132 ◾  Index
frequency of failure and, 59–60
optimization of MRT and,
60–62
reduction of variability and,
63–65
Quality performance measurement,
58
Quarter decay ratio (QDR)
tuning of control loops, 85–86
tuning rules, 112
R
Raoult’s law, 14
Rate action, calculation of for
feedback control loop, 77
Rectification, 20–21, 39
mass transfer constraint, 50–53
measuring quality performance
of, 58
stages and gas mass transfer
units for, 52
Reflux, constraint of and system
optimization, 67–68
Reflux drum, level controllers for,
99–102
Reflux flow rate, temperature
control with, 37–38
Reflux ratio, 10
Reflux/feed ratio, use of to set
separation power base, 20
Relative volatility, single theoretical
stage, 13–16
Reset action
calculation of for feedback
control loop, 76
effect of, 93–99
Ringing, 92
Robbins tuning method
pattern recognition for level
controllers, 99–102
self-regulating control loops,
86–90
S
Scientific method, 2
Self-regulating control loops
calculation of process gain, 98
correlation for minimum IAE in,
97
pattern recognition tuning of,
86–90
Self-regulating process response,
80, 106–107
Separation power
constraints on, 46
energy consumption and, 18–20
key impurity, 17–18
multiple stages, 16–18
origin of in a distillation column,
13
relative volatility in single stage,
14–16
Separation power base
derivation of from reflux/feed
ratio, 39–40
establishment of with steam/feed
ratio, 36, 38
expert system rules and
optimization of, 65–66
reflux ratio and, 10
setting for distillation control,
20
Series algorithm for PID controllers,
77
Setpoint, 74
control loop response to change
in, 96
level control response to change
of, 101
Side draw flow rate, 41
SISO (single input single output)
control, 36
Slave flow control loop
use of in bottoms control
scheme, 40