Chapter 5- Dynamic Behavior, PPT, Chemical Engineering, Semester, Engineering Computer Science Engineering (CSE) Notes | EduRev

Created by: Prof Amit Gupta

Computer Science Engineering (CSE) : Chapter 5- Dynamic Behavior, PPT, Chemical Engineering, Semester, Engineering Computer Science Engineering (CSE) Notes | EduRev

The document Chapter 5- Dynamic Behavior, PPT, Chemical Engineering, Semester, Engineering Computer Science Engineering (CSE) Notes | EduRev is a part of Computer Science Engineering (CSE) category.
All you need of Computer Science Engineering (CSE) at this link: Computer Science Engineering (CSE)

Dynamic Behavior

 

In analyzing process dynamic and process control systems, it is important to know how the process responds to changes in the process inputs.

A number of standard types of input changes are widely used for two reasons:

 

  1. They are representative of the types of changes that occur in plants.
  2. They are easy to analyze mathematically.

 

Dynamic Behaviour------------------------------------------------Next Slide

 

  1. Step Input

A sudden change in a process variable can be approximated by a step change of magnitude, M:

Chapter 5- Dynamic Behavior, PPT, Chemical Engineering, Semester, Engineering Computer Science Engineering (CSE) Notes | EduRev

 

The step change occurs at an arbitrary time denoted as t = 0.

  • Special Case: If M = 1, we have a “unit step change”. We give it the symbol, S(t).

  • Example of a step change: A reactor feedstock is suddenly switched from one supply to another, causing sudden changes in feed concentration, flow, etc.

 

Dynamic Behaviour------------------------------------------------Next Slide

 

Example:

The heat input to the stirred-tank heating system in Chapter 2 is suddenly changed from 8000 to 10,000 kcal/hr by changing the electrical signal to the heater. Thus,

Chapter 5- Dynamic Behavior, PPT, Chemical Engineering, Semester, Engineering Computer Science Engineering (CSE) Notes | EduRev

2. Ramp Input

  • Industrial processes often experience “drifting disturbances”, that is, relatively slow changes up or downfor some period of time.

  • The rate of change is approximately constant.

 

Dynamic Behaviour------------------------------------------------Next Slide

 

We can approximate a drifting disturbance by a ramp input:

Chapter 5- Dynamic Behavior, PPT, Chemical Engineering, Semester, Engineering Computer Science Engineering (CSE) Notes | EduRev

Examples of ramp changes:

  1. Ramp a setpoint to a new value. (Why not make a step change?)
  2. Feed composition, heat exchanger fouling, catalyst activity, ambient temperature.

 

Dynamic Behaviour------------------------------------------------Next Slide

3. Rectangular Pulse

It represents a brief, sudden change in a process variable:

Chapter 5- Dynamic Behavior, PPT, Chemical Engineering, Semester, Engineering Computer Science Engineering (CSE) Notes | EduRev

Examples:

  1. Reactor feed is shut off for one hour.
  2. The fuel gas supply to a furnace is briefly interrupted.

 

Dynamic Behaviour------------------------------------------------Next Slide

 

Chapter 5- Dynamic Behavior, PPT, Chemical Engineering, Semester, Engineering Computer Science Engineering (CSE) Notes | EduRev

 

Dynamic Behaviour------------------------------------------------Next Slide

 

Other Inputs

4.  Sinusoidal Input

Chapter 5- Dynamic Behavior, PPT, Chemical Engineering, Semester, Engineering Computer Science Engineering (CSE) Notes | EduRev

 

Dynamic Behaviour------------------------------------------------Next Slide

 

Processes are also subject to periodic, or cyclic, disturbances. They can be approximated by a sinusoidal disturbance:

Chapter 5- Dynamic Behavior, PPT, Chemical Engineering, Semester, Engineering Computer Science Engineering (CSE) Notes | EduRev

Examples:

  1. 24 hour variations in cooling water temperature.
  2. 60-Hz electrical noise (in USA!)

 

Dynamic Behaviour------------------------------------------------Next Slide

 

For a sine input (1st order process)

Chapter 5- Dynamic Behavior, PPT, Chemical Engineering, Semester, Engineering Computer Science Engineering (CSE) Notes | EduRev

 

Dynamic Behaviour------------------------------------------------Next Slide

 

Inverting,

Chapter 5- Dynamic Behavior, PPT, Chemical Engineering, Semester, Engineering Computer Science Engineering (CSE) Notes | EduRev

note: φ is not a function of t but of τ and ω.

For large t, y(t) is also sinusoidal, output sine is attenuated by…

Chapter 5- Dynamic Behavior, PPT, Chemical Engineering, Semester, Engineering Computer Science Engineering (CSE) Notes | EduRev (fast vs. slow ω)

Dynamic Behaviour------------------------------------------------Next Slide

5. Impulse Input

  • Here, Chapter 5- Dynamic Behavior, PPT, Chemical Engineering, Semester, Engineering Computer Science Engineering (CSE) Notes | EduRev
  • It represents a short, transient disturbance.
  • It is the limit of a rectangular pulse for tw→0 and h = 1/tw

Examples:

  1. Electrical noise spike in a thermo-couple reading.
  2. Injection of a tracer dye.

Here,Chapter 5- Dynamic Behavior, PPT, Chemical Engineering, Semester, Engineering Computer Science Engineering (CSE) Notes | EduRev

 

 

Dynamic Behaviour------------------------------------------------Next Slide

 

Second order process example, Example 4.2

Chapter 5- Dynamic Behavior, PPT, Chemical Engineering, Semester, Engineering Computer Science Engineering (CSE) Notes | EduRev

note when Ce → 0, obtain 1st order equation (simpler model)

 

Dynamic Behaviour------------------------------------------------Next Slide

 

Block Notation:

 

Chapter 5- Dynamic Behavior, PPT, Chemical Engineering, Semester, Engineering Computer Science Engineering (CSE) Notes | EduRev

 

Dynamic Behaviour------------------------------------------------Next Slide

 

Chapter 5- Dynamic Behavior, PPT, Chemical Engineering, Semester, Engineering Computer Science Engineering (CSE) Notes | EduRev

 

Dynamic Behaviour------------------------------------------------Next Slide

 

Chapter 5- Dynamic Behavior, PPT, Chemical Engineering, Semester, Engineering Computer Science Engineering (CSE) Notes | EduRev

 

Dynamic Behaviour------------------------------------------------Next Slide

 

Chapter 5- Dynamic Behavior, PPT, Chemical Engineering, Semester, Engineering Computer Science Engineering (CSE) Notes | EduRev

 

Dynamic Behaviour------------------------------------------------Next Slide

 

Second Order Step Change

Chapter 5- Dynamic Behavior, PPT, Chemical Engineering, Semester, Engineering Computer Science Engineering (CSE) Notes | EduRev

Dynamic Behaviour------------------------------------------------Next Slide

 

Chapter 5- Dynamic Behavior, PPT, Chemical Engineering, Semester, Engineering Computer Science Engineering (CSE) Notes | EduRev

 

Share with a friend

Content Category

Related Searches

Objective type Questions

,

shortcuts and tricks

,

Chapter 12 - Experimental Methods - Chapter Notes, Chemical Engineering, Semester

,

PPT

,

Engineering Computer Science Engineering (CSE) Notes | EduRev

,

Chemical Engineering

,

Chapter 15 - Porous Media - Chapter Notes, Chemical Engineering, Semester

,

Previous Year Questions with Solutions

,

Chapter 5- Dynamic Behavior

,

Chapter 7 Dryers - Chapter Notes, Chemical Engineering, Semester

,

Summary

,

MCQs

,

Semester

,

Chemical Engineering

,

pdf

,

Chapter 5- Dynamic Behavior

,

Engineering Computer Science Engineering (CSE) Notes | EduRev

,

Semester

,

Sample Paper

,

Important questions

,

PPT

,

study material

,

Engineering Computer Science Engineering (CSE) Notes | EduRev

,

practice quizzes

,

Free

,

mock tests for examination

,

Semester Notes

,

Chapter 11 - Heat Exchangers - Chapter Notes, Chemical Engineering, Semester

,

ppt

,

Chapter - Batch Processing, PPT, Chemical Engineering, Semester, Engineering

,

Chapter 5- Dynamic Behavior

,

video lectures

,

Chemical Engineering

,

Exam

,

PPT

,

past year papers

,

Viva Questions

,

Extra Questions

,

Semester

;