Nama
: Nur Hamidah
Nrp
: 2308100049
Tugas
: Operasi Teknik Kimia III
Dosen
: Dr. Widyastuti, ST.,MT.
Soal : Comparison of Differential and Flash Distillation
A mixture of 100 kg mol which contains 60 mol % n-pentane (A) and 40 mol % nheptane (B) is vaporized at 101.32 kPa pressure under differential conditions until 40 kg mol are distilled. Use equilibrium data from Example 11.3-2. a) What is the average composition of the total vapor distilled and the composition of the liquid left? b) If this same vaporization is done in an equilibrium or flash distillation and 40 kg mol are distilled, what is the composition of the vapor distilled and of the liquid left? Penyelesaian :
Data kesetimbangan n-pentane x
y
1/y-x
1
1
∞
0,867
0,984
8,547
0,594
0,925
3,021
0,398
0,836
2,283
0,254
0,701
2,237
0,145
0,521
2,660
0,059
0,271
4,717
0
0
∞
L1 = 100 kg mol
L2 = 60 kg mol
x1 = 0,6
V = 40 kg mol
1|Differential and Flash Distillation
a) Differential Distillation ln
ln
x1
L1 L 2
dx
y x
x 2
100 60
0, 6
dx y x
x 2
0, 6
0,5108
x 2
dx y x
9.000 8.000 7.000 6.000 x5.000 y / 1 4.000
3.000 2.000 1.000 0.000 0
0.2
0.4
0.6
0.8
1
x
Trial ke 1, x2 = 0,4 Luas trapesium =
3,2 2,2 2
x0,2 0,540
Hasil trial ke 1 belum mendekati luasan 0,5108,oleh karena itu dilakukan trial ulang. Trial ke 2, x2 = 0,44 Luas trapesium =
3,2 2,4 2
x0,16 0,448
Kemudian dilakukan interpolasi : x 2 0,4 0,44 0,4
0,5108 0,540 0,448 0,540
0,092 x 2 0,0368 0,001168 0,092 x 2 0,037968 x 2 0,4126
2|Differential and Flash Distillation
Neraca massa : L1* x1 L 2 * x 2 ( L1 L 2) yav 100 * 0,6 60 * 0,4126 (40) yav 60 24,756 40 yav
yav 0,8811
Jadi nilai x2 = 0,4126 yav =0,8811
b) Flash Distillation f
V
y
xf
y
xf
40
100
F
0,4
1 f x f f f
0,6
0,4
3 2
Mengeplot garis kesetimbangan antara x dan y dan menggambar slope nya
Grafik Kesetimbangan n-pentane 1 0.9 0.8 0.7 0.6 y0.5
0.4 0.3 0.2 0.1 0 0
0.2
0.4
0.6
0.8
x
Dari grafik grafik diatas diatas didapatkan didapatkan x2=0,38 x2=0,38 dan y2= y2= 0,81
3|Differential and Flash Distillation
1
1.2
