TU Graz I Institute of Chemical Engineering and Environmental Technology Heidelberg, 16.03.2015Fachtagung Extraktion,
1
E. Cvetkovic
1
, A. Pfennig
2
1
Institute of Chemical Engineering and Environmental Technology
NAWI Graz, TU Graz
2
Département de Chimie Appliquée
Université de Liège
Stofftransport an Einzeltropfen mit
Konzentrationsprofil in der
kontinuierlichen Phase
Stofftransport an Einzeltropfen mit Konzentrationsprofil in der kontinuierlichen Phase
Outline
Single-drop measurements
Standard sedimentation and
mass-transfer cells
Cell with concentration profile
Experimental setup
Results
TU Graz I Institute of Chemical Engineering and Environmental Technology Heidelberg, 16.03.2015Fachtagung Extraktion,
3
Single-drop measurements
Sedimentation
Mass Transfer
Stofftransport an Einzeltropfen mit Konzentrationsprofil in der kontinuierlichen Phase
Single-drop sedimentation
rigid sphere
circulating
drop
oscillating drop
deformed drop
0
2
4
6
0
20
40
60
80
100
120
140
s
e
dim
ent
at
ion v
e
loc
it
y
[
m
m/
s
]
drop size [mm]
TU Graz I Institute of Chemical Engineering and Environmental Technology Heidelberg, 16.03.2015Fachtagung Extraktion,
5
Modelling of mass transfer
20
40
60
0,0
0,2
0,4
0,6
0,8
1,0
0
1
2
3
4
5
6
(y
-
y
*)
/
(y
0y
*)
dr
op
d
ia
m
et
er
in
m
m
time in
s
c
d
IP
d
eff
d
C
d
v
D
D
1
,
Henschke, Pfennig, AIChE J, 45, 10: 2079-2086, 2010
Stofftransport an Einzeltropfen mit Konzentrationsprofil in der kontinuierlichen Phase
Concentration profile
Measurement cell vs. extraction column
height
concentration
concentration
height
phase:
continuous
dispers
phase:
continuous
dispers
TU Graz I Institute of Chemical Engineering and Environmental Technology Heidelberg, 16.03.2015Fachtagung Extraktion,
7
Single-drop cell with concentration profile
Material system:
butylacetate +
water +
acetone
8%
6%
4%
2%
Stofftransport an Einzeltropfen mit Konzentrationsprofil in der kontinuierlichen Phase
Validation – Sedimentation
0
2
4
6
0
20
40
60
80
100
120
140
butylacetate-droplets in water:
without dye (this work)
with dye (this work)
reference (Henschke, 2003)
s
e
d
im
ent
ati
on v
e
lo
c
it
y
[m
m
/s
]
drop size [mm]
TU Graz I Institute of Chemical Engineering and Environmental Technology Heidelberg, 16.03.2015Fachtagung Extraktion,
9
Reproducibility
Concentration profile
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
0
10
20
30
40
50
60
70
measurement 1
measurement 2
height
[m
m
]
Acetone concentration (wt-%)
Stofftransport an Einzeltropfen mit Konzentrationsprofil in der kontinuierlichen Phase
Experimental conditions
Material system
butylacetate + water + acetone
Concentration gradient
linear
declining
increasing
drop diameter
2.88 mm
3.22 mm
4.06 mm
start concentration in
continuous phase
0%
> 0%
start concentration in
dispers phase
0%
0% ‐ cont.
> cont.
TU Graz I Institute of Chemical Engineering and Environmental Technology Heidelberg, 16.03.2015Fachtagung Extraktion,
11
Linear profile: different diameters
0
1
2
3
4
5
6
7
8
0
10
20
30
40
50
60
70
80
dispers phase
2.88 mm
3.22 mm
4.06 mm
continuouse phase
linear profile
he
ig
ht (cm)
Acetone concentration (wt-%)
Stofftransport an Einzeltropfen mit Konzentrationsprofil in der kontinuierlichen Phase
Linear profile: different starting conditions
0
1
2
3
4
5
6
7
8
0
10
20
30
40
50
60
70
80
continuous phase
dispers phase
hei
ght (cm)
Acetone concentration (wt-%)
TU Graz I Institute of Chemical Engineering and Environmental Technology Heidelberg, 16.03.2015Fachtagung Extraktion,
13
Linear profile: different starting conditions
0
1
2
3
4
5
6
7
8
0
10
20
30
40
50
60
70
80
continuous phase
dispers phase
hei
ght (cm)
Acetone concentration (wt-%)
Stofftransport an Einzeltropfen mit Konzentrationsprofil in der kontinuierlichen Phase
Modelling
0,0
0,2
0,4
0,6
0,8
1,0
relevant gradient
to determine
dcon
c
en
tr
a
tion
in dro
p
le
t
y = f(r
/R)
dy*/dt = const
concentration profile
y* = const
constant concentration
y*
dimensionless drop radius r/R
y
TU Graz I Institute of Chemical Engineering and Environmental Technology Heidelberg, 16.03.2015Fachtagung Extraktion,
15
Modelling
∙
,
4 ∙
,
∙
,
∙
∙ 1
y* = k x
∙ ∙ ∆c
0
Stofftransport an Einzeltropfen mit Konzentrationsprofil in der kontinuierlichen Phase
Modelling
Constant concentration:
4
∙
4 ∙
9
Concentration Profile:
16
∙
0,0
0,2
0,4
0,6
0,8
1,0
relevanter Gradient zur
Bestimmung von
dconc
entrati
on in dr
op
le
t y
=
f(r/
R
)
dy*/dt = const
concentration profile
y* = const
constant concentration
y*dimensionless drop radius r/R
TU Graz I Institute of Chemical Engineering and Environmental Technology Heidelberg, 16.03.2015Fachtagung Extraktion,
17
Linear profile: different starting conditions
0
1
2
3
4
5
6
7
8
0
10
20
30
40
50
60
70
80
continuous phase
dispers phase
he
ig
ht
(
c
m
)
Acetone concentration (wt-%)
Stofftransport an Einzeltropfen mit Konzentrationsprofil in der kontinuierlichen Phase
Linear profile: different starting conditions
0
1
2
3
4
5
6
7
8
0
10
20
30
40
50
60
70
80
continuous phase
dispers phase
model constant concentration
model concentration profile
he
ig
ht
(cm
)
Acetone concentration (wt-%)
TU Graz I Institute of Chemical Engineering and Environmental Technology Heidelberg, 16.03.2015Fachtagung Extraktion,
19
Linear profile: different starting conditions
0
1
2
3
4
5
6
7
8
0
10
20
30
40
50
60
70
80
continuous phase
dispers phase
model constant concentration
model concentration profile
he
ig
ht
(cm
)
Acetone concentration (wt-%)
Stofftransport an Einzeltropfen mit Konzentrationsprofil in der kontinuierlichen Phase
Linear profile: different diameters
0
1
2
3
4
5
6
7
8
0
10
20
30
40
50
60
70
80
continuous phase
dispers phase (measured and model):
d = 2.88 mm
d = 3.22 mm
d = 4.06 mm
he
ight
(cm)
Acetone concentration (wt-%)
TU Graz I Institute of Chemical Engineering and Environmental Technology Heidelberg, 16.03.2015Fachtagung Extraktion,