VIII - 30
Pra Rencana Pabrik Urea Formaldehyde Concentrate
Tipe : Centrifugal pump
Bahan : Commercial steel
Rate volumetrik : 122,4251 gpm
Total Dynamic Head : 27,15 ft lbflbm Effisensi motor
: 82 Power
: 3 hp Jumlah
: 1 buah
2. Pompa Bak Koagulasi – Flokulasi
L - 221
Fungsi = Untuk mengalirkan air dari A – 210 ke A – 220.
Tipe = Centrifugal pump
ρ air = 62,43 lb cuft
Rate bahan = 28,8002 m
3
jam = 122,4251 gpm = 0,2825 cuft dt
Asumsi aliran turbulen :
Diameter Optimum = 3.9 x qf
0,45
x ρ
0,13
Peter Timmerhaus 4ed, pers. 15 Diameter pipa optimum = 3,7995 in
Dipilih pipa 4 in, sch 40 Foust, App. C6a
A - 210 L - 221
P
1
V
1
A B
P
2
V
2
∆ Z
A - 220
reference plane
18 ft 10 ft
5 ft 7 ft
VIII - 31
Pra Rencana Pabrik Urea Formaldehyde Concentrate
OD = 4,5 in ID = 4,026 in = 0,3355 ft
A = 0,0884 ft
2
Kecepatan aliran, V =
pipa k
volumetri rate
area
2
cuftmnt ft
x
dtmnt 60
1
=
0884 ,
16,9512
X
60 1
=
3,1959 ftdt = 0,00054 lbft dt berdasarkan sg bahan
N
Re
= µ
ρ v
D = 124520,107 2100
asumsi turbulen benar Dipilih pipa commercial steel
= 0,00045 f = 0,048
Diguakan persamaan Bernoulli : F
x gc
x 2
v gc
g Z
P
2
∑ +
∆ +
∆ +
∆ =
− α
ρ Wf
Perhitungan Friksi berdasarkan Peters Timmerhaus 4
ed
, tabel 1, hal. 484.
Taksiran panjang pipa lurus = 40 ft
Panjang ekuivalen, Le
-
4 elbow 90 ˚
= 4 x 32 x 0,3355 = 32,2080 ft
-
1 globe valve = 1 x 300 x 0,3355
= 100,6500 ft
-
1 gate valve = 1 x 7 x 0,3355
= 2,3485 ft Panjang total pipa
= 175,2065 ft
Friksi yang terjadi :
VIII - 32
Pra Rencana Pabrik Urea Formaldehyde Concentrate
1. Friksi karena gesekan bahan dalam pipa.
D Le
v f
2
2 1
× ×
× =
gc F
=
m f
2
lb lb
ft 1,5902
0,3355 2,2
3 175,2065
3,1959 0,0048
2 =
× ×
× ×
2. Friksi karena kontraksi dari tangki ke pipa [Peters Timmerhaus 4
ed
, hal 484]
2 v
2 2
2
gc K
F ×
× ×
= α
K = 0,4, A tangki A pipa.
m f
2
lb lb
ft 0,0634
2,2 3
1 2
3,1959 ,4
= ×
× ×
=
3. Friksi karena enlargement ekspansi dari pipa ke tangki. 0,1586
32,2 1
2 3,1959
2 v
2 2
2 3
= ×
× −
= ×
× ∆
= gc
F α
m f
lb lb
ft
1,8123 0,1586
0,0634 1,5902
F F
3 2
1
= +
+ =
+ +
=
∑
F F
m f
lb lb
ft
P
1
= P
hidrostatik
= ρ
g h = 62,43 x 1 x 4,1798 = 260,9435 lb
f
ft
2
P
2
= 1 atm = 2116,8 lb
f
ft
2
1 atm = 14,7 x 144 lb
f
ft
2
P = P
2
– P
1
= 1855,8565 lb
f
ft
2
; ∆P
ρ = 29,7270 ft lb
f
lb
m
0,1586 32,2
1 2
3,1959 2
v
2 2
2
= ×
× −
= ×
× ∆
gc α
ft lb
f
lb
m
Z
1
= 4,1798 ft Z
2
= 18 ft ∆Z = Z
2
+ Z
1 =
18 -4,1798 = 13,8202 ft ; ∆Z ggc = 14
m f
lb lb
ft
Persamaan Bernoulli : F
x gc
x 2
v gc
g Z
P
2
∑ +
∆ +
∆ +
∆ =
− α
ρ Wf
VIII - 33
Pra Rencana Pabrik Urea Formaldehyde Concentrate
-Wf = 29,7270 + 14 + 0,1586 + 1,8123 = 45,5181
m f
lb lb
ft
Sg campuran Himmelblau : berdasarkan sg bahan = 1
960 3
sg gpm
flowrate p
× ×
− =
Wf h
Perry 6ed ; pers 6-11 ; hal. 6-5.
hp 1,4072
3960 1
122,4251 45,5181
= ×
× =
Effisiensi pompa = 45
Peters Timmerhaus 4ed ; fig. 14-37 Bhp
=
hp 3,1271
45 1,4072
pompa =
=
η
hp
Effisiensi motor = 80
Peters Timmerhaus 4ed ; fig. 14-38 Power pompa
=
hp 4
3,9089 80
3,1271 pompa
≈ =
=
η
hp
Spesifikasi : Fungsi
: Untuk mengalirkan air dari A – 210 ke A – 220.
Tipe : Centrifugal pump
Bahan : Commercial steel
Rate volumetrik : 122,4251 gpm
Total Dynamic Head : 45,5181 ft lbflbm Effisensi motor
: 80 Power
: 4 hp Jumlah
: 1 buah
3. Pompa Bak Pengendap L - 231
