Page 332 - APPLIED PROCESS DESIGN FOR CHEMICAL AND PETROCHEMICAL PLANTS, Volume 1, 3rd Edition

300 Applied Process Design for Chemical and Petrochemical Plants

Figure 5-11. Pumping number is the basis for design procedures involving blending and motion. By pennission, Hicks, R. W., et. al., Chem.
Eng., Apr. 26, 1976, p. 104 [28).

D; = impeller diameter, in. Representative Cr values from [28) are:
µ' = fluid viscosity, centipoise
µ=fluid viscosity, lb/sec ft
p = fluid density, lb/cu ft NRe c, in.
Sg = fluid specific gravity, (not density) 700 1.0
NP = power no. 400 0.98
200 0.95
The Froude number is [33): 100 0.91
70 0.89
60 0.88
DN 2 (5- 9) 50 0.87
g

g = gravitational constant, 32-ft/sec-sec In general, below a Reynolds number of 50, all
impellers give viscous flow mixing; between 50 and 1,000
the pattern is in the transition range; and from NRe above
Estimated turbine impeller diameter [28): 1000 the action is turbulent.

(5-10) For NRc � 10, the liquid motion moves with the
impeller, and off from the impeller, the fluid is stagnant
[34). The Froude number accounts for the force of gravi-
Calculate Reynolds number, NRc, from Equation 5-8,
then correct for viscosity effects. ty when it has a part in determining the motion of the
fluid. The Froude numbers must be equal in scale-up sit-
uations for the new design to have similar flow when grav-
(5-11) ity controls the motion [16).