Elements of
Chemical Reaction Engineering
6th Edition



Home

Essentials of
Chemical Reaction Engineering
Second Edition

  Select  Chapter  >>     TOC     Preface     1     2     3     4     5     6     7     8     9     10     11     12     13     14     15     16     17     18     Appendices  
›

By Chapter Hide

  • Objectives
  • Living Example Problems
  • Extra Help
  • - Summary Notes
  • - LearnChemE Screencasts
  • - FAQs
  • - Interactive Computer Modules
  • Additional Material
  • Self Test
  • i>Clicker Questions
  • Professional Reference Shelf

By Concept Hide

  • Interactive Modules
  • -Web Modules
  • -Interactive Computer Games
  • Living Example Problems

U of M Hide

  • Asynchronous Learning
  • ChE 344
  • ChE 528

Chapter 13: Unsteady State Nonisothermal Reactor Design

Example DVD13-4: Proportional Integral Control

 

Repeat Example CDE13-2 using a proportional-integral controller instead of only an integral controller.

  
     
 




Solution

  
     
 

We note that while the output temperature returns to 138°F, the temperature oscillates over a 20°F range, which may be unacceptable in many situations. To overcome this we will add proportional to integral control. The equations here to be added to those in Table CDE13-2.1 to represent the PI controller are

  
     
 

image 09eq50.gif

(CDE13-4.1)



(CDE13-4.2)
     
 

with the exception of the perturbation variable and the variable being controlled.

(Note that all equations are the same as before.)

We will set the kC 8.5 andI =av = 0.165 hr. We see that the output outlet temperature does not oscillate as much as with just an integral controller. Try different controllers (differential, proportional, integral) and combinations thereof, along with different parameter values to study the behavior of CSTRs which have upsets to their system (Figures CDE13-4.1 and CDE13-4.2).

 
 
TABLE CDE13-4.1
Polymath Program



Figure CDE13-4.1
Temperature Time Trajectory



Figure CDE13-4.2
Temperature conversion phase plane plot