Experimental Study on the Solid-Liquid Separation of Sugar Mud
Yanhui Chen, Xinjie Zhang and Linfeng Zhang
School of Mechanical Engineering, Guangxi University of Science and Technology, Liuzhou, China
gxut_jx@163.com, 930243857@qq.com, 838492376@qq.com
Keywords: The Characteristics of Sugar Mud, Dehydration Rate, Influencing Factors.
Abstract: In order to research the relevant dehydration properties of sugar mud deeply. The paper carry out the
compression dehydration experiment with sugar mud as the raw material which using the piston type
dehydration device of self-designed. The effect of the mass and the pressure on the dehydration rate of the
sugar mud was analysed according to the relationship between the time and the filtrate volume. Thus, the
type of the compression filter of the sugar mud was determined. Finally, the corresponding mathematical
formula was derived from the theory of one dimensional squeezing and dewatering.
1 INTRODUCTION
Biomass energy refers to some of the wastes
produced by agriculture, forestry and animal
husbandry. The conversion of solar energy into
internal energy and aggregated into organisms
mainly through photosynthesis in plants.
Theoretically, it belongs to renewable energy (Ma,
2012) (Chen, 2010). Sugar cane was one of the
sources of biomass energy. Sugar making plants use
sugar cane to process sugar. Most of the sugar was
used to produce white sugar. But a small portion of
the sugar was carried away by the by-products
produced in the sugar process. If the sugar sludge
was disposed of arbitrarily or discarded, it could
easily cause deterioration, decay and pollution. On
the other hand, it was also a serious waste of
resources. Comprehensive development of effective
utilization of the sugar mud, not only reduces the
waste of resources, the raw materials were provided
for the production of other products, the
corresponding environmental problems were solved,
and also brought some social and economic benefits.
However, the comprehensive utilization of sugar
mud were based on the dehydration and the drying.
Therefore, the study on the properties of sugar mud
dehydration has very important practical
significance.
2 EXPERIMENT EQUIPMENT
AND METHODS
The experiment device for the compression and the
dehydration of sugar mud as shown in Figure 1. It
was mainly composed of pressure bar, piston,
cylinder, fixed plate and filter panel. The filter panel
was evenly distributed with dehydration micro-pores
about 2 mm. 300 mesh nylon filter cloth was
selected as the filter medium according to the
previous experiment.
1. Pressure bar; 2. Piston; 3. Cylinder; 4. Fixed plate;
5. Filter panel; 6. Body bracket
Figure 1: The schematic diagram of experiment device.
Experiment method: Firstly, clean and dry the
beaker with sugar mud. Then weigh it and record the
mass as
1
m
. Secondly, get the sugar mud back to
the normal temperature and pour into the beaker.
And weighed and recorded as
2
m
to ensure the
mass of the sugar mud taken as the experiment.
532
Chen, Y., Zhang, X. and Zhang, L.
Experimental Study on the Solid-Liquid Separation of Sugar Mud.
In 3rd International Conference on Electromechanical Control Technology and Transportation (ICECTT 2018), pages 532-535
ISBN: 978-989-758-312-4
Copyright © 2018 by SCITEPRESS – Science and Technology Publications, Lda. All rights reserved
Finally, the 400 g, 500 g, 600g and 700g of sugar
mud gained from the weighing were poured into the
cylinder. And the dehydration experiments under the
pressure of 0.08 MPa, 0.23 MPa, 0.38 MPa, 0.53
MPa and 0.68 MPa were carried out respectively.
Meanwhile, recorded the filter time and the
corresponding amount of filtrate.
3 EXPERIMENT RESULTS AND
ANALYSIS
According to the above experiment method, the
sugar mud was compressed and dehydrated, and the
experiment data of time and filter were arranged as
shown in the Figure 2.
Figure 2: The relationship between time and filter of sugar
mud under different pressures
It can be seen that with the increase of pressure
on 400 g sugar mud, the filtrate volumes gradually
increased, when squeezing 500 g sugar mud, the
filtrate volumes first increased and then decreased,
mainly due to excessive pressure so that the medium
surface cake layer to accelerate the formation.
Resulting in increased filtration resistance, and the
dehydration rate decreased. When the pressure of
0.68 MPa in 600 g sugar mud, the filtrate volumes
increased more than 500 g, then the formation of
filter cake layer slowly. The mass increased to 700 g,
the four curves approximate coincidence. Increasing
the pressure has little effect, and only when the
pressure was large enough to obtain more the filtrate
volumes. However, there was a certain limit to
dewatering and dehydration.
3.1 Filtration Resistance and
Compressibility Factor
The filtration resistance shows the resistance of the
unit mass of material in unit filtration area (Wan,
2007). The data was obtained by the relationship of
vt /
and
v
in Cartesian coordinates. The constant
pressure filtration coefficient was obtained by linear
fitting, and the specific filtration resistance was
calculated by formula as shown in Table 1.
sK
msP
av
)1(2
α
(1)
In the Equation (1):
v
- the filtrate volume of
the unit filtration area;
K
- the filtration
coefficient of constant pressure; P - pressure
difference，
p
a
;
m
- wet dry ratio of filter cake;
s
- the concentration of solid mass;
- the
density of filtrate，
3
g/cm ;
- the viscosity of
filtrate，
s
p
a
；
Table 1: The filtration resistance of sugar mud under
different pressures
Filtratio
n
resistan
ce
0.23
MPa
0.38
MPa
0.53
MPa
0.68
MPa
400 g 4.20*10
15
9.99*10
15
6.48*10
15
——
500 g 4.41*10
15
6.99*10
15
8.95*10
15
2.28*10
15
600 g 4.50*10
15
5.80*10
15
8.44*10
15
1.26*10
15
700 g 2.87*10
15
4.85*10
15
1.99*10
15
8.55*10
15
The filtration ratio of the sugar mud filter cake
was in the order of about
1615
10~10
, and it was a
kind of difficult to filter materials. Besides, it was
mainly due to the existence of sugar substance,
which makes the solid particles of sugar mud exist
the larger force.
Compressibility coefficient that the material
under the action of external force volume changes
easily, according to the size of the compressibility
factor was divided into high-compression, medium-
compression, low-compression and
incompressibility of materials. According to the
relationship between the pressure and the average
filter, the logarithmic was obtained (Rushton, 2005).
Pn
av
logloglog
0
(2)
Experimental Study on the Solid-Liquid Separation of Sugar Mud
533
In the Equation (2), the relationship between
av
log and
Plog
was obtained in Cartesian
coordinates, and the compressibility coefficient was
obtained by straight line fitting as shown in Table 2.
Table 2: The compressibility coefficient of different
masses mud under different pressures
Mass/
g
400 500 600 700
Compressibility
factor
/
n
1.48 1.37 0.93 0.58
The compression coefficient of the sugar mud
was more than 0.5, which belongs to the high-
compression shrinkage material. Therefore, the
sugar mud was a kind of material which was easy to
be compressed but difficult to be filtered. So, the
pretreatment may be appropriately performed in
order to improve the dehydration rate of sugar mud.
4 THE MATHEMATICAL
RELATION BETWEEN THE
DEHYDRATION RATE OF
SUGAR MUD WITH THE MASS
AND THE PRESSURE
The Equation of Kozeny-Carman (Zhao, 2006)
based on the Porseuille theory not only describes the
microstructure of the filter cake, but also reveals the
inherent relationships among many factors in the
filtration process . The mathematical equation as
k
L
P
SK
u
2
0
2
1
3
)1(
(3)
In the Equation (3):
- porosity;
- average
linear velocity of liquid filtration,
sm/
;
1
K - the
constant of Kozeny, generally taken as 5;
0
S -
particle specific surface area,
32
/ mm
;
k
L - the
thickness of the cake layer,
m
;
In a simplified model of dehydration rate, Zhang,
J. Z.
(Zhang, 2015) assumed that the sugar mud was
saturated material and that the solid particles were
evenly distributed. The liquid phase was forced
during the compression, ignoring the solid phase and
the sugar mud was incompressible cake under high
temperature. According to the experiment done in
this paper showed that sugar mud was a highly
compressible filter cake at room temperature.
Let the filter area of
A
, the volume of sugar mud
dehydration
V
, the dehydration time t, the filtration
rate could be expressed as
A
dt
dV
u
(4)
According to the solid phase in the filtration
process remains the same principle, it was known
that
)1()1(
00
VV
(5)
In the Equation (5):
0
- the initial porosity;
0
V -
the initial volume of sugar mud,
3
m
;
A differential equation with above three
simultaneous equations to obtain porosity with the
variation of time.
k
L
VSK
PA
dt
d
3
00
2
01
)1(
(6)
The porosity of the constant pressure filtration
stage could be expressed as (Chen, 1993)
kS
AL
M
1
(7)
The relationship between the mass and the
volume of sugar mud in the dry state as
)1(
00
AL
M
V
s
d
d
(8)
The Equation (7) and Equation (8) were
substituted the Equation (6), and got
3
2
01
22
)1(
MmSK
AP
dt
d
d
s
(9)
In the Equation (9):
M
- the mass of sugar mud,
kg
;
d
m - the mass of dry sugar mud,
kg
;
d
V - the
volume of dry sugar mud,
3
m
;
s
- the density of
the dry sugar mud,
3
/ cmkg ;
ICECTT 2018 - 3rd International Conference on Electromechanical Control Technology and Transportation
534
The variables were solved separately.
t
MmSK
AP
d
s
2
01
22
2
2
0
2
2
0
0
0
0
0
2
1
1
ln
(10)
Saturated sugar mud porosity ratio was equal to
the ratio of water content, the rate of dehydration
Mm
出
, then the moisture content was
1
1
1
1
1
0
0
(11)
In the Equation (11):
- the moisture content;
0
- the initial moisture content;
出
m - the
dehydration mass of sugar mud;
After the simplification, the relationship between
the dehydration rate of sugar mud and time under
different mass and pressure was obtained
t
MmSK
AP
d
s
2
01
22
2
0
2
2
00
)1()(2
(12)
5 CONCLUSIONS
(1) In the pressure range of this experiment, the
average filtration ratio of sugar mud filter cake was
in the order of
1615
10~10
. It was difficult to filter
materials. And it was mainly due to the existence of
sugar substance, which makes the solid particles of
sugar mud exist the larger force.
(2)The coefficient of the compressibility of the
sugar mud was more than 0.5, which belongs to the
high-pressure shrinkage material.
(3) On the basis of reasonable assumptions, the
sugar mud was determined as a high compression
material. And the relationship between the
dehydration rate of the sugar mud and the change of
time under different mass and pressure was deduced.
ACKNOWLEDGEMENTS
This work is supported by Guangxi Science and
Technology Development Program Funded Projects:
The construction of the comprehensive experiment
platform about earthmoving machinery operation
process (No. GuiKe 1598021-2).
REFERENCES
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Wan, Y. Q., 2007. Study on Sludge Filter Dewatering
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Rushton, A., Ward, A. S., Holdich, R. G., 2005. Solid-
liquid two-phase filtration and separation technology.
Chemical Industry Press.
Zhao, Y., 2006. Study on the Microstructure of the Filter
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