Upload
david-lambert
View
499
Download
17
Embed Size (px)
Citation preview
8/13/2019 Design and Calculation Dryer
1/38
Bahan yang dikeringkan Sorghum
Type Rectangular bin batch dryer
Capacity 2.5 Ton
with moisture content 10% w.b
Direncanakan :
Suhu Udara Ambient 30oC
Relative Humidity Udara Ambient 70%
Moisture content awal 15% w.b
Moisture content akhir 10% w.b
Grain inlet temperature 30 tG1
Grain outlet temperature 70 tG2
Heated Air Temperature 85 t2
Exhaust Air Temperatur 40 t1
Panas Laten uap air 600 Kcal/Kg
(from grain parameter tables 6.3)
Thickness of grain to be dried 45 cm
Buck Density of Sorghum grain
at 10% moistureadalah 752.9 kg/m
3
(from grain parameter tables 6.2)
Dimension of plenum 8 x 7
56 ft2
Drying time 1 jam
Asumsi :
Spesific heat of grain 0.3934 Kcal/Kg.oC
Tinggi dari dryer, H
H= Tinggi dari bin dan tinggi dari plenum chamber
H= 1.5 + 0.75 + 3
H= 5.25 ftVolume dari Plenum Chamber 8 x 7 x 0.75
42 ft3
Volume dari drying chamber 3.32049409 m3
3,320,494 cm3
3.32E+09 mm3
Kebutuhan udara
Bone dry Sorghum 2,250 Kg
Moisture content awal 15% w.b
17.65 d.b
Moisture content akhir 10% w.b11.11 d.b
Berat kandungan air yg diuapkan 147.06 Kg
Dari Psychrometric Chart , diperoleh
Absolute humidity dari udara ambient 0.019 Kg/Kg
Humid Heat dari udara ambient
S = 0.24 + 0.45 H 0.24855 Kcal/Kg.oC
apabila G adalah
Rate dari udara yg disupply dalam Kg/min
8/13/2019 Design and Calculation Dryer
2/38
maka = G.S.(t1- t2).Co 671.09 G
i) Panas sensible dari grain 35,406 Kkal
ii) Panas sensible dari air
total berat dari air 397 Kg
spesific heat dari air 1.00 Kcal/Kg.oC
Panas sensible dari air 15,882.35 Kkal
iii) Panas laten dari uap air 88,235.29 Kkal
Total Heat Utilized 139,524 Kkal
Asumsi
Jika Heat Loss 10%
maka
Net Panas dibutuhkan 155,026 Kkal
Jika Heat Loss 20%
maka
Net Panas dibutuhkan 174,405 Kkal
maka nilai G adalah sebesar 231 Kg/menit
Dari Psychrometric Chart,
Humid volume dari udara ambient 0.884 m3/Kg
Maka diperlukan udara sebanyak 205.00 m3/menit
7,244.70 CFM
Surface Area dari Plenum Chamber 56 ft2
since maximum 50% area is perforated
area through which air passes 28 ft2
Udara yang diperlukan per ft2 = 258.74 cfm/ft2
Dari kurva shedd's, diperoleh Static Pressure drop
Utk 260 cfm/ft2
3 inch of water per 1 ft grain depth
Depth of grain 1.5 ft
maka pressure dropnya 4.5 inch of water
Packing of the grain in bin may cause 50% higher resistance to airflow than the values shown
Total Pressure drop 6.75 inch of water
Add the static pressure drop from the duct and floor, usually about 1/4 in water if the air velocity is kept at 1,0
7 inch of water
17.78 cm of water
Density dari udara 1.13 Kg/m3
Pressure drop in terms of air column 157.35 m
HP requiredHeight of air column 157.35 m
8.08
dibulatkan 10 HP
Heating System:
q'a Total heat required to heat the drying air 155,026 kkal/jam
Cn Calorific value of fuel, 41,263 kkal/kg dari bahan bakar
8/13/2019 Design and Calculation Dryer
3/38
efficiency of the heating system 1
b efficiency of the boiler 1
ex efficiency of the heating exchanger
Bahan bakar yg dikonsumsi sebanyak 15.73 Kg/jam
Petrol 15
Kerosene 15
LPG 14
Wood 32
Bagass (dry) 35
Cotton batting 40
Wheat 38
Pemilihan Blower Sentrifugal
1) Spesific Speed (Ns)
N Speed of motor 1440 RPM
Q Laju Alir Udara 7,244.70
Ps Static pressure, m wake gauge or inch 7
Spesific Speed (Ns) 28,481
2) Dari fig. 6.1, dimana ada 2 unit yg cukup efisien pada nilai Ns =
28,481
3) Dari tabel 6.1, diperoleh
= 1.5
4) karena = 2.35x10^8xPs/(N^2.d^2)
d2= 528.87
d = 23.00 inch
584.13 mm
5) dari Tabel 6.5
diperoleh = 0.62W=175*Q/(.N.d^2) 2.685 inch
68.20 mm
dipilih 67 mm
Blower Housing
Width of housing, M
M = 1.25 W + 0.1 d 142.16 mm
Diffuser Angle
w = -9.079488754
10o
8/13/2019 Design and Calculation Dryer
4/38
8/13/2019 Design and Calculation Dryer
5/38
8/13/2019 Design and Calculation Dryer
6/38
8/13/2019 Design and Calculation Dryer
7/38
00 fpm or less
8/13/2019 Design and Calculation Dryer
8/38
8/13/2019 Design and Calculation Dryer
9/38
8/13/2019 Design and Calculation Dryer
10/38
8/13/2019 Design and Calculation Dryer
11/38
8/13/2019 Design and Calculation Dryer
12/38
8/13/2019 Design and Calculation Dryer
13/38
8/13/2019 Design and Calculation Dryer
14/38
8/13/2019 Design and Calculation Dryer
15/38
8/13/2019 Design and Calculation Dryer
16/38
8/13/2019 Design and Calculation Dryer
17/38
8/13/2019 Design and Calculation Dryer
18/38
8/13/2019 Design and Calculation Dryer
19/38
8/13/2019 Design and Calculation Dryer
20/38
8/13/2019 Design and Calculation Dryer
21/38
8/13/2019 Design and Calculation Dryer
22/38
8/13/2019 Design and Calculation Dryer
23/38
8/13/2019 Design and Calculation Dryer
24/38
8/13/2019 Design and Calculation Dryer
25/38
8/13/2019 Design and Calculation Dryer
26/38
8/13/2019 Design and Calculation Dryer
27/38
8/13/2019 Design and Calculation Dryer
28/38
8/13/2019 Design and Calculation Dryer
29/38
8/13/2019 Design and Calculation Dryer
30/38
8/13/2019 Design and Calculation Dryer
31/38
8/13/2019 Design and Calculation Dryer
32/38
8/13/2019 Design and Calculation Dryer
33/38
8/13/2019 Design and Calculation Dryer
34/38
8/13/2019 Design and Calculation Dryer
35/38
8/13/2019 Design and Calculation Dryer
36/38
8/13/2019 Design and Calculation Dryer
37/38
8/13/2019 Design and Calculation Dryer
38/38