Control Project 2 - Part 1

7/30/2019 Control Project 2 - Part 1

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Process Control - Project 2

By:- Eng. Sahar Nasrallah

Supervised by:- Dr Deeb Abu Fara

Simulation a Plant-Wide Control System Using MATLAB

http:www.mathworks.com


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Project Objective

Project Description -Reactor/Distillation Column Plant-

Dynamic Process Modeling

What is Simulink ?

How to solve ODE using Simulink? (Simple Example)

What is your task ?

Lecture Outline


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Project Objective The objective of the project is to practice simulation a

plant-wide control system.


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Project Description


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Project DescriptionA mixture of two species, mainly A but also containing

some B, is fed to a reactor where the reaction A B

takes place isothermally.

The binary distillation column (DC) has 20 stages.

DC produces two product streams: an overhead

(distillate) stream rich in A and a (bottom) stream rich in

the desired product B.


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Project DescriptionThe A-rich distillate is recycled to the reactor to

increase the conversion of A to B.


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Project DescriptionAn Isothermal Reactor:-


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Project DescriptionA Distillation Column:-


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Project DescriptionA number of simpli f ications are used here:

1. The reaction rate is first order in A (Elementary RXN).

2. Reactor operation is isothermal (T = 0).

3. The column operates with equimolal overflow (L=V).

4. Column operation is at atmospheric pressure.

5. Constant relative volatility is used to describe vapor/liquid

equilibrium.

6. Each tray represents an equilibrium stage


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Dynamic Process ModelingReactor:

General Information:

Reaction rate expression is first order in reactant A.

A B

rA = -kRHRz

Reactor residence time,HR (Fo + D) = 2.5 hr


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Dynamic Process ModelingrA : rxn rate ( reactant A consumption rate)

kR : Specific reaction rate (rate constant), 0.33 h-1

HR : Reactor holdup, 2400 lb-mol

z : DC feed composition, 0.5 mole fraction A


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Model:

1. Total (overall) Mass Balance:

Accumulation = Inlet - Outlet

= Fo+ D - F (= 0 for perfect reactor level/mols control)


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Dynamic Process ModelingHR : Reactor holdup, 2400 lb-mol

Fo : Fresh feed 460, Ib-mol/h

F : Column feed rate, 960 lb-mol

D : Distillate flow rate, 500 lb-mol


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Model:

2. Individual Component (A) Mass Balance:

Accumulation = Inlet - Outlet + disappearance

()

= F0z0+ DxD - Fz + (-kRHRz) (= 0 for perfect

reactor level/mols control)


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Dynamic Process Modelingz0 : Fresh feed composition, 0.9 mole fraction A

XD : Recycle composition, 0.95 mole fraction A

z : Column feed composition, 0.5 mole fraction A


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Dynamic Process ModelingDistillation Column:

General Information:

i. Saturated liquid feed is to 12th stage (of 20)

numbered from the top down.

ii. Equimolal overflow is assumed. A is the more volatile

component; assume equilibrium holds for each stage:

yi = ( )/(1+)


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Drum Model:


Accumulation = InletOutlet + disappearance

()

= V-R-D (= 0 for perfect reactor level/mols control)

HD: Drum holdup 185 lb-mol


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Dynamic Process ModelingV : Vapor boilup, 1600 1 b-mol/h

R : Relux flow rate, 1100 Ib-mol/h

D : Distillate flow rate, 5001b-mol/h


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Drum Model:



()

= V(y20)R(xD)D(xD) ( 0 for perfect reactor

level/mol control)


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Dynamic Process Modelingy20 : The A concentration in the vapor outlet from tray 20

upper trayyi =

1+= 0.974

: Relative volatility, =2


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Stage i above feed Model:



xi()

= L(xi+1- xi )-V(yi - yi-1) for 13i 19


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Dynamic Process ModelingRectification Section

Hs: Individual stage holdup

Hs = 23.5 lb- mol

L=Li+1=Li=Li-1=R

V = Vi+1 = Vi = Vi-1


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Feed Stage:



x12()

= L(x13- x12)-V(y12 - y11) + F z


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Dynamic Process Modelingwhere

L =L + F

L: Liquid hold up =

R, 1100 Ib-mol/h

F : Column feed rate, 960 lb-mol/h


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Stage j below feed Model:



xj()

= L(xj+1- xj )-V(yj - yj-1) for 1 j11


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Dynamic Process ModelingStripping Section

Individual stage holdup,

Hs = 23.5 lb- mol

L=Lj+1=Lj=Lj-1=R+F =

L+F = 2060V = Vj+1 = Vj = Vj-1


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Bioler Model:



()

= L-V-B (= 0 for perfect reactor level/mols control)

HB: Boiler holdup 275 lb-mol


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Dynamic Process ModelingL : L+F = 2060 lb-mollh

V : Vapor boilup, 1600 lb-mol/h

B : Bottoms flow rate, 4601 b-mol/h


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Boiler Model:



()

= L(x1)V(yB)B(xB)

( 0 for perfect reactor level/mol control)


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What is Simulink ? What is the SIMULINK ?

1. Simulink is a tool for simulating dynamic systems with

a graphical interface specially developed for this purpose

within the MATLAB environment.

2. Simulink is a MATLAB toolbox that differs from the

other toolboxes, both in:

A. Its special interface .


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What is Simulink ? What is the SIMULINK ?

1. Simulink is a tool for simulating dynamic systems with

a graphical interface specially developed for this purpose

within the MATLAB environment.

2. Simulink is a MATLAB toolbox that differs from the

other toolboxes, both in:


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A. Its special interface .

B. Its special programmingtechnique .

C. The source code of the Simulink system is not open.

What is Simulink ?


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linear or nonlinear time-dependent processes (dynamic

systems that are continuous in time) can be described

using:

1. differential equations or (in the case of discrete times)

difference equations.

2. dynamic systems is with block diagrams, convert a

block diagram directly into Simulink and simulate the

operation of the system.

What is Simulink ?


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This is an attempt to understand the behavior of the

system by means of a graphical representation, which

essentially consists of representations of individual

components of the system together with the signal flowbetween these components.

What is Simulink ?


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Steps for solving Simulink problem :

1. Constructing a Simulink Block Diagram.

2. Parametrizing Simulink Blocks.

3. Simulink Simulation.

What is Simulink ?


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How to solve ODE using Simulink Example:

find the open loop response for the following of ODE

using Simulink toolbox.

=3+12

y(t) and x(t).


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How to solve ODE using Simulink Solution:


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How to solve ODE using Simulink


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What is you task ? Your task is to choose one or more of the alternatives

and perform simulation study using MATLAB

Simulink, to maintain the composition of B in the

product stream xB at the nominal value , 0.0105 mole

fraction, despite disturbances in the fresh feed

composition zO and the feed flow rate FO.


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Alternative 1 (Fig. 23.7a)

What is you task ?


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CSTR Model:

What is you task ?


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CSTR Model:

()

= F0z0+ DxD - Fz + (-kRHRz)

z()

+

()

= F0z0+ DxD - Fz + (-kRHRz)

()

=

[F0z0+ DxD Fz + (kRHRz)] z ()

where

()

= (Fo+D-F)

What is you task ?


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CSTR Model:

Inputs:

DFFoxD - zo

Outputs:

z - HR

What is you task ?


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Distillation Column Model:

What is you task ?


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CSTR-Distillation Column Model:

What is you task ?


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Thank You

Documents

Control Project 2 - Part 1