exp 3 gas absorption

8/18/2019 Exp 3 Gas Absorption

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Mass Transfer I CLB 20804

Experiment 3

GAS ABSORPTION

1.0 OBJECTIVES

• To operate vapor – liquid separation process using a Packed Column Gas

A sorption Process !nit"

• To determine percentage removal o# car on dio$ide in a sorption column"

2.0 OVERVIEW

Gas a sorption is a %idel& unit operation in c'emical engineering" T'ere are numerous process

applications %'ere particular components need to e selectivel& removed #rom a gas stream" T'e

t&pe o# contacting unit #or t'e #eed gas and t'e a sor ing liquid can e tailored to t'e application

along %it' t'e c'oice o# t'e a sor ent %'ic' %ill 'ave a 'ig' selectivit& #or t'e desired

components along %it' a 'ig' capacit& #or t'e a sor ed components"

T'e unit consists o# t'ree individual packed a sor er columns %'ic' operate at atmosp'eric

pressure" (ac' column 'as t'e same overall dimensions ut contain a di##erent t&pe o# packing"

T'e columns are arranged so t'at t'e& can e operated independentl& and consequentl& t'e

per#ormance c'aracteristic o# eac' o# t'e packing can e separatel& evaluated and directl&

compared" )ere* a gas stream is usuall& interacted %it' a liquid stream #lo%ing counter current in

order to a##ect t'e mass trans#er" T'e #lo% rates o# liquid and gas 'ave to e care#ull& selected in

order to ac'ieve e##ective mass trans#er" T'is is ac'ieved & recirculating %ater do%n t'e columns

and passing air up t'roug' t'em"

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,igure + s'o%s t'e sc'ematic diagram o# t'e apparatus in t'is e$periment"

,igure +- A sorption !nit

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3.0 EXPERIMENTAL PROCE !RES

3.1 C"emi#$%& $n' $n#i%%$r( e)*ipment& re)*ire' -

PART A+ C"emi#$% Prep$r$ti,n

C'emicals Required"

• +"/ 0 )Cl"

• 1/ 0 NaO)"

Ancillar& equipments required-

• +/ ml Pippette"

• .2 ml and .2/ ml Beaker

• . o# +///ml 3olumetric ,lask

PART A+ C"emi#$% Prep$r$ti,n

PART A 1+ 0.01M -CL &t$n'$r' &,%*ti,n , 1Litre

+" Pour +/ml o# )C4 5+"/ 06 #rom t'e container into 2/ml eaker"

." Pipette +/ ml solution o# )C4 5+"/ 06 into +///ml volumetric #lask"7" Add dioni8ed %ater up to marked level at volumetric #lask"

1" S'ake t'e solution #or a %'ile"

PART A2+ 0.01M N$O- &t$n'$r' &,%*ti,n 1Litre

+" 9eig't /"1g o# 1/0 NaO) pellets"

." Pour t'e /"1g NaO) pellets into +//ml eaker"

7" Add dioni8ed %ater into t'e +//ml eaker"

1" !se magnetic stirrer to dissolve t'e NaO) pellets into 'omogeneous solution"

2" Pour t'e dissolve t'e NaO) pellets into +///ml volumetric #lask"

:" Add dioni8ed %ater up to marked level at volumetric #lask"

;" S'ake t'e solution #or a %'ile"

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:" Turn on t'e po%er s%itc' o# recirculation pump"

;" Slo%l& open valve ,C31 to give t'e required #lo%rate o# /"2 4?min as indicated &

,+7"

@" (nsure t'at t'e liquid over#lo% #rom t'e unit is connected to a suita le drain"

" OPEN valve 3++ and CLOSE 3;"

+/" (nsure t'e liquid inlet valve o# t'e column* i"e" 31* 32 or 3: depending on t'e

column to e used is OPEN "

PART C+ Experiment+ A &,rpti,n , CO 2 int, W$ter r,m Air 5 CO 2 Mixt*re.

+" Open t'e %ater #eed valve graduall& until t'e desired #lo% rate +"2 4?min is ac'ieved

as indicated in ,I7"

." (nsure t'at t'e %ater #lo% rate is allo%ed to sta le #or a out +/ minutes a#ter eac'

c'ange until t'e desired value is reac'ed"

7" epending on t'e column to e operated* OPEN t'e valve 3+* 3.* or 37"

1" Set air #lo%rate & graduall& OPEN t'e #eed valve ,C3+ until t'e desired #lo% rate

a out 1/ 4?min is indicated in t'e #lo% meter ,I+" (nsure t'at t'e %ater #lo% rate is

allo%ed to sta le #or a out +/ minutes a#ter eac' c'ange until t'e desired value is

reac'ed"

2" A#ter stead& state conditions are reac'ed* set CO . #lo%rate & OPEN valve ,C3.

ENTL6 until CO . rate is . 4?min is ac'ieved":" Allo% #urt'er period o# +/ minutes #or t'e A sorption process to attain stead& state

5Consult &our lecturer or tec'nician6"

;" ra% ./ ml sample #rom t'e outlet valve* 3+. #or ever& 2 minutes"

@" Repeat t'e e$periments #or :/ 4?min air #lo%rate

PART + An$%(7e t"e S$mp%e *&in t"e Met",' , ire#t Titr$ti,n in ,r'er t, 'etermine t"e$m,*nt , *nre$#te' N$O- in t"e &$mp%e.

C'emicals Required"• /"/+ 0 )Cl "

• /"/+ 0 NaO)"

• P'enolpt'alein Indicator"

Ancillar& equipments required-

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• 2/ ml Burette and Stand"

• +/ ml Graduated C&linder"

• 2/ ml Pippette"

• +/ ml Pippette"

• +// ml or .2/ ml Conical ,lask"

• .2 ml Beaker

• .2/ ml Beaker

PART + An$%(7e t"e S$mp%e *&in t"e Met",' , ire#t Titr$ti,n in ,r'er t, 'etermine t"e

$m,*nt , *nre$#te' N$O- in t"e &$mp%e.

+" ,ill t'e /"/+0 )C4 solution into 2/ml Burette"

." Pipette +/ ml o# sample into .2/ml conical #lask"

7" Pipette 7/ ml o# solution /"/+0 NaO) into .2/ ml conical #lask t'at containing +/

ml o# sample"

1" Add +=2 drops o# an indicator 5P'enolpt'alein6 to t'e solution"

2" Titrate t'e mi$ture %it' /"/+ 0 )Cl solution" Stop titration process once #irst

permanent pale pink appear 5Consult &our lecturer or tec'nician on 'o% to determine

c'anges o# &our color sample6" T'is is meant to determine t'e amount o# unreacted

NaO) %it' CO . in t'e sample mi$ture"

:" Repeat t'e measurements ever& 2 minutes and carr& out t'e titration %it' 8RES-

samples until CONSTANT concentration o# NaO) 'as een ac'ieved"

;" Record &our results in t'e provided ta le in APPEN IX A.

7"1 ener$% &"*t / ',9n pr,#e'*re&.

+" Close CO . suppl& at valve SG"

." Close t'e Compressed Air #lo% at CA"

7" Stop t'e Circulation Pump"

1" Open 3alve 3++"

2" Allo% ,res' 9ater to enter t'e column #or a #e% minutes to drain o## t'e %ater"

:" Close t'e ,res' 9ater ,lo% at ,9"

;" Close t'e drain valve 3++ %'en t'e #lo% o# %ater 'as stopped"

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:.0 ANAL6SIS AN ISC!SSION

Discuss all your results. The questio s !elo" o ly ser#e as a $ui%eli e. &our %iscussioshould not o ly li'it to these questio s.

+" B& making proper mass alance* calculate t'e percentage removal o# CO . #rom t'e

a sorption column"

." Plot grap' percentage removal percentage removal o# CO . versus air #lo% rate and

discuss t'e e##ect o# air #lo% rate on t'e percentage removal o# CO . "

7" iscuss an& possi le errors in t'e e$periment and state an& recommendation to

improve t'e process"

;.0 RE8ERENCES

+" Tre& al* R"("* (ass Tra s)er *+eratio s, 3 r% e%., 0c=Gra%=)ill* + @+

." 0cCa e Smit'* - it *+eratio s o) Che'ical $i eeri $, 5 th e%, 0c=Gra%=)ill*

+ 7

7" Geankoplis*C"


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APPEN IX A

T$ %e& , Re&*%t&

3olume o# NaO) F m4

3olume o# CO . in sample F m4

Table 1

Air %,9 r$te C,n#entr$ti,n , C,n#entr$ti,n , C,n#entr$ti,n , Per#ent$ e

NA/Exp3/SEPT 2014

Air 8%,9r$te Time< t =min> V,%*me , -C%< mL

1/ 4?min

/

2

+/

+2

./

.2

7/

72

1/

:/ 4?min

2

+/

+2

./

.2

7/

72

@


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CO 2 $t in%et CO 2 in 9$ter CO 2 $t ,*t%et Rem,?$% , CO 2 1/ 4?min@/ 4?min

Table 2

STEP B6 STEP CALC!LATION !I E

T, 'etermine C,n#entr$ti,n , CO 2 $t ,*t%et

Water Inlet C,n#. =CO 2 @$ir> ,*t%et

- 2O @ CO 2 C,n#. =CO 2 @$ir> in%et

Based on elo% reaction-

. NaO) H CO . Na . CO 7 H ) . O

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Na . CO 7 H )C4 CO . H ) . OH NaCl

. moles o# NaO) results %it' + mole o# CO .

4et $ F moles o# NaO) added F /"/+3 +

3 +F volume o# NaO)* 3 . F volume o# )C4

& F moles o# )Cl used F /"/+3 .

T'en*

moles o# NaO) reacted F 5$=&6

moles o# CO . reacted F /"2 5$=&6

)ence*

concentration CO . outlet F /"2 5$=&6? 53CO. sample6

F mol?4iter

C,n#entr$ti,n , CO 2 $t in%et

CO 2 Inlet stream-

."/ 0 1 0 +/min2

min= F/"/+m7

ensit& o# CO . F+" @ 7'$

#olu'e'ass

= ρ

0ass o# CO . F 2$ ' 1'2$

/+A@"//+"/7A@"+ 7

=

0ol o# CO . Fmass CO. ? molar mass CO.

n F 'ole $ 'ole

$ 12"/11

@"+A =

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0'ol

0

'ol

#cco c /12"/

+/

12"/* ===

CO . inlet F 'ol /12"/

CO 2 in 9$ter

CO . in %ater F conc" CO . inlet – conc" CO . outlet

Percentage removal o# CO . #rom t'e column"

removal o# CO . I+//"

" 1

i let co c

outlet Co c=

NA/Exp3/SEPT 2014++

exp 3 gas absorption

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