hazim-lab 2
TRANSCRIPT
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UNIVERSITI TEKNOLOGI MARA
FAKULTI KEJURUTERAAN KIMIACHEMICAL ENGINEERING LABORATORY
(CHE574)
NAME : MOHD HAZIM BIN ELIAS
STUDENT NO. : 2004624588
EXPERIMENT : DEEP BED FILTER
DATEPERFORMED
: JANUARY 2006
SEMESTER : DECEMBER 2005 APRIL 2006
PROGRAMME /CODE
: Bachelor of Engineering (Hons.) in ChemicalEngineering/ EH220
Remarks:
Checked by: Rechecked by:Cik Siti Ida Farida bte Abd Razak
ABSTRACT / SUMMARY
No. Title Allocated marks % Marks %1 Abstract/Summary 5
2 Introduction 53 Aims/Objectives 54 Theory 55 Procedures 36 Apparatus 57 Results 208 Calculations 109 Discussions 20
10 Conclusions 1011 Recommendations 512 References 513 Appendices 2
TOTAL 100
PK.FKK.PPM.MANUAL MAKMAL CHE574
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This particular experiment is about separating solid particle from suspension
in liquid. The experiments were conduction using the deep bed filtration apparatus.
This equipment allows particles penetrated into the interstices of the filter bed where
then they are trapped following impingement on the surfaces of the material of the
bed.
The very fine particles of solids are removed by mechanical action but the
particles finally adhere as a result of surface electrostatic forces or adsorption. The
objective of this experiment is to determine the pressure drop across the bed, the
nature of flow in filter bed and to determine the performance of the bed.
Three theory is used to calculate the result, Darcy-Weisbach formulation,
friction factor estimation and pressure drop in porous bed. The result from the
experiment is calculated and graph is plotted.
INTRODUCTION
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Filtration is a physical operation that used largely in industry to separate solid
particle from suspensions in liquid. In a filtration system, porous layer is used where
only liquid is allowed to follow through them.
There are many reasons on why filtration systems are used in industries. They
are:
i. To separate solid particles that has commercial value from liquid or gas.
ii. To separate solid waste from valuable liquid, such as solid suspension from
oil.
iii. To separate both solid and liquid when both have commercial value.
iv. To separate both solid and liquid even if both does not have any commercial
value such as if both is harmful material and has to be disposed accordingly.
Deep bed filter allows particles penetrated into the interstices of the filter bed where
then they are trapped following impingement on the surfaces of the material of the
bed. The very fine particles of solids are removed by mechanical action but the
particles finally adhere as a result of surface electrostatic forces or adsorption.
AIMS / OBJECTIVES
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To determine the pressure drop across the bed
To determine the nature of flow in filter bed
To determine the performance of the bed
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THEORY
Darcy Weisbach Formulation
The formula involves the study of straight pipe in which an incompressible
fluid flows in it. Consider the following functional relationship:
P = f (v, , D, , L, )
Where
P Pressure drop between two points
v Velocity of fluid
Density of fluid
D Pipe diameter
Viscosity of fluid
L length of pipe
Roughness of pipe wall
From above, seven magnitudes are expressed as a function of three basic
dimensions i.e L, M and T, which then form 4 dimensional parameters. By repeating
v, , D and with the addition of other magnitudes, the parameters are:
1 = P 2 = v D 3 = 4 = L
v 2 D D
Thus, we can also express the relationship as dimensional function:
P / v 2 = f (vD / , / D, L /D)
Consider P = gh f , where h f is the loss of total load between two sections of the pipe,
then
hf = (L / D) (v 2 / 2g)
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where is the friction factor from Moody diagram
Friction Factor, Estimation.
Nikuradse and Moody determined the friction factor, experimentally where
Nikuradse used pipes with artificial roughness whilst Moody used commercial pipes
with roughness is the characteristic of the pipe. The results obtained by Moody are
shown in Figure 2 .
From the diagram, following are the parameters that can be considered:
a. For Re < 2000, in the fluid flow, friction factor only dependence on Reynolds
number but not wall roughness, where = 64 / Re
b. The transition region of Reynolds number gives the friction factor,
depending simultaneously on the viscous effects and on the roughness of the
pipe and hence = f (Re, / D)
c. For sufficiently high Re number, the viscous effect do not cause effect and the
friction factor, only depend on the roughness of the wall, where = f ( / D)
Pressure Drop in Porous Beds.
The pressure drop caused by the contact between particles and the media
accompanying the flow of fluid can be calculated using the following general
procedure:
a. Reynolds number of the fluid flow in the packed bed, Re based on the
diameter of the particles, d p and the approach velocity of the fluid to the bed,
va is affected by the correction coefficient, F Re (Figure 3 ) where:
Re = (v ad p / ) F Re
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Where F Re = f (, ) porosity / voidage of the bed
sphericity of particles
b. The friction factor, ( Figure 4 ) depends on Reynolds number, Re, so
= f (Re)
c. The pressure drop in the porous drop gives similar expression to the pressure
drop in pipes but however, it is affected by a correction coefficient, F f (Figure
5):
H f = (L / d p) (v a2 / 2g) (F f )
Where F f = f (, )
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PROCEDURES
Preliminary Experiment
Tank D1 and D2 was filled with clean water. Pump switched on. Valve V 2 and
V2, V 5 and V 7 opened, and valve V 4 and V 6 closed. Valve V 3 was adjusted to
establish flow and the water allowed circulating in 2 to 3 minutes. If there was bubble
trapped in the water manometer column, purging method was applied by increasing
water height in the manometer column until the bubbles disappeared. Total height of
bed measured.
Experiment 1: Lost of Load of a Porous Bed
Valve V 3 adjusted, and if necessary, valve V 2 closed to obtain the difference of
pressure of 1000 mm between tube 1 and 30. The readings from tube 1 to tube 30
were noted. The experiment repeated to get the 10 different flows covering the range
of flowmeter. Before stopping the pump, valve V 2 fully opened and valve V 3 fully
closed to avoid entrance of air to the circuit.
Experiment 2: Loss of Load h f in Function of Depth and Time
Solid-suspension liquid was prepared in tank D2 (about 100 g of flour). The
clarity of the liquid was test using turbidimeter. Valve V 1 and V 2 opened, and valve
V3 closed and pump started. Valve V 3 opened until flow rate, Q = 60 L / hr reached.
When the cloudy suspension reached the packed bed, the timing started and the time
registered. Verify that the flow remains constant and if necessary, the flow adjusted
using valve V 3. The reading repeated in every 30 minutes. The samples were collected
at the 1 st, 2 nd, 6 th, 10 th, 15 th, 20 th, 25 th and 30 th tubes. The turbidity of each samples
measured using turbidimeter. The results recorded. Besides that, the reading of the
tubes also recorded. The length of the column from the base to the respective tappings
measured. The pump stopped when the experiment finished.
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APPARATUS
Deep bed filter
Turbidimeter Stopped watch
Beaker for making the solution of flour
Spatula for stirring the solution of flour
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RESULTS
Experiment 1: Lost of Load of a Porous Bed
Flow Rate, Q (L / hr) h 1 h30 hf = h 1 - h 30 10 572 520 52
20 592 504 8830 612 490 12240 642 468 17450 662 438 22460 682 408 27470 708 380 32880 738 346 39290 764 304 460
100 802 268 534
Table 1: Data for experiment lost of load in a porous bed
Flow Rate, Q (L /hr) Q (m 3 / s) v a (m / s) Re' ' H f (m)10 2.778E-06 3.537E-04 17.684 4.0 0.065720 5.556E-06 7.074E-04 35.368 1.7 0.111630 8.333E-06 1.061E-03 53.052 1.2 0.177340 1.111E-05 1.415E-03 70.735 0.8 0.210150 1.389E-05 1.768E-03 88.419 0.7 0.287360 1.667E-05 2.122E-03 106.103 0.6 0.3546
70 1.944E-05 2.476E-03 123.787 0.5 0.402280 2.222E-05 2.829E-03 141.471 0.4 0.420390 2.500E-05 3.183E-03 159.155 0.4 0.5319
100 2.778E-05 3.537E-03 176.838 0.3 0.5582
Table 2: Table of calculation for theoretical head loss
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Graph of Head Loss versus Flowrate
0
0.1
0.2
0.30.4
0.5
0.6
2 . 7
7 8 E
- 0 6
5 . 5
5 6 E
- 0 6
8 . 3
3 3 E
- 0 6
1 . 1
1 1 E
- 0 5
1 . 3
8 9 E
- 0 5
1 . 6
6 7 E
- 0 5
1 . 9
4 4 E
- 0 5
2 . 2
2 2 E
- 0 5
2 . 5
0 0 E
- 0 5
2 . 7
7 8 E
- 0 5
Flowrate
H e a
d L o s s
experimental value
theoretical value
Experiment 2: Loss of Load h f in Function of Depth and Time
number of L (mm) Lapsed time (minutes)
tube 30 60 90
hf ' turbidity h f ' turbidity h f ' turbidity1 90 670 42.8 690 50.5 694 38.12 120 656 45.6 680 47.1 682 37.36 220 636 48.1 648 40.7 650 32.7
10 320 608 47.6 620 34.8 622 30.115 440 570 45.1 580 34.6 574 33.820 570 542 39.6 540 33.1 538 29.125 690 506 33.3 498 31.2 500 28.230 1020 420 32.4 394 30.5 408 25.5
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Table 3: Table of loss of load and turbidity in function of depth and time
Graph Length of column vs Pressure drop
0
200
400
600
800
1000
1200
0.00 2000.00 4000.00 6000. 00 8000.00
pressure drop
l e n g
t h o
f c o
l u m n
30 min
60 min
90 min
Graph Turbidity versus Length of Column
0
10
20
30
40
50
60
0 200 400 600 800 1000 1200
Length of Column
T u r b
i d i t y 30 min
60 min
90 min
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CALCULATIONS
Data:
Internal diameter of the column, D: 100 mm
Density of sand, p = 2650 kg / m 3
Sphericity of sand, = 0.8
Diameter of sand, d p = 1 mm
Density of water, f = 1000 kg / m 3
Viscosity of water, f = 0.001 kg / ms
Length, L = 1030 mm
Mass of bulk, m = 8.7 kg
Voidage of bed = 0.4
Voidage of the bed, bed = 1 ( b / p)
0.4 = 1 __ b kg / m 3
2650 kg / m 3
b = 1590 kg/m 3
From the figure 3 , the value of F Re = 50
From the figure 5 , the value of F f = 2500
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Sample of Calculation
Consider the first reading in experiment 1
Q = A . v a
va = Q / A
= 10 L 1 hr 1E-3 m 3 1_______
hr 3600 s 1 L 7.854 x 10 -3 m 2
= 3.537 x 10 -4 m / s
Re = (v ad p / ) F Re
= 1000 kg m -3 x 3.537 x 10 -4 m s -1 x 1E-3 m x 50
0.001 kg m -1 s-1
= 17.684
From figure 4 , for first reading = 4.0
From figure 5 , F f = 2500
H f = (L / d p) (v a2 / 2g) (F f )
= 9 x 1030E-3 m (3.537 x 10 -4 m s -1)2 (2500)
1E-3 (2) (9.81 m s -2)
= 0.0657 m
P = gh f
=1000 kg/m 3 x 9.81 m s -2 x 0.67 m
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DISSCUSSIONS
The separation of solids from a suspension in a liquid by means of a porous
medium or screen which retains the solid and allows the liquid to pass is termed
filtration. In general, the pores of the medium will be larger than the particles which
are to be removed, and the filter will work efficiently only after an initial deposit has
been trapped in the medium. The most important factors on which the rate of filtration
depends be are the pressure drop from the feed to the far side of the filter medium, the
area of the filtering surface, the viscosity of the filtrate, the resistance of the filter
cake, and the resistance of the filter medium and initial layers of cake.
For first experiment the graph that been plot from the experiment result and
theoretical result shows the similarity in the graph pattern. Its show that the particular
theory is suite for that particular experiment condition. For second experiment the
pressure drop is decreasing when the column height increase. However the pressure
drop value is similar for different time taken 30 minute, 60 minute and 90 minute.
This condition happen because the changes in concentration of solid suspend in liquid
is not affecting the pressure drop.
The value of turbidity that determine from the turbid meter is non consistent.
This is because the sand particle that used in the filter bed is not equal. However the
turbidity value is still decreasing at the maximum height of the column.
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CONCLUSIONS
1. The bed voidage is 0.4 and the bulk density is 1590 kg/m 3
2. The theoretical head loss h f of the porous bed is
Flow Rate, Q (L / hr) Hf (m)10 0.065720 0.111630 0.177340 0.210150 0.287360 0.354670 0.4022
80 0.420390 0.5319
100 0.5582
3. The data that gained from the experiment is similar to the data that obtained
from theoretical calculation using the formulation. Its show that the
experimental value is valid.
4. The nature of the flow is analyzed based on the Reynolds number
Q (m 3 / s) Re' Nature of flow
2.778E-06 17.684 laminar
5.556E-06 35.368 laminar
8.333E-06 53.052 laminar
1.111E-05 70.735 laminar
1.389E-05 88.419 laminar
1.667E-05 106.103 laminar
1.944E-05 123.787 laminar
2.222E-05 141.471laminar
2.500E-05 159.155 laminar
2.778E-05 176.838 laminar
RECOMMENDATIONS
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1. Mix the liquid with colored dye in order to differentiate the liquid in the
manometer tube with the wall scale. This is important in order to get the
accurate reading
2. All bubble must be vanish from the manometer tube by increasing water level
in manometer to the maximum value.
3. Take the average reading because the water level in the manometer tube is not
stable in order to prevent from parallax error.
REFERENCES
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Rhodes, M; Introduction to Particle Technology ; John Wiley
Coulson J. M and Richardson J. F; Chemical Engineering Volume 2 ;Butterworth Heinemann
McCabe, Smith, Harriott; Unit Operation of Chemical Engineering ; McGraw
Hill
APPENDICES
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