Dividing wall column application
in heterogeneous azeotropic distillation
(In collaboration with PERSTORP, SWEDEN)
Supervisor: Sigurd Skogestad
Student : LE Quang Khoa
1
INTRODUCTION
Dividing wall column is an application of thermally coupled Petlyuk column
arrangement. This technology allows a significant energy reduction for
separation of multicomponent.
Heterogeneous azeotropic distillation is used in industry to separate close boiling
point mixture and azeotropes.
The system: Cyclohexanone, Water, Acetic Acid and heavy organics.
Cyclohexanone, Water and Acetic Acid build a two liquid phase system
Objective of project : Design and simulate ternary hetero-azeotropic distillation
column in combination with deviding wall column.
2
PROJECT CHRONOLOGY
Step 1: Rebuild and simulate the conventional arrangement using
Aspen Plus
Step 2: Optimize the conventional arrangement
Step 3: Design and simulate heterogeneous azeotropic
distillation column via dividing wall column
3
Step 1: Rebuild and simulate the conventional arrangement
Conventional arrangement
AA is Acetic Acid, CH is Cyclohexanone, W is Water and HE is Heavy Organics
4
Step 1: Rebuild and simulate the conventional arrangement
VAPOR LIQUID EQUILIBRIUM ANALYSIS
NRTL-HOC is chosen as thermodynamic model for the given system
Origin
Cyclohexanone1-acetic Acetic acid1-
Cyclohexanone1-
acid2
water2
water2
Regression to data
Regression to
Regression to data
data
B12
1715.54
255.44
-164.59
B21
113.07
19.412
1568.59
Α
1.267
0.3
0.2
Equilibrium data for the ternary system cyclohexanone- acetic acid- water were
carried out in Perstorp
Caprolactone and heavies activities are predicted in UNIFAC
5
Step 1: Rebuild and simulate the conventional arrangement
VLE of Water/acetic Acid system
1
0.9
vapor mole fraction of Water
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
liquid mole fraction of Water
Aspen modified NRTL HOC
experiemental values
6
Step 1: Rebuild and simulate the conventional arrangement
VLE of Water/Cyclohexanone system
1.2
vapor mol fraction of Water
1
0.8
0.6
0.4
0.2
0
0
0.2
0.4
0.6
liquid mole fraction of Water
0.8
1
1.2
Aspen modified NRTL Hoc
experimental values
7
Step 1: Rebuild and simulate the conventional arrangement
A CETI-0 1(118 .01 C )
T e r na r y M a p ( M a s s B a s is )
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
CYCLO-01
(155 .42 C )
97.01 C
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
WA TER
(100 .02 C )
8
Step 2: Optimization of the conventional arrangement
AZEOTROPIC
COLUMN
Operation condition: Feed entering into the stage 25.
Total number of stage is 50.
The feed stage is fixed ratio of the total number of stage (0.5)
9
Step 2: Optimization of the conventional arrangement
1/ Feed stage :
analysis of feed stage
3147.8
3147.7
3147.6
reb_tot (kW)
3147.5
3147.4
3147.3
3147.2
3147.1
3147
3146.9
3146.8
0
5
10
15
20
25
30
35
40
stage number
Stage No 25
45
Step 2: Optimization of the conventional arrangement
2/ Total number of stage :
The feed stage is fixed ratio of the total number of stage (0.5)
Total No of
stage
FEED STAGE
TOT_REB
44
22
3147.464
45
22
3147.182
46
23
3146.942
47
23
3147.127
48
24
3147.106
50
25
3145.964
51
25
3145.966
53
27
3147.024
54
27
3146.999
“Optimum”
11
Step 2: Optimization of the conventional arrangement
3/ Water reflux ratio:
( 90% of water, 10% of Cyclohexanone):
analysis of water ref ratio
12000
10000
reb_duty( kW)
8000
6000
4000
2000
0
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
water reflux ratio
12
13