SAMRS 2009/09/02
INTRODUCTION
Thermodynamic of air separation
-183.5
Using the PengRobinson equation
of state the
isobaric t, xy and
x,y diagrams of N2O2 and Ar-O2
binary systems at
different pressures
were calculated: P
= 1 .4 at
1
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0
0.2
0.4
0.6
0.8
0.9
1
0.8
0.7
Y
-184
t(°C)
Air at lower temperatures (-196oC) becomes in liquid and so
can do the distillation of air to its components. Distillation of
air is currently the most commonly used technique for
production of air component, in industrial scale. Air separation
plants are designed to generate oxygen, nitrogen and pure
argon from air through the process of compression, cooling,
liquefaction and distillation of air. As an experienced and
knowledgeable manufacturer of air separation plants with the
most advanced technology. Air also using for production of
oxygen gas, nitrogen gas, squeezed air, dry air for control and
automatisation of devices. The current work aims to describe
the air separation process including heat exchange and at 1.4 atmosphere: Figure 1 :T,X,Y- diagram,N2 – O
Ar – O2
cryogenic distillation. An ASPEN Plus simulation of cryogenic
air separation into Nitrogen, Oxygen and Argon is created. The
influence of different process parameters on distillation
efficiency is analyzed.
-184.5
0.6
0.5
0.4
-185
0.3
0.2
-185.5
0.1
-186
0
0
-186.5
0.2
0.4
X
Figure 2 :X,Y diagram,N2- O2
0.6
0.8
1
X
Figure 3 : T,X,Y- diagram, Ar- O2
Figure 4 : X,Y- diagram,
Aspen simulation of air separation process
Air separation technology scheme
Technical
specifications of KT
– 1000 M plant:
Volume flow of the
air m3/hr:
High pressure air
800 m3/hr at
pressure 160at
5321.4 kmol/hr
Low pressure air
3500 m3/hr at
pressure 5at
727.5 kmol/hr
Volume of
producted oxygen
1243.877 kmol/hr
Volume of
producted nitrogen
4760.309 kmol/hr
Volume of
producted Argon
44.714 kmol/hr
Mol fraction of
oxygen
98.7%
Mol fraction of
nitrogen
99.0%
Mol fraction of
Argon 99.9 %
Calculation of air distillation by McCabe-Thiele method
Figure 5: X-Y diagram, vapor and liquid N2
Capital investment costs of air distillation
Table 8: calculation of investment costs
Type
Direct Cost
NO
Name
Type
Direct
(USD)
Cost(USD)
1
B1
DGC CNTRIF
15726500
15
C3- reflux pump
DCP CENTRIF
34800
2
B2
DGC CNTRIF
2163300
16
C3-tower
DTW TRAYED
2758400
3
B4
DHE FLOAT HEA
90500
17
C4-cnod acc
DHT HORIZ DRU
127200
4
C1-cond acc
DHT HORIZ DRU
219500
18
C4-reb
DRB U TUBE
65400
5
C1- reflux pump
DCP CENTRIF
61200
19
C4-reflux pump
DCP CENTRIF
24100
6
C1- tower
DTW TRAYED
450700
20
C4-tower
DTW TRAYED
165900
7
C2- cond
DHE FIXED T S
572400
21
Expander
DTUR TURBOEX
63000
8
C2 -reb
DRB U TUBE
143000
22
HE1
DHE FLOAT HEA
294600
9
C2-reflux pump
DCP CENTRIF
338600
23
HE2
DHE FLOAT HEA
207200
10
C2-tower
DTW TRAYED
5183100
24
HE3
DHE FLOAT HEA
278700
11
C3-cond
DHE FIXED T S
25
HE4
DHE FLOAT HEA
374700
12
C3-cond acc
DHT HORIZ DRU
147600
26
HEN2
DHE FLOAT HEA
94000
13
C3- reb
DRB U TUBE
41600
27
HEO2
DHE FLOAT HEA
94000
28
total
14
total
25138000
TOTAL
Figure 6: scheme of the air separation
C1,C2,C3 are column 2 – S1,S2,S3,S4,S5,B8,B10 are mixers 3-HEO2,HEM2,HE1,HE2,HE3,HE4 are heat exchangers 4 – Expander
4582000
= 29720000 USD
90
80
70
60
R
Figure 37: Number of
theoretical stages versus
Reflux ration in column
C3 for, Argon purity: 0.99,
Argon recovery:0.999
100
50
40
30
20
10
0
50
60
70
80
90
100
110
120
130
140
150
Table 1:results of study state simulation of air distillation process
160
N
25
0.14
23
21
0.12
19
0.1
XAr C2
R C2
17
15
13
11
0.08
0.06
0.04
9
7
0.02
5
0
1100
1600
2100
2600
3100
3600
4100
4600
5100
1100
1600
2100
2600
nD C1
nD C1
3100
3600
4100
4600
5100
Composition profile
C3
This diagram shows
the composition of
oxygen , nitrogen and
Argon in different
stage number of
column 3.
Figure 6: Composition profile of column C3
1
0.9
0.8
0.7
0.6
0.5
N2
0.4
O2
0.3
AR
0.2
0.1
0
Optimization of distillation columns parameters
0
10
20
30
40
50
60
N
70
80
90
100
Temperature profile C3
This diagram shows the
temperature in different
stage of column C3.
It shows the temperature
will be higher up from
lower to the bottom of
column3
Figure 7:Temperature profile of column C3
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1
11
21
31
41
51
61
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-185
t( C)
Name
X
NO
-186
-187
-188
-189
110
-190
N
71
81
91
101
111
Scheme of the air separation process
C1,C2,C3 are column 2 – S1,S2,S3,S4,S5,B8,B10 are mixers 3HEO2,HEM2,HE1,HE2,HE3,HE4 are heat exchangers 4 – Expander, B1, B2 are
compressors, B3 and B4 coolers of compressors