1. Workshop for Flipped Class Performance of Feedback Control Systems
Based on students having completed the Chapter 13 e-Lesson before class
Chapter 13 Part II
Performance of Feedback Control Systems
CAUTION: This workshop involves complex problems integrating process design and control. Please recognize that we must encountered these challenges to be able to address realistic engineering problems.
Copyright © Thomas Marlin 2016

2. CHAPTER 13. FEEDBACK PERFORMANCE
Feedback dynamics : The sketch shows a series of heat exchangers to reheat a distillation tower feed.
Discuss the relative cost of each of the sources of heat. (Hint: think about the second law and economics.)
Design the control design giving the best control performance for T-2.
Modify your design in (2) to give (nearly) the best economic performance.
Source T3 v1
T5 > T4 > T3
Source T4
Source T5 v3 v4
Cold feed
Source T3
Hot feed v2 TC 2
To v?

3. CHAPTER 13. FEEDBACK PERFORMANCE
By-Pass Principle: In the e-Lesson, we learned that the by-pass designs provide fast feedback dynamics for temperature control. Can we apply this principle to other chemical processes?
Stream A
(cold)
Stream B
(hot) T
Stream A
(cold)
Stream B
(hot) TC
Simplest approach. Can be slow.
Stream A
(cold)
Stream B
(hot) TC
By-pass approach.:
More costly; much faster.

4. CHAPTER 13. FEEDBACK PERFORMANCE
By-Pass Principle: In the e-Lesson, we learned that the by-pass designs provide fast feedback dynamics for temperature control. Can we apply this principle to other chemical processes?
Distillation: Do we separate and remix to achieve product purity? AC

5. CHAPTER 13. FEEDBACK PERFORMANCE
By-Pass Principle: In the e-Lesson, we learned that the by-pass designs provide fast feedback dynamics for temperature control. Can we apply this principle to other chemical processes?
Do we apply the by-pass approach to other processes?
Chemical reactor: React and remix to achieve product concentration of valuable component “B”?
A  B  C

6. CHAPTER 13. FEEDBACK PERFORMANCE
By-Pass Principle: By-passes to regulate temperature is a proven technique.
What did we learn about temperature dynamics in the following design with an exothermic reaction and feed-effluent heat exchanger?
How can by-pass control improve the dynamic behavior?

7. CHAPTER 13. FEEDBACK PERFORMANCE
Equipment Principles: Determine whether the proposed flow control design is consistent with equipment performance principles.

8. CHAPTER 13. FEEDBACK PERFORMANCE
Equipment Principles: Determine whether this control design is consistent with process equipment principles.
Vapor
product T6
PC1 T5 T1 T2 F1 T4 T3 L1
Cool Liquid
Product to tank T7 F2 F3 v4 v6 A1
Process
fluid
Steam
c.w.
L. Key

9. CHAPTER 13: CONTROL PERFORMANCE Workshop 7: Symmetric Process Dynamics
The two figures on this slide show two methods for controlling an exit temperature in a steam-heated exchanger. Explain how the adjustment of the control valve opening affects the heat transferred; also, select the design with the best temperature control performance. TC TC