1. CBE / MET 433

2. Last lecture: 25 April 2012
Final: 3 May 2012; 11-12:50

3. Today Review feedback control Block diagram
P & ID (process and instrumentation diagrams)
Examples and exercises
Homework

4. Feedback Control measure some property compare to setpoint
decide what to do
change another property
Controlled Variable
Control Algorithm
Manipulated Variable
Change in the Manipulated Variable affects the Controlled Variable!
Feedback control:
Upset happens
Measured variable changes
Controller responds
Examples:
? Solicit ideas on how a controller works… i.e. house furnace….

5. Block Diagram Feedback Control Loop
measure some property
compare to setpoint
decide what to do
change another property
Loads
Flowrate
Temp or Level
Process
Action
Measure
Feedback Control Loop
error
Decision
Compare SP

8. P & ID Symbols (App. A)

12. P & ID Symbols (App. A)

16. Examples

18. ID: Process lines…..Control loops

20. Example: *
*1136 W/m2-K

21. Controlled Variables: Manipulated Variables:

23. Controller Action

24. Valve Action

27. Thermodynamic Behavior