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7/27/2019 Abubakar Adeni Assg4 Permas02

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Abubakar Adeni

1106068516

Teknik Kimia

9.15 A solution of Acetone and Water containing 50 wt% each is to be continuously

fractionated at standard atmospheric pressure at rate 4000 kg/h. The distillate

product is to contain 95 wt % acetone , the residue 0.5%. The feed will be 30 mol%

vaporized before it enters the tower. A total condenser will be used, and reflux will be

returned at the bubble point.

T X1 Y1 73.26 0.47 0.81

Deg C 72.85 0.48 0.82

100.00 0.00 0.00 72.43 0.49 0.83

99.26 0.01 0.04 72.02 0.50 0.83

98.53 0.02 0.07 71.62 0.51 0.84

97.80 0.03 0.10 71.22 0.52 0.84

97.08 0.04 0.14 70.83 0.53 0.85

96.37 0.05 0.17 70.44 0.54 0.86

95.67 0.06 0.20 70.05 0.55 0.86

94.98 0.07 0.22 69.67 0.56 0.87

94.30 0.08 0.25 69.30 0.57 0.87

93.62 0.09 0.28 68.92 0.58 0.88

92.95 0.10 0.30 68.55 0.59 0.88

92.29 0.11 0.33 68.19 0.60 0.89

91.64 0.12 0.35 67.83 0.61 0.8991.00 0.13 0.37 67.47 0.62 0.90

90.36 0.14 0.40 67.12 0.63 0.90

89.73 0.15 0.42 66.77 0.64 0.90

89.11 0.16 0.44 66.43 0.65 0.91

88.50 0.17 0.46 66.09 0.66 0.91

87.89 0.18 0.48 65.75 0.67 0.92

87.29 0.19 0.49 65.41 0.68 0.92

86.70 0.20 0.51 65.08 0.69 0.92

86.12 0.21 0.53 64.76 0.70 0.93

85.55 0.22 0.55 64.43 0.71 0.93

84.98 0.23 0.56 64.11 0.72 0.93

84.42 0.24 0.58 63.79 0.73 0.94

83.86 0.25 0.59 63.48 0.74 0.94

83.32 0.26 0.60 63.17 0.75 0.94

82.77 0.27 0.62 62.86 0.76 0.95

82.24 0.28 0.63 62.56 0.77 0.95

81.71 0.29 0.64 62.26 0.78 0.95

81.19 0.30 0.66 61.96 0.79 0.95

80.68 0.31 0.67 61.66 0.80 0.96

80.17 0.32 0.68 61.37 0.81 0.96

79.67 0.33 0.69 61.08 0.82 0.96

79.18 0.34 0.70 60.79 0.83 0.97

78.69 0.35 0.71 60.51 0.84 0.97

78.20 0.36 0.72 60.23 0.85 0.97

77.73 0.37 0.73 59.95 0.86 0.9777.26 0.38 0.74 59.67 0.87 0.97


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76.79 0.39 0.75 59.40 0.88 0.98

76.33 0.40 0.76 59.12 0.89 0.98

75.88 0.41 0.77 58.86 0.90 0.98

75.43 0.42 0.78 58.59 0.91 0.98

74.99 0.43 0.78 58.33 0.92 0.99

74.55 0.44 0.79 58.06 0.93 0.99

74.11 0.45 0.80 57.81 0.94 0.9973.69 0.46 0.81 57.55 0.95 0.99

57.29 0.96 0.99

57.04 0.97 0.99

56.79 0.98 1.00

56.54 0.99 1.00

56.30 1.00 1.00

a) Determine the product rates, kg/h.

b) Determine the minimum reflux ratio.

c) Determine the minimum number of theoritical trays, graphically and by means

of eq.(9.85)

d) Determine the number of theoritical trays required at reflux ratio equal to

twice the minimum and the position of feed tray.

e) Estimate the overall tray efficiency of a sieve-tray tower of conventional

design and the number of real trays.

f) Using the distillate temperature as the base temperature, determine the

enthalpy of the feed, the products, and the vapor entering the condenser.

Determine the heat loads of the condenser and reboiler. Latent and spesific

heats are available in The Chemical Engineers Handbook, 5th

ed., pp. 3-116

and 3-129.

Penyelesaian

Diketahui:

F = 4000 kg/h GF = 30%

Acetone : zF = 50 wt% Water : zF = 50 wt%

xD = 95 wt% xD = 5 wt%

xW = 0,5 wt% xW= 99,5 wt%

Mr = 58 gr/mol Mr = 18 gr/mol


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5. Membuat garis operasi enriching (hubungkan titik pertemuan garis operasi feed dan

garis kesetimbangan dengan titik pertemuan garis distilat dan diagonal)

Titik potong antara feedline dengan kurva kesetimbangan dan titik akhir

X2 = 0.157

Y2 = 0.424

X1 = 0.95

Y1 = 0.95

! !!

!!

!!

= ! !!!!

!!

! 0.95

0.424 0.95= ! 0.95

0.157 0.95

! = !.!!"!+ !.!"#6. Menentukan rasio reflux minimum

!!

!!+ 1

= 0.38

0.855

!!+ 1

= 0.38

!!= 1,67


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C. Determine the minimum number of theoritical trays, graphically and by means of

eq.(9.85)

Menentukan jumlah kolom teoritis

!!+ 1 =

log0.855

1 0.855

1 0.0015

0.0015

log5.532

!!+ 1 = 4.83

!!= 3.83 4

y = 1.5362x3 - 3.5798x2 + 3.034x + 0.0264

0.00

0.20

0.40

0.60

0.80

1.00

0.00 0.20 0.40 0.60 0.80 1.00

Y

X

x-y Chart


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Berdasarkan grafik diperoleh minimum tray sebanyak 5 Tray

D. Determine the number of theoritical trays required at reflux ratio equal to twice the

minimum and the position of feed tray.

Reflux ratio minimum = 1.67. Sedangkan apabila reflux rationya menjadi dua kali

reflux ratio minimum, intercept garis operasi enrichingnya menjadi (R= 2 Rm)

! =!

! + 1! + !"

! + 1

! =3,34

3,34+ 1! + 0.855

3,34+ 1

! = 0.769! + 0.196

Untuk mendapatkan Stripping line mencari titik potong antara enriching line dengan

feed line sehingga didapatkan seperti persamaan berikut ini :0.769! + 0.196 = 2.33! + 0.79


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Sehingga didapat :

X : 0.1917 Y :0,3434

Berdasarkan grafik yang didapatkan, jumlah tray yang dibutuhkan pada saat R = 2R

adalah 7 tray dan feed masuk pada tray ke 3.


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8

e) Estimate the overall tray efficiency of a sieve tray tower of conventional design and

the number of real trays.

Dari grafik kita dapat menghitung efisiensi tray dengan terlebih dahulu menghitung

nilai av x L. Nilai yang diketahui adalah :

av =5,532

L = 6,03 x 10-4

sehingga didapat av x L= 3,33 x 10-3. Jika dimasukkan ke grafik maka didapat nilai

Eo (Efisiensi trays ) sebesar 0,51.

Dari nilai efisiensi diatas maka dapa dihitung real trays dengan persamaan berikut ini

!!=

!"#$%&!"!"#$%!"#$%!"#$%!"&!"#$%&!"!"#$!"#$%!"!"#$%&

0.38 =7

!"#$%&!"!"#$!"#$%!"#$%!"&= 18,42 18


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Jadi jumlah trays pada kenyataannya adalah 18

f) Using the distillate temperature as the base temperature, determine the enthalpy of

the feed, the products, and the vapor entering the condenser. Determine the heat loads

of the condenser and reboiler. Latent and spesific heats are available in The

Chemical Engineers Handbook, 5th

ed., pp. 3-116 and 3-129.

Heat loads of the condenser (QC)

QC = D [(R + 1) HG1 R HL0 HD]

Heat loads of the reboiler (QB)

QB = D HD + W HW + QC + QL F HF

Diketahui dari pembahasan sebelumnya:

F = 145,595 kmol/h

D = 40,139 kmol/h

W = 105,455 kmol/h

R = 2 Rm = 3.34

q = 0.7

Basis: 1 jamfeed

Untuk aceton (A)

Untuk temperature 56,3 C, didapatkan:

Enthalpy of vaporization (Hvap) = 29,121 kj/mol

AV = (xFxf) + (yFyf)AV = (0.237 x 29,121 kJ/mol) + (0.763 x 40,706 kJ/mol)

= 37,960 kJ/mol

q = (H Cp dT)/AV

0.7 (J/mol K)= (H x 124.700 J/mol K) / 37,960 x 1000 J/mol

H = 213.087 J/mol

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