Filtration Experiment

7/24/2019 Filtration Experiment

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Filtration experiment

Introduction

An investigation was carried out with the objective to determine the medium andcake resistance during a constant fltration rate period. Filtration is a mechanicalseparation process used to separate a solid rom a uid by placing a fltermedium which only allows the uid (fltrate) to pass through while retaining thesolid. his is an important process used in many applications in the oil! gas! oodand beverage! and pharmaceutical industries. he aim o fltration is to either!remove contaminates rom a li"uid! or or the collection o suspended solidparticles rom the li"uid that may be valuable or another use. his could help#

$revent damage that can be caused by the contamination o a given

li"uid! either to people! machinery! or the environment.

$roduce a higher yield o the desired end product

%reate a more pure product which in turn is more valuable

&ecovery o material or use in other applications

'ower operating costs


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Figure 1: How a plate and frame lter works ()

Figure 2: Weighing scale !omputer "#$12 ltration unit (left to right)

A plate and rame flter press unit shown in Figure is used in this eperiment.his type o flter consists oplates and rames arrangedalternately and supported on apair o rails. he plates have aribbed surace. he hollow rameis separated rom the plate by theflter medium! and the press isclosed either by means o a handscrew or hydraulically! using theminimum pressure in order toreduce wear on medium. Achamber is thereore ormedbetween each pair o successiveplates. A precoat is usually usedto improve fltration because itincreases the resistance o the

medium which increases pressuredrop. he slurry is introducedthrough a port in each rame and

the fltrate passes through the cloth on each side so that two cakes are ormedsimultaneously in each chamber. his creates a pressure drop due to the cakeresistance. he characteristic o a plate and rame flter unit can be describedusing the *arcy e"uation! shown below. he e"uation just shows that fltratione+ciency is depended on uid velocity! uid viscosity and resistances in themedium. hese all have an e,ect due to the pressure di,erences they cause.*erivations rom this e"uation (see appendi A) will be used to work out themedium resistance and the cake resistance.

%pparatus

he ollowing apparatus are re"uired or this eperiment#

-$/ Filtration -nit with $late 0 Frame Filter

%omputer with -$/ sotware installed

%alcium %arbonate

$re1coat

*eionised water

2eighing scale

litre measuring cylinder

/ /33ml 4eakers


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hree way

ure &: 'imple process ow diagram more detailed diagram featuring the sensors and isolation ales in the *rief


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drain

Ha+ard anal,sis

he three chemicals used during the eperiment are deionised water! calcium

carbonate and precoat. 3' o water is used during the eperiment as a

minimum and this is continuously collected rom a di,erent room. his means

there is a very high risk o spillage which could possibly lead to trips and alls. o

reduce this risk! ensure that you don5t carry too much water on each trip rom

the other room. wo people can also be assigned to this task to help with

opening doors and carrying the weight. 6reat care should also be taken when

transerring the water into the eed tank to reduce the risk o spillage. here is

also a risk o spilling the water on the various electronic e"uipment such as the

computer so move the water around with caution to prevent electrocution.

%alcium carbonate can cause irritation to eyes so immediately and thoroughly

ush eyes out with large amounts o water i eposure occurs. 7 ingested! rinse

the mouth cavity with water and induce vomiting. 7 inhaled move the victim to

resh air then instruct them to blow their nose. he composition o the pre1coat is

unknown but do not inhale or get it anywhere near your eyes due to its

powdered nature.

$ersonal $rotection 8"uipment (gloves! lab coat and goggles) must be worn at all

during the eperiment. *o not leave the eperiment unattended and do not

consume ood or drink in the lab.

$rocedure

. 2eigh out 9 grams o precoat on the balance then add it to : litres o

water to make a 3.;< (w=v) precoat solution.

/. >tart up the eed tank stirrer to create a homogenous eed solution.


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:. >et valve ? to a position that allows the fltrate to return to the eed tank.

@. >tart pumping! Adjust the eed ow rate to B ' hCD using the control panel

taking the reading o, the computer

B. 4leed any air rom the flter plates.

;. 'et the water cycle through or 31B minutes! until the water is relatively

clear.

. 2eigh out B3 grams o %a%:! add to ' o deionised water and then add

the %a%:solution to the eed tank or a total 3'. he fnal concentration

o %a%:in the eed tank should be 3.B< (w=v).

9. >et valve ? to a position that allows the fltrate to go to the collection

vessel.

?. >tart pumping! setting the eed ow rate o @B ' hCD .

3.7mmediately begin data login. ($ressure was also recorded manually

taking a reading rom the control panel just in case any technical

di+culties occurred).

.%ontinue the fltration until the li"uid level in the tank becomes low (E:')

/.he pump should switch o, automatically but switch o, the eed tank

stirrer! and stop data logging.

:.Add B' deionised water to the eed tank to clean the pump.

@.urn on the eed tank and pump! leave ? to drain.

B.*ismantle! clean and reassemble the flter plates (do not touch the flter

medium when cleaning to avoid damaging it)

-esults

>ee appendi (*) or the table with the data.

>ee appendi (A) or the graphical presentation o data and calculations

Filter medium resistance (&) G 1.;@: 3? m1

%ake resistance (&c) G .9B@ 33m1

.iscussion

he results rom the investigations showed that the medium resistance is 1.;@:

3? m1 and the cake resistance was .9B@ 33 m1. As fltration happens

the fltrate enters through a porous medium and the solids in the fltrate remain


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on the surace start to build up a cake. ver time! there is an increase o

resistance across the cake. *arcy5s law or a constant uid viscosity where k

(permeability o the medium)! A (fltration area) and ' (thickness o the flter bed)

are constant is# =t H I$. his shows that as iltration proceeds! change in

pressure increases. his pressure change is caused by the cake and the medium

resistance! thereore by using *arcy5s e"uation we can fnd values or & and &c.

he value or the cake resistance (&c) is very close to a value ound in source

which 7s .9/ 33 m1. his suggests that there is a percentage error o .9; (/33B). $rinciples o 7ndustrial Filtration. ord# 8lsevier

'td. /:1/?./. %entre o *isease %ontrol. (??B). ccupational >aety and Jealth 6uidelines or

%alcium %arbonate. Available# http#==www.cdc.gov=niosh=docs=91/:=pds=33?3.pd.

'ast accessed /=3:=/3@:. :. homas 8. >ulpiLio. (???). A*AO%8> 7O F7'8& A7* AO* $&8%A F7'&A7O

8%JO'6P. $resentation at the American Filtration 0 >eparations >ociety Annual

echnical %onerence. ()! 1B.@. @. 'ook -p able or specifc resistance and cake concentration (/3:) 'ook -p able

or specifc resistance and cake concentration! Available at# http#==www.fltration1and1separation.com=flter1table.htm(Accessed# /=3:=@).
http://www.cdc.gov/niosh/docs/81-123/pdfs/0090.pdfhttp://www.filtration-and-separation.com/filter-table.htmhttp://www.filtration-and-separation.com/filter-table.htmhttp://www.filtration-and-separation.com/filter-table.htmhttp://www.filtration-and-separation.com/filter-table.htmhttp://www.cdc.gov/niosh/docs/81-123/pdfs/0090.pdf


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/omenclature

$ G change in pressure

' h1G litres per hour

m:G metres cubed

Kg G kilograms

G fltrate viscosity

& G medium resistance

G specifc cake resistance

c G mass concentration o solids

sec G seconds

s G second

&cG cake resistance

v G fltrate velocity

2 G mass o cake deposit per unit area

A G fltration area

Q G volumetric ow rate o fltrate

Appendi A# %alculations

5

Assuming that an impressible cake is ormed


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3 (33 /33 :33 @33 B33 ;33 A33 933 ?33 (3333.33

3.3/

3.3@

3.3;

3.39

3.(3

3.(/

0raph showing pressure change against time

1ime (s)

$ressure change (*ar)

!hart 1: 0raph showing pressure change against time

%hart is a plot oPagainst time is or the e"uationP=av2+bv

he gradient (av/)# dy/dx=(0.11-0.01)/(890-10) =0.000114 bar s-

1105=11.4 Pa s-1

he y1intercept gives a value or bv# 13.33@; barG1@;3 $a

he total fltration area is given as# A G 0.023 m2

he fltrate viscosity is assumed to be the same as that o water at /3(room temperature) because the amount o %a%:or pre1coat present in

the fltrate is negligible #=8.9310-4Pa s

otal volume !=10 "=0.01 m3

he concentration o %a%:in the eed tank is 3.B< (w=v). For a 3.3 m:!

3.3B kg o %a%: is needed. #=0.05/ 0.01=5 $% m-3

he volumetric ow rate o the fltrate# &=45.3 " 'r-1/(300 1000)

=1.25810-5m3 s-1


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!ake resistance (-c)

av2= 11.4 Pa s-1

v=&/! thereore 11.4 Pa s-1=a(&2/2)

*a=11.4 Pa s-1(2/&2)=11.4 Pa s-1(0.023 m2)2(1.25810-5 m3 s-1)2

a=#=3810515. % s-1m-3

*=a#=3810515. % s-1m-38.9310-4Pa s 5 $% m-3=8528092 m %-1

,#= and =#!/#

=#!/=(5 $% m-30.01 m3)/0.023 m2=2.14 % m-2

*,#==8528092 m %-12.14 % m-2

-c 13456 x 1717 m81

9edium resistance (-)

bv=-40 Pa

And v=&/! *bv=b&/

b=-40Pa/&=(-40 Pa0.023 m)/21.25810-5m3s-1=-84101.488 Pa m-1s-1

b=,!

*,=b/=-84101.488 Pa m-1 s-1/8.9310-4Pa s

R=-1.643109 m

-1


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Appendi 4

8periment brie

Appendi %


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*ata sheet

Appendi *


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&esults table

ElapsedTime

t[s]

BackPressure

P1[bar]

Changein

Pressure[bar]

FlowRate

Q[litrehr]

00:01 0.00 0.00 40.500:10 0.01 0.01 43.9

00:20 0.01 0.01 45.3

00:30 0.01 0.01 45.3

00:40 0.01 0.01 45.3

00:51 0.01 0.01 45.2

01:01 0.01 0.01 45.2

01:11 0.01 0.01 45.2

01:21 0.01 0.01 45.3

01:30 0.01 0.01 45.3

01:40 0.01 0.01 45.2

01:50 0.01 0.01 45.3

02:01 0.01 0.01 45.4

02:11 0.01 0.01 45.3


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02:21 0.02 0.02 45.3

02:31 0.02 0.02 45.3

02:40 0.02 0.02 45.3

02:50 0.02 0.02 45.4

03:00 0.02 0.02 45.3

03:11 0.02 0.02 45.4

03:21 0.02 0.02 45.3

03:31 0.02 0.02 45.3

03:41 0.02 0.02 45.3

03:50 0.02 0.02 45.3

04:00 0.02 0.02 45.2

04:10 0.02 0.02 45.2

04:20 0.03 0.03 45.3

04:31 0.03 0.03 45.3

04:41 0.03 0.03 45.4

04:51 0.03 0.03 45.3

05:00 0.03 0.03 45.3

05:10 0.03 0.03 45.405:20 0.03 0.03 45.3

05:30 0.04 0.03 45.4

05:41 0.04 0.04 45.4

05:51 0.04 0.04 45.4

06:01 0.04 0.03 45.3

06:10 0.04 0.04 45.3

06:20 0.04 0.04 45.3

06:30 0.04 0.04 45.3

06:40 0.04 0.04 45.2

06:51 0.04 0.04 45.3

07:01 0.05 0.05 45.3

07:11 0.05 0.05 45.4

07:21 0.05 0.05 45.3

07:30 0.05 0.05 45.3

07:40 0.05 0.05 45.3

07:50 0.05 0.05 45.5

08:01 0.05 0.05 45.4

08:11 0.05 0.05 45.4

08:21 0.06 0.06 45.4

08:31 0.06 0.06 45.3

08:40 0.06 0.06 45.4

08:50 0.06 0.06 45.3

09:00 0.06 0.06 45.4

09:10 0.06 0.06 45.3

09:21 0.07 0.07 45.3

09:31 0.06 0.06 45.3

09:41 0.07 0.07 45.3

09:50 0.07 0.07 45.3

10:00 0.07 0.07 45.3

10:10 0.07 0.07 45.3

10:20 0.07 0.07 45.3

10:31 0.08 0.07 45.4

10:41 0.07 0.07 45.4

10:51 0.08 0.08 45.4

11:00 0.08 0.08 45.411:10 0.08 0.08 45.4


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11:20 0.08 0.08 45.4

11:30 0.08 0.08 45.3

11:41 0.09 0.08 45.3

11:51 0.08 0.08 45.3

12:01 0.09 0.09 45.3

12:11 0.09 0.09 45.3

12:20 0.09 0.09 45.3

12:30 0.09 0.09 45.3

12:40 0.10 0.10 45.3

12:51 0.09 0.09 45.3

13:01 0.10 0.10 45.4

13:11 0.10 0.10 45.4

13:21 0.10 0.10 45.4

13:30 0.10 0.10 45.4

13:40 0.10 0.10 45.4

13:50 0.11 0.11 45.4

14:00 0.10 0.10 45.3

14:11 0.11 0.11 45.314:21 0.11 0.11 45.3

14:31 0.11 0.11 45.3

14:40 0.11 0.11 45.3

14:50 0.12 0.11 45.3

15:00 0.06 0.06 0.1

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Filtration Experiment