Particulate Emission Control - Mathematics and Statistics for the Environment - page 501

TABLE 17.1
Particle Size Distribution Data

Inlet

Average Particle
Diameter (µm) Particle Size Range ( µm) Grains/scf wt%

0-20 10 0.0062 2.7

20-30 25 0.0159 6.9

30-40 35 0.0216 9.4

40-50 45 0.0242 10.5

50-60 55 0.0242 10.5

60-70 65 0.0218 9.5

70-80 75 0.0161 7.0

80-94 85 0.0218 9.5

94 94 0.0782 34.0

Total — 0.2300 100.0

efficiency for a settling chamber can be expressed in terms of the terminal settling velocity, volu-
metric flow rate of contaminated stream, and chamber dimensions:

()

2

gp d

BL
Q =

BL
Q

pp

η = v

18 µ

where
η = Fractional collection efficiency.
v = Terminal settling velocity.
B = Chamber width.
L = Chamber length.
Q = Volumetric flow rate of the stream.

Express the collection efficiency in terms of particle diameter d p . Replace the terminal settling
velocity in the above equation with Stokes' law. Because the actual terminal settling velocity is
assumed to be one-half of the Stokes' law velocity (according to the given problem statement), the
velocity equation becomes

= ()

2

gp d

pp

v

36 µ

()

2

gp d

BL
Q

pp

η =

36 µ

Determine the viscosity of the air in lb/ft-s:

Viscosity of air at 446°F = 1.75 × 10 -5 lb/ft-s

Determine the particle density in lb/ft 3 :

p p = 2.65(62.4) = 165.4 lb/ft 3