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Penyajian DataKesetimbangan(presentingequilibriumdata)
ThermodynamicconsiderationsandphaseThermodynamicconsiderationsandphaseequilibria:multicomponentmixturesequilibria:multicomponentmixtures
Formulticomponentmixturessimplegraphicalrepresentationsofp p g p pvapourliquidequilibriadatadonotexist
Mostoftensuchdata(includingbinarysystems)isrepresentedintermsofK al es defined asKvaluesdefinedas:
Ki =yi/xicorrelatedempiricallyortheoreticallyintermsoftemperaturepressureandcomposition
The ratio of two K values or relative volatility indicates the relative easeTheratiooftwoKvalues,orrelativevolatility,indicatestherelativeeaseordifficultyofseparatingcomponentsiandj
iii xyK /
jj
ii
j
iij xy
yK /
==
Thermodynamicdataformixtures:Thermodynamicdataformixtures:SimplifiedmodelsSimplifiedmodels
Raoults law (Ideal solution/ideal gas): VRaoult slaw(Idealsolution/idealgas):
siii Pxp = pi isthepartialpressureofcomponenti
T PL
Daltonslaw(Idealgas):
Pyp ii =T,P
Kvalueforidealgas/idealsolutionsystem:
PPK sii /=Relativevolatilityforidealgas/idealsolutionsystem:
sj
siji PPKK // =
Antoineequation:
i
ii
si CT
BATP +=)(ln
Persamaan AntoinePersamaan Antoine
Persamaan Antoine memberikan hubunganPersamaan Antoinememberikan hubungantekanan uap murni (P atau VP)suatusenyawa/komponen dengan suhusenyawa/komponen dengan suhu.
Persamaan Antoinedan koefisien dinyatakandalam beberapa bentuk:dalam beberapa bentuk:
Data koefisien Antoine dapat dilihat diDatakoefisien Antoinedapat dilihat diChemicalEngineeringVol 6
Bentuk lain: Bentuk lain:
De Priester ChartDePriester Chart
Ada 2 jenis grafik:Ada 2jenis grafik: Suhu tinggi Suhu rendah
Grafik menunjukkan hubungan nilai Kuntuksuatu komponen dengan suhu dan tekanansuatu komponen dengan suhu dan tekanan
Lecture5 8
Lecture5 9
DePriester:LowT
10
DePriester Charts:HighT
11
Tugas 1(26/09/2013)Tugas 1(26/09/2013)
Campuran terdiri nhexane nheptane nCampuran terdiri n hexane,n heptane,noctanedan nnonane pada suhu 40Cdan 500kPakPa
Tentukan nilai Kdengan:A G fi (d P i ) A.Grafis (dePriester)
B.Persamaan Antoine
Tugas 2 (26/09/2013)Tugas 2(26/09/2013)
Campuran terdiriCampuran terdiri nhexane(0.15),nheptane (0.20),noctane(0 30) dan n nonane (0 35)(0.30)dan nnonane (0.35)
Tentukan bubblepointdan dewpointpadak 1tekanan 1atm
Penentuan Bubblepointdan Dewpoint
Bubble point is the condition that the firstBubblepointistheconditionthatthefirstbubbleformedduringliquidmixtureboiled
Dew point is the condition that the first drop Dewpointistheconditionthatthefirstdropformedduringvapormixturecooled
ThermodynamiccalculationsusingKThermodynamiccalculationsusingKvaluesvalues
BubbleBubble pointpoint
Dew pointDew point T
P
DewpointDewpoint
TwophasesystemsTwophasesystems Tb(B)
V
GivenP,T,V/(V+L),findGivenP,T,V/(V+L),findx*,y*x*,y*
Given P T x* y* findGiven P T x* y* findTb(A)
GivenP,T,x ,y ,findGivenP,T,x ,y ,findV/(V+L)V/(V+L) L
xAy*x*
Easyfor2componentsystem,ifTxydiagramisavailable(remember the lever rule?)(remembertheleverrule?)
Whataboutthemulticomponentsystem?
ThermodynamiccalculationsusingKThermodynamiccalculationsusingKvaluesvalues
BubbleBubble pointpoint
T Modelsystem:binarymixtureA,BT V
Considertheprocessinthefigure:westartwitha mixture of composition 1 and temperature T1
1=+ BA xxL
amixtureofcomposition1andtemperatureT1andstartincreasingthetemperature
Asweincreasethetemperaturewearegoingtoreachapointwherethefirstbubbleforms
1
Thevapourinthisbubbleobeys:
1=+ BA yy Ontheotherhand:
Thus as we increase the temperature we put new
1)()( =+ BBAA xTKxTK ThusasweincreasethetemperatureweputnewKvaluesintheaboveequationuntilthisconditionismet
ThermodynamiccalculationsusingKThermodynamiccalculationsusingKvaluesvalues
BubblepointBubblepoint
Procedure:Procedure:
a)SelectT
b) K (T)b)Ki(T)
c) i
ii xK
d)ifTistoohigh
e) Adjusting T
1>i
ii xK
e)AdjustingT
g)Finalcompositioncanbecorrectedusing =i
ii
iii xK
xKy
i
ThermodynamiccalculationsusingKThermodynamiccalculationsusingKvaluesvalues
DewDew pointpoint
Modelsystem:binarymixtureA,B1
Considertheprocessinthefigure:westartwitha mixture of composition 1 and temperature T1
1=+ BA yyT V1
amixtureofcomposition1andtemperatureT1andstartdecreasingthetemperature
Aswedecreasethetemperaturewearegoingtoreachapointwherethefirstdropofliquidforms
L
Theliquidinthedropletobeys:
1=+ BA xx Ontheotherhand:
Thus as we decrease the temperature we put new
1)(/)(/ =+ TKyTKy BBAA ThusaswedecreasethetemperatureweputnewKvaluestheaboveequationuntilthisconditionismet
ThermodynamiccalculationsusingKThermodynamiccalculationsusingKvaluesvalues
Procedure:
DewDew pointpoint
Procedure:
a)SelectT
b) K (T)b)Ki(T)
c) i i
i
Ky
d)if Tistoolow
e) Adjusting T
1>i i
i
Ky
e)AdjustingT
g)Finalcompositioncanbecorrectedusing =i
ii
iii Ky
Kyx/
/
i