CBE / MET 433

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

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

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….

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

P & ID Symbols (App. A)

P & ID Symbols (App. A)

Examples

ID: Process lines…..Control loops

Example: * *1136 W/m2-K

Controlled Variables: Manipulated Variables:

Controller Action

Valve Action

Thermodynamic Behavior