Part IV ：Enhancements to Single-Loop PID Feedback Control

@ Control enhancements are chosen based on the following criteria: Reinforce principles: ‘strong’ control theory Demonstrate practice Apply process insight: understanding of process equipment and operating conditions

Chapter 14 Cascade Control Cascade uses an additional measurement of a process variable to assist in the control system @ Cascade design criteria

Ex. Stirred-tank heat exchanger with cascade control

S1. Cascade control is superior to single-loop control

S2. Cascade controller S3. Two controller names

S4. Block diagram

@ Rejection of stochastic secondary disturbance Cascade control

Cascade examples 1. Packed-bed reactor

2. Heater exchanger 3. Pressure control

4. Jacketed CSTR

@ Distributed decision making by cascade structure