EVAPORATOR
ṁsv = 120020,541 kg/hr
T = 256°C
P = 42,2 kg/cm2
H = 2799,8062 kj/kg
T = 168,33℃
P = 7,861 kg/cm2
H = 714.314 kj/kg
T = 25°C
ṁ gas alam = 9230,605 kg/hr
T = 256°C
P = 42,2 kg/cm2
H = 1101,600 kj/kg
ṁ udara = 154532,324 kg/hr
Basis Perhitungan: 1 Jam Operasi
Laju Alir Boiler Feed Water (BFW)
mBFW
=
=
Laju alir steam
(1- blowdown rate)
120020,541 kg
(1-0,05)
= 126337,412 kg
mblowdown
= Laju alir boiler feed water x blowdown rate
= 126337,412 kg x 0,05
= 6239,870 kg
Qblowdown
= mBD x hf
hf
= 1101,600 kj/kg (Berdasarkan steam table pada tekanan 42,2
2
kg/cm dan temperatur 256°C)
Qblowdown
= 6239,870 kg x 1101,600 kj/kg = 6873840,792 kj
Panas Laten
Q = n x ΔHv
Keterangan :
Q
: Panas laten senyawa (kJ)
n
: Kmol saturated liquid (kmol)
ΔHv
: Panas penguapan (kJ/kmol)
Menghitung panas penguapan pada temperatur tertentu dapat dihitung dengan
menggunakan Watson’s correlation:


ΔHv2 = ΔHv1  Tc  T2 
 Tc  Tb 
0 , 38
......... (Felder and Rousseau, Eq. 8.4.8., 2005)
Keterangan:
ΔHv2 : Panas laten pada temperatur T2
ΔHv1 : Panas laten pada temperatur boiling point Tb
Tb
: Normal boiling temperature
Tc
: Temperatur kritis
T2
: Boiling temperature
ΔHv2 = ΔHv1
 Tc  T2 


 Tc  Tb 
0 , 38
ΔHv (100°C) = 40,656 kj/kmol (Felder and Rousseau, Appendix B.1, 2005)
Tc = 374,4 °C
ΔHv (256°C) = 40,656 kj/kmol  374,4  256 
 374,4  100 
ΔHv (256°C) = 29,540 kj/kmol
0 , 38
mSL = mBFW – mBlowdown
= 126337,412 – 6316,870 = 120020,542 kg
nSL = (120020,542 kg) / (18,02 kg/kkmol) = 6660,407 kmol
Qlatent = n x ΔHv
Qlatent = 6660,407 kmol x 29,54 kj/kmol = 196748,423 kj
Qlatent = Qradiasi
Panas pembakaran LNG
QLNG = Qlaten + Qkonveksi
Komposisi Gas Alam
Massa gas alam: 9230,605 kg
Massa
Komponen
%massa
Kmol
CH4
74,95
6918,338
431,264
C2H6
6,77
624,912
20,783
C3H8
5,36
494,760
11,221
C4H10
1,9
175,381
3,018
C5H12
0,54
49,845
0,691
C6H14
0,18
16,615
0,193
CO2
10,3
950,752
21,603
(kg)
Nilai kapasitas panas (Cp) untuk setiap senyawa dalam fase gas pada T = 869°C,
1142 K
𝟏𝟏𝟒𝟐
Senyawa
A
B
C
D
E
∫
𝑪𝒑 𝒅𝑻
𝟐𝟗𝟖
(kJ/kmol K)
CH4
34,942
-3,996 x 10-2
1,918 x 10-4
-1,53 x 10-7
3.932 x 10-11
49,245
C2H6
28,146
4,345 x 10-2
1,895 x 10-4
-1,908 x 10-7
5,335 x 10-11
82,481
C3H8
28,277
1,16 x 10-1
1,96 x 10-4
-2,327 x 10-7
6,867 x 10-11
118,069
C4H10
20,056
2,82 x 10-1
-1,314 x 10-5
-9,457 x 10-8
3,415 x10-11
154,822
C5H12
26,671
3,232 x 10-1
4,282 x 10-5
-1,664 x 10-7
5,604 x 10-11
191,136
C6H14
25,924
4,193 x 10-1
-1,249 x 10-5
-1,592 x 10-7
5,878 x 10-11
226,016
CO2
27,437
4,232 x 10-2
-1,955 x 10-5
3,997 x 10-9
-2,987 x 10-13
40,913
Reaksi 1
CH4 + 2 O2  CO2 + 2 H2O
431,264 kmol CH4 + n1  431,264 kmol CO2 + 862,528 kmol H2O + n2
Excess air 10%
nO2 teoritis = 431,264 kmol C2H6 |
nudara =
1,1 (862,528 kmol O2)
2 kmol O2
1 kmol CH4
= 862,528 kmol O2
= 4518 kmol udara
0,21
n1 = nudara x 0,21 = 4518 x 0,21 = 948,780 kmol O2
Nitrogen Balance
nN2 = 0,79 (nudara) = 0,79 (4518) = 3569,22 kmol N2
Atomic Oxygen Balance
Input = Output
2 kmol O
948,78 kmol O2 |1 kmol O
2
=
n2 (kmol O2)
2 kmol O2
1 kmol O2
+
2 kmol O
1 kmol O
2O
431,264 kmol CO2 |1 kmol CO + 862,528 kmol H2 O |1 kmol H
2
n2 = 86,252 kmol O2
Senyawa
CH4
O2
CO2
H2O
N2
nin
(kmol)
Ĥin
(kJ/kmol)
nout
(kmol)
Ĥout
(kJ/kmol)
431,264
948,780
3569,22
Ĥ1
Ĥ2
-
0
86,252
431,264
862,528
3569,22
Ĥ3
Ĥ4
Ĥ5
Ĥ6
-
CH4 (25℃, 298 K): Ĥ1 = (ΔĤf⁰)CH4 = -74,850 kJ/kmol
O2 (25℃): Ĥ2 = ĤO2 (25℃) = 0 kJ/kmol
1142
CH4 (869℃, 1142 K): Ĥ3 = (ΔĤf⁰)CH4 + ∫298 (𝐶𝑝)𝐶𝐻4 𝑑𝑇
= -74,850 + 49,245 = -25,605 kJ/kmol
O2 (869℃): Ĥ4 = ĤO2 (869℃) = 27,793 kJ/kmol
CO2 (869℃): Ĥ5 = (ΔĤf⁰)CO2 + ĤcO2 (869℃)
= -393,500 + 41,210 = -352,290 kJ/kmol
H2O (869℃): Ĥ6 = (ΔĤf⁰)H2O + ĤH2O (869℃)
= -241,830 + 31,996 = -209,834 kJ/kmol
Senyawa
CH4
O2
CO2
H2O
N2
nin
(kmol)
Ĥin
(kJ/kmol)
nout
(kmol)
Ĥout
(kJ/kmol)
431,264
948,780
3569,22
-74,850
0
-
0
86,252
431,264
862,528
3569,22
-25,605
27,793
-352,290
-209,834
-
∆𝐻CH4 = ∑ 𝑛𝑜𝑢𝑡 Ĥ𝑜𝑢𝑡 − ∑ 𝑛𝑖𝑛 Ĥ𝑖𝑛 = − 298240,383 𝑘𝐽
Reaksi 2
C2H6 + 7/2 O2  2 CO2 + 3 H2O
20,783 kmol C2H6 + n1 kmol O2  41,566 kmol CO2 + 62,349 kmol H2O + n2
kmol O2
Excess air 10%
nO2 teoritis = 20,783 kmol C2H6 |
nudara =
1,1 (72,740 kmol O2)
3,5 kmol O2
1 kmol C2 H6
= 72,740 kmol O2
= 381,019 kmol udara
0,21
n1 = nudara x 0,21 = 381,019 x 0,21 = 80,013 kmol O2
Nitrogen Balance
nN2 = 0,79 (nudara) = 0,79 (381,019) = 301,005 kmol N2
Atomic Oxygen Balance
Input = Output
2 kmol O
80,013 kmol O2 |1 kmol O
2
=
2 kmol O
n2 (kmol O2)
2 kmol O2
1 kmol O2
+
1 kmol O
2O
41,566 kmol CO2 |1 kmol CO + 62,349 kmol H2 O |1 kmol H
2
n2 = 7,273 kmol O2
Senyawa
C2H6
O2
CO2
H2O
N2
nin
(kmol)
Ĥin
(kJ/kmol)
nout
(kmol)
Ĥout
(kJ/kmol)
20,783
80,013
301,005
Ĥ1
Ĥ2
-
0
7,273
41,566
62,349
301,005
Ĥ3
Ĥ4
Ĥ5
Ĥ6
-
C2H6 (25℃, 298 K): Ĥ1 = (ΔĤf⁰)C2H6 = -84,670 kJ/kmol
O2 (25℃): Ĥ2 = ĤO2 (25℃) = 0 kJ/kmol
1142
C2H6 (869℃, 1142 K): Ĥ3 = (ΔĤf⁰)C2H6 + ∫298 (𝐶𝑝)𝐶2 𝐻6 𝑑𝑇
= -84,670 + 82,481 = -2,189 kJ/kmol
O2 (869℃): Ĥ4 = ĤO2 (869℃) = 27,793 kJ/kmol
CO2 (869℃): Ĥ5 = (ΔĤf⁰)CO2 + ĤcO2 (869℃)
= -393,500 + 41,210 = -352,290 kJ/kmol
H2O (869℃): Ĥ6 = (ΔĤf⁰)H2O + ĤH2O (869℃)
= -241,830 + 31,996 = -209,834 kJ/kmol
Senyawa
C2H6
O2
CO2
H2O
N2
nin
(kmol)
Ĥin
(kJ/kmol)
nout
(kmol)
Ĥout
(kJ/kmol)
20,783
80,013
301,005
-84,670
0
-
0
7,273
41,566
62,349
301,005
-2,189
27,793
-352,290
-209,834
-
∆HC2 H6 = ∑ 𝑛𝑜𝑢𝑡 Ĥ𝑜𝑢𝑡 − ∑ 𝑛𝑖𝑛 Ĥ𝑖𝑛 = − 25764,391 𝑘𝐽
Reaksi 3
C3H8 + 5 O2  3 CO2 + 4 H2O
11,221 kmol C3H8 + n1 kmol O2  33,663 kmol CO2 + 44,884 kmol H2O + n2
kmol O2
Excess air 10%
nO2 teoritis = 11,221 kmol C3H8 |
nudara =
1,1 ( 56,105 kmol O2)
5 kmol O2
1 kmol C3 H8
= 56,105 kmol O2
= 293,883 kmol udara
0,21
n1 = nudara x 0,21 = 293,883 x 0,21 = 61,715 kmol O2
Nitrogen Balance
nN2 = 0,79 (nudara) = 0,79 (293,883) = 232,167 kmol N2
Atomic Oxygen Balance
Input = Output
2 kmol O
61,715 kmol O2 |1 kmol O
2
=
n2 (kmol O2)
2 kmol O2
1 kmol O2
2 kmol O
+
1 kmol O
2O
33,663 kmol CO2 |1 kmol CO + 44,884 kmol H2 O |1 kmol H
2
n2 = 5,61 kmol O2
Senyawa
C3H8
O2
CO2
H2O
N2
nin
(kmol)
Ĥin
(kJ/kmol)
nout
(kmol)
Ĥout
(kJ/kmol)
11,221
61,715
232,167
Ĥ1
Ĥ2
-
0
5,61
33,663
44,884
232,167
Ĥ3
Ĥ4
Ĥ5
Ĥ6
-
C3H8 (25℃, 298 K): Ĥ1 = (ΔĤf⁰)C3H8 = -103,800 kJ/kmol
O2 (25℃): Ĥ2 = ĤO2 (25℃) = 0 kJ/kmol
1142
C3H8 (869℃, 1142 K): Ĥ3 = (ΔĤf⁰)C3H8 + ∫298 (𝐶𝑝)𝐶3 𝐻8 𝑑𝑇
= -103,800 + 118,069 = 14,269 kJ/kmol
O2 (869℃): Ĥ4 = ĤO2 (869℃) = 27,793 kJ/kmol
CO2 (869℃): Ĥ5 = (ΔĤf⁰)CO2 + ĤcO2 (869℃)
= -393,500 + 41,210 = -352,290 kJ/kmol
H2O (869℃): Ĥ6 = (ΔĤf⁰)H2O + ĤH2O (869℃)
= -241,830 + 31,996 = -209,834 kJ/kmol
Senyawa
C3H8
O2
CO2
H2O
N2
nin
(kmol)
Ĥin
(kJ/kmol)
nout
(kmol)
Ĥout
(kJ/kmol)
11,221
61,715
232,167
-103,800
0
-
0
5,61
33,663
44,884
232,167
14,269
27,793
-352,290
-209,834
-
∆HC3H8 = ∑ 𝑛𝑜𝑢𝑡 Ĥ𝑜𝑢𝑡 − ∑ 𝑛𝑖𝑛 Ĥ𝑖𝑛 = − 19956,669 𝑘𝐽
Reaksi 4
C4H10 + 13/2 O2  4 CO2 + 5 H2O
3,018 kmol C4H10 + n1 kmol O2  12,072 kmol CO2 + 15,090 kmol H2O + n2
kmol O2
Excess air 10%
nO2 teoritis = 3,018 kmol C4H10 |
6,5 kmol O2
1 kmol C4 H10
= 19,617 kmol O2
kmol O )
nudara = 1,1 ( 19,617
= 102,755 kmol udara
0,21
2
n1 = nudara x 0,21 = 102,755 x 0,21 = 21,578 kmol O2
Nitrogen Balance
nN2 = 0,79 (nudara) = 0,79 (102,755) = 81,176 kmol N2
Atomic Oxygen Balance
Input = Output
21,578 kmol O2 |
2 kmol O
1 kmol O2
=
2 kmol O
n2 (kmol O2)
2 kmol O2
1 kmol O2
+
1 kmol O
2O
12,072 kmol CO2 |1 kmol CO + 15,090 kmol H2 O |1 kmol H
2
n2 = 1,961 kmol O2
Senyawa
C4H10
O2
CO2
H2O
N2
nin
(kmol)
Ĥin
(kJ/kmol)
nout
(kmol)
Ĥout
(kJ/kmol)
3,018
21,578
81,176
Ĥ1
Ĥ2
-
0
1,961
12,072
15,090
81,176
Ĥ3
Ĥ4
Ĥ5
Ĥ6
-
C4H10 (25℃, 298 K): Ĥ1 = (ΔĤf⁰)C4H10 = -124,700 kJ/kmol
O2 (25℃): Ĥ2 = ĤO2 (25℃) = 0 kJ/kmol
1142
C4H10 (869℃, 1142 K): Ĥ3 = (ΔĤf⁰)C4H10 + ∫298 (𝐶𝑝)𝐶4 𝐻10 𝑑𝑇
= -124,700 + 154,822= 30,122 kJ/kmol
O2 (869℃): Ĥ4 = ĤO2 (869℃) = 27,793 kJ/kmol
CO2 (869℃): Ĥ5 = (ΔĤf⁰)CO2 + ĤcO2 (869℃)
= -393,500 + 41,210 = -352,290 kJ/kmol
H2O (869℃): Ĥ6 = (ΔĤf⁰)H2O + ĤH2O (869℃)
= -241,830 + 31,996 = -209,834 kJ/kmol
Senyawa
C4H10
O2
CO2
H2O
N2
nin
(kmol)
Ĥin
(kJ/kmol)
nout
(kmol)
Ĥout
(kJ/kmol)
3,018
21,578
81,176
-124,700
0
-
0
1,961
12,072
15,090
81,176
30,122
27,793
-352,290
-209,834
-
∆HC4 H10 = ∑ 𝑛𝑜𝑢𝑡 Ĥ𝑜𝑢𝑡 − ∑ 𝑛𝑖𝑛 Ĥ𝑖𝑛 = − 6988,393 𝑘𝐽
Reaksi 5
C5H12 + 8 O2  5 CO2 + 6 H2O
0,691 kmol C5H12 + n1 kmol O2  3,455 kmol CO2 + 4,146 kmol H2O + n2 kmol
O2
Excess air 10%
nO2 teoritis = 0,691 kmol C5H12 |
8 kmol O2
= 5,528 kmol O2
1 kmol C4 H10
kmol O )
nudara = 1,1 ( 5,528
= 28,956 kmol udara
0,21
2
n1 = nudara x 0,21 = 28,956 x 0,21 = 6,081 kmol O2
Nitrogen Balance
nN2 = 0,79 (nudara) = 0,79 (28,956) = 22,875 kmol N2
Atomic Oxygen Balance
Input = Output
2 kmol O
6,081 kmol O2 |1 kmol O
2
4,146 kmol H2 O
=
n2 (kmol O2)
2 kmol O2
1 kmol O2
2 kmol O
+ 3,455 kmol CO2 |1 kmol CO +
2
1 kmol O
|1 kmol H O
2
n2 = 0,553 kmol O2
Senyawa
C5H12
O2
CO2
H2O
N2
nin
(kmol)
Ĥin
(kJ/kmol)
nout
(kmol)
Ĥout
(kJ/kmol)
0,691
6,081
22,875
Ĥ1
Ĥ2
-
0
0,553
3,455
4,146
22,875
Ĥ3
Ĥ4
Ĥ5
Ĥ6
-
C5H12 (25℃, 298 K): Ĥ1 = (ΔĤf⁰)C5H12 = -146,400 kJ/kmol
O2 (25℃): Ĥ2 = ĤO2 (25℃) = 0 kJ/kmol
1142
C5H12 (869℃, 1142 K): Ĥ3 = (ΔĤf⁰)C5H12 + ∫298 (𝐶𝑝)𝐶5 𝐻12 𝑑𝑇
= -146,400 + 191,136 = 44,736 kJ/kmol
O2 (869℃): Ĥ4 = ĤO2 (869℃) = 27,793 kJ/kmol
CO2 (869℃): Ĥ5 = (ΔĤf⁰)CO2 + ĤcO2 (869℃)
= -393,500 + 41,210 = -352,290 kJ/kmol
H2O (869℃): Ĥ6 = (ΔĤf⁰)H2O + ĤH2O (869℃)
= -241,830 + 31,996 = -209,834 kJ/kmol
Senyawa
C5H12
O2
CO2
H2O
N2
nin
(kmol)
Ĥin
(kJ/kmol)
nout
(kmol)
Ĥout
(kJ/kmol)
0,691
6,081
22,875
-146,400
0
-
0
0,553
3,455
4,146
22,875
44,736
27,793
-352,290
-209,834
-
∆HC5 H12 = ∑ 𝑛𝑜𝑢𝑡 Ĥ𝑜𝑢𝑡 − ∑ 𝑛𝑖𝑛 Ĥ𝑖𝑛 = − 1970,602 𝑘𝐽
Reaksi 6
C6H14 + 19/2 O2  6 CO2 + 7 H2O
0,193 kmol C6H14 + n1 kmol O2  1,158 kmol CO2 + 1,351 kmol H2O + n2 kmol
O2
Excess air 10%
nO2 teoritis = 0,193 kmol C6H14 |
9,5 kmol O2
1 kmol C6 H14
= 1,834 kmol O2
kmol O )
nudara = 1,1 ( 1,834
= 9,606 kmol udara
0,21
2
n1 = nudara x 0,21 = 9,606 x 0,21 = 2,017 kmol O2
Nitrogen Balance
nN2 = 0,79 (nudara) = 0,79 (9,606) = 7,588 kmol N2
Atomic Oxygen Balance
Input = Output
2 kmol O
2,017 kmol O2 |1 kmol O
2
=
n2 (kmol O2)
1 kmol O
2O
1,351 kmol H2 O |1 kmol H
n2 = 0,184 kmol O2
2 kmol O2
1 kmol O2
2 kmol O
+ 1,158 kmol CO2 |
+
1 kmol CO
2
nin
Ĥin
nout
Ĥout
(kmol)
(kJ/kmol)
(kmol)
(kJ/kmol)
C6H14
0,193
Ĥ1
0
Ĥ3
O2
2,017
Ĥ2
0,184
Ĥ4
CO2
-
-
1,158
Ĥ5
H2O
-
-
1,351
Ĥ6
7,588
-
7,588
-
Senyawa
N2
C6H14 (25℃, 298 K): Ĥ1 = (ΔĤf⁰)C6H14 = -167,2 kJ/kmol
O2 (25℃): Ĥ2 = ĤO2 (25℃) = 0 kJ/kmol
1142
C6H14 (869℃, 1142 K): Ĥ3 = (ΔĤf⁰)C6H14 + ∫298 (𝐶𝑝)𝐶6 𝐻14 𝑑𝑇
= -167,2 + 226,016 = 58,816 kJ/kmol
O2 (869℃): Ĥ4 = ĤO2 (869℃) = 27,793 kJ/kmol
CO2 (869℃): Ĥ5 = (ΔĤf⁰)CO2 + ĤcO2 (869℃)
= -393,500 + 41,210 = -352,290 kJ/kmol
H2O (869℃): Ĥ6 = (ΔĤf⁰)H2O + ĤH2O (869℃)
= -241,830 + 31,996 = -209,834 kJ/kmol
nin
Ĥin
nout
Ĥout
(kmol)
(kJ/kmol)
(kmol)
(kJ/kmol)
C6H14
0,193
-167,2
0
58,816
O2
2,017
0
0,184
27,793
CO2
-
-
1,158
-352,290
H2O
-
-
1,351
-209,834
7,588
-
7,588
-
Senyawa
N2
∆HC6H14 = ∑ 𝑛𝑜𝑢𝑡 Ĥ𝑜𝑢𝑡 − ∑ 𝑛𝑖𝑛 Ĥ𝑖𝑛 = − 654,054 𝑘𝐽
QLNG = ∑ (∆𝐻CH + ∆HC2 H6 + ∆HC3 H8 + ∆HC4 H10 + ∆HC5 H12 + ∆HC6 H14 + ∆HCO2 )
4
QLNG = [(−298240,383) + (−25764,391) + (−19956,669) + (−6988,393)
+ (−1970,602) + (−654,054) + 0] 𝑘𝐽
QLNG = −353574,492 kJ
Panas Konveksi
QLNG
= Qlaten + Qkonveksi
Qkonveksi = QLNG − Qlaten
Qkonveksi =
353574,492 kj − 196748,423 kj
Qkonveksi = 156826,069 kj
Laju Alir Flue Gas
CO2
Reaksi
H2 O
O2
N2
Mol
Massa
Mol
Massa
Mol
Massa
Mol
Massa
(kmol)
(kg)
(kmol)
(kg)
(kmol)
(kg)
(kmol)
(kg)
1
431,264 18979,928 862,528 15538,442
86,252
2760,064
3569,22
100009,500
2
41,566
1829,319
62,349
1123,217
7,273
232,736
301,005
8434,160
3
33,663
1481,508
44,884
808,585
5,61
179,520
232,167
6505,319
4
12,072
531,288
15,09
271,846
1,961
62,752
81,176
2274,552
5
3,455
152,054
4,146
74,690
0,553
17,696
22,875
640,957
6
1,158
50,963
1,351
24,338
0,184
5,888
7,588
212,616
Total
523,178 23025,063 990,348 17841,119 101,833 3258,656 4214,031
mCO2 = 18979,928 + 1829,319 + 1481,508 + 531,288 + 152,054 + 50,963 +
950,748 = 23975,811 kg
mfg = mCO2 + mH2O + mO2 + mN2
= (23975,811 + 17841,119 + 3258,656 + 118077,1) kg = 163839,736 kg
118077,1
Komponen
Laju Alir (kg/hr)
Input
Output
Boiler feed water
126337,411
-
Gas alam
9230,605
-
Udara
154532,324
-
Steam
-
120020,541
Flue gas
-
163839,736
Blowdown
-
6239,87
Total
290100,340
290100,147