Page 248 - Chemical engineering design

224
CHEMICAL ENGINEERING
Solution
3
Ž
ODCB density at 20 C D 1306 kg/m .
2
Viscosity: 0.9 mNs/m (0.9 cp).
Estimation of pipe diameter required
typical velocity for liquid 2 m/s
10,000
mass flow D D 2.78 kg/s
3600
2.78
3
volumetric flow D D 2.13 ð 10 3 m /s
1306
volumetric flow 2.13 ð 10 3
area of pipe D D D 1.06 ð 10 3 m 2
velocity 2

4

diameter of pipe D 1.06 ð 10 3 ð D 0.037 m

D 37 mm
Or, use economic pipe diameter formula:

d, optimum D 293 ð 2.78 0.53 ð 1306 0.37 5.14
D 35.4mm
Take diameter as 40 mm
3 3 2
cross-sectional area D 40 ð 10 D 1.26 ð 10 m
4

Pressure drop calculation

2.13 ð 10 3
fluid velocity D D 1.70 m/s
1.26 ð 10 3
Friction loss per unit length, f 1 :

1306 ð 1.70 ð 40 ð 10 3 4
Re D D 9.9 ð 10 5.5
0.9 ð 10 3
Absolute roughness commercial steel pipe, table 5.2 D 0.46 mm
Relative roughness, e/d D 0.046/40 D 0.001
Friction factor from Figure 5.7, f D 0.0027

1 1.7 2 2
f 1 D 8 ð 0.0027 ð ð 1306 ð D 1019 N/m 5.3
3
40 ð 10 2
D 1.02 kPa