Vaporizer 481650
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Vaporizer Fungsi
: Menguapkan air dan sedikit aseton sebanyak 19950,843 kg/j dari hasil recycle menara distilasi (MD-01) dan air proses yang selanjutnya dipisahkan antara uap dan cairan dalam separator untuk diumpankan kembali dalam reaktor.
Jenis alat : HE Shell and Tube. Media pemanas : Steam jenuh Prinsip kerja : Cairan dimpankan kedalam vaporizer kemudian dipanaskan dengan suatu media pemanas (umpan tidak kontak langsung dengan media pemanas). Biasanya tidak semua umpan dapat teruapkan dengan sempurna. Produk yang dihasilkan (uap dan cairan) dipisahkan dalam suatu tangki pemisah. Uap yang dihasilkan kemudian digunakan untuk proses selanjutnya, cairan yang tidak menguap direcycle kembali. Bagan unit Vaporizer dan Separator steam
Vaporizer t2
t1 = ? tf
recycle
Umpan segar
1
Komposisi bahan masuk vaporizer Komponen aseton H2O jumlah
kg/jam BM kgmol/jam yi 47,112 58,078 0,811 0,000734 19903,731 18,016 1104,781 0,999 19950,843 1105,592 1,000
Fluida dingin : Suhu masuk = 53°C Kecepatan massa, W : Umpan awal (air + recycle dari MD)
= 19950,843 kg/j
Umpan total yang teruapkan
= 80 % , maka
Umpan total masuk vaporizer
= (19950,843/0,80) = 24938,554 kg/j = 54980,1 lb/j
Massa total
= umpan total masuk vaporizer – umpan segar = (24938,554 – 19950,843) kg/jam = 4987,711 kg/j = 10996 lb/j
Jumlah aseton dalam umpan sangat sedikit maka dapat diabaikan, sehingga suhu penguapan ditetapkan berdasarkan titik didih air dan tekanan umpan. Suhu umpan masuk
: = 99,256ºC
Tekanan umpan
: 1,4 atm
Ditetapkan suhu penguapan : 109,7ºC Neraca Panas Suhu dasar = 32°F (berdasarkan table 7.kern,D,Q..1950,p.817) Preheater : Entalphi pada umpan masuk T
Q1
=
Tref
mdT
Data cairan masing-masing komponen. = a1 + bT + cT^2 + dT^3 + e^4
2
Komponen
a
b
c
d
e
H2O
2,76E+05
-2,09E+03
8,13E+00
-1,41E-02
CH3COCH3
1,36E+05
-1,77E+02
2,84E-01
6,89E-04
T
9,37E-06
= 99,256ºC = 371,13 K
Komponen
(kg/jam)
dt (kkal/kg)
m dt (kkal/jam)
H2O
19903,731
75,145
1495675,405
CH3COCH3 Total
47,112 19950,843
40,748
1919,718 1497595,123
Jadi Q1 = 1497595,123 kkal/jam Entalphi pada massa recycle berupa cairan pada suhu 109,7ºC T
Q2
=
T
= 109,7ºC = 382,7 K
Tref
mdT
Komponen
(kg/jam)
dt (kkal/kg)
m dt (kkal/jam)
H2O
4987,711
85,864
428265,2061
CH3COCH3 Total
0 4987,711
46,979
0,000 428265,206
Q2
= 428265,206 kkal/jam
Q camp
= Q1 + Q2 = 1497595,123 kkal/jam + 428265,206 kkal/jam = 1925860,329 kkal/jam T
(m1+m2).ΔT =
Tref
T
m1..dT + Tref
m2..dT
= 1925860,329 kkal/jam Q campuran adalah umpan segar dan recycle dalam bentuk cair sehingga menggunakan kapasitas panas cairan. Dengan cara triyal didapat. Pada T = 374,212 K = 101,212ºC Komponen
(kg/jam)
dt (kkal/kg)
m dt (kkal/jam)
3
H2O
24891,442
77,291
1923882,295
47,112
41,986
1978,035
CH3COCH3 Total
24938,554
1925860,329
Panas massa campuran (umpan segar + recycle separator) (qp) qp
= 1925860,329 kkal/kg = 7642430 Btul/j
Panas penguapan Enthalphi pada suhu penguapan T = 109,7ºC = 382,7 K T
qv = mΔHfg +
m dT
Tref
ΔHfg pada suhu 109,7 ºC = 957,176 kJ/kg = 228,771 kkal/kg mΔHfg = (24938,554 kg/jam)( 228,771 kkal/kg) = 5705217,937 kkal/jam Data uap masing-masing komponen. = a + bT + cT^2 + dT^3 Komponen
a
b
c
H2O
7,701
4,60E-04
CH3COCH3
1,505
6,22E-02
Komponen
(kg/jam)
d -8,59E10
2,5210E-06 -2,99E-05
4,87E-09
dt (kkal/kg) m dt (kkal/jam)
H2O
24891,442
38,159
949829,7341
CH3COCH3 Total
47,112 24938,554
27,954
1316,968 951146,702
qv
= 5705217,937 + 951146,702 = 6656364,639 kkal/jam = 26414600 BTU/jam
Beban panas total dari vaporizer: Q
= qp + qv = (1925860,329 + 6656364,639)kkal/jam = 8582224,969 kkal/jam = 34057000 BTU/jam
Media pemanas:
4
Digunakan superheated steam suhu 250°F (121,111°C) Panas pengembunan, Hv = 945,4 Btu/lb
(steam table)
Dari perhitungan sebelumnya : Beban panas vaporizer, Q = 8582224,969 kkal/j = 34057000 Btu/j Kebutuhan steam : W = Q/Hv W =
34057000 Btu / j 945,4 Btu/lb
= 36023,905 lb/j = 16340,2 kg/j Menentukan Δt weighted : LMTD =
T 2 T1 T2 , ln( ) T1
(Δtp) = LMTD =
121,111 101,351 121,111 99,256 121,111 101,351 ln 121,111 99,256
= 20,862°C = 69,5516°F (Δtv) = LMTD =
121,111 99,256 121,111 109,7 121,111 99,256 ln 121,111 109,7
= 16,526°C = 60,9278°F qp 7642430 Btu / j = = 109881,441 Btu/j.°F tp 69,5516 0 F 26414600 Btu / j qv = = 433539,370Btu/j.°F+ tv 60,9278 0 F
qv
tv
= 543420,810 Btu/j.°F
Q 34057000 Btu / j 0 F qv = Δt weighted = tv 543420,810 Btu/j0 F = 62,672°F = 20,6022°C
Pemilihan UD Dari tabel 8 Kern 1965 : UD antara 50 ─ 100
Btu/j.ft².°F ( Steam - medium
organik)
5
Diambil UD = 63 Pemilihan alat Dipilih tube : 16 BWG, OD = 1,5 in, ID = 1,4 in Panjang = 16 ft Surface perlin ft = 0,3925 ft²/ft Luas alir, at' = 1,54 in²/tube A
=
Q UD . T 2
A = heat transfer area, ft Q = baban panas, Btu/lb ∆T = true temperature different, 34057000 Btu/j
= 63 Btu/j.ft².F x 62,672 F = 8625,727 ft² Jumlah tube
=
A 8625,727 ft² L. at ' ' 16 ft x 0.3925 ft²/ft
= 1373,523 Dari tabel 9 Kern, dipilih ukuran alat: HE shell & tube dengan spesifikasi sbb: SHELL :
TUBE :
ID = 39 in Baffle = 6 in
Jumlah tube = 1377 DO, BWG, Pitch = 0,75 in; 17 BWG ; 0,94 in Triangular
= 1
=1
Koreksi A: A =L.surface perlint.Ntube = 16 ft x 0.3925 ft²/ft x 1377 = 8647,560 ft² Koreksi UD: UD
=
Q A . T 34057000 Btu/j
= 8647,560 ft² x 62,672 F
6
= 62,841 Btu/j.ft².°F Fluida panas (steam) melalui tube. Fluida dingin melalui shell. Sisi Tube Koefisien transfer panas pengembunan steam, hio = 1500 Btu/j.ft².° (Kern, 1965) Flow area, at' = 1,54 in²/tube at =
Nt . at' 144 . n
at’ = luas penampang tube, in2 Nt = jumlah tube n = tube es =
1377 x 1,54 144 x 1
= 14,726 ft Kecepatan massa steam, Gt: Gt = W/at, (W = aliran massa, lb/j) =
36023,905lb/j 14,726 ft 2
= 2446,238 lb/j.ft² µ steam = 0.0167 = 0.0404 lb/j.ft Ret =
D.Gt (0,1167) x 2446,238 = 0.0404
= 7064,217 (digunakan untuk menghitung pressure drop) hio untuk steam = 1500 Sisi Shell Preheating: Flow area, as =
ID. C' . B 144 . PT
keterangan : as = luas untuk aliran fluida, ft² ID = diameter dalam shell, in B = jarak baffle, in PT = pitch, in
7
C' = clearence = PT - D0 Flow area, as =
(39/12)(0.19)(6) 144 . (0,94)
= 0,328 ft² Diameter ekuivalen, De = 0.95 in = 0.0792 ft ( fig.28 Kern ) Kecepatan massa, GS = W/as Gs = 54980,1/ 0,328 = 167388,806 lb/j.ft² Ta = (T1 + T2)/2 = (99,256 + 101,212)/2 = 100,234°C = 212.421ºF Sifat - sifat fisis pada suhu 100,234°C : = 0,09 Btu/lb.°F µ = 0.07 lb/j.ft k = 0,0135 Btu/j.ft.°F Bilangan Prant'l, Pr = c .µ /k =
0.09 x 0,07 = 4,67E-01 0.0135
Bilangan Reynold, Res = Gs.De/µ =
167388,806 x 0.0792 = 189388,478 0.07
Dari figur 28 Kern, 1965 didapat : faktor perpindahan panas, jH = 290 ho
De
jH = x k ho
ho
x (Prs)-1/3
= jH x
k x (Prs)1/3 De
= 290x
0.0135 x (4,67E-01)1/3 0.0792
φ≈1 ho = shell out heat transfer coefficient, Btu/j.ft2.oF = 38,342 Btu/j.ft².°F Clean overall coefficient for preheating, Up: Up
=
1500 x 38,342 hio . ho = 1500 38,342 hio ho
= 37,386 Btu/j.ft².°F Clean surface required for preheating, Ap:
8
7642430 Btu / j 0 F
qp
Ap = Up . tp = = 204417,284 ft² 37,386 Btu/j.ft 2 . 0 F Vaporization : Sifat - sifat fisis pada suhu 109,7°C : c = 0,45 Btu/lb.°F µ = 0,014 = 0,0315 lb/j.ft k = 0,0142 Btu/j.ft.°F Bilangan Prant'l, Pr = c .µ /k =
0.45x 0.0315 = 0,998 0.0142
Bilangan Reynold, Res = Gs.De/µ =
167388,806 x 0.0792 = 420863,285 0.0315
Dari figur 28 Kern, 1965 didapat : faktor perpindahan panas, jH = 480 ho
De
jH = x k ho
ho
= jH x = 480 x
x (Prs)-1/3
k x (Prs)1/3 De 0.0142 x (0,998)1/3 0.0792
φ≈1 ho = 86,010 Btu/j.ft².°F Clean overall coefficient for vaporization, Uv: Uv
=
1500 x 86,010 hio . ho = 1500 86,010 hio ho
= 81,346 Btu/j.ft².°F Clean surface required for vaporization, Av: qv
26414600 Btu / j 0 F
Av = Up . tv = = 324720,280 ft² 81,346 Btu/j.ft 2 . 0 F Total clean surface, Ac: Ac = Ap + Av = 204417,284 + 324720,280 = 529137,564 ft² Weighted clean overall coefficient
9
Uc
U.A
=
Ac
=
(37,386 x 204417,284 (81,346 x 324720,280) 529137,564
= 78,363 Btu/j.ft².°F Dirt factor : Rd
78,363 - 63 Uc - UD = 78,363 x 63 Uc . UD
=
= 0,00311 /(Btu/j.ft².°F) Rd minimum = 0.003 Cek flux maksimum : Luas transfer panas yang digunakan untuk penguapan: 324720,280 Av xA x 8647,560 = 5306,821 ft² 529137,564 Ac 7642430 qv = = 8647,560 = 883,767 Btu/j.ft² A
= Flux
Flux maksimum = 20000 Btu/j.ft² ( Kern,1965) PENURUNAN TEKANAN Sisi Tube Pt
f.Gt².L.n
= 0.5 5,22.1010.D.S.
Dimana: f = friction factor Gt = kecepatan aliran massa dalam tube, lb/j L = panjang pipa. ft D = diameter tube, ft S = specific gravity
Ret =
7064,217
10
Dari fig.26 Kern 1965, f = 0.00027 D Gt
= 1,4 in = 0,1167 ft = 2446,238 lb/j.ft² ρ = 17.4444 lb/ft3
Sp.gravity, S = ρ/62.5 = 0.279 Pt
= 0.5
(0.00027).(2446,238)².(16).(1) (5.22 x 1010 ).(0.1167) .(0.279).(1)
= 0,0000076 Psi dP allowble (gas ) = max 10 psi Sisi Shell Preheating : Ps =
f.Gs².Ds.(N 1) 5,22.1010.D.S.
Bilangan Reynold, Res = Gs.De/µ = 189388,478 Untuk Res = 189388,478 dari fig.29 Kern, didapat f = 0.00013 Panjang zone preheating, Lp = L.Ap/Ac = 6,181 ft Jumlah cross, N+1 = 12.Lp/B N + 1 = 12 x 6,181/ 7 = 12,362 Pada ta = 99,220°C ρ
= 17,6316 lb/ft3
Sp.gravity, S = ρ/62.5 = 0.282 ID shell = 39 in = 3,25 ft Gs
= 167388,806 lb/j.ft²
Ps
=
(0.00013).(167388,806 ) 2 .(3,25).(12,326) (5.22 x 1010 ).(0.0792).(0.282).(1)
= 0,126 Psi Vaporization : Bilangan Reynold, Res = Gs.De/µ Re = 36841,702 Untuk Res = 45705 dari fig.29 Kern, didapat f = 0,00011 Panjang zone vaporization, Lv = L-Lp = 16 – 13,926 = 2,074 ft Jumlah cross, N+1 = 12.Lp/B
11
N + 1 = 12 x 2,074 / 7 = 3,556 Pada ta = 109,7 °C ρ uap = 17.4444 lb/ft3 sp gas = 0.279 S rata-rata = (0.282 + 0.279)/2 = 0,281 Ps
=
(0.00011). (167388,806) 2 .(3,25).(19,638) (5.22 x 1010 ).(0.0792).(0.281).(1)
= 0,17 Psi Pressure Drop di Shell = 0,126 + 0,17 = 0,295 Psi Summary Tube 1500
Shell h outside
38,342
86,010 Uc 78,363 UD 62,841 Rd hitung 0,00311 Rd minimum 0.003 0,0000076 P hitung 0,295 2
P maksimum
10
Spesifikasi alat vaporizer Fungsi
: Menguapkan air dan sedikit aseton sebanyak 19950,843 kg/j dari hasil recycle menara distilasi (MD-01) yang selanjutnya dipisahkan antara uap dan cairan dalam separator untuk diumpankan kembali dalam reaktor.
Tube
: OD = 0,75 in ; 16 BWG ; 0,94 in triangular pitch ; Nt = 1377 tube ; 1 es
Luas Transfer Panas (A) Shell
: 8647,560 ft² : ID =39 in ; 1 es
12
Jenis
:HE Shell and Tube
Beban Panas Jumlah
: 8582224,969 kkal/j : 1 buah
13
: Menguapkan air dan sedikit aseton sebanyak 19950,843 kg/j dari hasil recycle menara distilasi (MD-01) dan air proses yang selanjutnya dipisahkan antara uap dan cairan dalam separator untuk diumpankan kembali dalam reaktor.
Jenis alat : HE Shell and Tube. Media pemanas : Steam jenuh Prinsip kerja : Cairan dimpankan kedalam vaporizer kemudian dipanaskan dengan suatu media pemanas (umpan tidak kontak langsung dengan media pemanas). Biasanya tidak semua umpan dapat teruapkan dengan sempurna. Produk yang dihasilkan (uap dan cairan) dipisahkan dalam suatu tangki pemisah. Uap yang dihasilkan kemudian digunakan untuk proses selanjutnya, cairan yang tidak menguap direcycle kembali. Bagan unit Vaporizer dan Separator steam
Vaporizer t2
t1 = ? tf
recycle
Umpan segar
1
Komposisi bahan masuk vaporizer Komponen aseton H2O jumlah
kg/jam BM kgmol/jam yi 47,112 58,078 0,811 0,000734 19903,731 18,016 1104,781 0,999 19950,843 1105,592 1,000
Fluida dingin : Suhu masuk = 53°C Kecepatan massa, W : Umpan awal (air + recycle dari MD)
= 19950,843 kg/j
Umpan total yang teruapkan
= 80 % , maka
Umpan total masuk vaporizer
= (19950,843/0,80) = 24938,554 kg/j = 54980,1 lb/j
Massa total
= umpan total masuk vaporizer – umpan segar = (24938,554 – 19950,843) kg/jam = 4987,711 kg/j = 10996 lb/j
Jumlah aseton dalam umpan sangat sedikit maka dapat diabaikan, sehingga suhu penguapan ditetapkan berdasarkan titik didih air dan tekanan umpan. Suhu umpan masuk
: = 99,256ºC
Tekanan umpan
: 1,4 atm
Ditetapkan suhu penguapan : 109,7ºC Neraca Panas Suhu dasar = 32°F (berdasarkan table 7.kern,D,Q..1950,p.817) Preheater : Entalphi pada umpan masuk T
Q1
=
Tref
mdT
Data cairan masing-masing komponen. = a1 + bT + cT^2 + dT^3 + e^4
2
Komponen
a
b
c
d
e
H2O
2,76E+05
-2,09E+03
8,13E+00
-1,41E-02
CH3COCH3
1,36E+05
-1,77E+02
2,84E-01
6,89E-04
T
9,37E-06
= 99,256ºC = 371,13 K
Komponen
(kg/jam)
dt (kkal/kg)
m dt (kkal/jam)
H2O
19903,731
75,145
1495675,405
CH3COCH3 Total
47,112 19950,843
40,748
1919,718 1497595,123
Jadi Q1 = 1497595,123 kkal/jam Entalphi pada massa recycle berupa cairan pada suhu 109,7ºC T
Q2
=
T
= 109,7ºC = 382,7 K
Tref
mdT
Komponen
(kg/jam)
dt (kkal/kg)
m dt (kkal/jam)
H2O
4987,711
85,864
428265,2061
CH3COCH3 Total
0 4987,711
46,979
0,000 428265,206
Q2
= 428265,206 kkal/jam
Q camp
= Q1 + Q2 = 1497595,123 kkal/jam + 428265,206 kkal/jam = 1925860,329 kkal/jam T
(m1+m2).ΔT =
Tref
T
m1..dT + Tref
m2..dT
= 1925860,329 kkal/jam Q campuran adalah umpan segar dan recycle dalam bentuk cair sehingga menggunakan kapasitas panas cairan. Dengan cara triyal didapat. Pada T = 374,212 K = 101,212ºC Komponen
(kg/jam)
dt (kkal/kg)
m dt (kkal/jam)
3
H2O
24891,442
77,291
1923882,295
47,112
41,986
1978,035
CH3COCH3 Total
24938,554
1925860,329
Panas massa campuran (umpan segar + recycle separator) (qp) qp
= 1925860,329 kkal/kg = 7642430 Btul/j
Panas penguapan Enthalphi pada suhu penguapan T = 109,7ºC = 382,7 K T
qv = mΔHfg +
m dT
Tref
ΔHfg pada suhu 109,7 ºC = 957,176 kJ/kg = 228,771 kkal/kg mΔHfg = (24938,554 kg/jam)( 228,771 kkal/kg) = 5705217,937 kkal/jam Data uap masing-masing komponen. = a + bT + cT^2 + dT^3 Komponen
a
b
c
H2O
7,701
4,60E-04
CH3COCH3
1,505
6,22E-02
Komponen
(kg/jam)
d -8,59E10
2,5210E-06 -2,99E-05
4,87E-09
dt (kkal/kg) m dt (kkal/jam)
H2O
24891,442
38,159
949829,7341
CH3COCH3 Total
47,112 24938,554
27,954
1316,968 951146,702
qv
= 5705217,937 + 951146,702 = 6656364,639 kkal/jam = 26414600 BTU/jam
Beban panas total dari vaporizer: Q
= qp + qv = (1925860,329 + 6656364,639)kkal/jam = 8582224,969 kkal/jam = 34057000 BTU/jam
Media pemanas:
4
Digunakan superheated steam suhu 250°F (121,111°C) Panas pengembunan, Hv = 945,4 Btu/lb
(steam table)
Dari perhitungan sebelumnya : Beban panas vaporizer, Q = 8582224,969 kkal/j = 34057000 Btu/j Kebutuhan steam : W = Q/Hv W =
34057000 Btu / j 945,4 Btu/lb
= 36023,905 lb/j = 16340,2 kg/j Menentukan Δt weighted : LMTD =
T 2 T1 T2 , ln( ) T1
(Δtp) = LMTD =
121,111 101,351 121,111 99,256 121,111 101,351 ln 121,111 99,256
= 20,862°C = 69,5516°F (Δtv) = LMTD =
121,111 99,256 121,111 109,7 121,111 99,256 ln 121,111 109,7
= 16,526°C = 60,9278°F qp 7642430 Btu / j = = 109881,441 Btu/j.°F tp 69,5516 0 F 26414600 Btu / j qv = = 433539,370Btu/j.°F+ tv 60,9278 0 F
qv
tv
= 543420,810 Btu/j.°F
Q 34057000 Btu / j 0 F qv = Δt weighted = tv 543420,810 Btu/j0 F = 62,672°F = 20,6022°C
Pemilihan UD Dari tabel 8 Kern 1965 : UD antara 50 ─ 100
Btu/j.ft².°F ( Steam - medium
organik)
5
Diambil UD = 63 Pemilihan alat Dipilih tube : 16 BWG, OD = 1,5 in, ID = 1,4 in Panjang = 16 ft Surface perlin ft = 0,3925 ft²/ft Luas alir, at' = 1,54 in²/tube A
=
Q UD . T 2
A = heat transfer area, ft Q = baban panas, Btu/lb ∆T = true temperature different, 34057000 Btu/j
= 63 Btu/j.ft².F x 62,672 F = 8625,727 ft² Jumlah tube
=
A 8625,727 ft² L. at ' ' 16 ft x 0.3925 ft²/ft
= 1373,523 Dari tabel 9 Kern, dipilih ukuran alat: HE shell & tube dengan spesifikasi sbb: SHELL :
TUBE :
ID = 39 in Baffle = 6 in
Jumlah tube = 1377 DO, BWG, Pitch = 0,75 in; 17 BWG ; 0,94 in Triangular
= 1
=1
Koreksi A: A =L.surface perlint.Ntube = 16 ft x 0.3925 ft²/ft x 1377 = 8647,560 ft² Koreksi UD: UD
=
Q A . T 34057000 Btu/j
= 8647,560 ft² x 62,672 F
6
= 62,841 Btu/j.ft².°F Fluida panas (steam) melalui tube. Fluida dingin melalui shell. Sisi Tube Koefisien transfer panas pengembunan steam, hio = 1500 Btu/j.ft².° (Kern, 1965) Flow area, at' = 1,54 in²/tube at =
Nt . at' 144 . n
at’ = luas penampang tube, in2 Nt = jumlah tube n = tube es =
1377 x 1,54 144 x 1
= 14,726 ft Kecepatan massa steam, Gt: Gt = W/at, (W = aliran massa, lb/j) =
36023,905lb/j 14,726 ft 2
= 2446,238 lb/j.ft² µ steam = 0.0167 = 0.0404 lb/j.ft Ret =
D.Gt (0,1167) x 2446,238 = 0.0404
= 7064,217 (digunakan untuk menghitung pressure drop) hio untuk steam = 1500 Sisi Shell Preheating: Flow area, as =
ID. C' . B 144 . PT
keterangan : as = luas untuk aliran fluida, ft² ID = diameter dalam shell, in B = jarak baffle, in PT = pitch, in
7
C' = clearence = PT - D0 Flow area, as =
(39/12)(0.19)(6) 144 . (0,94)
= 0,328 ft² Diameter ekuivalen, De = 0.95 in = 0.0792 ft ( fig.28 Kern ) Kecepatan massa, GS = W/as Gs = 54980,1/ 0,328 = 167388,806 lb/j.ft² Ta = (T1 + T2)/2 = (99,256 + 101,212)/2 = 100,234°C = 212.421ºF Sifat - sifat fisis pada suhu 100,234°C : = 0,09 Btu/lb.°F µ = 0.07 lb/j.ft k = 0,0135 Btu/j.ft.°F Bilangan Prant'l, Pr = c .µ /k =
0.09 x 0,07 = 4,67E-01 0.0135
Bilangan Reynold, Res = Gs.De/µ =
167388,806 x 0.0792 = 189388,478 0.07
Dari figur 28 Kern, 1965 didapat : faktor perpindahan panas, jH = 290 ho
De
jH = x k ho
ho
x (Prs)-1/3
= jH x
k x (Prs)1/3 De
= 290x
0.0135 x (4,67E-01)1/3 0.0792
φ≈1 ho = shell out heat transfer coefficient, Btu/j.ft2.oF = 38,342 Btu/j.ft².°F Clean overall coefficient for preheating, Up: Up
=
1500 x 38,342 hio . ho = 1500 38,342 hio ho
= 37,386 Btu/j.ft².°F Clean surface required for preheating, Ap:
8
7642430 Btu / j 0 F
qp
Ap = Up . tp = = 204417,284 ft² 37,386 Btu/j.ft 2 . 0 F Vaporization : Sifat - sifat fisis pada suhu 109,7°C : c = 0,45 Btu/lb.°F µ = 0,014 = 0,0315 lb/j.ft k = 0,0142 Btu/j.ft.°F Bilangan Prant'l, Pr = c .µ /k =
0.45x 0.0315 = 0,998 0.0142
Bilangan Reynold, Res = Gs.De/µ =
167388,806 x 0.0792 = 420863,285 0.0315
Dari figur 28 Kern, 1965 didapat : faktor perpindahan panas, jH = 480 ho
De
jH = x k ho
ho
= jH x = 480 x
x (Prs)-1/3
k x (Prs)1/3 De 0.0142 x (0,998)1/3 0.0792
φ≈1 ho = 86,010 Btu/j.ft².°F Clean overall coefficient for vaporization, Uv: Uv
=
1500 x 86,010 hio . ho = 1500 86,010 hio ho
= 81,346 Btu/j.ft².°F Clean surface required for vaporization, Av: qv
26414600 Btu / j 0 F
Av = Up . tv = = 324720,280 ft² 81,346 Btu/j.ft 2 . 0 F Total clean surface, Ac: Ac = Ap + Av = 204417,284 + 324720,280 = 529137,564 ft² Weighted clean overall coefficient
9
Uc
U.A
=
Ac
=
(37,386 x 204417,284 (81,346 x 324720,280) 529137,564
= 78,363 Btu/j.ft².°F Dirt factor : Rd
78,363 - 63 Uc - UD = 78,363 x 63 Uc . UD
=
= 0,00311 /(Btu/j.ft².°F) Rd minimum = 0.003 Cek flux maksimum : Luas transfer panas yang digunakan untuk penguapan: 324720,280 Av xA x 8647,560 = 5306,821 ft² 529137,564 Ac 7642430 qv = = 8647,560 = 883,767 Btu/j.ft² A
= Flux
Flux maksimum = 20000 Btu/j.ft² ( Kern,1965) PENURUNAN TEKANAN Sisi Tube Pt
f.Gt².L.n
= 0.5 5,22.1010.D.S.
Dimana: f = friction factor Gt = kecepatan aliran massa dalam tube, lb/j L = panjang pipa. ft D = diameter tube, ft S = specific gravity
Ret =
7064,217
10
Dari fig.26 Kern 1965, f = 0.00027 D Gt
= 1,4 in = 0,1167 ft = 2446,238 lb/j.ft² ρ = 17.4444 lb/ft3
Sp.gravity, S = ρ/62.5 = 0.279 Pt
= 0.5
(0.00027).(2446,238)².(16).(1) (5.22 x 1010 ).(0.1167) .(0.279).(1)
= 0,0000076 Psi dP allowble (gas ) = max 10 psi Sisi Shell Preheating : Ps =
f.Gs².Ds.(N 1) 5,22.1010.D.S.
Bilangan Reynold, Res = Gs.De/µ = 189388,478 Untuk Res = 189388,478 dari fig.29 Kern, didapat f = 0.00013 Panjang zone preheating, Lp = L.Ap/Ac = 6,181 ft Jumlah cross, N+1 = 12.Lp/B N + 1 = 12 x 6,181/ 7 = 12,362 Pada ta = 99,220°C ρ
= 17,6316 lb/ft3
Sp.gravity, S = ρ/62.5 = 0.282 ID shell = 39 in = 3,25 ft Gs
= 167388,806 lb/j.ft²
Ps
=
(0.00013).(167388,806 ) 2 .(3,25).(12,326) (5.22 x 1010 ).(0.0792).(0.282).(1)
= 0,126 Psi Vaporization : Bilangan Reynold, Res = Gs.De/µ Re = 36841,702 Untuk Res = 45705 dari fig.29 Kern, didapat f = 0,00011 Panjang zone vaporization, Lv = L-Lp = 16 – 13,926 = 2,074 ft Jumlah cross, N+1 = 12.Lp/B
11
N + 1 = 12 x 2,074 / 7 = 3,556 Pada ta = 109,7 °C ρ uap = 17.4444 lb/ft3 sp gas = 0.279 S rata-rata = (0.282 + 0.279)/2 = 0,281 Ps
=
(0.00011). (167388,806) 2 .(3,25).(19,638) (5.22 x 1010 ).(0.0792).(0.281).(1)
= 0,17 Psi Pressure Drop di Shell = 0,126 + 0,17 = 0,295 Psi Summary Tube 1500
Shell h outside
38,342
86,010 Uc 78,363 UD 62,841 Rd hitung 0,00311 Rd minimum 0.003 0,0000076 P hitung 0,295 2
P maksimum
10
Spesifikasi alat vaporizer Fungsi
: Menguapkan air dan sedikit aseton sebanyak 19950,843 kg/j dari hasil recycle menara distilasi (MD-01) yang selanjutnya dipisahkan antara uap dan cairan dalam separator untuk diumpankan kembali dalam reaktor.
Tube
: OD = 0,75 in ; 16 BWG ; 0,94 in triangular pitch ; Nt = 1377 tube ; 1 es
Luas Transfer Panas (A) Shell
: 8647,560 ft² : ID =39 in ; 1 es
12
Jenis
:HE Shell and Tube
Beban Panas Jumlah
: 8582224,969 kkal/j : 1 buah
13
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