lab report exp 4 g13

8/16/2019 Lab Report Exp 4 G13

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2/25

he experiment of batch packed distillation unit !as di"ided into

t!o experiments# In the $rst experiment% the ob&ecti"es !ere to determine

the hei'ht e(ui"alent theoretical plates )*EP+ at total re,ux and the

e-ect of li(uid and "apor loadin' on the *EP at total re,ux#

.ean!hile% the second experiment ob&ecti"e !as to conduct the

batch distillation at constant re,ux# /e need to examine the chan'e in top

and bottom composition% and the hei'ht e(ui"alent theoretical plated

)*EP+ o"er time in a batch distillation# Beside% mass balance calculations

on the distillation unit ha"e to carr0 out#

Before the experiment is bein' conducted it is necessar0 to

di-erentiate !hat t0pe of cate'or0 the batch distillation column is in#

here are "ital information for each of us to kno!% !hich is to di-erentiate

bet!een a unit operation and unit process# he packed bed distillation iscate'ori1ed under unit operation as it has mechanical process !hich

results in the ph0sical chan'e that is "isible to us#

2#0 %(E$)*

Batch distillation% is "er0 important e(uipment used in man0

industries# It is "er0 e2cient and eas0 to use e(uipment# It allo!s the

fractionation of multicomponent mixture into its pure constituents in a

sin'le column# Due to its numerous ad"anta'es such as lo! capital cost%

eas0 approach method and so forth the batch distillation is used as asource of separation# 3t the same time the batch distillation consume too

much of ener'0 and also could de'rade the feed substances due to hi'h

temperature !hich results the materials to decompose#

In order to increase the performance the batch packed distillation

)BPD+ unit is de"eloped# It is used to separate mixtures at the atmospheric

pressure in a batch column# his batch packed is mainl0 desi'ned to

expose the students on the beha"ior of the BPD and for research

purposes# ompare to batch distillation there are some di-erent in the

unit operation# 5or example% !e can obtain the top and bottom product todetermine the refractin' index and also for mass balance calculations# /e

also could determine the ,o! rate b0 manual calculations#


3/25

3#0 E+,E)IE-% DE'IG-

6#7 E8PE9I.E 7: Batch Distillation at otal 9e,ux

7# 5irstl0% !e recorded the top )distillate+ and bottom temperatures#

;# hen !e collected the samples from the distillate and the bottomproduct#

6# /e measured the refracti"e index for both of the samples and

determined their compositions#4# 5or the other "apor and li(uid loadin'% !e ad&usted the heater

po!er settin's in /7 and /;# B0 doin' that it !ill decrease the

heatin' dut0 and the "apor ,o! in the column# It !ill also cause the

li(uid ,o! to decrease#?% @>?% 4>? and ;>?#

6#; E8PE9I.E ;: Batch Distillation at onstant 9e,ux

7# 5irstl0% !e set the po!er settin's to A>?#;# /e !aited approximatel0 for 7< minutes for the distillation unit to

reach stable condition# hen !e recorded the top and bottom

temperature#

6# /e ha"e collected the samples from the distillate and the bottomproduct# 5or all the samples collected% !e compiled all of the

distillate and bottom samples into separate containers for later use

in mass balance calculations#4# hen !e measured the refracti"e index for both of the samples and

determined their compositions# his !ill constitute the composition

at the be'innin' of the experiment# minutes#@# 3fter !aitin'% !e collected the samples from the distillate and

bottom product# /e measured the refracti"e index for both of thesamples and determined their compositions#A# /e measured the distillate ,o! rate b0:

I# losin' "al"e 4 and started the time immediatel0II# ollected the distillate in the measurin' "essel B6 and

stopped the timer once it reached a certain "olume#


4/25

.#0 )E'/L%'

Table A: Table for Preparation of Refractive Index vsComposition Plot

ole raction

ethanol

ole raction o

ater

)eractie

ine4> 7 7#66;CC

>#>6 >#CA 7#6477C>#>A >#C6 7#646>;

>#7; >#== 7#64C4A>#7A >#=6 7#6#;4 >#A@ 7#6#6; >#@= 7#6@7;<>#4; >###4< 7#6@6@4>#@4 >#6@ 7#6@6#A4 >#;@ 7#6@6#=< >#7< 7#6@7 7#6


5/25

Graph of Refractive Index vs Mole Fraction of Ethanol

Figure A shows the graph of refractive index vs mole fraction of

ethanol

E8PE9I.E 7: Batch Distillation 3t otal 9e,ux

(eater12

poer

Bottom Di!tillate-umber

o !tage!

(E%,7mm8)eract#

Ine4ole

raction)eract#Ine4

oleractio

n

7>>? 7#6#7= 7#6@7#6 7 77;>=>? 7#6@>? 7#6#;@ 7#6@7C@ >#64 7 77;>4>? 7#66 >#6< 7 77;>;>? 7#6#7= 7#6@7C@ >#6 7 77;>

Table 1: Results of !TP values for di"erent heater power#


6/25

100 % Heater Power Equiliriu! "ia#ra! for Ethanol $ater &ste ! at 1 at!

> 7 8b 8d

Figure 1#1 shows 1$$ % eater Power !&uilibrium 'iagram for !thanol(ater )*stem at 1 atm


7/25

'0 % Heater Power Equiliriu! "ia#ra! for Ethanol $ater &ste! at 1 at!

> 7 8b 8d

Figure 1#+ shows ,$ % eater Power !&uilibrium 'iagram for !thanol(ater )*stem at 1 atm

(0 % Heater Power Equiliriu! "ia#ra! for Ethanol $ater &ste! at 1 at!

> 7 8b 8d

Figure 1#- shows .$ % eater Power !&uilibrium 'iagram for !thanol(ater )*stem at 1 atm


8/25

)0 % Heater Power Equiliriu! "ia#ra! for Ethanol $ater &ste! at 1 at!

> 7 8b 8d

Figure 1#/ shows /$ % eater Power !&uilibrium 'iagram for !thanol(ater )*stem at 1 atm

*0 % Heater Power Equiliriu! "ia#ra! for Ethanol $ater &ste! at 1 at!

> 7 8b 8d

Figure 1#0 shows +$ % eater Power !&uilibrium 'iagram for !thanol(ater )*stem at 1 atm


9/25

Graph of HE+P vs Heater Power

Figure 1#. shows the relationship between !TP and eater Power


10/25

E8PE9I.E ;#7: Batch Distillation 3t onstant 9e,ux

Table +#1: Results of !TP values at di"erent time#

%ime7min8

Di!tillate Bottom prouct

-umber o !tage

!

(E%,

7mm8

)eract#Ine4

oleraction

9lorate7mL:

min8)eract#Ine4

oleractio

n

> 7#6@7C4 >#6A A7#4;=@ 7#6A >#;@7 77;

>

7> 7#6@7=; >#6< 6> 7#6@;7; >#67 77;

>

;> 7#6@7A; >#66 7;#< 7#6@7>@ >#;=7 77;

>

6> 7#6#67 >#7ACC 7#6@7@7 >;<7 77;

>

4> 7#6#;= >#7AC= 7#6#;@7 77;

>

7#6@77C >#6; >#7AC; 7#6#;=7 77;

>

@> 7#6@;67 >#6@ >#7@A= 7#6@747 >#6; 7 77;>


11/25

0 !in Equiliriu! "ia#ra! for Ethanol,$ater &ste! at 1 at!

> 7 xd 8b

Figure +#1 shows $ min !&uilibrium 'iagram for !thanol(ater )*stem at

1 atm


12/25

10 !in Equiliriu! "ia#ra! for Ethanol,$ater &ste! at 1 at!

> 7 xd 8b

Figure +#+ shows 1$ min !&uilibrium 'iagram for !thanol(ater )*stem at

1 atm

*0 !in Equiliriu! "ia#ra! for Ethanol,$ater &ste! at 1 at!

> 7 xd 8b

Figure +#- shows +$ min !&uilibrium 'iagram for !thanol(ater )*stem at

1 atm


13/25

-0 !in Equiliriu! "ia#ra! for Ethanol,$ater &ste! at 1 at!

> 7 xd 8b

Figure +#/ shows -$ min !&uilibrium 'iagram for !thanol(ater )*stem at

1 atm

)0 !in Equiliriu! "ia#ra! for Ethanol,$ater &ste! at 1 at!

> 7 8d 8b

Figure +#0 shows /$ min !&uilibrium 'iagram for !thanol(ater )*stem at 1 atm


14/25

.0 !in Equiliriu! "ia#ra! for Ethanol,$ater &ste! at 1 at!

> 7 8d 8b

Figure +#. shows 0$ min !&uilibrium 'iagram for !thanol(ater )*stem at

1 atm

.0 !in Equiliriu! "ia#ra! for Ethanol,$ater &ste! at 1 at!

> 7 8d 8b

Figure +#2 shows .$ min !&uilibrium 'iagram for !thanol(ater )*stem at

1 atm


15/25

E8PE9I.E ;#;: 3mount of Ethanol

Table +#+ : Results of Amount of !thanol

%ime

7min8

Di!tillate compo!ition

yBottom compo!ition 4

1

y− x

> >#6A >#;@C#>C>

C

7> >#6< >#;A7;#

>>

;> >#66 >#;C

;>

>>

6> >#66 >#666#66

66

4> >#64 >#6766#66

66

>#6< >#67;>

>>

@> >#6@ >#6;;>

>>

Graph of 1/ d , vs

Figure +#, shows the graph of 13xdxb vs 4ottom !thanol 56b7


16/25


17/25

5#1 DI'C/''I$-

Based on the appendix 3% the refracti"e index for 76 samples of

ethanol !ater mixture !ith di-erent "olumes of !ater and ethanol is

measured# he refracti"e index is measured b0 usin' a refractometer%

!hich is an anal0tic instrument that proposed ori'inall0 b0 Snells la!# Its

a formula used to stud0 the relationship bet!een the an'le of incident andrefraction !hen a speci$c li'ht passin' throu'h a boundar0 of the

medium# he "alues of refracti"e index then are used to produce a

calibration 'raph of refracti"e index "ersus mole fraction of ethanol and

the best linear 'raph is determined# 3s a result% the calibration 'raph

enables us to determine the mole fraction of ethanol at the entire distillate

and bottom product#

ext for 3ppendix B% !e kno! that the e-ecti"e column hei'ht is77;>m and constant throu'hout our experiment# 5rom that% !e !ill beable to calculate the hei'ht e(ui"alent theoretical plates )*EP+ "alue b0di"idin' the e-ecti"e column hei'ht !ith the number of theoretical plates# he "alue for theoretical plates can be referred from the 8F E(uilibriumDia'ram for Ethanol/ater S0stem at 7 atm 'raphs at the appendices# 5orthe result% !e kno! that e"en thou'h the heater po!er is kept increasin'%the *EP &ust kept constant# 9efer to the 'raph of *EP "s *eatin' Po!er#

Lastl0 for 3ppendix % the s0stem !as set at constant re,ux# Gurexperimental "alue $nds that the numbers of theoretical sta'es areincreasin' and then fall do!n a'ain# his also happen to the *EP "alue

as !e as !e kept increase the time of boilin'# his is because there aresome errors in determinin' the 9efracti"e Index "alues for the bottom andtop distillate# Due to hi'h temperature in the boiler% the samples should becool do!n for H7> min% because the temperatures can a-ect the 9I"alues# /e also obser"e that the concentrations of ethanol in the reboilero"er time are decreasin'#

Safet0 Precautions

7# /ear a safet0 'lo"e !hen takin' the samples out of the "al"es to

a"oid scaldin'#he distillate and the bottom product can be hot as it

is heated at => de'ree celcius#


18/25

;# It is ad"ised be careful !hen handlin' ethanol as its hi'hl0

,ammable#

Error and .odi$cations

hrou'hout the experiment% some possible error can be identi$ed and !ecome out !ith se"eral modi$cations to make impro"ement#

Possible errors:

7# .easurement of refracti"e index : he refracti"e index of thesamples is mostl0 measured !hile it is not completel0 cool do!n #

;# Parallax error : he position of e0e is not directl0 perpendicular tothe scale of measurin' c0linder

6# 5luctuation of temperature readin' : he temperature readin' ishardl0 reached stable# It is di2cult to collect the readin' #

.odi$cations:

7# he refracti"e index must be measured !hen the samples arecompletel0 cooled do!n#

;# he position of e0e should be directl0 perpendicular to the scale ofmeasurin' c0linder

6# 9ecord se"eral temperature and calculate the a"era'e temperature

5or the purpose of calibration% the refracti"e index of 76 samples of

ethanol!ater mixture !ith di-erent "olumes of !ater and ethanol is

measured to produce a refracti"e index "ersus mole fraction of ethanol

'raph# his can be made possible b0 usin' refractometer% an anal0tical

instrument that is 'o"erned b0 Snells La!% a formula used to describe the

relationship bet!een the an'les of incidence and refraction% !hen

referrin' to li'ht or other !a"es passin' throu'h a boundar0 bet!een t!o

di-erent isotropic media% such as !ater and 'lass# *a"in' done that% the

"alues of refracti"e index are tabulated alon' !ith its respecti"e ethanol

!ater compositions of "olume# ext% a 'raph of refracti"e index "ersus the

composition of ethanol% 8ethanol is constructed and the best linear 'raph is

determined# 3s a result% an e(uation of 0 >#>;@x J 7#6646 is obtained

!hich then% enables the determination of the mole fraction of ethanol inthe entire distillate and bottom product% x from an0 arbitrar0 "alue of

refracti"e index% 0#

6#0 C$-CL/'I$-

3ll in all% the ob&ecti"es of the experiment are not ful$lled due to the

discrepancies obser"ed bet!een the result of the experiment and the

established theor0# he conclusions that can be dra!n from these

experiments are as follo!#


19/25

In total re,ux condition% the *ei'ht E(ui"alent heoretical Plates )*EP+ at

total re,ux can be determined b0 steppin' o- the theoretical sta'es from

the mole fraction of distillate% 8D until the mole fraction of bottom% 8B to

the 4 > 7 7#66;CC

7 C >#>6 >#CA 7#6477C

; = >#>A >#C6 7#646>;

6 A >#7; >#== 7#64C4A

4 @ >#7A >#=6 7#6#;4 >#A@ 7#6#6; >#@= 7#6@7;<

A 6 >#4; >###4< 7#6@6@4

=#< 7#< >#@4 >#6@ 7#6@6#A4 >#;@ 7#6@6#< >#=< >#7< 7#6@7 > 7 > 7#6


20/25

7min8%em

p)eract#Ine4

oleraction

9lorate7mL:min8

%emp

)eract#Ine4

oleraction

> A4#@ 7#6@7C4 >#6A A7#4;=@ => 7#6A >#;@

7> A@#4 7#6@7=; >#6< 6> =>#7 7#6@;7; >#6

;> A#66 7;#< =>#7 7#6@7>@ >#;=

6> A#67 >#7ACC =>#; 7#6#;<4> A#7AC= =>#; 7#6#;@

A#6 >#7AC; =>#6 7#6#;@

@> A#6 >#7@A= =>#6 7#6@;67 >#;=

able 3#6: 9a! Data for Experiment ;

%ime

7min8

Di!tillate Bottom prouct

%em

p

)eract#

Ine4

ole

raction

9lo

rate7mL:min8

%em

p

)eract#

Ine4

ole

raction

> A4#@ 7#6@7C4 >#6A A7#4;=@ => 7#6A >#;@7> A@#4 7#6@7=; >#6< 6> =>#7 7#6@;7; >#6

;> A#66 7;#< =>#7 7#6@7>@ >#;=

6> A#67 >#7ACC =>#; 7#6#;<

4> A#7AC= =>#; 7#6#;@

A#6 >#7AC; =>#6 7#6#;@

@> A#6 >#7@A= =>#6 7#6@;67 >#;=

Sample alculations

1#1 olar &olume

Ethanol

Speci$c 'ra"it0 >#A=C

.olecular !ei'ht 4@#>A 'Kmol

Molar volume= Molecular weight

Specific gravity of component i × density of water

Molar Volume ( Ethanol )=(46.07 g1mol )×( 1

0.789)×( 1 L

1000 g )=0.05839 L /mol

/ater

Molar Volume (Water )=( 18.02g1mol )×( 1 L

1000 g )=0.01802/mol


21/25

1#2 ole 9raction

Mole fraction of Ethanol= Moles of ethanol

Moles of Ethanol+ Moles of Water

Mole fraction of Water= Moles of water

Moles of Ethanol+ Moles of Water

Gr .ole fraction of !ater )7 .ole 5raction of Ethanol+

olume of ethanol 7 mL >#>>7 L

olume of !ater C mL >#>>C L

Mole of component i=Volume of componenti∈the mixture

Molar volume of componenti

Mole of ethanol= 0.001 L

0.05839 L/mol=0.0171mol

Mole of water= 0.009 L

0.01802 L/mol

=0.4994 mol

Mole fraction of Ethanol= 0.0171

0.0171+0.04994=0.33

Mole fraction of Water=1−0.33=0.7

1#3 ole 9raction o Ethanol u!ing Linear E=uation

5rom the 'raph of 5i'ure 3 !ith refracti"e index as the 0axis and mole fraction

of ethanol as the xaxis is plotted usin' Excel# he calculation for mole fraction of

ethanol for batch distillation at total re,ux can be done b0 tracin' the "alue of

mole fraction !ith the references of refracti"e index that has been 'i"en#

1#. Calculation o (E%,

*EP can be easil0 found !ith the follo!in' e(uation


22/25

HETP= Height of column

um!er of stages

he hei'ht of the column used for batch distillation in this experiment is 77;>

mm# o 'et the number of sta'es% !e appl0 .cabe hiele method b0 assumin'constant molar ,o! rate# 3n x0 e(uilibrium cur"e of !aterethanol mixture and

the line !ith the e(uation of 0x are plotted# hen% dra! a "ertical line strai'ht

up crossin' the x0 e(uilibrium cur"e% startin' from the top and bottom

composition# 5inall0% determine the number sta'es re(uired#

1#5 a!! Balance Calculation!

Initial conditions

9eboiler "olume 7L

9eboiler composition >#;@ )8b taken at t >+

5inal conditions

9eboiler "olume 76#66 L

9eboiler composition >#;= )8b taken at t @> min+

Bottom product "olume taken for I9 determination ;>> mL

Distillate "olume 7#< L

Distillate composition >#6 )8d taken at t @> min+

5inal reboiler "olume Initial reboiler "olume 5inal distillate "olume olume

taken for 9I determination+

3ssume that the "olume taken for I9 determination is small enou'h as compared

to others#

5inal reboiler "olume 7 – 7#< – >#; 76#66 L

1#6


23/25

Graph of 1/ d , vs

o calculate area under the 'raph:

"=1

2( # !n− # !n−1)[( 1 xd− x! )n+( 1 xd− x! )n−1]

ime

op

omposition%

8d

Bottom

omposition%

xb

7Kxdxb3rea Under Mraph

bet!een xn7 and xn

> >#6A >#;@ C#>C>C >#7>=

7> >#6< >#;A 7;#>> >#6A<

;> >#66 >#;C ;>>> >#;C;

6> >#66 >#6 66#6666 >#=66

4> >#64 >#67 66#6666 >#<

>#6< >#67 ;>>> ;#<

@> >#6@ >#6; ;>>>

otal 4#@>=

1#; Calculation o Ethanol Let in the )eboiler

9a0lei'h e(uation is used to $nd the amount of ethanol left in the reboiler#


24/25

∫n1

n0dn

n =∫

x1

x0dx

y− x=ln

n0

n1

dx

y− x

∫ x 1

x 0

¿

¿exp ¿

n1=n0¿

/here:

toinitial time at initial condition%

t)$nal+ time at $nal condition%

xb )ethanol+ bottom composition )from the table at time t >+ >#;@

xd )ethanol+ top composition )from the table at time t >+ >#6A

n1 (ethanol)

total number of moles of ethanol in the reboiler#

n1=0.666 L

1#> a!! Balance on the Di!tillation Column

G"erall mass balance

5 D J B

5 total moleK molar ,o! rate in feed

D total moleK molar ,o! rate in distillate

B total moleK molar ,o! rate in reboiler

omponent mass balance

58> D8d J B8b

8> mole fraction of ethanol in feed

8d mole fraction of ethanol in distillate

8b mole fraction of ethanol in reboiler

7+ 76#66)>#6@+ J 7##6;+


25/25

8> >#6

lab report exp 4 g13

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