, 45–46

Flow rate, 10

reflux control scheme, 37–38

side draw, 41

G
Gas transfer units, calculation of
for theoretical stages in
rectification, 52–53
H
Heat transfer, constraints, 47

Heavies, weight fraction of, 24–25