Episode 56 : Simulation for design and analysis Separation of an azeotropic mixture Mixture analysis Identification of an azeotrope. Possible separation techniques Pressure swing. Extractive/azeotropic distillation. Solvent identification and validation Flowsheet configuration SAJJAD KHUDHUR ABBAS Ceo , Founder & Head of SHacademy Chemical Engineering , Al-Muthanna University, Iraq Oil & Gas Safety and Health Professional – OSHACADEMY Trainer of Trainers (TOT) - Canadian Center of Human Development

1. SAJJAD KHUDHUR ABBAS
Ceo , Founder & Head of SHacademy
Chemical Engineering , Al-Muthanna University, Iraq
Oil & Gas Safety and Health Professional – OSHACADEMY
Trainer of Trainers (TOT) - Canadian Center of Human
Development
Episode 56 : Simulation
for design and analysis

2. Simulation for design and analysis (I)
Separation of an azeotropic mixture
• Mixture analysis
Identification of an azeotrope.
• Possible separation
techniques Pressure swing.
Extractive/azeotropic distillation.
• Solvent identification and validation
• Flowsheet configuration

3. Mixture analysis
Whenever you have the problem of separating a mixture, a good starting
point is always to do a mixture anaysis.
This can include both pure component and mixture properties.
The mixture analysis will imediately give information both intuitively
and to a computer aided system on what kind of separation is possible.
Binary Azeotrope:
A binary azeotrope is when a 2 component, 2 phase system of gas and liquid in
chemical equilibrium has the same composition in both phases.
Gas phase, composition: ya, yb
Liquid phase, composition: xa, xb
Azeotropic condition:
xa = ya, xb = yb

4. Identification of an azeotrope
Azeotropes is found by VLE (Vapor-Liquid Equilibria) mixture analysis.
This can be either database lookup for VLE datapoints or the datapoints can be
calculated with a thermodynamic model.
0 1
0
Comp A 1
x
y
Comp A
By the definition of an azeo-
trope, in a x-y plot the curve
crosses the diagonal, at the
azeotrope composition.

5. Acetone - chloroform
0
10
30
54
20
40
50
0
CHCl3
20 40 60
mole %
80 100
ACETONECHCl3
CHCl3mole%ACETONE
70
60
60
80
90
100
VLE-PhaseDiagram: Pres.= 1.00 atm
ACETONE
50
52
56
58
62
64
0
CHCl3
20 40 60
ACETONE
80 100
VLE-PhaseDiagram: Pres.= 1.00 atm
Temperature(°C)
Azeotrope ~ 38 mole% acetone, 64.5 °C, maximum boiling

6. Possible separation techniques
Conventional distillation not possible, if 2 pure products are desired.
Possible solutions to this problem:
•Use separation techniques which are not exploiting differences
in vapor vs. liquid phases, i.e. membranes or liquid- liquid
extraction.
• Pressure swing.
• Extractive / azeotropic distillation.

7. Pressure swing
Pressure swing distillation is exploiting the fact that for
some azeotropes the composition changes with pressure
0
20
40
60
80
100
0
METHANOL
20
METHANOL
40 60 80
CH3-ACETATE
100
VLE-PhaseDiagram: Pres.= 1.00 atm
mole %
METHANOLmole%CH3-ACETA
CH3-ACETATE
0
20
40
60
80
100
0
METHANOL
20
METHANOL
40 60
mole %
80 100
CH3-ACETATE
VLE-PhaseDiagram: Pres.= 6.00 atm
METHANOLmole%CH3-ACETA
CH3-ACETATE

8. Extractive distillation
70
60
50
40
30
20
10
0
90
100
The addition of a third component (solvent/entrainer) to the
binary system in order to facilitate the separation by distillation.
VLE-PhaseDiagram: Pres.= 1.00 atm solvent mole %
0
CHCl3
20 40 60 80 100
Vapour
Diagonal
Vapour 60.0
CHCl3 mole % ACETONE
CHCl3mole%ACETONE
ACETONE

9. Solvent identification (I)
The solvent can be found in a solvent database or by the use
of a computer tool.
The computer tool must be able to solve the following problem:
Given:
Needed:
A set of desired properties (pure and mixture)
Description of compounds with these properties
Computer Aided Molecular Design (CAMD) programs can solve
this.
General functionality:
1. Combine molecular fragments to describe complete molecules
2. Predict the properties of the molecular descriptions
3. Reject descriptions with undesired properties

10. Solvent identification (II)
Desired properties for the entrainer:
1.If it is a minimum boiling azeotrope the boiling point of
the entrainer should be lower than the azeotropic
temperature and vice versa.
2.The boiling point should not be to high in order to have
small energy consumption.
3. Should not be harmful to the environment.
4.Should not form azeotropes with any of the two
compounds.
5. High selectivety: S 
6. Low solvent loss: S 
7. ...
iS
jS
s
 
 
 sJ
sv.L
1

11. Solvent validation (I)
( 331.0 K) 0.0 0.1 0.2 0.3 0.4
328.1 K
0.5 0.6 0.7 0.8 0.9 1.0( 338.0 K)
METHYL-ACETATE METHANOL
1-PROPANAL
( 321.5 K)
1.0
0.9
Azeotrope
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0

12. Solvent validation (II)
0.0
( 331.0 K) 0.0
0.3
0.2
0.1
0.1 0.2 0.3 0.4
328.1 K
0.4
0.5
0.5 0.6 0.7 0.8 0.9
0.9
Azeotrope
0.8
0.7
0.6
1.0
1.0( 338.0 K)
1-PROPANAL
( 321.5 K)
METHYL-ACETATE METHANOL
Feed 1
D1, Feed 2
B1
D2
B2

13. Flowsheet configuration
B
A, B, Solvent
A
Solvent
A, Solvent
The flowsheet is fixed, and consists of to columns to
allow solvent recycle.

14. Thanks for Watching
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