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2011 International Conference on Alternative Energy in Developing Countries and Emerging Economies
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Fig.6. Effect of drying air temperature and specific air flow rate on
specific energy consumption and drying time for two-stage drying;
initial moisture content of 48% dry-basis, final moisture content of 0.5%
dry-basis, drying temperature of 120 to 140 q C and bed depth of 0.30 m.
Fig.7. Effect of fraction of air recycled on specific energy consumption
and drying time at various drying air temperature; initial skim rubber
weight of 16.74 kg, initial moisture content of 48% dry-basis, and final
moisture content of 0.5% dry-basis, ambient temperature of 30 qC.
D. Quality of dried skim block rubber
Determine the quality of skim block rubber; the dried
samples were analyzed following the STR 20 method.
However, the visual observation can also be used for
characterizing dried skim rubber because of its color
change and uniformity of sample. The results showed that
the qualities of the dried skim rubber shown in Table II
satisfied all standard criteria. It was found that the dry
skim rubber obtained from all experiment passed the
standard tests. In addition, it was found that the quality of
skim rubber had no significant effect on difference drying
condition of the sample (p 0.05).
TABLE II
CHEMICAL QUALITY TESTING OF SKIM BLOCK RUBBER
Experiment
No.
Dirt
(%)
Ash
(%)
V.M.,
(%)
N2
(%) Po PRI
STR 20 d 0.16 d0.80 d 0.80 d0.60 t30.0 t40.0
1 0.025 0.34 0.40 0.24 44.5 70.0
2 0.040 0.37 0.38 0.27 43.5 64.0
3 0.037 0.33 0.43 0.28 48.0 67.0
4 0.028 0.32 0.39 0.31 42.0 64.0
5 0.020 0.28 0.52 0.25 43.5 64.0
6 0.016 0.54 1.34 2.01 31.0 40.0
7 0.015 0.50 1.45 1.99 31.0 40.8
8 0.013 0.46 0.90 2.00 30.0 41.4
9 0.036 0.43 1.29 1.88 40.0 75.0
10 0.015 0.43 1.08 1.79 39.0 66.7
Note: Standard STR 20 block rubber must be within limited as
followed: % Dirtd0.16%; ASHd0.80%; VMd 0.80%;
N 2d0.60%; PO>30%; PRI>40 %.
Dirt = dirt material or impurity inside block rubber;
VM = volatile matter;
PO = initial plasticity; PRI = plasticity ratio index
IV. CONCLUSIONS
The mathematical model of skim rubber drying
predicts fairly the drying rate and specific energy
consumption. The specific air flow rate, drying air
temperature and fraction of air recycle affect on specific
energy consumption.
ACKNOWLEDGMENT
The authors would like to thank the Graduate Studies
Grant, Department of Chemical Engineering, Faculty of
Engineering; Department of Physics, Faculty of Science,
Graduate school under Prince of Songkla University for
their financial support and comfort research area for this
work.
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Aregba, A. W., Sebastian, P., & Nadeau, J. P. (2006).
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ASABE Standards. (1988). S352.2: Moisture
measurement--Unground grain and seeds ASAE.
Michigan, USA: St. Joseph.
ASABE Standards. (2007). D245.6: Moisture
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0
50
100
150
200
250
300
10
20
30
40
50
60
0.00 0.05 0.10 0.15
Drying time (min)
specific energy consumption(MJ/kg water evaporated)
Specific air flow rate (kg dry air/s-kg dry rubber)
SEC at 100°C SEC at 120°C
SEC at 130°C SEC at 140°C
DT at 100°C DT at 120°C
DT at 130°C DT at 140°C
50
100
150
200
250
10
20
30
40
50
60
0 20 40 60 80 100
Drying time (min)
specific energy consumption(MJ/kg water evaporated)Fraction of air recycled (%)
SEC at = 100°C SEC at = 120°C
SEC at = 130°C SEC at = 140°C
DT at = 100°C DT at = 120°C
DT at = 130°C DT at = 140°C