05_Pulsed Column Liquid - Liquid Extraction 2014
Transcript of 05_Pulsed Column Liquid - Liquid Extraction 2014
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Experiment 4
Pulsed Column Liquid Liquid Extraction Unit.
1. Objective:
The students should be able to:
o Operate a Liquid Liquid Extraction Experiment using a Pulsed Column Liquid Liquid
Extraction Unit.
o To determine the tie lines connecting the bimodal curves in the toluene!ateracetone
s"stem.
o To determine the height equivalent theoretical plates #$ETP% &or column b" using
equilateral triangular diagram.
o To investigate the e&&ect o& the pulsation stro'e on the $ETP.
2. Introduction.
Extractionis a unit operation used to separate components based on their Chemical (i&&erences
instead o& di&&erences in Ph"sical Properties. )hen separation o& components o& a Liquid
*ixture becomes ine&&ective or ver" di&&icult b" means o& (istillation+ and then Liquid
Extractionis one o& the main alternatives to consider.
, !idel" used terminolog" describes the s"stem in terms o& :
o F : Feed.
o S : Solvent
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o S : Solvent
has the same components as the Feed+ though the proportions are di&&erent. On the other hand+
the Extract Streamconsists o& the required component
#SoluteorExracted Component% and Solvent#Extracting SolventorExtractant%. Thedi&&erence bet!een the Extracted !om"onent#Solute% and the Extractin% Solventor
Extractantshould be made clear at all times.
ince the Feedis a t!o component s"stem+ b" convention+ the material to be Extracted is
commonl" re&erred to as the Solute!hile the other component is generall" re&erred to as the
&iluent.
The Raffinatehas the same components as the Feed+ though hope&ull" it is much less
concentrated in Solutei.e.+ it is said to be leaner. ,n ideal unit !ith per&ect Extractiongives aRaffinate!hich has one component onl"+ that being 'ure &iluent.
The liquid used to strip the Solute&rom the Feedis re&erred to as the Solvent. $o!ever+ Solventis a general term and can sometimes be con&using as &or example b" describing the &iluentas the
Feed Solvent. The term Feed Solventshould then be avoided. The Solventa&ter becoming
enriched in solute leaves the s"stem as the Extract.
The 'ulsed !olumn Liquid # Liquid Extraction (nit #*odel: P!"% has been designed to
demonstrate the )asic 'rinci"les of a Liquid # Liquid Extraction 'rocess.
The /ormal *ode o& Operation is that the Light Phase and $eav" Phase Liquids are pumped
Counter Currentl" into the Pac'ed Extraction Column. The $eav" Phase !ill enter the top o& the
column and &lo! do!n!ards+ !hile the Light Phase !ill enter the bottom o& the column and &lo!
up!ards due to (ensit" (i&&erences. Counter Current 0lo! among the pac'ings in the column
and pulsation o& the t!o phases !ill cause the trans&er o& olute Component &rom one phase #Raffinate% to the other # Extract %. The 1a&&inate !ill emerge at the bottom !hile the Extract
!ill emerge at the top o& the Extraction Column. This Liquid # Liquid Extraction 'rocessis
carried out among the Column Pac'ings to give a higher degree o& separation.
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-. !emicals and ncillar$ Equi"ments Required:
a.% Chemicals 1equired.
o ,cetone #olute%.
o (iioni>ed)ater# (iluent%
o Toluene #olvent%.
b.% ,ncillar" Equipments 1equired:
T!o 6ml ?ug and t!o 67ml bea'ers.
eparating &unnels#0or settling and separating the mixtures%
Conical &las's
*easuring C"linder and standard laborator" apparatus
1e&ractometer .
+. O"eratin% Instructions.
+.1 /eneral Start0u" 'rocedures.
-. Prepare the &ollo!ing chemicals :
a% 0eed #$eav"'ase%: *ixture ocetone $ %ater &olution. Prepare 6 litres o&
7!t @ mixture o& #cetone in )ater b" mixing appropriate quantities o& the
#cetonein (istilled )ater.
b% Prepare 6 litres o& Solvent#Light'ase%:Pure 'oluene.
6 Ensure that all valves are closed
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-. Once the liquid starts to over&lo! at the top o& the column+ stop Pump P6.
--. The unit is no! read" &or experiment.
+.2 /eneral Sut # &own 'rocedures.
-. !itch o&& pumps P-+ P6 and P=.
6. Close valves 5= and 5;.
=. Open valves 57+ 5A and 5 to drain all liquid &rom the experiment.
;. Open valves 5-= and 5-; to drain all liquid &rom the 1eceiving 5essels 3= and 3;.
7. Turn o&& the po!er &or the control panel.
'R
+.- &etermination of Equilibrium Solute &istribution 3ie lines4
'RO!E&(RES
-. Prepare A heterogeneous mixtures o& !ater+ acetone and toluene in A di&&erent conical&las's according to the compositions recommended in the table in appendix 0.
6. ,gitate the mixtures prepared in step - &or about ; minutes.
5ote To prevent emulsi&ication+ do not agitate the mixture too vigorousl".
=. top the agitator. Pour each o& the mixtures into a separating &unnel. Let the mixture
settle into t!o distinct clear la"ers !ith a sharp inter&ace.
;. )ithdra! a sample o& each phase and measure the re&ractive index o& each phase. ,gain+
ta'e an average o& three readings &or each phase. The !ater rich phase #ra&&inate% !ouldbe the heav" phase and toluene rich phase !ould be the light phase #extract%.
7. 1epeat the experiment #step 6 to =% &or all mixtures.
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'RO!E&(RES
-. Per&orm the general start up procedures #ection ;.-%
6. Turn on the both pumps P- and P6 and set the desired 0eed and olvent &lo! rates b"
adDusting the pumps &requencies and displacements.
=. 8eep the pulsator pump P= turned o&&.
;. ,llo! both liquids to &lo! into the collection vessels 3= and 3; respectivel". The
bottom product contains the )ater 1ich Phase #1a&&inate % !hile the top product contains
the Toluene 1ich Phase # Extract %.
7. *onitor the 2nter&ace Level. *aintain it at about 6= cm above the olvent inlet b"
adDusting the height o& the Over&lo! Tube.
A. Turn on the Pulsator Pump P= and set the Pulsation tro'e Length.
B. Let the experiment run &or a !hile to attain stead" state.
9. Open valve 5- to !ithdra! a - ml sample o& 1a&&inate and open valve 5-6 to collect a- ml sample o& Extract .
5ote Ta'e samples at suitable time intervals and measure their 1e&ractive
2ndices. )hen the readings are consistent over time+ stead" state has been
reached.
. 1ecord the 1e&ractive 2ndex o& both samples and use the given Calibration Curves
#,ppendix 3% to determine the ,cetone #olute% composition in each phase.
-. 1ecord all data in the given ample Table in appendix ,.
--. 1epeat the experiment #steps = to -% b" turning on the pulsator pump P= and changing
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6% (etermine the required theoretical extraction stage &rom the pulsed column liquid
liquid extraction experiment results. 1e&er to ""endix ! &or a step b" step
calculation guide.
=% Calculate the height equivalent theoretical plates #$ETP% o& the extraction column &or
di&&erent pulsation stro'e.
9E' : Effective column ei%t * 5o of teoretical "lates
;% 0rom the available data+ do a mass balance calculation around the extraction column and
obtain the extract and ra&&inate &lo! rates.
7% (iscuss the various &actors that !ould help to increase the rate o& trans&er o& solute to
solvent phase.
A% Explain ho! pulsation &requenc" increases the trans&er rate in pulsed columns.
;.< REFERE5!ES
-. *cCabe and mith+ #67%+ $nit 'perations of Chemical Engineering+ BthEdition+ *c4ra!
$ill.
6. 1obert E.Tre"bal.+ #-9-%+(ass Transfer 'perations+ =rdEdition+ *c4ra!$ill.
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''E5&I=
'R +.+ &etermination of Equilibrium Solute &istribution 3ie lines4
5o
mount in mixture 3mL4 6ater ric "ase oluene Ric 'ase
cetone 6ater olueneRefractive
Index
cetone
!om"osition
3wt>4
Refractive
Index
cetone
!om"osition
3wt>4- 6
6 ; 9 9
= A B B
; 9 A A
7 - 7 7
A -6 ; ;
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''E5&I= )
'R )+.+ Ex"eriment Extraction of cetone from 6ater (sin% oluene.
Results
0eed 12
0eed Composition
0eed
&lo!rat
e
#L
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''E5&I= !1
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""endix &
SE' )7 SE' !L!(LIO5 /(I&E
-. Obtain the equilibrium data &rom ,ppendix E or &rom literature. Plot the
binodal
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""endix &
;. Locate the point F1+!here all operating lines should meet.
7. (ra! a tie line &rom point E to its equilibrium point on the bimodal plot. Connect an
operating line &rom that equilibrium end o& the tie line to point F1. Extend that operating
line so that it intersects !ith the bimodal plot at the other end. (ra! another tie line &rom
that ne! intersection and continue until a tie line has passed the operating line connecting
1 and .
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""endix E
Equilibrium data )inodal* Solubilit$ &ata for cetone0oluene06ater S$stem
oluene Ric "ase 6ater Ric "ase
cetone 3wt
>4 6ater3wt>4
oluene3wt
>4
cetone 3wt
>4 6ater3wt>4 oluene3wt>4.B 6.;6 9B.B9 A=.= 6-.A9 -;.=
-.;9 6.6 BB.A A=.-; 6;.99 --.9
;-.A- =.B 7;.;6 79.9; =;.6B A.7
76.= 7.6B ;6.;= 7-.66 ;7.A9 =.-
A.AB B.6 =6.-; =.A7 79.B -.=9
A=.79 66.7; -=.9 -.; B9.9A -.6
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*4/Jan 14-A
''E5&I= F