s.y. adzaklo,* c.p.k. dagadu, i.i. mumuni, p.s. adu, h.a. affum, … · 2017. 4. 27. ·...
TRANSCRIPT
S.Y. Adzaklo,* C.P.K. Dagadu, I.I. Mumuni, P.S. Adu, H.A. Affum, G.K. Appiah, A.
Coleman
INTRODUCTION
The main aim of industrial mixing is to provide mass transfer of material to promote better contact between reactor contents in order to obtain the required product quality in the shortest possible time (Kuncewicz et al., 2005).
However, many industrial mixing operations are either inefficient or more than enough, mainly as a result of improper reactor design.
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Introduction This is due to lack of understanding of the mixing
process which could be attributed to the complex nature of impeller-induced flows in stirred vessels (Delvigne et al., 2005).
This leads to poor product quality and overconsumption of energy that eventually results in high production costs
Therefore, there is the need for in-depth studies of mixing operations to determine the performance of mixing vessels.
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Introduction A good understanding of mixing operations in
stirred vessels will enhance optimal design and help modify existing processes in order to minimize capital and running costs (Dagadu et al., 2015).
This work was done to investigate the effect of impeller type on mixing and determine the fluid dynamics of the material in the vessels.
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EXPERIMENTAL SYSTEM
ICARST 2017, VIENNA, AUSTRIA, 24-28TH APRIL 2017
Fig. 4: axial impeller (b) radial impeller
(a) (b)
EXPERIMENTAL SYSTEM
ICARST 2017, VIENNA, AUSTRIA, 24-28TH APRIL 2017
Fig. 1 Experimental set up
EXPERIMENTAL SYSTEM
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Experimental
Parameters
TK 1
(1 axial
impellers)
Tank2
(2 axial
impeller)
Tank3
(2 radial
impeller)
Tank 4
(no
impeller)
Tank height (cm) 61.0 61.0 61.0 61.0
Free board height
(cm)
10.0 10.0 10.0 10.0
Tank diameter
(cm)
38.2 38.2 38.2 38.2
Material volume
(lit)
58.4 58.4 58.4 58.4
Flow rate
(lit/min)
10 10 10 10
PROCEDURE
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PROCEDURE
Mean Residence Time (MRT) and the variance were calculated by the method of moments.
The fluid dynamics were obtained by modeling using
DTSpro and
RTD Software
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RESULTS AND DISCUSSIONS
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Model
Parameters
TK 1
(1 axial
impellers)
PMSR
Tank2
(2 axial
impeller)
PMSE
Tank3
(2 radial
impeller)
PMSE
Tank 4
(no
impeller)
PMSE
Cum. tact(min) Tau 1 = 5 9.5 17.2 25.5
tm(min) J1 = 2.1 3.8 11.4 1
J Tau2 = 1 2.8 3.2 3.7
k J2 = 1, =
0.13
0.36 0.15 0.1
MRT Per tank
(min)
5.7 7.3 6.9 5.3
Variance , 2
Per tank (min2)
40.4 80.7 66.3 27.6
RESULTS AND DISCUSSIONS
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Experimental
Parameters
cont’d
TK 1
(1 axial
impellers)
Tank2
(2 axial
impeller)
Tank3
(2 radial
impeller)
Tank 4
(no
impeller)
Theoretical MRT
(min)
5.8 5.8 5.8 5.8
Exp. MRT per
tank (min)
5.3 7.5 7.1 5.1
Exp. Variance per
tank, 2 (min2)
42.4 86.3 57.7 26.6
RESULTS AND DISCUSSIONS
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0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0 20 40 60 80
E(t
) (
min
time (min)
Fig. 7 Tank 1 (1 axial impeller)
EXPERIMENTAL
PMSR MODEL
RESULTS AND DISCUSSIONS
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0
0.01
0.02
0.03
0.04
0.05
0.06
0 20 40 60 80
E(t
) (m
in-1
)
Time (min)
Fig. 8 Tank 2 (2 axial impellers)
EXPERIMENTALPMSE MODEL
RESULTS AND DISCUSSIONS
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0
0.005
0.01
0.015
0.02
0.025
0.03
0.035
0.04
0 20 40 60 80
E(t
) (m
in-1
)
Time (min)
Fig. 9 Tank 3 (2 radial impellers)
EXPERIMENTAL
PMSE MODEL
RESULTS AND DISCUSSIONS
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0
0.005
0.01
0.015
0.02
0.025
0.03
0.035
0 20 40 60 80 100
E(t
) (m
in-1
)
Time (min)
Fig. 10 Tank 4 (No impeller)
EXPERIMENTAL
PMSE MODEL
CONCLUSION
The extent of material mixing in the tanks were inferred from the variances
Tank 2 (with 2 axial impellers) gave the highest variance as shown above and hence indicating a better mixing than the other tanks
The next is tank 3 (with two radial impellers)
Thank 4 gave the poorest mixing. This is expected since this tank has neither impellers nor baffles which aid in material mixing
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THANK YOU FOR YOUR ATTENTION
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