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Transcript of Gas absorption by aladwani
7/23/2019 Gas absorption by aladwani
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Al-Balqa' Applied University
Faculty of Engineering Technology
Department of Chemical Engineering
eport of Control !a"oratory
#as A"sorption
Edited "y$
%haled &aad %halaf ayaif
(eshari )amed A!shammari(ohmmad
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T*T!E+A#E
A"stract,
*ntroduction
Aims.
Theory.
Apparatus and (aterials/-0
(ethodology1-2
esults3-
Calculations45-4
Discussion4.
Conclusion4/
ecommendations40
eferemces41
AB&TACT
Gas absorption is a process in which the soluble parts of mixture are
transferred to a liquid.Gas absorption is done in a packed column .This report
are done as to examine the air pressure drop across the column as a function
of air ow rate for dierent water ow rates through the column. When the
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air pressure drop to certain limit, the phenomena known as ‘ooding will
occur in which the s!stem can no longer operate as it is. "ence the ‘ooding
point is to be determined as to make sure that the process should be made
to operate under the ‘ooding point.
*T6DUCT*6
Gas absorption is a process in which the soluble parts of a gas mixture are
transferred to or dissol#ed in a liquid. The re#erse process, called desorption
or stripping, is used to transfer #olatile parts from a liquid mixture to a gas
$%& . Therefore there will be mass transfer of the component of the gas from
the gas phase to the liquid phase. The solute transferred is said to be
absorbed b! the liquid. 'n gas desorption (or stripping), the mass transfer is
in the opposite direction, of which the transfer is from the liquid phase to the
gas phase. The principles for both s!stems are the same. *ut from here and
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on, we are onl! interested in gas absorption . There are + t!pes of absorption
processes ph!sical absorption and chemical absorption,depending on
whether there is an! chemical reaction between the solute and the
sol#ent(absorbent).
When water and h!drocarbon oils are used as absorbents, no signi-cant
chemical reactions occur between the absorbent and the solute, and the
process is commonl! referred to as ph!sical absorption. When aqueous
sodium h!droxide (a strong base) is used as the absorbent to dissol#e an
acid gas, absorption is accompanied b! a rapid and irre#ersible neutraliation
reaction in the liquid phase and the process is referred to as chemical
absorption or reacti#e absorption.
A*(&
To examine the air pressure drop across the column as a function of air ow
rate for dierent water ow rates through the column.
T)E67
/nother de-nition of gas absorption0desorption is ,a process in which a
gaseous mixture is brought into contact with a liquid and during this contact
a component is transferred between the gas stream and the liquid stream.
The gas ma! be bubbled through the liquid, or it ma! be passed o#er
streams of the liquid, arranged to pro#ide a large surface through which the
mass transfer can occur. The liquid -lm in this latter case can ow down the
sides of columns or o#er packing, or it can cascade from one tra! to another
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with the liquid falling and the gas rising in the counter ow. The gas, or
components of it, either dissol#es in the liquid (absorption) or extracts a
#olatile component from the liquid (desorption). $+&
'n e#er! packed tower with a gi#en sie of packing and t!pe , has an upper
limit to the rate of gas ow known as ooding #elocit! of which the tower
cannot operate abo#e the #elocit! mentioned earlier. /t low gas #elocities
the liquid ows downward through the packing uninuenced b! the upward
gas ow. /s the gas ow rate increases at low gas #elocities the pressure
drop starts to rise at higher rate. The liquid accumulation increases as the
gas ow rate is increased . /t the ooding point, the liquid will no longer
ha#e the abilit! to ow down through the pack column and later is blown out
with or b! the gas. $1&
A++AATU&
The apparatus used in this experiment are
234T567689 /bsorption column (:odel *; <=%7*)
The material used in this experiment is water and air.
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(ET)6D6!6#7 8 +6CEDUE&
A9 #eneral start-up
%. /ll #a#l#es are closed except the #entilation #al#e 8%1.
+. /ll gas connections are ensured of properl! -tted.
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1. The #al#e on the compressed air suppl! line is opened. The suppl!
pressure is setted up in between + to 1 bar b! turning the regulator knob
clockwise.
>. The shut7o #al#e on ?3+ gas c!linder is opened. The ?3+ gas c!linder
pressure is ensured to be su@cient.
=. The power for the control panel is turned on.
B9 E:perimental +rocedures $ )ydrodynamic of a +ac;ed Column
<=et Column +resssure Drop9
%. The general start up procedures are carried out
+. The recei#ing #essel *+ is -lled with =A 4 of water b! opening #al#e 81
and 8=.
1. 8al#e 81 is closed.
>. 8al#e 8%A and #al#e 8B are slightl! opened. The ow of water from #essel
*% through pump ;% is obser#ed.
=. ;ump % is switched on then #al#e 8%% is slowl! opened and adCusted to
gi#e a water ow rate of around % 40min. Water is allowed to enter the top
of column D%, ow down the column and accumulate at the bottom until it
o#erows back to #essel *%.
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E. 8al#e %% is opened and and adCusted to gi#e a water fow rate of A.= 40min
into column D%.
<. 8al#e 8% is opened and adCusted to gi#e an air ow rate of >A40min into
column D%.
F. The liquid and gas ow in the column % are obser#ed , the pressure drop
across the column at d;T7+A% is recorded.
B. 2teps E to < are repeated with dierent #alues of air ow rate, where each
time is increased b! >A40min while the same water ow rate is
maintained.
%A. 2teps = to F are repeated with dierent #alues of water ow rate, of
which each time is increased b! A.=40min b! adCusting #al#e %%.
C9 #eneral &hut-Do>n +rocedures
%. ;ump % is switched o.
+. 8al#es 8%,8+ and 81 are closed
1. The #al#es on the compressed air suppl! line is closed and the suppl!
pressure is exhausted b! turning the regulator knob counterclockwise all
the wa!.
>. The shut7o #al#es on ?3+ gas c!linder is closed
=. /ll liquid in the column in D% is drained b! opening #al#e 8> and 8=.
E. /ll iquid from recei#ing #essels *% and *+ are drained b! opening #al#es
8< and 8F.
<. /ll liquid from pump % is drained b! opening #al#e 8%A.
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F. The power for the control panel is turned o.
E&U!T& AD CA!CU!AT*6&
9low rate
)40min(
;ressure drop (mm"+3)
/ir
water
+A>AEAFA%AA%+A%>
A
%E
A
%F
A
%.AA+E<B%A%F+%=F
+.AF+A1B1A=177
1.AA+<%11B7777
Table % ;ressure rop for Wet column
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9igure % ;ressure rop #s. /ir 9low Hate
&le Calculations
ata
ensit! of air I %.%<=kg0m1
ensit! of waterI BBEkg0m1
?olumn diameter I FAmm
/rea of packed column diameter I A.AA=A+<m+
;acking 9actor I BAA m%
Water #iscosit! I A.AA%Js0m+
Theoretical Flooding +oint$
GG, gas ow rate (kg0m+
s)
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GG I G!Kp 0 /
I
IA.A<<Bkg0m+s
Capacity parameter? y-a:is
I
IIA.A%=>
G4 , liquid owrate per unit column cross7sectional area
I
I
I1.FBEx %A71 kg0m+
9low parameter , x7 axis
x7axisI
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I1.A1+
Water 9low Hate (40min)G4 (kg0m+s)
%.A1.FBEx %A71
+.AE.EAA>
1.AB.BAAE
Table + Water 9lowrate and G4 , 4iquid 9lowrate per Lnit ?olumn ?ross7
sectional /rea
Table 1 /ir 9lowrate
,gas ow rate
(kg0m+s) abr#. GG
,capacit! parameter
and ow parameter.
9igure +
Theoretical ;ressure
rop ?orrelation
?hart 9or Handom
;ackings
11
/ir
ow
rate
(40min)
GG
)kg0m+
s(
?apac
it!
;aram
eter
(!7
axis)
9low parameter (x7axis)
+AA.A<<BA.A%=
>
%.A4;:+.A4;:1.A4;:
>AA.%==<A.AE%
>
1.A1++.B%A+>.1E=1
EAA.+11EA.%1F
1
%.>=EA%.>=EA+.%F>A
FAA.1%%=A.+>=
B
A.B<A=A.AAB<A=%.>==<
%AAA.1FB1A.1F>
%
A.<+<FA.=F+1%.AB%<
%+AA.>E<+A.==1
+
A.AA=F+
1
A.>F=>A.F<1=
%>AA.E++BA.<=1
%
A.<=1%A.>%EAA.<+<B
%EAA.E++BA.BF1
+
A.BF1+A.1E1BA.=>=B
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Water 9low
Hate
)40min(
Theoretical
9looding /ir
9lowrate
(40min)
5xperimental
9looding /ir
9lowrate
(40min)
5rror(M)
%.A%FA%EA%%.%
+.A%>A%+A%>.+F
1.A%AAFA+A
Table > comparison of theoretical and correlation of ooding point
D*&CU&&*6
'n this experiment, the interest is to examine the air pressure drop across the
column as a function of air ow rate for dierent water ow rates through the
column. The experiment based on the ow rate of liquid and gas in the
packed.
9irstl! the water ow rate is kept constant to % 40min and the air ow rate is
then recorded after a % minute inter#al. /ir ow rate is kept rising at constant
b! +A 40min b! each = minutes. /ll reading of pressure drop are then
recorded until the ooding point is reached. The pressure drop for ow rate of
air are A,+,E,<,B,%A,%1,+%,=F mm "+A respecti#el! to
+A,>A,EA,FA,%AA,%+A,%>A,%EA and %FA 40min of air.
The ow rate of water is then adCusted to + 40min, the data recorded are
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F,+,A,1,B,1A,=1 mm "+A respecti#el! to +A,>A,EA,FA,%AA,%+A,%>A,%EA 40min
of air. 't cannot reach %FA 40min of air ow rate as the water will spra!ed out
from the column due to the high ow rate. Theoreticall!, the pressure drop
will increase as the air ow rate of air is increased, howe#er at the beginning
of the experiment , the pump suddenl! failed to work as an o#erow occurs
hence Ceoparding the s!stem of which being experimented.
/s the water ow rate is increased to 1 40min, the datas are , A,+,<,%1,1B mm
"+A respecti#el! to +A,>A,EA and FA 40min of air . *e!ond FA 40min of air , the
ooding occurs.
The graph of column ;ressure rop #s. /ir 9low Hate is plotted and in which
the results from the plotted graph shown the higher the gas ow rate , the
higher the pressure drop.
9or correlated #alue of the pressure drop,calculations has ben made and a
graph of capacit! parameter against ow rate parameter is plotted. The
capacit! parameter is indirectl! proportional to ow rate parameter
C6C!U&*6
'n conclusion, the air pressure drop across the column increases as the air
ow rate increases as well as the water ow rate through the column. 9rom
the experiment, the #alue of experimental pressure drop is higher compared
to the correlated #alues for packed column. 9or packed column of water
owrate of % 4;:, the error in#o#led is the lowest that is %%.% M, followed b!
that of water owrate of + 4;: which is %>.+F M . /t water owrate of 1 4;:,
the error in#ol#ed is +AM . These percentage errors between theoretical andcorrelated calculations of ooding point are slightl! high due to some
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unexpected instrumental error as the pump suddenl! shut o in the middle
of the experiment. "ence, all instruments must be checked before an!
experiment is conducted to ensure the accurac! of the outcomes.
EC6((EDAT*6&
2ome suggestion in impro#ing the safet! are to alwa!s check and rectif! an!
leak and all operating instructions supplied with the unit must be carefull!
read and understood before attempting to operate the unit. Jext, be
extremel! careful when handling haardous, ammable or polluting materials
such as ?3+. :ake sure the s!stem is su@cientl! #entilated when working at
atmospheric pressure.
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EFEECE&
$%&;err!, Hobert "., and Green. ;err!Ns ?hemical 5ngineersN "andbook. Jew
Oork :cGraw7"ill, 'nc. (%BF>), pp%>7E,%F7++7+
$+&Hetrie#ed on %+th :arch,+A%= from
http00www.nifst.org.n0unitoperations0conteqseparationF.htm
$1&Geankoplis, ?.P. (+AA1). Transport ;rocesses and 2eparation ;rocess
;rinciple, >th 5dition. Jew Oork ;rentice "all,ppE=<7EEA
$>&Hetrie#ed on %+th
:arch,+A%= from
)http00www.separationprocesses.com
15