Page 254 - Water and wastewater engineering
P. 254
COAGULATION AND FLOCCULATION 6-31
1000
300 mm
250 mm
350 mm 600 mm
100 200 mm 400 mm
150 mm
Pressure drop per element, kPa 10 1 700 mm
0.1
0.01
1 10 100 1000 10000
3
Flow rate, m /h
FIGURE 6-16
Typical static mixer pressure drop selection graph for pipe diameters from 150 mm to
700 mm.
• Using either an equation or a graph, such as that shown in Figure 6-16 provided by the
manufacturer, determine the pressure drop per element.
• With the pressure drop per element and the number of elements, estimate the detention
time, water power, and velocity gradient, and check these against the design criteria.
The detention time is calculated with Equation 6-13 . The power imparted by static mixing devices
may be computed using Equation 6-16 . The velocity gradient is calculated with Equation 6-12 .
QH
P (6-16)
where P water power, kW
3
specific weight of fluid, kN/m
3
9.807 kN/m for water at 5 C
3
Q flow rate, m /s
H total dynamic head, m
efficiency
