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Flow Sheets for Basic CHEN Unit Operations
Operations with Mass Transfer
1. DIVIDER/SPLITTER
a. The total balance is A!"#
b. #o$position of strea$s A% ! an& # is the sa$e for each.
c. There in onl' one in&epen&ent $aterial balance since all co$positions
are e()al.
*. MI+ER ,!len&er-
a. There are two or $ore enterin strea$s.
b. There is onl' one eit strea$% a 0$ie&0 strea$.
c. The strea$s can be an' phase% as% li()i& or soli&.
Splitter Feed, A
Splitter Exit 1, B
Splitter Exit 2, C
MIXER
Mixer Feed 2,B
Mixer Feed 1, F Mixer Product, E
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. DR2ER ,Direct 3eatin-
a. Sol4ent strea$ lea4es as a p)re 4apor an& is soli&s free.
b. Eit &rie& soli&s are in the soli& phase.
c. Drie& soli&s $a' not be sol4ent free.
&. 5ee& can be soli&% sl)rr' or sol)tion.
6. 5ILTER
a. 5iltrate% the eit li()i&% is soli&s free.
b. 5iltrate is sat)rate& with sol)ble co$ponent.c. The filter ca7e lea4es with so$e li()i& attache&.
&. #oncentration of strea$ E an& li()i& attache& to the filter ca7e is the
sa$e.
Dryer
Solvent, S
Dryer Feed, D Dried Product, E
Filter
Filter Cae
!et "olid", S
Feed Solution
or Slurry, D
Filtrate
#Exit $i%uid&, E
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8. DISTILLATIO9
a. The $ore 4olatile co$ponents are in the &istillate.
b. The less 4olatile co$ponents are in the botto$s.c. Separation is acco$plishe& b' boilin.
&. Perfect separation is not possible.
:. EVAPORATOR
a. Si$ilar to &r'in% ecept both process strea$s are li()i&s.
Di"tillation
Colu'n#ol)$n 5ee&% 5
Di"tillate, D
Botto'", B
Evaporator
Solvent, S
Evaporator Feed, D Dried Product, E
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;. DE3<MIDI5IER
a. 5ee& strea$ contains a con&ensable co$ponent an& a non=
con&ensable co$ponent.
b. #on&ensate is a li()i& with the con&ensable co$ponent onl'.
c. The 0&r' as0 eit strea$ is sat)rate& with the con&ensable
co$ponent at the T an& P of the process.
>. 3<MIDI5IER
a. The fee& as is not sat)rate&.
b. The li()i& is e4aporate& in the process )nit.
c. The 4apor eit pro&)ct $a' or $a' not be sat)rate&.
De(u'idi)ier
Conden"ate
li%uid, S
Feed *a"
Moi"t *a", DExit *a", E
+u'idi)ier
olatile Feed
li%uid, S
Feed *a" , DExit *a"
!etter -a", E
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?. @AS DR2ER
a. Sol4ent is transferre& fro$ li()i& phase to as phase.
b. <nit can be split into two )nits for anal'sis= a &irect &r'er ,as in -
an& a $ier of the fee& as an& the sol4ent $o4er to the as phase.
1. LEA#3I9@ B E+TRA#TIO9
a. The two li()i& sol4ents $)st be i$$iscible.
b. The' $)st ha4e &ifferent [email protected]. At least one co$ponent is transferre& fro$ one sol4ent to the
other b' &ifference in sol)bilit'.
&. The process is often calle& liquid-liquid extraction.
e. If one of the fee& strea$s is a soli&% the process is calle&
Leachin or li()i&=soli& etraction.
*a" Dryer
Dryer Feed, F
Feed *a", *Exit *a", E
Dry Product, P
Extraction
Colu'n
$i-(t Solvent Feed, F
+eavy Solvent Feed, *Extract $i%uid .ut, E
Ra))inate $i%uid .ut, R
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11. A!SORPTIO9 ,@as Absorption- ,DESORPTIO9-
a. P)rpose of )nit is to ha4e the li()i& absorb a co$ponent fro$ the fee&
as. An absorber is often calle& a scrubber.
b. The li()i& strea$ flows &own thro)h the tower b' ra4it'.
c. The as strea$ is p)$pe& )pwar&s thro)h the tower.
&. 9o carrier as is transferre& to the li()i&.
e. @enerall' no li()i& sol4ent is transferre& to the as strea$ ,chec7 this
ass)$ption-.
f. Desorption is the sa$e process as as absorption ecept that the
co$ponent transferre& lea4es the li()i& phase an& enters the as
phase. A &esorber is so$eti$es calle& a stripper.
A/"or/er
Dirty *a" Feed, F
Feed A/"or/in- $i%uid, *Clean Exit *a", E
Exit $i%uid, P
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1*. PARTIAL #O9DE9SER
a. The fee& strea$ contains onl' con&ensable 4apor co$ponents.
b. The eit strea$s% L an& V% are in e()ilibri)$.c. #on&ensation is ca)se& b' coolin an&/or increasin press)re.
1. 5lash VaporiCer% 5lash Distillation
a. Sa$e flow sheet as a partial con&enser ecept the fee& is a li()i&.
b. VaporiCation is ca)se& b' re&)cin the press)re an& /or heatin.
c. The Vapor an& li()i& strea$s are in e()ilibri)$.
Partial
Conden"er Vapor 5ee&% 5
apor Product,
Conden"ed $i%uid, $
Fla"(
0nit$i%uid Feed, F
apor Product,
$i%uid Producd, $
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1. #R2STALLIER
a. Soli& cr'stals are for$e& in the )nit b' a chane in te$perat)re.
b. The flow sheet for a cr'stalliCer is often shown as a co$bination
cr'stalliCer=filter.
18. REA#TOR ,#he$ical Reactor% co$b)stor% f)rnace% refor$er-
a. The &iara$ shown is for a t'pical reactor that has two reactant fee&
strea$s an& a rec'cle strea$.
b. If a sinle reaction ta7es place% p)t the con4ersion in the bo.
c. A reactor is often na$e& b' the reaction ta7in place.&. A reactor is so$eti$es prece&e& b' a fictitio)s $ier if the co$bine&
reactor fee& is specifie& or $)st be &eter$ine&.
e. M)ltiple eit strea$s are shown to re$in& 'o) to watch for eit
strea$s that separate beca)se of their &ifferent phases.
Cry"tallier
Cry"tallier Feed, C Slurry Product, E
Reactor
Recycle Feed, R
*a" Product", *
Reactant 1 Feed, A
Solid Product", S
Reactant 2 Feed, B $i%uid Product", $