Page 249 - Chemical engineering design

PIPING AND INSTRUMENTATION
Design for a maximum flow-rate of 20 per cent above the average flow.
2
Friction loss D 1.02 ð 1.2 D 1.5kPa/m 225
Miscellaneous losses
Ž
Take as equivalent pipe diameters. All bends will be taken as 90 standard radius elbow.
Line to pump suction:

length D 1.5 m
bend, 1 ð 30 ð 40 ð 10 3 D 1.2 m
valve, 1 ð 18 ð 40 ð 10 3 D 0.7 m
3.4 m
u 2
entry loss D see Section 5.4.2
2
1306 1.7 ð 1.2 2
at maximum design velocity D D 2.7kPa
2 ð 10 3

Control valve pressure drop, allow normal 140 kPa
2
ð1.2 maximum 200 kPa
Heat exchanger, allow normal 70 kPa
2
ð1.2 maximum 100 kPa
Orifice, allow normal 15 kPa
2
ð1.2 maximum 22 kPa
Line from pump discharge:
length D 4 C 5.5 C 20 C 5 C 0.5 C 1 C 6.5 C 2 D 44.5 m
bends, 6 ð 30 ð 40 ð 10 3 D 7.2m D 7.2 m
valves, 3 ð 18 ð 40 ð 10 3 D 2.2m D 2.2 m
54.0 m

The line pressure-drop calculation is set out on the calculation sheet shown in Table 5.4.
Pump selection:
3
flow-rate D 2.13 ð 10 3 ð 3600 D 7.7m /h
differential head, maximum, 44 m
select single-stage centrifugal (Figure 5.6)