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